BIOMASS ASH-BASED HETEROGENEOUS CATALYSTS TO PRODUCE FATTY ACID METHYL ESTERS FROM WASTE COOKING OIL by Harpuneet Singh Ghuman BEng., Panjab University, 2010 THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTERS OF SCIENCE IN NATURAL RESOURCES AND ENVIRONMENTAL STUDIES UNIVERSITY OF NORTHERN BRITISH COLUMBIA September 2013 © Harpuneet Singh Ghuman, 2013 UMI Number: 1525713 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. Di!ss0?t&iori Publishing UMI 1525713 Published by ProQuest LLC 2014. Copyright in the Dissertation held by the Author. Microform Edition © ProQuest LLC. All rights reserved. This work is protected against unauthorized copying under Title 17, United States Code. ProQuest LLC 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 48106-1346 ABSTRACT Biodiesel is widely accepted for blending with conventional fuels such as diesel and gasoline. The development o f cheap, durable heterogeneous catalysts for its production is a rapidly growing field o f scientific investigation. Two heterogeneous catalysts were prepared from ashes o f wood gasification (GA) and wood pellet combustion (PBA). They were characterized and subsequently used in the transesterification of waste cooking oil (>1% FFA) to produce biodiesel. The methanol to oil ratio was 12:1 and 5 wt% catalyst was used over temperatures of 65 °C, 80 °C, 120 °C and 160 °C. 'H-NMR was used to establish yield o f the trans-esterification reaction. The maximum yield using PBA catalyst was 95% at 120 °C and 155 minutes, for GA catalyst, it was 95% yield at 120 °C and 160 minutes. The re-use of both catalysts was also investigated at 120 °C, 12:1 methanol to oil ratio and 5 wt% catalyst. The PBA catalyst upon reuse at 120 °C gave a yield of 75% at 160 minutes and fared better than the GA catalyst, which gave 60% yield after 300 minutes at 120 °C. TABLE OF CONTENTS Abstract ..................................................................................................... ii Table o f Contents ..................................................................................................... iii List of Tables ..................................................................................................... v List o f Figures ..................................................................................................... vi Glossary Acknowledgement ix ..................................................................................................... Co- authorship statement Chapter 1 Chapter 2 x xi Introduction............................................................................... 1 1.1 Overview o f biodiesel production processes...................... 1.1.1. Waste feedstock for biodiesel production 1.1.2. Catalysts for biodiesel production from waste feedstock............................................................ 1.1.3. Environmental and Economic benefits o f using waste feedstock....................................... 1.1.4. Conclusions....................................................... 1.2 Biomass to energy............................................................... 1.2.1 Introduction....................................................... 1.2.2 Ash production and utilization......................... 1 5 9 14 15 18 18 21 Pellet burner bottom ash as a heterogeneous catalyst for fatty acid methyl ester production......................................... 26 2.1 Introduction.......................................................................... 2.2 Experimental........................................................................ 2.2.1 Materials and methods...................................... 2.2.2 'H-NMR method.............................................. 2.2.3 Catalyst preparation.......................................... 2.2.4 Experimental procedure.................................... 2.3 Results and discussion........................................................ 2.3.1 Catalyst characterization................................... 2.3.2 Reaction yield and catalyst performance 2.3.3 Catalyst re-use................................................... 2.4 Conclusions......................................................................... 26 31 31 32 32 33 34 34 46 53 55 iii Biomass gasification residue as a heterogeneous catalyst for biodiesel production.......................................................... 58 3.1 Introduction......................................................................... 3.2 Experimental...................................................................... 3.2.1 Materials and methods...................................... 3.2.2 'H-NMR method............................................... 3.2.3 Catalyst preparation.......................................... 3.2.4 Experimental procedure.................................... 3.3 Results and discussion....................................................... 3.3.1 Catalyst characterization.................................. 3.3.2 Reaction yield and catalyst performance........ 3.3.3 Catalyst re-use................................................... 3.4 Conclusions......................................................................... 58 63 63 64 65 65 66 66 84 85 87 Comparative analysis of two heterogeneous catalysts....... 88 4.1 Introduction......................................................................... 4.2 Inorganic content................................................................ 4.3 Catalyst performance.......................................................... Conclusions and Recommendations for future work.......... 88 88 91 97 99 112 113 iv List of Tables Table 1.1 Table showing vegetable oil consumption (for food purposes) in top 5 regions of the world averaged from 2010/11-2011/12........................ 8 Table 1.2 Summary of recent research on using waste feedstock to produce biodiesel. The table depicts the type o f feedstock and catalyst, along with best yields and corresponding reaction conditions........................ 13 Table 1.3 Estimate o f potential ranges o f net ash production based on complete wood residue, wood fuel utilization in top five countries in the world.. 23 Table 2.1 Elemental concentrations in pellet burner ash, sieved ash (<150pm) and PBA catalyst as found by ICP-MS.................................................... Table 2.2 Composition o f PBA and PBA catalyst as determined by XRD Table 3.1 Table 3.2 35 44 Elemental concentrations in gasifier ash, sieved ash (<150pm) and GA catalyst as found by ICP-MS............................................................ 66 Composition of GA and GA catalyst as determined by XRD............... 74 v List of Figures Figure 1.1 World Vegetable oil production, 2002-2012.................................... 4 Figure 2.1 Scanning electron microscopy at 2500x magnification for Pellet burner ash after sieving through <150 pm ...................................... 36 Scanning electron microscopy at 2500x magnification for PBA catalyst................................................................................................ 37 XRD o f PBA (<150 pm) before calcination for 2 0 0° to 70°. The peak markers show the relation between experimental data and best fit patterns for the identified materials..................................... 38 XRD o f PBA catalyst for 2 0 from 0° to 80°. The peak markers show the relation between experimental data and best fit patterns for the identified materials............................................................... 39 Figure 2.5 FT-IR spectroscopy o f pellet burner ash (<150 pm )........................ 40 Figure 2.6 FT-IR of catalyst prepared from pellet burner ash........................... 41 Figure 2.7 TGA curves o f catalyst and ash at heating rate of 10°C/ min 42 Figure 2.8 Time based overlap 'H-NMR o f samples for the reaction at 120°C, 12:1 Methanol to oil molar ratio and 5 wt% catalyst 47 Figure 2.2 Figure 2.3 Figure 2.4 Figure 2.9 Figure 2.10 'H-NMR region showing Triacylglycerol (TAG) as a doublet o f doublets with no overlap or interference by reaction intermediates for 120° C at............................................................... (a) 35 minutes (b) 60 minutes of reaction 48 Conversion of oil to methyl ester using calcined ash as catalyst. The reaction conditions were 5 (wt %) catalyst, 80° C and a 12:1 molar ratio o f methanol to oil........................................................... 50 Figure 2.11 Conversion o f oil to methyl ester using PBA catalyst. The reaction conditions were 5 (wt%) catalyst, 120° C and a 12:1 molar ratio o f methanol to oil........................................................... 51 Figure 2.12 Conversion o f oil to methyl ester using PBA catalyst. The reaction conditions were 5 (wt%) catalyst, 160° C and a 12:1 molar ratio of methanol to oil........................................................... 52 vi Figure 2.13 Conversion o f oil to methyl ester using recycled PBA catalyst. The reaction conditions were 5 (wt%) recycled catalyst, 120° C and a 12:1 molar ratio o f methanol to oil....................................... 54 Figure 3.1. TGA curves o f catalyst and ash at heating rate o f 10°C/ m in 68 Figure 3.2 SEM image at 2500x magnification of gasifier ash as received after sieving to particle size < 150pm............................................... 69 Figure 3.3 SEM image at 2500x magnification o f PBA catalyst..................... 70 Figure 3.4 XRD o f GA (<150 pm) for 2 0 0° to 80°. The peak patterns marked over the experimental pattern show the relation between experimental data and best fit patterns for the identified materials............................................................................................ 71 XRD of GA catalyst prepared after calcination, for 2 0 0° to 85°. The different peak patterns marked over the experimental pattern show the relation between experimental data and best fit patterns for the identified materials............................................................... 72 Figure 3.6 FT-IR spectrum o f gasifier ash <150 pm .......................................... 76 Figure 3.7 FT-IR spectrum o f catalyst prepared upon calcination o f the ash.. 77 Figure 3.8 1H-NMR spectra overlap o f samples at different times, for the reaction at 120°C, 12:1 Methanol to oil molar ratio and 5 wt% catalyst................................................................................................ 78 'H-NMR region from 4 - 4 . 5 ppm chemical shift showing Triacylglycerol (TAG) as a doublet o f doublets with no overlap or interference by reaction intermediates for.................................. 79 Figure 3.5 Figure 3.9 (a) 90 minutes at 65° C (b) 20 minutes at 120 °C. The figure shows the conversion of oil to methyl ester using GA catalyst and the control reaction using untreated ash. The reaction conditions were 5 (wt %) catalyst, 65° C and a 12:1 molar ratio o f methanol to oil........................................................... 80 Figure 3.11 The figure shows the conversion of oil to methyl ester using GA catalyst. The reaction conditions were 5 (wt %) catalyst, 80° C and a 12:1 molar ratio o f methanol to oil....................................... 81 Figure 3.10 vii Figure 3.12 Figure 3.13 Figure 4.1 Figure 4.2 Figure 4.3 Conversion of oil to methyl ester using GA catalyst and control reaction using untreated ash. The reaction conditions were 5 (wt %) catalyst, 120° C and a 12:1 molar ratio of methanol to oil 82 Conversion of oil to methyl ester using recycled gasifier ash as catalyst. The reaction conditions were 5 (wt %) recycled catalyst, 120° C and a 12:1 molar ratio o f methanol to oil 86 Conversion of oil to methyl ester using PBA and GA catalysts. The reaction conditions for both reactions were 5 (wt %) catalyst, 120° C and a 12:1 molar ratio o f methanol to o il 95 Conversion of oil to methyl ester using PBA and GA catalysts. The reaction conditions for both reactions were 5 (wt %) catalyst, 80° C and a 12:1 molar ratio o f methanol to oil............... 96 Conversion o f oil to methyl ester using recycled PBA and GA catalysts. The reaction conditions for both reactions were 5 (wt %) recycled catalyst, 120° C and a 12:1 molar ratio o f methanol to oil.................................................................................................... 97 viii Glossary BET Brunauer Emmet Teller theory for determining surface area o f solid 1,2-DAG 1,2 - diacylglycerol FAEE Fatty acid alkyl ester FAME Fatty acid methyl ester FAO Food and Agriculture Organization FFA Free fatty acid FT-IR Fourier transform infrared spectroscopy GA Gasifier ash GHG Green house gas ICDD International Centre for Diffraction Data ICP-MS Inductively coupled plasma with mass spectrometer 1-MAG 1 - monoacylglycerol 'H-NM R Nuclear magnetic resonance ('H) PBA Pellet burner ash TAG Triacylglycerol TGA Thermo gravimetric analysis TMS Tetramethylsilane USDA United States Department of Agriculture W CO Waste cooking oil XRD X-ray diffraction ix Acknowledgement I would like to express immense gratitude to my supervisor Dr. Ronald W. Thring for providing me with an excellent research opportunity. He cultivated my ideas, nourished rational thought and guided me through the course of this research project. His motivation and support in every form has proved crucial for my development as a researcher. I also thank Dr. Joselito Arocena for being immensely helpful with access to equipment and training. Dr. Arocena accommodated my numerous questions and doubts about various aspects o f the materials analysis. I must also thank Dr. Jianbing Li and Dr. Saif Zahir for being on my committee and providing encouragement and invaluable feedback from time to time. Dr. Balbinder Deo has provided me with motivation and laughs that I am highly grateful for. I must thank my two partners in crime, Adrian James and Gurkaran Sarohia. They have been vital to the success o f the project. They have contributed generously, lending a hand in lab procedures and giving motivational speeches when a graduate student most needs them. My friend Nathan Park has been instrumental in my acclimatization to a new country and culture. He provided me with routine advice about lab procedures and introduced me to an unwavering work ethic. My friends Bobby Chavarie, Mateusz Partyka, Amy Thommassen, Jordan Keim, Guneet Sidhu and Vishavpreet Brar have all been the source o f immense support and inspiration. I must thank every single one o f you for giving me a home away from home. Special thanks and love to all my friends from India, especially Jasmine Brar, Nikhil Jain, Avijeet Singh and Anoop Arora. You have provided amazing long distance support, for which I’m highly grateful. Lastly, I must thank my father and mother Dr. B.S. Ghuman and Dr. Dhian Kaur. They have encouraged me to pursue academics, consistently pushed me to achieve the best, stimulated my rational thought and given me an excellent set o f values and ideals to strive for. My brother, Parveer Ghuman who has actively engaged in challenging everything I do with a firm resolve to make me a better person. Other members o f my family, Dr. Sikander S. Gill, Dr. Raj want Gill, Divkaran Gill and Lishkaran Gill have encouraged me, and provided much needed advice and support. x Co-authorship statement I conducted all experimental work, data analysis and prepared all the drafts of manuscripts in this thesis. The manuscripts appear as separate chapters based on the research and its results. All drafts o f the manuscripts and publications have been reviewed and strengthened through input given by my supervisor Dr. Ronald Thring. Other persons who have been instrumental in the successful completion and editing of the individual studies are: Gurkaran S. Sarohia Adrian K. James Chapter 1: Introduction1 1.1 Overview of the Biodiesel production process Biodiesel has been used as an alternative energy source for the major part of the 20th century. It offers unique advantages as a fuel, with low sulphur content, emissions with lower particulate matter, and reduced greenhouse gas emissions over its life cycle. In particular, replacement o f conventional fuels with biodiesel significantly reduces emissions such as CO2 , CO, SOx, volatile organic compounds (VOCs), unbumed hydrocarbons, and particulate matter (Ozil et al. 2009; Pisupati and Bhalla 2008). Biodiesel is a biodegradable, non-toxic and environmentally friendly product, which may be blended with fossil based diesel fuel in any proportion to create a stable, useful fuel blend (Pinzi et al. 2009). Biodiesel has a higher flash point than conventional petroleum diesel and is safer to store, handle and transport (Morais et al. 2010). Because it possesses the properties of blending with conventional fuels, biodiesel has received great amount of scientific and social attention. It has been promoted by policy makers and governments across the world, and its use in the transportation sector has been mandated in countries such as those in the EU-27 and other parts o f the developed world. To reduce Greenhouse Gas (GHG) emissions and promote a cleaner transport system, the European directive 2009/28/EC aims to achieve a 10% share of renewable energy in the transport sector by 2020 in EU (Redel-Macias et al. 2012). 1 Parts o f this chapter have been previously published: James, Adrian K.; Thring, Ronald W.; Helle, Steve; Ghuman, Harpuneet S. 2012. "Ash Management Review—Applications o f Biomass Bottom Ash." Energies 5, no. 10: 3856-3873. 1 Biodiesel is a mixture o f fatty acid alkyl esters commonly produced from triglycerides and alcohol through transesterification reaction in the presence o f alkali catalysts (Reed, Graboski, and Gaur 1992; Canakci and Van Gerpen 2001; Haas, Bloomer, and Scott 2002; Antolin et al. 2002; Haas 2005; Demirbas 2007). Feedstock for biodiesel is mainly food grade vegetable oils (S. Lee, Posarac, and Ellis 2011). Because food grade vegetable oils are in demand in industries such as food production, restaurants and also for domestic consumption their availability and cost competitiveness is a major challenge for large scale industrial use to manufacture biodiesel. The costs o f vegetable oils can be up to 75% of the total manufacturing cost, which makes biodiesel production costs approximately 1.5 times higher than those o f diesel (Haas, Bloomer, and Scott 2002; Phan and Phan 2008). Therefore, the industry is influenced by the high cost, and also the limited availability of feedstock for biodiesel production (Morais et al. 2010). Another important factor to be considered is the increase in consumption o f edible oils which has a direct impact on production and availability of feedstock for biodiesel production (Morais et al. 2010). According to United States Department of Agriculture (USDA), the net consumption o f edible oils in the top 15 countries and regions across the world will increase by 10.58 million metric tons between 2010 and 2013, which can be predicted from the past year trends in Figurel.l (USDA 2013). This growth is seen primarily in emerging economies o f China and India with approximately 9.7% and 11.7% increase in domestic consumption in the 3 year period, respectively. Similarly the United States shows an increase in domestic consumption, with an increase o f 11.8% from 2010 to 2013 (USDA 2013). China and the EU-27 remain the largest consumers o f edible oils 2 with estimates for 2012-13 pegged at 30.4 and 23.6 million metric tons respectively (USDA 2013). India and United States follow with consumption o f 17.9 and 13 million metric tons, respectively for the same timeline. This increase in consumption of edible oils casts some doubt on the availability and the cost-competitiveness o f feedstock such as refined vegetable oils in the near fixture. In the fixture, refined vegetable oils will have competing consumption patterns that will directly influence the cost o f feedstock for production o f biodiesel. It is evident from these developments that refined vegetable oils and similar agricultural products will be in high demand, both for hxxman consumption, and for energy production. The percentage of vegetable oils used for food has steadily declined from 86% in 2002-2003 to about 74% in 2011-12, but it still remains the major application for using these vegetable oils (USDA 2013). It may be interesting to point out that the worldwide consxxmption of vegetable oil for food uses in 2002-03 was 83.1 million metric tons and it rose to about 114.2 million metric tons in 2011-12 (USDA 2013), and the net world vegetable oil production for 2001-2012 is shown in Figure 1.1. The overall share o f food based applications is declining but the competition between food uses, industrial uses and energy production will only intensify in the fixtxxre (USDA, 2013). 3 ■ Olive oil ■ Coconut oil ■ Palm kernel oil ■ C ottonseed oil ■ Peanut oil ■ Sunflow erseed oil ■ Rape seed Oil ■ Palm oil ■ Soybean Oil « 140 jg 100 Q- 60 2002 2003 2004 2005 2006 2007 2008 2009 Year Figure 1.1. World Vegetable oil production, 2002-2012. Source: USDA 2013 4 2010 2011 2012 1.1.1 Waste feedstock for Biofuel production Biofuels from edible crops are not a long term solution. They do not have the potential to provide more than 10% o f liquid fuel demand in developed economies (Huber and Dale 2009). The EU directive (2009/30/CE) states that GHG emission savings for biodiesel made from conventional feedstock such as refined vegetable oil is about 50% and this value increases to over 80% for waste vegetable oil, animal fats and other waste products which can be converted to biodiesel (European Commission 2013; Morales et al. 2011). The Renewable Energy Directive (RED) and article 17 o f the EU directive also expresses support for promotion of renewable energies which are directly related to standards of sustainable biomass (European Commission, 2011). The RED specifically discourages the use of raw material which is cultivated on land which was previously a high carbon stock or o f a high biodiversity value. The European Commission (EC) also encourages diversification of raw materials used for bio-fuel production and inclines towards biofuels from wastes, agricultural residues, lingo-cellulose and other such feedstock. These are healthy developments, both for the environment as well as for communities actively engaged in reducing their GHG emissions. Waste feedstocks are inexpensive materials with potential to be converted to biofuels. Because they are the by-products o f industries or commercial operations, the most probable alternate fate for these wastes is disposal, landfilling or chemical treatment and refining. 5 Common wastes of vegetable origin are waste vegetable oils produced in restaurants. Other wastes o f high free fatty acid (FFA) content are yellow grease, brown grease (Canakci and Van Gerpen 2001), chicken fat (Amaud et al. 2006; K.-T. Lee and Foglia 2000), animal tallow (Oner and Altun 2009) etc.. The use of waste cooking oil (WCO) as a feedstock serves two purposes. It aids in decreasing the environmental impacts and costs of waste disposal and also reduces the production cost o f biodiesel (Meng, Chen, and Wang 2008; Phan and Phan 2008). WCO has some amount o f water and FFA which direct the conventional alkali catalyzed process to undesirable saponification. Using the conventional method, it is also difficult to remove the base catalysts after a reaction, and large amount of wastewater is produced during separation, cleaning o f catalyst and products (Shu et al. 2010). In 2004, the International Energy Agency (IEA) reported 2.63 billion pounds (1,192,947 tons) yearly average yellow grease production from 1993-1998 for the USA. This figure was sufficient to produce 344 million gallons per year o f biodiesel, but only 100 million gallons per year could realistically be manufactured due to technological and economic limitations (IEA, 2004). Comparing these figures with the USDA figures for vegetable oil used for food purposes, we may establish an estimated percentage about WCO and yellow grease production related to vegetable oil consumed. The national food purpose vegetable oil consumption for 1993-1998 was 7,931,000 tons average per year (USDA 2013). The figures point to an approximate 15% yellow grease production from vegetable oil used for food purposes. To understand the situation better, we must consider that domestic households generate waste that is not collected, and does not contribute directly to available WCO or yellow grease. Commercial operations like restaurants, deep frying 6 food manufacturing facilities, food processing industries use a more consolidated waste collection system, and contribute largely to this figure. If community waste collection programs are enforced, we may optimistically assume that this figure might likely double. Hence for the basis o f further estimates, a range o f 15% as the lower limit and 30% as the upper limit are established for calculations. Table 1.1 shows top 5 vegetable oil consuming countries and regions, and the amount o f WCO and yellow grease that may potentially be generated for a range o f 15%-30% o f total vegetable oil consumed for food purposes. We may also estimate the potential for biodiesel production from these figures. 7 Table 1.1. Vegetable oil consumption (for food purposes) in top 5 regions o f the world averaged from 2010/11 - 2011/12. Estimates of WCO produced within a range o f 15%30% from this consumed oil, and the potential for biodiesel production from the same. Potential biodiesel produced from (a) Potential biodiesel produced from (b) 7758 1118.5 2237.1 2396.2 4792.4 691 1381.9 12457 1868.6 3737.1 538.8 1077.6 10116 1517.4 3034.8 437.5 875.1 5091 763.7 1527.3 220.2 440.4 'Waste produced Country Vegetable oil consumed* (a) 2Waste produced (b) China 25860 3879 India 15974.5 EU-27 United States of America Indonesia * for domestic food use, in 103 tons averaged for 2010/11 - 2011/12.(USDA 2013) 1 Using 15%, in 103 tons. 2 Using 30%, in 103 tons. 3, 4 In 106 gallons (each ton of waste producing 288.4 gallons biodiesel, {IEA, 2004) 8 1.1.2 Catalysts for biodiesel production from waste feedstock The free fatty acid (FFA) and other impurities in WCO and other high fat wastes render the conventional alkali catalyzed biodiesel synthesis process open to saponification and gel formation that decreases the economy and yield, and increases the product separation and purification costs. The presence of water drives the reaction to an undesirable hydrolysis of esters and saponification. Commercial biodiesel operations usually employ a basic catalyst which is soluble in nature, like potassium or sodium methoxide. These operations also have an acid based pre-treatment step that esterifies the FFA if feedstock is not regulated for <1% FFA content (Santacesaria et al. 2007). Consequently, these homogenous acid and base catalysts are corrosive to process equipment in particular and pose a risk to fuel engines if not removed at the end o f production. Their removal by aqueous quenching and neutralization is both energy and cost intensive and it directly increases the cost of production in a biodiesel processing facility. It also contributes to emulsions and gel formations in the product (Demirbas 2007). This section reviews some recently studied processes and their key features in processing waste feedstock and waste streams. Shu et al. (2010) used a carbon based solid acid catalyst to synthesize biodiesel from a high FFA content WCO. Simultaneous esterification and transesterification gave triglyceride conversion o f 80.5 wt % and FFA conversion of 94.8%. Alptekin and Canacki (2011) used chicken fat as the waste feedstock and used an alkaline catalyst to obtain 88.5% ester yield after pre-treatment o f the feedstock with H2SO4 to convert the 9 FFA content and reduce its interference with the alkaline catalyst. Noshadi, Amin, and Pamas (2012) used a heteropolyacid catalyst in a reactive distillation column to achieve a FAME yield of 93.9%. This reaction was a continuous operation with a methanol excess o f 70:1, using 12-tungstophosphoric acid as a catalyst in a pilot scale plant. The feedstock was o f low moisture content, o f about 1% and the WCO had an acid value of 7.45 mg KOH/gm. The WCO was collected from domestic consumers and not commercial operations like restaurants or deep frying facilities. Guzatto et al. (2012) established that ethanol as a solvent in a transesterification double step process eliminates the need for anhydrous materials, low FFA content in feedstock and also deals with problems o f emulsions and saponification that are experienced with using methanol. They obtained a high yield o f Fatty Acid Ethyl Esters (FAEE), about 97% but also stated that the double step transesterification required longer reaction times and larger alcohol and catalyst amounts. Toba et al. (2011) successfully applied a hydrodeoxygenation process to convert WCO, trap grease from industry to paraffins and iso-paraffins. They upgraded all these source wastes with Nickel-Molybdenum, Nickel-Tungsten and Cobalt-Molybdenum based catalysts with a solid acid B2O3-AI2O3 support, to achieve complete conversion at temperatures 300 °C - 350 °C. Corro et al. 2012 used zinc filings as catalyst and a setup to harness solar energy for the reaction’s temperature control and produced biodiesel from non edible jatropha curcas oil. This process was again a two step process, the first step using the zinc catalyst to esterify the FFA and then using an alkali catalyst to transesterify the triglycerides to achieve 98% conversion using a 20% loading of zinc 10 filings. Alptekin, Canakci, and Sanli (2012) investigated the conversion potential o f leather industry waste as biodiesel feedstock. They used animal fat from leather industry waste and pretreated it with sulphuric acid and methanol to first convert the FFA, followed by alkaline catalysts for transesterification. The study achieved a greater than 90% conversion for the two step process using fleshing oil as a feedstock, which is a waste produced by the leather industry and has an FFA content o f 5-25% (Canakci and Van Gerpen 2001). Bezergianni et al. 2011 used hydrotreatment o f WCO as a process and optimized the Liquid Hourly Space Velocity (LHSV), H2/oil ratio and pressure on a small scale pilot plant. They reported their results with using a Nickel-Molybdenum type industrial hydro treating catalyst, and obtained an 82% biodiesel conversion. Morales et al. 2011 investigated the effects of impurities in WCO on sulfonic acid catalysts, and conversion of WCO to biodiesel using various catalysts. The yield with SBA-15 catalyst provided highest yields o f 80% using an 8% catalyst and 30:1 methanol excess. They also stated that the catalyst was strongly deactivated due to strong interactions of unsaponifiable matter and impurities with the catalyst sites. Ramachandran et al. 2011 also used a heterogenous aluminium based sulphated catalyst, A 1(HS 0 4 ) 3 to convert WCO to methyl esters. They observed a conversion o f 81% with an alcohol excess o f 16:1 and 220 °C as the reaction temperature. Lei et al. (2011) used low quality rice bran waste and converted the FFA to FAEE using an in-situ process with an esterification yield of 98% and transesterification yield o f 83%. The FFA content o f the waste was reported at 73-80%, and the waste was a by product o f a rice processing plant. Rice husk ash was applied by Manique et al. 2012 to purify biodiesel made from WCO. Azcan and Yilmaz 2013 used a microwave transesterification process with sodium 11 methoxide as the catalyst, followed by molecular distillation to purify the product. The feedstock was WCO supplied from a local food facility. Molecular distillation was employed to separate and purify the products to avoid problems o f toxicity and use of solvents for separation (Jiang et al. 2006; Martins et al. 2006). Al-Hamamre et al. 2012 used oil from spent coffee grounds and converted the FFA to FAME using a base catalyzed process. It is evident that recent research and scientific endeavour has shifted to explore alternative sources of feedstock to ensure that biodiesel production is cost-effective, and has a minimal effect on the environment. Table 1.2 presents various aspects o f some more research studies focused on employing waste feedstock, such as the type o f catalyst, reaction conditions and nature of products obtained. The Table 1.2 is shown to draw attention to the heterogeneous catalysts and waste streams, and their proportions and reaction conditions used. 12 Table 1.2. B rief summary o f recent research on using waste feedstock to produce biodiesel. The table depicts the type o f feedstock and catalyst, along with best yields and corresponding reaction conditions. Nature of feedstock Waste cooking oil Type of catalyst Heterogeneous Potassium supported pumice Reported Reaction conditions 20 wt% catalyst, 21:1 Methanol excess, Reaction time o f 4 hours(h), 60°C 5 wt% catalyst, 6:1 Methanol excess, 7h, 200°C 3.5 wt% catalyst, 15:1 Methanol excess, 5h, 150°C Type of product 90% FAME yield (Borges et al. 2011) Brown grease Heterogeneous Metal oxideZirconia catalyst Waste cooking palm oil Heterogeneous Clay based catalyst Waste cooking oil Barium meliorated waste marble as Heterogeneous basic catalyst 3.0 wt% catalyst, 9:1 Methanol excess, 3h, 65°C 88% FAME yield (Balakrishnan, Olutoye, and Hameed 2013) Functionalised porous carbonaceous materials 3.0 wt% catalyst, 32:1 Methanol excess, 6 h, 80°C 98 mol% FAME yield (Arancon et al. 2011) Metakaolinite clay mineral 3.0 wt% catalyst, 23:1 Methanol excess, 4 h, 160°C 95% FAME yield (Ramirez-Ortiz, Martinez, and Flores 2012) High FFA content oil Waste cooking oil 13 >97% FAME yield (Kim et al. 2011) 96% FAME yield (Olutoye and Hameed 2013) 1.1.3 Environmental and Economic Benefits of using waste feedstock Biodiesel is an attractive substitute for use in diesel fuel based energy operations. One of the major challenges facing biodiesel production under current conditions is the cost competitiveness with fossil fuels and other fuel substitutes. The main external costs savings of biodiesel come from the reduction in depletion of fossil energy resources, and the mitigation of CO 2 emissions. Also, combining external and internal costs, B5 and BIO biodiesel blends are competitive to diesel on a per kilometre distance driven basis (Silalertruksa, Bonnet, and Gheewala 2012). Biodiesel combustion produces reduced particulate matter, hydrocarbons, carbon monoxide, sulphur oxide and poly aromatic hydrocarbons (PAH’s) when compared to fossil fuel combustion (Lin, Hsu, and Chen 2011). One study used a public transit bus in Denver, Colorado to demonstrate that biodiesel blends reduce smoke opacity by almost 60% without any loss in power delivered by the engine (Reed, Graboski, and Gaur 1992). WCO based biodiesel emissions have been reported to have reduced content of particulate matter, hydrocarbons, PAH’s and carbon monoxide (Antolin et al. 2002; Lin et al. 2006; Tsolakis et al. 2007). Haas et al. (2002) found that 88% o f the costs in biodiesel production were associated with feedstock acquisition. The total costs of biodiesel are slightly higher than diesel (Van Gerpen et al. 2004) but the benefits of CO 2 emission reductions along with environmental benefits help justify the slightly increased costs. The use o f biodiesel and its production has other social benefits such as stabilization of farmer’s income and employment generation, as well as reduction of the country’s dependence on oil imports 14 leading to improved energy security and lesser economic dependence on oil exporting countries (Silalertruksa, Bonnet, and Gheewala 2012). Using waste feedstock is a direct way to economize and reduce waste disposal costs and it helps produce a useful product from an otherwise obsolete material. Community programs for waste collection such as Trap the Grease implemented by the city o f Tulsa, Oklahoma demonstrate that waste grease and associated types o f domestic wastes are a significant cost in waste water treatment and maintenance o f sewer systems. The initiative to collect them at source may not only offset these costs, but may also create potential to convert these wastes into upgraded and useful products such as bio-diesel with relative ease and efficiency. 1.1.4 Summary and Conclusions Biodiesel is increasingly being recognised by industry and governments as an attractive alternate to reduce their net emissions. A brief summary o f the policies influencing biodiesel production are reviewed in this section. These policies are the ones that directly impact availability and choice o f feedstock, or promote the use o f alternate fuels, in particular biodiesel. In recent years, mandates for blending have been implemented in countries all over the world. The United States o f America mandated targets (RFS-2) for national consumption of biomass based biodiesel at 0.65 billion gallons in 2010, about 1.1 % of total diesel sales for that year. The focus in this initiative was also laid on accounting for emissions from 15 indirect land use changes (ILUC) when measuring the GHG reductions by using biodiesel. Lifecycle emissions according to this standard must account for a 50% reduction as compared to petroleum diesel for it to be considered sustainable. According to these RFS-2 standards, waste oils, fats and greases all comply with this requirement. Argentina has a mandate o f 7% biodiesel blending as o f August 2010. ILUC are a major concern when dealing with biofuels production, and increasing land use changes may decrease the environmental benefits offered by biofuels. Similar concerns were expressed by the European Union commission, and countries such as Germany, France and Netherlands speak in favour of certified sustainability criteria which may help determine the actual benefits o f biofuels depending upon the source o f feedstock and efficiency o f production. In February 2011, Canada mandated a 2% blending o f biodiesel with conventional diesel fuel across the country. The Chinese government in 2011 limited the use of all grains and edible oils for biofuel, alcohol or other non food applications, citing the aim to protect supplies of products for human and animal consumption. The European Union introduced the requirement for proof o f sustainable production methods in the same year. The European Commission introduced seven voluntary certification schemes, aimed at evaluating and certifying the sustainable aspects o f various bio fuels that are produced or consumed in the EU. As recent as May 2012, the EU was struggling to formulate concrete regulations to measure ILUC factored emissions for vegetable oil based bio fuels. Recent research carried out for the EU suggests that vegetable oil based biodiesel has higher GHG emissions if ILUC factors are considered. 16 Global developments and increasing concerns about land use changes, loss o f biodiversity and food crisis has impacted the production o f biodiesel from vegetable oil sources. This is reflected in the rapidly changing policies, reduction o f subsidies and including of sustainability criteria in measuring the emission reductions and true environmental benefit o f a renewable energy source. These influences are also observed in government action and decision making as regards to the biodiesel and renewable fuel sector. Waste feedstock such as waste cooking oil, animal fats, plant residue, leather waste, vegetable oil refinery waste have consistently exceeded and met these sustainability criteria. This is mainly because waste products are o f low value, have been produced on completion of their primary purpose, and their alternate fate is landfilling or disposal. New technologies and processes to refine this waste feedstock have been evaluated in this chapter. It is imperative that the scientific focus be shifted to the feasibility o f using waste feedstock in the production o f renewable fuels especially biodiesel. The wide acceptance for biodiesel as a diesel fuel substitute and blend is evident from its global demand and production. The optimization o f a process to balance the economic and environmental benefit in a sustainable manner is extremely important. The use of waste feedstock has driven us in the right direction, o f minimizing waste disposal costs and upgrading low value wastes into high value products of both economic and environmental significance. 17 1.2 Biomass to energy In recent years, technologies to harness energy from biomass have come to be widely used and accepted in a wide range o f energy generation processes. District power and heating programs in Scandinavian countries, and utilization o f biomass in co-combustion o f coal in the Netherlands are such examples (Hoogwijk et al. 2005; Turkenburg 2000). Studies estimate the future contribution o f biomass based energy to account for almost 15% - 25% of the worlds energy needs (Bemdes, Hoogwijk, and van den Broek 2003; Hoogwijk et al. 2005). Investigations are also aimed at reviewing the potential of biomass to energy operations based on factors such as source feedstock, energy demand and supply, land use policy, population growth patterns and evolving technologies (Thran et al. 2010; Batidzirai, Smeets, and Faaij 2012). Modem technologies to harness bioenergy are increasingly efficient and clean, contributing to the rising popularity and immense future potential o f bioenergy obtained from renewable biomass (Hall 1997; Hall and Scrase 1998). The technologies are mostly thermo chemical processes that produce useful energy from biomass. They employ novel techniques such as combustion, gasification, pyrolysis and liquefaction to produce energy or liquid and gaseous fuels with a higher heating value (Oktay 2006; Suarez, Beaton, and Zanzi 2006). In a unique initiative in 2009, the University of Northern British Columbia, Canada installed a 1.5 GJ/hr pellet boiler to heat the enhanced forestry laboratory using locally produced wood pellets. Combustion produces direct heat from biomass by rapid heating 18 in an oxygen rich environment (Fryda et al. 2006; Bridgwater 2012). Pellet burners are devices used to achieve complete combustion o f wood pellets to maximize energy output from biomass. Use o f wood pellets for heating provides possibilities o f more automated and optimized systems, with higher combustion efficiency and less products of incomplete combustion compared to traditional wood log firing (Ohman et al. 2004). Pelletized wood is more convenient than wood residue because it is energy dense, it can be easily stored and transported, and can be used in automated energy systems much like liquid fuels (Park et al. 2012). More than 2/3 o f the annual pellet production o f Canada comes from facilities located in British Columbia, specifically located closer to Prince George where these resources are found in close proximity (Magelli et al. 2009). The UNBC on-campus pellet boiler facility consumes approximately 150 tonnes/year o f locally produced wood pellets to achieve a >90% fuel conversion efficiency. This entire setup offsets approximately 130 tons/year o f fossil fuel CO 2 , and consists of 400 kW pellet boiler accompanied with a 2500 L heat storage tank and a 50 ton fuel storage hopper. The 1.4 GJ/h KOB Pyrot rotary combustion pellet burner consumes 11 tonnes/month o f pellets, generating 23 kg/month bottom ash and approximately 0.4 kg/month o f fly ash. The bottom ash is collected from the bottom grate of the burner, while the fly ash is trapped in filters used to remove particulate matter from exhaust streams. The wood pellets are supplied by Wood Pellet Association of Canada and are produced primarily from softwood sawmill waste. The wood chips have varying ash content based on the bark content of the mixture. This is because the minerals are usually more concentrated in the bark region (James et al. 2012). 19 A gasification system has also been operational since January 2011 at the campus o f University o f Northern British Columbia to harness energy from sawmill residue such as shavings, sawdust, chips etc from local mills. Gasification is the controlled heating o f biomass in oxygen deficient, reducing conditions to produce producer gas (Malkow 2004; Bridgwater 2012). Fuel gas that is produced may be combusted in a conventional burner, connected to a boiler and a steam turbine, or in a more efficient energy conversion device, such as gas reciprocating engines or gas turbines (Arena 2012). The gasification system is a reducing environment gasifier located on campus at the University of Northern British Columbia, Prince George, Canada. The biomass gasification system uses wood residues or other clean residues to produce energy in an oxygen deficient environment. The gasifier has a diameter o f 4.3 meters and the accompanying flue gas boiler has a capacity of 4.4 MW. The plant based on biomass gasification has an energy output o f 16 GJ/h and offsets approximately 85% of the campus heating needs. It also reduces CO 2 emissions, registering a decrease of 3500 tonnes annually when compared to using fossil fuels for the equivalent energy production. These initiatives are relevant in a socio-economic setup which is rapidly shifting towards more sustainable practices. The prime focus is to supplement current energy production and provide cleaner sources o f energy that are renewable and environment friendly. The initiatives reflect the exponentially growing sectors o f bioenergy and their appeal to a large section of the world’s developed nations, united in their common goal of lowering CO 2 emissions. These steps to reduce pollutants are consistent with various international pollution and emission control agreements and objectives and goals outlined by the Inter­ 20 governmental Panel on Climate Change (IPCC). While bioenergy continues to rise in popularity and market value, there are particular concerns that arise from current practices. An example of these is land use change and its effect on the environment along with including it in sustainability accounting. O f particular concern in biomass to bioenergy operations is the generation o f residues. Most processes produce an ash residue rich in inorganic content in varying volumes depending upon feedstock, type o f process, operating conditions and process efficiency. 1.2.2 Ash production and utilization Ash is the incombustible part o f wood fuel and biomass left after complete combustion, and contains the bulk of the mineral fraction (Khan et al. 2009). The ash containing part is an integral component o f the plant structure and consists o f a wide range o f elements (Quaark, Knoef, and Stassen 1999). The ash content varies from less than 2% for wood, to about 5%-10% for crop residues and 30% - 40% for rice husks, milfoil (Quaark, Knoef, and Stassen 1999). Ash is produced upon the thermochemical degradation of biomass based products such as sawdust, shavings, wood pellets etc. Finer ash particles are trapped in filters, precipitators and comprise the fly ash fraction of the ash. Coarser and larger particles are collected as bottom ash. These types o f ash vary in properties due to the difference in feedstock biomass, operating process and conditions and system efficiency. High ash content significantly reduces the energy output derived from that biomass source (James et. al, 2012). The current scenario o f ash production, and future 21 potential may be estimated by assessing the amount o f woody biomass available for energy operations. Wood residue forms a significant input for energy uses such as in gasification, pyrolysis and combustion. The Food and Agriculture Organization (FAO) describes wood residue as by products which have not been reduced to small pieces. This consists of industrial generated wood wastes such as sawmill rejects, slabs, edgings and trimmings, veneer log cores, veneer rejects, sawdust, bark (excluding briquettes), residues from carpentry and joinery production etc. Residues produced at industrial processing sites such as bark and sawdust from sawmills are the largest commercially used biomass source (Thran and Kaltschmitt 2002). According to the Food and Agriculture Organization (FAOSTAT), approximately 98.2 x l0 7m3 o f wood residue was generated globally, as a yearly average from 1992 to 2010. In this period, the top five wood residue generating countries were China, B razil, United States o f America the Russian federation and France which can be seen in Table 1.3. These residues have potential in the near future to supplement growing demands from wood and biomass based energy. The coniferous wood fuel used is a good means to estimate current ash generation. The top five users o f coniferous wood fuel in the year 2010 were United States o f America, China , B razil, Russian federation and France which may be seen in Table 1.3 . The bulk density o f residual woody biomass varies for different categories. Some o f these varieties of residues are hardwood chips (0.23 ton/m3), softwood chips (0.18-0.19 ton/m3), sawdust (0.12 ton/m3) and planer shavings (0.10 ton/m3) (McKendry 2002). The approximate bulk density of wood residue is considered equivalent to 0.16 ton/m3, and for wood fuel this is estimated at 0.21 ton/m3. The product of the bulk density (ton/m3) and amount o f wood fuel (m3) gives us an estimate o f the mass o f wood currently used in ash generating 22 processes. Similar calculation of product of bulk density (ton/m3) o f wood residue and amount of wood residue (m3) generated can give us an approximation of the wood residue for potential use in energy processes, which has been done in the last two columns o f Table 1.3. The ash content o f wood varies widely depending upon the type o f wood. Clean wood without bark (<1%), bark (3%-4%), contaminated bark (5%-15%), contaminated reject wood (0.5%-19%), clean reject wood (0.5%-3%) are some examples o f varying ash content. The ash is fixed at 10% (dry basis) for wood fuel, to account for inefficiencies in the variety of processes used, and 15% for wood residue to accommodate contaminated feedstock and mineral rich parts such as contaminated bark etc. Table 1.3: Estimate of potential ranges of net ash production based on complete wood residue utilization in global leaders o f wood residue generation, and complete wood fuel utilization (FAOSTAT, 2012) Country China Brazil United States o f America Russian federation France Wood residue Wood fuel Ash from wood Ash from wood (107 m3) (107m3) residue (106tons) fuel (106tons) 15.3 14 13 91 13 9.5 2.45 2.24 2.1 28.7 4.1 3.0 7.9 19 1.3 6.0 7.7 2.7 1.2 0.9 23 The European Union produced 56 x 106 tons o f ash in 2005, and this is expected to double by 2020, leading to an estimated 155 x 106 tons o f ash in the EU-27 (Obemberger and Supancic 2009). Our estimate for the 140 x 107 m3 of fuel wood produced in the region puts the ash generation at 44.1 x 106tons o f ash. The imports o f fuel wood and pellets, industrial utilization o f wood residues are not included in our estimate as these parameters vary from country to country and over time as well. An accurate calculation is difficult to determine and may only be achieved by monitoring ash generation processes and measuring the final generated ash quantities. The current use compared to potential varies from 12% in Latin America, 16% in North America, 22% in Europe and 108% in Asia (Thran and Kaltschmitt 2002; Thran et al. 2010). There is immense potential for developing biomass to bioenergy technologies in countries in North America and Europe (Parikka 2004). These figures will likely rise in the future which will be accompanied by an increase in total ash generation. The alternate fate for majority o f wood residues not being used for power generation is landfill or disposal (Morris 1999). Some alternative applications for these biomass ashes have been suggested by recent scientific studies. Agricultural and construction use are two main applications that have been studied (Holt and Raivio 2005; Holt and Raivio 2006; Gomez-Barea et al. 2009; Rajamma et al. 2009; Cheah and Ramli 2011). With the increased use o f biomass to produce energy, the ash and residue volumes will increase in the future. Major challenges will arise relating to the efficient management o f these products (James et al. 2011). 24 The alternate useful utilization of these wastes as catalysts in bio-diesel production is the focus of this thesis and discussed in the following chapters. Residues from previously described biomass to energy operations were collected, characterized and prepared as catalysts for use in a chemical process. The transesterification o f WCO was done using the catalyst to demonstrate the process utility o f the inorganic content in ash. The catalytic activity was tested in a batch process over a set o f different temperatures to evaluate the highest yields possibly achieved by the two catalysts. 25 CHAPTER 2: Pellet burner bottom ash as a heterogeneous catalyst for fatty acid methyl ester production 2.1 Introduction Biodiesel is defined as a mixture of fatty acid alkyl esters which are commonly produced from triglycerides and alcohol through transesterification reaction in the presence o f alkali-catalysts. Methanol is the most widely used alcohol; and the resulting esters are known as fatty acid methyl esters (FAME). Feedstock for biodiesel is mainly food grade vegetable oils (Lee, Posarac, and Ellis 2011). The costs o f these vegetable oils can be up to 75% of the total manufacturing cost, which makes biodiesel production cost approximately 1.5 times higher than those o f conventional diesel (Haas, Bloomer, and Scott 2002; Phan and Phan 2008). Therefore, the biodiesel industry is influenced by the high cost, and limited availability o f vegetable oil for biodiesel production (Morais et al. 2010). Also, biofuels from edible crops are not a long term solution as they do not have the potential to provide more than 10% o f liquid fuel demand in developed economies (Huber and Dale 2009). The EU directive (2009/30/CE) states that Green House Gas emission savings for biodiesel made from conventional feedstock such as refined vegetable oil is about 50% and the value increases to over 80% for waste vegetable oil, animal fats and other waste products that may potentially be converted to biodiesel (Morales et al. 2011; European Comission 2013). Common wastes o f vegetable origin are waste vegetable oils produced in restaurants. Other wastes o f high Free Fatty Acid (FFA) content include yellow grease, brown grease (Canakci and Van Gerpen 2001), chicken fat ( Lee and Foglia 2000; Amaud et al. 2006) and animal tallow (Oner and Altun 2009). The 26 use of waste cooking oil (WCO) as a feedstock serves to decrease the environmental impacts and costs o f waste disposal and decreases the production cost of biodiesel significantly (Canakci and Van Gerpen 2001; Meng, Chen, and Wang 2008). WCO has some amount of water and FFA which direct the conventional alkali catalyzed process to undesirable saponification. Using the conventional method also makes it difficult to remove the base catalysts after a reaction, and large amount o f wastewater is produced in separation and cleaning of catalyst and products (Shu et al. 2010). FFA impurities in WCO and other high fat wastes render the conventional alkali catalyzed biodiesel synthesis process open to saponification and gel formation that decreases the economy and yield, and increases and increases the product separation and purification costs (Santacesaria et al. 2007). The presence o f water drives the reaction to an undesirable hydrolysis o f esters and saponification. Commercial biodiesel operations usually employ a basic catalyst which is soluble in nature, like potassium or sodium methoxide. These operations also have an acid based pre-treatment step that esterifies the FFA if feedstock is not regulated for <1% FFA content (Santacesaria et al. 2007). Consequently, these homogenous acid and base catalysts are corrosive to process equipment in particular and pose a risk to fuel engines if not removed at the end of production. Their removal by aqueous quenching and neutralization is both energy and cost intensive and it directly increases the cost o f production in a biodiesel processing facility. It also contributes to emulsions and gel formations in the product (Demirbas 2007). The near future requires economic growth with sustainable environmental benefits from the use of low cost renewable energy sources (Grammelis et al. 2006; B-M. Steenari, Karlsson, and Lindqvist 1999). The increased shift to biomass use for energy may 27 potentially generate upwards of 400 million tonnes o f ash. The ash is harmful if not properly disposed. Such concerns arise from findings that nutrients largely considered useful for land application are unavailable as they are water insoluble, but dangerous trace elements such as As, Bi, Cd, Co, Hg, Mn, Se, Pb and V are present in water soluble forms (Obemberger et al. 1997; Narodoslawsky and Obemberger 1996; Callesen, Ingerslev, and Raulund-Rasmussen 2007; Reimann et al. 2008). There is a high probability of large quantities of ash becoming a source o f heavy and toxic metals especially during storage and disposal or application to soils (George, Dugwell, and Kandiyoti 2007; Gogebakan and Selpuk 2009; Llorente et al. 2006; Meij and te Winkel 2007; Vamvuka, Zografos, and Alevizos 2008; Pandey, Abhilash, and Singh 2009). In the light of these findings, the proper disposal and useful utilization of this waste is very important (Vassilev et al. 2013a; Loo and Koppejan 2008; Obemberger, Brunner, and Bamthaler 2006). Alternate uses of ash such as application to chemical processes are yet to be explored. The production of FAME from oil via transesterification is a well studied process, as previously mentioned. The yield of the transesterification reaction is estimated by techniques such as gas chromatography, infrared spectroscopy, gel permeation and 'HNMR among others. In recent years, various studies have focused on using ’H-NMR to monitor the transesterification reaction progress, kinetics and FAME yield among other parameters (Gelbard et al. 1995; Gerhard Knothe 2000; Suppes et al. 2001; Neto et al. 2004; Morgenstem et al. 2006; F. Jin et al. 2007; Ghesti et al. 2007; Cabefa et al. 2011; Anderson and Franz 2012). High-resolution NMR is fast compared to conventional analytical techniques for assessing FAME yields, such as chromatographic (GC), or gel 28 permeation methods. Also, it is easily adapted in routine process analysis, and allows non destructive measurements o f the samples (G. Knothe 2001). High-resolution 'H NMR spectroscopy has been used to monitor the transesterification reaction (Cabega et al. 2011), based on the areas of the methoxy signal at 3.7 ppm, the a-carbonyl methylene signal at 2.3 ppm (Morgenstem et al. 2006), and the areas o f the glycerides signal from 4.04 to 4.25 ppm (Ghesti et al. 2007). There are different formulae suggested in various studies to estimate the progress of reactions (Gelbard et al. 1995; Knothe 2000; Morgenstem et al. 2006; Anderson and Franz 2012). There seems to be a consensus among studies (Morgenstem et al. 2006; Cabefa et al. 2011; Anderson and Franz 2012) that the formula suggested by Knothe (2000) had incorrectly assigned five protons to the glyceryl methylenes in the range 4.104.33 ppm. The equation put forth by Gelbard et. al (1995) on the other hand is susceptible to interference at 2.31 ppm by FFA signals (Satyarthi, Srinivas, and Ratnasamy 2009; Anderson and Franz 2012). Recent studies (Morgenstem et al. 2006; Cabe9 a et al. 2011; Anderson and Franz 2012) have shifted to different assignments and formulae. The formulae listed below have varying integrations for different peaks o f the ’H- NMR spectra to arrive at the final yield o f the reaction, but the assignment o f the methyl signal is consistent across studies at approximately 3.70 ppm. C Knothe = x l 00 ME rGelbard - — — 9 1 TG xl00 31 nCHilI 29 21 rMorgensten = n r — Mqg t ME q Anderson ^ = — lm — j q t I M E + ^ I TM x io o OIL xioo The equation o f Anderson and Franz, is precise for high resolution 1H-NMR with accurate results from 400 Mhz and higher rated equipment (Anderson and Franz 2012). These high resolution techniques involve relatively expensive equipment which was not available. For the current work, the expression derived by Morgenstem et al. is used. This equation has recognized the incorrect integration by Knothe, and does not consider the 2.31 ppm integration either (Anderson and Franz 2012). It has also been used by Cabeca et al. to monitor the progress o f the reaction. The use o f pellet burner bottom ash as a heterogeneous catalyst for the production o f FAME using waste cooking oil in a batch reactor is presented. This chapter investigates the use of a heterogeneous catalyst made from pellet burner bottom ash to produce FAME from waste cooking oil, and its efficiency at different working temperatures. 30 2.2 Experimental 2.2.1 Materials and Methods Waste cooking oil was collected from both domestic and commercial cooking operations. The cooking oil was filtered using whatman (number 4) filter paper and mixed prior to use so as to ensure homogeneity of the sample. The ash (PBA) used in the experiment was obtained from a pellet burning facility that utilizes wood pellets, and is located in northern British Columbia, Canada. Methanol (> 95 %) was obtained from Fisher Scientific. Chloroform-d (> 98.9 %) with 0.03 % (v/v) TMS as internal standard for use as a solvent in the 'H-NMR analysis was purchased from Sigma Aldrich. ThermoScientific 7500 inductively coupled plasma with a mass spectrometer (ICP-MS) was used to evaluate the elements present in ash. The samples were microwave digested in a Milestone MLS 1200 Mega digestion system using concentrated nitric acid prior to ICP analysis. The X-ray diffraction (XRD) pattern for the ash (< 150 pm) after sieving and after treatment, were taken on a Bruker D8 Advance Series II to evaluate the different phases o f the inorganic content on a moisture free basis. The XRD was done using CuK al radiation at a wavelength of 1.5406 A with 2® being varied from 10° to 90°. The Scanning electron micrograph (SEM) was obtained on a Philips XL30 series microscope at an accelerating voltage o f 20.0 kV and 2500x magnification. The BET surface area was determined using a Micromeritics HS 112300 machine using a 30 % Nitrogen and 70 % Helium atmosphere at 77 K. Thermo gravimetric analysis (TGA) was done on a TG 50 instrument and 10 mg of sample. The temperature was increased at 10° C/min in Nitrogen 31 with a gas flow rate o f 20 mL/min. The sample was heated to a maximum temperature of 900 °C and held there for 5 minutes. 2.2.2 'H-NMR Method 'H-NMR spectra were obtained using a Bruker Fourier 300 MHz instrument. Solvent used was chloroform-d (CDCI3) with 0.03 % v/v Tetra Methyl Silane (TMS) and the number of scans was set at 32. The integrated intensities of the methyl peak were considered between 3.63 - 3.69 ppm chemical shift, and 4.25 - 4.35 ppm for the oil signal (Morgenstem et al. 2006; Cabe?a et al. 2011). A 'H-NMR sample was prepared by dissolving 10 pL o f each sample was dissolved in 800 pL of chloroform-d. 2.2.3 Catalyst Preparation The ash was sieved through a 150-pm sieve, and the fraction < 150 pm was used to prepare the catalyst. The <150 pm fraction was dried at 105 °C for three hours and subsequently heated in a muffle furnace to prepare the catalyst. The temperature was increased to 500 °C in 30 minutes, and then ramped up from 500 - 800 °C at a heating rate of 10 °C/ min, and then maintained at 800 °C for four hours. The catalyst was then stored in a desiccator until further use. 32 2.2.4 Experimental Procedure for transesterification A 300 mL EZE Seal reactor from Autoclave Engineers, USA was used for all the reactions. One hundred mL o f the Waste Cooking Oil (WCO), 12:1 molar ratio of methanol to oil and 5% (wt% o f oil) o f solid catalyst were added into the reactor. The reactor was pressurized with N 2 before starting the reaction to ensure that methanol remained in the liquid state at the different working temperatures, followed by turning on the heater and mixer. The ramp up rate was specific to each temperature and the heat-up time was ~ 20-25 minutes for each reaction. Samples were collected over different time intervals as soon as the heat source was introduced. A valve type liquid sample outlet was used to collect liquid samples o f ~1.5 mL each. The samples were collected in 2 mL borosilicate vials. The application of heat to the system and starting o f mixer was considered as zero minutes for all the reactions. These liquid samples were then analysed by 'H-NMR. 33 2.3 Results and Discussion 2.3.1 Catalyst Characterization The ash (PBA) was particularly rich in Calcium and Potassium (Table 2.1). The concentration o f Calcium was approximately 250 mg/g, and Potassium was 95 mg/g in the ash. Magnesium and Manganese were also present in relatively high concentrations, present in 50 mg/g and 26 mg/g o f ash respectively. The high concentration o f alkaline metals justifies the exploration of PBA as a catalyst for processes catalyzed by the metals and their carbonates and oxides. FAME production is a process that performs well with basic catalysts. The variation in particle sizes affects the physical and chemical properties displayed by the ash (Table 2.1). 34 Table 2.1: Elemental concentrations in ash and catalyst from the wood pellet burnerfo r the top six elements in decreasing order o f concentration as found by ICP-MS. Element Ash (As received) Ash (<150 Hm) (mg/kg) (mg/kg) PBA Catalyst Difference (mg/kg) Increase (mg/kg) (%) Calcium 246185 262727 16542 6.7 288735 Potassium 95231 95659 427 0.4 107087 Magnesium 50910 56532 5622 11.0 68158 Manganese 25845 28114 2269 8.7 33562 Aluminium 7688 7555 -133 -1.7 9412 Iron 6659 6168 -491 -7.4 5980 35 Figure 2.1: Scanning electron micrograph at 2500x magnification fo r Pellet burner ash after sieving through <150 pm 36 Figure 2.2: Scanning electron micrograph at 2500x magnification fo r PBA catalyst. t v io n (*] {C> - rwcNkfce - K 2 C « ( C 0 3 J 2 [5] (*) - C U tM H .S ./11- CaCClS • ] (C J - H o n c ia s e - M g ( J 11UUU S] (C ) - L im e - C a O 10000 7000 3 000 2000 1000 A 10 20 30 40 GO - ^ A. CO 2-Theta - Scale Figure 2 3 : X-ray diffraction pattern o f sieved ash (<150 pm) fo r 2 0 ( f to 7(f. The peak markers show the relation between experimental data and best fit patterns fo r the identified materials. 38 70 11000 a (C ) - L im e - C aO [j] o P ellet Burner A s h (P B A ) ra 2 70 - 60 - 50 0 100 2 0 0 3 00 4 0 0 500 600 7 0 0 800 9 0 0 100 0 T em p eratu re (C) Figure 2.7 TGA curves o f catalyst and ash at heating rate o f 10°C/ min. The mass losses in ash after 650° C are observed due to loss o f carbonates. 42 Figure 2.1 shows the SEM of the ash (< 150 pm), and catalyst after treatment. The post treatment image in Figure 2.2 displays layers o f solid in a well ordered arrangement. This may be explained as the formation of calcium oxide upon treatment, present as a uniform crystal system in the material. The earlier image consisting o f different metal carbonates has different phases; hence, the well ordered solid layers are absent. The XRD pattern obtained for PBA in Figure 2.3 is in good agreement with the ICP analysis. Calcium, Magnesium and Potassium are the major elements in the ICP analysis are also found by the co-relation o f the experimental XRD pattern to the reference database from the International Council of Diffraction Data (ICDD). The ash, as a waste product, is rich in inorganic content but sieving the ash improved the relative concentration o f calcium as may be seen from Table 2.1. Fairchildite and Calcite are found in wood ash, and are commonly known as wood ash stones (Milton and Axelrod, 1947). The presence o f Calcite, Periclase, Fairchildite and Calcium oxide is in agreement other similar studies done on XRD analysis of wood ash (Dawson and Sabina 1958) and specifically ash from biomass combustion (Steenari and Lindqvist 1997; Steenari, Karlsson, and Lindqvist 1999; Steenari and Lindqvist 1997). The FT-IR of the PBA displayed characteristic peaks at 500 cm '1, 875 cm '1, 1431 cm '1, 3440 cm '1 as seen in Figure 2.5. While the peaks at 880 cm'1 and 1400 cm '1- 1500 cm '1 are characteristic of CaCC>3 (Pouchert 1997; Kleiner et al. 2002), the other peaks at 500 cm '1 and 3400 cm '13500 cm '1 are attributed to MgO ( Jin et al. 2009; Xie et al. 2011). The PBA catalyst in Figure 2.6 displays peaks at 519 cm'1, 868 cm '1, 1051 cm'1, 116 cm '1, 1400 cm '1 and 3080 cm '1. The disappearance o f the carbonate peaks observed in the ash is indicative of loss of the carbonates. The formation of peak at 519 cm '1 is attributed to CaO (Granados et al. 43 2007) and MgO displays peaks at 1400-1600 cm '1 (Jin et al. 2009; Xie et al. 2011) and 1025 - 1100 cm '1 (Jin et al. 2009). Table 2.2: Semi-quantitative composition o f PBA and PBA catalyst as determined by XRD. Pellet Burner Ash (<150 pm) PBA Catalyst Mineral % Mineral % Lime, syn Periclase Fairchildite Calcite, syn 3.6 12.6 12.9 70.9 Calcium Silicate Lime Periclase Iron Manganese Silicate Hematite, syn 15.2 44.4 24.6 8.9 6.8 The concentration of alkaline metals such as Calcium, Potassium and Magnesium increased after sieving the ash (Table 2.1) Upon treatment, the mass loss in the range o f 700 - 900 °C, as seen in the TGA curve in Figure 2.7 were associated with the loss of carbonates of Calcium. The catalyst is a solid, formed after calcination of ash from biomass combustion operations. The BET surface area o f the catalyst was determined to be 2.75 m /g. The ash 44 (< 150 pm) was rich in calcite and related metal carbonates as may be seen in the XRD pattern in Figure 2.3. The phases identified by FT-IR are also in agreement with XRD results. The presence of carbonates in the ash, and oxides in the catalyst was observed by IR spectroscopy. After treatment, the XRD pattern also shows the presence o f oxides as may be seen in Figure 2.4. The calcination process gives a solid with approximately 44 % Calcium oxide, and 25 % Magnesium oxide as observed by XRD. The use o f these oxides in different forms for producing FAME has been studied (Kouzu et al. 2008; Xu et al. 2010; Diez et al. 2011; Olutoye and Hameed 2013). The presence o f these oxides in the solid calcined ash is useful in the application of this solid as a heterogeneous catalyst. 45 2.3.2 Reaction yield and catalyst perform ance The methyl peak is obtained at -3.70 ppm, and the solvent peak for methanol is observed at -3.50 ppm. TMS (0.03 % v/v) was used as an internal standard, and its peak was at 0 ppm chemical shift. The integrated intensities o f the methyl peaks and triacylglycerol (TAG) in all the samples were used to calculate the yield and progress o f reaction. Figure 2.8 shows the time based overlap of different spectra from 35 minutes to 95 minutes at specified reaction conditions. As the reaction progressed, the characteristic methyl peak increased in intensity. Figure 2.8 shows that the TAG signal at -4.25 ppm decreases in intensity relative to the characteristic methyl ester peak at -3.7 ppm, as the reaction proceeds. The TAG signal is employed for calculating the yield and is observed at 4.27 4.33 ppm as a doublet o f doublets. The overlap from intermediates such as di and monoglycerol may lead to incorrect yield calculations based on wrong integration of peaks (Anderson and Franz 2012). The multiplet of 1,2-diaclyglycerol at 4.17 - 4.29 ppm or doublet of doublets o f 1-monoacylglycerol at 4.15 - 4.25 ppm were not observed in the NMR. Figure 2.9 shows the 1H-NMR o f the samples at different times in the region of 4.0 - 4.5 ppm chemical shift. Figure 2.9(a) displays the region for sample collected after 35 minutes of reaction at 120 °C and Figure 2.9(b) displays the same region for the sample collected at 60 minutes of reaction at the same temperature. Interference or overlap from intermediates and other species were not observed, and the peaks of the TAG are the two doublet of doublets, ranging from 4.11 - 4.17 ppm and 4.27 - 4.35 ppm. 46 Normafized Intensity 1.0*; ml mA 0.6H 0 .5 -i 0.4-i Chemical Shift (ppm) Figure 2.8. Time based overlap !H-NMR o f samples fo r the reaction at 120°C, 12:1 Methanol to oil molar ratio and 5 wt% catalyst. 47 Normalized Intensity 0.30 0.25 0.05 5.5 i.ip r . r T in-r --.in C h e m ic a l Shift (ppm ) 4 - 5 5.0 4.5 4.0 C h e m i c a l S h ift ( p p m ) 4.0 (a) (b) Figure 2.9 : 1H-NMR region showing Triacylglycerol (TAG) as a doublet o f doublets with no overlap or interference by reaction intermediates fo r (a) 35 minutes and (b) 60 minutes o f reaction at 1 2 (f C. 48 The reaction yields at various temperatures are shown in Figure 2.10 - 2.12. The figures show that the reaction is temperature dependent. The lowest yield and rate of reaction were observed at temperature of 80 °C, seen in Figure 2.10. Approximately 25 % o f the reactants were converted after an extensive period o f 8 hours. At 160 °C, the reaction yield was 95 % or higher after 45 minutes. The reaction at 120 °C gave a yield o f 90 % or higher in approximately 90 minutes o f reaction time. The reaction at 120 °C proceeded at a moderate rate and takes significantly lesser time than the reaction at 80 °C. Also, there is lesser risk of damage to the catalyst or lower quality of product due to excessive heating o f the reactants. It is evident from the graphs in Figure 2.11 and 2.12 that the reaction achieved a stable FAME conversion after different periods o f time relative to the process temperature. These plateaus indicate that the reaction has gone to the full extent and all the TAG has been utilized in the production o f FAME. Governed by the conditions o f the reaction, these are achieved fastest for the highest temperature in Figure 2.12, while the reaction at 80 °C did not go to completion as may be seen from Figure 2.10. The reaction at 80 °C is not feasible over extended periods o f time, as the heating and constant stirring of the process medium consumes energy, which renders the process inefficient. 49 25 i 20 - 15 - Li. ♦ 100 ♦ 300 200 400 500 Time (minutes) Figure 2.10 The conversion o f oil to methyl ester using calcined ash as catalyst. The reaction conditions were 5 (wt %) catalyst, 80° C and a 12:1 molar ratio o f methanol to oil. The higher yields (-20 %). were obtained after 300 minutes o f reaction at 80°C. The ramp up time fo r the reaction was 25 minutes 50 100 90 c o e 0 > c o LLi 80 70 60 50 40 30 20 10 0 0 25 50 75 100 125 150 175 200 225 250 275 300 Time (minutes) Figure 2.11 The conversion o f oil to methyl ester using PBA catalyst. The reaction conditions were 5 (wt%) catalyst, 120° C and a 12:1 molar ratio o f methanol to oil. The highest yields (~90 %). were obtained after 95 minutes o f reaction. The ramp up time fo r the reaction was 25 minutes. 51 100 _ 80 S 70 > 60 8 50 LU 40 < LL 0 20 40 60 80 100 120 140 160 Time (minutes) Figure 2.12 The conversion o f oil to methyl ester using PBA catalyst. The reaction conditions were 5 (wt%) catalyst, 160° C and a 12:1 molar ratio o f methanol to oil. The highest yields (~95 %) were obtained after 45 minutes o f reaction. The ramp up time fo r the reaction was 25 minutes. 52 2.3.3 Catalyst Reuse To investigate the re-use capability of the catalyst the separated catalyst was washed with methanol and dried at 105 °C for 2 hours. This was then heated to 500 °C at heating rate o f 10 °C/min and maintained at 500 °C for 4 hours to bum all organic content that might be present from residual reactants. This catalyst was then used at the reaction conditions of 120 °C, 5 (wt %) catalyst and 12:1 Methanol to oil molar ratio. The catalyst showed some decrease in activity. Under similar reaction conditions, it gave a decreased FAME yield, and took longer to achieve the higher yields. The reaction yield curve for the re-use is shown in Figure 2.13. 53 80 — 60 ■2 50 0 g 40 o o LU 30 2 2; 20 0 50 100 150 200 250 300 350 400 Time (min) Figure 2.13 The conversion o f oil to methyl ester using recycled PBA catalyst. The reaction conditions were 5 (wt%) recycled catalyst, 12(f C and a 12:1 molar ratio o f methanol to oil. The highest yields (~75 %) were obtained after 160 minutes o f reaction. The ramp up time fo r the reaction was 25 minutes. 54 2.4 Summary and Conclusions Recent developments in harnessing biomass based energy in developed countries have led to the increase in production o f ash as residual waste. For highly efficient processes such as pellet burners, the bottom ash produced is rich in inorganic compounds such as metal carbonates and oxides. These inorganics existing in different states in the ash may be applied to a variety of uses such as forest fertilizers, land applications, soil amendments and other known techniques. The production o f ash is predicted to increase as the energy demands from renewable and sustainable sources grows and biomass is used to produce clean efficient energy. Wood pellets form a significant fuel source for small scale power facilities that utilize efficient combustion technologies and wood pellets prepared from waste wood to generate energy with lower particulate and carbon emissions. Harnessing biomass to create bioenergy is a fundamentally accepted technique to utilize waste generated by logging, pulp mill and other wood based operations. In recent years, efficient combustion techniques and waste treatment methods have led to the use o f waste wood to manufacture wood pellets that are used in pellet burners, gasifiers and boilers. The resulting final product, ash is rich in inorganic content as seen from the ICP-MS and XRD analysis. The presence of inorganic carbonates was observed by characteristic powder diffraction patterns o f Calcite, Fairchildite and Periclase (MgO) commonly associated with ash from woody biomass. Sieving the ash to particle sizes less than 150 pm improved the relative concentrations o f inorganic content and also gave finer particles for use as a heterogeneous catalyst. After calcination, the solid analysis by XRD was done to identify the useful metal oxides and justify the 55 application o f the ash as a heterogeneous catalyst. The work presents a reliable method and sufficient proof of a process to re-use the bottom ash from wood combustion in a pellet burner facility as a potential heterogeneous catalyst for the synthesis o f FAME from waste cooking oil. The highest yield o f 95 % was obtained for 160 °C, 12:1 methanol to oil molar ratio, 5 wt% catalyst and 155 minutes o f reaction by using this ash as a heterogeneous catalyst in the reaction. The ash and waste cooking oil have associated disposal and handling costs and pose significant issues to the operations that produce them. Waste cooking oil has been considered as a better alternative to refined vegetable oil in the production of biodiesel owing to its lower cost and reduced carbon emissions. To increasingly reduce our impact on the environment, the exploration o f unique applications and alternate utilization o f these waste streams is vital. The concept of utilizing two low value by-products to produce upgraded and useful products is a step in the right direction. The treatment of a readily available biomass waste and using it in a heterogeneous catalyzed process for manufacture o f Fatty acid methyl esters from waste cooking oil was demonstrated. 56 CHAPTER 3: Biomass gasification residue as a heterogeneous catalyst for biodiesel production 3.1 Introduction In recent years, vegetable oil based biofuels such as straight vegetable oil and biodiesel have emerged as renewable, carbon neutral alternatives and supplements to petroleum fuels (Gerpen et al. 2004; Mondal, Basu, and Balasubramanian 2008). Biodiesel is a mixture of mono alkyl esters resulting from the transesterification reaction between an alcohol and vegetable oil in the presence of a catalyst (Gerpen 2005). These esters are usually prepared by the reaction of methanol with the vegetable oil, resulting in production o f fatty acid methyl esters (FAME). Biodiesel is considered as an alternative fuel due to a significant decrease in greenhouse gas emissions, particulate emissions, total hydrocarbon emissions, sulphur content, and volatile organic content as compared to petroleum diesel (Hill et al. 2006). Fatty acid methyl esters produced from waste cooking oil by heterogeneous catalysts have been found to be cost competitive with conventional methods o f biodiesel production. These relatively low costs are due to a cheaper feedstock as well as less energy intensive neutralization and cleaning of the finished product (Demirbas 2007). Waste feedstock has been found to reduce environmental impact, waste disposal costs and production costs of biodiesel ( Lee and Foglia 2000; Canakci and Van Gerpen 2001; 57 Amaud et al. 2006; Phan and Phan 2008; Meng, Chen, and Wang 2008; Oner and Altun 2009; Borges et al. 2011). Heterogeneous catalysts have been used in a wide number of studies, to further decrease product cleaning costs and steps to neutralize homogeneous catalyst at the end o f the process (Borges et al. 2011; Kim et al. 2011; Arancon et al. 2011; Olutoye and Hameed 2013; Balakrishnan, Olutoye, and Hameed 2013). Gasification of biomass is a simple process to convert solid material to a gaseous fuel (Bridgwater 1995). It produces a fuel gas suitable for co-firing in existing boilers, or feeding gas engines and turbines to generate electricity (Femandez-Pereira et al. 2011). Focus on utilizing biomass based ash from gasifier operations is limited to a few studies, which have explored the potential use o f ash as an additive to building materials (Holt and Raivio 2005; Holt and Raivio 2006). Gasification occurs at a temperature o f about 750 - 900 °C in a reducing environment; the product gases are cleaned and the purified gas is burned together with coal, oil or natural gas (Moilanen et al. 1996). Small scale gasifier power plants have recently become commercially available to produce electricity with locally available biomass resources (Eberhardt and Pan 2013). Gasifier based energy generating operations produce solid by-products that are concentrated in inorganic constituents and unbumed carbon (Gomez-Barea et al. 2009; Femandez-Pereira et al. 2011). To improve process efficiency and application, re-use of gasifier ash is recommended. Furthermore, it is important that the process conditions be optimized to achieve maximum carbon conversion. The increase in the use biomass consumption for energy has led to an increase in ash production (Loo and Koppejan 2008). Current methods o f ash disposal and utilization 58 include landfilling, soil amendment, fertilizer for agricultural and forest land (Loo and Koppejan 2008; Vassilev et al. 2013b). Due to the presence of heavy metals, land application has associated risks with possible leachate of contaminants such as heavy metals (Izquierdo et al. 2008). Alternate applications such as using ash in construction material (Rajamma et al. 2009; G. Wang, Shen, and Sheng 2012), and as an adsorbent for pollutants (Umamaheswaran and Batra 2008; Mansha et al. 2011; Cheah and Ramli 2011) have also gained interest. The alternate application o f ash in the field o f heterogeneous catalysis is yet to be explored. As discussed earlier, the presence o f a catalyst in biodiesel production via transesterification offers improved efficiency in production and yield. The measurement of FAME yield is done by tools such as gas chromatography, infrared spectroscopy, 'H-NMR, gel permeation techniques among others. In this study, the real time yield of the transesterification reaction for FAME production was monitored by 'H-NMR. Previously, high-resolution 'H NMR has been used to monitor reaction progress for transesterification o f biodiesel among other parameters like degree o f unsaturation, and reaction intermediates (Gelbard et al. 1995; Gerhard Knothe 2000; Suppes et al. 2001; Neto et al. 2004; Morgenstem et al. 2006; Ghesti et al. 2007; F. Jin et al. 2007; Cabe^a et al. 2011; Anderson and Franz 2012). 'H-NMR is a fast and reliable tool that can be easily adapted for routine non-destructive analysis o f samples (Knothe 2001). Previous studies have monitored the yields by comparing the methoxy signal at 3.7 ppm (Cabe?a et al. 2011), the a-carbonyl methylene signal at 2.3 ppm (Morgenstem et al. 2006) and the glyceride signal ranging from 4.04 to 4.25 ppm (Ghesti et al. 2007). As the reaction progresses, the relative intensity of the methoxy signal 59 increases and therefore can be compared with the a-carbonyl methylene signal or the glyceride signal to confirm the conversion o f FFA to biodiesel. To determine the extent of conversion, various studies have suggested relationships based on integration of different peaks (Gelbard et al. 1995; Knothe 2000; Morgenstem et al. 2006; Cabe?a et al. 2011). In these studies different formulae have been developed and reviewed. The formulae listed below show the percent conversion by using different regions for integrations. Though the integrations are o f different regions in different formulae, the signal assignments are consistent throughout and detailed descriptions of each assignment may be found in the original articles (Gelbard et al. 1995; Knothe 2000; Morgenstem et al. 2006; Cabe9 a et al. 2011; Anderson and Franz 2012). These assignments and some details have been described previously in Chapter 2.2.1. The various equations from these studies are listed below. For all studies, the integration of methyl ester is approximately at 3.70 ppm. cw Morgensten = ^—j H ,ue .— QT ME C . . ------- = A nderson — *• ^ xioo OIL -------x l O O ■ Q r In this study, the bottom ash from a gasifier was used as a heterogeneous catalyst in the production o f FAME from waste cooking oil. The ash and the catalyst were characterized using ICP-MS, XRD, FT-IR, BET Surface area, TGA and SEM. Based on the results of XRD, ICP-MS and FT-IR the main elements and their phases were identified. The catalyst was developed and used in a batch reactor to produce FAME from waste cooking oil. The trans-esterification reaction progress was monitored by 'H-NMR. 61 3.2 Experimental 3.2.1 M aterials and methods Waste cooking oil was collected from both domestic and commercial cooking operations and the determined acid value o f oil was 3.32 mg KOH/g of sample. The cooking oil was filtered using a Whatman (number 4) filter paper, and mixed prior to use so as to ensure homogeneity o f the sample. The gasifier bottom ash (GA) used to prepare the catalyst was obtained from a gasification system located on campus at the University o f Northern British Columbia, Prince George, Canada. The biomass gasification system uses wood residues from a local sawmill to produce energy and has been operational since January 2011. The gasifier has a diameter of 4.3 meters and the accompanying flue gas boiler has a capacity o f 4.4 MW. The bioenergy plant based on biomass gasification has an annual energy output of 61,000 GJ, and is used for campus heating. For the solid characterization and analysis, inductively coupled plasma with mass spectrometry (ICP-MS) analysis on the ash was conducted using an Agilent Series 7500 ICP-MS machine. All samples were digested in concentrated nitric acid before analysis. The BET surface area determined by nitrogen adsorption was done on a Micromeritics HS112300 machine. The atmosphere was 70 % Nitrogen and 30 % Helium at 77 K. The thermo gravimetric analysis (TGA) was done on a TG50 instrument with 10 mg of sample. The heating rate was set at 10 °C/min, using Nitrogen gas at a flow rate of 20 mL/min. The maximum temperature was 900 °C, and the sample was held at this 62 temperature for 5 minutes. The X-ray diffraction (XRD) analysis to determine the mineralogy of the ash was done on a Bruker D8 Advance Series II machine. The radiation used was Cu- K al with wavelength of 1.5406 A, and 2® was varied from 10° to 90°. The scanning electron micrographs (SEM) were obtained on a Philips XL30 series microscope operated at an accelerating voltage o f 20 kV. Methanol (>95%), for use in the reaction was acquired from Fisher Scientific. The FT-IR spectra o f the ash and catalyst were obtained on a Perkin Elmer 2000 system using KBr to prepare the pellets. A total o f 8 scans were taken between the wavenumbers 400 cm '1 to 7800 c m 1. 3.2.2‘H-NMR Method The samples were analysed using ’H-NMR spectroscopy to determine the yield of the reaction. The ’H-NMR was taken using Fourier 300 equipment from Bruker, USA. The solvent used for ’H-NMR was chloroform-d (>98.9%) with 0.03% (v/v) tetramethylsilane (TMS) as an internal standard. The number of scans for each sample was set to 32. The two peaks used to evaluate the yield were the methyl ester peak, from 3.63 - 3.69 ppm and the oil signal from 4.25 - 4.35 ppm [37, 38]. To prepare the sample, 10 pL of each sample was dissolved in 0.8 mL of solvent in an NMR tube immediately before analysis. 3.2.3 Catalyst Preparation The gasifier ash catalyst was prepared in a two step process. The ash was sieved to obtain particle sizes <150pm which were then dried at 105 °C for 3 hours, followed by calcination in a muffle furnace. The temperature was increased from 500 °C - 800 °C at a 63 heating rate of 10 °C/min. The material was then kept at 800 °C for four hours before being cooled to room temperature. The final catalyst was stored in a dessicator until further use. 3.2.4 Experimental Procedure All the reactions were carried out in a batch reactor from Autoclave Engineers, USA. The EZE Seal reactor had a volume of 300 mL and was equipped with a liquid sampling outlet. The reactor was charged with 100 mL o f waste vegetable oil, 12:1 molar ratio of methanol to oil and the catalyst loading of 5 % by weight o f oil. The heating element was controlled by a PID controller and the ramp up time o f each reaction temperature was set to 25 minutes. Nitrogen was used to pressurize the reactor to reduce the formation o f a gaseous phase by methanol. The initial application o f heat was considered as time t=0 and samples were collected over various elapsed times. The liquid samples were analysed using 'H-NMR procedure described earlier. 64 3.3 Results and Discussion 3.3.1 Catalyst Characterization A summary o f the ICP-MS results is shown in Table 3.1. This includes the gasifier bottom ash (GA), sieved ash fraction and the catalyst. The ash is rich in calcium, potassium, magnesium and manganese. All these metals are residual plant nutrient metals left after biomass gasification. The high concentration o f the metals justifies the application o f gasifier bottom ash to processes that are catalyzed by basic catalysts. The particle size has an effect on the chemical and physical properties displayed by the ash. Table 3.1 also represents the chemical composition of sieved ash. As can be seen in Table 3.1, there was a significant improvement in the inorganic content of GA after sieving as determined by ICP-MS. The Calcium content was increased by 33 % and Magnesium by 27 % on segregating the GA to <150 pm particle size. The inorganic content is vital as it provides the possibility of catalytic properties. The BET surface area o f the GA catalyst was 7.1 m2/g. The major mass loss observed in the sieved bottom ash is initiated at approximately 650 °C, losing about 25 % o f the sample mass by 700 °C (Figure 3.1). Mass losses in this range are associated with release of carbon dioxide from metal carbonates such as calcium carbonate (Femandez-Pereira et al. 2011). The increase in inorganic content of the catalyst noted in the ICP-MS may be explained by this mass loss. 65 Table 3.1: Elemental concentrations in GA, GA <150/um, and GA catalystfrom the wood waste gasifier fo r important elements in decreasing order o f concentration as determined by ICP-MS. Gasifier Bottom Ash (As received) (mg/kg) Element Gasifier Ash (<150 jim) Relative increase after sieving Gasifier ash catalyst Concentration (mg/kg) (%) (mg/kg) Calcium 124946 167030 33.7 224021 Potassium 20077 18430 •8.2 17496 Magnesium 12308 15733 27.8 22993 Manganese 14852 15936 7.3 11844 Aluminium 6522 8463 29.8 20026 Iron 12339 12814 3.8 15574 66 100 -1 90 - c/a GA Catalyst c/a JO - - Gasifier Ash (GA) c/a c/a i 7° - 60 - 50 0 100 200 300 400 500 600 700 800 900 1000 Temperature (C) Figure 3.1. TGA curves o f catalyst and ash at heating rate o f l ( f C / min. 67 Figure 3.2 :SEM image at 2500x magnification o f gasifier ash as received after sieving to particle size < 150pm. The acceleration voltage was 20 kV. 68 Figure 3.3: SE M image at 2500x magnification o f calcined ash used as catalyst. The accelerating voltage was 20kV. 69 S (C) - Gehlenrte magne&ian, *yn - C*2 - PeticU se - MyO 12000 — S C ) - Fiuorapadte, syn - C a5 (P 0 4 )5 F f*l (*) Quartz, syn S i0 2 (•] (C ) - C e h le m te m a gn e a ta n, *y n - C a 2 *M g 0 .2 5 A K ).7 5 )(S 1.2 5 A I0 7 5 O 7 ) ffi <*) - P o ta ssiu m A lu m in u m S ik c a ta U n n a m e d z e o lite - K A lS i2 0 t> (¥1 > G O 40 U § < — *— GA Catalyst - -❖- - PBA Catalyst 30 to 20 10 0 100 150 200 250 300 350 400 Time (minutes) Figure 4.3: Conversion o f oil to methyl ester using recycled PBA and GA catalysts. The reaction conditions fo r both reactions were 5 (wt %) recycled catalyst, 120° C and a 12:1 molar ratio o f methanol to oil. The ramp up time fo r the reaction was 25 minutes. 96 The GA catalyst gave higher yields at both 120 °C and 80 °C as may be seen from Figures 4.1 and 4.2. The PBA catalyst was ineffective at 80 °C and only gave -20% yield after 450 minutes o f reaction (Figure 4.2). The GA catalyst on the other hand performed quite well at this temperature and resulted in -90% yield after 175 minutes o f reaction. The GA catalyst has approximately 22.4 wt% o f calcium and the PBA had 28.8 wt% from Table 3.1 and 2.1 respectively. Although these concentrations o f Calcium determined by ICPMS were comparable, but GA catalyst contained 70.9% CaO (Lime) while PBA catalyst only had about 45% as found by semi-quantitative XRD. This meant that the GA was lower in Calcium in the ash, but its preparation gave a higher CaO (lime) content in the catalyst. Apart from having a higher content o f the basic oxide, the GA catalyst also had a higher BET surface area than the PBA catalyst. Hence, high content of active metal oxide and large adsorption area for catalytic action are most probably the primary reasons why the GA catalyst performed better than PBA catalyst. The recycle o f the two catalysts was done in a similar procedure to evaluate the reuse capability. The PBA catalyst gave a better yield upon reuse than the GA catalyst as may be seen from Figure 4.3. The reaction condition o f the initial catalysts were the same, at 120 °C, 5 wt% catalyst loading and 12:1 molar ratio of methanol to oil. After the reaction, these catalysts were washed with methanol, dried and heated to 500 °C to bum organic content. Their reuse performance was tested by using them in the abovementioned reaction conditions again. The GA catalyst gave only -60% yield in the reaction while the PBA catalyst fared marginally better and gave -75% yield in 300 minutes o f reaction. The reduced action o f the catalyst may be attributed to deactivation due to reduced 97 surface area and residual organics, loss o f active sites due to heating and leaching. The presence o f higher CaO content which is affected by deactivation may decrease the yield of the catalyst significantly. Other compounds in PBA catalyst such as periclase (MgO) (Kouzu et al. 2008) also provide catalytic activity similar to that of lime (CaO) for the transesterification reaction. The lack o f these oxides in the GA catalyst may also contribute to a decreased yield in case of partial deactivation or leaching o f CaO content. The other identified phases in the GA catalyst such as minor quantities of phosphates and silica-aluminates are not active catalysts for the transesterification reaction. A comparison o f the properties o f two different biomass ashes and an insight into the methods that generated the residue is vital to understanding the applications of biomass ashes to transesterification. The ash must be o f high calcium content with preferably a large amount of oxides. In case the carbonates are the dominant phase, they must be calcinated to prepare oxides for good yield. Sieving the ash particles to finer sizes also increases the useful metal concentration by a significant amount. Ash from a pellet burner had lower surface area and lesser activity in the reaction. The gasifier ash or ash from oxygen deficient thermochemical degradation o f biomass has a very large surface area and significant inorganic concentration. The GA catalyst prepared with higher CaO content, has an excellent yield in the first run, but loses activity in subsequent runs probably due to leaching and deactivation. The PBA catalyst has a smaller surface area and the extent of deactivation is lesser which is observed by the better performance o f the catalyst upon re-use. Ash from complete combustion had better recycle properties, and ash from gasification had an excellent initial yield. 98 CHAPTER 5: Conclusions and recommendations for future work In this study, waste products generated in the vicinity o f University o f Northern British Columbia, Canada were used to prepare valuable products. A process for the manufacture o f biodiesel from waste cooking oil, using ash residue from bioenergy operations as a catalyst was demonstrated. In separate operations, two prepared catalysts were tested for the conversion of waste cooking oil to fatty acid methyl esters over a range of different temperatures. The two catalysts gave an excellent yield o f -95% over varying time periods. The gasifier ash (GA) catalyst performed better than pellet burner ash (PBA) catalyst. The current study employed and investigated a batch process for upgrading these wastes into useful products. For further research, the performance and product properties upon using a flow reactor and the ash catalyst on a fixed bed should be explored. The two catalysts were characterized by a variety of techniques, and major variations were seen in BET surface area, calcium metal concentration and amount o f CaO in catalyst samples. These differences were the prime factors that appeared to have governed the observable performance variations of each catalyst. The GA catalyst had higher calcium, CaO content and surface area. It gave higher yield in the first run, but lost its catalytic activity probably due to deactivation and leaching. The PBA catalyst had a lesser surface area and marginally lower calcium content. Besides CaO, it also had MgO present accounting for about 25% of the sample. It fared better than the GA catalyst in the recycle run. This is probably because there was lower leaching or deactivation in the PBA 99 catalyst due to a smaller surface area. For more clarity, the leaching properties o f species from both catalysts in methanol, and other organic solvents should be studied. Both wastes used in the process are o f environmental significance, with a long list o f applications that continue to grow. Recent years have seen waste cooking oil to be the source of a large number o f chemical products, including but not limited to biofuel and biolubricants. Ash from bioenergy processes has been validated as a soil amendment, forest fertilizer and additive in construction materials. The ash is a cheap residue that exists in large quantities in communities that utilize biomass for energy. The present day heterogeneous catalysts need to be prepared from abundant materials that are cheap and renewable. A study into the economics o f catalyst preparation and value o f products is also of relevance. The catalysts prepared from ash residue enhance the list o f alternate applications that biomass ashes may be employed for. The presence o f a plethora o f chemically active compounds such as carbonates, oxides, zeolites, quartz, aluminosilicates is a boost to the process significance of ash. It is imperative to develop new processes that provide competitive efficiency, reduced environmental cost and greater value. The process design and development may only be successful if we actively pursue unconventional sources o f chemical and mineral compounds and test their utility against current processes. It is certain that the large number o f inorganic phases in the ash will have an ever increasing range of applications. A temporal study into the cost-benefit facets of utilizing these alternate materials on a large scale would also be highly advantageous. 100 REFERENCES Al-Hamamre, Z., Foerster, S., Hartmann, F., Kroger, M., Kaltschmitt, M., 2012. Oil extracted from spent coffee grounds as a renewable source for fatty acid methyl ester manufacturing. Fuel 96, 70-76. Alptekin, E., Canakci, M., 2011. 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The ’HNMR analysis o f the control reactions (GAC-120) has also been included. The other reaction conditions were 12:1 molar ratio o f methanol to oil and 5 wt% catalyst. Density o f waste cooking oil Density o f waste cooking oil was measured by 5 repetitions. The density used was the average. (0.912 + 0.908 + 0.915 + 0.912 + 0.913)/ 5 = 0.91165, ~ 0.912 gm/mL Amount o f catalyst added Catalyst added was 5% by weight of WCO. In each reaction, 100 mL of WCO was used. Using density calculated above, mass of WCO used was 91.2 grams. The catalyst to be added was approximately 4.56 grams. In the GA-120 reaction, the amount o f catalyst added was 4.4629 grams. Amount o f methanol added The molar mass o f oil was taken as 856 gm/mol. Molar mass of methanol was 32.04 gm/mol. Based on mass of oil added, its corresponding moles were calculated. Then the 115 molar ratio o f 12:1 was used to determine moles o f methanol to be added. The moles o f methanol were translated to grams o f methanol by multiplication with 32.04. The weight o f methanol was converted to volume by using the density o f methanol at room temperature, 0.791 gm/mL. In the GA-120 experiment, 91.2 grams o f oil was used, representing (91.2/856) = 0.0107 moles of oil. The methanol to be added was (12*0.0107) = 1.279 moles o f methanol. The mass o f methanol to be added was (1.279*32.04) =40.96 grams The volume of methanol to be added was (40.96/ 0.791) = 51.78 mL. The methanol added in the reactor was 52 mL. Table B l: Table showing summary o f 'H-NMR values, and conversion calculations for gasifier ash catalyst (GA-120) and gasifier ash control (GAC-120) reactions. Conversion% 21ME GA-120 loiL (100 x Cme) 5 min 2 0 min 35 min 55 min 75 min 98 min 1 2 0 min 135 min 160 min 190 min 2 2 0 min 245 min 295 min 1.8903 0.888 0.0527 0.0163 0.0149 0.0168 0.0253 0.0189 0.0127 0.0132 0.0193 0.0163 0.0183 0.105 0.201 0.808 0.932 0.937 0.930 0.898 0.922 0.946 0.944 0.920 0.932 0.924 10.52 20.12 80.83 93.17 93.72 92.97 89.78 92.16 94.59 94.39 92.01 93.17 92.39 GAC-120 60 min 160 min 180 min 300 min 11.94 6.03 4.97 4.08 0.018 0.036 0.043 0.052 1.83 3.55 4.28 5.17 116 *a4auo-s i i *Ci\ftrttXflrVropBpuu.i\aa»ic3\Ti«-iioai—«i ptojoct\i\catt«icaMwi^ p a r o j« s t\Q a — l f i a r M fcV am ao 1 6S -(Z fcl20-7S « t ^ i------- + -• — o 2 4 Figure B5. ’H-NMR o f GA-120 at 75 mins 121 ZZl suiiu 8 6 1®On-VOJO --------f- I---- + - — 9 8 a jn S ij ------- b ~t .J____ > D C t A V i 3 * T 3 T M n e a \:ia > [u d T B « » T P ° T « - a c i.',r * i* o \T n n < I s * U .\i» 'O U B \'D . t T . I T " IC -D C im -S D . *a4U30-ui cs-aiao-iao ■!& 1 1 *CABn*mr\T>aygpln3>l\ourfcaNlllg-BioqiaBBl project atfi\GUao -8 _ i_ . e ----- r •1------- —+ ----- ■I------- 2 « Figure B7. ‘H-NMR o f GA-120 at 120 mins 123 «ae~CfcL20-135 fZZ) 1 1 'CiSMn*car\TOpgplfa. l\Curfca\nt8-l project\QM«ltAar ajaatSoaao C8-CHIZJ0-13S { | I | ..-I-------- .J-------- .-I— —r "1~.— 4_ _ . . --+J — c 2 4 Figure B 8.1H-NMR of GA-120 at 135 mins 124 0 (ppm] •OB-GJLL2G-1SD X X *C A » n * a r \T t> p B p ln 3 >I\Q n x 1 c a \m g - J lio a U i» a l p r o j t r t N O a —ttXax a A \O U 2 Q GS-QA12B-1S0 •I---- ”}— ------- j.. -I---- ---f— 2 4 Figure B9. 'H-NMR of GA-120 at 160 minutes 125 •00-43*120-1*0 1 x * c A B n ic a x \T p p g p ln 3 > l\Q m 3c3\T 1ig-M lo< n— • ! p r o j « c t \ a a — l C l a r a jf a V o u a o C 8 -G * U » -1 » 0 1------- -+----4-------- 6 2 * Figure BIO. 'H-NMR o f GA-120 at 190 minutes 126 0 [ppm] I *OB-GH120-22B C 8-G 2120 -2 2 0 1 ,CA»rrtcor\Tbpgpln3>lAQ«Uc3MHB-JloaUmal project \Qa—ld a r ittV C im 1 ulp, , ._ 4 ----------- ■I — ----- r s 4 2 Figure B ll. ’H-NMR o f GA-120 at 220 minutes 127 ■ a -a u o -a ts «u* c s - o u t - u s ajjB i a *c i \»n\>nlwr\Tqp^lai.l\OBHQMM-liodla»al projactVCMilClw ub\atQ20 et*oftcuo. n&4i ■1— ---------- E ftz;r :+r:;r 4 2 Figure B17. 'H-NMR o f GAC-120 at 300 minutes 133 0 [ppm]