Biomass ash-based heterogeneous catalysts to produce fatty acid methyl esters from waste cooking oil.

Biodiesel is widely accepted for blending with conventional fuels such as diesel and gasoline. The development of cheap, durable heterogeneous catalysts for its production is a rapidly growing field of scientific investigation. Two heterogeneous catalysts were prepared from ashes of 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. ¹H-NMR was used to establish yield of 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. --Leaf ii.