Lawrence Berkeley National Laboratory

This study investigates the effect of zeolite nano-catalyst on the yield of biodiesel and biochar formed from the pyrolysis of tallow (cow fat). Residual waste cow fat was pyrolyzed in a fixed-bed reactor of laboratory-scale volume 2200 cm3, at operating temperatures of 450, 500, 530, and 580 °C and heating rates of 4, 5, and 6 °C/min. The molecular composition of cow fat was analyzed using a gas chromatography molecular spectrograph (GC-MS). It was observed that the biodiesel produced without a catalyst was mainly composed of aromatic carboxylic acids, esters, alkanes, alkenes, and alkanes, while the biodiesel produced with zeolite nano-catalyst consisted mainly of methyl esters, pentanoic acid, heptanoic acid, cyclo-olefins, 4,4-dimethylcyclohexene, butyl-cyclohexane, butyl-cyclopentane, and 1-pentylcyclopentene. A biodiesel yield of 58% was achieved when a 1% zeolite nano-catalyst was used to pyrolyze the tallow at an operating temperature of 530 °C and heating rate of 6 °C/min. When the tallow was pyrolyzed without a zeolitic catalyst, decarboxylation was promoted, and a higher biodiesel yield of 82.78 wt% was achieved. Results from this study revealed that although zeolite nano-catalyst did not show an incremental effect on the yield of biodiesel, it favors biogas production and biochar formation.