The transesterification of soybean oil with methanol was carried out in the presence of Li-modified rice
husk ash catalyst at atmospheric pressure. The catalyst was prepared using a simple solid-state reaction,
mixing, and well grinding 1.00 g RHA with 1.23 g Li2CO3 calcined at 900 8C in air for 4 h. The catalysts
were characterized using XRD, SEM, FTIR, TGA-DTA, and the Hammett indicator. The XRD peaks were
mainly consistent with Li2SiO3. The catalyst was highly active because its basic strength (H_) exceeded
15.0. The catalyst was also air-insensitive, as only a few CO3
2 anions formed on the surface of catalyst
after exposure to air for 72 h, and no obvious LiOH formed on the catalyst surface. Under the optimal
reaction conditions of a methanol/oil molar ratio of 24:1, a 4% catalyst amount, and a reaction
temperature of 65 8C for 3 h, this approach achieved 99.5% conversion to biodiesel.