Oil palm trunk and sugarcane bagasse derived solid acid catalysts for rapid esterification of fatty acids and moisture-assisted transesterification of oils under pseudo-infinite methanol

•Biodiesel was produced using oil palm trunk and bagasse derived catalysts.•Pseudo-infinite methanol promoted facile access of reactants to Bronsted acid sites.•Rapid esterification of fatty acids under pseudo-infinite methanol.•Prolonged moisture-induced violent bumping increased rate of transesterification.•Two-folds FAME yields in the presence of 8.3% moisture compared to neat oil.

The use of pseudo-infinite methanol in increasing the rate of esterification and transesterification reactions was studied using oil palm trunk (OPT) and sugarcane bagasse (SCB) derived solid acid catalysts. The catalysts were prepared by incomplete carbonisation at 400 °C for 8 h, followed by sulfonation at 150 °C for 15 h and characterised using TGA/DTA, XRD, FT-IR, SEM–EDS, EA and titrimetric determinations of acid sites. Under optimal reaction conditions, the process demonstrated rapid esterification of palmitic acid, with FAME yields of 93% and 94% in 45 min for OPT and SCB catalysts, respectively. With the process, moisture levels up to 16.7% accelerated the conversion of low FFA oils by sulfonated carbon catalysts, through moisture-induced violent bumping. Moisture assisted transesterification of palm olein containing 1.78% FFA and 8.33% added water gave FAME yield of 90% in 10 h, which was two folds over neat oil.

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