Synthesis, optimization and characterization of biochar based catalyst from sawdust for simultaneous esterification and transesterification

Abstract The development of a benign environmental catalyst for the generation of biodiesel is an area of importance to reduce the overall usage of fossil fuels. In the current work, biochar was produced by slow pyrolysis of Irul wood sawdust. The optimization for biochar generation was carried out for different reaction temperatures and heating durations. The biochar was used to prepare solid acid catalysts by sulfonation process. The characterization of biochar and the sulfonated catalyst were carried out using Elemental analysis, Fourier Transform Infrared spectroscopy (FTIR), Powder X-ray Diffraction (XRD), Thermo Gravimetric Analysis (TGA), Scanning Electron Microscopy (SEM) and Surface area analyzer (BET). The characterization results showed that sulfonation of biochar resulted in biochar based solid acid catalyst containing various functional acidic groups like weak acidic OH groups, strong acidic COOH and SO 3 H groups. The total acid density and sulfonic acid group density of catalyst were estimated and showed excellent acidic sites concentration which gives a good catalytic activity for biodiesel production through simultaneous esterification and transesterification. The enhanced catalytic activity is due to the high acid density of SO 3 H groups and the reactant accessibility towards acidic sites as well as the strong affinity between the hydrophilic reactants and the neutral OH groups which are bonded with the polycyclic aromatic carbon rings. The performance of biochar catalyst for the production of biodiesel was evaluated by comparing the yield obtained. The FTIR and Gas Chromatography–Mass Spectroscopy (GC–MS) were also carried out for the analysis of biodiesel produced.