Role of sulfuric acid modification to coconut shell activated carbon in waste cooking oil upgrading

The conversion of waste cooking oil to biofuel is appealing as it encompasses waste management and the introduction of an alternative clean source of energy. The biofuels market will prosper with the increasing demand for fuels, environmental laws and concerns, and energy security issues. This research aims to increase the hydrocarbon yield in catalytic cracking of waste cooking oil over acid-modified activated carbon. Sulfuric acid is used as an acid-modifying agent to increase the surface acidity of coconut-shell-activated carbon with varying acid concentrations. The modified catalysts have been characterized by BET, SEM-EDX, XRD, FTIR, TPD-NH3, and TGA. The performance of the acid-treated catalysts has been compared with that of pristine activated carbon and non-catalytic processes. It was found that increasing the acid concentration during preparation increased the liquid yields while lowering gas output. In the present study, using a 20% sulfonated AC catalyst gave the highest alkene fraction (36%) in the hydrocarbon yield. Hence, acid modification with sulfuric acid could be regarded as a low-cost and simple pre-treatment step for activated carbon in order to increase its acidity for better catalytic cracking performance.