Optimised Biofuel Production via Catalytic Cracking of Residual Palm Oil Recovered from Spent Bleaching Earth (SBE) over Ni/HZSM-5 Zeolite

Abstract

The concerns over the depletion of fossil fuel and security of energy supply have directed an increasing awareness about biomass or waste-derived energy. Fresh bleaching earth (BE) is used to remove colour, phospholipids, oxidised products, metals, and residual gums in the palm oil process refinery. Once the adsorption process ends, the spent bleaching earth (SBE) which contains approximately 20-40 wt% of the adsorbed oil, is usually disposed to landfills without any treatment. Thus, SBE as one of the major biomasses or wastes available in Malaysia is a potential source for hydrocarbon fuel production. Therefore, this study reported the employment of heterogeneous catalyst cracking of residual palm oil in SBE into liquid products by 15%Ni/HZSM-5 catalyst and the optimisation of the process. The experiments were designed using central composite design (CCD) approach via response surface methodology (RSM) to study the relationships of catalytic cracking temperature (400-500°C), heating time (60-180 min), and nitrogen flow rate (60-100 mL/min) on the liquid products yield. The experimental results were thoroughly analysed using analysis of variance (ANOVA). The optimum liquid products yield of catalytic cracking of residual palm oil in SBE was 12.91 wt% achieved at 452°C, 160 min of heating time, and 86 mL/min of nitrogen flow rate. On the basis of the obtained results, the heterogeneous catalyst of 15%Ni/HZSM-5 could be a potential catalyst for the conversion of residual palm oil in SBE into liquid products.