Synthesis of nano-CaO catalyst with SiO2 matrix based on palm shell ash as catalyst support for one cycle developed in the palm biodiesel process

Abstract

In this research, waste chicken eggshells and palm oil mill boiler ash were utilized as heterogeneous solid base catalysts in biodiesel synthesis. The utilization of solid waste as a catalyst source can increase economic value and is an environmentally friendly process. This research aimed to investigate the effectiveness of catalyst for biodiesel synthesis using palm oil. Eggshell-nano-CaO was impregnated with various palm ash concentrations (10–50 wt%) and various calcination temperatures (600°C-900 °C), followed by drying and calcination. Biodiesel synthesis using palm oil was conducted at 60 °C, 15:1 methanol ratio, and 500 rpm. It was also conducted with various catalyst concentrations (2–5 wt%) and reaction times (60–180 min). The average particle size of eggshell-nano-CaO is 24.98 nm. At 800 °C, the calcination temperature has the highest surface area of 21.483 m2/g with an average pore size of 5.331 nm and a pore volume of 0.057 cc/g. In addition, catalyst has high basicity, which is 8 mmol/g. The maximum yield of 97% methyl ester content was obtained with 20 wt% palm ash concentration and 800 ᵒC calcination temperature. Heterogeneous catalysts derived from waste chicken eggshells and palm shell ash have high potential as solid-base catalysts in biodiesel synthesis.