Solid Acid Catalyst Derived from Coffee Residue for Biodiesel Production

Abstract

Biodiesel is a free fatty acid methyl ester (FAME) produced from transesterification of oil and short-chain alcohol. Nowadays, the cost of conventional biodiesel production might not be competitive with petro-diesel due to the cost of refined oil as a main feedstock. Many challenging researches have proposed method or technology to efficiently produce biodiesel. One of the most important knowledge is the synthesis of the suitable catalyst for biodiesel production. Solid acid catalyst is a promising catalyst to produce biodiesel from low-cost feedstocks since it can catalyze simultaneously esterification of free fatty acid (FFA) and transesterification of triglyceride. To improve the biodiesel CO2 cycle, the waste material, coffee residue, was selected as a supported catalyst. It provides the appropriate textural properties such as high surface area with mesoporous structure and hydrophobic properties. The sulfonation with concentrated H2SO4 was used for additional acidic functional group which exhibits a strong protonic acid site density. Therefore, this research aims to synthesize sulfonated activated carbon derived from coffee residue (SCAC) to catalyze esterification of caprylic acid as a model of FFA. The sulfonation temperature varied from 140 to 200 °C as named SCAC-140, SCAC-160, SCAC-180, and SCAC-200 catalysts.