Synthesis of solketalacetin as a green fuel additive via ketalization of monoacetin with acetone using silica benzyl sulfonic acid as catalyst

Abstract

Silica benzyl sulfonic acid (SBSA) was prepared as a catalyst for reacting monoacetin with acetone to synthesize solketalacetin as a green fuel additive. To synthesize SBSA, commercially available silica gel was functionalized with benzyl alcohol in the presence of sulfuric acid as catalyst and was then sulfonated with chlorosulfonic acid. The catalyst was characterized by FT-IR, XRD, and TGA. The catalytic activity of SBSA was compared with those of Amberlyst 36 and Purolite PD 206 as two sulfonated acidic catalysts, in a continuous flow system. The effect of different operation conditions such as acetone to monoacetin molar ratio, reaction temperature, and feed flow rate were investigated. Increasing acetone to monoacetin molar ratio increased the solketalacetin yield for the three catalysts but SBSA demonstrated the highest solketalacetin yield. Solketalacetin yield was reduced with temperature increase for all the catalysts and the maximum solketalacetin yields were recorded with Amberlyst 36 and SBSA catalyst at 20 °C and 40 °C, respectively. The catalytic activity was examined by keeping the catalysts on-stream for 25 h while the reusability tests were performed in four consecutive runs and showed that SBSA was stable up to 25 h and had the highest stability in 4 runs.