Fabrication of Heterogeneous H6PV3MoW8O40/AC-Ag Catalyst for Biodiesel Production from Low-Quality Oils

Abstract

Herein, we first modified commercial activated carbon (AC) with different metal ions (Cs+, K+ and Ag+), and then H6PV3MoW8O40 acids were incorporated into as-modified supports。The 35%H6PV3MoW8O40/AC-Ag hybrid catalyst showed highly catalytic performance for transesterification of soybean oil. The best oil conversion of 91.3% was achieved under optimized conditions: methanol/oil ratio of 30:1, reaction time of 10 h, reaction temperature of 140 °C and catalyst dosage of 8 wt.%. Characterization results of XRD, IR, ICP and TG indicated that H6PV3MoW8O40 was highly dispersed on the AC-Ag support as the loading was less than 35%. Proton exchange with Ag may contribute to the highly dispersion of H6PV3MoW8O40 on the support, thereof leading to the increased stability. The as-prepared 35%H6PV3MoW8O40/AC-Ag catalyst was recycled and had good resistance to free fatty acid (FFA) and water, which were included in low-quality oils. Moreover, the solid acid catalyst could simultaneously catalyze the transesterification of soybean oil and esterification of FFA, and a probable mechanism of the catalytic process was also proposed. All the features of this novel solid catalyst are more advantageous than homogenous H6PV3MoW8O40 catalyst, successfully creating an efficient and sustainable approach of biodiesel production especially from low-quality oils.