Synthesis of core–shell Fe3O4@C@SiO2-SO3H/CH3 particles for the photothermally actuated esterification reaction in biofuel upgrade

Abstract

The synthesis of biodiesel is attracting tremendous attention both in academic and industrial fields in recent years. The use of acid heterogeneous catalyst for the production of biodiesel from low-cost raw materials with high free fatty acid is one of the research hotspots. This work reports the synthesis of Fe3O4@C@SiO2-SO3H/CH3 (SFCS) via layer-by-layer coating of carbonated polydopamine (PDA) and thiol-SiO2 on the Fe3O4 core, followed by the oxidation and acidification of thiol groups into sulfonic acid groups. TEM-EDX, BET, XRD, FTIR, and TGA were employed to characterize the structure and composition of SFCS. The esterification of oleic acid and methanol was photothermally actuated by near infrared light and the sulfonic acid groups on SFCS surface catalyzed the esterification with highest conversion of 93.2% of oleic acid. The SFCS can be recycled by magnet and reused.