A Highly Active, Readily Synthesized and Easily Separated Graphene Oxide (GO)/Polyethersulfone (PES) Catalytic Membrane for Biodiesel Production

Heterogeneous acidic catalysts offer many advantages such as lower corrosion, easier separation and lower production cost compared with homogeneous sulfuric acid. Graphene oxide (GO) containing trace amount of oxygen-containing functional groups have been demonstrated to be effective carbon-based solid acid catalyst. However, GO are difficult to be recovered from liquid reaction system for further utilization. Graphene oxide/Polyethersulfone (PES) catalytic membranes were prepared and employed as heterogeneous acid catalysts in the esterification of oleic acid with methanol for biodiesel production. The membrane was annealed at different temperatures to promote the catalytic activity and reusability. As predicted, the OA conversion increased greatly with the increase of GO content in the membrane. Both internal and external diffusion have no influence on the catalytic activity. The catalytic membrane dosage, reaction temperature and methanol/oleic acid molar ratio affected its catalytic performance significantly. Among all the prepared membranes, the membrane annealed at 150 °C exhibited the best catalytic performance, with a conversion of over 85 % even after six cycles.