Preparation and characterization of a novel efficient catalyst based on molybdenum oxide supported over graphene oxide for biodiesel synthesis

Abstract

In this study, a new catalyst for heterogeneous acid based on molybdenum oxide (MoO3) supported over graphene oxide (GO) was synthesized and applied in simultaneous esterification-transesterification reactions using waste cooking oil (WCO) to obtain biodiesel. In the catalyst synthesis, the GO support was synthesized from graphite oxidation, followed by wet MoO3 impregnation. The MoO3/GO catalyst was characterized by Surface Acidity, Thermogravimetric Analysis (TG/DTG), X-ray Diffraction (XRD), Fourier Transformation Infrared Spectroscopy (FTIR), Scanning Electron Microscope (SEM) and Energy Dispersion X-ray Spectroscopy (EDS). The application of the catalyst in the conversion of WCO into biodiesel had as parameters reaction temperature (120.0–160.0 °C), reaction time (1.0–5.0 h), catalyst loading of (2.0–10.0%) and methanol:oil molar ratio of (25:1–45:1). The results of the catalytic tests showed the best condition of biodiesel synthesis was 140.0 °C reaction temperature, 5.0 h of reaction time, 6.0% catalyst loading and 35:1 methanol:oil molar ratio, leading to a biodiesel with ester content of 95.6%. The catalyst showed good recovery and excellent catalytic performance in the reuse study, producing biodiesel with ester content above 70.0% after 5 reaction cycles. Thus, this study shows a promising new catalyst of heterogeneous acid with high catalytic activity and applicability in the biodiesel synthesis process.