Methanolysis of Soybean Oil Using Tungsten-Containing Heterogeneous Catalysts

• Published in: Energy & fuels 2011-07, Vol.25 (7), p.2794-2802
• Main Authors: dos Santos, Vannia Cristina, Bail, Alesandro, Okada, Henrique de Oliveira, Ramos, Luiz Pereira, Ciuffi, Katia Jorge, Lima, Omar José, Nakagaki, Shirley
• Format: Article
• Language: English
• Subjects: Catalysis and Kinetics
• ISSN: 0887-0624; 1520-5029
• DOI: 10.1021/ef200055j

The development of alternative methods of biodiesel production still remains a major priority of the biofuel industry. In this work, the catalytic activity of anhydrous and insoluble sodium tungstate (Na2WO4) and its heterogenized form in silica (Na2WO4/SiO2) in soybean oil methanolysis was studied. The sol–gel process was conducted by both the acid and basic routes, and it was observed that the obtained solid catalysts Na2WO4/SiO2 presented different characteristics depending on the conditions employed during their synthesis. The solid catalysts afforded high methyl esters yields (above 95%) in one single reaction step, and they were amenable to recovery and recycling for at least four consecutive reaction cycles, during which high catalytic activity was maintained. Recovery and recycling were carried out by simple solid catalyst filtration and washing. In general, all the investigated silica-based solids were catalytically active for soybean oil transesterification; however, there was a decrease in the catalytic yield after each recycling process. The catalytic activity of the heterogenized silica solids was influenced by various physical parameters, such as specific surface area and textural properties. The structure of the solid catalysts and their catalytic behavior was also evaluated by X-ray fluorescence (XRF), X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and textural analyses.