Synthesis, characterization and use of alumina doped with TiO₂ and ZrO₂ to produce biofuels from soybean oil by thermal cracking, transesterification and hydroesterification

In this work, different metal oxides containing Ti, Zr and Al were prepared and characterized and their catalytic activities for cracking, transesterification, and hydroesterification reactions of soybean oil were evaluated. It is described the synthesis of the solids by co-precipitation, and their characterization by thermogravimetry, X-ray diffraction, Brunauer-Emmet-Teller surface area determination, Fourier-transformed Raman spectroscopy, and the determination of Lewis and Brønsted acid sites by pyridine adsorption and detection through Fourier transform infrared spectroscopy (FTIR). The hydrocarbons obtained by soybean pyrolysis were analyzed by fractional distillation, acid number, FTIR, density (at 20 °C), viscosity (at 40 °C), and calculation of the cetane number. The results suggest that all of the solids exhibit catalytic activity at the second stage of the cracking reaction (deoxygenation), lowering the final acidity of the products. The solids also exhibited catalytic activity for transesterification and hydroesterification of triacylglycerides, leading to good yields in methyl fatty acid esters. (author)