Síntese direta do catalisador CeO2-SBA-15 dopado com MoO3 para aplicação na reação de transesterificação do óleo de soja.

Abstract

The steady increase in world consumption of fossil fuels has encouraged the development of new technologies for the production of fuel from renewable sources, taking into account the economic and energy needs of society. Among the alternative fuels are biodiesel which is a fuel which can be produced from vegetable oils or animal fats by the transesterification reaction with a short chain monoalcohol in the presence of a catalyst. Mesoporous materials, such as SBA-15, have been studied in the application of the transesterification reaction as catalytic support because it has a hexagonal structure with interconnected micropores, presenting a high surface area, thermal stability and uniform pore size. The addition of metal oxides, such as cerium dioxide and molybdenum trioxide in the structure of the SBA-15 molecular sieve, increases the activity and selectivity of the catalyst, improving its performance in the transesterification reaction. The present work aims to synthesize directly the SBA-15 with cerium dioxide in its structure for later doping with the molybdenum trioxide, to evaluate the crystalline and textural properties of these materials and their catalytic efficiency in the transesterification reaction. For this purpose, the cerium dioxide was inserted into the reaction mixture formed by the triblock copolymer Pluronic (P123), hydrochloric acid and the silica source, under agitation at 35 °C. The material obtained was dried and calcined under a flow of synthetic air at 550 °C for 6 hours. MoO3 was incorporated into the CeO2-SBA-15 material by the pore volume saturation method. From the diffractograms, the insertion of CeO2 into the structure of SBA-15 and the incorporation of MoO3 on the surface of the material, and from the adsorption/desorption isotherms of N2, the textural properties of the materials were verified. The methyl esters obtained during the transesterification reaction using the catalysts obtained were characterized according to Resolution Nº. 51 of 11/25/2015 of the National Agency of Petroleum, Natural Gas and Biofuels through the techniques of gas chromatography, density, viscosity and acidity index. The catalyst containing 15% by mass of molybdenum and the ratio Si/Ce = 10 reached the highest conversion to methyl ester with 87.2%.