Estudo de catalisadores mesoporosos visando uso na reação de desidratação do glicerol

Abstract

The reaction of transesterification of oils and fats for biodiesel production generates glycerol as its main by-product, a low-cost and viable raw material for conversion into products with high added value. The glycerol dehydration reaction is an alternative to the partial oxidation of propylene (derived from fossil material) for the production of acrolein and acrylic acid, which makes the commercial development of the biodiesel value chain sustainable. Among the materials used, ZSM-5 zeolite in its acid form and SBA-15 mesoporous silica with natural sites are active catalysts for the glycerol dehydration reaction and selective for the production of acrolein. Thus, the objective of the present work was to synthesize the ZSM-5 zeolite with hierarchical pore structure through the alkaline treatment of desilication in the presence of a surfactant and the mesoporous silica Al-SBA-15 through the direct using different Si/Al to ratios use in the glycerol dehydration reaction. How they were characterized by different techniques to elucidate the influence on the reaction. A crystal structure of the ZSM-5 was confirmed by DRX and FTIR. By XRD and adsorption of N2, it was evidenced the obtainment of silica with highly regular mesopores, characteristic of SBA-15. For ZSM-5 zeolite, highlighted specific area and presence of micro and mesopores. The Al-SBA-15 Al-SBA-15 direct a direct relationship between the Si/Al ratio with a specific area and the volume of mesopores, indicating that the presence of aluminum affects the structure of the material. Through the chemical composition data, it was possible to establish a real Si/Al ratio and the theoretical acidity. ZSM-5 particles are spherical and crystals in plate shape and Al-SBA-15 in a cylindrical shape. The analysis of the physicochemical properties of the synthesized samples indicates that these materials are promising for a possible application in the glycerol dehydration reaction.