Síntese de óxidos metálicos e aplicação na desidratação catalitica do Glicerol

Abstract

The conversion of glycerol into products of higher economic value has become attractive due to the large production of this compound in the biodiesel industry, where it is generated as a byproduct. Many materials have been widely studied as potential catalysts for the conversion reactions of glycerol into products of higher added value. Among these catalysts, zeolites, mesoporous materials, and materials composed of mixed oxides involving transition metals stand out. In this sense, for this work we used mixed oxides synthesized by the Pechini method for application in the glycerol dehydration reaction. The FRX technique shows responses with lower values for aluminum percentages and higher for iron. The XRD analyses show characteristics of an amorphous solid, possibly due to small crystallite size. Although the RTP results have a smooth intensity profile, they corroborate with the values described in the diffractograms presented, indicating the different reduction ranges of the iron oxide. The Raman spectroscopy analyses confirm the presence of the aluminum and iron phases, from the specific stretching of these phases. Given the results of the SEM images it was possible to observe the sponge-like morphology, typical of the synthesis route used. The results of the catalytic tests showed high glycerol conversion, greater than 90%. The selectivity was higher for light products (acetaldehyde and acetic acid) with average values around 66%. Among all the species formed, the only product identified was acetol obtained through the dehydration of glycerol. The formation of acetol occurs mainly due to the role played by Lewis sites from iron and aluminum oxides in the dehydration process of glycerol.