Conversão de glicerol sobre CeO2/CuO/ZrO2 com e sem o uso de um direcionador na síntese do suporte

Abstract

Results of the study of the effect of two routes on the synthesis of zirconium dioxide (ZrO2) for use as support in CuO and CeO2/CuO catalysts are presented. ZrO2 was prepared by the sol- gel method in the absence and presence of the chitosan biopolymer, aiming to increase its porosity and, consequently, the dispersion of copper and cerium oxides. CuO and CeO2 (7 and 10% by mass, respectively) were added via the wet impregnation method with aqueous solutions of copper and cerium nitrates. The samples were calcined at 500 °C and, subsequently characterized by H2 temperature programmed reduction (RTP-H2), temperature programmed desorption of pyridine (DTP-py), UV-vis spectroscopy of solid samples and thermogravimetric analysis (TG). The catalytic performance evaluation was carried out in the dehydration reaction of glycerol in the gaseous phase and atmospheric pressure. The prepared support is black, different from the commercial material, resulting in a low band gap, confirmed by spectroscopy. The results indicate superior dispersion of CuO in the support prepared in the presence of chitosan. Both supports have low acidity; however, using the biopolymer resulted in more acidic sites per mass. Although all samples showed a marked rate of catalytic deactivation, changes in material properties due to the use of the biopolymer resulted in superior glycerol conversion. The product with the highest selectivity was acetol (55%), slightly higher in the samples synthesized using chitosan.