Aplicação das técnicas de redução a temperatura programada (RTP) e dessorção a temperatura programada de amônia (DTP – NH3) em catalisadores de níquel

Abstract

The present work consisted in applying the techniques of Temperature Programmed Reduction and Temperature Programmed Desorption of Ammonia in the characterization of Ni and/or Cu, in order to understand the methods and to verify their applications in catalysis. The catalysts were prepared by wet impregnation method and the submitted to the chosen methods. The RTP profiles of materials allowed the identification of maximum temperature reduction and the quantification of hydrogen consumption. It was observed that the particle size influences the profile support and the amount of hydrogen consumed during the analysis. With DTP-NH3 was possible to quantify the acidity and by the temperature range of desorption of ammonia obtain the strength of acidic sites in each catalyst. This analysis showed that for catalysts based on Ni and Cu supported on Nb2O5 the order of impregnation of the metals interferes in the acidity of these materials, but not in the strength of acidic sites. The results obtained from both techniques permit a better understanding of catalytic properties, allowing the best choice of the parameters used during the catalytic reaction (maximum temperature of activation, for example), as well as the actual composition and preparation methods of catalysts, favoring therefore a longer life of the catalysts used and a higher obtainment of hydrogen.