The Effect of Preparation Method on Pt/Nb2O5 Catalysts

• Autor(a) principal: Eleutério,A.
• Data de Publicação: 1998
• Outros Autores: Santos,J.F., Passos,F.B., Aranda,D.A.G., Schmal,M.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Brazilian Journal of Chemical Engineering
• Texto Completo: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66321998000200014
• topic: Preparation method; catalysts; n-heptane

The use of the ion-exchange method and the addition of lithium to Pt/Nb2O5 catalysts were investigated in this work, using techniques of temperature-programmed reduction, H2 and CO chemisorption, UV-Vis diffuse reflectance spectroscopy and the conversion of n-heptane as a catalytic test. The superficial precursor present after the calcination step is platinum oxide, as previously observed for Pt/Nb2O5 catalysts prepared by the incipient wetness method. For some of the samples, autoreduction was observed during the calcination step, with the formation of low dispersion metallic platinum. The Pt/Nb2O5 catalysts prepared by ion exchange showed a high yield of olefins, as compared to aromatics, in the conversion of n-heptane. However, a high yield of hydrogenolysis products was also observed. For some of the lithium-containing samples, there was a suppression of dehydrogenation and aromatization reactions, with an increase in central C-C bond hydrogenolysis.