The catalytic properties of zeolite-supported metal catalysts

Y-zeolite, A-zeolite, and SAPO-5 supported-metal (Ru and Rh) catalysts were studied by XRD, NMR, AA, TEM, TPD, H{dollar}sb2{dollar} chemisorption and catalytic reactions.; The results of Ru/dealuminated Y-zeolite catalysts showed that the higher the dealumination the higher the metal dispersion. The activity and selectivity of CO hydrogenation were found to be correlated to the strength and concentration of the acidity. It is suggested that the activity on dealuminated Ru catalysts was enhanced through the secondary reactions as a result of increased acid site strength of the supports.; The metal particle size and location of a series of A zeolite-supported Ru catalysts have been investigated by ethane hydrogenolysis and cyclopropane hydrogenation as well as by H{dollar}sb2{dollar} chemisorption and TEM. Catalysts prepared by adding a Ru precursor to the synthesis gel had metal dispersed intrazeolitically. Catalysts prepared by ion exchange of Ru with A zeolite had metal particles primarily on the surface of the zeolite crystallites. All metal sites are accessible for ethane hydrogenolysis; however, molecular sieving strongly influenced cyclopropane hydrogenation.; SAPO-5 supported Rh catalyst were studied by CO hydrogenation. The activity showed an order of magnitude decrease with increasing reduction temperature while those RhHY and Rh/SiO{dollar}sb2{dollar} were essentially insensitive to reduction temperature in the range 300-500{dollar}spcirc{dollar}C. The H{dollar}sb2{dollar} chemisorption in RhSAPO-5 was also suppressed by a factor of 2 as the reduction temperature was raised to 500{dollar}spcirc{dollar}C. It is suggested that phosphorus, perhaps in the form of impurity amorphous AlPO{dollar}sb4{dollar}, in SAPO-5 played an important role in determining the CO hydrogenation activity of Rh.; H{dollar}sb2{dollar} TPD was carried out on a series of alkali cation exchanged Ru/Y catalysts. The TPD spectra indicated that the alkali cations in zeolite had no significant effect on the H{dollar}sb2{dollar} desorption of Ru in these catalysts.