METHYLCYCLOPENTANE RING-OPENING AS A REACTION TEST FOR PT CATALYSTS SUPPORTED ON NONACIDIC MATERIALS

Platinum catalysts supported on non-acidic materials have been prepare d and characterized by electron microscopy (TEM), temperature programm ed reduction (TPR), hydrogen chemisorption, and methylcyclopentane rin g opening reaction. The analysis of the product distribution of this r eaction has been shown to be a powerful tool in the study of morpholog ical changes in the catalysts resulting from thermal treatments. Two c atalyst series, Pt/L zeolites and Pt/Mg(Al)O, have been investigated u sing this test reaction. By combining TPR and TEM measurements with th e analysis of the 3MP/2MP ratio in the products, it was shown that a h igh temperature calcination treatment on Pt/L zeolites resulted in a m igration of the Pt species out of the zeolite channels. Similarly the analysis of TPR experiments and the MCP-RO selectivity to n-hexane ove r Pt/Mg(Al)O indicated that, during the preparation of the catalysts, a large fraction of Pt species became trapped inside the bulk of the s upport and came out to the surface only after a cycle of oxidation/red uction at relatively high temperatures. (C) 1996 Academic Press, Inc.