HYDROGENOLYSIS AND ISOMERIZATION OF N-BUTANE ON LOW-INDEX PT SINGLE CRYSTALS AND POLYCRYSTALLINE PT FOIL

摘要

The hydrogenolysis and isomerization of n-butane over Pt(100) and Pt(111) single crystals and a polycrystalline Pt foil have been studied over a wide range of reaction temperatures (510-610 K) and hydrogen partial pressures (7.5-250 Torr), The activity and selectivity have both been determined as a function of temperature and hydrogen partial pressure, The more open Pt(100) surface was an order of magnitude more active than the close-packed Pt(111) surface, Hydrogenolysis selectivities were invariant with reaction temperature over the range studied, Hydrogen partial pressure affected both the activity and product distribution. Both single-crystal surfaces exhibit a decrease in the activity as the H-2 pressure is decreased below a critical amount and this decrease is directly attributable to the formation of a carbonaceous surface residue, The amount of isomerization was always less than the amount of hydrogenolysis regardless of the n-butane to hydrogen ratio or the reaction temperature. (C) 1996 Academic Press, Inc. [References: 30]