COMPARATIVE CATALYTIC STUDIES ON THE CONVERSION OF 1-BUTENE AND N-BUTANE TO ISOBUTENE OVER MCM-22 AND ITQ-2 ZEOLITES

Abstract

The catalytic properties of H-MCM-22 and Pt-MCM-22 for the skeletal isomerization of 1-butene and the dehydroisomerization of n-butane were compared with those obtained from their delaminated derivatives, H-ITQ-2 and Pt-ITQ-2. The overall results of our study strongly suggests that the desired 1-butene and n-butane conversions to isobutene in steady state occur mainly near the pore mouth inlets of the sinusoidal I 0-ring channels retained in both of MCM-22 and ITQ-2 and inside this intralayer void space, respectively, which may be attributed to the unique geometric constraints imposed by the two-dimensionality of the pore system with a suitable degree of ellipticity of 10-ring channels. Whereas coke for-mation on the sinusoidal channels during the 1-butene skeletal isomerization can occur in such a way as to make most of the intrachannel Bronsted acid sites less available for nonselective dimerization-cracking reactions, it appears that the presence of H2 in the n-butane dehydroisomerization stream would prevent extensive coke buildup, thereby allowing pore diffusion of reactants and products even in steady state. (c) 2006 Elsevier Inc. All rights reserved.