Reactivity of Methane and Benzene over Metal/MFI Zeolite Analyzed with Temperature‐Programmed Reaction Technique

Abstract

Reactivity of methane and benzene over various metals supported on MFI zeolite was investigated in a wide range of temperature by a temperature-programmed reaction method. The oxidation state was also analyzed, as supported by X-ray absorption near edge structure (XANES). Pt, Rh, and Rh on MFI were reduced at < 600 K, and showed high activity for both benzene methylation and methane dehydrogenation, and hence, low selectivity for the methylation at high temperature.The short catalyst life of Pt/MFI suggests deactivation due to carbonaceous produced by the dehydrogenation. The oxidation state of Co species on ion exchange site of MFI was kept at + II in the experimental range (< 843 K), and relatively high selectivity was observed on Co/MFI even at high temperature.Stable oxidized state of Co species thus contributed to catalyze the target reaction (methylation of benzene with methane).

Direct methylation of benzene with methane over Co/MFI catalysts generated by self-dispersion of Co(OH)2

“…4 The reaction proceeded exclusively when MFI zeolite was employed as the support for Co among various structures of zeolites. 5…”

“…4 The reaction proceeded exclusively when MFI zeolite was employed as the support for Co among various structures of zeolites. 5 The conventional Co/MFI catalysts have primarily been prepared with an ion-exchange method. 6 The Co located at the α sites was active in the methane-benzene reaction 7 among three kinds of ion-exchange sites (α, β, γ).…”