Metal-Zeolite Catalysts for the Conversion of Synthesis Gas to Selected Hydrocarbon Products

Abstract

It is well known that the medium-pore zeolite ZSM-5 can catalytically convert methanol or other oxygenates to hydrocarbons containing aromatics [1]. The conversion is normally carried out in the temperature range 300°–400°C. The acid function of ZSM-5 is responsible for the catalytic synthesis of aromatics. The shape-selective behavior stemming from the medium-pore size (diameter of 5.5 Å results in a sharp cut-off in the aromatic product distribution at C10. The reaction path [2–4] involves the following steps:(a) dehydration of methanol to dimethylether and subsequently to ethylene and propylene, (b) oligomerization of light olefins to heavier olefins, and (c) isomerization, cyclization, and aromatization. The liquid hydrocarbon product contains blanched paraffins, blanched olefins, naphthenes, and aromatics, and has a high octane rating.