Process to convert synthesis gas to olefins over a bifunctional chromium oxide/zinc oxide-sapo-34 catalyst

Abstract

A process for preparing C2 and C3 olefins comprises contacting a feedstream including hydrogen, carbon monoxide, and a bifunctional catalyst in a reaction under certain specified conditions. The catalyst includes as components (1) chromium oxide and zinc oxide mixed metal oxides, and (2) a SAPO-34 molecular sieve. The resulting product of the reaction is relatively high in the target lower olefins and relatively low in less desirable products, including C2 and C3 paraffins, C4+ hydrocarbons, oxygenates, and methane, thereby reducing or eliminating the need for certain previously common and costly separations. The bifunctional catalyst as used in the inventive process also offers improvements in catalyst life in comparison with some methanol-to-olefins catalysts. The process may be carried out as a single unit operation.