The Conversion of Methanol into Higher Hydrocarbons Catalyzed by Gold

Abstract

AbstractGold/zinc oxide catalysts prepared by coprecipitation and containing gold particles of approximately 6 nm in diameter are active in the conversion of methanol to higher hydrocarbons under mild conditions. Conversions exceed 97 % under the selected experimental conditions at reaction temperatures of 350 °C, with a turnover number of 0.02 s−1. Both alkanes and alkenes up to C6 are formed, with a selectivity of approximately 44 %C hydrocarbons and 56 %C dimethyl ether. The addition of zeolite‐Y in composite catalysts modifies the product spectrum slightly. Ethene and propene dominate the alkenes formed above 450 °C if a 1:1 HY:Au/ZnO composite is used; the dominant alkane under these conditions is methane. At 475 °C only three hydrocarbons are present with selectivities of 13 (methane), 39 (ethene), and 48 % (propene). The carbon−carbon bond formation was not seen in earlier work when syngas (CO plus H2) was converted with the same Au/ZnO catalyst at high pressure to form mixtures of alcohols and hydrocarbons. This suggests that the formation of higher hydrocarbons from methanol is inhibited in the presence of CO and/or H2, probably due to competitive CO adsorption on the gold surface.