Evaluation of Some New Zeolite-Supported Metal Catalysts for Synthesis Gas Conversion

Abstract

The use of bifunctional zeolite-based catalysts for the conversion of synthesis gas (carbon monoxide and hydrogen) to gasoline range hydrocarbons has recently attracted much attention. For example, the combination of metal oxides with the medium pore (about 6A) zeolite ZSM-5 and the use of a metal nitrate impregnated ZSM-5 catalyst have been shown to produce gasoline range hydrocarbons containing a high percentage of aromatics from synthesis gas. The production of gasoline range hydrocarbons which have a high olefin content has also been reported by using iron or cobalt impregnated ZSM-5 catalysts. The efficiency and selectivity of supported metal heterogeneous catalysts is closely related to the dispersion and particle size of the metal component and to the nature of the interaction between the metal and the support. For a particular metal, catalytic activity may be varied by changing the metal dispersion and the support, thus, the method of synthesis and any pre-treatment of the catalyst is important in the overall process of catalyst evaluation. Supported metal catalysts have traditionally been prepared by impregnation techniques that involve treatment of a support with an aqueous solution of a metal salt followed by calcination. In the Fe/ZSM-5, system, the decomposition of the iron nitratemore » during calcination usually produces iron oxides of relatively large crystallite size. This work was initiated in an attempt to produce highly dispersed, thermally stable supported metal catalysts which may be effective for synthesis gas conversion.« less