97/04528 Catalyst deactivation studies in the dimethyl ether-to-hydrocarbons process: Sardesai, A. et al. Proc. Annu. Int. Pittsburgh. Coal Conf., 1996, 13, (1), 572–577

Abstract

The conversion of Dimethyl Ether (DME) to hydrocarbons is the latter step in the conversion of coal-derived syngas to hydrocarbons via DME. The shape-selective ZSM-5 zeolite catalysts play an instrumental part in this reaction in limiting the higher end of the product spectrum. This process being of an exothermic nature, the temperature rise across the catalyst bed causes some hydrocarbons to be deposited on the catalyst as coke. The presence of water as a by-product in the catalyst environment also enhances the catalyst deactivation. Deactivation of the ZSM-5 catalyst is studied in detail in terms of catalyst performance and life over a period of time. The conversion of DME and the hydrocarbon product distribution are studied as a function of time-on-stream. The SiO{sub 2}/Al{sub 2}O{sub 3} molar ratio of the ZSM-5 catalyst is regarded to be important in determining the degree of coke formation as well as the product distribution of the final hydrocarbon product. Catalysts used in aging experiments were studied as to determine the quantity and structure of the deposited coke. Extracted coke from the catalyst was analyzed via GC/MS methods.