DEHYDRATION CATALYSTS FOR THE METHANOL DIMETHYL ETHER REACTION

Catalysts for the rnethanolidimethyl ether reaction are reviewed with particular emphasis on the arid/base properties of the catalysts. The focus is on temperatues less than around 30O°C and atmospheric pressure conditions, which correspond to potential automotive applications. Mechanisms including both dual site (acid/base) Langmiur-Hinshelwood and single site Rideal-Eley mechanisms have been postulated, with both Bronsted and Lewis acid sites involved in the dehydration reaction. Temperatures Temperatures.higher than about 300°C, as well as a strong surface acidity, tend to promote the further dehydration of DME to form cj-cj olefins and eventually hydrocarbon products in a series type reaction sequence. Methods exist, particularly in zeolites, to control the strength and type of surface acidity, and therefore the selectivity to DME. © 1991, Taylor & Francis Group, LLC. All rights reserved.