Aromatization of dimethyl and diethyl ethers on Mo 2C-promoted ZSM-5 catalysts

Abstract

The adsorption and reaction pathways of dimethyl and diethyl ethers have been investigated on pure and Mo 2C-containing ZSM-5. The catalysts have been characterized by XPS and surface acidity measurements. FTIR spectroscopic measurements indicated that a fraction of both ethers dissociates on pure and Mo 2C-promoted zeolites already at 180–200 K resulting in the formation of methoxy from dimethyl ether, and ethoxy from diethyl ether. TPD experiments following the adsorption at 300 K showed desorption profiles corresponding to starting compounds and their decomposition products (methane, ethene and propene). ZSM-5 effectively catalyzed the reaction of dimethyl and diethyl ether above 473 K to yield various olefins and aromatics. From dimethyl ether xylene and from diethyl ether toluene were the main aromatic compounds. Adding Mo 2C to the zeolites greatly promoted the formation of aromatics very likely by catalyzing the aromatization of olefins formed in the reaction of ethers on zeolites.