Synthesis, characterization and application of H-MCM-22, Ga-MCM-22 and Zn-MCM-22 zeolite catalysts in the aromatization of n-butane

The H-MCM-22, Ga-MCM-22 and Zn-MCM-22 zeolite catalysts were synthesized and characterized by X-ray powder diffraction, scanning electron microscopy, X-ray fluorescence, energy dispersive X-ray analysis, temperature programmed desorption of ammonia and nitrogen adsorption. The study of the acidic properties of the synthesized zeolite catalysts revealed that the catalysts comprised of Bronsted and Lewis acid sites. n-Butane aromatization was investigated over the H-MCM-22, Ga-MCM-22 and Zn-MCM-22 zeolite catalysts. The effect of reaction temperature, weight hourly space velocity and time on stream on the conversion of n-butane and selectivity to aromatic hydrocarbons were studied over the synthesized catalysts. The type and nature of active sites in the aromatization of n-butane over the prepared MCM-22 catalysts have been examined. The reaction mechanism of n-butane conversion and the shape-selective property of the MCM-22 catalysts in light of their unique pore system with supercages are also discussed. The Ga- and Zn-modified MCM-22 zeolite catalysts exhibited high activity in the conversion of n-butane and selectivity to aromatic hydrocarbons. The aromatic hydrocarbons produced over these catalysts were benzene, toluene, ethyl benzene and isomers of xylene.