Synthesis and characterization of modified γ-Alumina-NaA and γ-Alumina-NaX zeolite composites as methanol dehydration catalysts in synthesis Dimethyl Ether (DME)

Abstract

Dimethyl ether (DME) is of great interest due to its wide application. It is currently being demonstrated for use as an alternative diesel fuel or substituting LPG for household. DME production via methanol dehydration reaction is affected by textural properties and catalyst surface acidity. The experimental study of textural properties in addition to surface acidity of both γ-Al2O3 prepared in this study and modified γ-Al2O3 over zeolite A and X mixing were conducted. The catalysts were characterized by N2 adsorption-desorption, X-Ray diffraction (XRD), and temperature programmed desorption of ammonia (NH3-TPD). Referring to N2 adsorption/desorption isotherm using the Brunauer-Emmerr-Teller (BET) equation, the catalysts were observed possessing high specific surface area (170-279 m2 g-1) and pore diameters of 5.6 - 8.8 nm (mesoporous). The XRD patterns of all catalysts still reveals clear peaks of γ-Al2O3 components. The strength of the acid sites of alumina modified with zeolite A is categorized as medium acid sites, whereas modified by zeolite X varies.