Effect of ZrO2 on the catalytic performance of nano γ-Al2O3 in dehydration of methanol to dimethyl ether at relatively low temperature

A series of ZrO2/gamma-Al2O3 catalysts were prepared by incipient wetness impregnation of zirconyl nitrate hydrate aqueous solutions on nano-gamma-Al2O3 with ZrO2 loadings (1-30 % w/w) and calcined at 450 and 550 A degrees C for 3 h in a static air atmosphere. Physicochemical properties of the catalysts were determined using TG, DTA, XRD, FT-IR, Raman spectroscopy, TEM, and N-2 sorption measurements. The surface acidity of the catalysts was investigated by dehydration of isopropanol and adsorption of pyridine, 2,6-dimethyl pyridine and TPD-pyridine. This series of catalysts was used for vapor-phase dehydration of methanol to dimethyl ether in a fixed bed reactor. It was found that all catalysts in this study were active and selective for DME synthesis. According to the experimental results, 1 % ZA catalyst exhibited the highest activity with selectivity of 100 % toward DME.