Methanol dehydration to dimethyl ether over highly porous xerogel alumina catalyst: Flow rate effect

Template-free sol–gel synthesis in the absence of an acid catalyst resulted in mesoporous nanocrystalline γ-alumina, meso-γ-Al2O3, possessing high surface areas, 400–460 m2/g, and high porosity, 1.4–1.9 cm3/g. The prepared alumina was characterized by powder XRD, SEM, and N2 adsorption for BET surface area and porosity measurements. FTIR spectroscopy was employed to study the catalytic activity of meso-γ-Al2O3 and commercial γ-alumina, com-γ-Al2O3, in the dehydration reaction of methanol to dimethyl ether, DME. The prepared meso-γ-Al2O3 showed higher catalytic activity than the commercial catalyst with a conversion around 86% and DME selectivity around 99%. The products' selectivity showed a significant dependence on the flow rate of the feed gas stream. As the flow rate increased, the selectivity to DME increased on the account of the minor products, CO2 and CH4. However, as the flow rate decreased, more CO2 formed and the DME selectivity decreased.