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-Al 2O 3, possessing high surface areas, 400–460 m 2/g, and high porosity, 1.4–1.9 cm 3/g. The prepared alumina was characterized by powder XRD, SEM, and N 2 adsorption for BET surface area and porosity measurements. FTIR spectroscopy was employed to study the catalytic activity of meso-γ-Al 2O 3 and commercial γ-alumina, com-γ-Al 2O 3, in the dehydration reaction of methanol to dimethyl ether, DME. The prepared meso-γ-Al 2O 3 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, CO 2 and CH 4. However, as the flow rate decreased, more CO 2 formed and the DME selectivity decreased.