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 ₂O₃, possessing high surface areas, 400-460 m ²/g, and high porosity, 1.4-1.9cm³/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 CH ₄. However, as the flow rate decreased, more CO₂ formed and the DME selectivity decreased.