Catalytic dehydration of methanol to dimethyl ether over nanosized WO3/Al2O3 system under inert and oxidative atmosphere

摘要

Samples of WO3 supported on gamma-Al2O3 with loadings w(WO3) = 1-30 % were prepared by impregnation method and subjected to heat treatment at 500 and 550 A degrees C for 3 h in a static air atmosphere. The catalysts were characterized by TG, DTA, XRD, TEM, TPD-pyridine, and N-2 sorption measurements. The surface acidity of the catalysts was investigated by the dehydration of isopropanol and the adsorption of pyridine and 2,6-dimethylpyridine. Catalytic activity and selectivity of the catalysts were investigated for the dehydration of methanol to dimethyl ether at 230 A degrees C in a conventional fixed bed flow type reactor at atmospheric pressure using nitrogen or air as a carrier gas. The results revealed that the catalysts with w(WO3) = 1-5 % loadings, calcined at 500 A degrees C, exhibit a considerable increase in the catalytic performance toward methanol dehydration. The increase was, however, much more pronounced with the catalyst containing w(WO3) = 5 %, which attained dimethyl ether in 89 % yield.