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Dimethyl ether, diethyl ether & ethylene from alcohols over tungstophosphoric acid based mesoporous catalysts

Ciftci, Aysegul
Tokay, Kenan Cem
Sezgi, Naime Aslı
Doğu, Timur
Tungstophosphoric acid (TPA) incorporated silicate structured new mesoporous catalysts were synthesized following one-pot hydrothermal and impregnation procedures. Surface area of TPA@MCM-41, which was prepared by impregnating TPA into MCM-41, was two orders of magnitude higher than the surface area of pure TPA and this catalyst showed very high activity in dehydration reactions of both ethanol and methanol. Ethanol fractional conversion values reaching to 1.0 was obtained at 300 degrees C at a space time of 0.27 s.g/cm(3), over TPA@MCM-41. Diethyl ether selectivity showed a decreasing trend by increasing temperature from 180 to 400 degrees C in ethanol dehydration reaction. Ethylene yield values approaching to 100% were obtained at temperatures over 250 degrees C. DME yield passed through a maximum at about 200 degrees C with this catalyst, over which coke formation caused catalyst deactivation. One-pot hydrothermal synthesis procedure was very successful to synthesize a catalyst (TRC-W40) which did not lose any activity after repeated washing steps. This catalyst gave highly stable catalytic performance in dehydration of both ethanol and methanol. Well dispersed WOx clusters were formed within the mesoporous silicate matrix of this material. This catalyst showed very good activity in dehydration reactions of alcohols, giving 100% conversion in ethanol dehydration at 400 degrees C and 100% DME selectivity in methanol dehydration at temperatures less than 300 degrees C.