Catalytic performance of the dodecatungstophosphoric acid on different supports Original Research Article

Varying amounts of tungstophosphoric acid (HPW) have been supported on Y-type zeolite and silica using the incipient wetness method. The catalytic activity of the catalysts was studied in the vapor-phase dehydration of ethanol. The reaction was carried out in a conventional flow-type reactor under atmospheric pressure at temperatures changing from 398 to 773 K.Unexpectedly, deposition of heteropolyacid on zeolite HY with the loadings decreasing from 46.8 to 0.00016 wt.% results in catalysts characterized by the same catalytic activity indicating that the catalytic behaviour is determined by few very active sites, composed of Keggin anions and lacunary Keggin anions located in the supercages opened at the surface, which has a honeycomb structure. Contrary to the series of HPW/Y catalysts, HPW supported on SiO2 shows decreasing catalytic activity when its concentration lowers, the monolayer being catalytically inactive in acid–base reactions.