Reduced Silver Salt of Wells-Dawson Heteropolyacid H6P2W18O62 as a Bi-Functional Catalyst

Silver salt preparation was obtained by neutralizing solution of H6P2W18O62 in water with solid Ag2CO3. In the introductory experiments the conditions of silver salt reduction with ethanol vapours were studied at 170–290 °C. At 250 °C and 2.5 h complete reduction to silver and free heteropolyacid was observed. During reduction with ethanol the initially not active salt became catalyst on which typical for free acid alcohol dehydration to ethylene occurred. In a series of experiments carried out within temperature range 210–290 °C ethanol conversion was studied on the catalyst previously reduced at 250 °C. When air was used as the carrier gas the bi-functional behavior of the catalyst was distinct, besides ethylene, diethyl ether and water, typical products of acid–base type catalytic reaction also comparable amount of acetaldehyde, the product of redox type reaction, was observed.