Activity of calcined Ag,Cu,Au/TiO<inf>2</inf> catalysts in the dehydrogenation/dehydration of ethanol

Abstract The catalytic activity of the anatase TiO<inf>2</inf> and M z+/TiO<inf>2</inf> with supported ions M z+ = Ag+, Cu2+, Au3+ in vapor phase conversions of ethanol is investigated at temperatures of 100-400°C. It is shown that the yields of acetaldehyde and ethylene decline for the most active catalyst Cu2+/TiO<inf>2</inf> but increase for TiO<inf>2</inf> and Ag/TiO<inf>2</inf>. The drop in the activation energy of the dehydrogenation reaction over calcined samples is linearly correlated with the one in the reduction potential of M z+ to Cu+, Au+, Ag0 and the ionic radius of M z+ in the crystal. The energies of activation for ethylene formation change in the series TiO<inf>2</inf> > Au3+ > Cu2+ >Ag+ and TiO<inf>2</inf> ≈ Cu2+ ≈ Ag+ > Au3+ for the calcined samples. The rate of pyridine adsorption, considered as an indicator of the activity of acid sites, is a linear function of ion charge +z = 1, 2, 3, and slows by two-thirds after calcination. © 2015 Pleiades Publishing, Ltd.