PHOTOCATALYTIC HYDROGENATION OF ACETYLENE BY MO-2 AND MO-3 OXO SPECIES IN COLLOIDAL TIO2 SOLUTIONS

Photoreduction of Mo(V) aquo dimers and Mo(IV) aquo trimers onto colloidal TiO2 in the presence of a sacrificial electron donor (PVA) produces catalytic sites for the photoreduction of acetylene to ethane and ethylene during band gap irradiation. The Mo2 site assits in production of both ethylene and ethane while the Mo3 enhances only the ethane production. In addition, Mo2 is capable of reduction of ethylene to ethane. Quantum yields for total reducing equivalents through the Mo sites are dependent on experimental conditions but maximize at approximately 1.3% for Mo dimeric species and 0.7% for Mo trimeric species based on total incident light at λexc = 320 nm. Ethylene is also produced by direct interaction of acetylene with trapped electrons on the colloidal surface. Effects of pH, Mo loading, and intensity on the photocatalytic yields are reported. © 1990, American Chemical Society. All rights reserved.