Production of H₂ by Ethanol Photoreforming on Au/TiO₂

Abstract

A deposition‐precipitation method is used to prepare Au/TiO 2 solids (0.45–1.7 wt% Au). These materials, consisting of gold nanoparticles (diameter range = 1.5–6.5 nm) supported on the surface of TiO 2 , are used as photocatalysts for the ethanol photoreforming reaction under either UV‐rich or simulated solar light. The main products of such reactions are H 2 in the gas phase and acetaldehyde in the liquid phase according to the reaction CH 3 CH 2 OH → CH 3 CHO ‐ H 2 . Among the gaseous products, H 2 amounts to around or above 99% in all cases; other minor products found in the gas phase are, in decreasing order of molar production: CH 4 > CO > C 2 H 4 > CO 2 > C 2 H 6 > C 3 H 8 . The photoactivity is lower under CO 2 atmosphere, as compared to analogous reactions performed under Ar. The H 2 production yields are very high (up to a maximum 30 mmol g cat −1 h −1 ) under UV irradiation, and increase with increasing gold loading. The reactions under simulated solar light also yield significant amounts of H 2 (5–6 mmol g cat −1 h −1 ) as the main gaseous product.