Oxidative dehydrogenation of ethanol over Au/TiO 2 photocatalysts

Abstract

Au/TiO 2 photocatalysts were used in ethanol oxidative dehydrogenation. Catalysts at gold loading ranging between 0.5-2 wt.% were synthesized by photodeposition (using different deposition times: 15 and 120 min) over an ownprepared TiO 2 by sol-gel method. For reference purposes, a commercial 1 wt.% Au/TiO 2 catalyst (AUROlite ™, Strem Chemicals) was also tested. Photocatalytic reactions were carried out in a gas-solid photocatalytic fluidized bed reactor. Catalytic activity depends strongly both on Au loading and on the material properties, such as particle size and distribution of metal on titania surface. Acetaldehyde was the main reaction product, with ethylene, crotonaldehyde and CO 2 as by-products. An important improvement of TiO 2 photoactivity was achieved for the catalyst with 0.5 wt.% gold prepared with 120 min deposition time. For an ethanol inlet concentration of 0.2 vol% at 60°C, the maximum conversion and acetaldehyde selectivity were 82% and 95%, respectively. These values are considerably higher than those obtained over pristine TiO 2 and over the commercial catalyst. © 2012 Science & Technology Network, Inc.