Photoreforming: biomass upgrading in gas phase conditions

Abstract

Photoreforming is a promising technology to get hydrogen from biomass in mild conditions, using light as energy source. This reaction have been usually studied in liquid phase with noble-metal based catalysts. Throughout this work, some titanium dioxide based materials promoted with an inexpensive co-catalyst were developed for the photoreforming reaction. Two pristine materials was used: P25 Degussa and a lab-made TiO2. Then copper oxide (co-catalyst) was introduced through two techniques: wetness impregnation and deposition-precipitation (DP). Photocatalysts were then tested on a lab-made rig using ethanol-water vapor mixture as reactants and UV light as energy source. It was seen that pristine titanium dioxides yielded hydrogen by a dehydrogenation reaction and lab-prepared material shown better activity than P25. X-ray diffraction and gas physisorption analyses have showed that better performance of lab-prepared TiO2 can be attributed to pure anatase crystalline phase and higher surface area than P25. Copper promoted samples shown a higher hydrogen yield with respect to pristine ones and also to those reported on literature. It was also seen DP method gave better results than wetness impregnation with a ten-fold improve of hydrogen yield in respect to P25. Temperature Programmed Reduction analysis shown a sharper peak at lower reduction temperature for DP-prepared samples than impregnated ones, ascribing to an easy electron separation capability. Concluding we developed a cheap and easily prepared photocatalyst capable to efficiently produce hydrogen from biomass-derived fuel on gas phase.