Behaviour of Pt/TiO2 catalysts with different morphological and structural characteristics in the photocatalytic conversion of ethanol aqueous solutions

Abstract

Pt/TiO2 catalysts with a similar Pt dispersion and different morphological and structural characteristics were prepared, characterized and used in the photocatalytic transformation of aqueous ethanol solutions at room temperature. The characteristics of the catalysts allowed the comparison of their catalytic behaviour as a function their structural and morphological properties, which determined both the amount of hydrogen produced and the nature of the carbon-containing products. The characterization techniques used include N2 physisorption, XRD, TEM, Raman, UV–vis and XP spectroscopies, H2-TPR and CO chemisorption. Temperature programmed desorption of post-reaction catalysts was followed by DRIFTS-MS. The Pt/TiO2 catalysts contained only anatase (Pt/A catalysts) or both anatase and rutile (Pt/AR catalysts), and had surface area from approximately 50 m2·g−1 to 100 m2·g−1 with mean pore sizes varying from 5 to 43 nm. Pt/TiO2 catalysts having surface area of approximately 50 m2·g−1 and mean pore size of 30–40 nm produced more H2 than the other catalysts, with Pt/A50 being the catalyst which produced the most. In all cases, the major carbon-containing products in the liquid phase were acetaldehyde, 2,3-butanediol and acetic acid. A relationship between the mean pore size and the yield of 2,3-butanediol was established with most being produced over Pt/A100 which had the smallest pore size.