Effect of different phase composition in titania on catalytic behaviors of AgLi/TiO2 catalysts via ethanol dehydrogenation

Abstract

This research was to investigate the production of acetaldehyde from ethanol by non-oxidative and oxidative dehydrogenation reaction over AgLi/TiO2 catalysts containing different phases of TiO2 supports. The catalysts were prepared via impregnation of Ag and Li onto TiO2 having different phases [anatase (A), rutile (R) and mixed phases (AR)]. The structure of different AgLi/TiO2 catalysts was confirmed using various techniques including XRD, N2 physisorption, SEM-EDX, ICP, FTIR, UV–vis spectroscopy, H2-TPR, and CO2-TPD. The results from non-oxidative dehydrogenation indicated that AgLi/TiO2-A catalyst exhibited the highest acetaldehyde yield of ca. 40 % at 300 °C, while acetaldehyde yield of ca. 66 % was obtained for AgLi/TiO2-AR catalyst at 300 °C in oxidative dehydrogenation. On the basis of experimental results, we conclude that the phases transition of TiO2 strongly affects the physicochemical properties of AgLi/TiO2 catalysts. The influence of catalyst properties such as the strength of basic sites and reduction behaviors have been a positive synergetic effect for enhancing the catalytic performance of both reactions. Reasons for these were discussed.