The sonochemical approach improves the CuO–ZnO/TiO2 catalyst for WGS reaction

Abstract

The CuO–ZnO composite was deposited onto two kinds of titania supports, which are synthetic mesoporous TiO₂ and commercial TiO₂ P25 (Degussa), via the ultrasound assisted precipitation and incipient wetness impregnation (IWI) methods, respectively. The catalysts were tested for WGS reaction in the temperature range of 200–400 °C, and the best catalytic performance was achieved for the sonochemically prepared catalysts supported on the commercial TiO₂ P25, which contains well crystallized anatase and rutile phases. Although the synthetic mesoporous TiO₂ has a higher surface area, its textural structure is not stable under the reaction conditions, leading to gradual deactivation of the CuO–ZnO/TiO₂ catalyst. It is found that the sonochemical preparation offers at least two advantages: (1) generation of mesopores on the catalyst surface and (2) doping of ZnO into the CuO phase. The doping of ZnO, particularly in the case of commercial TiO₂ P25, provides high activity and extra stability to the active phase of Cu⁰. These new findings provide new insights into the design and development of better heterogeneous catalysts for WGS reaction.