A Study of Low-Temperature CO Oxidation over Mesoporous CuO-TiO2 Nanotube Catalysts

Supported copper oxide nanoparticles have attracted considerable attention as active and non-precious catalysts for many catalytic oxidation reactions. Herein, mesoporous xCuO-TiO2 nanotube catalysts were fabricated, and their activity and kinetics toward CO oxidation were studied. The morphology and structure of the prepared catalysts were systematically studied using SEM, TEM, EDS, EDX, XRD, TGA, BET, XPS, H2-TPR, and Raman techniques. The BET surface area study revealed the effect of the large surface area of the mesoporous TiO2 nanotubes on promoting the catalytic activity of prepared catalysts. The results also revealed the existence of strong metal-support interactions in the CuO-TiO2 nanotube catalyst, as indicated by the up-shift of the E2g vibrational mode of TiO2 from 144 cm−1 to 145 cm−1 and the down-shift of the binding energy (BE) of Ti 2p3/2 from 458.3 eV to 458.1 eV. The active phase of the catalyst consists of fine CuO nanoparticles dispersed on a mesoporous anatase TiO2 nanotube support. The 50-CuO-TiO2 nanotube catalyst demonstrated the highest catalytic activity with 100% CO conversion at T100 = 155 ◦C and a reaction rate of 36 μmole s−1 g−1. Furthermore, the catalyst demonstrated excellent long-term stability with complete CO conversion that was stable for 60 h under a continuous stream. The enhanced catalytic activity is attributed to the interplay at the interface between the active CuO phase and the TiO2 nanotubes support.