Low-temperature removal of toluene and propanal over highly active mesoporous CuCeOx catalysts synthesized via a simple self-precipitation protocol

Abstract

A series of CuCeOx binary oxide catalysts with high specific surface area and mesoporous structure were synthesized by a facile self-precipitation approach. Toluene and propanal were adopted as the probe pollutants to evaluate their catalytic performance. The techniques such as XRD, N2 adsorption/desorption, FE-SEM, TEM, H2-TPR, XPS, Raman, DRUV–vis, and XANES, were employed for catalyst characterization. It is shown that plenty of Cu2+ ions in mesoporous CuCeOx oxides are incorporated into CeO2 lattice in the form of CuxCe1−xO2−δ solid solution, which produces large amounts of oxygen vacancies in the interface of CuOx and CeO2 oxides. Meanwhile, the Cu2+-O2−-Ce4+ connection in the solid solution can act as a bridge for oxygen transfer between Cu and Ce, and enhance the reducibility of both components. The activity of mesoporous CuCeOx catalysts exhibits a volcano-type behavior with the increase of the Cu content, and the sample with Cu/Ce atomic ratio of 3/7 exhibits the highest catalytic efficiency. At GHSV of 36,000h−1, the temperatures for 90% toluene and propanal conversion over Cu0.3Ce0.7Ox sample are 212 and 192°C, respectively, which are much lower than the catalysts synthesized via the incipient impregnation and thermal combustion methods. The co-combustion result demonstrates that propanal oxidation can be remarkably suppressed by the introduction of toluene due to the stronger surface affinity of toluene molecules. It can be concluded that both the higher surface oxygen adspeices concentration and better low-temperature reducibility were responsible for the superior activity of mesoporous CuCeOx catalysts.