Mesoporous Cu-Ce-Ox Solid Solutions from Spray Pyrolysis for Superior Low-Temperature CO Oxidation.

Abstract

Development of Pt group metal-free catalysts for low-temperature CO oxidation remains critical. In this work, active and stable mesoporous Cu-Ce-Ox solid solutions are prepared by using spray pyrolysis. The specific surface areas and pore volumes reach as high as 170 m2 g-1 and 0.24 cm3 g-1 , respectively. The results of CO oxidation study suggest that (1) the catalyst obtained by spray pyrolysis possesses much higher activity than those made by co-precipitation, sol-gel, and hydrothermal methods; (2) the optimal Cu0.2 -Ce0.8 -Ox solid solution presents a reactivity over 28 times that of both single-component CuO and CeO2 at 70 °C. Based on the study of pure-phase Cu-Ce-Ox solid solutions by selective leaching of segregated CuOx species, the active center for CO oxidation is confirmed as the bimetallic Cu-Ce-O site, whereas the individual CuOx particles not only act as spectators but also block the active Cu-Ce-O sites. A low apparent activation energy of approximately 48 kJ mol-1 is detected for CO oxidation at the Cu-Ce-O site, making Cu-Ce-Ox solid solutions able to present high activity at low temperature. Furthermore, the Cu-Ce-Ox catalysts exhibit excellent stability and thermal tolerance toward CO oxidation.