Facile preparation of 3D ordered mesoporous CuOx–CeO2 with notably enhanced efficiency for the low temperature oxidation of heteroatom-containing volatile organic compounds

Abstract

SBA-16 silica with intact surface hydroxyl groups was quickly obtained (5 min) via a fast-microwave-assisted method, and further adopted as an efficient template for the synthesis of three-dimensional (3D) ordered mesoporous CuO_x–CeO₂ catalysts (htpCCx) through a simple and reproducible host–guest interaction. XRD, XPS, H₂-TPR, and Raman results reveal that many of the Cu²⁺ ions in htpCCx are incorporated into the CeO₂ lattice, leading to the formation of a Cu_xCe_1−xO_2−δ solid solution, which produces a large number of oxygen vacancies and enhances the reducibility of the metal. The interaction of Cu and Ce is essential to the reaction as it maintains the Cu²⁺/Cu¹⁺ and Ce⁴⁺/Ce³⁺ redox couples. The catalyst has a 3D mesostructure and possesses remarkably enhanced low-temperature activity for the combustion of epichlorohydrin. HtpCC20 has been identified as the most powerful catalyst for this reaction, with the reaction rate at 165 °C being about 6.3 and 33.3 times higher than those of catalysts synthesized using conventional incipient impregnation and thermal combustion methods, respectively. Furthermore, htpCC20 shows superior CO₂ selectivity (>99%) and stability (no deactivation occurs after 50 h reaction). It is believed that the dispersion of the active phase, density of surface active oxygen, and low-temperature reducibility are the dominant factors governing the catalytic performance.