Metal-organic framework derived hollow CuO/CeO2 nano-sphere: To expose more highly dispersed Cu-O-Ce interface for enhancing preferential CO oxidation

Abstract

Derivation of CuO/CeO2 catalyst from metal-organic framework (MOF) precursor is able to facilitate the dispersion of active sites, resulting in an enhanced catalytic performance for preferential CO oxidation in H2-rich stream (CO-PROX). However, parts of the Cu-O-Ce active interfaces are usually sintered inside the catalyst, which will reduce the catalytic performance. To solve such problem and fully expose the catalytic active sites, herein, we design and synthesize a hollow spherical CeO2 supporting Cu3(BTC)2 precursor shell and then pyrolyze it to generate CuO/CeO2-S catalyst. The results demonstrated by the various characterizations such as PXRD, TEM, H2-TPR, O2-TPD, Raman and XPS are as follows: The quantitative Cu active species are achieved by controlling the loading layer of MOFs; The hollow structure can avoid the active Cu-O-Ce interface being coated inside; The CeO2-S provides the lowest loading energy of Cu and more oxygen vacancy. Further in-situ analysis of Raman and DRIFTs as well as kinetic detects exhibit the highest interfacial active Cu species ratio and Ce3+ concentration of the CuO/CeO2-S, comparing to catalysts with diverse morphologies and traditional impregnation method from MOF precursors. The as-synthesized CuO/CeO2-S-10-700 displays nearly 100% CO conversion at ca. 80 °C and outstanding stability for CO-PROX.