Dual templates assisted preparation and characterization of highly thermostable multicomponent mesoporous material La-Ce-Co-Zr-O used for low-temperature CO oxidation

摘要

The multicomponent materials La-Ce-Co-Zr-O were first prepared by using mixed surfactants comprised of p-octyl polyethylene glycol phenyl ether (OP) and cetyltrimethyl-ammonium bromide (CTAB) as co-templates, which show large specific surface areas (up to 163 m(2)/g) and uniform pore size distributions (3.4-3.6 nm) after calcination at 500 degrees C. High-resolution transmission electron microscopy (HR-TEM) image shows that these materials possess wormhole-like mesoporous structures. N-2 adsorption/desorption indicates that the coexistence of La and Ce in a proper atomic ratio is very crucial to improve the thermal stability of these mesoporous materials. The catalyst with La/Ce atomic ratio of 1/16 exhibits the best thermal stability. After calcination at 700 degrees C, its specific surface area is still up to 54 m(2)/g, much larger than those for the most reported LaCoO3-related perovskite. Temperature-programed reduction (H-2-TPR) results show that the coexistence of La and Ce in a ratio of 1/16 can bring more profound Co-Ce interaction and the highest mobility of Co-O bond in the catalyst calcined at 700 degrees C. The mesoporous material La-Ce-Co-Zr-O with La/Ce atomic ratio of 1/16 exhibits not only high-thermal stability, but also novel catalytic activity for CO oxidation.