Mesoporous Y2Sn2O7 pyrochlore with exposed (111) facets: an active and stable catalyst for CO oxidation

Pyrochlore with an A(2)B(2)O(7) crystal structure is a perfect mixed oxide for catalytic application for its high thermal stability. In the present manuscript, mesoporous Y2Sn2O7 pyrochlore with exposed (111) facets was successfully synthesized via a simple hydrothermal method and used for CO oxidation. In comparison with Y2Sn2O7 prepared by a co-precipitation method (Y2Sn2O7-CP), Y2Sn2O7 prepared by a hydrothermal method (Y2Sn2O7-HT) showed superior catalytic performance for CO oxidation. Even after calcination at 800 degrees C for 4 h (Y2Sn2O7-HT-800), its catalytic performance was still better than that of Y2Sn2O7-CP. Y2Sn2O7-HT is also a good support for Pd nanoparticles. Pd/Y2Sn2O7-HT demonstrates the best performance for CO oxidation among all the catalysts. All the samples were characterized by XRD, SEM, TEM, HAADF-STEM Mapping, N-2 adsorption/desorption, H-2-TPR, CO-TPD and Raman spectra to reveal their physicochemical properties. Compared with Y2Sn2O7-CP, Y2Sn2O7-HT has more exposed (111) facets, possesses a higher amount of active surface oxygen species and had high mesoporous surface areas, which should be the reasons accounting for the superior CO oxidation performance of Y2Sn2O7-HT and Pd/Y2Sn2O7-HT. Pd/Y2Sn2O7-HT also shows superior water-tolerance. In wet feed, its catalytic activity was even better than that in dry feed. Therefore, Pd/Y2Sn2O7-HT may be a potential catalyst for practical vehicle emission control.