High surface area La2Sn2O7 pyrochlore as a novel, active and stable support for Pd for CO oxidation

A high surface area mesoporous La2Sn2O7 compound with a well crystallized pyrochlore structure has been successfully prepared by a simple low temperature hydrothermal (La2Sn2O7-HT) method. As a support for Pd, a catalyst with a significantly higher activity for CO oxidation has been achieved in comparison with the other two non-mesoporous pyrochlores prepared by co-precipitation (La2Sn2O7-CP) and sol-gel (La2Sn2O7-SG) methods. The CO adsorption-desorption and STEM results demonstrate that on Pd/La2Sn2O7-HT, the highest Pd dispersion can be achieved among all of the catalysts. Moreover, compared with Pd/La2Sn2O7-CP and Pd/La2Sn2O7-SG, more active oxygen species were formed on Pd/La2Sn2O7-HT. It is believed that these are the two major reasons accounting for the superior CO oxidation activity of Pd/La2Sn2O7-HT. Furthermore, this catalyst also shows a stable reaction performance in the presence of water vapour. In conclusion, the mesoporous La2Sn2O7-HT pyrochlore is an excellent support for Pd, and has the potential to be applied in some real exhaust control processes.