Improvement of Pd Dispersion and Purification Performance of NGVs Exhaust of Pd/CeCoO_x Catalyst

Recent research on three-way catalyst development for natural gas vehicles (NGVs) exhaust gas purification has been focusing on the high dispersion of loaded noble metal on catalysts. In this paper, nanostructured CeCoOx composited oxide support was prepared by metal organic frameworks (MOFs) template method and compared with cerium-cobalt oxides prepared by the conventional sol-gel (SG) method, which were used to investigate the dispersion state of noble metal Pd on the two catalyst supports and its influence on the catalytic performance. The results showed that the CO, NO and CH4 three-way catalytic temperatures (at the same conversion) of Pd/CeCoOx(M) catalyst derived from CeCo-MOFs material are about 100 degrees C lower than that of Pd/CeCoOx(SG) catalyst with the same chemical composition, and Pd/CeCoOx(M) has higher low-temperature activity. The cerium-cobalt composite oxide derived from CeCo-MOFs has smaller crystal particles, uniform crystalline phase structure, and larger specific surface area, which promotes the dispersion state of Pd components and also enriches the oxygen vacancies and structural defects of the catalysts, so significantly improving the low-temperature three-way catalyst performance. The results indicate that the composite oxide obtained by thermal decomposition of MOFs precursor can be used as a good material for the active noble metal dispersion of three-way catalyst.