Improvement of Pd dispersion and purification performance of NGVs exhaust on Pd/CeCoOx catalyst

Abstract:

Recent research in three-way catalyst development for natural gas vehicles (NGVs) exhaust gas purification has been focusing on the high dispersibility of loaded noble metal of 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 method (SG), 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 performance of Pd/CeCoOx(M) catalyst derived from CeCo-MOFs material was about 100 ℃ lower than that of Pd/CeCoOx(SG) catalyst with the same composition prepared by sol-gel method, and it has lower low-temperature activity. The cerium-cobalt composite oxide derived from CeCo-MOFs had smaller crystal particles and uniform crystalline phase structure with larger specific surface area, which promoted the improvement of the dispersion state of Pd components and also enriched the oxygen vacancies and structural defects of the catalysts, so significantly improving the low-temperature three-way catalyst performance. The results indicated that the composite oxide obtained by thermal decomposition of MOFs precursor can be used as a good material for the dispersion of the active components of noble metal of three-way catalyst.

Key words:NGVs exhaust purification; MOFs materials; noble metal dispersion; CeCoOx composite oxide