Study of air/fuel ratio performance of low-precious metal Pt-Rh three-way catalysts

The catalytic activities on C3H8, CO and NO of low-precious metal of Pt-Rh three-way catalysts prepared by impregnation were studied. The influence of adding CeO2-ZrO2 and BaO into catalysts on air-to-fuel ratio (A/F) was mainly investigated. The reason that A/F was broadened was studied by oxidization reaction, water-gas shift and steam reforming over catalysts. The results indicated that the catalyst merely containing CeO2-ZrO2 had excellent ability of water-gas shift, and steam reforming of C3H8began to occur at 250°C and maintained 20% of the conversion of C3H8before 450°C. BaO was added to the catalyst containing CeO2-ZrO2, which could significantly promote water-gas shift and steam reforming and further broadened the three-way working-window of the catalyst. Only addition of CeO2-ZrO2 to the catalysts could promote oxidation reaction activity of CO, but the influence on oxidation of C3H8was not obvious. Catalyst containing BaO and CeO2-ZrO2 could further promote oxidation reaction activity of CO but did not obviously promote oxidation of C3H8.