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 C₃H₈ began to occur at 250 ℃ and maintained 20% of the conversion of C₃H₈ before 450 ℃. 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 C₃H₈ was not obvious. Catalyst containing BaO and CeO₂-ZrO₂ could further promote oxidation reaction activity of CO but did not obviously promote oxidation of C₃H₈.

Key words: Pt-Rh, three-way catalyst, water-gas shift, steam reforming