低贵金属Pt-Rh型三效催化剂空燃比性能的研究

研究了以浸渍法制备的低贵金属Pt-Rh型三效催化剂对C₃H₈, CO, NO的催化活性. 主要考察了CeO₂-ZrO₂和BaO的添加对催化剂空燃比性能的影响, 通过氧化反应、水气变换和蒸汽重整的性能研究, 探讨了催化剂三效工作窗口扩大的原因. 结果表明, 催化剂中只添加CeO₂-ZrO₂时即具有优异的水气变换性能, 蒸汽重整在250 ℃左右发生, 并且在450 ℃以下时C₃H₈的转化率一直保持在20%左右; BaO添加到含有CeO₂-ZrO₂的催化剂中对水气变换和蒸汽重整则有明显的促进作用, 能进一步扩大催化剂的三效工作窗口; 催化剂中只添加CeO₂-ZrO₂时, 能明显提高催化剂对CO的氧化反应活性, 但对C₃H₈的氧化反应的影响则不明显; BaO和CeO₂-ZrO₂同时存在于催化剂中时, 能进一步提高CO的氧化反应活性, 对C₃H₈的氧化反应则没有明显的促进作用.

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 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.