Palladium-based catalysts are well known for their catalytic activity in hydrocarbon oxidation reactions in exhaust emission control. There is a need to develop catalysts that perform oxidation at low temperatures (< 300 °C), especially for future high efficiency combustion engines. In the present study, we investigate the role of Pd oxidation state in this temperature range for the oxidation of three different hydrocarbons (methane, propane and propylene). For each of these hydrocarbons, the reduced Pd catalyst was more active than the same catalyst after oxidation. Furthermore, when the reduced catalyst was tested under lean conditions, the activity for hydrocarbon oxidation declined due to formation of PdO. The addition of Pt helped to maintain Pd in a reduced state, even under lean conditions, and this is a major reason for improved performance of Pt-Pd catalysts compared to Pt or Pd alone. X-ray absorption near edge spectra (XANES) and temperature programmed reduction (TPR) experiments were used along with activity testing to understand the impact of the oxidation state of Pd on hydrocarbon oxidation performance. This study provides guidance in the development and operation of Pd catalysts for low temperature hydrocarbon oxidation.

钯基催化剂因其在废气排放控制中的烃氧化反应中的催化活性而众所周知。需要开发在低温（＜300℃）下进行氧化的催化剂，特别是对于未来的高效内燃机。在本研究中，我们研究了在此温度范围内Pd氧化态对三种不同碳氢化合物（甲烷，丙烷和丙烯）的氧化作用。对于这些烃中的每一种，还原后的Pd催化剂比氧化后的相同催化剂更具活性。此外，当在稀薄条件下测试还原的催化剂时，由于PdO的形成，烃氧化活性降低。即使在稀薄的条件下，添加Pt也有助于将Pd维持在还原状态，与单独使用Pt或Pd相比，这是提高Pt-Pd催化剂性能的主要原因。使用X射线吸收近边缘光谱（XANES）和程序升温还原（TPR）实验以及活性测试来了解Pd氧化态对烃氧化性能的影响。这项研究为低温烃氧化的Pd催化剂的开发和操作提供了指导。