Pt基催化剂在富丙烯气氛中选择性氢气氧化性能和结构演变规律

The performances and structure evolution of Pt-based catalysts for selective hydrogen combustion under propene-rich conditions

本工作研究了富丙烯气氛中Pt基催化剂的SHC性能和长期使用过程中活性相的演变规律。结果发现,Sn修饰的Pt/SiO2催化剂在丙烷和丙烯同时存在的条件下具有高的氢气氧化选择性(大于98%)。通过动力学研究,稳定性测试和结构表征发现,氧气的引入能够显著提高催化剂的结焦速率,形成的高度石墨化的焦炭,Pt的烧结,PtSn合金中Sn的氧化和偏析是导致长期稳定性测试中选择性下降的主要因素。

In the present study,the kinetic behaviour and active sites evolution processes of Pt-based catalysts were investigated.It was found that highly selective hydrogen combustion could be achieved over Sn modified Pt-based catalysts in presence of both propane and propene(over 98%).The stability tests,kinetic study and catalyst characterization revealed that the existence of oxygenated species is the reason for accelerated coking reactions.The formation of graphitized cokes serving as additional unselective active sites and the oxidation of tin in PtSn alloy phases are the primary reasons causing the catalytic selectivity loss during long-run tests under propene-rich condition.