摘要
通过X射线光电子能谱和俄歇电子能谱对氧化(350℃,空气中)和还原(480℃氢气流中)状态的Pt—Ir/γ—Al_2O_3和Pt—Ir/SiO_2模型催化剂的表面特征进行了研究。试验发现,氧化状态下,样品表面上主要是PtO_2和Ir的高价氧化物以及少量PtO,还原过程使这些氧化物转化为金属,主要是以微细的金属簇的形式分散在表面上。Pt和Ir之间存在相互作用,是形成双金属簇的表现,同时还有少量由于金属烧结过程形成的较大的金属粒子,该状态下的Pt_(4f)和Ir_(4f)结合能较前者略低;SiO_2载体上的铂和铱的原子浓度与在γ—Al_20_3上有明显差异。
X-ray photoelectron spectroscopy for chemical analysis and Auger electron spectroscopy were used for characterizing thing surfacing of model Pt-Ir/ Al2O3(SiO2) catalyst after oxidation in air at 350℃ and reduction in hydrogen at 1 atm and 480℃. Results showed that reduction converted PtO2, PtO and oxide of higher valence iridum present on the surface of oxided sample to bimetallic clustes and a small amount of larger or bulk-like particles in sintering. The properties of support obviously affect the atomic concentration of supported metals and Pt4f and Ir4f binding energy of metallic platinum and irdium.
出处
《石油大学学报(自然科学版)》
CSCD
1990年第4期85-91,共7页
Journal of the University of Petroleum,China(Edition of Natural Science)
关键词
重整催化剂
表面特性
双金属催化剂
Reforming catalyst
Surface characteristics. Bimetalliccatalysts