Effects of promotion of TiO2 with alkaline earth metals on the chemisorptive properties and water–gas shift activity of supported platinum catalysts
Effects of promotion of TiO2 with alkaline earth metals on the chemisorptive properties and water–gas shift activity of supported platinum catalysts
复制标题
DOI：
10.1016/j.apcatb.2010.11.016
复制
发表时间：
2011-01
影响因子：
22.1
通讯作者：
P. Panagiotopoulou;D. I. Kondarides
中科院分区：
文献类型：
--
作者：
P. Panagiotopoulou;D. I. Kondarides
在不同促进剂类型（M=Mg, Ca, Sr, Ba）和负载（x= 0-4wt. %）的Pt/TiO2（x%MO）催化剂上，研究了II族碱土金属促进TiO2对分散铂的化学吸附性能和水气转移（WGS）活性的影响。用CO作为探针分子进行的DRIFTS实验表明，钙的存在对Pt晶体表面的吸附没有明显的影响，但导致ν(CO)区出现新的低频带，这是由于位于金属-载体界面的电子密度增加的位点的产生和填充。H2-TPD实验结果表明，随着CaO含量的增加，这些位点对氢的吸附强度减弱。催化性能测试和动力学测量表明，碱土金属促进催化剂的活性在很大程度上取决于促进剂的性质和负载，以及用于制备掺杂tio2载体的煅烧温度。结果表明，1-2wt促进tio2负载Pt催化剂效果最佳。% CaO，其比活性是未促进催化剂的2-3倍。优化后的催化剂在实际反应条件下具有较高的活性和良好的稳定性，只要选择合适的助剂负载、煅烧温度和操作条件，就可以在实际应用中得到有效的应用。
The effects of promotion of TiO2with Group II alkaline earth metals on the chemisorptive properties and water–gas shift (WGS) activity of dispersed platinum have been investigated over Pt/TiO2(x%MO) catalysts of variable promoter type (M=Mg, Ca, Sr, Ba) and loading (x=0–4wt.%). DRIFTS experiments carried out using CO as a probe molecule showed that the presence of calcium does not affect appreciably adsorption on sites located on the surface of Pt crystallites, but results in the development of new, low-frequency bands in the ν(CO) region attributed to the creation and population of sites with increased electron density located at the metal–support interface. Results of H2-TPD experiments indicated a weakening of the adsorption strength of these sites toward hydrogen with increasing CaO content. Catalytic performance tests and kinetic measurements showed that activity of alkaline earth metal-promoted catalysts depends appreciably on the nature and loading of the promoter, as well as on the calcination temperature employed for the preparation of doped TiO2supports. Optimal results were obtained for Pt catalyst supported on TiO2promoted with 1–2wt.% CaO, the specific activity of which is 2–3 times higher, compared to that of the unpromoted catalyst. Optimized catalysts are characterized by increased activity and excellent stability under realistic reaction conditions and may be used efficiently in practical applications, provided that promoter loading, calcination temperature and operating conditions are properly selected.