摘要
利用单管模式催化剂评价装置、X光电子能谱分析 (XPS)、吡啶程序升温脱附 (TPD)等方法 ,研究了碱金属助剂Rb对邻二甲苯氧化制苯酐 (PA)V Ti型催化剂性能的影响。采用XPS的数据 ,以半定量方法计算钒(V)相在二氧化钛 (TiO2 )表面的表面浓度。结果表明 ,碱金属Rb可改善V物种在TiO2 表面的分散性 ,减少活性中心的富集。TPD测定结果表明 ,添加碱金属Rb助剂会影响催化剂的表面酸性 ,降低强酸位的吸附 ,改变催化活性中心的电子性质。当Rb添加量适当时 ,可获得较高的苯酐选择性。
Investigation was conducted on V or V doped with Rb used as oxidation catalysts for producing phthalic anhydride (RA) from o-xylene. Characterization was performed by using a bench scale catalyst evaluation unit, XPS and TPD (pyridine as the adsorbate) methods to investigate the role of alkali metal Rb functioning as a promoter to enhance the catalytic behaviors of V-Ti type catalyst. Based on XPS data, semi-quantitative method was employed to calculate the relative surface concentration of vanadium (V) dispersed on titania (TiO2) and the atomic ratio nV:nTi. Results showed that the addition of Rb alleviated the aggregation of the dispersing [V] active centers on TiO2 surface, and a higher selectivity of PA on Rb-V-Ti catalyst was also observed. Surface acidity of these catalysts measured by TPD showed its changes. The decrease of the stronger acid-sites due to the addition of Rb resulted in the improvements of selectivity for PA.
出处
《石油学报（石油加工）》
EI
CAS
CSCD
北大核心
2001年第5期36-41,共6页
Acta Petrolei Sinica(Petroleum Processing Section)
关键词
碱金属
铷
邻二甲苯
苯酐
氧化
催化剂
性能
Alkali metals
Catalyst selectivity
Catalysts
Rubidium
Titanium dioxide
X ray photoelectron spectroscopy
Xylene
