载体SiO_2表面修饰对钒基催化剂丙烷氧化脱氢催化性能的影响  

The Influence of Pre supported MgO over SiO 2 on Catalytic Performance of Supported Vanadia base Catalysts for Propane Oxidative Dehydrogenation

作　　者：陈明树[1] 翁维正[1] 万惠霖[1] 许翩翩[1] 

机构地区：[1]厦门大学化学系物理化学研究所固体表面物理化学国家重点实验室

出　　处：《厦门大学学报（自然科学版）》1999年第4期556-561,共6页Journal of Xiamen University：Natural Science

基　　金：国家科技部攀登预选项目;教育部高等学校博士学科点专项科研基金

摘　　要：用ＸＲＤ、Ｒａｍａｎ、ＦＴ－ＩＲ、５１Ｖ－ＮＭＲ、Ｐｙ－ＩＲ和ＴＰＲ－ＴＰＯ表征ＳｉＯ２或ＳｉＯ２上预负载ＭｇＯ后负载的钒氧化物催化剂体系．ＳｉＯ２上直接负载钒氧化物，在钒负载量约为５ｗｔ％Ｖ２Ｏ５时出现Ｖ２Ｏ５晶相，而预负载ＭｇＯ的在相同钒含量时则没有出现Ｖ２Ｏ５晶相，表明预负载ＭｇＯ促进了钒氧化物在载体表面的分散．预负载ＭｇＯ的催化剂的可还原性和其还原态活化气相氧的活性较低，有较好的丙烷氧化脱氢的丙烯选择性，同时又因有较强的表面酸性位，有利于对丙烷仲碳Ｃ－Ｈ键的活化，而能保持其较高的丙烷氧化脱氢活性．钒氧物种与载体形成Ｖ－Ｏ－Ｍｇ（Ｓｉ）桥键。The SiO 2 and MgO/SiO 2 supported vanadia base catalysts were characterized by XRD, Raman, FT IR, 51 V NMR, Py IR and TPR TPO. The results showed that the vanadia were highly dispersed on the MgO pre supported V 2O 5/MgO/SiO 2 catalysts, while vanadia phase was detected in the direct supported V 2O 5/SiO 2 catalysts. The reducibility and reoxidability of the V 2O 5/MgO/SiO 2 catalysts are weaker than that of V 2O 5/SiO 2 catalysts, thus displaying higher propene selectivity. In the other hand, the surface acid sites of V 2O 5/MgO/SiO 2 catalysts were more and stronger, which are favorable to activating the second (2°) C H bond in propane molecular, and thus increasing the activity of propane oxidehydrogenation. The bridge oxygen species (V O Mg/or Si) might be the active oxygen species for propane oxidehydrogenation.

关 键 词：钒氧化物 丙烷 氧化脱氢 钒基催化剂 催化性能 

分 类 号：O623.11[理学—有机化学] O643.36[理学—化学]