纳米碳纤维的微观结构及对丙烷氧化脱氢反应的催化性能  

Microstructure of Carbon Nanofibers and Their Catalytic Performance for Oxidative Dehydrogenation of Propane

作　　者：隋志军[1] 赵铁均[1] 周静红[1] 李平[1] 戴迎春[1] 

机构地区：[1]华东理工大学化学工程联合国家重点实验室,上海200237

出　　处：《催化学报》2005年第6期521-526,共6页

基　　金：国家自然科学基金资助项目(20376021)

摘　　要：采用化学气相沉积法制备了具有不同微观结构的纳米碳纤维,并用丙烷程序升温吸脱附和热重实验对纳米碳纤维进行了表征,考察了纳米碳纤维在丙烷氧化脱氢反应中的催化性能.结果表明,纳米碳纤维表面的含氧基团可能是催化活性中心;纳米碳纤维不仅具有较好的催化性能,而且在反应条件下具有较高的热稳定性.在550℃下,鱼骨式纳米碳纤维上丙烷转化率为44·9%时,丙烯选择性为33·0%,其催化性能与V-Mg-O等金属氧化物催化剂相当.不同微观结构纳米碳纤维的催化性能相差较大,这是由于其表面化学性质不同所致.Carbon nanofibers (CNFs) with different microstructure were synthesized by chemical vapor deposition method and treated in argon at 1 700 degrees C for 12 h. The CNFs were used as catalysts for oxidative dehydrogenation of propane (ODP). The fish-bone CNF (F-CNF) had good performance for the reaction, showing propane conversion of 44.9% and propene selectivity of 33.0% at 550 degrees C. But, the catalytic performance over tubular CNF (T-CNF) was much lower than that over F-CNF. Raising the reaction temperature was favorable for achieving high propene yield. The TEM, XRD, N-2-adsorption and Boehm titration were carried out to characterize the structure and surface property of the CNFs. The most obvious structure difference was that the graphite layer of F-CNF had 5 degrees similar to 10 degrees angles to the axis, which would lead to different ratios of edge carbon atoms to basal carbon atoms. The carbon atoms at these two sites had different functions for ODP, especially for the process of oxygen transformation. F-CNF had more edge carbon atoms than T-CNF, which could combine with oxygen to form surface oxygen complexes. This could be confirmed by comparing the amounts of surface carbonyl groups. Temperature-programmed adsorption-desorption of propane over CNFs testified that the surface oxygen complexes played a key role in conversion of propane to propene. The structure stability of CNFs was characterized by TG in the reaction atmosphere.

关 键 词：纳米碳纤维 微观结构 丙烷 氧化脱氢 丙烯 程序升温吸脱附 

分 类 号：O621.251[理学—有机化学]