本文選題：摻氮碳納米管 + 非金屬催化劑��； 參考：《湘潭大學》2017年碩士論文

【摘要】：加氫反應的活性組分一般為金屬,使用最廣泛的催化劑是負載型貴金屬催化劑,但由于貴金屬的價格高,許多學者開始研究低成本的銅、鎳等非貴金屬負載型催化劑用于加氫反應。碳納米管擁有良好的導電性,導熱性,穩(wěn)定性和高機械強度,是一種良好的催化劑載體,而雜原子摻雜的碳納米管可以作為一種非金屬催化劑催化氧還原反應,為雜原子摻雜碳納米管應用在催化加氫反應中提供了新的思路。本工作制備了一類非金屬摻氮碳納米管催化劑,考察了不同催化劑對硝基化合物加氫反應的催化性能,并對這些催化劑進行表征,分析催化劑的“構-效”關系,同時優(yōu)化了反應條件。本工作分別通過CVD法和后處理摻雜法兩種方法制備摻氮碳納米管,并對兩種不同方法制備的氮摻雜碳納米管的微觀結構進行對比,發(fā)現(xiàn)CVD法制備的摻氮碳納米管呈竹節(jié)狀,在進行了探針反應后,發(fā)現(xiàn)CVD法合成的摻氮碳納米管對加氫反應沒有活性,所以本工作選用后處理摻雜法制備的摻氮碳納米管用于加氫反應的研究。探討了摻氮碳納米管對1,5二硝基萘,硝基萘以及硝基苯加氫的催化性能,1,5二硝基萘在摻氮碳納米管的催化作用下可以加氫生成1,5二氨基萘,但是選擇性很低;摻氮碳納米管在硝基萘加氫反應中同樣表現(xiàn)出了一定的加氫活性,產(chǎn)物萘胺的選擇性偏低,摻氮碳納米管催化硝基苯加氫,產(chǎn)物苯胺的選擇性可達90%以上,通過比較分析確定最優(yōu)的催化劑為800℃下后處理摻雜制備的m-ONCNTs-800摻氮碳納米管。本工作對摻氮碳納米管催化硝基苯加氫反應進行了深入的研究,使用m-ON CNTs-800催化劑,優(yōu)化了硝基苯加氫的反應條件,在170℃下,硝基苯用量1g,催化劑用量為0.1g,乙醇20ml,氫壓4 MPa,反應時間8h時,硝基苯轉化率為59.74%,選擇性可達到91.48%。通過設計實驗與表征分析排除了摻氮碳納米管中殘留的金屬對催化劑加氫活性的影響,確定了摻氮碳納米管催化加氫是非金屬催化,通過分析得到在硝基苯加氫反應四方氮與吡啶型氮可能是影響催化性能的活性中心。本工作采用MS軟件對摻氮碳納米管進行模擬計算,發(fā)現(xiàn)氮原子的摻雜會改變碳納米管的LUMO和HOMO軌道,摻雜的氮原子上具有更高的電負性,周圍的碳原子都帶有明顯的正電荷,說明氮原子摻雜的碳納米管在雜質氮原子附近位置的化學活性較高。計算結果表明氮摻雜的碳納米管和H2之間的吸附為化學吸附,未摻雜的碳納米管與H2分子較難生成化學鍵。
[Abstract]:The active component of hydrogenation reaction is usually metal. The most widely used catalyst is supported noble metal catalyst. However, due to the high price of precious metal, many scholars have begun to study low cost copper. Nickel and other non-noble metal supported catalysts are used for hydrogenation. Carbon nanotubes (CNTs) have good electrical conductivity, thermal conductivity, stability and high mechanical strength, so they are a good catalyst carrier, while hetero-atom-doped CNTs can be used as a non-metallic catalyst to catalyze oxygen reduction. It provides a new idea for the application of hetero-atom doped carbon nanotubes in catalytic hydrogenation. In this work, a class of non-metallic nitrogen-doped carbon nanotube catalysts were prepared. The catalytic properties of different catalysts for hydrogenation of nitro compounds were investigated, and these catalysts were characterized to analyze the "structure-activity" relationship of the catalysts. At the same time, the reaction conditions were optimized. In this work, nitrogen-doped carbon nanotubes (NCNTs) were prepared by CVD method and post-treatment doping method, respectively. The microstructure of nitrogen-doped CNTs prepared by two different methods was compared. It was found that the nitrogen-doped CNTs prepared by CVD method were bamboo-shaped. After the probe reaction, it was found that the nitrogen-doped carbon nanotubes synthesized by CVD method had no activity for hydrogenation, so the nitrogen-doped carbon nanotubes prepared by the post-treatment method were used in the study of hydrogenation reaction. The catalytic properties of nitrogen-doped carbon nanotubes (CNTs) for the hydrogenation of 1n 5 dinitronaphthalene, nitrone naphthalene and nitrobenzene were discussed. The hydrogenation of 1 nitro 5 dinitronaphthalene with nitrogen-doped carbon nanotubes can produce 1 N 5 diaminaphthalene, but the selectivity is very low. The nitrogen-doped carbon nanotubes also showed a certain hydrogenation activity in the hydrogenation of nitronaphthalene. The selectivity of the product naphthylamine was low, and the selectivity of aniline could reach more than 90% in the hydrogenation of nitrobenzene catalyzed by nitrogen-doped carbon nanotubes. Through comparative analysis, the optimum catalyst is the m-ONCNTs-800 nitrogen-doped carbon nanotubes doped at 800 鈩，

本文編號：1881295