【作者】 王军；

【导师】 姚小泉；

【作者基本信息】 南京航空航天大学 ， 有机化学， 2019， 硕士

【摘要】 环氧化合物是重要的有机合成中间体,在制药,精细化工等领域中有着广泛的应用。其中,环氧环己烷,是一种带香味的无色或淡黄色液体,是农药杀螨剂的主要原料,也是表面活性剂,橡胶助剂,可用于合成树脂、胶粘剂等。传统的环氧化工艺如卤醇法,过酸法等,存在环境污染、设备腐蚀,工艺复杂,效率低下等缺陷,随着工业生产对环氧化工艺要求的不断增高,传统的定量氧化法正逐渐被更为绿色清洁的催化氧化工艺所淘汰。氧气是最为清洁廉价的理想氧源,但工业上除乙烯外,其他环氧化合物很难通过氧气直接高选择性的氧化对应烯烃得到。因此,研制出一种高效、稳定的、可循环的多相催化剂能够在温和条件下直接利用氧气高转化率高选择性的实现烯烃的环氧化反应,是一个十分有意义的课题。本文通过浸渍焙烧法制备了包括Ti-g-C₃N₄,Co-g-C₃N₄,Fe-g-C₃N₄,Cu-g-C₃N₄,CuNPs/g-C₃N₄等多种金属碳氮材料,并通过TEM、SEM、XRD、XPS、BET、FT-IR、EPR等现代分析测试手段对其中的一种新型金属碳氮材料Ti-g-C₃N₄进行了详细的表征。在以氧气为氧源的环己烯环氧化实验中,相比于其他金属碳氮材料,Ti-g-C₃N₄有着更好的催化活性;经过进一步的优化探索,发现在以Ti-g-C₃N₄-1为催化剂,氧气为氧源,乙腈为溶剂,异丁醛为牺牲剂,反应8小时的条件下,体系的催化效果最优,环己烯的转化率可达97%,环氧环己烷的选择性可达95%。在该最优条件下,本文还考察了其他烯烃底物的环氧化效果以及该催化剂的循环性能。结合表征结果与相关文献报道,发现催化剂的活性可能来源于Ti-g-C₃N₄材料中三价钛物种能够可逆结合并活化氧气的独特能力,并据此给出了可能的反应机理。另外,本文利用Cu/g-C₃N₄催化剂,成功开发了一种烯烃光催化环氧化的新体系,该体系十分简单,原料经济,且具有良好的反应效率。最后,为拓展Ti-g-C₃N₄催化剂的应用,本文还研究了该催化剂对于乙苯的液相选择性氧化反应的催化效果,并详细探讨了Co-N-C催化的芳烃侧链选择性氧化的反应机理,结合一系列控制实验和相关表征结果,确定了催化剂中的活性物种,为该材料在催化领域更广泛的应用提供了理论支撑。更多还原

【Abstract】 Epoxy compounds are important intermediates of organic synthesis,which are widely applied in pharmaceutical,fine chemical and other fields.Cyclohexene oxide is a kind of odorous colorless or light yellow liquid,which is the main raw material of pesticide insecticides,surfactant and rubber auxiliary,and it also can be used in synthetic resin,adhesive and so on.Traditionally,epoxidation processes were carried out with stoichiometric oxidants,such as halogen or peracid.However,those methods have the defects of environmental pollution,equipment corrosion,complex process and low efficiency,etc.;With the development of the epoxy strategy,these directly oxidations are being discouraged in favor of catalytic processes.Oxygen is the most clean and inexpensive oxygen source,but in industry,except ethylene,other epoxy compounds are difficult to obtained by directly oxidizing corresponding olefins thorugh oxygen.Therefore,it is of great significance to develop an efficient,stable and cyclic heterogeneous catalyst which can achieve olefins epoxidation by directly using of oxygen under mild conditions with high conversion and selectivity.In this paper,various metal carbon-nitrogen materials including Ti-g-C₃N₄,Co-g-C₃N₄,Fe-g-C₃N₄,Cu-g-C₃N₄,CuNPs/g-C₃N₄,etc.were prepared by impregnation calcination method.and among which,Ti-g-C₃N₄ as one of the new materials was characterized characteristed by TEM,SEM,XRD,XPS,BET,FT-IR and EPR in detail.It was found that Ti-g-C₃N₄ has better catalytic activity than other metal carbon-nitrogen materials in the cyclohexene epoxidation experiment.And after adjusting a series of reaction conditions,the optimal condition is determined as Ti-g-C₃N₄-1 used as catalyst,oxygen used as oxygen source,acetonitrile used as solvent and isobutyraldehyde used as sacrificial agent,for 8 hours reaction,the conversion of cyclohexene is up to 97%and the selectivity of cyclohexene is up to 95%.Moreover,the material has good catalytic activity for some other olefin substrates and has excellent recycling performance.Combined with the characterization results and related literature reports,it is found that the activity of the catalyst may be derived from the unique ability of the trivalent titanium species in Ti-g-C₃N₄ material to activate oxygen,and the possible reaction mechanism is given accordingly.Moreover,a new photocatalytic epoxidation system of olefins has been successfully developed using Cu/g-C₃N₄ as catalyst,the system is convenient,economical and has good reaction efficiency.Finally,in order to expand the application of the catalyst,the catalytic effect of Ti-g-C₃N₄ on the liquid phase selective oxidation of ethylbenzene was studied,and.the mechanism of the reaction of selective oxidation of aromatic side chains catalyzed by Co-N-C was discussed in detail;With a series of control experiments and related characterization results,the active species in the catalyst was determined,which provided theoretical support for the wider application of this material in the field of catalysis.更多还原