Au/N-Ti-HMS的制备及其催化丙烯直接环氧化反应的研究  

Preparation of Au/N-Ti-HMS and the Direct Epoxidation of Propylene Using H_2 and O_2

作　　者：张文敏[1,2] 刘义武[3] 李颢[1,2] 李小强[1,2] 张小明[1] 

机构地区：[1]中国科学院成都有机化学有限公司,四川成都610041 [2]中国科学院研究生院,北京100039 [3]内江师范学院化学化工学院,四川内江641000

出　　处：《分子催化》2011年第3期213-219,共7页Journal of Molecular Catalysis(China)

基　　金：国家自然科学基金(20703039);中国科学院"西部之光"人才培养计划联合学者

摘　　要：以十二胺为模板剂合成了一系列不同Ti含量的介孔分子筛Ti-HMS,并通过高温氨处理对其进行高温改性,在分子筛表面和骨架中引入碱性N原子.分别以改性前后的Ti-HMS为载体使用沉积沉淀法制得纳米金催化剂,并考察氢气、氧气共存条件下催化丙烯气相直接环氧化的催化性能.通过氮气等温吸附-脱附、X射线衍射(XRD)、傅里叶变换红外(FT-IR)光谱、紫外-可见漫反射(DR UV-Vis)光谱、电感耦合等离子体原子发射光谱法(ICP-AES)及高倍透射电镜(HRTEM)对载体及纳米金催化剂进行了表征.结果表明:合成的Ti-HMS分子筛试样具有典型的六方介孔特征,Ti以骨架四配位状态存在.以850℃高温氮化改性Ti-HMS为载体制备的纳米金催化剂,在常压、100℃条件下,催化丙烯环氧化,反应30 min后,丙烯的转化率达6.28%,环氧丙烷的选择性为83.10%;反应270 min后丙烯的转化率降至4.74%,环氧丙烷的选择性为82.49%.经高温改性处理后,催化剂的活性及稳定性都得到了大幅度提高.Titanium-containing hexagonal mesoporous silicas（Ti-HMS） with different Ti contents have been prepared using dodecyla mine as template.Nitrogen-incorporated Ti-HMS molecular sieves were prepared by NH3 at high temperature.Au catalyst supported on Ti-HMS and Nitrogen-incorporated Ti-HMS were obtained by a deposition-precioitation method.The catalytic performance was evaluated by the direct gas phase epoxidation of propylene using hydrogen and oxygen.The samples were characterized by nitrogen isothermal adsorption-desorption,XRD,FT-IR,DR UV-Vis,ICP-AES and HRTEM.The results showed that Ti-HMS molecular sieves were hexagonal mesoporous in structure.Titanium species existed in tetra-coordinated state.Superior performance was obtained with the Au catalyst supported on Ti-HMS was modified by NH3 at 850 ℃.6.28% of propylene conversion,and 83.10% of PO selectivity can be obtained at 373 K in the initial 30 min of time-on-stream.The propylene conversion and PO selectivity were 4.74 and 82.49% after running 270 min.The performance of the Au catalyst for propylene epoxidation was improved by N-modified of the Ti-HMS supports.

关 键 词：TI-HMS 氮化作用 纳米金催化剂 丙烯环氧化 

分 类 号：O543.32[理学—物理]