【作者】 陈洁；

【导师】 张胜建；

【作者基本信息】 浙江大学 ， 化学工程， 2017， 硕士

【摘要】 本文制备了三种硅烷化改性TS-1催化剂,进而考察了应用于1-己烯环氧化和丁酮氨肟化反应过程中的催化性能和催化作用机理。首先,论文介绍了制备含有硅羟基Si-OH、氨基-NH2和烷基的硅烷化改性TS-1催化剂的方法,并通过FT-IR、TG/DTG、UV-Vis、BET和元素分析表征硅烷化剂的负载情况和负载量。其次,采用UV-Vis、NH3-TPD和Py-IR分析改性TS-1加入H2O2后,Ti-OOH、Si-OH数量的变化和表面酸性的变化。进而,考察了 TS-1改性对1-己烯环氧化和丁酮氨肟化反应催化性能的影响。最后,结合表征分析结果和文献,讨论了改性TS-1催化氧化作用机理。实验结果表明,在TS-1硅烷化前采用氨水溶液进行预处理,能够提高TS-1表面的Si-OH数量,从而提高TS-1用APTES、MTES及DMDES硅烷化改性的效率,同时不改变TS-1的骨架结构和总钛含量。FT-IR、TG/DTG结果表明预处理后的TS-1通过硅烷化改性成功制备得到含有硅羟基Si-OH、氨基-NH2和烷基的改性TS-1催化剂;UV-Vis结果表明改性前后TS-1的Ti元素分布基本不变;BET分析表明改性TS-1催化剂的BET比表面积、t-plot微孔比表面积和t-plot微孔孔容均减小,说明在孔道内外都接枝了硅烷化剂;元素分析结果表明三种改性催化剂APTES/TS-1水解、MTES/TS-1水解及DMDES/TS-1水解的接枝率分别为 0.664、0.833 及 0.663 mmol/g。UV-Vis表征结果表明,三种改性TS-1中,加入H2O2后,与未改性TS-1/H2O2相比,Ti-OOH过氧活性中心稳定性和数量增加。NH3-TPD结果表明,MTES/TS-1水解和DMDES/TS-1水解加入H202后,与TS-l/H2O2相比,Ti-OOH数量增加,Si-OH的数量显著减小。Py-IR结果表明,TS-1改性会改变TS-1的表面酸性。1-己烯环氧化和丁酮氨肟化反应结果表明,三种改性TS-1催化剂均能显著提高1-己烯环氧化和丁酮氨肟化反应的转化率和选择性。未改性TS-1催化1-己烯环氧化反应的转化率为59.2%,选择性为64.1%;三种改性催化剂APTES/TS-1水解、MTES/TS-1水解及DMDES/TS-1水解催化剂催化1-己烯环氧化反应的转化率分别为69.0%、69.0%和64.7%,选择性分别为68.9%、95.4%和96.7%。未改性TS-1催化丁酮氨肟化反应的转化率为68.0%,选择性为84.3%;三种改性催化剂APTES/TS-1水解、MTES/TS-1水解及DMDES/TS-1水解催化剂催化丁酮氨肟化反应的转化率分别为71.3%、73.6%和78.0%,选择性分别为86.5%、97.5%和 99.3%。结合表征分析结果和文献,论文讨论了改性TS-1催化氧化作用机理。APTES/TS-1水解/H2O2体系中,APTES中末端氨基-NH2中的N原子与Ti-OOH中的末端H原子形成氢键,APTES/TS-1水解后引入的Si-OH与Ti-OOH中的末端O原子也形成氢键,其中以Si-OH与Ti-OOH形成的氢键作用为主,这两个氢键结构,稳定了 Ti-OOH活性中心,提高了 Ti-OOH活性中心的数量。MTES/TS-1水解/H2O2体系和DMDES/TS-1水解/H2O2体系中Si-OH末端的H原子与Ti-OOH末端的O原子形成氢键作用,使得Ti-OOH稳定性和数量增加,同时使Si-OH酸量减少。同时,硅烷化剂中有机基团也改变了催化剂表面的疏水性。这些因素综合使得硅烷化改性TS-1催化剂催化1-己烯环氧化和丁酮氨肟化反应的转化率和选择性均有显著增加。更多还原

【Abstract】 In this work,three modified TS-1 catalysts were prepared.The catalytic performance of 1-hexene epoxidation and butanone ammoximation and catalytic reaction mechanism of these three modified TS-1 catalysts were studied.Firstly,the preparation methods of modified TS-1 catalysts which contained Si-OH,-NH2 and alkyl groups were introduced.Through FT-IR,TG/DTG,UV-Vis,BET and EA,the load conditions and load amounts of modified TS-1 catalysts were characterized and analyzed.Secondly,the change of the amounts of Ti-OOH,Si-OH and surface acidity after adding H2O2 to modified TS-1 was analyzed by UV-Vis,NH3-TPD and Py-IR characterization.The influence of TS-1 modification on 1-hexene epoxidation and butanone ammoximation was investigated.Finally,combined the results of characterization and analysis with literature,the catalytic mechanisms of modified TS-1 were discussed.Experiments results showed that adopted ammonia solution to pretreat TS-1 catalysts could improve the Si-OH amounts on TS-1 surface,thus promote the efficiency of TS-1 silanization and not change the skeleton structure and total Ti content of TS-1.FT-IR and TG/DTG results showed that modified TS-1 catalysts which contained Si-OH,-NH2 and alkyl groups could be successfully prepared through the silanization of pretreated TS-1.UV-Vis results showed that the Ti element distribution of TS-1 was unchanged before and after modification.BET results showed that the BET specific surface area,micropore specific surface area and micropore volume after modification were all decreased,indicating the grafting of silylating reagents on TS-1 surface or internal micropores.Element analysis indicated that the grafting rate of hydrolyzation of APTES/TS-1,hydrolyzation of MTES/TS-1 and hydrolyzation of DMDES/TS-1 were respect:ively 0.664,0.833 and 0.663 mmol/g catalyst.UV-Vis results indicated that compared with unmodified TS-1/H2O2 system,the stability and amounts of Ti-OOH active centers were improved after adding H2O2 to the three modified TS-1 catalysts.NH3-TPD results showed that compared with unmodified TS-1/H2O2 system,after adding H2O2 to hydrolyzation of MTES/TS-1 and hydrolyzation of DMDES/TS-1,the amounts of Ti-OOH increased and the amounts of Si-OH decreased obviously.Py-IR results showed that TS-1 modificartion could change the surface acidity of TS-1.The reaction results of 1-hexene epoxidation and butanone ammoximation indicated that the conversion and selectivity of these two reactions were obviously promoted catalyzed by the three modified TS-1 catalysts.The conversion and selectivity of unmodified TS-1 in 1-hexene epoxidation were 59.2%and 64.1%,while the conversion of APTES,MTES and DMDES modified TS-1 were 69.0%,69.0%and 64.7%,the selectivity of them were 68.9%,95.4%and 96.7%.The conversion and selectivity of unmodified TS-1 in butanone ammoximation were 68.0%and 84.3%,while the conversion of APTES,MTES and DMDES modified TS-1 were 71.3%,73.6%and 78.0%,the selectivity of them were 86.5%,97.5%and 99.3%.Combined the results of characterization and analysis with literature,the catalytic oxidation mechanisms of modified TS-1 were discussed.In the system of hydrolyzation of APTES/TS-1,the N atom in-NH2 group can form hydrogen bond with the terminal H atom in Ti-OOH,the Si-OH group can form hydrogen bond with the terminal O atom in Ti-OOH.These two hydrogen bond structures stabilized Ti-OOH active center,improved the quantity of Ti-OOH.And the hydrogen bond of Si-OH and Ti-OOH was more likely to exist.In the systems of hydrolyzation of MTES/TS-1 and hydrolyzation of DMDES/TS-1,the terminal H atom in Si-OH can form hydrogen bond with the terminal O atom in Ti-OOH.This hydrogen-bond interaction improved the stability and quantity of Ti-OOH and made the amounts of Si-OH decrease.Meanwhile,organic groups in silylating reagents also changed the hydrophobicity of catalysts surface.These facters worked together contributing to apparently improvements of conversion and selectivity of 1-hexene epoxidation and butanone ammoximation reactions.更多还原