本文選題：鈦摻雜 + 乙基橋聯(lián)��； 參考：《華東理工大學》2017年碩士論文

【摘要】：鈦摻雜有機基團橋聯(lián)型介孔分子篩(Ti-PMO)是一類新型的介孔材料,不僅具有常規(guī)無機介孔分子篩的均一孔徑、高比表面積和孔容等優(yōu)點,而且其橋聯(lián)的有機基團均勻分布在介孔骨架中,能夠保護Si-O-Si鍵不被水解,因而具有出色的水熱穩(wěn)定性和疏水性。因此,Ti-PMO在一些大分子液相氧化反應(yīng)中具有潛在的應(yīng)用前景。盡管普遍認為含鈦分子篩中孤立的骨架四配位鈦是一些選擇性氧化反應(yīng)的活性中心,但活性位的確切性質(zhì)仍存在爭議,尤其是有越來越多的文獻報道骨架中的四配位鈦物種并不是唯一的活性中心。本文首先以商業(yè)TS-1為催化劑優(yōu)化環(huán)己酮氨肟化反應(yīng)工藝條件,為后續(xù)合成的介孔分子篩的考評提供依據(jù)。為了使反應(yīng)過程中環(huán)己酮、H_2O_2和NH3三者的濃度較好匹配,并保持反應(yīng)在堿性條件下進行,氨水采用間歇等份的進料方式。優(yōu)化后,環(huán)己酮、氨水和雙氧水的摩爾比為1:2.5:1.25。其次以TiCl3為鈦源合成了具有良好的水熱穩(wěn)定性的鈦摻雜乙基橋聯(lián)的有機雜化介孔(Ti-EPMO)分子篩,系統(tǒng)考察了無機鹽添加量、晶化溫度、溶液酸度、硅源預水解時間和硅鈦比等合成工藝條件對分子篩的物化性質(zhì)的影響,并以環(huán)己酮氨肟化反應(yīng)作為探針反應(yīng)考評了其催化性能。結(jié)果表明無機鹽是Ti-EPMO形成二維六方介孔結(jié)構(gòu)的重要因素,而溫度、酸度和硅鈦比對分子篩中鈦含量和鈦配位形式的影響較大,當無機鹽添加量為Si摩爾量的4倍、晶化溫度為60℃、溶液酸度為0.016 mol/L、硅源預水解時間為6 h、硅鈦比為40時合成的Ti-EPMO在環(huán)己酮氨肟化反應(yīng)中具有最優(yōu)的催化性能。最后,分別以BTEE和TEOS為硅源合成了鈦摻雜乙基橋聯(lián)的有機無機雜化介孔(Ti-HPMO)分子篩,并以環(huán)己酮氨肟化作為探針反應(yīng)考察了其催化氧化性能。結(jié)果表明骨架內(nèi)有乙基橋聯(lián)(-C-Si-O-)的Ti-HPMO具有規(guī)整的六方介孔孔道和較高的疏水性,較以TEOS為硅源得到的無機介孔分子篩在反應(yīng)中呈現(xiàn)較高的肟選擇性。進一步研究了模板劑移除和酸處理對Ti-HPMO中鈦物種存在形式的影響并與其環(huán)己酮氨肟化的催化性能相關(guān)聯(lián),認為有機雜化的介孔分子篩中的四配位鈦和非骨架的六配位鈦均為環(huán)己酮氨肟化反應(yīng)活性中心。
[Abstract]:Titanium doped organic group bridged mesoporous molecular sieves Ti-PMOs are a new kind of mesoporous materials, which not only have the advantages of homogeneous pore size, high specific surface area and pore volume of conventional inorganic mesoporous molecular sieves. Moreover, the organic groups are uniformly distributed in the mesoporous framework, which can protect the Si-O-Si bond from hydrolysis, so it has excellent hydrothermal stability and hydrophobicity. Therefore, Ti-PMO has a potential application prospect in some macromolecular liquid phase oxidation reactions. Although it is generally believed that the isolated framework tetracoordination titanium in titanium-containing molecular sieves is the active center of some selective oxidation reactions, the exact properties of the active sites remain controversial. In particular, there are more and more reports that tetra-coordinated titanium species in the skeleton are not the only active centers. In this paper, commercial TS-1 was used as catalyst to optimize the reaction conditions of cyclohexanone ammoximation, which provided the basis for the evaluation of mesoporous molecular sieves. In order to match the concentration of H _ S _ 2O _ 2 and NH3 in the reaction process and keep the reaction in alkaline condition, ammonia water was fed in batch and equal proportion. After optimization, the molar ratio of cyclohexanone, ammonia and hydrogen peroxide is 1: 2.5: 1. 25. Secondly, Ti-EPMO-organic hybrid mesoporous molecular sieve with good hydrothermal stability was synthesized by using TiCl3 as titanium source. The addition of inorganic salts, crystallization temperature and acidity of the solution were systematically investigated. The effects of the pre-hydrolysis time of silicon source and the ratio of silicon to titanium on the physical and chemical properties of molecular sieve were studied. The catalytic properties of the molecular sieve were evaluated with cyclohexanone ammoximation as the probe reaction. The results show that inorganic salt is an important factor in the formation of two-dimensional hexagonal mesoporous structure of Ti-EPMO, and the effects of temperature, acidity and ratio of Si to Ti on the content of titanium and the coordination form of titanium in molecular sieve are greater, when the amount of inorganic salt added is 4 times of the molar amount of Si. When the crystallization temperature is 60 鈩，

本文編號：1874207