钛硅分子筛TS-1催化烯烃环氧化反应的研究进展

Progress on epoxidation of alkene catalyzed by titanium silicalite-1

摘要:

TS-1催化的烯烃环氧化反应具有条件温和、环境友好、符合绿色化学理念、应用前景广阔等优点。该文首先介绍了不同介质中TS-1催化过氧化氢（H2O2）氧化脂肪烯烃反应的进展，结果表明，在甲醇等质子溶剂中，溶剂可以和Ti— OOH（钛氧活性中心）通过氢键作用形成活性中间体，实现烯烃的环氧化；同时，TS-1的酸中心易引发环氧化物开环、聚合等副反应，适量的碱性添加剂可减少酸性位点，抑制副产物生成，提高环氧化产物的选择性。其次，采用酸改性、碱改性、硅烷化改性或金属盐改性等方法可改善TS-1的催化性能。积碳是TS-1失活的主要原因，高温焙烧、H2O2氧化或热溶剂洗涤可基本恢复TS-1的活性。探索TS-1新的合成与改性方法、以及再生方法与TS-1活性的关系是该领域未来的发展方向。

Abstract:

The epoxidation of alkene catalyzed by titanium silicalite-1 has the advantages of mild conditions, environmental friendliness, conforming to the concept of green chemistry, and broad application prospects. Herein, the research progress of epoxidation of aliphatic alkenes catalyzed by TS-1 with hydrogen peroxide (H2O2) as oxidant in different media was mainly discussed. It was found that an active intermediate was formed from Ti—OOH(Titanium Oxide Active Center) and solvent through hydrogen bonding promoting the epoxidation of alkenes to epoxide when the epoxidation was performed in protonic solvents such as methanol. Meanwhile, the acid center of TS-1 can also promote side reactions such as ring-opening and polymerization of epoxides. Treatment of TS-1 with appropriate amount of alkaline additives can reduce the amounts of acid sites, inhibit the formation of by-products to improve the selectivity of epoxidation products. On the other hand, the catalytic performance of TS-1 for alkene epoxidation can be improved by modification with acid, alkali, silanization or metal salt. In addition, the deactivation of TS-1 is mainly ascribed to carbon deposition in catalytic run. The activity of the catalyst can be recovered largely by calcination in high temperature, oxidation by hydrogen peroxide in situ or washing with hot solvent. They are forecasted that investigations on the novel synthetic and modifying methods, and the relationship between the regeneration protocol and the activity of TS-1 are the developing trends in this field in the future.