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Importance of solvents in preparing highly active Ti-SBA-15 catalysts by grafting method
Microporous and Mesoporous Materials ( IF 5.2 ) Pub Date : 2018-06-26 , DOI: 10.1016/j.micromeso.2018.06.046
Yu-Cheng Lin , Chih-Cheng Chang , Ku-Hsiang Sung , Jyh–Fu Lee , Soofin Cheng

The importance of solvents in preparing Ti-incorporated SBA-15 mesoporous silica (Ti-SBA-15) of highly catalytic activities in epoxidation of bulky alkenes using titanium alkoxides as grafting agents was disclosed. Solvents were found to markedly affect the coordination environment of Ti incorporated on SBA-15. Among the common solvents examined, best dispersion of tetrahedrally coordinated Ti(IV) on silica surface was obtained by grafting in 1-butanol and the second was in 1-hexanol. It is attributed to that the hydrolysis of titanium alkoxides in these alcohols is slower than in other studied solvents, including short-chain alcohols and non-polar hydrocarbons. Detailed studies on the hydrolysis rates of titanium alkoxide in different solvents were examined. In contrast, titanium alkoxides of different alkyl groups as titanium sources were found to have little influences on the structures and catalytic activities of resultant Ti-SBA-15 materials. Ti-SBA-15 of high Ti loading (ca. 4.2% Ti/Si ratio) prepared by grafting with TBOT in 1-butanol was found to have optimal catalytic activities in epoxidation of cycloalkenes, including cyclohexene and dicyclopentadiene, using tert-butylhydroperoxide as the oxidant.



中文翻译:

接枝法制备高活性Ti-SBA-15催化剂中溶剂的重要性

公开了溶剂在使用钛醇盐作为接枝剂制备大烯烃的环氧化中制备具有高催化活性的掺钛的SBA-15中孔二氧化硅(Ti-SBA-15)的重要性。发现溶剂显着影响结合在SBA-15上的Ti的配位环境。在所考察的常见溶剂中,通过在1-丁醇中接枝,第二个在1-己醇中接枝,可以得到四面体配位的Ti(IV)在二氧化硅表面的最佳分散性。这归因于这些醇中钛醇盐的水解要比其他研究的溶剂(包括短链醇和非极性烃)中的水解慢。考察了在不同溶剂中钛醇盐水解速率的详细研究。相比之下,发现不同烷基的钛醇盐作为钛源对所得Ti-SBA-15材料的结构和催化活性影响很小。通过与TBOT接枝1-丁醇制得的高Ti含量(约4.2%Ti / Si比)的Ti-SBA-15被发现在环烯烃(包括环己烯和二环戊二烯)的环氧化中具有最佳的催化活性。叔丁基过氧化氢作为氧化剂。

更新日期:2018-06-26
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