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Highly selective 1-pentene epoxidation over Ti-MWW with modified microenvironment of Ti active sites
Catalysis Science & Technology ( IF 5 ) Pub Date : 2020-07-22 , DOI: 10.1039/d0cy00478b
Jinpeng Yin 1, 2, 3, 4, 5 , Hao Xu 1, 2, 3, 4, 5 , Bowen Wang 1, 2, 3, 4, 5 , Wenwen Tian 1, 2, 3, 4, 5 , Jianyong Yin 1, 2, 3, 4, 5 , Jingang Jiang 1, 2, 3, 4, 5 , Peng Wu 1, 2, 3, 4, 5
Affiliation  

A titanosilicate/H2O2 catalytic system was applied to process the liquid-phase selective epoxidation of 1-pentene to 1,2-epoxypentane (EP). The effects of titanosilicate topology (MWW, MFI, MSE, MEL, MOR, and *BEA), solvent, H2O/H2O2 ratio, catalyst amount, reaction temperature, pressure, and time on the EP production were investigated systematically. The Ti-MWW/H2O2/acetonitrile system exhibited the highest 1-pentene conversion of 72.9% together with high EP selectivity of 99.9% and H2O2 utilization efficiency of 91.5%. Moreover, it was proved that the Ti active sites located inside the intralayer 10-membered ring sinusoidal channels catalyzed the epoxidation process primarily owing to their supplying more steric fitness for 1-pentene molecules. A piperidine (PI)-assisted structural rearrangement of Ti-MWW was performed to further enhance the catalytic activity, almost doubling the turnover number value. The evolution of the microenvironment of Ti active sites in this structural rearrangement process was carefully investigated, revealing the coordination of N atoms in PI molecules to the Ti atoms. More importantly, we identified that the hexa-coordinated Ti sites with the PI molecules as ligand could significantly accelerate H2O2 activation, the effect of which far exceeded the inhibition effect caused by the electronegativity increase of Ti active sites.

中文翻译:

具有修饰的Ti活性位点微环境的Ti-MWW上的高选择性1-戊烯环氧化

应用钛硅酸盐/ H 2 O 2催化体系处理1-戊烯液相选择性环氧化为1,2-环氧戊烷(EP)。系统地研究了钛硅酸盐拓扑结构(MWW,MFI,MSE,MEL,MOR和* BEA),溶剂,H 2 O / H 2 O 2比例,催化剂用量,反应温度,压力和时间对EP生产的影响。 。Ti-MWW / H 2 O 2 /乙腈体系具有最高的1-戊烯转化率72.9%,以及极高的EP选择性(99.9%)和H 2 O 2利用率为91.5%。此外,已证明位于层内10元环正弦形通道内部的Ti活性位点催化环氧化过程,这主要是由于它们为1-戊烯分子提供了更高的空间适应性。进行了Ti-MWW的哌啶(PI)辅助结构重排,以进一步提高催化活性,使营业额值几乎翻倍。仔细研究了钛活性位点在此结构重排过程中的微环境演变,揭示了PI分子中的N原子与Ti原子的配位。更重要的是,我们发现以PI分子为配体的六配位Ti位点可以显着加速H 2 O 2 活化作用,其作用远远超过了Ti活性位点电负性增加引起的抑制作用。
更新日期:2020-09-05
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