金/二氧化钛催化剂上丙烯直接环氧化的机理研究。

Mechanistic study into the direct epoxidation of propene over gold/titania catalysts.

作者信息

Nijhuis T Alexander, Visser Tom, Weckhuysen Bert M

机构信息

Department for Inorganic Chemistry and Catalysis, Debye Institute, Utrecht University, Sorbonnelaan 16, 3584 CA Utrecht, The Netherlands.

出版信息

J Phys Chem B. 2005 Oct 20;109(41):19309-19. doi: 10.1021/jp053173p.

DOI:10.1021/jp053173p

PMID:16853494

Abstract

The epoxidation of propene over gold/titania based catalysts was investigated using different techniques. Infrared spectroscopic information showed that one key step in the reaction mechanism is a reaction catalyzed by gold between titania surface groups and propene. In this reaction step, a bidentate propoxy species is formed on titania. This species adsorbs strongly on the catalyst, and it is the same species which is formed when propene oxide adsorbs on titania. Gravimetrical adsorption experiments and catalytic tests show that product adsorption and desorption are important factors determining the catalytic activity and the catalyst stability. By combining the information from different techniques, a kinetic mechanism is proposed.

摘要

采用不同技术研究了丙烯在金/二氧化钛基催化剂上的环氧化反应。红外光谱信息表明，反应机理中的一个关键步骤是金催化二氧化钛表面基团与丙烯之间的反应。在该反应步骤中，二氧化钛上形成了双齿丙氧基物种。该物种强烈吸附在催化剂上，且与环氧丙烷吸附在二氧化钛上时形成的物种相同。重量吸附实验和催化测试表明，产物吸附和解吸是决定催化活性和催化剂稳定性的重要因素。通过结合不同技术的信息，提出了一种动力学机理。