The Theoretical Study On The Mechanism Of Cyclohexane Dehydrogenation Activated By Ti₂⁺ At Mixed PES In Gas Phase

The alkane dehydrogenation reaction catalyzed by transition metal ions is widely used in the hydrogen energy. Compared with naked transition metal ions, metal dimer ions have a higher reactivity in the dehydrogenation reaction. For main clues of cyclohexane dehydrogenation catalyzed by Ti₂⁺, we make a series of calculations. We not only discovered 3H₂ same-face dehydrogenation product, but also detected different-face dehydrogenation products [H5D], [H4D2], [H3D3], [H₂D4] in Ti₂⁺ with cyclohexane dehydrogenation reaction. According to the two kinds of different products, the reaction channels were divided into same-face and different-face dehydrogenation two competing reaction channels.In this paper, the mechanism of Ti₂⁺ catalyzed cyclohexane dehydrogenation has been studied at the B3 LYP level of density functional theory?DFT?. The study was based on the reaction potential energy surface, transition state theory, the natural bond orbital theory and referenced the research results of Schwarz et al. Finally, we obtained the stagnation point, optimizing configuration and related parameters which draw the reaction potential energy and analyzed the reaction mechanism in detail. The whole paper consists of four chapters:In the first chapter, we review the concept of quantum chemistry calculation, development history and application, the research progress of transition metal ion cluster activated alkane and the main work of this paper are summarized. In the second chapter, we introduce the theoretical background of this paper research topic and the quantum chemistry calculation methods which is a theoretical foundation for later study.In the third chapter, the same-face dehydrogenation mechanism of cyclohexane catalyzed by Ti₂⁺ is studied, the results show that every molecular dehydrogenation mechanism of the same-face dehydrogenation is similar, and the reaction proceeds in mixed potential energy surface, final product is mixtures of doublet, quartet state, which is exothermic by 13.11kcal/mol for the doublet and 6.87kcal/mol for the quartet states.In the fourth chapter, the different-face dehydrogenation mechanism of cyclohexane catalyzed by Ti₂⁺ is studied, the results show that the sandwich configuration of the different-face dehydrogenation reaction is very important. since the formation of the sandwich configuration is feasible, the different-face dehydrogenation reaction is more favorable than the same-face. the products of different-face dehydrogenation were the mixture of the doublet and the quartet states and was exothermic by 15.52kcal/mol for the doublet and 31.23kcal/mol for the quartet states.