原子分散负载金属催化剂催化低碳烷选择脱氢机制的理论研究

Light olefins, such as ethylene and propylene, are important basic raw materials in chemical industry, and the catalytic dehydrogenation of light alkanes has been widely used to produce such olefins. The supported noble metal catalysts, such as the Pt-based catalyst, have superior high activity for the dehydrogenation of alkanes, and have been widely used in industry. However, the existing large Pt aggregates are also quite active for the propylene dehydrogenation and cracking reactions, which result in formation of the carbon deposits and deactivation of the catalyst. Additionally, the rising cost of the noble metal limits its large-scale application. Compared with the supported noble metal catalyst, the atomically dispersed metallic catalyst bears good balance among activity, selectivity, and the maximum optimal use of the noble metal, which shows its great potential for the catalytic production of light olefins. However, such supported atomically dispersed metallic catalysts still face many challenges to maintain high stability, high loadings, and industrial fabrication. Furthermore, the electronic and structural effects on their catalytic performance are less clear and highly require further theoretical and experimental studies. The current project aims to systemically investigate structural features, thermally stabilities, and plausible catalytic mechanisms of new-designed supported atomically dispersed metallic catalysts (M-N/Support：Support=Cu, Cu2O, Al2O3, Cu/Al2O3; M=Pt、Pd、Ir; N=Fe, Co, Ni) toward the selective dehydrogenation of light alkanes (C2~C6) by using first-principles calculations, discuss the effects of interface structure and surface coordination on their catalytic performance, and develop the scaling relations among the adsorption energies, d-band center, and the catalytic activity. The expected results may offer an innovative and efficient way to predict catalytic performance and screen new catalysts with the high activity, high stability, and low costs.

负载型贵金属催化剂是工业上催化烷烃脱氢制备烯烃的重要催化剂，其催化过程易发生深度脱氢和碳碳键裂解等副反应，形成积炭导致催化剂失活。原子分散负载型金属催化剂则可以很好地平衡催化剂的活性、选择性以及最大限度地发挥贵金属的催化效率。但这类催化剂在稳定性、负载量、工业制备等方面还面临巨大挑战，影响其催化性能的电子效应和结构效应目前还不是很清楚。本项目旨在利用第一性原理的方法，系统地研究几类新型原子分散负载型金属催化剂(M-N/Support：Support=Cu, Cu2O, Al2O3、Cu/Al2O3; M=Pt、Pd、Ir; N=Fe, Co, Ni等)的结构、稳定性以及其在低碳烷选择脱氢过程中的催化性能，着重分析活性位界面结构和配位修饰对催化剂性能的影响，探明表界面催化过程的微观机制以及催化活性与d带、吸附能等的标度关系，为催化剂的活性预测和新型原子分散负载金属催化剂的发展提供理论依据。

原子分散负载催化剂在加氢/脱氢、氧还原、析氢、水煤气变化等工业反应中得到了广泛的应用。然而，这类催化剂在稳定性、负载量、工业制备等方面还面临巨大挑战，影响其催化性能的电子效应和结构效应目前还不是很清楚。本项目基于第一性原理的方法，系统性地研究几类原子分散负载型催化剂的结构、稳定性以及其在低碳烷氧化脱氢和分子氧活化过程中的微观机制，评估了活性位界面结构、负载量（活性位点浓度）和配位修饰对其性质及催化性能的影响，为新型原子分散负载催化剂设计与优化等提供理论依据。此外，将红外、拉曼光谱与反应活化能数据相结合，探究红外、拉曼光谱在跟踪反应进程与标定反应路径方面的应用，对深入认识反应机理具有重要意义。