N2O在MOF材料上直接催化分解和氧化苯直接制苯酚反应机理的理论研究

Nitrous oxide (N2O) emitted from adipic acid industry is one of the most important ozone-depleting substance. How to effectively eliminate and utilize N2O and to design new efficient catalysts is one of the hot research topics in controlling the current air pollution and in the field of environmental catalysis. Compared to direct catalytic decomposition of N2O, the widely used method in the industry, the oxidation of benzene to phenol achieves the benefits of both environment and economy. In our project, we will study the adsorption properties of N2O and catalytic reactions in the processes of the direct decomposition of N2O and oxidation of benzene to phenol by N2O over M-MOF-74 and M-BTC (M represents transition metal cations) among metal-organic frameworks (MOFs), by means of the density functional theory. Through theoretical calculations, we will reveal the microscopic mechanisms of the direct decomposition and oxidation of benzene to phenol of N2O, explore the effect of the structure and composition of the catalyst on its activity and selectivity, and explain the experimental phenomena. Finally, on the basis of in-depth study on the structural and composition features of the catalyst and the catalytic mechanisms, we aim to elucidate the key factors that affect the performance of the catalysts in N2O elimination and utilization processes, and screen and design the MOFs catalysts which have high reactivity and high selectivity. The present study may provide a reliable theoretical basis for further experimental studies and industrial applications.

己二酸工业排放的N2O已成为人类排放至大气中的首要臭氧层消耗物质。如何有效地消除和利用N2O以及设计新型高效的催化剂，是大气污染治理和环境催化领域研究的热点课题之一。N2O直接催化分解是目前工业上应用最多的方法，而N2O氧化苯直接制苯酚法则实现了环境和经济的双重效益。本项目拟利用密度泛函理论研究N2O在M-MOF-74与M-BTC(M代表过渡金属离子)系列金属有机框架材料 (MOF)上直接催化分解和氧化苯直接制苯酚反应的吸附性质和催化反应过程。通过理论计算给出全面的微观反应机理，探索催化剂的结构和组成对催化反应活性和选择性的影响，正确解释实验现象。在深入研究催化剂结构、组成和催化反应机理的基础上，阐明N2O消除和利用过程中影响催化剂性能的关键因素，筛选和设计高活性和高选择性的MOF催化剂，为实验研究和工业应用提供可靠的理论依据。

N2O的直接催化分解是己二酸工业最常采用的减排方法，而使用N2O氧化苯直接制苯酚法可以实现环境和经济的双重效益。本项目利用密度泛函理论研究了N2O在Fe-MOF74与Fe-BTC材料上直接催化分解和氧化苯直接制苯酚的微观反应机理，取得的研究成果概述如下：.(1) N2O以N端吸附于Fe-BTC上直接催化分解形成NO2是优势反应路径，其次是形成NO路径，最后是生成O2路径。.(2) Fe-BTC上氧化苯直接制苯酚的控速步骤能垒低于NO2反应路径的控速步骤能垒，Fe-BTC是N2O氧化苯直接制苯酚的优良催化剂。.(3) N2O以O端吸附于Fe-MOF74上直接催化分解， 生成NO的反应路径比生成O2的反应路径更具优势。.(4) Fe-MOF74上氧化苯直接制苯酚的控速步骤能垒远低于NO反应路径的控速步骤能垒，Fe-MOF74是N2O氧化苯直接制苯酚的优良催化剂。