耦合表界面化学反应的分子扩散动力学研究

This project addresses the surface and interface reactions. Towards a deep understanding of the intrinsic relation among reaction rate, molecular diffusion and surface property, we aim to develop a dynamic reaction density functional theory (DFT) by incorporating the classical dynamic DFT with chemical reaction collision theory and quantum DFT. The proposed theory is supposed to provide a new approach towards the investigation of reaction-diffusion coupling in interfacial systems. Similar to reaction molecular dynamics simulation method, reaction dynamics DFT combines two theories individually for the systems at different length scales, and in particular classical dynamic DFT treats the diffusion kinetics of reagent/product molecule species, while chemical reaction collision theory together with quantum DFT deals with chemical reactions. A compromise in completion mechanism exists among the molecular diffusion and reaction, and as a result, the evolution of local density is driven mutually by the gradient of chemical potential and the convert of molecular species. By employing the constructed dynamic reaction DFT with the supplementary of reaction molecular dynamics simulations, we thereafter plan to investigate several important interfacial chemical reactions, and explore the relations among the chemistry of reagent molecules, reaction conditions, interfacial properties and the structural characteristic of involved catalyst etc.. Those relations are revealed from three length scales ranging from molecular scale to interfacial scale and finally to micro-reactor scale, and the particularity and universality of those intrinsic reactions should be further summarized. The success of this project will provide solid support and theoretical guidance for the optimization of some reaction processes and for the design and development of catalyst with improved performance.

本项目针对表界面反应，围绕反应速率、分子扩散和表界面属性等相互关系，通过耦合经典动态密度泛函、分子反应碰撞理论和量子密度泛函，构建多尺度的动态反应密度泛函理论模型，发展表界面体系反应－传递耦合研究新方法。与反应力场分子动力学模拟(Reaction MD) 思想类似，在动态反应密度泛函框架下，反应物和产物的分子扩散、传递采用经典动态密度泛函来处理，而化学反应则结合分子反应碰撞理论和量子密度泛函来研究。两者竞争协调，反应物(产物)组元密度的时空演化由其化学势梯度和化学反应导致的组分转化共同驱动。应用动态反应密度泛函理论兼以反应力场分子动力学模拟为辅助，继而研究化工中若干重要的表界面反应，在分子、表界面、纳微反应器三个层次上揭示反应分子特性、反应条件、表界面属性和催化结构特征对反应效率的影响及调控机制, 归纳出表界面反应机理的一些共性与特性，从而为反应过程优化和催化剂的设计与开发提供理论指导。

纳微表界面体系由于尺度小、限域作用强、反应非均相等原因，呈现出来的“三传一反”规律与体相大相径庭，传统的传递、反应模型不再适用，且传递系数也难以测定。这些挑战反映了纳微表界面理论研究严重滞后，发展表界面强化新技术至今依靠经验摸索。面向这一挑战，本项目聚焦表界面体系，围绕反应速率、分子扩散和表界面作用之间的耦合关系开展研究。通过对限域反应体系中分子扩散驱动“源”进行解构，在化学势梯度驱动的基础上，将反应转化带来的物质局部浓度变化转化为额外的扩散驱动力，进一步将这部分驱动力构建为分子局域密度变量的函数，融入传统上只由化学势梯度驱动的动态密度泛函理论框架，最终成功发展了体现反应能垒贡献的反应-扩散耦合模型(DRxDFT)。应用该模型，研究团队为若干典型的表界面反应过程如双氧水的绿色制备、脱硝、消制氢、界面催化乳化等提供了机理解释，指导了相关技术开发或工艺改进。研究成果发表在ACS Appl. Mater. Interf.、Chem. Eng. J.、AIChE J., Chem. Eng. Sci.、Appl. Energy等SCI/EI期刊上共52篇，申获专利15件，培养博士后、博士和硕士共计15人。在成果的支撑下，项目主持人荣获2018年度长江学者奖励计划青年项目、上海市化学化工庄长恭科学技术进步奖(2018)、中国化工学会侯德榜化工科学技术奖青年奖及中国产学研合作创新奖。学术创新得到同行的认可，项目主持人应邀在三年一度的PPEPPD热力学国际顶尖会议作大会报告。研究成果受到中石油、中石化、索尔维、大塚化学等世界五百强企业的关注，纷纷与项目团队开展合作，持续推进高性能膜材料研制、界面乳化催化、功能乳液、特种添加剂研发等领域的技术攻关和科技成果转化。