Abstract:

The selectivity of syngas-to-C₂ oxygenates still faces a big challenge. Using density functional theory calculation methods, this study explores the influence of the confined environment of Rh active sites on the reaction performance of syngas conversion to CH _x over four types of RhCu confined catalysts, which further reveals the essential reasons of the confinement effect to regulate the catalytic performance. The results showed that the confined environment of Rh active sites in the RhCu confined catalysts can regulate the activity and selectivity of syngas conversion to generate CH _x . The screened catalyst could perform the highest catalytic activity toward syngas conversion to generate CH _x (x=1—3) monomer. The moderate confinement effect of catalyst made the d-band center of surface atoms far away from the Fermi level, leading to an appropriate electron gain and loss between the transition state of CH₂OH dissociation and RhCu surface, which was conducive to the dissociation of CH₂OH into CH₂ and thus exhibited excellent CH _x formation activity. This study provides theoretical basis for improving the catalytic performance of syngas conversion to C₂ oxygenates by adjusting the confined environment of active site and provides the structural clues for the design of the confined metal single-atom catalysts.

Key words: confined catalyst, confined environment, syngas, CH _x, density functional theory

摘要：

合成气制C₂含氧化合物的选择性目前仍面临巨大挑战。本研究基于密度泛函理论计算方法，探究了4种RhCu限域催化剂中Rh活性位限域环境对合成气转化生成CH _x 反应性能的影响，揭示了RhCu限域催化剂中限域效应调控催化性能的本质。结果表明，RhCu限域催化剂中Rh活性位限域环境能够调控合成气转化生成CH _x 的活性和选择性。筛选获得催化剂具有最高的生成CH _x （x=1~3）单体活性，归因于适中的限域效应使得表层原子d带中心远离费米能级，导致CH₂OH解离过渡态与RhCu表面之间呈现适当的电子转移，利于CH₂OH解离，从而呈现良好的CH _x 生成活性。本研究为通过调变单原子限域环境实现调控合成气转化生成C₂含氧化合物反应的催化性能提供了理论依据，并为单原子限域金属催化剂设计提供了结构线索。

关键词: 限域催化剂, 限域环境, 合成气, 碳氢化合物, 密度泛函理论