(25a) Computational Insight Into Design of Ethanol Synthesis Catalysts
The direct conversion of synthesis gas to higher alcohols is an attractive chemical process due to the high value of alcohols as fuel blends and the numerous possibilities for production of synthesis gas. Despite years of research the industrial viability of such a process is severely limited due to lack of catalysts with sufficient activity and selectivity. This talk contributes to the understanding of why it has been difficult to find transition-metal higher alcohol catalysts, and points to possible strategies for discovering new active and selective catalysts. The work is based on extensive density functional theory (DFT) calculations to determine the energetics of ethanol formation on a series of metal (211) surfaces. The energetic information is used to construct a mean-field micro-kinetic model for the formation of ethanol via the CO insertion mechanism. The kinetic model is used along with a descriptor-based analysis to gain insight into the fundamental factors determining activity and selectivity on transition-metal surfaces. The results are consistent with experimental observations and give quantitative insight into the balance between molecular and dissociative adsorption of CO which is required to selectively produce higher alcohols.