Research progress of hydrogenation of carbon dioxide to ethanol

The carbon dioxide (CO2) hydrogenation to ethanol through chemical conversion is a significant branch of C1 chemistry research. It represents an ideal method for CO2 conversion and has garnered considerable attention for the last few years. Despite remarkable progress in thermal catalytic CO2 hydrogenation to ethanol, several challenges remain that require urgent attention. These include low conversion rates, low selectivity, and the formation of by-products during the hydrogenation process. To address these challenges, this study focuses on conducting a thermodynamic analysis of the CO2 hydrogenation process. It investigates the catalytic performance of both non-noble metals (Co, Cu, and Mo) and noble metals (Rh, Au, Pt, Pd, and Ir) as catalysts in CO2 hydrogenation. The effects of metal active sites on CO2 conversion and ethanol selectivity are thoroughly examined. The study also provides a comprehensive summary of the reaction conditions, including temperature, pressure, feed ratio, space velocity, reactor type, and the presence of water, in CO2 hydrogenation to ethanol. Furthermore, it explains the reaction mechanisms involved in different catalysts. Drawing upon the identified challenges in ethanol synthesis, the study summarizes strategies aimed at improving CO2 conversion and ethanol selectivity. These findings present a valuable theoretical foundation for catalyst design, optimization of reaction conditions, a deeper understanding of reaction mechanisms, and the potential industrial implementation of CO2 hydrogenation to ethanol.