Heterogeneous Catalytic Systems for Carbon Dioxide Hydrogenation to Value-Added Chemicals

Abstract

Utilizing renewable energy to hydrogenate carbon dioxide into fuels eliminates massive CO₂ emissions from the atmosphere and diminishes our need for using fossil fuels. This review presents the most recent developments for designing heterogeneous catalysts for the hydrogenation of CO₂ to formate, methanol, and C₂₊ hydrocarbons. Thermodynamic challenges and mechanistic insights are discussed, providing a strong foundation to propose a suitable catalyst. The main body of this review focuses on nanostructured catalysts for constructing efficient heterogeneous systems. The most important factors affecting catalytic performance are highlighted, including active metals, supports and promoters that can potentially be used. The summary of the results and the outlook are presented in the final section. During the past few decades, heterogeneous CO₂ hydrogenation has gained much attention and made tremendous progress. Thus, many highly efficient catalysts have been studied to discover their active sites and provide mechanistic insights. This paper summarizes recent advances in CO₂ hydrogenation and its conversion into various hydrocarbons such as formate, methanol, and C₂₊ products. As for formate production, Au and Ru nanocatalysts show superior activity. However, considering the catalyst cost, Cu-based catalysts have an excellent prospect for methanol production, among other catalysts. Ultra-small nanoparticles and nanoclusters appear promising to provide highly active cost-effective catalysts. A growing number of researchers are investigating the possibility of directly synthesizing C₂₊ products through CO₂ hydrogenation. The major challenge in producing heavy hydrocarbons is breaking the ASF limitations, which have been achieved over bifunctional catalysts using zeolites. Using suitable support and promoter can lead to a superior activity, ascribed to structural, electronic, and chemical promotional effects.

Keywords: C2+ hydrocarbons; CO2 hydrogenation; formate; heterogeneous catalysis; methanol.