Thermodynamic Analysis of CO₂ Hydrogenation to Higher Alcohols (C_2–4OH): Effects of Isomers and Methane

Abstract

Synthesis of higher alcohols (C_2-4OH) by CO₂ hydrogenation presents a promising way to convert CO₂ into value-added fuels and chemicals. Understanding the thermodynamics of CO₂ hydrogenation is of great importance to tailor the reaction network toward synthesis of higher alcohols; however, the thermodynamic effects of various alcohol isomers and methane in the reaction system have not yet been fully understood. Thus, we used Aspen Plus to perform thermodynamic analysis of CO₂ hydrogenation to higher alcohols, studying the effects of alcohol isomers and methane. Thermodynamically, methane is the most favorable product in a reaction system containing CO, CO₂, and H₂, as well as C_1-4 alkanes, alkenes, and alcohols. The thermodynamic favorability of alcohol isomers varies significantly. The presence of methane generally deteriorates the formation of higher alcohols. However, low temperature, high pressure, high H₂/CO₂ ratio, and formation of alcohols with a longer carbon chain can reduce the effects of methane. Our current study, therefore, provides new insights for enhancing the synthesis of higher alcohols by CO₂ hydrogenation.