THERMODYNAMIC EVALUATION OF METHANOL SYNTHESIS VIA CARBON DIOXIDE HYDROGENATION AND LIQUID-VAPOR SEPARATION

Abstract

Methanol is an input widely used in the chemical industry as a solvent and component for various products, but it faces challenges in its conventional production, including CO2 hydrogenation, methane oxidation, or thermal gasification of agricultural biomass, due to the need for expensive catalysts. This work aims to evaluate the thermodynamic parameters of methanol synthesis from CO2 hydrogenation through computer simulation. In the DWSIM simulator, the parameters or variables temperature, pressure, conversion and product flow were evaluated for equilibrium conditions. The results expressed the duality of the reaction system: (1) the methanol synthesis reaction is exothermic and dominates the conversion of CO₂ at lower temperatures; (2) the Reverse Water-Gas Shift (RWGS) reaction is endothermic and prevails at higher temperatures and the increase in pressure favors the conversion of CO₂ in an approximately linear manner. The synthesis of methanol to optimize the use of carbon dioxide has aroused interest in many industries, including the availability of renewable hydrogen. Thermodynamic evaluation is therefore essential to understand the behavior of the reaction system of interest. In the subsequent liquid-vapor separation part of the aqueous system, the UNIQUAC model approach was applied accurately with only two binary interaction parameters. The liquid-vapor behavior predicted under the conditions of interest, approximately 230 ºC and 50 bar, proved to be unsuitable for methanol purification despite not showing azeotropy. Finally, the thermodynamic analysis of the process made it possible to describe the dependence of the operating conditions on methanol synthesis.