Effects of Transition Metal Oxide Catalysts on MEA Solvent Regeneration for the Post-Combustion Carbon Capture Process

Large heat duty for amine regeneration in absorption-based CO₂ capture is one of the major drawbacks of this process. Along with a highly endothermic carbamate breakdown reaction in the stripper, the difficulty of proton transfer from protonated amines to water in the amine regeneration process is also considered a basic reason for high heat duty. Transition metal oxide catalysts can play a vital role in decreasing the required thermal energy for amine regeneration in the stripper by providing Bronsted acids and Lewis acids that would help break down the carbamate by direct attack. MEA saturated with CO₂ at 35 °C, with initial loading of 0.56 mole CO₂/mole amine, was used in this study. The performance of five different transition metal oxide catalysts, V₂O₅, MoO₃, WO₃, TiO₂, and Cr₂O₃, was studied separately to investigate the effects of these catalysts on amine regeneration in the temperature range of 35-86 °C. It has been observed that MoO₃ performance is much better as it regenerated almost double of the MEA solvent than noncatalytic amine regeneration systems, whereas other catalysts also showed considerable differences in amine regeneration in this temperature range. The amine regeneration performance trend was MoO₃ > V₂O₅ > Cr₂O₃ > TiO₂ > WO₃ > blank test. The application of this work would mean that metal oxide catalysts could be used in strippers for a faster CO₂ desorption rate at lower temperature, which would cause a significant reduction of the heat duty.