Toward Solvent Development for Industrial CO2 Capture by Optimizing the Catalyst-Amine Formulation for Lower Energy Consumption in the Solvent Regeneration Process

The main issue for the development of CO2 capture in industry is its high energy cost. In this work, the regeneration of the chemical solvent 3-(diethylamino)propylamine (DEAPA) with or without catalyst was studied to further reduce the energy consumption. Three different catalysts (SAPO-34, MCM-41, and SO42-/TiO2) were applied into the DEAPA system to enhance the energy efficiency by lowering the heat cost per mole of CO2 released in a CO2 stripping process. The results show that solely DEAPA (without catalyst) can increase the CO2 desorption rate by 37.28%, increase the cyclic capacity by 38.02%, and reduce the heat duty by 14.85% compared to 5 M monoethanolnamine (MEA). In addition, for the catalyst-DEAPA systems, DEAPA-SAPO-34, DEAPA-MCM-41, and DEAPA-SO42-/TiO2 could lower the heat duty by 33.08%, 27.79%, and 22.41%, respectively, relative to 5 M MEA. The SAPO-34 catalyst also shows a better efficiency for increasing the CO2 desorption rate and cyclic capacity compared to the other two catalysts used. Moreover, a possible catalytic mechanism for CO2 desorption from the DEAPA-catalyst system is proposed based on the results from catalyst characterization. Through comparing the parameters of each catalyst, it can be inferred that the mesopore surface area (MSA) and the total acid sites (TAS) are the critical factors for an efficient catalyst. The combination of MAS*TAS could especially act as a key value to evaluate the performance of a catalyst for catalytic CO2 desorption.