Study on the 3D-printed monolithic ZSM-5 catalyst to enhance CO2 desorption from amine solutions

CO2 desorption catalyzed by solid acid is one of the effective ways to reduce the energy consumption in the post-combustion. In this study, 3D printing technology was employed to construct a monolithic catalyst based on ZSM-5 with a direct ink writing (DIW) method. The performance of CO2 desorption from amine solution was studied in a continuous bubbling reactor at mild temperatures (3-TPD, BET, and N2 isothermal adsorption–desorption to single out the optimal preparation method. A computer vision method was established to investigate the formation of CO2 bubbles on the surface of the 3D-printed catalyst and their evolution in the liquid bulk. The results show that the ink for 3D-printed catalysts based on ZSM-5 with a low Si/Al ratio provided more surface mesopores and active sites, leading to an increase of 46.0 %–121.6 % in the maximum CO2 desorption rate and 16.3 %–36.0 % in the CO2 desorption capacity, compared to the blank amine solution. A lower sintering temperature is conducive to retaining the active sites on the catalyst surface, thereby effectively enhancing the kinetics of CO2 desorption. The optimal Si/Al ratio and sintering temperature for the ink of 3D-printed catalysts were 25 and 550 °C, respectively, which can reduce the CO2 desorption energy by 26.5 %. And the reduction of CO2 desorption amount for various ZSM-5 based inks did not exceed 6.0 % after multiple cyclic testing. The 3D-printed ZSM-5 monolithic catalysts increased the total CO2 amount by 54.8 % at most compared to blank absorbents, because the grille configurations provided more specific surface area to promote the deprotonation of MEAH+ and the decomposition of MEACOO-. Meanwhile, the larger pore structure of the 3D-printed channels facilitated the diffusion of desorbed CO2 into the liquid phase. Compared to the Square channel, the Diamond channel with a lower surface Gibbs free energy enhanced the precipitation of CO2 on the catalyst surface and the coalescence of CO2 bubbles in the liquid phase, accelerating the desorption of CO2 from amine solution at mild temperature. This study provides an effective approach for developing low-cost, high-performance catalysts by 3D-printing technology for CO2 desorption from amine solutions. © 2024 Elsevier B.V.