Enhanced CO2 desorption rate for rich amine solution regeneration over hierarchical HZSM-5 catalyst

High energy consumption during the carbon dioxide (CO2) desorption process in amine-based CO2 capture technology is a crucial hindrance to achieving carbon neutrality. HZSM-5 is one of the most widely reported solid acid catalysts used in primary amine regeneration. This work compared a series of HZSM-5 zeolites with different Si/Al ratios in terms of CO2 desorption performance. To further enhance catalytic activity, hierarchical HZSM-5 was synthesized by the dealumination and desilication re-assembly method with different acid and alkali concentrations. The experimental results suggested that desilication by modification in sodium hy-droxide resulted in a significant improvement of mesoporous surface area. The NaOH-0.4 catalyst could improve the amount of desorbed CO2 by 40.3% and decrease the relative heat duty by 28.5%. And the cyclic tests revealed that catalytic activity was well preserved in the recycling process. Moreover, the structure and acidity of modification samples were characterized by X-Ray diffraction (XRD), Fourier transforms infrared (FT-IR), Nitrogen adsorption-desorption experiment, temperature programmed desorption of ammonia (NH3-TPD), Pyridine-adsorption infrared spectroscopy (Py-IR), and scanning electron microscopy (SEM). The characterization results suggested that the synergistic effect of larger mesoporous surface area and total acid sites was important to enhance catalytic CO2 desorption performance. These results showed a new understanding of catalyst design for CO2 capture technology by modifying the structure of the catalyst support.

Automated summary

This study compared the CO2 desorption performance of different Si/Al ratios of HZSM-5 zeolites and successfully synthesized hierarchical HZSM-5 with higher catalytic activity. The results showed that desilication by modification in sodium hydroxide could significantly improve the mesoporous surface area and enhance CO2 desorption capacity. These findings are important for improving catalyst design in CO2 capture technology.