ENHANCED REGENERATION OF CO2-LOADED AMINE SOLVENT OVER NH4HF2 AND Ce2(SO4)3.8H2O MODIFIED HZSM-5 CATALYST
Increased levels of carbon dioxide in the atmosphere are widely accepted as the main cause of greenhouse effect and global warming. Various technologies including CO2 capture have been introduced. For CO2 capture, amine absorption is the most used technique in the industry, but it requires high energy consumption during the solvent regeneration process through CO2 stripping. HZSM-5 catalyst is one of the most common solid acid catalysts employed to enhance the regeneration process. However, such catalysts are characterized with micropores and narrow pore structures along with limited mass transfer rate.
Funded by Mitacs Globalink Research Award, this work sought to enhance the efficiency of the regeneration process through improved catalyst design, specifically using hierarchical HZSM-5 catalysts synthesized via a dealumination re-assembly method with varying acid concentrations. The desorption experiments were conducted at a temperature of 90°C with an aqueous MEA solvent concentration of 30wt.%.
The experimental results show that HZSM-5 catalysts modified with ammonium bifluoride acid (in particular 0.6M) demonstrate high efficiency in enhancing the regeneration process by significantly increasing the CO2 desorption rate and cyclic capacity. Interestingly, relative to blank (uncatalyzed) and untreated-HZSM-5 systems, the optimal acid-modified HZSM-5 catalyst, HZ-2, increased the CO2 desorption rate by about 70% and 49% respectively. Additionally, HZ-2 catalyst reduced the heat of desorption further by approximately 32% and 40% when compared against untreated HZSM-5 catalyst system and blank MEA solvent system. These findings present a novel approach to designing catalysts for CO2 capture technology through structural modification of the catalyst support.