Experimental Study On The Solvent Regeneration Of A CO₂-loaded MEA Solution Using Single And Hybrid Solid Acid Catalysts

Since the 19th industrial revolution, people have achieved a rapid development in agricultural and industrial aspects. Thus, the usage of Fossil fuels such as oil, coal, natural gas is gradually rising, the resulting greenhouse gas (CO2) emissions also increased dramatically, which also leads to many environmental problems such as the greenhouse effect, rising temperatures, melting glaciers, rising sea levels. However, CO2 capture, utilization and storage (CCUS) technology is being considered as a promising method to effectively control this problem by capturing CO2 from major point sources such as power plants. In addition, Ethanol amine (MEA) is the most commercially applied chemical absorbent in conventional CO2 post-combustion processes, attributed to its great advantages of fast absorb rate, high absorption capacity, cheap price, good chemical stability and hardly to blister. However, the well-known poor performance of MEA solvent in the regeneration section (the energy requirement for regeneration accounts for nearly 70-80% of the total running cost for a CO2 capture process) is also a reminder to researchers of the necessity to undertake further technology improvement.In this study, ?-Al2O3, H-ZSM-5, H-Y and its hybrid catalysts were selected as the solid acid catalyst to investigate its catalytic performance and catalytic mechanism in MEA solution, and all catalytic desorption experiments were conducted with a batch reactor. In this paper, the experimental temperature was 378 K, the operating pressure was of 1 atm, amine solvent concentration was of 2-7 mol/L, CO2 initial loading was set as 0.5 mol CO2/mol amine, respectively. What's more, several factors such as the catalyst usage, mesoporous specific surface area (MSA) and Br(?)nsted acid sites to Lewis acid sites (B/L) were investigated to inspect its impact on the catalytic performance and catalytic mechanism of the solid acid catalysts. In addition, the results show that catalytic effect for all samples was indeed increased with the increase of the catalyst amount for ?-Al2O3, HZSM-5, H-Y and its hybrid catalysts. What's more, both the mesopore surface area and the ratio of Br(?)nsted acid sites to Lewis acid sites have significant roles to play in the performance of the catalyst in terms of rate of CO2 desorption and heat duty for MEA solvent regeneration. The higher the joint value these two characteristics, the higher the rate of CO2 desorption and the lower the heat duty for MEA solvent regeneration. In addition, another important parameter that was studied was the amine concentration. It can be observed that a faster CO2 desorption rate and a lower heat duty can be obtained with an increase in the concentration of MEA solution.In this study, catalytic effects of the different solid acid catalysts were evaluated both in the gas phase (CO2 desorption rate) and liquid phases (heat duty of CO2 desorption). In addition, on the basis of the distinctive roles of proton donor sites and electron acceptor sites, the conclusion is that the catalytic activity of the catalysts in terms of heat duty decreased in the order:?-Al2O3/H-ZSM-5=2/1>?-Al2O3>H-ZSM-5>H-Y; if operation is conducted in the lean CO2 loading region.On the other hand, if the CO2 capture process is performed in the rich CO2 loading region, the order becomes:H-ZSM-5>?-Al2O3/H-ZSM-5=2/1>?-Al2O3> H-Y.