Experimental Investigation On Supported Amine Adsorbents For CO₂ Capture

For post-combustion CO₂ capture, solid amine sorbents have attracted considerable attention due to the lower regeneration energy consumption and corrosion compared with traditional aqueous amine scrubbing technology. This dissertation investigated the supported amine adsorbent from four aspects, that is, the development and test of supported amine sorbents, the regeneration performance and stability, adsorption and regeneration performance in fluidized bed reactor and continuous CO₂ capture demonstration in pilot setup.In the aspect of the development and test of supported amine sorbents, the adsorbent was prepared by wet-impregnation using disordered mesoporous silica gel with various pore diameters and macroporous resin as the support. The effects of pore structure of supports, amine types and loading amount, temperature, CO₂ concentration and water vapor on the adsorption performance were investigated with a thermal gravimetric analyzer（TGA） and fluidized bed reactor. The reaction mechanism between amine and CO₂ with and without steam was analyzed. Based on TGA results, the adsorption model was built and the related chemical equilibrium and kinetic parameters were obtained. The results show that the adsorption capacity increases with the increase of average pore diameter and pore volume of the support while the surface area will exert an effect on the CO 2 uptake when the average pore diameter is above 10 nm. There exists one optimal amine loading amount and adsorption temperature for supported amine sorbents. The p resent of water vapor can promote the adsorption of CO 2 through the change of reaction mechanism between amine and CO₂.The regeneration performance as well as the thermal and chemical stability of supported amines was investigated. Based on the amine evaporation mechanism on the liquid-solid interface, the effect of reaction conditions, amine molecular weight and reactor on the thermal stability was studied. It was found that the support can act as catalyst for CO₂-induced degradation. The bottleneck problem for the application of supported amine sorbents was solved. The results indicated that high amine molecular weight can reduce the amine evaporation rate. The supported amine adsorbent can keep excellent stability during the 100 h test in fluidized bed reactor at 140℃under N2 by entraining some amine vapor into the reactor. The support can accelerate the formation of urea linkages in the order of silica≈13X zeolite>Al2O3>resin for supported amine sorbents. Amine-functionalized ion exchange resin displayed excellent thermal and chemical stability during adsorption and regeneration cycles under pure CO 2.Mathematical models of the CO₂ adsorption and heat transfer process in fluidized bed reactor were developed. A dual fluidized bed reactors system was constructed and operated continuously and stably with the CO 2 capture efficiency of 84.4⁹7%.Based on the research of a gas upward–solids downward countercurrent reactor model and experiment, one pilot setup was designed and operated to evaluate the potential of supported amine sorbents for post-combustion CO₂ capture. The pilot system is composed of one countercurrent downer, two paddle dryers with one used as regenerator and the other as cooler. CO₂ capture efficiencies up to 72⁹5% were reached. At the same time, 80⁹8 vol% CO₂ was obtained in the regenerator. Continuous and stable CO₂ capture was realized in the pilot setup, which could provide reference for practical applications.