Cyclic Adsorption Characteristic Of Modified Sorbents For CO₂/SO₂ Capture

It is significant to reduce CO2 emission for preventing global warming.Among technologies of carbon emission reduction, calcination/carbonation reaction is one of the effective methods. For new synthesized sorbents, cyclic reaction characteristic for co-capture CO2/SO2 should be investigated. In terms of dynamics analysis, the separation of rapid and slow reaction step for carbonation process, carbonation kinetics for calcium-based sorbents,and the kinetics of sulfuration and direct sulfuration should be further studied. The above scientific questions are focused and studied. The results can provide theoretical support for co-capture CO2/SO2 with calcium-based sorbents. It has important academic and application vales.Ca O-based sorbents with oxygen vacancy-enriched Ce O2 and Zr O2 as dopants were prepared by the method of wet mixing and the subsequent calcination. Then the cyclic CO2 sorption/desorption performance of the total 24 sorbents was tested with a thermogravimetric analyzer(TGA).The effect of variety and amount of additives, SO2 and other factors on adsorption performance are also investigated.Finally, the kinetics of rapid and slow reaction step for carbonation process and the kinetics of sulfuration and direct sulfuration have be studied. The activation energy of those reaction for sample CL-1/5ZR were obtained.The results show that Ce O2 could accelerate the CO2 sorption rate in the diffusion-controlled regime because that the large quantity of oxygen vacancies in Ce O2 could facilitate the CO2 diffusion through the produced Ca CO3 layer and then react with the uncreated Ca O. The dispersion of Ce O2 on Ca O could also inhibit the agglomeration of Ca O crystal and its sintering under high temperature. It shows that the stability of Ca O in sorption/desorption cycle increase with the rise of the amount of Ce O2 in the sorbents. With a high tammann temperature, the newly produced Ca Zr O3 from zirconia and calcium oxide, could serve as a supporting framework and effectively retrain the sintering. SO2 markedly reduces the CO2-capture capacity for multiple cycles. CO2 capture capacity for CG-1/5CE and CL-1/5ZR decreased as sorption/desorption cycles increased, while the SO2 capture increased with cycles. With combining experimental data and Arrhenius equation, the kinetics of rapid and slow reaction step for carbonation process and the kinetics of sulfuration and direct sulfuration have be studied. The activation energy of those reaction for sample CL-1/5ZR were obtained.In this work, a series of investigations for calcium-based sorbents was taken systematically, such as preparation of synthesis sorbents and cyclic reaction characteristics for CO2 capture and simultaneous CO2/SO2 capture. A new calcium-based sorbent with high reaction capacity was obtained. The activation energy of sulfuration and direct sulfuration for sample CL-1/5ZR was also achieved.