CO2 Capture Capacity Of Sorbents Research Articles

Study on the effect of NaBr modification on CaO-based sorbent for CO2 capture and SO2 capture

The calcium looping process has been considered as a promising technology for capturing CO2 from the flue gas, but the decay of CaO-based sorbent, which was caused by the sintering process and the poisoning of SO2, was the major obstacle for its application in industry. In this work, NaBr modification was proposed to enhance the cyclic CO2 capture capacity of the CaO-based sorbents, and the effect of SO2 on the cyclic CO2 capture capacity of the NaBr modified CaO-based sorbents was well studied. The enhancing mechanism of cyclic CO2 capture capacity of the modified CaO-based sorbents was analyzed by X-ray diffraction, field emission scanning electron microscopy, N2 physisorption, and fractal dimensions. The result showed that the SO2 in the flue gas inactivated the CO2 capture activity of the sorbents over the cycles, but the NaBr modification not only enhanced the SO2 capture capacity but also improved the cyclic CO2 capture capacity of the sorbents. The specific surface area and BJH cumulative pore volumes of the sorbents decayed rapidly over the repeated cycles, but the fractal dimensions (D) of the NaBr modified sorbents were still larger than that of unmodified reference sorbent. The “NaBr/CaO” captured 15 grams of CO2 per gram of sorbent over the 50 cycles, which was 2.2 times that of “CaO, AR”. Hence, NaBr modification would be a promising strategy to boost the CO2 capture capacity of the CaO-based sorbent in the calcium looping process that contributes to the carbon neutralization scenarios.

Evaluation of the CO2 gasification of residual char under a regeneration atmosphere via calcium‒based chemical looping gasification

Calcium‒based chemical looping gasification plays a vital role in the utilization of carbon‒based fuels. In this study, the effects of various parameters in the regeneration of CO2 gasification of residual char were studied. Since the CO2 gasification of residual char was an endothermic reaction, the reaction rate increased with temperature. The maximum reaction rate appeared at a CO2 partial pressure of 80%. The carbon conversion rate of residual char increased upon increasing the CO2 capture capacity of sorbent. The CO2 gasification of residual char complied with the shrinking core model instead of the volumetric reaction model, and the municipal solid waste (MSW) char after CO2 gasification was cylindrical shape. The apparent activation energy decreased after adding a sorbent, showing that the CO2 gasification of residual char was improved by adding a sorbent. These results provide an approach to enhance the CO2 utilization in regenerator, outlets and help reduce the oxygen demand and heat losses.

Post-combustion CO2 capture: On the potentiality of amino acid ionic liquid as modifying agent of mesoporous solids

In this paper, mesoporous γ-Al2O3 was impregnated with [Emim][Gly] ionic liquid (IL) at different loadings (5, 9 and 16% wt). The obtained sorbents were tested for CO2 capture under typical conditions of combustion flue-gas at temperatures varying in the range 303–373 K. N2 porosimetric analysis on the samples, coupled with kinetic tests of CO2 adsorption, revealed that a lower pore volume occurring at the highest IL loading ended up in a slower saturation process. The enhancement of CO2 capture capacity of the raw sorbent was monotonic with the IL loading and the best results were achieved at 303 K. The chemisorption nature of the adsorption process for IL-containing sorbents was assessed by means of FT-IR analysis. Finally, preliminary tests of cyclic adsorption/desorption showed that nearly 80% of the original CO2 capture capacity of sorbent was restored by steam desorption at 388 K.

Enhancement of attrition resistance and cyclic CO2 capture of calcium-based sorbent pellets

Calcination/carbonation of calcium-based sorbent is considered one of the most promising technologies to capture CO2. The attrition resistance and CO2 uptake of Ca-based sorbent were of great concern. Efforts were made to enhance the attrition resistance of sorbents primarily by making sorbent pellets with aluminate cements and maintain high CO2 capture capacity of sorbents by adding pore forming agents. Batch experiments were conducted in a fluidized bed to investigate the effect of parameters on sorbent attrition. CO2 capture performance of the pellets was also examined in a calcination/carbonation reactor system. The pore structure characteristics (BET, BJH) were measured as a supplement to the attrition and reaction studies. Results showed that the mechanical property of the pellets with 10wt.% aluminate cement was greatly enhanced. While, CO2 capture capacity of the pellets made with 10wt.% aluminate cement and 5–10wt.% pores forming agent was greatly increased and displayed much slower decay during multiple cycles compared with the original limestone. This was attributed to the large number of mesopores caused by the use of chemical agents and the exposure of inner core of CaO sorbents due to the attrition, which are in favor of CO2 capture. The pore structure showed that the BET surface area and BJH pore volume were expanded by adding pore forming agents, which benefits CO2 uptake of the sorbents during the cycling.