Increasing Porosity of Molded Calcium‐Based Sorbents by Glucose Templating for Cyclic CO<sub>2</sub> Capture

Xu, Yongqing; Ding, Haoran; Luo, Cong; Zheng, Ying; Li, Xiaoshan; Xu, Yang; Zhang, Zewu; Zhao, Weixian; Zhang, Liqi

doi:10.1002/ceat.201700527

Cited by 22 publications

(9 citation statements)

References 54 publications

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“…CO 2 in flue gas is absorbed by CaO sorbents (transformed into CaCO 3 in a carbonator), and then the CaO is regenerated from CaCO 3 in a calcinator, where a pure CO 2 steam is produced, which can be utilized or geologically isolated. Compared to other absorption technologies, this technique consists of a host of inherent thermodynamic merits such as high CO 2 capture capacity 17 and being an abundant source, 18 which has attracted a large amount of research. However, the major disadvantage of this technique is sintering of CaO occurred during the long-term hightemperature reactions.…”

Section: ■ Introductionmentioning

confidence: 99%

Potential Synergy of Chlorine and Potassium and Sodium Elements in Carbonation Enhancement of CaO-Based Sorbents

Xu¹,

Ding²,

Luo³

et al. 2018

ACS Sustainable Chem. Eng.

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The calcium looping process is well regarded as one of the most prospective technologies for trapping CO2 from flue gas. However, the carbonation conversion of CaO derived from natural Ca precursors decayed drastically during the long-term cycles. Doping has been considered as a promising method to improve the cyclic carbonation performance. However, alkali salt, which derives from abundant natural sustainable resources such as seawater, saline, bittern deposit, and so on, is regarded as a low melting material that can hardly enhance the cyclic carbonation performance of the CaO-based sorbents. In this study, two common alkali salts, sodium and potassium, were doped to investigate the potential enhancing effect of alkali salt on CaO-based sorbents. The cyclic carbonation performance of those sorbents was tested in a simultaneous thermal analyzer (STA), and the enhancing mechanisms were illustrated by scanning electron microscope (SEM), X-ray powder diffraction (XRD), and N2 physical absorption methods. The results illustrated that KCl, NaCl, and K2CO3 boosted the carbonation property of CaO markedly, while KOH, NaOH, and Na2CO3 were detrimental to the sorbents. The synergistic effect of K+, Na+, and Cl– can improve the cyclic carbonation performance of CaO. After 50 cycles, the carbonation conversions of CaO modified by KCl or NaCl were about twice that of unmodified CaO. In general, the KCl and NaCl are promising dopants that can markedly enhance the carbonation property of CaO-based sorbents.

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Section: ■ Introductionmentioning

confidence: 99%

Potential Synergy of Chlorine and Potassium and Sodium Elements in Carbonation Enhancement of CaO-Based Sorbents

Xu¹,

Ding²,

Luo³

et al. 2018

ACS Sustainable Chem. Eng.

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“…Internal compressive stress caused by the rapid release of CO 2 makes particles shrink in the calcination stage. The cracks are easy to form on the surface and inside of CaO materials under the repeated action of chemical and internal compressive forces . Therefore, it is necessary to examine the macrostructural integrity of the CaO honeycomb after different cycles.…”

Section: Resultsmentioning

confidence: 99%

High-Temperature Thermochemical Heat Storage Performance of CaO Honeycombs During CaO/CaCO₃ Cycles

Zhang

et al. 2021

Energy Fuels

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Thermochemical heat storage based on calcium looping is a promising technology for high-temperature solar thermal applications. CaObased materials suffer from severe fragmentation and attrition in multiple heat storage cycles, which can accelerate the elutriation of some fine particles from the reactor. It is necessary to mold CaO-based materials to enhance mechanical strength. In this work, CaO honeycombs prepared by extrusion molding were selected as the molding materials for heat storage. The thermochemical heat storage and mechanical performances of the CaO honeycomb during CaO/CaCO 3 cycles were studied. The effects of carbonation conditions, calcination conditions, and addition amounts of the binder were investigated. As the carbonation pressure increases from 0.1 to 0.2 MPa, the heat storage capacity of the CaO honeycomb is improved significantly, while it decreases rapidly with increasing the carbonation pressure from 0.2 to 1.0 MPa further. The CaO honeycomb carbonated at 0.2 MPa achieves the highest heat storage capacity. The effective conversion and heat storage density of the CaO honeycomb carbonated at 0.2 MPa are 0.45 and 1431 kJ/kg after 25 cycles, respectively, which are both 2.3 times as large as those of the CaO honeycomb carbonated at 0.1 MPa. Polyvinylpyrrolidone (PVP) is an appropriate binder to enhance the heat storage capacity of CaO honeycombs. The CaO honeycomb with 3 wt % PVP exhibits a higher heat storage capacity. Furthermore, the obvious cracks and structural deformation do not appear on the surface of the CaO honeycomb after 20 cycles. The CaO honeycomb carbonated under 0.2 MPa after 20 cycles shows a high crushing strength of 0.663 MPa. This indicates that CaO honeycombs have good thermal shock resistance and mechanical properties. Therefore, CaO honeycombs appear attractive for the calcium looping heat storage.

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“…Sun et al developed the different pore-forming materials, such as cellulose, 37 rice husk, 38 and microalgae, 39 to enhance the CO 2 capture capacity of CaO-based pellets fabricated by the extrusion−spheronization method. Xu et al 40 prepared CaO-based pellets via the extrusion−spheronization method for CO 2 capture and found that these pellets possessed higher mechanical strength compared to limestone. However, the mechanical properties and heat storage capacities of CaO-based pellets prepared by the extrusion−spheronization method during the CaO/CaCO 3 TCHS cycles have not been reported.…”

Section: Introductionmentioning

confidence: 99%

Thermochemical Heat Storage Performance of CaO Pellets Fabricated by Extrusion–Spheronization under Harsh Calcination Conditions

Sun

et al. 2020

Energy Fuels

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To improve the CaO/CaCO 3 thermochemical heat storage capacity and the mechanical property of CaO-based material during the repetitive heat storage cycles, CaO pellets were fabricated by the extrusion−spheronization method. The thermochemical heat storage performance of CaO pellets under pressurized carbonation (3−13 bar) and harsh calcination (950 °C, pure CO 2 ) conditions were studied in a dual fixed-bed reactor. The effects of harsh calcination conditions, carbonation conditions, pellet particle size, and pore-forming agent were determined. CaO pellets carbonated under high pressure exhibit a better heat storage performance than calcined limestone. High carbonation pressure greatly offsets the negative effect of harsh calcination conditions on the heat storage capacity of CaO pellets. When the carbonation pressure is 13 bar, the carbonation conversion and heat storage density of the pellets calcined under harsh conditions reach 0.45 and 1423 kJ/kg after 10 cycles, respectively, which are very close to those calcined under mild conditions (750 °C, pure He). The improvement in heat storage capacity of the pellets becomes slight with increasing the carbonation pressure above 5 bar further. An appropriate carbonation temperature range is 800− 850 °C, and a smaller particle size plays a positive but minor effect on the heat storage capacity of CaO pellets. The optimum heat storage conditions are obtained by the orthogonal experiments. The addition of biomass as a pore-forming agent in the pellets apparently increases the heat storage capacity of CaO pellets during the heat storage cycles. CaO pellets possess a high crushing strength of 4.7 N and high fragmentation resistance. CaO pellets prepared using the extrusion−spheronization method seem promising for CaO/CaCO 3 heat storage.

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Increasing Porosity of Molded Calcium‐Based Sorbents by Glucose Templating for Cyclic CO₂ Capture

Cited by 22 publications

References 54 publications

Potential Synergy of Chlorine and Potassium and Sodium Elements in Carbonation Enhancement of CaO-Based Sorbents

Potential Synergy of Chlorine and Potassium and Sodium Elements in Carbonation Enhancement of CaO-Based Sorbents

High-Temperature Thermochemical Heat Storage Performance of CaO Honeycombs During CaO/CaCO₃ Cycles

Thermochemical Heat Storage Performance of CaO Pellets Fabricated by Extrusion–Spheronization under Harsh Calcination Conditions

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Increasing Porosity of Molded Calcium‐Based Sorbents by Glucose Templating for Cyclic CO2 Capture

Cited by 22 publications

References 54 publications

Potential Synergy of Chlorine and Potassium and Sodium Elements in Carbonation Enhancement of CaO-Based Sorbents

Potential Synergy of Chlorine and Potassium and Sodium Elements in Carbonation Enhancement of CaO-Based Sorbents

High-Temperature Thermochemical Heat Storage Performance of CaO Honeycombs During CaO/CaCO3 Cycles

Thermochemical Heat Storage Performance of CaO Pellets Fabricated by Extrusion–Spheronization under Harsh Calcination Conditions

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Increasing Porosity of Molded Calcium‐Based Sorbents by Glucose Templating for Cyclic CO₂ Capture

High-Temperature Thermochemical Heat Storage Performance of CaO Honeycombs During CaO/CaCO₃ Cycles