SCI和EI收录∣中国化工学会会刊

›› 2014, Vol. 22 ›› Issue (9): 991-999.DOI: 10.1016/j.cjche.2014.06.034

• SEPARATION SCIENCE AND ENGINEERING • Previous Articles     Next Articles

Preparation and Application of the Sol-Gel Combustion Synthesis-Made CaO/CaZrO3 Sorbent for Cyclic CO2 Capture Through the Severe Calcination Condition

Baowen Wang1,2, Xiaoyong Song1, ZonghuaWang3, Chuguang Zheng2   

  1. 1 College of Electric Power, North China University ofWater Resources and Electric Power, Zhengzhou 450011, China;
    2 State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Wuhan 430074, China;
    3 Henan Institute of Metallurgy Corporation, Zhengzhou 450053, China
  • Received:2014-03-13 Revised:2014-05-12 Online:2014-11-04 Published:2014-09-28
  • Supported by:
    Supported by the National Natural Science Foundation of China (51276210, 50906030, 31301586), the Partial Financial Grant of North China University of Water Resources and Electric Power (201012) and the National Basic Research Program of China (2011CB707301).

Preparation and Application of the Sol-Gel Combustion Synthesis-Made CaO/CaZrO3 Sorbent for Cyclic CO2 Capture Through the Severe Calcination Condition

Baowen Wang1,2, Xiaoyong Song1, ZonghuaWang3, Chuguang Zheng2   

  1. 1 College of Electric Power, North China University ofWater Resources and Electric Power, Zhengzhou 450011, China;
    2 State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Wuhan 430074, China;
    3 Henan Institute of Metallurgy Corporation, Zhengzhou 450053, China
  • 通讯作者: Baowen Wang
  • 基金资助:
    Supported by the National Natural Science Foundation of China (51276210, 50906030, 31301586), the Partial Financial Grant of North China University of Water Resources and Electric Power (201012) and the National Basic Research Program of China (2011CB707301).

Abstract: Calciumlooping method has been considered as one of the efficient options to capture CO2 in the combustion flue gas. CaO-based sorbent is the basis for application of calcium looping and should be subjected to the severe calcination condition so as to obtain the concentrated CO2 stream. In this research, CaO/CaZrO3 sorbents were synthesized using the sol-gel combustion synthesis (SGCS) method with urea as fuel. The cyclic reaction performance of the synthesized sorbents was evaluated on a lab-scaled reactor system through calcination at 950℃ in a pure CO2 atmosphere and carbonation at 650℃ in the 15% (by volume) CO2. The mass ratio of CaO to CaZrO3 as 8:2 (designated as Ca8Zr2) was screened as the best option among all the synthesized CaO sorbents for its high CO2 capture capacity and carbonation conversion at the initial cycle. And then a gradual decay in the CO2 capture capacity was observed at the following 10 successive cycles, but hereafter stabilized throughout the later cycles. Furthermore, structural evolution of the carbonated Ca8Zr2 over the looping cycles was investigated. With increasing looping cycles, the pore peak and mean grain size of the carbonated Ca8Zr2 sorbent shifted to the bigger direction but both the surface area (SA) ratio Φ and surface fractal dimension Ds decreased. Finally, morphological transformation of the carbonated Ca8Zr2 was observed. Agglomeration and edge rounding of the newly formed CaCO3 grainswere found as aggravated at the cyclic carbonation stage. As a result, carbonation of Ca8Zr2 with CO2was observed only confined to the external active CaO by the fast formation of the CaCO3 shell outside, which occluded the further carbonation of the unreacted CaO inside. Therefore, enough attention should be paid to the carbonation stage and more effective activation measures should be explored to ensure the unreacted active CaO fully carbonated over the extended looping cycles.

Key words: CO2 capture, Calcium looping cycles, CaO/CaO/CaZrO3 sorbent, Sol-gel combustion synthesis method

摘要: Calciumlooping method has been considered as one of the efficient options to capture CO2 in the combustion flue gas. CaO-based sorbent is the basis for application of calcium looping and should be subjected to the severe calcination condition so as to obtain the concentrated CO2 stream. In this research, CaO/CaZrO3 sorbents were synthesized using the sol-gel combustion synthesis (SGCS) method with urea as fuel. The cyclic reaction performance of the synthesized sorbents was evaluated on a lab-scaled reactor system through calcination at 950℃ in a pure CO2 atmosphere and carbonation at 650℃ in the 15% (by volume) CO2. The mass ratio of CaO to CaZrO3 as 8:2 (designated as Ca8Zr2) was screened as the best option among all the synthesized CaO sorbents for its high CO2 capture capacity and carbonation conversion at the initial cycle. And then a gradual decay in the CO2 capture capacity was observed at the following 10 successive cycles, but hereafter stabilized throughout the later cycles. Furthermore, structural evolution of the carbonated Ca8Zr2 over the looping cycles was investigated. With increasing looping cycles, the pore peak and mean grain size of the carbonated Ca8Zr2 sorbent shifted to the bigger direction but both the surface area (SA) ratio Φ and surface fractal dimension Ds decreased. Finally, morphological transformation of the carbonated Ca8Zr2 was observed. Agglomeration and edge rounding of the newly formed CaCO3 grainswere found as aggravated at the cyclic carbonation stage. As a result, carbonation of Ca8Zr2 with CO2was observed only confined to the external active CaO by the fast formation of the CaCO3 shell outside, which occluded the further carbonation of the unreacted CaO inside. Therefore, enough attention should be paid to the carbonation stage and more effective activation measures should be explored to ensure the unreacted active CaO fully carbonated over the extended looping cycles.

关键词: CO2 capture, Calcium looping cycles, CaO/CaO/CaZrO3 sorbent, Sol-gel combustion synthesis method