Highly Cyclic Stability and Absorbent Activity of Carbide Slag Doped with MgO and ZnO for Thermochemical Energy Storage

Caiyun Gao; Yuan Zhang; Dong Li; Mei Li

doi:10.1021/acsomega.2c06061

Highly Cyclic Stability and Absorbent Activity of Carbide Slag Doped with MgO and ZnO for Thermochemical Energy Storage

ACS Omega. 2022 Dec 2;7(49):45443-45454. doi: 10.1021/acsomega.2c06061. eCollection 2022 Dec 13.

Authors

Caiyun Gao^{1

2

3}, Yuan Zhang¹, Dong Li⁴, Mei Li¹

Affiliations

¹ School of Chemistry and Chemical Engineering, North Minzu University, Yinchuan750021, P. R. China.
² Ningxia Key Laboratory of Solar Chemical Conversion Technology, North Minzu University, Yinchuan750021, P. R. China.
³ Key Laboratory for Chemical Engineering and Technology, State Ethnic Affairs Commission, North Minzu University, Yinchuan750021, P. R. China.
⁴ School of Material Science and Engineering, North Minzu University, Yinchuan750021, P. R. China.

Abstract

Carbide slag is a solid waste with a high content of reactive CaO, which can be used as an active material for the chemical absorption of CO₂ and calcium looping. Calcium looping of CaO-based absorbents is one of the most promising methods of thermochemical energy storage. However, the sintering of pores and a reduction in the CO₂ diffusion rates as the carbonization/calcination cyclic reaction progresses have posed challenges to the practical application of CaO-based absorbents. This study proposes a method for alleviating the sintering of the pore structure by improving the activity and cycling stability of such absorbents by doping carbide slag with MgO and ZnO powders. Results showed that the raw material ratio, reaction temperature, and reaction time have a considerable influence on the CO₂ absorption rate. Furthermore, the specific surface area and pore volume of the absorbents increased with increasing ZnO and MgO doping levels in the carbide slag. Thus, the problems of sintering and clogging of pores in CaO-based absorbents were effectively alleviated, and the MgO and ZnO-doped absorbents CMZ85 and CMZ90 maintained 41-42% CO₂ absorption after 10 cycles. These results confirmed that the cyclic stability and absorbent activity improved significantly with the MgO and ZnO doping of carbide slag for the calcium looping process.