Effect of different organic compounds on the preparation of CaO-based CO2 sorbents derived from wet mixing combustion synthesis

CaO based sorbents have great potential for commercial use to capture CO2 of power plants. In the demand of producing sorbents with better cyclic performance, CaO-based sorbents derived from different kinds of calcium precursors, containing calcium carbonate (CC-CaO), calcium gluconate monohydrate (CG-CaO), calcium citrate (CCi-CaO) and calcium acetate monohydrate (CA-CaO), were tested cyclically and compared using simultaneous thermal analyzer (STA). And further study was conducted on the sorbents modified with citric acid monohydrate and 50% gluconic acid solution by wet mixing combustion synthesis. The modified sorbents showed better performance and higher pore parameters as well as porous microstructure with more organic acid added. After 20 cycles of carbonation and calcination, the C2CCi8 (CaO: citric acid = 2:8 by mass ratio) and C2G8 (CaO: gluconic acid = 2:8 by mass ratio) sorbent possess CO2 capture capacity of 0.45 g.g(-1) (g CO2 per g sorbents) and 0.52 g.g(-1) respectively. The citric acid was more effective for modification than gluconic acid for extended 50 cycles. Furthermore, good linear relationship between CaO conversion and specific surface area as well as pore volume were determined, of which the specific surface area showed closer correlation with CaO conversion. (C) 2020 The Chemical Industry and Engineering Society of China, and Chemical Industry Press Co., Ltd. All rights reserved.

Automated summary

Through the study of different types of CaO-based sorbents and organically modified sorbents, it was found that the modified sorbents synthesized by wet mixing combustion exhibit better performance and higher pore parameters. Citric acid is more effective than gluconic acid, and there is a good linear relationship between CaO conversion and specific surface area and pore volume.