High temperature adsorption of CO₂ on Mg–Al hydrotalcite: Effect of the charge compensating anions and the synthesis pH

• Published in: Catalysis today Vol. 164; no. 1; pp. 198 - 203
• Main Authors: Wang, Qiang, Wu, Zhihuai, Tay, Hui Huang, Chen, Luwei, Liu, Yan, Chang, Jie, Zhong, Ziyi, Luo, Jizhong, Borgna, Armando
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 30.04.2011; Elsevier
• Subjects: adsorbents; adsorption; anions; Catalysis; catalytic activity; Chemistry; Colloidal state and disperse state; Exact sciences and technology; General and physical chemistry; hydrotalcite; Porous materials; surface area; Surface physical chemistry; temperature; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; thermal stability; Warming; Water gas; Doping; Adsorption capacity; capture; High temperature; Anion effect; CO; Thermal stability; Sorption; Heterogeneous catalysis; Pore size; Hydrotalcite; Synthesis; Adsorption; Layered double hydroxide; Morphology; pH; Global warming; Adsorbent; Surface area; Sorption enhanced water gas shift
• ISSN: 0920-5861; 1873-4308
• DOI: 10.1016/j.cattod.2010.10.042

This work reported a detailed investigation on how charge compensating anions and synthesis pH affect the structural properties and CO₂ adsorption capacity of Mg–Al hydrotalcites (HTs). A series of Mg₃Al₁–A (A=CO₃ ²⁻, HCO₃ ⁻, NO₃ ⁻, SO₄ ²⁻, and Cl⁻) HTs were synthesized and tested as high temperature CO₂ adsorbents. It was found that the anions have great effect on the thermal stability and morphology, as well as on the surface area of HTs, consequently influencing the CO₂ adsorption capacity of HT derivatives. Among various HTs, Mg₃Al₁–CO₃ showed the highest CO₂ adsorption capacity of 0.53mmol/g. Next, the influence of synthesis pH on the Mg/Al ratio, BET surface area, pore size, and CO₂ adsorption capacity of Mg₃Al₁–CO₃ was investigated. Mg₃Al₁–CO₃ synthesized at pH=10–12 showed good performance for CO₂ adsorption. By doping Mg₃Al₁–CO₃ (pH=10) with 20wt.% K₂CO₃, the CO₂ adsorption capacity was increased up to 0.85mmol/g.