TY - JOUR
T1 - Morphology and composition controllable synthesis of Mg-Al-CO 3 hydrotalcites by tuning the synthesis pH and the CO 2 capture capacity
AU - Wang, Qiang
AU - Tay, Hui Huang
AU - Guo, Zhanhu
AU - Chen, Luwei
AU - Liu, Yan
AU - Chang, Jie
AU - Zhong, Ziyi
AU - Luo, Jizhong
AU - Borgna, Armando
N1 - Funding Information:
This work is financially supported by the Thematic Strategic Research Program (Grant nos. 0921380024 ) from the Agency for Science, Technology and Research (A*STAR) of Singapore .
PY - 2012/1
Y1 - 2012/1
N2 - In order to achieve a controllable synthesis of hydrotalcites (HTs), a systematic investigation on the synthesis of Mg-Al HTs at different pH values was performed. The physical and chemical properties of the synthesized HTs were characterized by X-ray diffraction, scanning electron microscope, thermogravimetric analysis, differential scanning calorimetry, temperature programmed desorption, and BET. The chemical compositions were determined by inductively coupled plasma. The results revealed that the synthesis pH plays a crucial role on the morphology, pore structure and chemical composition of the final products. When the synthesis pH equaled to the isoelectric point (IEP) of Mg-Al HT, "rosette" morphology was formed; while when the pH was higher than the IEP, meso-porous HTs were synthesized. The inter-layered charge compensating anions as well as the Mg/Al ratio also varied with the synthesis pH. Based on our observations, a synthesis mechanism which describes the formation process under various synthesis conditions, was proposed. In addition, we have shown that this mechanism could also be applicable to other synthesis methods. Finally, the CO 2 adsorptions on these synthesized HTs were evaluated. It is clear that the synthesis conditions strongly affected the adsorption capacity. The highest capacity was obtained over the Mg 3Al 1-CO 3 (pH 12) sample, showing a CO 2 capture capacity of 0.83mmol/g when pre-calcined for 1h and 0.58mmol/g when pre-calcined for 6h, respectively.
AB - In order to achieve a controllable synthesis of hydrotalcites (HTs), a systematic investigation on the synthesis of Mg-Al HTs at different pH values was performed. The physical and chemical properties of the synthesized HTs were characterized by X-ray diffraction, scanning electron microscope, thermogravimetric analysis, differential scanning calorimetry, temperature programmed desorption, and BET. The chemical compositions were determined by inductively coupled plasma. The results revealed that the synthesis pH plays a crucial role on the morphology, pore structure and chemical composition of the final products. When the synthesis pH equaled to the isoelectric point (IEP) of Mg-Al HT, "rosette" morphology was formed; while when the pH was higher than the IEP, meso-porous HTs were synthesized. The inter-layered charge compensating anions as well as the Mg/Al ratio also varied with the synthesis pH. Based on our observations, a synthesis mechanism which describes the formation process under various synthesis conditions, was proposed. In addition, we have shown that this mechanism could also be applicable to other synthesis methods. Finally, the CO 2 adsorptions on these synthesized HTs were evaluated. It is clear that the synthesis conditions strongly affected the adsorption capacity. The highest capacity was obtained over the Mg 3Al 1-CO 3 (pH 12) sample, showing a CO 2 capture capacity of 0.83mmol/g when pre-calcined for 1h and 0.58mmol/g when pre-calcined for 6h, respectively.
KW - Effect of pH
KW - Isoelectric point
KW - Layered double hydroxides
KW - Morphology
KW - Synthesis mechanism
KW - γ-AlOOH
UR - http://www.scopus.com/inward/record.url?scp=84855453658&partnerID=8YFLogxK
U2 - 10.1016/j.clay.2011.07.024
DO - 10.1016/j.clay.2011.07.024
M3 - 文章
AN - SCOPUS:84855453658
SN - 0169-1317
VL - 55
SP - 18
EP - 26
JO - Applied Clay Science
JF - Applied Clay Science
ER -