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Alkali Carbonate Molten Salt Coated Calcium Oxide with Highly Improved Carbon Dioxide Capture Capacity
Author(s) -
Huang Liang,
Zhang Yu,
Gao Wanlin,
Harada Takuya,
Qin Qingqing,
Zheng Qianwen,
Hatton T. Alan,
Wang Qiang
Publication year - 2017
Publication title -
energy technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.91
H-Index - 44
eISSN - 2194-4296
pISSN - 2194-4288
DOI - 10.1002/ente.201600628
Subject(s) - molten salt , calcination , alkali metal , sorbent , melting point , chemical engineering , adsorption , fourier transform infrared spectroscopy , scanning electron microscope , carbon dioxide , inorganic chemistry , carbonate , desorption , salt (chemistry) , chemistry , materials science , organic chemistry , catalysis , engineering , composite material
CO 2 reduction is crucial if the effects of this gas on global warming are to be alleviated. We report for the first time an alkali carbonate molten salt promoted CaO‐based CO 2 sorbent with CO 2 capture performance superior to that of neat CaO. The influences of chemical composition, loading, and melting temperature of the (Li–Na–K) 2 CO 3 molten salts and of the calcination and adsorption temperatures on CO 2 capture were evaluated systematically. The microstructural and morphological evolution of the samples during CO 2 adsorption was studied by X‐ray diffraction, scanning electron microscopy, and Fourier‐transform infrared spectroscopy analyses. The (Li–K) 2 CO 3 molten salt coating was found not only to promote CO 2 uptake but also to facilitate CO 2 desorption from CaO. In particular, at low temperatures of 500 and 600 °C, the CO 2 capture capacity increased significantly from 1.19 and 3.26 mmol g −1 to 6.93 and 10.38 mmol g −1 , respectively. The melting point of the molten salts was also a crucial factor in the improvement of CO 2 uptake. Kinetic studies based on fractal‐like models indicated that the rate coefficients for (Li–K) 2 CO 3 /CaO were approximately 3.3 to 3.8 times larger than those for neat CaO. The coating of alkali carbonate molten salts is believed to prevent the formation of a rigid CaCO 3 layer on the surface of the CaO particles and to provide continuous delivery of CO 3 2− to promote CO 2 capture. During the CO 2 adsorption/desorption cycling tests, (Li–K) 2 CO 3 /CaO resulted in a stable and reversible CO 2 uptake of 6.0–6.3 mmol g −1 , which is much higher than that of neat CaO (2.0 mmol g −1 ).