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Morphological Changes of Pure Micro‐ and Nano‐Sized CaCO 3 during a Calcium Looping Cycle for CO 2 Capture
Author(s) -
Luo C.,
Shen Q.,
Ding N.,
Feng Z.,
Zheng Y.,
Zheng C.
Publication year - 2012
Publication title -
chemical engineering and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.403
H-Index - 81
eISSN - 1521-4125
pISSN - 0930-7516
DOI - 10.1002/ceat.201000299
Subject(s) - carbonation , sorbent , crystallite , calcium looping , chemical engineering , sintering , nano , materials science , calcium carbonate , mineralogy , carbonatation , chemistry , composite material , metallurgy , adsorption , organic chemistry , engineering
Abstract Cyclic CO 2 capture using CaO‐based sorbents derived from commercial pure micro‐sized CaCO 3 and nano‐sized CaCO 3 was investigated, focusing on the different characteristics of carbonation conversions, carbonation rates, surface areas, pore volumes, morphological changes, and microstrains of two sorbents during high‐temperature reactions. The results indicated that the CaO‐based sorbent derived from nano‐sized CaCO 3 (NC‐CaO) provided higher carbonation conversions and carbonation rates than the CaO‐based sorbent derived from micro‐sized CaCO 3 (MC‐CaO) in the cyclic CO 2 capture reactions. Furthermore, NC‐CaO retained its fast carbonation rate at the beginning of each cycle for several tens of seconds. In contrast, the carbonation rate of MC‐CaO diminished with an increase in the cycle number. Unfortunately, NC‐CaO sintered more easily. Its grains, which were composed of numerous spherical nanocrystallites, suffered from dramatic morphological changes during high‐temperature reactions. A mechanism of grain boundary migration was employed to explain the sintering of CaO‐based sorbent. The smaller crystallites were more susceptible to be merged by the bigger crystallites during high‐temperature reactions.