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Characteristics of as‐prepared biochar derived from catalytic pyrolysis within moderate‐temperature ionic liquid for CO 2 uptake
Author(s) -
Du Yarong,
Fan Zeng,
Guo Tianxiang,
Xu Junpeng,
Han Zhonghe,
Pan Yuanfeng,
Xiao Huining,
Sun Yiming,
Yan Qingqi
Publication year - 2020
Publication title -
the canadian journal of chemical engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.404
H-Index - 67
eISSN - 1939-019X
pISSN - 0008-4034
DOI - 10.1002/cjce.23671
Subject(s) - biochar , adsorption , pyrolysis , ionic liquid , chemistry , catalysis , fourier transform infrared spectroscopy , carbon fibers , chemical engineering , materials science , organic chemistry , composite number , engineering , composite material
A promising biochar as solid adsorbent for CO 2 uptake was prepared by the catalytic pyrolysis of coconut shell in moderate‐temperature ionic liquid (IL). Then, it was characterized by means of SEM, EDS, BPEA, BET, NLDFT, FTIR, and TG‐DSC, and a mechanism interpretation of the porous biochar formation was conducted. In addition, the adsorption characteristics of CO 2 on the as‐prepared biochar, such as adsorption capacity, adsorption potential, isosteric heat, and static selectivity at different adsorption temperatures and pressures, were systematically evaluated. The results indicated that the as‐prepared biochar exhibited an adequate CO 2 adsorption with a capacity of 4.5 mmol/g at 273 K and 100 kPa. Then, a significant number of slit‐like pores were revealed to exist on the as‐prepared biochar with a peak pore size between a range of 0.6 nm‐2 nm. The porous structure formation was ascribed to the release of carbon‐, hydrogen‐, oxygen‐, sulphur‐, and nitrogen‐containing compounds during biochar preparation. Meanwhile, both the adsorption potential and isosteric heat of the CO 2 uptake under the tested conditions decreased with an increase in the adsorption capacity, which ranged from 33 kJ/mol‐21 kJ/mol and 23 kJ/mol‐7 kJ/mol, respectively. Therefore, the isosteric heat could be considered as a piecewise function of adsorption capacity. In addition, the molar ratios of CO 2 over N 2 adsorbed under the tested conditions were above 11 and were accompanied by molar ratio peaks of 26 at 273 K and 19 at 298 K, respectively. Moreover, an interesting phenomenon occurred: the static adsorptive selectivity of CO 2 over N 2 first increased and then decreased and there was an increase in the adsorption pressure at the tested adsorption temperatures.