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Pore and fractal descriptions of a modified CaO‐based sorbent for sequence SO 2 /CO 2 capture behavior
Author(s) -
Wu Qing,
He Liuqing,
Zhang Lihui,
Duan Feng
Publication year - 2019
Publication title -
greenhouse gases: science and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.45
H-Index - 32
ISSN - 2152-3878
DOI - 10.1002/ghg.1899
Subject(s) - fractal dimension , sulfation , fractal , adsorption , sorbent , diffusion , bet theory , chemistry , specific surface area , porosity , macropore , mineralogy , chemical engineering , materials science , thermodynamics , mathematics , mesoporous material , catalysis , organic chemistry , mathematical analysis , biochemistry , physics , engineering
Sequence SO 2 /CO 2 capture technology will be more attractive as the control on secondary pollution is strengthened and the operating cost is decreased. The sulfation, pore, and fractal characteristics of a spent CaO‐based adsorbent are studied. The spent modified CaO/Ca 12 Al 14 O 33 is used in this study. The effect of cyclic numbers in the calcium‐looping process on sulfation conversion and the pore characteristics of spent adsorbents is investigated. A model between the fractal dimension and the Brunner–Emmet–Teller (BET) specific surface area ( S BET ) of the spent CaO/Ca 12 Al 14 O 33 is established. The sulfation reaction characteristic of spent adsorbents is also interpreted by the fractal mechanism. Results show that the sulfation conversions of spent CaO/Ca 12 Al 14 O 33 are almost 10% higher than those of spent CaO at the same cyclic number. The sulfation reaction rate in the product layer diffusion‐controlled stage is much lower than that in the chemical reaction‐controlled stage. The spent CaO/Ca 12 Al 14 O 33 adsorbents are mainly composed of meso‐ and macropores. The pore size distributions show that there are two peaks in the curves. The surface fractal dimension ( D 1 ) and the pore fractal dimension values of spent adsorbents show a trend that is similar to those of S BET and total pore volume, respectively. The relation between the D 1 values of four different CaO‐based adsorbents and their S BET values is a quadratic function, and a higher D 1 indicates an irregular surface of disordered fractals, which significantly affects the efficiency of the sulfation reaction. © 2019 Society of Chemical Industry and John Wiley & Sons, Ltd.