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Impacts of char structure evolution and inherent alkali and alkaline earth metallic species catalysis on reactivity during the coal char gasification with CO 2 /H 2 O
Author(s) -
Lv Peng,
Bai Yonghui,
Yang Xuhao,
Gao Meiqi,
Bao Weiren,
Li Fan
Publication year - 2018
Publication title -
international journal of energy research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.808
H-Index - 95
eISSN - 1099-114X
pISSN - 0363-907X
DOI - 10.1002/er.4111
Subject(s) - char , chemistry , coal , alkali metal , reactivity (psychology) , chemical engineering , catalysis , adsorption , alkaline earth metal , specific surface area , carbon fibers , inorganic chemistry , mineralogy , organic chemistry , materials science , composite material , medicine , alternative medicine , pathology , engineering , composite number
Summary In this work, we studied the effects of char structural evolution and alkali and alkaline earth metallic species (AAEMs) catalysis on the reactivity during the char gasification with CO 2 , H 2 O, and their mixture. The gasified chars with different carbon conversion levels were prepared, and their physicochemical structures were characterized via nitrogen adsorption and FT‐Raman techniques. The concentrations of AAEMs in different modes were obtained by the sequential chemical extraction method. The reactivities of the raw and gasified chars were analyzed by the thermogravimetric analysis. The gasification atmospheres had varied effects on the physicochemical structure of coal char. The gasified char obtained in the CO 2 atmosphere had a lower aromatic condensation degree compared with that obtained in the H 2 O atmosphere, irrespective of the temperature. The impact of the atmospheres on the specific surface area of the char varied with the temperature because H 2 O and CO 2 have different routes of development of pore structure with coal char. A large specific surface area facilitates the exposure and dispersion of more AAEMs on the surface of the channel, which is conducive to their contact with the gasification agent to play the catalytic role. Thus, the reactivity of the gasified char is well correlated with its specific surface area at different gasification temperatures. In the absence of AAEMs, the chemical structure of coal char becomes the dominant factor affecting the reactivity.