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Comparison of preparation methods for iron–alumina oxygen carrier and its reduction kinetics with hydrogen in chemical looping combustion
Author(s) -
Zhao Haibo,
Mei Daofeng,
Ma Jinchen,
Zheng Chuguang
Publication year - 2014
Publication title -
asia‐pacific journal of chemical engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.348
H-Index - 35
eISSN - 1932-2143
pISSN - 1932-2135
DOI - 10.1002/apj.1791
Subject(s) - chemical looping combustion , hydrogen , chemistry , chemical reaction , chemical kinetics , oxygen , chemical engineering , combustion , nucleation , kinetics , inorganic chemistry , materials science , organic chemistry , physics , quantum mechanics , engineering
Seven preparation methods, namely sol‐gel, co‐precipitation, hydrothermal synthesis, low heating solid‐state reaction, freeze granulation, combustion synthesis, and mechanical mixing, were used to synthesize Fe 2 O 3 /Al 2 O 3 oxygen carrier for chemical looping combustion. A comprehensive physicochemical characterization (i.e. productivity, crushing strength, crystalline characteristics, microstructure, and chemical reactivity with hydrogen) was carried out, and the effects of preparation methods and processes on the oxygen carrier performance were explored. Taking into consideration various physicochemical indices, the sol‐gel method and the freeze granulation method were preferred for oxygen carrier preparation. Following that, a critical chemical reaction in in situ gasification chemical looping combustion, the reduction reaction between oxygen carrier and hydrogen, was clarified in terms of reaction kinetics through the non‐isothermal kinetics analysis and the double extrapolation method. Temperature programmed reduction experiments of the sol‐gel‐derived Fe 2 O 3 /Al 2 O 3 particle and hydrogen were performed using a chemisorption analyzer. The reduction mechanisms and kinetics parameters for the two‐stage reaction (reduced from Fe 2 O 3 to Fe 3 O 4 and then from Fe 3 O 4 to FeAl 2 O 4 ) were determined. In the first stage, the reduction reaction is described by the surface reaction model with an order of 2; on the other hand, the conversion from Fe 3 O 4 to FeAl 2 O 4 is dominated by the nucleation and nuclei growth process. © 2014 Curtin University of Technology and John Wiley & Sons, Ltd.