Chemical looping gasification and gas formation characteristics of coal-char with iron-based oxygen carrier

Abstract

Clean and low-carbon coal conversion is one of the core research frontiers in the energy field. Chemical looping gasification (CLG), as a promising clean coal utilization technology, oxidized solid fuels using lattice oxygen from oxygen carriers (OCs) without the need for gaseous oxygen. In this study, a series of Fe-Al composite oxygen carriers with different mixing ratios were synthesized via the co-precipitation method. Kinetic analysis and product distribution of coal-char CLG were investigated via thermogravimetric analysis (TGA) and fixed-bed experiments. The results showed that the optimal coal-char gasification performance was achieved with 75% oxygen carrier content at 900 °C final temperature. The random pore model (RPM) accurately described the Fe7Al3 and coal-char CLG in the temperature range of 850 - 950 °C, with a correlation coefficient higher than 0.995. This indicated that the gasification process was controlled by the dynamic evolution of pore structure. According to thermodynamic analysis results, in addition to providing lattice oxygen, iron-based oxygen carriers also reacted with gasification products (H₂ and CO) to generate H₂O and CO₂. Starting from Fe₂O₃ as the initial phase, the iron-based oxygen carriers were reduced in a stepwise manner. This study provided kinetic and thermomechanical foundations for high-efficiency coal-char CLG.

Keywords

Chemical looping gasification / Coal-char / Oxygen carriers / Kinetic analysis / Thermomechanical analysis

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Higher Education Press 2027

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