Analysis of hydrogen-rich syngas generation in chemical looping gasification of lignite: Application of carbide slag as the oxygen carrier, hydrogen carrier, and in-situ carbon capture agent

Chemical looping gasification (CLG) has become a popular method for producing hydrogen-rich syngas due to its environment-friendliness. Recently, a method of using industrial solid waste carbide slag as an oxygen carrier, hydrogen carrier, and in-situ carbon capture agent in the CLG process has been proposed. However, the actual experiment was affected by heat and mass transfer, and the detailed reaction pathway of the carbide slag was not fully understood. In the present study, the process of the CLG process for producing hydrogen-rich syngas with lignite and carbide slag was analyzed using tube furnace experiments, FactSage calculations, and joint charac-teristic experiment of carbide slag. The result showed that to achieve a gas phase product with a hydrogen concentration exceeding 90 vol% (with dry N2 excluded), a molar ratio of lignite to carbide slag of greater than 1:5 and a reaction temperature of 923 K should be maintained. In terms of the reaction pathway of carbide slag in the CLG process, it was revealed that calcium hydroxide, the primary component of carbide slag, directly participated in the reaction at temperatures of less than 773 K. Overall, this work provides a novel idea for the preparation of hydrogen-rich syngas during CLG process.

Automated summary

Chemical looping gasification (CLG) using industrial solid waste carbide slag as an oxygen carrier, hydrogen carrier, and carbon capture agent is proposed as a method for producing hydrogen-rich syngas. Tube furnace experiments, FactSage calculations, and joint characteristic experiments were conducted to analyze the CLG process using lignite and carbide slag. The results show that a lignite to carbide slag molar ratio greater than 1:5 and a reaction temperature of 923 K are required to achieve a gas phase product with a hydrogen concentration exceeding 90 vol%. The study also reveals the reaction pathway of the carbide slag in the CLG process, indicating that calcium hydroxide, the primary component of the slag, directly participates in the reaction at temperatures below 773 K. This work provides a novel idea for the preparation of hydrogen-rich syngas during CLG process.