Hydrogen-enriched syngas production by lignite chemical looping gasification with composite oxygen carriers of phosphogypsum and steel slag

Abstract

Chemical looping gasification (CLG) is a clean and efficient carbon energy conversion pathway using oxygen carriers (OCs). Industrial solid wastes, such as phosphogypsum (PG) and steel slag (SS), used as practical resources to prepare OCs, have been proven to be a promising strategy. Single industrial waste has been used for OCs preparation; however, two or more types of waste have not been used for OCs preparation. In this work, PG and SS were used to prepare OCs for hydrogen-enriched syngas production through CLG technology. The prepared OCs by PG and SS increase the solid waste utilization rate and significantly reduce preparation costs. Further, the reaction process and the effects of reaction conditions were studied based on the FactSage calculation and verified in fixed bed experiments. The results show that SS effectively improved PG-OCs performance. Moreover, the most economic optimal conditions for producing hydrogen-enriched syngas (found to be 72.51%) were determined as a reaction temperature of around 1023 K, lignite/OCs mass ratio of 1, 50 wt% - 67 wt% of SS/OCs mass ratio, and water vapor/OCs mass ratio of 0.6. In conclusion, SS-PG OCs are the new era for hydrogen-enriched syngas production in CLG.