Evaluation of multi-functional iron-based carrier from bauxite residual for H₂-rich syngas production via chemical-looping gasification

Solid-fueled chemical-looping gasification (SF-CLG) is a chemical looping technology integrated with gasification for poly-generation, i.e. syngas and power production. This flexible platform could avoid costly air separation unit, providing low cost H₂-rich syngas for the production of fuel chemicals, ammonia, methanol, etc. One key to successful SF-CLG is the development of a multi-functional cyclic solid material that can be treated in large quantities. The solid circulating between the two reactors is the means for oxygen, heat, and catalyst transport. This study demonstrates a cost-effective oxygen carrier (OC) developed from Bauxite residual of alumina industry, containing sufficient active content, multi-supporting materials, and promoter. It is proposed to be a cyclic material to transport oxygen and heat from the air reactor to gasifier to promote gasification, and in its reduced form to catalyze internal syngas reforming. The catalytic functions of this OC for char gasification and syngas reforming were validated. Syngas composition and yield, gasification rate, and OC behavior were investigated at different fuel/OC ratio, and by successive redox cycle in a fluidized bed reactor. The compatibility of new composite materials with the proposed auto-thermal SF-CLG was confirmed based on thermodynamics and the material's physical and chemical properties.