Study on the mechanism and reaction characteristics of metal-supported phosphogypsum as oxygen carrier in a chemical looping gasification application

This study aimed to explore the chemical looping gasification (CLG) reaction characteristics of the metal-supported composite phosphogypsum (PG) oxygen carriers (OCs) and the thermodynamic mechanism. The FactSage 7.1 thermodynamic simulation was used to explore the oxygen release and H 2 S removal mechanisms. The experimental results showed that the syngas yield of CLG with PG-CuFe 2 O 4 was more than that with PG–Fe 2 O 3 20/CuO40 or PG–Fe 2 O 3 30/CuO30 OC at 1023 K when the water vapor content was 0.3. Furthermore, the maximum syngas yield of the CO selectivity was 70.3% and of the CO 2 selectivity was 23.8%. The H 2 /CO value was 0.78, and the highest carbon conversion efficiency was 91.9% in PG-CuFe 2 O 4 at the gasification temperature of 1073 K. The metal-supported PG composite oxygen carrier was proved not only as an oxygen carrier to participate in the preparation of syngas but also as a catalyst to catalyze coal gasification reactions. Furthermore, both the experimental results and FactSage 7.1 thermodynamic analysis revealed that the trapping mechanism of H 2 S by composite OCs was as follows: CuO first lost lattice oxygen as an oxygen carrier to generate Cu 2 O, which, in turn, reacted with H 2 S to generate Cu 2 S. This study provided efficient guidance and reference for OC design in CLG.