High temperature H2S removal via CO2-assisted chemical looping over ZrO2-modified Fe2O3

Removal of H2S via hot gas desulfurization demands more advanced and efficient processes to meet the environmental and economic requirements of modern industry. Hereto, we propose a novel process, termed CO2-assisted Chemical Looping Hot Gas Desulfurization (CCLHGD), that involves alternating H2S-induced sulfurization and CO2-enabled regeneration of a core-shell structured ZrO2-modified Fe2O3 oxygen carrier. Such CCLHGD process can be isothermally implemented at 750 °C with Ar-diluted model reactants, i.e., 50 % H2 and 50 ppm H2S for sulfurization and 10 % CO2 for regeneration, wherein all H2S is captured and next released as SO2. Fe2O3 undergoes a stepwise sulfurization (with Fe3O4 and Fe as intermediates) towards iron sulfides, while the latter can be completely regenerated to iron oxides by CO2. The thermally stable ZrO2 in the core-shell structure contributes to resist sintering of the sulfurized iron particles, leading to good regenerability by oxidation with CO2. This work demonstrates an efficient chemical looping scheme for H2S removal, providing new opportunities for hot gas desulfurization.