Coke formation and utilization during coke oven gas reforming-CO₂splitting cycles over spherical SrFeO₃pellets for syngas and CO production

Spherical SrFeO3 pellets are used for effective syngas and CO production during coke oven gas reforming (COGR) and CO2 splitting (CS), exhibiting a high CH4 oxidation activity and suppressing reduction by H2 and CO during methane reforming (MR). Above 850 °C, MR produces H2-rich syngas through simultaneous reduction and CH4 decomposition reactions. For sequential CS, CO production is amplified owing to the co-occurrence of CO2 splitting and reverse Boudouard reactions. The redox reaction time is optimized to realize MR-CS cycling with a high redox stability and coke utilization efficiency. From the third MR-CS cycle onward, the reoxidation percentage exceeds 96.4%, consistent with crystal structure evolution. Amorphous carbon is deposited on SrFeO3-δ via the decomposition of CH4 during MR, and the content of this carbon remains constant after the 10th MR-CS cycle because of its high reactivity toward CO2. Over 10 COGR-CS cycles, superior coke utilization due to the occurrence of the reverse Boudouard reaction during COGR results in stable syngas and CO production from the second cycle onward.