Coke formation and utilization during coke oven gas reforming–CO2 splitting cycles over spherical SrFeO3 pellets for syngas and CO production

Abstract

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 SrFeO_3−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.