Research on CO₂ capture and in-situ production of high-quality syngas with calcium-based ores

The Integrated Carbon Capture and Utilization-Reverse Water Gas Shift （ICCU-RWGS） process effectively integrates CO₂ capture with hydrogenation conversion, making it one of the key technological pathways for reducing industrial carbon emissions and advancing the goal of carbon neutrality. At the core of this process is a calcium-based CO₂ sorbent materials, which enable the in-situ conversion of captured CO₂ into syngas through hydrogenation. The syngas quality is typically evaluated using the molar ratio of H₂ to CO_x（M value）. The study aims to efficiently produce syngas with an M value of 2.00 - 2.05 through the proposed process, thereby providing a highly compatible feed gas for downstream processes such as Fischer-Tropsch process and methanol synthesis. Thermodynamic equilibrium analysis and calculations were performed for key operational parameters including temperature, pressure, and calcium-to-hydrogen molar ratio （n（CaCO₃）:n（H₂））. Results indicated that the optimal operating conditions were 700 ℃, 0.1 MPa, and a calcium-to-hydrogen molar ratio of 1:2. Additionally, the presence of H₂O was found to have an adverse impact on the hydrogenation conversion performance. Based on these findings, the screening of calcium-based natural ores was carried out through fixed-bed experimental research. The results demonstrated that dolomite exhibited superior ICCU-RWGS reactivity under reaction conditions of 700 ℃, 0.1 MPa, and a calcium-to-hydrogen molar ratio of 1:2, which aligned well with the thermodynamic predictions. Under these optimal conditions, the cyclic performance of dolomite was further evaluated. The results showed that the M value remained relatively stable over 20 cycles without significant decay, and no evident sintering was observed in the post-reaction dolomite, indicating excellent cyclic stability and structural durability. Overall, based on the ICCU-RWGS process, the study aims to enhance the molar proportion of CO_x in the product gas through systematic optimization of operational parameters, thereby producing high-quality syngas that meets the feedstock requirements for downstream chemical and fuel synthesis.