Dual functional materials (DFMs) including Fe2O3/Al2O3 and CaCO3 were investigated for ICCU-DRM (https://doi.org/10.1021/acs.iecr.9b05783). The authors decoupled the experiments to understand reactions and mechanisms. Single methane reforming at 900 °C was carried out using Fe2O3/Al2O3 and CaCO3, respectively. And the results were compared with ICCU. It is noted that in this work carbonation happened at 600 °C and methane reforming happened at 900 °C in the ICCU process. The results are shown in the following figure.
It is demonstrated that Fe2O3-CH4 reaction mainly produces hydrogen, and has a few reaction steps including metal oxide reduction. The directly reaction between CaCO3 and CH4 produces mainly CO. This might be ascribed to the reaction between CaCO3 and CH4 producing CaO, CO and water, instead of H2 (equations 7 and 8 in the original paper). For the CaCO3-Fe2O3-CH4 reforming process, hydgeon concentration increases significantly, methane conversion also increases, and H2/CO ratio is more stable. A key message from such studies is that the presence of CaCO3 provides CO2 for the reforming process, which limits methane cracking and thus resuling in low coke deposition. In addition, the presence of Fe is essential to obtain a high yield of syngas, as it acts as a catalyst for methane cracking.
