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Coke formation on DFMs for ICCU-DRM

Carbon can be produced at the stage of CO2 utilisation. In particular, ICCU-DRM produces a significant amount of carbon on the surface of DFMs, as coke formation is a key challenge for conventional DRM. The formation of coke not only affects the reactivity of DFMs, but also causes new issues. For example, if flue gas is used as the CO2 source, the reaction between CO2 and deposited carbon can generate CO at the carbon capture stage. New pollutant CO in flue gas will cause environmental issues. However, if syngas or biogas is used as the CO2 source, the production of CO at the carbon capture stage will not be an issue. A separate stage of DFMs treatment under steam could be added to remove the deposited carbon. Alternatively, the design of DFMs should be advanced to reduce carbon deposition.

The following content of ICCU-DRM related to coke deposition is from this reference (https://doi.org/10.1016/j.ccst.2022.100052).

“During the DRM process, carbon deposition is widely reported on the Ni-based DFMs, especially in the later stage of the reforming reaction with the consumption of CO2 (Gu et al., 2022Hu et al., 2021bKim et al., 2018). Nonetheless, the deposited carbon can be removed in the subsequent CO2 capture process via the reverse Boudouard reaction (Eq. 11). For example, over the 10Ni-CaO DFM, carbon deposition due to CH4 decomposition (Eq. 7) caused a significant decrease in the surface exposure of Ni from 262 to 10 μmol/g. However, after the capture stage, the deposited carbon was removed by the reverse Boudouard reaction, and the exposure of Ni was restored to 255 μmol/g (Kim et al., 2018). Moreover, it was also reported that the modification of CeO2 was capable of suppressing the accumulation of inactive carbon on Ni due to the high mobility of lattice oxygen in CeO2 (Hu et al., 2021b). Furthermore, other methods, such as manipulating the Ni particle sizes and using bimetallic Ni-based catalysts, were suggested to alleviate the carbon deposition (Tian et al., 2019).

(11)CO2 + C ↔ 2CO

1-s2.0-S0926337320311516-gr9_lrg

CO2 and deposited carbon reaction during ICCU-DRM (https://doi.org/10.1016/j.apcatb.2020.119734)

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