The following content is copied from this reference ( regarding the use of Cu as catalytic sites of DFMs for ICCU-RWGS.

“Cu as the active metal with and without the promotion of 10% K or Ba was investigated for the ICCC-RWGS process (Hyakutake et al., 2016). Cu/Al2O3 and Cu-Ba/Al2O3 were ruled out as suitable DFMs for the ICCC process, due to their low CO2 uptake capacities, as well as the conversion efficiencies. The modification of K significantly promoted the CO2 uptake capacity and its conversion to CO on Cu (93.4% selectivity) comparing to the unpromoted Cu/Al2O3 as shown in the following figure. The amorphous nature of K under the reaction condition was reported to facilitate the higher dispersion of Cu with a smaller crystallite size. The coverage of Cu by K species was supposed to be crucial to suppress the oxidation of Cu, which was observed on Cu/Al2O3 and Cu-Ba/Al2O3 during the reaction. The captured CO2 in the form of formate was reduced easier to CO on the dispersed metallic Cu in Cu-K/Al2O3. Yet during the capture stage, with the consumption of reactive surface species by CO2, the oxidation of metallic Cu seemed to happen with the release of CO. The switching from capture to conversion stage before the CO2 front reached the end of the catalyst bed was thus suggested to avoid not only CO2 release but also CO formation during the capture stage (Hyakutake et al., 2016).”


Figure results – ICCU-RWGS reactions at 350 °C with 4.4% CO2 in He (in white) vs. 100% H2 (in grey) at 50 mL min−1 at atmospheric pressure over inert SiC (“blank” performed at RT) and over unpromoted and K- and Ba-promoted Cu/Al2O3. (

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