Ru-based DFMs are mostly used for the ICCC-Met process. The feasibility study of the Ru-based DFMs was first conducted and pioneered by Farrauto and coworkers (Duyar et al., 2015). Ru supported on 𝛾-Al2O3 has been widely reported to be effective for CO2 methanation. After the addition of CaO, the sorbent/catalyst composites produced much more CH4 than the Ru/𝛾-Al2O3. A similar result was also reported by Bermejo-López et al. (Bermejo-López et al., 2019), which showed the dual functionality of the material. Yet CO2 methanation on CaO/𝛾-Al2O3 was not observed, indicating the synergistic effect of the sorbent and catalyst in DFMs. With an increase in the CaO:Ru in the DFMs, a greater extent of CO2 spillover and methanation was observed. The optimum performance was reached for 5%Ru-10%CaO/𝛾-Al2O3 in terms of the CH4 yield per kg of DFM. By changing the active metals as well as the sorbent materials, the performances of DFMs were further investigated by Farrauto et al. (Duyar et al., 2016). The CH4 capacity of the 0.1%Rh-10%CaO/𝛾-Al2O3 was found to be similar to that of 5%Ru-10%CaO/𝛾-Al2O3 (0.4 vs. 0.5 g-mol/kg), possibly due to the higher methanation activity of Rh at lower temperatures. Nonetheless, the Ru-based DFMs showed a faster reaction rate of methanation than Rh-based DFMs, as the methane generation peak was sharp and completed within 25 min on 5%Ru-6.1%Na2O/𝛾Al2O3 compared to ∼ 35 min for 0.5%Ru-6.1%Na2O/𝛾-Al2O3 (ArellanoTreviño et al., 2019). Considering the lower price ($19.9 USD/g for Ru vs. $498.3 USD/g for Rh) (Daily Metal Prices, 2022) and higher stability of Ru, Ru-based DFMs are still promising compared to the Rh-based DFMs (Arellano-Treviño et al., 2019; Duyar et al., 2016).
References
Arellano-Treviño, M.A., He, Z., Libby, M.C., Farrauto, R.J., 2019. Catalysts and adsorbents for CO2 capture and conversion with dual function materials: Limitations of Nicontaining DFMs for flue gas applications. Journal of CO2 Utilization 31, 143–151. doi:10.1016/j.jcou.2019.03.009.
Bermejo-López, A., Pereda-Ayo, B., González-Marcos, J.A., González-Velasco, J.R., 2019a. Mechanism of the CO2 storage and in situ hydrogenation to CH4. Temperature and adsorbent loading effects over Ru-CaO/Al2O3 and Ru-Na2CO3/Al2O3 catalysts. Applied Catalysis B: Environmental 256, 117845. doi:10.1016/j.apcatb.2019.117845.
Daily Metal Prices. https://www.dailymetalprice.com/. (accessed on 2022 .05.20)
Duyar, M.S., Treviño, M.A.A., Farrauto, R.J., 2015. Dual function materials for CO2 capture and conversion using renewable H2. Applied Catalysis B: Environmental 168-169, 370–376. doi:10.1016/j.apcatb.2014.12.025.
Duyar, M.S., Wang, S., Arellano-Treviño, M.A., Farrauto, R.J., 2016. CO2 utilization with a novel dual function material (DFM) for capture and catalytic conversion to synthetic natural gas: An update. Journal of CO2 Utilization 15, 65–71. doi:10.1016/j.jcou.2016.05.003.