Influence of pressure on ICCU-methanation performance

https://doi.org/10.1016/j.gce.2021.11.009

“Notably, the reaction pressure also affects CO₂ adsorption performance and catalytic activity. Miguel et al. [17] found that by using the mixed bed made of a commercial K-promoted hydrotalcite and Ni-based methanation catalyst, increasing the pressure from 1.34 bar to 2.5 bar, CO₂ adsorption increased slightly from 0.38 mmol g⁻¹ to 0.43 mmol g⁻¹, but CO₂ conversion decreased from 92.5% to 90.8%. Currently, there are feasibility studies of combining direct air capture (DAC) of CO₂ and methanation at intermediate temperature with DFMs [[48], [49], [50]]. Veselovskaya et al. [48] developed the novel process, combining direct CO₂ capture from ambient air using K₂CO₃/Al₂O₃ composite sorbent and CO₂ methanation in the presence of 4% Ru/Al₂O₃ catalyst, which achieves approximately 0.98 mmol g⁻¹ CO₂ capacity and very high values of CO₂ conversion to CH₄ (> 98%). Jeong-Potter et al. [49] further demonstrated the feasibility of employing 0.5% Ru, 6.1% Na₂O/Al₂O₃ DFM for combined DAC of CO₂ followed by methanation at lower temperatures and lower space velocities. Furthermore, cyclic operation with the DFM is also possible in the presence of oxygen and moisture. Kosaka et al. [50] reported significant improvements in iCCC- Methane by increasing the reaction pressure (up to 0.9 MPa), this approach was even able to efficiently capture low concentrated CO₂ (100–400 ppm) for the DAC, and selectively converted it to CH₄.”