Very low Ru loadings boosting performance of Ni-based dual-function materials during the integrated CO2 capture and methanation process

• Published in: Journal of energy chemistry 2025-03, Vol.102, p.309-328
• Main Authors: Tsiotsias, Anastasios I., Harkou, Eleana, Charisiou, Nikolaos D., Sebastian, Victor, Naikwadi, Dhanaji R., van der Linden, Bart, Bansode, Atul, Stoian, Dragos, Manos, George, Constantinou, Achilleas, Goula, Maria A.
• Format: Article
• Language: English
• Subjects: Bimetallic materials; CFD modelling; Dual-function materials; in-situ DRIFTS; Integrated CO2 capture and methanation; Nickel-ruthenium; Reducibility
• ISSN: 2095-4956
• DOI: 10.1016/j.jechem.2024.11.001

The addition of very low Ru amounts in Ni/Na2O/Al2O3 dual-function materials drastically increases the material reducibility, the CH4 yield, and the CH4 production kinetics during the integrated CO2 capture and methanation process. [Display omitted] Herein, the effect of the Ru:Ni bimetallic composition in dual-function materials (DFMs) for the integrated CO2 capture and methanation process (ICCU-Methanation) is systematically evaluated and combined with a thorough material characterization, as well as a mechanistic (in-situ diffuse reflectance infrared fourier-transform spectroscopy (in-situ DRIFTS)) and computational (computational fluid dynamics (CFD) modelling) investigation, in order to improve the performance of Ni-based DFMs. The bimetallic DFMs are comprised of a main Ni active metallic phase (20 wt%) and are modified with low Ru loadings in the 0.1–1 wt% range (to keep the material cost low), supported on Na2O/Al2O3. It is shown that the addition of even a very low Ru loading (0.1–0.2 wt%) can drastically improve the material reducibility, exposing a significantly higher amount of surface-active metallic sites, with Ru being highly dispersed over the support and the Ni phase, while also forming some small Ru particles. This manifests in a significant enhancement in the CH4 yield and the CH4 production kinetics during ICCU-Methanation (which mainly proceeds via formate intermediates), with 0.2 wt% Ru addition leading to the best results. This bimetallic DFM also shows high stability and a relatively good performance under an oxidizing CO2 capture atmosphere. The formation rate of CH4 during hydrogenation is then further validated via CFD modelling and the developed model is subsequently applied in the prediction of the effect of other parameters, including the inlet H2 concentration, inlet flow rate, dual-function material weight, and reactor internal diameter.