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.@en

In this study, Ni catalysts supported on Pr-doped CeO₂ are studied for the CO₂ methanation reaction and the effect of Pr doping on the physicochemical properties and the catalytic performance is thoroughly evaluated. It is shown, that Pr³⁺ ions can substitute Ce⁴⁺ ones in the support lattice, thereby introducing a high population of oxygen vacancies, which act as active sites for CO₂ chemisorption. Pr doping can also act to reduce the crystallite size of metallic Ni, thus promoting the active metal dispersion. Catalytic performance evaluation evidences the promoting effect of low Pr loadings (5 at% and 10 at%) towards a higher catalytic activity and lower CO₂ activation energy. On the other hand, higher Pr contents negate the positive effects on the catalytic activity by decreasing the oxygen vacancy population, thereby creating a volcano-type trend towards an optimum amount of aliovalent substitution.

@en