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.

Climate change, the greenhouse effect and fossil fuel extraction have gained a growing interest in research and industrial circles to provide alternative chemicals and fuel synthesis technologies. Carbon dioxide (CO₂) hydrogenation to value-added chemicals using hydrogen (H₂) from renewable power (solar, wind) offers a unique solution. From this aspect this review describes the various products, namely methane (C₁), methanol, ethanol, dimethyl ether (DME) and hydrocarbons (HC_s) originating via CO₂ hydrogenation reaction. In addition, conventional reactor units for the CO₂ hydrogenation process are explained, as well as different types of microreactors with key pathways to determine catalyst activity and selectivity of the value-added chemicals. Finally, limitations between conventional units and microreactors and future directions for CO₂ hydrogenation are detailed and discussed. The benefits of such set-ups in providing platforms that could be utilized in the future for major scale-up and industrial operation are also emphasized.