Very low Ru loadings boosting performance of Ni-based dual-function materials during the integrated CO2 capture and methanation process
Anastasios I. Tsiotsias (University of Western Macedonia)
Eleana Harkou (Cyprus University of Technology)
Nikolaos D. Charisiou (University of Western Macedonia)
Victor Sebastian (Universidad de Zaragoza, CIBER-BBN)
Dhanaji R. Naikwadi (TU Delft - ChemE/Catalysis Engineering)
Bart van der Linden (TU Delft - ChemE/O&O groep)
Atul Bansode (TU Delft - ChemE/Catalysis Engineering)
Dragos Stoian (European Synchrotron Radiation Facility)
Maria A. Goula (Centre for Research and Technology Hellas, University of Western Macedonia, Hellenic Open University)
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Abstract
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.