Ru/Al2O3 on Polymer-Derived SiC Foams as Structured Catalysts for CO2 Methanation

The catalytic methanation of CO2 via the strongly exothermic equilibrium Sabatier reaction requires the development of structured catalysts with enhanced mass- and heat-transfer features to limit hot-spot formation, avoid catalyst deactivation, and control process selectivity. In this work, we investigated the use of polymer-derived SiC open-cell foams as structured carriers onto which gamma-Al2O3 was applied by either dip-coating or pore-filling methods; eventually, Ru was dispersed by impregnation. The formation of an undesired insulating SiO2 layer on the surface of the SiC struts was prevented by a pyrolysis treatment under an inert atmosphere at temperatures varying from 800 up to 1800 degrees C. SiC foam substrates and their corresponding structured catalysts were characterized by SEM, XRD, N-2 physisorption, and compressive strength measurements, and their CO2 methanation activity was tested at atmospheric pressure in a fixed bed flow reactor operated in the temperature range from 200 to 450 degrees C. SiC foams obtained at intermediate pyrolysis temperatures (1000-1200 degrees C) showed good mechanical strength and high compatibility with the Ru/Al2O3 active catalytic overlayer.