EFFECT OF THERMAL CONDUCTIVY OF Ru/Al2O3 CATALYST DISPERSED ON POLYMER DERIVED SiC FOAM SUBSTRATE FOR CO2 METHANATION

The increasing levels of CO2 in the atmosphere and the consequent global warming effect require the development of techniques for CO2 capture. In addition, conversion of captured CO2 into fuels such as methane (Power-to-Gas process) represents a carbon-neutral and green solution if captured CO2 is reacted with hydrogen from renewable sources producing a synthetic substitute of natural gas (SNG) which can be transported using the existing infrastructure for natural gas distribution. The hydrogenation of CO2 to give methane, the Sabatier reaction, is an exothermic equilibrium process (?H=-165 kJ/mol). Catalysts, such as Ru, Ni, Fe, Co or Rh, dispersed on oxide supports are necessary to achieve good rates and selectivity to CH4. High surface temperature can displace the thermodynamic equilibrium and promote side reactions, as RWGS. The use of materials with a high thermal conductivity of support and/or substrate can help to suitably manage the exothermal effect of the reaction increasing the catalytic performance. In this work, polymer derived SiC foams treated at different temperatures were proposed as substrate for 1%Ru/Al2O3 catalyst for CO2 hydrogenation to methane. The catalysts, as foam disks with different load of the active phase, were tested in a fixed bed reactor in the temperature range 200-450°C with a CO2/H2/N2 = 1/4/5 mixture varying the total flow rate. CO2 capture capacity depends on the Ru/alumina load whereas the performance is affected by the different thermal pre-treatment of the substrate providing different thermal conductivity properties to SiC foam material.