LAQV/Universidade Nova de Lisboa,
Keywords: nanoparticles with ionic liquids, carbon dioxide, CCS, alternatives
Summary:Carbon dioxide (CO2) is a very stable molecule and hydrogen reduction of CO2 to produce CO, the reverse water-gas shift reaction, only becomes thermodynamically favourable at temperatures higher than 1110K. CO2 emissions resulting from the consumption of carbon-based fossil fuels is (almost) universally accepted as the cause of global warming. As worldwide fossil-fuel consumption is bound to increase, so will carbon emissions, from their current level already above 30Gt/year. Carbon capture and sequestration (CCS) is currently under scrutiny at large pilot-plant level as a mitigation strategy for CO2 emission problem as well as global warming. The efficient transformation of carbon dioxide into fuels can be an excellent alternative to sequestration. In this work, we described the CO2 hydrogenation to methane using ruthenium nanoparticles prepared in situ in the presence of imidazolium based ionic liquid media. The best yield of methane (69%) was achieved using ruthenium catalyst (0.24 mol%) in 1-octyl-3-methylimidazolium bistrifluoromethanesulfonylimide [omim][NTf2] as ionic liquid and 40 bar of hydrogen pressure plus 40 bar of CO2 pressure at 150oC. Ruthenium nanoparticles (430 nm) formed in these reaction conditions are much larger than others reported in ionic liquid media. Further CO2 transformation into fuels from methane can be an excellent alternative to methanol processes.