The high miscibility of H2 with scCO2to overcome the mass-transfer limitations glucose olefin aromaticIn the presence of a suitable catalyst CO2 may be hydrogenated to formic acidHomogeneously catalysed hydrogenation reactions in scCO2: the catalystsolubility problemsHeterogeneously catalysed hydrogenation reactions in scCO2: improved masstransport within catalyst pores through the low viscosity of the medium.