Free formic acid by hydrogenation of carbon dioxide in sodium formate solutions
Free formic acid was produced in hydrogenation of carbon dioxide dissolved in aqueous sodium formate solutions under H2 and CO2 pressure with the water-soluble rhodium–phosphine complex, [RhCl(mtppms)3] (mtppms = monosulfonated triphenylphosphine) as catalyst. Concentration of sodium formate, total gas pressure and the pressure ratio of H2 to CO2 were the most important factors for production of HCOOH. Up to 0.13 M concentration of HCOOH was achieved, while there was negligible formic acid production in the absence of sodium formate.
Graphical abstractCatalytic hydrogenation of carbon dioxide to free formic acid (not to formate salts) was feasible in aqueous sodium formate solution as solvent, but was negligible in neat water.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Hydrogenation of CO2 was catalyzed by a water-soluble rhodium(I)-phosphine complex. ► Aqueous sodium formate solutions were used as solvent. ► Free HCOOH (rather than formate salts) was obtained up to 0.13 M concentration. ► There was negligible formation of HCOOH in the absence of HCOONa. ► High total gas pressure and high CO2 partial pressure promoted formation of HCOOH.
Journal: Catalysis Communications - Volume 14, Issue 1, 25 October 2011, Pages 74–76