Ethoxyethanol solution, alkaline aqueous

A very pronounced synergistic effect is found for binary ruthenium-iron carbonyl catalysts in the water-gas shift reaction. Both mixed ruthenium-iron clusters and mixtures of ruthenium clusters with iron complexes are considerably more active in basic solutions. Whereas the water-gas shift activity (moles of H2 per mole of complex per day) of alkaline aqueous ethoxyethanol solutions of Ru3(CO)12 and Fe(CO)j is... 

The first published report on the homogeneous catalysis of the WGSR by soluble transition metals complexes in alkaline solutions was based on the use of Ru3(CO)i2 in aqueous 2-ethoxyethanol solutions of KOH under 1 atm CO at 100°C (13). This was immediately followed by a report that related metal carbonyl complexes are active for WGSR catalysis in the presence of amines (14). A large number of other transition metal carbonyl complexes have since been demonstrated to be active WGSR catalysts under basic conditions (17,18). 

A report in 1977 (3) of an active system prepared from [Rh(CO)2CI]2, CH3CO2H, cone. HC1 and Nal in water demonstrated that a basic medium is not a necessary condition for WGSR catalysis. This result stimulated us to examine the potential activity of several simple metal carbonyls in acidic solution as well. Attempts with Fe(CO)5 and Iri (CO)12 (17), both active in alkaline and amine solutions, proved unfruitful. However Ru3(CO)12 in acidic (0.5 N H2SOtf) aqueous ethoxyethanol gave WGSR activity substantilly larger than found in basic solutions under otherwise analogous conditions (Pco=0.9 atm, T=100°C, [Ru]Total=0 036 mol/L) (15). This solution proved unstable and... 

Alkaline solutions of Ru(CO)t2 (KOH in aqueous ethoxyethanol) have also been found to catalytically decompose formic acid (5 7,5S). Presumably this occurs by way of anionic ruthenium hydride derivatives [e.g., HRu3(CO)7,] reacting with HCOOH to provide a ruthenium formate derivative and H2. Subsequent / -elimination of hydride from the ruthenium formate led to regenerating the anionic ruthenium hydride species and carbon dioxide. We have recently synthesized and fully characterized a possible ruthenium formato intermediate for this process, Ru3(CO),0-(02CH) (9) (59). Indeed this species in part extrudes C02 in the presence of CO with concomitant production of Ru3(CO),, H. ... 

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