Catalytic CO₂ Hydrogenation to Formate by a Ruthenium Pincer Complex

Abstract

This paper reports the hydrogenation of carbon dioxide to formate catalyzed by the Ru pincer complex Ru(PNN)CO(H) (PNN = 6-(di-tert-butylphosphinomethylene)-2-(N,N-diethylaminomethyl)-1,6-dihydropyridine). Stoichiometric studies are presented that support the feasibility of the individual steps in a proposed catalytic cycle for this transformation. The influence of base and solvent on catalyst performance is explored. Overall, under optimized conditions (using diglyme as the solvent and potassium carbonate as the base) up to 23,000 turnovers of formate and a turnover frequency of up to 2,200 h–1 can be achieved.

Advances in Ruthenium Catalysed Hydrogen Release from C1 Storage Materials

“…One recent example of this reversibility is the publication by Sanford et al which makes use of a PNN ruthenium-pincer complex to hydrogenate carbon dioxide in the presence of a base. High turnover frequencies of > 2 200 h -1 were reported and the formic acid that was produced was shown to be able to be further modified in the presence of methanol to form methyl formate; this could subsequently be hydrogenated to give two equivalents of methanol [99]. Alternative methods for carbon dioxide hydrogenation include the use of aryl ruthenium complexes such as that reported by Byers and co-workers [100].…”

Hydrogenation of Polar Bonds Catalysed by Ruthenium-Pincer Complexes

“…Sanford and co-workers subjected our catalyst (2) for highly efficient catalytic hydrogenation of CO 2 to formate salts [97] and displays similar activity to known Nozaki's Ir(III) pincer catalyst 27 (TON ¼ 3,500,000 and TOF ¼ 150,000 h À1 for CO 2 to HC(O)OK) [98,99]. Heating a diglyme solution of complex 2, base (K 2 CO 3 ), carbon dioxide, and hydrogen resulted in the formation of potassium formate with excellent TON of 23,000 and TOF of up to 2,200 h À1 .…”

Application of Ni–Al-hydrotalcite-derived catalyst modified with Fe or Mg in CO2 methanation

“…The hydrogenation of CO 2 can produce more useful fuels and chemicals. Currently, the products of CO 2 hydrogenation being researched include carbon monoxide, methane, methanol, ethanol or higher alcohol, hydrocarbons, dimethyl ether, formic acid, formates, and formamides [8][9][10][11]. Some of these products can be used as fuels in internal combustion engines and as raw materials and intermediates in many chemical industries.…”