Investigation of Hydrogenation of Formic Acid to Methanol using H₂ or Formic Acid as a Hydrogen Source

Abstract

Production of methanol (MeOH) from CO 2 is strongly desired as a key chemical feedstock and a fuel. However, the conventional process requires elevated temperature and pressure, and high temperature restricts the productivity of MeOH due to equilibrium limitations between CO 2 and MeOH. This paper describes the efficient hydrogenation/disproportionation of formic acid (FA) to MeOH by using iridium catalysts with electronically tuned ligands and by optimizing reaction conditions. An iridium complex bearing 5,5′-dimethyl-2,2′bipyridine in FA hydrogenation achieved MeOH selectivity with H 2 of up to 47.1% for FA hydrogenation under 4.5 MPa of H 2 in the presence of H 2 SO 4 . The final concentration of MeOH of 3.9 M and a TON of 1314 were obtained in 12 M FA aqueous solution including 10 mol % of H 2 SO 4 at 60 °C under 5.2 MPa of H 2 . Even under atmospheric pressure without introduction of external hydrogen gas, the FA disproportionation under deuterated conditions produced MeOH with 15.4% selectivity. Furthermore, the isotope effect and NMR studies revealed mechanistic insight into the catalytic hydrogenation of FA to MeOH.

Catalytic Disproportionation of Formic Acid to Methanol by an Iridium Complex Immobilized on Bipyridine‐Periodic Mesoporous Organosilica

“…[2,11] This is reasonable because the H 2 / CO 2 pressure suppresses the excess FA dehydrogenation (Scheme 2) and promotes the FA hydrogenation to produce MeOH (Scheme 3). [2,11] This is reasonable because the H 2 / CO 2 pressure suppresses the excess FA dehydrogenation (Scheme 2) and promotes the FA hydrogenation to produce MeOH (Scheme 3).…”

“…Miller and Goldberg et al reported the disproportionation of FA to MeOH with homogeneous [IrCp*(bpy)(H 2 O)](OTf) 2 (bpy = 2,2'-bipyridine) in a closed system using 12 M FA (selectivity: 12.0 %). [11] Cantat et al reported the highly selective MeOH generation using ruthenium catalysts and methanesulfonic acid as an acid additive in a closed system at 150°C (selectivity: 50.2 %). [11] Cantat et al reported the highly selective MeOH generation using ruthenium catalysts and methanesulfonic acid as an acid additive in a closed system at 150°C (selectivity: 50.2 %).…”

“…[11] Cantat et al reported the highly selective MeOH generation using ruthenium catalysts and methanesulfonic acid as an acid additive in a closed system at 150°C (selectivity: 50.2 %). [2,11] Since reaction system under atmospheric pressure (open system) would be more desirable for easy handling, a new approach is needed to improve MeOH selectivity of the disproportionation of FA under atmospheric pressure. It is known that the disproportionation of FA is composed of dehydrogenation of FA (Scheme 2) and hydrogenation of FA by produced H 2 (Scheme 3).…”

Biogenic Formic Acid as a Green Hydrogen Carrier

“…FA can be used as hydrogen source for the hydrogenation of FA to methanol. Himeda et al . achieved up to 47.1 % selectivity to methanol in a homogeneously catalyzed disproportion of FA with the combined hydrogenation to methanol.…”

Formates for green catalytic reductions via CO2 hydrogenation, mediated by magnetically recoverable catalysts

“…Furthermore, direct catalytic hydrogenation may have selectivity problems especially in the presence of the highly active heterogeneous precious metal catalysts [7,8]. It is well known, that CO 2 can be catalytically reduced by H 2 to various products such as hydrocarbons, carboxylic acids, aldehydes and alcohols by homogeneous or heterogeneous way [9][10][11][12].…”