Homogeneous Catalytic Hydrogenation of CO₂ to Methanol – Improvements with Tailored Ligands

Abstract

Improved molecularly-defined cobalt catalysts for the hydrogenation of carbon dioxide to methanol have been developed. A key factor for increased productivity (up to twofold compared to previous state-of-the-art-system) is the specific nature of substituents on the triphos ligand. In addition, the effect of metal precursors, and variations of additives have been investigated.

CO2 Reduction to Methanol in the Liquid Phase: A Review

“…Following this work, an improved cobalt catalyst was developed by changing the substituents on the Triphos ligand. [61] Unfortunately, the catalytic system only gave a low TON of 79, which is slightly higher than that with the [Co(acac) 3 ]-Triphos-HNTf 2 catalyst. Activation of the Co precursor plays a vital role in determining the catalyst's catalytic activity on the CO 2 hydrogenation to methanol.…”

Mild and Selective Carbon Dioxide Hydroboration to Methoxyboranes Catalyzed by Mn(I) PNP Pincer Complexes

“…Among first‐row transition metals, cobalt‐catalyzed CO 2 hydrogenation to MeOH under acidic conditions was demonstrated by de Bruin and co‐workers via intermediate ester hydrogenation, and by Beller and co‐workers in the presence of triphos and Co(acac) 3 with HNTf 2 in THF/ethanol, reaching a TON of 50 . Further optimization was then carried out, and in the presence of modified triphos ligands and Co(NTf 2 ) 2 as metal precursor, TON was increased up to 125 …”

“…[23] Further optimization was then carried out, and in the presence of modified triphos ligands and Co(NTf 2 ) 2 as metal precursor, TON was increased up to 125. [24] Although H 2 is the most atom-efficient, economical and sustainable reductant when produced from non-fossil, renewable feedstocks, some concerns are still present, due to safety risks connected with the use of flammable, pressurized gas. For this reason, chemists have looked for alternative reductants to bring about CO 2 reduction to MeOH.…”

Poly(ethyleneimine)‐Mediated Consecutive Hydrogenation of Carbon Dioxide to Methanol with Ru Catalysts

“…In addition to these Ru complexes, an Ir‐based catalyst was recently applied for consecutive transformations involving the hydrogenation of CO 2 and simultaneous disproportionation of HCO 2 H to afford methanol . Non‐precious metal complexes have also been successfully used for direct methanol synthesis; Mn, Fe, and Co, complexes have newly emerged as promising catalysts.…”