Carbon dioxide could be used as a renewable chemical feedstock. It can, for example, be reduced using H₂ to give formic acid, dimethoxymethane, or methanol. In the preparation of formate from CO₂, precious metal catalysts can achieve turn-over numbers (TONs) of up to several million. Non-precious metal catalysts, in contrast, usually only reach TONs of several thousand.

Jürgen Klankermayer and colleagues, RWTH Aachen University, Germany, have developed a nickel catalyst whose activity is comparable to precious-metal-based catalytic systems. The team used a multidentate ligand, tris(2-(diphenylphosphino)ethyl)amine), and a nickel(II) salt to prepare the catalyst (pictured). 1,8-Diazabicycloundec-7-ene (DBU) was used as a base. The reaction was performed under 30 bar CO₂ pressure and a total pressure of 90 bar including H₂.

At optimized reaction conditions, the catalyst achieved TONs of up to 4.65 · 10⁶ in the homogeneous hydrogenation of CO₂ to formate. The system, thus, outperforms other systems based on first-row transition metals. According to the researchers, detailed mechanistic investigations on the catalyst system are ongoing.

• A highly active non-precious transition metal catalyst for the hydrogenation of carbon dioxide to formates,
  Benjamin G. Schieweck, Niklas F. Westhues, Jürgen Klankermayer,
  Chem. Sci. 2019.
  https://doi.org/10.1039/c8sc05230a