# Formylation–Decarbonylation Relay Strategy for the Selective Hydrogenation of CO2 to CO

## TL;DR

Scientists developed a new method using a ruthenium complex and amine to efficiently convert CO2 into CO with high selectivity.

## Contribution

A novel formylation-decarbonylation relay strategy is introduced for selective CO2 hydrogenation to CO.

## Key findings

- A ruthenium pincer complex and amine achieved a TON of 249 for CO2 hydrogenation to CO with 100% selectivity.
- Formylation and decarbonylation steps were studied using catalytic optimization and DFT computations.
- The reaction was conducted at 70 bar, 170 °C for 90 hours using morpholine and Ru-MACHO catalyst.

## Abstract

We report here an alternative approach to conducting
the reverse
water–gas shift (RWGS) reaction catalyzed by a ruthenium pincer
complex and an amine. In this strategy, a secondary amine is first
formylated by CO2 and H2 to make H2O and formamide. The formamide then undergoes decarbonylation to
produce CO with the concomitant regeneration of the amine. Both steps,
formylation and decarbonylation, were independently investigated through
catalytic optimization studies and DFT computations at the PBE0-D3­(BJ)PCM(THF)/def2-TZVP level. Using morpholine and Ru-MACHO pincer
catalyst, a TON of 249 was achieved for the hydrogenation of CO2 to CO (at 70 bar, 170 °C for 90 h) with 100% selectivity.