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Research of Eric Schuler and co-workers at the Industrial Sustainable Chemistry group features at the cover of Green Chemistry, a journal of the Royal Society of Chemistry. Together with colleagues from the Catalysis Engineering group and in cooperation with researchers from the University of Manchester, they present a ‘perspective’ paper that draws a comprehensive picture of formate as a potential key intermediate in carbon dioxide utilization. It contains an overview of the history and chemical details of the coupling reaction of two formate molecules to oxalate, and provides an outlook on its potential for industrial value chains for producing CO2-based chemicals and polymers.

The cover of Green Chemistry. The illustration was prepared by first author of the paper Eric Schuler. Image: Green Chemistry.

Replacing fossil feedstocks for chemicals and polymers in the chemical industry is a key step towards a future circular society. CO2 offers a great opportunity as a starting material for new fossil-free value chains. However, since CO2 has a very low reactivity, its conversion requires either high energy inputs or nifty catalytic systems. An example of the latter can be found in an electrochemical cell using a gas-diffusion electrode to convert CO2 into formate. To further fulfil the promises of this first step in CO2 utilization, a conversion path needs to be developed that connects formate to existing or novel chemical synthesis routes suitable for large-scale industrial application.

In their perspective article, Schuler and co-workers focus on the coupling of two formates to oxalate and explore alternative coupling partners for formate to unlock its full potential. Oxalate or oxalic acid is considered a potential versatile ‘platform chemical’ for materials production. It can for instance be further converted towards glycolic acid and other useful monomers that enable the synthesis of renewable plastics. Thus, the formate-to-oxalate coupling reaction, or FOCR, can be considered as a crucial step in the chemical conversion route from CO2 towards valuable products.

Most recent advances and challenges

As the paper describes, the FOCR has been studied for more than 175 years and has even seen an industrial use in the past. It presents the history of the FOCR, discusses the most recent advances and challenges for its implementation in CO2 utilization processes in the future. The authors provide an overview of the various reaction parameters and their ability to influence the reaction and products that can be obtained. To understand the reaction better and improve it in the future, they critically discuss the many mechanisms proposed for the various catalytic systems in the FOCR. Finally, they explore the potential to introduce new catalytic and solvent systems or co-reactants to the FOCR, to improve reaction performance and broaden the range of products from CO2 derived formate.

Route for polymers from CO2 via (i) electrochemical reduction to formate, (ii) thermal formate coupling to oxalate, (iii) electrochemicaloxalate acidification, (iv) thermocatalytic reduction of oxalic acid to glycolic acid, and (v) polymer production from oxalic acid and its derivatives. This route is being researched in the European Horizon 2020 project OCEAN. Image: HIMS.

Paper details

Eric Schuler, Michele Morana, Pavel A. Ermolich, Kristian Lüschen, Adam J. Greer, S. F. Rebecca Taylor, Christopher Hardacre, N. Raveendran Shiju and Gert-Jan M. Gruter: Formate as a key intermediate in CO2 utilization Green Chem.,2022, 24, 8227-8258 DOI: 10.1039/D2GC02220F, cover: 10.1039/D2GC90097A

See also