Which technology to choose for direct electrochemical conversion of CO2 into chemicals?

Electrochemical conversion of CO2 into useful chemicals, such as carbon monoxide (CO), is a promising route for decoupling the production of industrial chemicals from the use of fossil fuels. Solid oxide electrolysis, used in Topsoe’s eCOs™ technology, stands out as particularly attractive for wider adoption due to the very high conversion efficiencies, even at industrially relevant production rates.

The chemical industry of today is largely dependent on fossil fuels and a major emitter of CO₂ and other greenhouse gases. Oil, gas, and coal are used both as feedstock and as fuel to power the chemical processes.

Since the world is attempting to curb its CO₂ footprint, emissions from the chemical industry are under increasing scrutiny. There is a growing interest both from policymakers and from the industry to adopt new, less CO₂-intensive processes for the production of chemicals.

Electrolysis is an enabling technology for decoupling the production of industrial chemicals from fossil fuels and CO₂ emissions. By combining electrolysis with low-carbon energy sources, water and CO₂ can, depending on the carbon source, be converted into chemical feedstock with a minimal or even negative carbon footprint. If successfully deployed at scale, CO₂ electrolysis technologies have the potential to radically change the way specialty and commodity chemicals are produced.

There are many emerging CO₂ electrolysis technologies out there, so the question arises – which one to use?

Topsoe has recently published a scientific review paper in the Journal of the Electrochemical Society, trying to answer this question. In the paper, three competing CO₂ electrolysis technologies - low-temperature electrolysis from aqueous solutions, molten carbonate electrolysis, and solid oxide electrolysis - were directly compared using common figures-of-merit.

Based on the analysis, CO₂ electrolysis in solid oxide cells is presently the most energy-effective and mature electrolysis technology for CO production from CO₂, outperforming aqueous electrolysis technologies by a wide margin regardless of the choice of performance metric.

Topsoe’s unique eCOs™ solution for cost-competitive onsite production of ultra-high-purity CO is based on solid oxide electrolysis technology. Topsoe has signed lease agreements for two full-size commercial plants, each with a capacity of 96 Nm³ CO per hour, with Delille Oxygen Co. The plants will be commissioned later this year.

Onsite CO generation is a significant development for the pharmaceutical, metallurgy, electronics and specialty chemicals industries that use carbon monoxide in their production processes. The eCOs™ technology ensures security of supply, eliminates the need for transporting the hazardous gas, and drastically reduces costs related to storage, rentals, and connections.