Selective Electrochemical Reduction of CO2 to High Value Chemicals

Project Information

SELECTCO2

Grant agreement ID: 851441

DOI

10.3030/851441

Project closed

EC signature date 21 October 2019

Start date 1 January 2020

End date 31 March 2023

Funded under

• SOCIETAL CHALLENGES - Secure, clean and efficient energy

Total cost

€ 3 971 832,50

EU contribution

€ 3 772 265,00

Coordinated by

DANMARKS TEKNISKE UNIVERSITET
Denmark

Periodic Reporting for period 2 - SELECTCO2 (Selective Electrochemical Reduction of CO2 to High Value Chemicals)

Reporting period: 2021-07-01 to 2023-03-31

Summary of the context and overall objectives of the project

With 195 nations signing the Paris Climate Accord, the world has acknowledged anthropogenic induced climate change and the need for action with EU’s approach to action based on the strategic energy technology plan (SET Plan). While fossil fuels accounts for contributes the vast majority of the anthropogenic effects from CO2 emissions, they are used in diverse, but essential fields, such as heating, transport, power generation, industry and even as the primary raw material for the entire chemicals industry. While many of these fields have established sustainable options, there are others, which are at early stages of development which need rapid development to form the complete backbone of the energy system by 2030 and 2050. One of the most EU essential and challenging areas in need of development is the conversion to a sustainable chemicals industry.

SELECTCO2 aimed to contribute to the electrification of the chemicals industry through the development of highly selective and efficient devices for the conversion of CO2 to high value products at low temperatures and pressures. It is well known in the chemicals industry that costs due to separations can amount to 60-80% of the total costs of the chemicals. This same general cost percentage holds in bio-based chemicals as well. Electrochemical CO2 Reduction (ECO2R) allows the unique ability to start with a single reactant in CO2 and use catalysis to build up selectively to a given molecule. Direct conversion to a specific product allows for the mitigation or even elimination of separation costs and can greatly reduce the costs of producing a given chemical.

To create immediate impact and to provide the backbone for the emerging sustainable chemicals and fuel industry, we we created lab scale devices capable of electrochemically converting CO2 selectively into either carbon monoxide (>90%), ethanol/acetaldehyde, (>80 %), or ethylene (>90%) at high thermodynamic efficiencies (> 40%). To achieve this SELECTCO2 has a number of Objectives relating to this.

The first objective relates to improved catalysts for carbon monoxide, ethanol/acetaldehyde, and ethylene. The second objective is to develop stable gas diffusion layers to support the catalysts and allow efficient mass transfer of reactants and products. The third objective is to develop membranes and ionomers to allow for efficient ion transfer to and from the catalysts. The fourth objective is to develop accurate mass transfer models to maximize the rate of electrochemical CO2 reduction. The final objective is to analyze the societal implications of this technology.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

In the initial period we developed strong links between work packages and discovered how to operate in a Covid-19 environment. CO Catalysis has been highly successful in developing single site catalysts based off metal incorporated nitrogen doped graphitic carbon based off computational discoveries. The resultant Ni based catalysts resulted in 90% selectivity to CO at 250 mA/cm2. For ethanol catalysis it was found that a Cu0.6Ag0.4 composite allows for increased ethanol selectivity slightly. Computational discoveries have discovered the branching point between ethanol and ethylene selectivity. The best membranes have operated for 200 hours with ~5% increase in voltage and no noticeable variation in product selectivity. GDL tomography has been accomplished as well as a continuum-scale device model improving mas transfer understanding. Additionally Life Cycle Assessment (LCA); Life Cycle Costing (LCC) analysis; and Social Life Cycle Assessment (S-LCA) was applied to CO2 conversion to CO, ethanol, and ethylene.

In the second period, CO2 to CO catalysts were further refined allowing us to reach our objectives in terms of CO2 to CO catalyst performance. The computationally discovered branching point between ethylene and ethanol entailed that it was incredibly hard to control this selectivity. CO2 crossover was a substantial issue, however switching to CO electrolysis for ethanol and ethylene was a very effective means to resolve this. Cathode flooding was a notable issue, which was discovered to be strongly influenced by salt precipitation. A variety of techniques were used to mitigate this, entailing multiple consortium members were able to achieve >100 hour stability for their CO2 electrolysis reactors. Mass transfer modeling, which integrated catalytic reaction rates covered from the nanometer to the millimeter scale allowing for highly beneficial understanding of device perfromance. Technoeconomics showed that CO had the most promise, but all productfeasibility was greatly dependent upon electricity prices.

The overall conclusions of the action is that SELECTCO2 was successful in taking CO2 electrolysis from a TRL2 level to a TRL4 level. The CO2 to CO catalysts are exceptional in terms of both activity and selectivity. The CO2 to ethanol and ethylene catalysts could not isolate either of these products, but we could mitigate other products. As ethanol and ethylene can be thermally converted between each other via a hydrogenation/dehydrogenation procedure, the results indicate that future work should focus on combined ethylene+ethanol selectivity. With membranes we found the importance of excess of reactants was essential for an optimal membrane synthesis. Optimized gas diffusion layers were not only stable, but also able to achieve greater than 1 A/cm2 performance.. We were also able to accurately model device performance, thus demonstrating a comprehensive understanding of the major phenomena controlling the performance. Technoeconomic analysis showed this was a worthwhile technology for further investment.

The project produced 19 publications with approximately 19 more manuscripts being prepared for publications. Including both scientists, general public and others, it is estimated that the SELECTCO2 project reached 60,000 people. There were 2 patents either applied for or are in the process of being applied for.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

We improved both the intrinsic activity and selectivity of catalysts for CO, ethanol and ethylene. For catalyst geared towards CO, the focus was on non-noble metal catalysts, which pushed the state of the art further in terms of single site catalysts. The discovery of the branching point between ethylene and ethanol was a huge breakthrough in the field. Furthermore SELECTCO2 pushed the fields of durability having multiple experiments of over 100 hours with different reactor designs and partners, thus pushing the benchmark for durability to higher TRL levels. The largest, yet hardest to define, impact from this work is the development of a combined expertise approach to improving CO2 electrolysis performance. The numerous publications with membrane, gas diffusion layer, modeling, and catalyst people all working in unison demonstrates the approach moving forward with such complex devices as these reactors.

In terms of wider societal implications SELECTCO2 demonstrated this technology is developing towards higher TRL levels and roadblocks that have been presented have been overcome. The project also showed that the field is ready for higher TRL level type projects and entities that are more geared to this can play a increasingly significant role in helping develop the technology to full commercialization.

Overall Description of SELECTCO2