Periodic Reporting for period 2 - DualFlow (Dual circuit flow battery for hydrogen and value added chemical production)
Reporting period: 2023-10-01 to 2025-03-31
The EU-funded DualFlow project will introduce a new energy conversion and storage concept combining battery storage, hydrogen generation and production of useful chemicals into a single hybrid system using water-soluble redox mediators as energy transfer vectors. The system will be used for storing electricity or for converting renewable energy into hydrogen and value-added chemicals.
Current electrolyzer technologies are designed to be operated 8000 h per year. However, access to a continuous supply of green electricity will be unlikely given the recent trend in the increasing share of intermittent electricity being produced by solar and wind power. Therefore, systems able to flexibly utilize green electricity are a key to resolving this critical issue. Alkaline electrolysis has been optimized for efficient hydrogen production during the last 100 years, utilizing nickel-based catalysts and porous separators, and therefore it is exceedingly difficult to compete with it. Electrolysis produces oxygen, typically vented into the atmosphere, as a side-product and a way to bring down hydrogen cost is to produce added value chemicals instead of oxygen. As the scale of the hydrogen production is immense, the matching reaction on the positive side should also be suitable for large scale operation. DualFlow pursues a novel approach for solving the challenge, by producing hydrogen together with decarbonized chemicals. A hydrogen production unit will be incorporated as an additional part of a flow battery, only utilized when renewable energy is available in large quantities and the battery is fully charged. This means that the reactors where hydrogen production and the corresponding oxidation take place need to be simple and inexpensive, to justify additional costs of the unit that is used only when renewable energy production is high. Such a system will have lower efficiency than a commercial electrolyzer but will allow more flexible operation. Coupled together with production of chemicals, DualFlow will pave the way for a cost-competitive, sustainable, and flexible approach to energy storage and green hydrogen production.
The objectives of DualFlow are to:
1) Realize a proof-of-concept hybridized (alkaline) hydrogen production redox flow battery system. Specifically, DualFlow will demonstrate combined hydrogen production and electricity storage capability on a lab-scale by harnessing abundant and environmentally benign materials.
2) Develop processes to enable production of decarbonized chemicals. Specifically, we will demonstrate the continuous operation of an oxidation process in a biphasic system to produce thin poly(3,4-ethylenedioxythiophene) (PEDOT) films. The developed system will be adaptable to other reactions.
3) Realize a proof-of-concept production of chemicals. Specifically, we will demonstrate production of PEDOT, lidocaine and levetiracetam, and production of nanocellulose via mediated oxidation of cellulose.
Current electrolyzer technologies are designed to be operated 8000 h per year. However, access to a continuous supply of green electricity will be unlikely given the recent trend in the increasing share of intermittent electricity being produced by solar and wind power. Therefore, systems able to flexibly utilize green electricity are a key to resolving this critical issue. Alkaline electrolysis has been optimized for efficient hydrogen production during the last 100 years, utilizing nickel-based catalysts and porous separators, and therefore it is exceedingly difficult to compete with it. Electrolysis produces oxygen, typically vented into the atmosphere, as a side-product and a way to bring down hydrogen cost is to produce added value chemicals instead of oxygen. As the scale of the hydrogen production is immense, the matching reaction on the positive side should also be suitable for large scale operation. DualFlow pursues a novel approach for solving the challenge, by producing hydrogen together with decarbonized chemicals. A hydrogen production unit will be incorporated as an additional part of a flow battery, only utilized when renewable energy is available in large quantities and the battery is fully charged. This means that the reactors where hydrogen production and the corresponding oxidation take place need to be simple and inexpensive, to justify additional costs of the unit that is used only when renewable energy production is high. Such a system will have lower efficiency than a commercial electrolyzer but will allow more flexible operation. Coupled together with production of chemicals, DualFlow will pave the way for a cost-competitive, sustainable, and flexible approach to energy storage and green hydrogen production.
The objectives of DualFlow are to:
1) Realize a proof-of-concept hybridized (alkaline) hydrogen production redox flow battery system. Specifically, DualFlow will demonstrate combined hydrogen production and electricity storage capability on a lab-scale by harnessing abundant and environmentally benign materials.
2) Develop processes to enable production of decarbonized chemicals. Specifically, we will demonstrate the continuous operation of an oxidation process in a biphasic system to produce thin poly(3,4-ethylenedioxythiophene) (PEDOT) films. The developed system will be adaptable to other reactions.
3) Realize a proof-of-concept production of chemicals. Specifically, we will demonstrate production of PEDOT, lidocaine and levetiracetam, and production of nanocellulose via mediated oxidation of cellulose.
We have continued to synthesize and test various candidates for alkaline flow batteries, and started developing catalysts for hydrogen evolution. Sufficiently stable candidates for realizing the demonstrator have been identified. We have demonstrated utilization of Fe-species as redox mediators, enabling coupling with a flow battery, and also demonstrated production of PEDOT, lidocaine and levetiracetam and nanocellulose as well as several other chemicals.
Systematic screening of suitable metal complexes and synthesis of 80+ different complexes has been carried out. The starting points have been Fe, Ni, Cr, Ti, Fe and Mn with ligands based on phenols and carboxylic acids. The Fe, Ni, Cr, Cu and Mn complexes have been synthesized by mixing stoichiometric amounts of the soluble metal salts with the ligand, although optimization for the pH as well as order of mixing has been required. To accelerate this step, automated synthesis has been utilized. Focus has been on developing a custom made robot moving electrodes from one well to the next. At this stage, we have developed and implemented of a semi-automated system for electrochemical measurements, advancing the high-throughput screening of redox-active materials for energy storage applications. This screening has been followed by synthesis and more detailed characterization of the most promising mediators.
For hydrogen evolution catalysts, benchmarking of catalysts was finalized and we also developed different methodologies to monitor the progress of the HER in the mediated process. Overall, we have successfully demonstrated alkaline HER using different mediator solutions over a range of catalysts, and are in progress of designing the reactor for mediated hydrogen evolution.
For chemical synthesis, commercial Fe(III) species were shown to be capable of generating PEDOT thin films at polarized liquid|liquid interfaces. A previously unknown catalyst effect for pre-oligomerization of EDOT using dissolved O2 in the organic phase as the oxidant was discovered and studied in depth. This catalysis effect opens opportunities to enhance the kinetics of interfacial electrosynthesis by weak oxidants. Cellulose nanocrystals with high carboxylate content were successfully produced and characterised by mediated electrosynthesis. The method has proven reproducible and upscaling wiht a flow cell was started. Hydrogels were successfully prepared and partially characterised. A scalable and efficient electrochemical protocol was developed for the oxidation of alcohols to aldehydes. This method was then applied to synthesise drug intermediates for trenbolone, nomegestrol and an HIV protease inhibitor. Compatibility with an aqueous/alkaline electrolyte and flow operation was demonstrated. A novel electrochemical method for generating isocyanides from aminotetrazoles was developed and scaled up in continuous flow. The reaction showed broad functional group tolerance and high yields. Integration with the DualFlow architecture was confirmed through mediated oxidation. Lidocaine synthesis was demonstrated via an Ugi reaction using electrogenerated isocyanides.
The first complete demonstration of decoupled water electrolysis has been executed. Key results demonstrated efficient electrolysis at room temperature using only 1.6 V cell voltage.. Preliminary planning and setup development have been conducted for the electrosynthesis of value added chemicals.
Systematic screening of suitable metal complexes and synthesis of 80+ different complexes has been carried out. The starting points have been Fe, Ni, Cr, Ti, Fe and Mn with ligands based on phenols and carboxylic acids. The Fe, Ni, Cr, Cu and Mn complexes have been synthesized by mixing stoichiometric amounts of the soluble metal salts with the ligand, although optimization for the pH as well as order of mixing has been required. To accelerate this step, automated synthesis has been utilized. Focus has been on developing a custom made robot moving electrodes from one well to the next. At this stage, we have developed and implemented of a semi-automated system for electrochemical measurements, advancing the high-throughput screening of redox-active materials for energy storage applications. This screening has been followed by synthesis and more detailed characterization of the most promising mediators.
For hydrogen evolution catalysts, benchmarking of catalysts was finalized and we also developed different methodologies to monitor the progress of the HER in the mediated process. Overall, we have successfully demonstrated alkaline HER using different mediator solutions over a range of catalysts, and are in progress of designing the reactor for mediated hydrogen evolution.
For chemical synthesis, commercial Fe(III) species were shown to be capable of generating PEDOT thin films at polarized liquid|liquid interfaces. A previously unknown catalyst effect for pre-oligomerization of EDOT using dissolved O2 in the organic phase as the oxidant was discovered and studied in depth. This catalysis effect opens opportunities to enhance the kinetics of interfacial electrosynthesis by weak oxidants. Cellulose nanocrystals with high carboxylate content were successfully produced and characterised by mediated electrosynthesis. The method has proven reproducible and upscaling wiht a flow cell was started. Hydrogels were successfully prepared and partially characterised. A scalable and efficient electrochemical protocol was developed for the oxidation of alcohols to aldehydes. This method was then applied to synthesise drug intermediates for trenbolone, nomegestrol and an HIV protease inhibitor. Compatibility with an aqueous/alkaline electrolyte and flow operation was demonstrated. A novel electrochemical method for generating isocyanides from aminotetrazoles was developed and scaled up in continuous flow. The reaction showed broad functional group tolerance and high yields. Integration with the DualFlow architecture was confirmed through mediated oxidation. Lidocaine synthesis was demonstrated via an Ugi reaction using electrogenerated isocyanides.
The first complete demonstration of decoupled water electrolysis has been executed. Key results demonstrated efficient electrolysis at room temperature using only 1.6 V cell voltage.. Preliminary planning and setup development have been conducted for the electrosynthesis of value added chemicals.
DualFlow has advanced beyond the state of the art by developing high-throughput screening methods of redox-active materials for energy storage applications, discovered a novel catalytic effect for significantly accelerating formation of PEDOT films at liquid-liquid interfaces by weak oxidants, produced cellulose nanocrystals with high carboxylate content. A scalable and efficient electrochemical protocol was developed for the oxidation of alcohols to aldehydes by mediators. This method was then applied to synthesise drug intermediates for trenbolone, nomegestrol and an HIV protease inhibitor. A novel electrochemical method for generating isocyanides from aminotetrazoles was developed and scaled up in continuous flow. Lidocaine synthesis was demonstrated via an Ugi reaction using electrogenerated isocyanides.