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DistributEd Chemicals And fuels production from CO2 in photoelectrocatalytic DEvices

Periodic Reporting for period 1 - DECADE (DistributEd Chemicals And fuels production from CO2 in photoelectrocatalytic DEvices)

Reporting period: 2020-05-01 to 2021-10-31

Integrated devices for the distributed production of chemicals and fuels from CO2, H2O and solar energy are a key element for the transition to a low-carbon and more sustainable model of economic development. Efficient and integrated photoelectrocatalytic (PEC) devices are able to use directly solar energy to produce chemicals and energy vectors from small molecules such as CO2 and H2O.

Thus, double benefit is realized: 1) emitted CO2 becomes a raw C-source rather than a waste, thus responding to the concept of circularity, and 2) the reaction of CO2 conversion becomes an efficient way to introduce renewable energy in the process. There are thus many beneficial effects:
1) reduction of CO2 emissions with a functional closing of the carbon-cycle,
2) lowering of the carbon footprint (reuse of CO2 and substituting with renewable energy the fossil energy sources to produce the final products)
3) increasing process productivity and economics.

The overall objective of the DECADE project is to develop a novel photoelectrocatalytic (PEC) device that would use waste CO2 and bio-alcohols as feeding inputs to synthetize value-added products. The novel element of the designed PEC device would be the enhanced energy efficiency, as the device in designed to exploit both sides of the electro-catalytic cells to produce the same chemicals and integrates a PV cell to drive the reaction by sunlight. The target products, the production of which would be optimized, are ethyl acetate (EA) and ethyl formate (EF). These products are used as green solvents/chemicals or fuel additives (octane booster). As an alternative, the production of methyl formate (MF) from methanol would be investigated to lower the carbon footprint in methanol plants producing added-value chemicals.

The DECADE project concept is summarized in Figure 1.

Figure 1 DECADE project concept
The project is at the stage of the first reporting period (M1-M18). This period coincides with the most crucial period related to the pandemic situation and has been consequently strongly affected from this general situations which limited the possibilities of recruitment, travel and dissemination activities, but also caused delays in procurement activities.

During this period, the WPs active were those from WP1 to WP3, in addition to WP8 (coordination, management) and WP9 (ethic aspects). For WP4-WP5 and WP7 only minor activities were scheduled, while WP6 is planned for the final part of the project.

In WP1 (Specifications) studies on (i) the definition of benchmark business cases and (ii) the definition of the boundary conditions for the photoelectrochemical (PV-EC) cell were prepared. These reports represent a step forward from the general concepts reported in the DECADE proposal and a starting point for the detailed assessment of the proposed technological path in comparison with the state-of-the-art technologies/strategies.

WP2 (Electrode Design) was significantly affected from pandemic situation and thus non-yet-optimized anodes have been fabricated and tested with a fruitful collaboration between different partners. A list of materials has been identified based on their catalytic activity. A set of cathodic catalysts have been also synthesized and their activity confirmed. A set of plausible electrocatalysts have been identified and a few possible optimal working conditions have been proposed.

WP3 (PEC Design) has two objectives, the development of the PV component and the design of the cell. A multijunction Si based solar cells and modules were developed. The design and engineering of integrated PEC cell was also realized.
The activities in the other WPs, for which minor activities were planned, although in part anticipated, are in line with planning.

In WP4 (Assessment and exploitation) the activities related to each task (techno-economic analysis, LCA/LCC, environmental, market and social) have been started.

In WP5 (Scale up & Prototype) the PV module has been designed as well as the specifications of the system to start the engineering design of the prototype.

In WP7 (Benchmarking) initial benchmarking data and results were reported.

Finally, all activities related to WP8 (Project coordination and management) and WP9 (Ethics Requirements) are in progress as scheduled, although dissemination activities were strongly affected by the pandemic situation.
DECADE project goes beyond the state-of-the-art, proposing a novel solution to overcome limitations in current, state-of-the-art PEC approaches. In addition to solve PEC limitations, the substitution of water as preferred electron and proton reservoir is also adding commercial value to the process. Instead of oxygen, the anodic reaction participates to the final product, increasing the commercial interest, but also the energy efficiency. Currently, most PEC strategies only contemplate water as sacrificial electron and proton donor, with no clear or convenient alternatives. Alternatives, such as chlorine production, would be very difficult to implement due to safety issues, particularly for distributed solutions.

There are several elements of innovation in the proposed DECADE approach, based on the identification of the critical issues in the current PEC approach. Further relevant advantages are:
- Integration of solar energy within (bio)refineries, combined with the reuse of CO2 emissions to converge on the production of high added-value chemicals (circular economy). We will test in our prototype the use of conventional refinery CO2 streams to lower carbon footprint and improve circular economy, evaluating also the use for biorefinery streams. Thus, there is a win-win solution of integrating renewable energy in (bio)refinery while lowering the carbon footprint and increasing the production of higher value products.
- Development of circular economy and low-carbon production concepts for large-scale chemical processes, with the analysis of the integration of the novel PEC solution into methanol plants to convert waste CO2 to chemicals and introduce solar energy within the methanol value chain.
- A step to the distributed production of chemicals, particularly green solvents and fuel additives for gasoline, which can be produced in a single integrated device with minimization of downstream separation costs.
- The flexible use of the products to either green chemicals or high-octane number fuel additives, with analysis of different cases of applications and with the involvement of companies addressing different possible uses of the technology.

DECADE project will reduce the environmental impact on society of energy/chemicals production (reducing its CO2 footprint and use of resources) by i) enabling a change from fossil based to advanced use of bio-based products (including their associated CO2 emissions) in combination with direct solar energy, ii) developing new routes for utilization waste CO2 produced in chemical processes, iii) offering new opportunities to implement concept of circular economy and iv) new possibilities for distributed production of green solvents at local/regional level, with thus also positive impact on territory and local economies.
DECADE project logo
Figure 1 - DECADE project concept