Report

Teaser, summary, work performed and final results

Periodic Reporting for period 2 - MONACAT (Magnetism and Optics for Nanoparticle Catalysis)

Teaser

The development of renewable energies is an essential requirement for a future sustainable world. Presently, most of the countries announce a development of both solar and wind power. However, both energies are intermittent and raise questions regarding their real efficiency...

Summary

The development of renewable energies is an essential requirement for a future sustainable world. Presently, most of the countries announce a development of both solar and wind power. However, both energies are intermittent and raise questions regarding their real efficiency since energy production can oscillate between shortage and over-production. The present solution to this problem is the use of the “smart grid” associated to a complex power management. The result is nevertheless a loss of ca.10% of the electrical energy produced in France (25 to 70 TWh). An interesting alternative would involve local electrical energy storage but it is costly and still displays a low efficiency. The power-to-gas approach is another alternative for which the first natural candidate would be hydrogen produced by water electrolysis but despite impressive progresses, its local storage, transport and massive use still presents safety, technology and cost issues. In light of these facts, the most relevant answer appears to be hydrocarbons since they display the largest energy density on a Ragone plot and could be used locally for heating and transport applications or be carried on long distances using existing systems.
The main route to prepare hydrocarbons from renewable sources of energy involves hydrogenation of CO or CO2, namely Fischer Tropsch Syntheses (FTS) and Sabatier processes respectively, using hydrogen produced by electrolysis for which mature solutions exist or by water splitting. Intermittent energy storage requires energetically efficient processes which could rapidly be started or stopped and which could be part of medium scale units distributed over the territory. This rules out present FTS plants which require a long time for warming up or cooling and complex separation processes. Methane could be an attractive target since it can indeed be produced selectively by hydrogenation of CO2 and directly injected into existing gas pipes. Furthermore, the development of biogas production leads to mixtures of CO2 and methane which could be enriched upon hydrogenating the remaining CO2 rather than separating it. Methanol is another attractive target which has been proposed as a sustainable source of energy for fuel cells, and as a raw material for production of higher hydrocarbons. Production of methane or methanol raises however the question of the energy necessary for these reactions to proceed and of the time necessary to reach the working temperature. In this respect, an appealing and efficient solution would be to limit the heating to the catalytically active phase using a pertinent physical property..

MONACAT therefore proposes a novel approach to address the challenge of intermittent energy storage. Specifically, the purpose is to conceive and synthesize novel complex nano-objects displaying both physical and chemical properties that enable catalytic transformations with a fast and optimum energy conversion upon magnetic or optical excitation. In this respect, MONACAT is presently developing a process of magnetically induced CO2 hydrogenation for chemical storage of intermittent energies which is beeing developed at the pilot scale. Magnetically induced catalysis has further been applied to higher temperature reactions such as propane and methane dry reforming and propane dehydrogenation as well as in solution for biomass molecules transformations.

The new process of magnetically induced catalysis has two main advantages : i) the possibility to trigger a catalytic reaction within a time scale of a second. This is fully adapted to intermittent energies. ii) the energy efficiency, expected to be the highest for heating a ferromagnetic material. At the moment we are in the process of optimizing it for CO2 hydrogenation.

Overall, MONACAT results can give rise to energy efficient processes which can adopt various sizes from small ones adapted to a windmill or to a photovoltaic farm, up to large industrial units, for example

Work performed

ERC MONACAT project : Scientific Report

As stated in the proposal, the main purpose of the MONACAT project is to “couple the physical properties and the chemical properties of either the same nanoparticles, or of islands or layer of other metals deposited on their surface, to develop a novel approach of energy efficient and dynamic catalysis, the most interesting application and primary target of this process being the storage of intermittent energies”.

In this respect, the project was divided into 6 tasks which have now all started and, for some of them, which are almost completed. In addition, structural studies have been carried out for all tasks since the beginning of the project. The characterization aspects are transversal and included into the different tasks.

The first and main object of the proposal was the demonstration of the possibility of a catalysis induced by magnetic induction and leading, in a flow, to excellent productivity. This was the object of Task 1 and has already been achieved. A generalization of the process, and the transfer of the process to a pilot which was beyond the task expectations is now in progress. Task 2 has nevertheless been found to raise new questions regarding a larger variety of materials and their heating mechanisms. New and fundamental results have been obtained and new materials have been tested in conjunction with Task 5. Task 3 revealed to be very difficult and although significant progress has been achieved, we have chosen to increase the manpower in three aspects, chemical synthesis, physical chemistry and physics which led to new results both in the physical understanding of thermometry and the preparation of new non-toxic quantum dots. Task 4 was in the proposal aimed at further development of environmentally friendly catalysis. We have chosen to have a PhD thesis rather than a post-doc for the same budget since it was more a long term exploration. Nevertheless interesting results concerning plasmonic heating are appearing and one of them has already been published. Task 5 has now officially started both in finding new catalysts and in finding new heating materials. This concerns both the design of a practical and stable material for the pilot of Task 1 and playing on Curie Temperature by making FeCo and FeNi NPs. Task 6 is interesting since we had decided to stop it. However, one post-doc had a brilliant idea and we have found very interesting and unusual results which are presently leading to a rapid development of the field and the creation of new collaborations. In fact, we have proven the original idea that “overheating” was possible in solution to achieve unexpected reactions. The main goal being for biomass valorization.

In summary, we have made progresses much faster than expected concerning Task 1 which is in progress towards a pilot now. We have a lot of new developments concerning Tasks 2 and 3. Task 4 revealed to be complex but appears to be almost completed now. Task 5 is developing rapidly and Task 6 got a lot of success recently after having been considered as abandoned.

This work will be detailed here below.


Task 1 (Task 5): Monitoring and optimization of methanation at the surface of complex nanoparticles (1 PhD: Julien Marbaix, 1 post-doc shared with Task 6 Juan-Manuel Asensio)
The first purpose for the optimization of the methanation reaction was to have nanoparticles of reproducible heating power and catalytic capabilities. This has been achieved with iron carbide nanoparticles between 12 and 14 nm and displaying a heating power of either 1 or 2 kW/g (100 kHz, 46 mT) which are values of one order of magnitude higher than those obtained for the best iron oxides. A correlation has been established on one side between the intrinsic structural and magnetic properties of the particles and their heating power and on the other between their agglomeration state and their heating power, both leading to an optimization of the heating material.

Final results

\"The main purpose of the MONACAT project is to \"\"couple the physical properties and the chemical properties of either the same nanoparticles, or of islands or layer of other metals deposited on their surface, to develop a novel approach of energy efficient and dynamic catalysis, the most interesting application and primary target of this process being the storage of intermittent energies”.

In this respect significant results have already been obtained :

- CO2 hydrogenation into methane. The optimized process is beeing transferred to a pilot.
- Generalization of magnetically assisted heterogeneous catalysis playing on the Curie temperature of the heating materials. Access to high temperature reactions (propane and methane dry reforming, propane dehydrogenation)
- Temperature measurements on or near the surface of the nanocatalysts.
- Development of new quantum dots made of non toxic materials and showing high luminescence properties.
- Extension to catalysis in solution and applications to molecules derived from biomass.

Until the end of the project, MONACAT will develop the scope of catalysis in solution and work at the development of a process for other heterogeneously catalysed reactions such as methane dry reforming and methanol synthesis. In parallel, we will finalize the development of a magnetically induced process for CO2 hydrogenation for transfer to industry.




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