Plasma group researches deal with the development of thermal and non-thermal plasma processes for energy and environmental issues. These researches are presently structured in the frame of two out of three CEP research themes: Energy, Processes and Environment and Nanomaterials and Energy.

Theme 1: Energy, Processes and Environment

The research concerns the conversion , more particularly the decarbonization of hydrocarbons both fossil (oil, natural gas, coal) and renewable (biomass, wastes), and their rational use in the present context of resources depletion and the greenhouse gases emissions limitations.

Main current actions are:

Plasma assisted hydrocarbon reforming for on-board hydrogen production oriented towards PEM applications and NOx and soot particles removing;
Plasma assisted hydrocarbons decarbonization for the co synthesis of carbon nanostructures and hydrogen.
Lignocellulose biomass gasification for second-generation synthetic biofuel synthesis;
Gas To Liquids conversion.

Theme 3: Nanomaterials and Energy

The research concerns the development of innovative processes for gas-phase nanoparticles synthesis oriented towards energy related applications (electrochemistry, photo catalysis…). Two families of nanomaterials are currently under focues:

Carbon nanomaterials (carbon blacks, fullerenes, nanotubes…)
Titanium dioxide (TiO₂)

Experimental researches lead to the development of adapted technological solutions using thermal and non-thermal plasmas as well as advanced analysis methods and diagnostic tools (pyrometer, optical emission spectroscopy, IR spectroscopy).

Theoretical researches are focused on the development of basic knowledge in the following topics:

Fluid mechanics and mass and heat transfers in industrials plasmas;
Plasma – particle interaction, influence on radiation heat transfers;
Thermodynamic and chemical kinetics of hydrocarbons in plasmas media either anaerobic (thermal decomposition) or oxidant atmospheres (reforming, plasma – assisted combustion);
Growth of nanoparticles in gas-phase synthesis processes.

Plasma assisted reforming

Etanol refroming under ATR conditions.

Researches in this field concern the reforming of hydrocarbons (gasoline, diesel, ethanol, E85) assisted by non-thermal plasmas. Reasearches aim at exploiting the potential of non-thermal plasmas under partial combustion (POx), steam reforming (SR) or auto thermal reforming (ATR). Targeted applications relate fuel cells feeding for on-boarding applications as well as exhaust gases cleaning up (NOx and soot particles).

High pressure electrical discharges

In the field of non-thermal plasmas, the term “high-pressure” generally refers to pressures ranging between 10 kPa and 100 kPa. For pressures higher than 1 MPa, the behaviour of low-current electrical discharges remains a poorly explored area. However, the study and the control of such discharges can open new prospects in many application fields such as: chemistry, lighting, or material synthesis...

In such non-thermal plasmas the high-energy electrons come into collision with gaseous molecules, leading to very active species including radicals, ionized and excited species, without heating the gas. These species can accelerate or enhance chemical reactions at temperatures close to room’s temperature. In parallel, high pressure conditions could potentially promotes chemical reactions such as hydrocarbons chain growth (gas to liquid conversion, fluorocarbon chemistry,…)

reacteur3D
3D representation of the very high pressure discharge reactor

Allothermal gasification of lignocellulosic biomass

First generation bio fuels have a limited potential (about 3 Mtep in France). The production of second-generation synthetic fuels from lignocellulose biomass is a mayor challenge given the available potential resource (about 25 Mtep in France).

Plasma biomass allothermal gasification represents a promising way for the production of second generation synthetic fuels (by means of Fisher – Tropsch or methanol synthesis). With respect to the auto thermal method, the allothermal approach enables to optimise the mass conversion and the CO₂ balance.

Current researches deal with an adavnced understanding of the biomass-plasma interaction, including thermochemical mechanisms and heat and mass transfers. The goal is to improve the conversion efficiency and to reach the profitability threshold at industrial scale in the near future.

Hydrocarbons decarbonisation for the co-synthesis of Hydrogen and Carbon Nanostructures (H₂ &CN)

Researches on this subject have been initiated in 1993. Initially oriented towards the co-synthesis of carbon black and hydrogen by thermal decomposition of hydrocarbons at very high temperature, researches have been diversified towards the synthesis of fullerenes and carbon nanotubes and the development of original low energy-consuming non-thermal plasma processes.

Current researches deal with the lowering of cracking energy together with the development of tailor-made nanomaterials for energy conversion applications, particularly in primary and secondary batteries, conducting polymers, gas storage.

Wrapping paper type carbon nanostructures obtained by non-therma plasma

Fullerenes synthesis

Discovered in 1985 by Kroto, Curl and Smalley (*), Fullerenes represent a new family of pure carbon molecules. With this discovery a new carbon chemistry chapter was open together with a new fascinating research field ! C₆₀ and other fullerenes molecules opening the way towards a multitude of potential applications in many applicative fields such as: energy, optoelectronics, chemistry, drugs, medicine, cosmetics,…

Researches on the development of a new process for the bulk production of fullerenes started at CEP in the 90’s . These researches, initiated in the frame of two EC projects, were followed in the frame of a collaboration with TIMCAL.

The process is based on the vaporization-condensation of pure carbon particles in an helium plasma. Several international patents have accompanied the development of the plasma technology.

By opposition with combustion based processes, the plasma process is energy efficient and totally environmentally friendly.

A new particularly promising emerging application field of fullerenes is related to organic solar cells based on bulk heterojunctions of conductive polymers and fullerenes derivatives (P3HT / PCBM).

(*)1996 Nobel Price awarders in Chemistry

Synthesis and thermal treatment of TiO₂ particles by non-thermal plasma

Researches on this topic were initiated in 2007 with a targeted application related to the photocatalytic hydrogen production. Two approaches are currently under investigation: gas-phase synthesis of TiO2 (anatase) and surface treatment of nanoparticles by non-thermal plasmas (N2 doping).

tio2

Experimental set up: (a) Scheme, (b) Non thermal N₂ plasma plume (without particles) (c) with particles during the Nitrogen plasma treatment

Two approaches are currently under investigation: Gas-phase synthesis of anatase TiO₂ (anatase) by plasma-assisted combustion techniques and the surface treatment of nanoparticles by non-thermal plasmas.

For more information, please contact Laurent FULCHERI (Head of the plasma group).

Equipment