Scientific direction Development of key enabling technologies
Transfer of knowledge to industry

PhD : selection by topics

Engineering science >> Chemistry
2 proposition(s).

Development of metal components by stereolithography - Copper for energy application

Département des Technologies des NanoMatériaux (LITEN)

Laboratoire Recyclage et Valorisation des Matériaux

01-09-2019

SL-DRT-19-0751

marilyne.roumanie@cea.fr

Stereolithography (SLA) is a well-known additive manufacturing process based on photopolymerisation reaction. Specifically, metal SLA is based on the blend of a photocurable resin with a metallic powder. In this process, the polymer gives mechanical strength to the part during the manufacturing step. The polymer is then thermally removed (debinding step), and the parts is sintered. This process has the benefit of addressing a large number of materials, relying on the expertise of the powder metallurgy in terms of debinding /sintering and being easily implemented in this industrial field. Copper is known for energy application by their high thermal (385 W/m.K) and electrical (59.6 x 106 S.m-1) properties. The objective is to control the impact of the stereolithography process (formulation, light/matter interaction, thermal treatment) on thermal and electrical properties of bulk and structured copper components. The impact of the formulation on the cross-linking rate and the green mechanical strength, the relation between the cross-linking rate and the filled resin degradation on the cracking during the thermal step, and the relation between the thermal and electrical properties of the copper components and the microstructure, the density and the light elements contamination should be investigated during the PhD.

Biocrude production through hydrothermal liquefaction of micro-algae : study of the biochemical composition of algal biomass on biocrude quality and interest for biofuel production

Département Thermique Biomasse et Hydrogène (LITEN)

Laboratoire de ThermoConversion de la Bioressource

01-09-2019

SL-DRT-19-0826

anne.roubaud@cea.fr

Among the various processes which can be applied to convert micro-algal biomass into biofuels precursors, hydrothermal liquefaction (HTL) is regarded as a highly promising technology for treating a wide variety of biomasses (or biomass wastes) and obtaining valuable products, such as bio-crude. Compared to conventional approaches based on dry extraction and transesterification of algal lipids to produce biodiesel, HTL allows avoiding energy-intensive thermal drying of the biomass. HTL is using the unique properties of water in subcritical conditions. In those conditions, water is a solvent but also a reactant for the conversion of biomass. Algae biomass is made of different kinds of natural polymers (lipids, proteins, carbohydrates). Under hydrothermal conditions (250-350°C; 10-20 MPa, those compounds are converted through depolymerization and successive dehydration reactions, and also deamination and decarboxylation reactions. All those transformations lead to the reduction of oxygen and nitrogen in the final product, a kind of green bio-crude, compared to the initial biomass. The precise mechanism for this conversion is still not well known. A first work of this kind have been done at CEA for agro-industrial residues. The composition of the bio-crude obtained from HTL conversion is strongly dependent to the conversion of lipids, proteins, carbohydrates and other organic molecules originally contained in the biomass and thus vary greatly according to the nature of the micro-alga. The objective of this phD work is then to determine the relationship between the algal biochemical composition and the biocrude composition in order to optimise the biocrude adaptation for a future use as biofuel after a catalytic upgrading. This will include selection of the best process parameters, the establishment of a chemical conversion mechanism for a full comprehension of the transformation but also the selection of the best algae specie and cultivation conditions as the biochemical is influenced by both parameters. In this objective, HTL conversion of well calibrated algal biomasses will be studied. This work will be done using the experimental equipment of the laboratory, in batch reactor or with the continuous pilot. It will also need an important analytical work to characterize and identify the different products of the reaction. A simulation of the hydrothermal conversion will be needed to test the chemical mechanism and to seek for the optimisation of the process. This phD work will be done in collaboration with the Rafbioalg ANR project partners, in particular IRCELYON involved in the catalytic up-grading of the bio oil and CEA DPACA for the selection, characterization and cultivation of the micro-algae.

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