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Étude de procédés de conversion de biomasse en eau supercritique pour l'obtention d'hydrogène. Application au glucose, glycérol et bio-glycérol

Abstract : Supercritical water (T > 374 ° C and P > 22.1 MPa) gasification of wet biomass for hydrogen production is investigated. This process converts a renewable resource into a gas, which is mainly composed of hydrogen and hydrocarbons with interesting energy potential, and which can be separated at high pressure. In addition, the greenhouse gas effect of the process is zero or negative. Model biomasses (glucose, glycerol and their mixture) and bio-glycerol, residue from bio-diesel production, have been gasified by different processes: two-scale batch reactors (5 mL and 500 mL) and a continuous gasification system. Supercritical water acts as a reactive solvent, its properties can be adjusted by the choice of the experimental (P, T) couple. The operating parameters, e.g. temperature, pressure, concentration of biomass and alkaline catalysts, reaction time... allow favoring certain reaction mechanisms. In order to characterize the processes, specific analytical protocols have been developed and validated. The intermediates, formed during the heating time in the batch reactors, have been identified. Among the investigated operating parameters, temperature and reaction time have the greatest influence on the hydrogen production in batch reactors. In the presence of catalyst (K2CO3), H2 yields of 1.5 mol/mol glucose and 2 mol/mol glycerol have been respectively observed. The obtained gas contains different proportions of light hydrocarbons and CO2. About 75% of the carbon is converted into gas and liquid (in form of organic and inorganic carbon). The conversion leads also to a solid or oily residue. In the generated solid phase (composed over 90% of C), spherical nanoparticles are observed via electronic microscopy. The hydrogen production from glycerol is improved in the continuous process compared to batch reactors, however, bio-glycerol supercritical water gasification requests process improvement due to the precipitation of the salt contained in the reactant. In conclusion, supercritical water gasification of biomass can be considered as an promising alternative process for hydrogen production. The process should be improved by more performing equipments and by the control of the salinity content of the crude biomass.
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https://tel.archives-ouvertes.fr/tel-00690467
Contributor : Qian Michelle Yu-Wu Connect in order to contact the contributor
Submitted on : Monday, April 23, 2012 - 3:48:23 PM
Last modification on : Friday, August 5, 2022 - 11:43:39 AM
Long-term archiving on: : Tuesday, July 24, 2012 - 2:33:04 AM

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  • HAL Id : tel-00690467, version 1

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Qian Michelle Q. M. Yu-Wu. Étude de procédés de conversion de biomasse en eau supercritique pour l'obtention d'hydrogène. Application au glucose, glycérol et bio-glycérol. Génie chimique. Institut National Polytechnique de Toulouse - INPT; Université de Toulouse, 2012. Français. ⟨NNT : ⟩. ⟨tel-00690467⟩

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