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2018-10-12 - Travail avec promoteur/Doctorat - Anglais - 239 page(s)

Meunier Nicolas, "Catalytic Conversion of CO2 coming from Cement Kilns Flue Gases into Methanol: Optimization of the Overall Process", soutenue le 2018-10-12

  • Codes CREF : Traitement des effluents gazeux (DI3843), Technologie de l'environnement, contrôle de la pollution (DI3841), Thermodynamique chimique (DI132C), Génie chimique (DI2721), Chimie (DI1300)
  • Unités de recherche UMONS : Génie des Procédés chimiques et biochimiques (F505), Thermodynamique, Physique mathématique (F506)
  • Instituts UMONS : Institut de Recherche en Energétique (Energie)

Abstract(s) :

(Anglais) This PhD thesis focuses on the reduction of the CO2 anthropogenic emissions coming from the cement sector by investigating its possible conversion into methanol. To this extent, a preliminary study has been performed to introduce the cement manufacturing process and define the flue gas exiting the cement kilns that will be considered as raw material of the CO2 purification process. In this perspective, the conventional purification technologies (such as dust, SOx and NOx removal techniques) and the CO2 capture and purification technologies that are applied to industrial flue gases have been summarised. The wide panel of Carbon Capture and Reuse or Storage (CCUS) technologies has been presented and the CO2 conversion into methanol has been selected as one of the most promising CCU technologies. As a result, the thermodynamic study of the hydrogenation of CO2 into methanol has been presented through several sensitivity analyses because this reaction is highly thermodynamically limited. This thermodynamic study was completed by a literature review regarding the catalysts to be used and their related kinetic mechanisms, models and deactivation phenomena. A kinetic study is also proposed on a commercial CuO/ZnO/Al2O3 catalyst and on an innovative homemade CuO/ZnO/ZrO2 specially designed with the collaboration of the European School of Chemistry, Polymers and Materials of Strasbourg, for the conversion of pure CO2 into methanol. The experiments were conducted on a homemade-designed micro-pilot installation, allowing the determination of the kinetic constants of the kinetic models selected to describe both these catalysts. The entire CO2 conversion chain from its capture to its conversion into methanol was also investigated. In this perspective, the CO2 conversion process has been optimized with regards to the operating conditions and considering internal and external integrations. Finally, the integrated and optimised process, scaled to treat the emissions of a cement plant equipped with the Best Available Technologies, is able to treat 2475 tonnes per day CO2 and convert 90% of them into 1546 tonnes methanol per day. The heat integration inside the conversion unit reduces the reboiler duty required for the distillation of the water-methanol mixture by 100%. The heat integration between the CO2 capture and conversion units also reduces the reboiler duty required for the regeneration of the solvent by 32.7%. The water integration from the coproduct of the methanol synthesis completely fulfils the water demand of the CO2 capture unit for water make-up. The LCA also emphasises the high potential of this alternative route compared to the conventional production of methanol from steam methane reforming due to the reduction of the dedicated CO2 emissions by over 50%. Finally, the proposed CO2-based conversion process can be considered as a very good substitution alternative for methanol production and a solution for climate change mitigation. However, its economic breakthrough is strongly related to the costs of the electricity required for the production of hydrogen.