Chemical sciences

La réduction photocatalytique du CO2 en « carburants solaires C1/C2 » est une réaction de conversion attrayante car elle présente l’avantage d’éliminer ce gaz à effet de serre tout en fournissant un produit valorisable. Cependant jusqu’à aujourd’hui, malgré les nombreux efforts déployés, le niveau de conversion du CO2 reste très faible, même pour les catalyseurs les plus actifs du marché et un manque de compréhension perdure quant aux mécanismes réactionnels à l’œuvre. Afin d’apporter une réponse à ce dernier point, ce travail de thèse a porté sur l’étude d’un système photocatalytique modèle de type Pt/TiO2 et a déployé pour cela, au sein d’un photoréacteur, une méthodologie operando couplant plusieurs techniques...

Heterogeneous catalysts are materials that make chemically possible and economically viable countless industrial processes in the service of energy-related and environmental problems, such as fuel production and air quality (vehicle emissions, building interiors). Their implementation involves two major scientific challenges: (1) the identification of the chemical, structural and morphological properties of an optimal catalyst , (2) the evolution of these properties over the catalyst’s life-cycle (synthesis, preparation, use, recycling)...

Driven by the global challenge of switching to a more sustainable economic and energy model, IFPEN has been studying for a number of years biosourced products with high added value and working to develop processes for biomass recovery, as an alternative to conventional petrochemistry.

Although the climate crisis makes the reduction of CO2 emissions a matter of urgency, some industries will have difficulty in avoiding them, such as cement plants (where the core process is currently based on the calcination of CaCO3) or refineries, which are currently highly energy-intensive. Hence the huge potential interest in procedures that could capture the CO2 released directly from the plant (...) then recover it at a fraction of the energy cost...

Faced with the current climate challenges, alternative fuels are attracting a growing interest for the mobility of the future. Of the various possible alternatives, hydrocarbons could be synthesised via a well-known process: the Fischer-Tropsch (FT) process, based on Syngas (CO and H2) produced, in particular, by biomass gasification. (...) However, the deactivation of FT catalysts is a major issue that directly impacts the costs of the process. (...) To identify these mechanisms, a multiple-stage methodology was implemented as part of a doctoral thesis...

The production of biofuels, renewable diesel or sustainable aviation fuel can be achieved through lipid feedstocks conversion, such as vegetable oils, used cooking oils or animal fats. Through a hydrotreatment stage, we obtain long-chain normal paraffinsa, which must then be isomerised or cracked in order to adjust the properties of the effluent, resulting in the specifications required according to the targeted fuel type (particularly cold flow properties and/or final distillation temperature)...

Zeolites are microporous crystalline aluminosilicates that exist in the natural state and can also be synthesised for a wide range of applications, from the biomedical industry to the production of renewable energy. (...) This work was carried out entirely at IFPEN as part of a doctoral thesis and has resulted in a new stable zeolite...

Chemical theory at quantum level (density functional theory or DFT) is an essential tool in rationalising the reaction mechanisms involved in the preparation of catalysts, as well as in their use, thanks to the optimisation of their activity [1,2]. IFPEN has carried out a number of projects aiming to shed light on these catalysts, which are of particular interest to industrial processes...