Chemical sciences

Contribution of chemical imaging by X-ray Absorption Spectroscopy for localized monitoring of the impregnation and activation of heterogeneous catalysts

In order to reduce the energy consumption of catalytic processes, one of the levers is to optimize catalysts. This optimization is accompanied by an ever-increasing need to characterize these solids. This is particularly the case for hydrotreating catalysts that produce fuels and chemical intermediates with low environmental impact.

Molecular simulations applied to lithium batteries

Background: In the light of sustainable mobility, batteries play an essential role in the electrification and hybridization of transport vehicles. Batteries based on lithium ions currently offers one of the best performances with respect to other rechargeable batteries. However, in lithium ions batteries solid electrolyte interphase (SEI) layers are formed that can severely impact the performance of these batteries if they use graphite-based electrodes.

Design of impact characterization factors adapted to the Life Cycle Assessment method for the evaluation of fuel emissions at altitude.

Renewable energies (RE) are the most suitable vectors to meet the imperatives of environmental protection and reduction of greenhouse gas emissions. The air transport sector is positioning itself on these new energies as part of its objective to stabilize CO2 emissions from 2020 onwards and then to reduce its CO2 emissions by 50% by 2050. However, the air transport sector is growing and it’s becoming a key issue to find sustainable solutions regarding the choice of fuels. Most of the air transport emissions occur at altitude during the aircraft's cruise phase.

Unravelling CO2 reduction mechanisms on the photocatalyst surface from operando approach

The use of solar energy to convert CO2 into hydrocarbons could mitigate two main problems : global warming and future energy demand. The photocatalytic route is pertinent, but the process yield remains low even for the most efficient developed materials and many questions stay opened regarding the intrinsic properties of the photocatalyst to be optimized and about the reactional mechanisms.

Zeolite based catalysts for alkyl-aromatics isomerization

The increase in the world population coupled with technological development will generate a growing demand for petrochemicals in the coming decades. This will contribute to the shift of the use of hydrocarbon resources to petrochemicals at the expense of fuels. Para-xylene is a molecule particularly sought after because it is involved in particular for the production of polyester fibers for clothing or resins. This molecule can be produced by isomerization reactions of other aromatic molecules of lower value. Heterogeneous catalysts are used to catalyze these reactions.

Machine learning to optimize ReaxFF parameters

Computer simulation tools are widely used at IFP (Energies nouvelles (IFPen) for applications in various fields of energy, transport and the environment. The use of multi-scale modeling has become a key factor for successful studies. In chemistry, molecular modeling contributes to the understanding of phenomena occurring from electronic to mesoscopic scales. The explicit consideration of chemical reactions in molecular simulations requires the use of a so-called "reactive" force field such as ReaxFF.

Exploring the effects of porosity and acidity of large pore zeolites on the transformation of sugars to platform chemicals

Mastering the conversion of biomass to useful chemicals (bioplastics, etc.) is one of the big challenges of our society. Two third of the annually produced biomass is carbohydrate biomass, i.e. sugar polymers. The depolymerisation of carbohydrates leads to glucose, fructose, xylose, etc. These molecules are highly functionalized and can be converted to a range of interesting products, for example, 5-hydroxymethylfurfural, which is the base of a new biopolymer that can substitute PET, levulinic acid, lactic acid, etc. 

Development of mild reduction routes to low-valent metal complexes for catalytic applications

The design of new active and selective catalysts is a crucial challenge in the current context of sustainable development and atom efficiency. In this sense, homogeneous catalysis based on the design of perfectly defined metallic precursors, is capable of reaching the needs for this purpose. The activation of these metal precursors under reaction conditions is a key step in the generation of highly selective single site catalysts.

Understanding and modelling the internal short circuit in Li-ion batteries

The electrochemical storage of electrical energy has become a global issue and a major challenge. Li-ion batteries are considered as the preferred solution to store energy on board of new generation electric and hybrid vehicles or manage renewable energy in stationary applications. Safe batteries systems still represent today the weakest link in the development of many energy or power demanding applications.

Molecular simulation of the genesis of supported Pt and PtSn catalytic active phases

Supported metallic catalysts are of paramount important in heterogeneous catalysis. In particular, PtSn/γ-Al2O3 systems, where the metals are in the form of sub-nanometric particles, are industrially used for the transformation of hydrocarbons and oxygenated molecules. They are classically obtained after a sequence of impregnation of the support by contacting with an aqueous solution of metallic complexes, followed by drying, calcination and reduction to form metallic clusters. Such synthesis procedure was optimized empirically.