Homogeneous and Heterogeneous Reactivity
Energy Environment
The “Homogeneous and Heterogeneous Reactivity” theme focuses on the following scientific question:
What are the basic transformation processes of gaseous and particulate pollutants in the atmosphere?
The work is divided into two areas of research:
Area 1 – homogeneous reactivity – for a better understanding of the chemistry of trace gases: atmospheric radicals (e.g. OH, NO3, peroxyl radicals), inorganic compounds such as ozone and nitrogen oxides, and volatile organic compounds (VOCs), including biogenic VOCs (terpenes) and some oxygenated VOCs (alcohols, aldehydes, furans).
Area 2 – heterogeneous reactivity – also aims to improve our knowledge of the processes involved in the interactions of these species with atmospheric surfaces, including airborne particles (mineral and volcanic dust, inorganic and organic aerosols) and macroscopic surfaces.
The goal is therefore to set the kinetic parameters of elementary processes (rate coefficients and yields of chemical reaction products, capture coefficients on surfaces) and describe the transformation mechanisms in as much detail as possible. The purpose of this work is to propose a detailed description of the transformation processes of air pollutants which are useful for atmospheric chemistry models, in order to help optimise policies to improve air quality and combat climate change.
The scientific strategy implemented in this theme is based on an integrated approach to the two research areas mentioned above and an activity to develop experimental and metrological systems. This development activity is essential in order to provide the tools to (i) detect the transient species involved in transformation processes and (ii) monitor these processes on adapted time scales and under experimental conditions which are representative of the atmosphere (pressure, temperature, chemical matrix).
Transformation processes are studied both in the laboratory on simplified matrices, to identify and characterise the elementary steps, and in the field in real air masses, to account for potential interactions between transient species when many compounds are oxidised simultaneously. This dual approach provides an integrated and detailed view of atmospheric transformation processes.
Some examples of measurement tools and experimental devices developed at CERI EE are presented below. These devices are used in the laboratory (Thalamos thermoregulated simulation chamber, Knudsen reactor) and in the field (DouAir mobile simulation chamber (9 m3), ozone production rate measuring device).
Laboratory devices: Thalamos simulation chamber (left) for variable temperature studies of (i) gas phase kinetics and (ii) reactivity of macroscopic material emissions. Knudsen Reactor (right) for measuring gas capture coefficients on surfaces.
Field devices: DouAir mobile simulation chamber (left) can be used (1) in the laboratory for gas phase kinetic studies with simplified atmospheres and (2) in the field to monitor the ageing of a mass of air trapped inside the enclosure.
Ozone Production Rate Measurement Tool (right) – OPR – developed to study the formation chemistry of tropospheric ozone.
PROJECTS
Labex CaPPA
Labex CaPPA
Laboratory of Excellence on “Chemical and Physical Properties of Aerosols” (Labex CaPPA) The CaPPA laboratory of excellence won the second wave of the “Laboratories of Excellence” call for projects (2012) of the French Investments for the Future Program (PIA). It…
UNREAL
UNREAL
The UNREAL Project: Unveiling Nucleation mechanism in aiRcraft Engine exhAust and its Link with fuel composition (UNREAL) The UNREAL project aims to conduct molecular level studies on the various new particle formation mechanisms in engine exhaust from aircraft using different…
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