PhD IfP France

Amine characterization using molecular simulation

Location : University of Tarragona (Spain)

Promoter : Veronique LACHET

Apply : Veronique.LACHET@ifp.fr

Aqueous amines are commonly used in many industrial processes developed for the
treatment of natural gases. IFP has been working for several years in the development of
sweetening technologies to remove CO2, H2S and impurities, like COS, RSH and other
sulphur compounds, that are present in variable quantities in the natural gases. These
technologies are based on the absorption of these contaminants in chemical and/or
physical solvents. The accurate knowledge of phase equilibrium as well as phase
properties of the involved systems is essential for the sizing of the gas processing units. In
the proposed work, these required properties will be studied using molecular simulation
techniques. Equilibrium properties will be studied by Monte Carlo simulation, whereas
transport properties will be assessed using molecular dynamics.
The first step of the proposed work will be the development of an accurate transferable
intermolecular potential required to study thermo-physical properties of different amine
molecules. These developments will be done for standard primary, secondary and tertiary
amines, and also for more complex amines baring other polar groups like alkanolamines
(MEA, DEA, MDEA...). The different properties that will be studied during this work are
vapour pressures, heat capacities, densities, viscosities and critical coordinates.
Properties of new solvents developed in IFP projects could also be calculated using the
proposed potential for amines.
The second step of the proposed work will be devoted to the study of water-amine and
gas-water-amine mixture properties. This work program will imply substantial
methodological developments in order to accurately model the hydrogen bonding that
might occur between water and amine molecules and also to take into account some
possible chemical reactions in the system (protonation of amines for instance). A
generalization of the Reaction Ensemble recently implemented in the GIBBS simulation
code will be undertaken in order to extend its application to flexible molecules. Transport
properties of these mixtures will also be studied. Among others, the diffusion coefficients
of different gases (CH4, CO2, H2S, O2, N2, Ar...) in amine solvents will be calculated using
molecular dynamics.

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