Predicting the diffusivity of CO2 in substituted amines

Predicting the diffusivity of CO2 in substituted amines

Masy, E.

Balaji, S.P. (mentor)

Applied Sciences

Chemical Engineering

ETh

2013-03-15

The experimental determination of the diffusivity of carbon dioxide (CO2) in an amine solvent is difficult as the CO2 diffuses and reacts simultaneously when absorbed into an amine solvent. As the knowledge of the diffusivity and solubility of CO2 is essential to design the absorption units based on amine solvents, the nitrous oxide (N2O) analogy is used in practice to estimate them. It consists of evaluating those physical properties by substituting the reacting CO2 with an inert gas of a similar structure, N2O. The diffusion of CO2 in amine solvents is investigated using molecular dynamics (MD) simulation. Unlike experiments, MD simulation allows a direct measurement of the CO2 diffusivity. In MD simulations, the reaction between CO2 and the amine can be switched off. The Fick diffusion coeffcients are derived from the Maxwell-Stefan diffusivities and the thermodynamic factors. Different amine solvents like monoethanolamine, diethanolamine, methyl-diethanolamine and ethylamine are investigated. The N2O analogy in the monoethanolamine-water solution has been validated.

diffusion
amine
CO2 absorption
N2O analog
Maxwell-Stefan diffusivity
thermodynamic factor
molecular dynamic simulations

http://resolver.tudelft.nl/uuid:eb02394d-4321-47c1-b79c-086e393f7307

Student theses

master thesis

(c) 2013 Masy, E.