Equilibrium and transport properties of CO2+N2O and CO2+NO mixtures: Molecular simulation and equation of state modelling study

• Published in: Fluid phase equilibria 2012-05, Vol.322-323, p.66-78
• Main Authors: Lachet, V., Creton, B., de Bruin, T., Bourasseau, E., Desbiens, N., Wilhelmsen, Ø., Hammer, M.
• Format: Article
• Language: English
• Subjects: CO2 capture and storage; Environmental Engineering; Environmental Sciences; Equation of state; Molecular simulation; Viscosity; VLE data
• ISSN: 0378-3812; 1879-0224
• DOI: 10.1016/j.fluid.2012.03.011

► We provide new force fields to model N2O, NO and N2O2 molecules. ► We perform combined reaction ensemble Monte Carlo and Gibbs ensemble Monte Carlo simulations. ► We propose new pseudo-experimental data for the CO2+NO binary mixture. ► We calculate, using Molecular Dynamics, densities and viscosities of CO2 contaminated by N2O or NO. ► We calibrate binary interaction parameters required in standard cubic equations of states. In the present study, the thermodynamic behaviour and transport properties of CO2+N2O and CO2+NO mixtures have been investigated using molecular simulation and equation of state modelling. Molecular simulations were based on Monte Carlo and Molecular Dynamics calculations using force fields calibrated from pure component properties and no adjustment of mixture properties was performed. Original force fields were proposed for N2O, NO and N2O2 molecules. Special attention must be paid when studying nitric oxide containing systems because this compound can exist as a mixture of monomers (NO) and dimers (N2O2) under certain pressure and temperature conditions. Liquid–vapour coexistence properties of the reacting NO–N2O2 system were thus first investigated using combined reaction ensemble and Gibbs ensemble Monte Carlo methods. Using the new force fields proposed, phase compositions, phase densities and phase viscosities were determined for CO2+NOx mixtures. Due to the strong similarities between carbon dioxide and nitrous oxide (Tc(CO2)=304.21K; Tc(N2O)=309.57K; Pc(CO2)=7.38MPa; Pc(N2O)=7.24MPa), the obtained thermodynamic and transport properties for a CO2+N2O mixture with 10mol% of N2O are similar to pure CO2 properties in the whole range of studied temperatures (273–293K), in agreement with available experimental data. Calculations of CO2+NO equilibrium and transport properties were also performed at three different temperatures in the range of 253–273K. At these temperatures, only the monomer form of the nitric oxide (NO) has to be accounted for. The performed calculations are pure predictions since no experimental data are available in the open literature for this system. For a mixture containing 10mol% of NO, the simulation results show a decrease of the liquid densities and viscosities of 9% and 24% with respect to corresponding pure CO2 values, respectively. The new pseudo-experimental data generated in this work were finally used to calibrate binary interaction parameters required in standard cubic equations of states. Both Peng