Diffusion Coefficients of N₂O and H₂ in Water at Temperatures between 298.15 and 423.15 K with Pressures up to 30 MPa

Abstract

The diffusion coefficients of CO 2 and H 2 in aqueous solutions are important in numerous processes including carbon capture, geological carbon storage, and reservoir storage of hydrogen. As CO 2 is reactive in some aqueous solutions, especially aqueous amine solvents for carbon capture, N 2 O is frequently studied as a surrogate. In this work, the Taylor dispersion technique was used to determine the diffusion coefficients of N 2 O and H 2 at high dilution in water at temperatures between 298.15 and 423.15 K and at pressures up to 30 MPa, with a standard relative uncertainty of 1.6%. The new data are intended to resolve significant discrepancies in the literature. The results confirm that temperature is the most important controlling factor and that the diffusion coefficients are nearly independent of pressure in the region studied. The experimental data were correlated using the Stokes−Einstein equation, with average absolute relative deviations of 0.5% for both systems.