Self diffusion coefficients of organic solvents and their binary mixtures with CO2 in silica alcogels at pressures up to 6 MPa derived by NMR pulsed gradient spin echo

摘要: Abstract Self diffusion coefficients were determined using NMR (nuclear magnetic resonance) pulsed gradient spin echo (PGSE) in combination with a special high pressure autoclave. The goal was to determine the self for different CO 2 /methanol and /ethanol mixtures within pore phase of silica alcogels at pressures up 6 MPa. These values are required as input data modeling process steps preceding supercritical drying these gels. derived set-up 15 °C unconfined function concentration organic solvent well fluid line results from previous publications thus proofing approach provide reliable data. Measurements methanol methanol/CO ratios performed tetramethoxysilane based target densities ranging 80 200 kg/m 3 ; reveal tortuosities 2.5 depending on fraction gel its structure. experimental good agreement transport coefficient time resolved imaging exchange alcogel 5.8 MPa.