A spectroscopic study of ternary gas diffusion

The unsteady diffusion of the ternary gas mixture CH 4 ( alpha ) - CO 2 ( beta ) - C 3 H 8 ( gamma ) is measured with FTIR Spectroscopy in the transmission mode at 308.15 K, 0.1 MPa and equilibrium compositions x alpha , infinity = 0 .333 and x beta , infinity = 0 .363. A parallel is drawn between the experimental approach and the classical Two- Bulb method. The geometry of the setup is calibrated by measuring the equimolar counter-diffusion of C 3 H 8 /CO 2 at 308.15 K and 0.1 MPa. Then, analogous experiments are conducted for the gas pairs CH 4 /CO 2 , CH 4 /C 2 H 6 , CH 4 /C 3 H 8 and C 2 H 6 /C 3 H 8 to measure their mutual diffusivity. Last, the ternary diffusion of CH 4 ( alpha ) - CO 2 ( beta ) - C 3 H 8 ( gamma ) is measured and modelled with the Maxwell - Stefan theory of multicomponent equimolar diffusion for ideal gas mixtures. Osmotic, reverse and barrier diffusion are observed and predicted for methane before reaching equilibrium