Temperature-Swing Separation of Hydrogen-Methane Mixture

Particles of a coal char (from Montana lignite) were used in a fixed bed for cyclic separation of a mixture of hydrogen and methane. The column was operated in the temperature cycling mode between 25 and 250 °C at a total pressure ranging from 21 to 34 atm. The methane concentration was enriched from 50% to over 90%, which was the goal of separation for production of high-Btu gas. It has been shown that the coal char is as effective as a commercial activated carbon being used as the sorbent. The experimental data showed that pore diffusion is important in separation. A simplified pore-diffusion model was developed which gave satisfactory predictions of the performance of temperature-swing separation. In the simplified model a parabolic Intraparticle concentration profile was assumed and the computation was further simplified by using a particle volume-averaging technique.