TErnary Gas Mixture Separation by Pressure Swing Adsorption: A Combined Hydrogen-Methane Separation and Acid Gas Removal Process

An experimental and theoretical study was conducted for the bulk separation of a ternary gas mixture by pressure swing adsorption. Each cycle encompassed four steps: pressurization, adsorption, cocurrent blowdown, and countercurrent vacuum desorption. The experimental data were satisfactorily predicted and simulated by an equilibrium model and a linear-driving-force model. A feed mixture containing 49.5/49.5/1.0 H₂/CH₄/H₂S was separated into three useful products: a clean H₂ (over 99% H₂ and below 0.01 % H₂S), a clean CH4 (over 95% CH₄ and below 0.01 % H|₂S), and an H₂S product (over 10%). Cocurrent blowdown was a crucial step for recovering the medium product (CH₄). Vacuum desorption and pressurization by H₂ were important in recovering the heavy product (H₂S) and cleaning the bed for a high-purity H₂ product. These and other fundamental principles for bulk separation of multicomponent mixtures by PSA were discussed.