Competitive Adsorption Equilibrium Isotherms of CO, CO2, CH4, and H2 on Activated Carbon and Zeolite 5A for Hydrogen Purification

Adsorptive separation techniques such as pressure swing adsorption can be employed on a large scale to separate and purify hydrogen. The streams of hydrogen are multicomponent mixtures of H-2, CO2, CO, and CH4. Competitive isotherms of adsorption of a multicomponent gas mixture (CO2, CO, CH4, and H-2) on two commercial sorbents (activated carbon and SA zeolite granules) are presented in this work. Adsorption equilibrium is investigated in a wide range of pressure (1 to 18 bar) at three temperatures (25, 35, and 45 degrees C). A study has been performed on the loading ratio correlation and Langmuir models for the adsorption. The adsorption capacity of different components of the gas mixture on activated carbon follows the order CO2 > CH4 > CO > H-2, and the adsorption capacity order for the zeolite is CO2 > CO > CH4 > H-2. The loading amount of carbon dioxide on zeolite SA increases quickly at low pressure, and disruption at these pressures is hard. Hence, carbon dioxide should not reach into the zeolite layer. For activated carbon, the Langmuir model fit the data with fairly good accuracy within the operating conditions studied. Both models were able to fit the experimental data for zeolite SA with good accuracy.