关键词: 沼气提纯, 变压吸附, 脱碳, 碳分子筛, 甲烷

Abstract: Carbon molecular sieves were selected to separate CH₄/CO₂ mixture by pressure swing adsorption. Adsorption isotherms of pure CH₄,CO₂ and N₂ gases on carbon molecular sieves were measured by the intelligent gravimetric analyzer apparatus(IGA-100,HIDEN)at 25℃,and the gas diffusion rates on the adsorbents were in the order of CO₂>N₂>CH₄. The breakthrough curves were measured by single fixed bed device. Pressures,flow rates and trace nitrogen(2%)were discussed to investigate separation performances,and adsorption mechanisms were also discussed. The results indicated that adsorption capacity of CO₂ and CH₄ on carbon molecular sieves were 35.9mL/g and 5.4mL/g respectively at pressure of 0.4MPa and flow rate of 200mL/min. The separation coefficient of CO₂/CH₄ reached 12.6,indicating that pure CH₄ could be collected from the fixed bed device,and the carbon molecular sieves could be well regenerated by vacuum desorption. These results suggested that carbon molecular sieves might be suitable for CO₂ removal from biogas. The diffusion rate of N₂ was faster than that of CH₄ on carbon molecular sieves; therefore it is possible to enrich CH₄ with high concentration through the fixed bed device.

Key words: biogas purification, pressure swing adsorption, decarbonization, carbon molecular sieve, methane