Preparation Of Granular Activated Carbon By CO₂-chemical Activation And Its Application In Pressure Swing Adsorption Separation For CH₄/N₂

The purification of CH₄ from extracetd coal-bed gas with low CH₄ concentration is of great significance for the environmental protection and energy conservation.Pressure swing adsorption?PSA?technology is suitable for separation of CH₄ from extracetd coal-bed gas in China.Granular activated carbon?GAC?is an adsorbent commonly used in PSA for the seperation of simulted coal-bed gas?CH₄/N₂?.In this thesis,the anthracite used as the raw material to prepare GAC by using CO₂-chemistry activation method.The effects of preparation conditions on the pore structure,pore size distribution,and surface properties of GAC,and the PSA separation performance for CH₄/N₂ were studied.The erxperimental results showed that CH₄ concentration degree of 30% was obtained when the the activated carbon prepared under optimum preparation conditions was used in PSA.The optimum preparation conditions of GAC are concuded as 600 °C of carbonization temperature,2.5h of carbonization time,10 °C/min of heating rate,1h of KOH?6%?activation time,950⁹60 °C of CO₂ activation temperature and 3h of CO₂ activation time.Pores around 5 ? and 5.36 ? are two main group pore sizes for the prepared activated carbons.The activated carbon surface contains more oxygen-containing functional groups and acidic groups which are conducive to the adsorption of methane.The adsorption selectivity fator for CH₄ over N₂ of the GAC prepared under optimum conditions was 3.6.