The Modification And Characterization Of Activated Carbons And The Application In Enriching Coal-Well Methane

Activated carbon was an important adsorbent and catalyst supporter. Due to its special porous texture and surface chemical property, it was widely used in many fields, such as adsorption and separation, energy storage, catalysis and environment. In those years, series of activated carbons, with advanced porosity, high surface area, and proper pore size distribution, have come into being and were named super activated carbons which were followed with a great progress in the preparation, characterization and application. Coal-Well-Methane (CWM) was another form of Natural Gas (NG) as an excellent fuel and industrial raw stuff. With the increase of the energy quantity and the environment-preserving concept, it grows to be a great importance to recover the CWM.The performance of activated carbon in enriching CWM was determined by the porous texture and surface chemical property. All activated carbon samples were modified by oxidization, heat treatment and surface modification, in order to change the porous texture and surface chemical property. It was showed that oxidization with HNO3 and H2O2 can introduce a great deal of acidic groups without the obvious change of porous texture. Heat treatment reduced large amount of acidic groups, such as carboxylic acid, lactone, carboxylic anhydride, phenol, carbonyl and ketone, made nitrogen-containing groups increase, and changed the porous structure greatly; Heated in the N2 atmosphere, acidic groups were removed and the porous structure was changed and great deal of nitrogen-containing groups were introduced.Pressure swing adsorption (PSA) process was usually used in the O2/N2 and N2/CH4 separation based on kinetic separation or thermal separation. In traditional PSA process, in order to maximize the concentration of the target-gas, the complex and optimized operational procedures which can cover the shortage of adsorbents, were determined. However, the purpose of the present work was to investigate the pore structure influence and get the optimum porous parameter. So, the traditional PSA process can't be used directly in our present work and it was necessary to design another apparatus and procedures to evaluate the AC samples. From evaluation results, it was found that high micropore surface area and pore volume was positive to the performance in enriching coal-well methane and the optimum pore size was in the range of 0.758~0.776nm for the greatest selectivity of methane in CH4/N2 mixture.