Study On The Normalization Of Activated Carbon Surface Structure And Functional Groups

Activated carbon in gas selective adsorption has broad prospect of application, itssurface structure and functional groups have an important impact on its selectiveabsorption function, in order to do a better study on the correlation between the surfacefunctional groups and its selective absorption function, this paper developed a series ofspecial activated carbon, as a basis for further study on selective adsorption applications.The main research content were: used the commercially available spherical activatedcarbon（SAC） as a modified base, did a research on the surface acid, base, reduction andoxidation modification; used the market abandoned walnut shells as raw materials for theexperimental study of homemade walnut shell activated carbon; used variousmeasurement methods including N2adsorption, Boemh titration, Roman and DRIFTS tocharacterized the physical and chemical properties of the activated carbon obtained; usedthe main components of biomass syngas（CH₄and CO₂） as the target gas, studied theexperiment of the adsorption selectivity application. The main results were as follows:（1） The activated carbon with similar pore structure but had different surfacefunctional groups could be obtained through appropriate modification method. Theoxidation modification could make activated carbon almost did not contain any basicfunctional groups on the surface. Base modification and reduction modification couldmake basic functional groups on activated carbon become more than50%of thefunctional groups.（2） Surface modification could improve the graphitization degree of activated carbonand the reason might be that modified process eliminated the impurities in the activatedcarbon.（3） Homemade walnut shell activated carbon experimental study found that, withwalnut shell as raw material, through the choice of activator, control impregnatedconcentration, activation temperature, shell-base ratio and some other activation processcould prepare series of different pole structure walnut-shell-based activated carbon, thespecific surface area distributed from219m²/g to2180m²/g and microporosity were from40%up to92.5%. Among them, the specific surface area of the highest activated carbon preparation conditions were:10%phosphoric acid dipping, activation temperature of400℃, activation time of1h.（4） The selectivity of activated carbon adsorption experimental study found that theactivated carbon prepared by oxidation modification and phosphoric acid activation hadbetter selectivity for adsorption of CO₂than others. The surface functional groups and porestructure of activated carbon both had influence on its selectivity adsorption. Activatedcarbon containing small pore size and lots of microporous structure were moreadvantageous to the selection of CO₂adsorption.