Study Of Activated Carbon Materials For Enrichment And Separation Of Coal Mine Gas By PSA Process

IN this work, we carried out series of studies of adsorbents in the enrichment andseparation of coal gas, by using a variety of methods to modify or produce activatedcarbon and activated carbon fibers.First, the adsorption capacity of5kinds of ACFs for CH₄and N₂at298K wasmeasured. It shows that the adsorption capacity for CH₄is larger than N₂and theiradsorption capacity increases with increasing pressure and gradually tends to aconstant. Adsorption isotherms belong to I-type and can be described by Langmuiradsorption equation. Based on the principle of high adsorption capacity and highseparation factor, we choose ZC1326as the best material to be modified.NaOH, KOH, Na2CO3, K2CO3and NH3were used to impregnate ZC1326inorder to modify ACFs, the adsorption capacity for CH₄and N₂is been improved, andthere exists a best modifier concentration. It shouldn’t be too low to modify ACFs ortoo high to block pores, the ACF modified with5mol/L ammonia aqueous solution isbest.The ZC1326was modified by removing impurities using both acid and basetreatments. In this way, the ash content is reduced and the adsorption capacity for CH₄and N₂is increased with an accompanying improvement in the specific surface area.After we secondarily activated ZC1326with KOH as activator, adsorptioncapacity for CH₄and N₂is increased. Meanwhile, specific surface area is alsoimproved to certain degrees which is in favor of the adsorption and seperation ofACFs for CH₄and N₂.Adopting chemical activation method, the high specific surface area activatedcarbon was prepared from coal and charcoal bought from market by KOH as activator.The influence of the ratio of KOH to carbon, activation temperature and activationtime on adsorption properties were emphasized studied. If ratio of KOH to carbon,activation temperature and activation time exceed a certain threshold, it will causeexcessive ablation and lead to poorer adsorption performance of activated carbon, soactivation conditions of activated carbon in the actual production process should bereasonable and optimized. Under the experimental conditions, optimal conditions forpreparation of high specific surface area activated carbon are at the ratio of KOH tocarbon of4, activation temperature of700°C and hold time of30⁶0min.