Study On Preparation,Modification Of Coal-Based Porous Carbon And Adsorptive Separation On CO₂/CH₄

As a green cleaning and low-carbon energy,coalbed methane(CBM)has became an important energy source in China and even all over the world.CBM predominantly consists of methane(CH₄),and also contains considerable quantity of carbon dioxide(CO₂),which could dramatically reduce the heating value of CBM and cause pipeline corrosion during transportation.Thus,the separation of CO₂ from CH₄ is inevitably demanded for low-quality CBM upgrading.In this paper,on the foundation of activation treatment of raw coal,N doping,S doping and N-S co-doping are used for modification.The as-prepared coal-based modificated porous carbon is used as adsorbent for CO₂capture and CO₂/CH₄ seperation,details as following:(1)Coal-based porous carbon with high specific surface area,desirable porosity structure and high N content was prepared through KOH activation and urea modification.According to Henry's law,the selectivity of NAPC-4 for CO₂/CH₄ can reach 5.77.Meanwhile,according to the ideal adsorption solution theory(IAST),the selectivity of NAPC-4 for binary mixtute CO₂/CH₄(15/85)is as high as 8.17,25°C and 1 bar,which displayed mediocre CO₂ adsorption performance.(2)In order to meet the requirement of new heteroatomic modification,env ironmental-benign sodium thiosulfate(Na₂S₂O₃)was used as S source.And then a series of s-doped coal-based porous carbon with high specific surface area wer e prepared by KOH activation.According to Henry's law,the selectivity of SAP C-2 for CO₂/CH₄ can reach 2.68.Meanwhile,by the IAST method,the selectivit y of SAPC-4 for binary mixtute CO₂/CH₄(15/85)can reach 4.46,at 25°C and 1bar.(3)The as-prepared S-doped porous carbon was choosed as raw material,and low corrosivity agent sodium amide(Na NH₂)was used as activator and N agent,the N-S co-doped coal-based porous carbon was fabricated though one-pot method.According to Henry's law,the selectivity of SNAPC-2 for CO₂/CH₄ can reach 4.83.Meanwhile,by the IAST method,the selectivity of SNAPC-2 for binary mixtute CO₂/CH₄(15/85)can reach6.73,at 25°C and 1 bar,which displayed high CO₂capture and desirable CO₂/CH₄separation selectivity.