Study On Glucose-derived Porous Carbon For CO₂/CH₄/N₂ Adsorptive Separation In Coalbed Methane

Coal-bed methane(CBM)is an unconventional natural gas,with a main composition of CH₄,as well as large amount of CO₂and N₂.CH₄in the CBM is a kind of high quality and clean gas fuel.Meanwhile,it is also one of detrimental gases influencing mining underground coal and an important harmful source leading to atmospheric greenhouse effect.The direct emission of low concentration CBM not only results in the waste of energy,but also causes serious safety and environmental problems.Pressure swing adsorption(PSA)technique is an effective method for CO₂/CH₄/N₂separation and CH₄enrichment for low concentration CBM.In this paper,porous laminated carbon sheets and N-doped porous carbon spheres were prepared using glucose as carbon source by different synthesis routes,which exhibited excellent performance for CO₂/CH₄/N₂adsorptive separation.The specific contents are as follows:(1)Porous laminated carbon sheets with high specific surface area were sythesized by sugar gum method,which using glucose solution as source and potassium oxalate as active agent.The as-prepared AJPs exhibits CO₂,CH₄and N₂adsorption capacities of4.07 mmol·g^-1,1.81 mmol·g^-1and 0.59 mmol·g^-1,respectively,at 25?and 1 bar.According to the ideal adsorption solution theory(IAST),the selectivities of binary mixture gases CH₄/N₂and CO₂/CH₄are predicted.The selectivities of AJPs for binary mixtute CH₄/N₂(30/70)and CO₂/CH₄(10/90)can reach to 4.6 and 4.13,respectively,at25?C and 1 bar.(2)Nitrogen(N)-doped porous carbon spheres were prepared from sustainable biomass glucose via hydrothermal carbonization,CO₂activation,and urea treatment.The specific surface area of ACSs-N is 697 m²·g^-1and the nitrogen content is 6.5 wt%.The as-prepared ACSs-N exhibits CO₂,CH₄and N₂adsorption capacities of 3.03mmol·g^-1,1.30 mmol·g^-1and 0.40 mmol·g^-1,respectively,at 25?and 1 bar.According to IAST method,the selectivities of binary mixture gases CH₄/N₂and CO₂/CH₄are predicted.The selectivities of ACSs-N for binary mixtute CO₂/CH₄(30/70)and CO₂/CH₄(10/90)are as high as 4.9 and 7.26,respectively,at 25?and 1 bar.