Ultramicroporous Carbon Granules With Narrow Pore Size Distribution For The Adsorption And Separation Of Mixture Gases

Under the background of rapid global economic development and increasingly strong demand for green and clean energy,methane has a high calorific value and wide distribution of resources,which is considered to be one of the most potential natural gas energy sources.Separation of CH₄/N₂ and methane enrichment from low concentration coalbed methane is of great significance for environmental protection,energy conservation and emission reduction.Pressure swing adsorption（PSA）is a methane enrichment technology suitable for coal seam gas extraction in China.At the same time,the development of suitable adsorbent materials with the best separation effect is the key to the application of adsorption separation technology.Porous carbon materials have attracted much attention because of their good stability,cheap and easy to obtain,simple preparation and easy industrialization.In this paper,biomass waste oil-tea shell was selected as carbon source to prepare camellia shell granular activated carbon by chemical activation method,and a new type of granular ultramicroporous carbon material with excellent coal-bed methane enrichment performance was developed.The narrow pore sizes of the obtained ultramicroporous carbon particles are 0.5～0.6 nm.To our knowledge,such a concentration of pore size and uniform distribution of carbon particles has never been obtained.Carbon particles can be directly used in the adsorption column without the need for granulation or pelletization process.The CH₄ absorption of porous carbon（GOC-2）from granular oil-tea shell reached the highest level of 1.82 mmol g^-1 at 1 bar and 298 K,and the CH₄/N₂ selectivity was 5.8.The dynamic breakthrough experiment and PSA simulation experiment further confirmed the excellent CH₄/N₂ separation performance.This work provides a new strategy for the development of ultramicroporous carbon particles and the design of highly efficient adsorbents for CH₄/N₂ separation.At the same time,the adsorption capacities of low carbon hydrocarbons for GOCs samples at 1bar and 298 K were as follows:C₂H₂(4.85 mmol g^-1),C₂H₄(4.72 mmol g^-1),C₂H₆(5.43 mmol g^-1),C₃H₄(7.87 mmol g^-1),C₃H₆(6.43mmol g^-1),and C₃H₈(5.99 mmol g^-1).It is worth noting that the reverse adsorption characteristics of GOCs on ethane/ethylene are conducive to the study of efficient separation of low carbon hydrocarbons.