Preparation And Modification Of Biomass Activated Carbon Based On Separation And Enrichment Of Low Concentration Coalbed Methane

Guizhou Guizhou Province,which is known as “Jiangnan Coal Sea”,rich in coalbed methane resources,accounting for 22% of the total national resources.Because of unique topography in Guizhou,the coalbed methane been extracted is in low concentration?CH₄<30%?.most of them are emptied directly and cannot be used,which not only causes a serious waste of resources,but also exacerbates environmental pollution.So the reasonable development and utilization of low concentration coalbed methane have significant influence on developing the economical benefits and environmental protection benefits.Vacuum pressure swing adsorption?VPSA?technology is widely used in low concentration coalbed methane separation.Efficient and stable adsorbents is the key technology.In this paper,four kinds of biomass wastes were selected as raw materials to prepare activated carbon and the product was modified.Based on the characteristics of low concentration coalbed methane,the simulative gas?CH₄20%,N264% and O216%?were prepared,single column VPSA technology?adsorb in atmosphere and desorb vacuum condition?were used in the research,the specific content is as follows:A series of activated carbons?pAC,mAC,hAC and z AC?were prepared by H3PO4 activation method with grape pip,wood sawdust,walnut shell and bamboo,sawdust respectively,the effect of different activated carbon on the separation and enrichment of low concentration coalbed methane were study,and compare with commercial activated carbon?sAC?.The relationship between adsorption capacity of activated carbon and its pore structure/surface chemical properties were researched by N2 adsorption / desorption isotherm,FTIR and Bohem titration.Results showed that the adsorption capacities of methane on these activated carbons is in the following order: pAC >> mAC> hAC > sAC > zAC.The pAC has the largest methane adsorption capacity?22.64 m L/g?due to its largest amount of surface basic group,and the surface basic group content is larger than its surface acid group content.Different effect of Ni?II?doping and Ni?II?modified on the CH₄ adsorption capacity of activated carbon was compared.The effects of Ni?II?doping amount,activation temperature and Ni?II?modification on the adsorption and enrichment performance of activated carbon were investigated.Results showed that the adsorption capacity of activated carbon can be improved by Ni?II?doping,activation temperature and Ni?II?modification.Among them,the adsorption capacity of 4% Ni-p AC / 4% NihAC?prepared by 4% Ni?II?doping grape seed / walnut shell raw materials?was 30.61ml/g and 24.81ml/g,Which is 35.2% and 138.56% higher than that of pAC and hAC.The adsorption capacity of 4% Ni-pAC-700 is 37.15 mmol/g,which is 64.09% higher than that of pAC.The adsorption capacity of pAC-4% Ni-700 prepared by 4% Ni?II?modified pAC was 37.47 ml / g.The adsorption properties of activated carbons were characterized by N2 adsorption/desorption isotherm,FTIR and Bohem titration,the relationship between adsorption properties and pore structure/surface chemical properties was obtained.The effect of pAC chitosan carbonized aerogels modification on the separation and enrichment performance of CH₄ was studied.The effects of drying methods and activation temperature were investigated,Results showed that the adsorption capacity of pAC-DW-900 was the best,and unit adsorption capacity was about 39.37 ml / g,which is73.90% higher than that of pAC.The CH₄ concentration in coalbed methane can be increased from 20% to 40.18%.The activated carbons were characterized by N2 adsorption/desorption isotherm,FTIR and Bohem titration,and the relationship betweenadsorption properties of the activated carbon and its pore structure/surface chemical properties was obtained.