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1、NatureoftheporosityinAmericancoalsH.Gan,S.P.NandiandP.L.Walker,JrDepartmentofMaterialSciences,ThePennsylvaniaStateUniversity,UnivwsityPark,Pennsylvania16802,USAf&eivedOctober1971)Thenatureoftheporosityinanumberof40X70(i.e.-40+70)meshsizeAmericancoals,var
2、yinginrankfromanthracitetolign,ite,hasbeenstudiedusingthefollowingcharacterizationtechniques:gasadsorption,heliumandmercurydisplacement,andmercuryporosimetry.Surfaceareascalculatedfromcarbondioxideadsorptionat298Kareconsistentlyhigherthanthosecalculatedf
3、romnitrogenat77K,indicatingthemolecularsievecharacterofthecoals.Totalporevolumeshavebeenmeasuredinthediameterranga12-29600Aandthendividedintomacropores(300-29600A),transitionalpores(12-300A),andmicropores(4-128).Coalsvarywidelyintheirtotalporevolumes(por
4、ositiesrangebetween4.1and23.2%).Inthelower-rankcoals(carboncontentlessthan75%).porosityisprimarilyduetothepresenceofmacropores.Incoalshavingacarboncontentintherange76-84%.about80%ofthetotalopenporevolumeisduetomicroandtransitionalpores,whereasinthecoalso
5、fhighercarboncontentmicroporositypredominates.Coalshavingabout35-55%oftheirtotalopenporevolumeinthetransitionalrangeareexpectedtobemostsuitableforuseforadsorptionoforganicmoleculesfromsolution.Thus,theyareofinterestaspossiblematerialstobeusedinwaterpurif
6、ication.Ingeneral,theseresultsareconsideredtobeofimportanceinunderstandingtheextentandrateofinteractionofcoalswithgasesandliquids.Applicationofphysicalmethodstothestudyofcoalporestructureofcoalsascharacterizedbysuchparametersstructurehasindicatedthatcoal
7、possessesauniqueporeastotalporevolumefromheliumandmercurydensities,system.Hirsch,fromX-raydiffractionmeasurements,hasporesurfaceareasfromadsorptionofnitrogenat77Kanddemonstratedthat,broadly,threetypesofstructurearecarbondioxideat298K,macroporesizedistrib
8、utionfrompresentinawiderangeofcoals:(1)theopenstructuremercuryporosimetry,andsizedistributionofporesbelowcharacteristicoflow-rankcoalswithhighporosity;(2)the300Acalculatedfromnitrogenisothermsmeasuredat77K.liquidstructureo
