A novel pore structure tortuosity concept based on nitrogen sorption hysteresis data

Salmas, CE; Androutsopoulos, GP

dc.contributor.author	Salmas, CE	en
dc.contributor.author	Androutsopoulos, GP	en
dc.date.accessioned	2014-03-01T01:16:02Z
dc.date.available	2014-03-01T01:16:02Z
dc.date.issued	2001	en
dc.identifier.issn	0888-5885	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/13892
dc.subject	Nitrogen	en
dc.subject	Pore Structure	en
dc.subject.classification	Engineering, Chemical	en
dc.subject.other	Aluminum oxide membrane	en
dc.subject.other	Mercury entrapment	en
dc.subject.other	Mercury porosimetry	en
dc.subject.other	Nitrogen sorption hysteresis data	en
dc.subject.other	Pore configuration model	en
dc.subject.other	Pore structure	en
dc.subject.other	Porous glass	en
dc.subject.other	Tortuosity factors	en
dc.subject.other	Alumina	en
dc.subject.other	Catalysts	en
dc.subject.other	Glass	en
dc.subject.other	Hysteresis	en
dc.subject.other	Lignite	en
dc.subject.other	Mathematical models	en
dc.subject.other	Mercury (metal)	en
dc.subject.other	Molecular structure	en
dc.subject.other	Nitrogen	en
dc.subject.other	Pore size	en
dc.subject.other	Porous materials	en
dc.subject.other	Sorption	en
dc.subject.other	Diffusion in solids	en
dc.subject.other	aluminum oxide	en
dc.subject.other	glass	en
dc.subject.other	lignite	en
dc.subject.other	mcm 41	en
dc.subject.other	mercury	en
dc.subject.other	nitrogen	en
dc.subject.other	adsorption	en
dc.subject.other	article	en
dc.subject.other	catalyst	en
dc.subject.other	chemical structure	en
dc.subject.other	curve fitting	en
dc.subject.other	data analysis	en
dc.subject.other	diffusion	en
dc.subject.other	hysteresis	en
dc.subject.other	molecular size	en
dc.subject.other	porosity	en
dc.subject.other	volumetry	en
dc.title	A novel pore structure tortuosity concept based on nitrogen sorption hysteresis data	en
heal.type	journalArticle	en
heal.identifier.primary	10.1021/ie000626y	en
heal.identifier.secondary	http://dx.doi.org/10.1021/ie000626y	en
heal.language	English	en
heal.publicationDate	2001	en
heal.abstract	A corrugated pore structure model (CPSM-nitrogen)9 was employed to define a novel pore structure tortuosity concept. An empirical correlation is proposed for the prediction of tortuosity factors τCPSM as follows: τCPSM = 1+A[(Dmax,eff-Dmin,eff)/Dmean](Ns - 2)a. Constants A and a are adjustable parameters. The second factor reflects the influence of the intrinsic pore size distribution, and the third expresses the contribution of the nominal pore length parameter Ns. The latter is, by definition, the number of pore segments forming a single corrugated pore of the CPSM pore configuration model and represents the frequency of pore cross section variation per unit length along a characteristic catalyst pellet dimension. The determination of Ns and (Dmax,eff - Dmin,eff)/Dmean is accomplished by fitting the CPSM model over the pertinent nitrogen sorption hysteresis data. Coefficients A and a were found to be A = 0.69 and a = 0.58 by applying the empirical correlation for two specified materials of known tortuosity. The tortuosity factors for an anodic aluminum oxide membrane, MCM-41 materials, dried lignite, a porous glass, and several HDS catalysts were predicted to be 2.60, 1.2-1.13, 1.33-2.79, 6.60, and 2.75-10.07, respectively. Such values approximate the literature data. Mercury porosimetry runs on the HDS catalysts showed a proportional increase in mercury entrapment with an increase in the corresponding τCPSM values. The tortuosity factor of lignite increases proportionally with the pore volume evolution. Further testing of the proposed correlation requires a rigorous analysis of diffusion phenomena, based on the CPSM pore structure configuration, combined with effective diffusivity measurements.A corrugated pore structure model (CPSM-nitrogen)9 was employed to define a novel pore structure tortuosity concept. An empirical correlation is proposed for the prediction of tortuosity factors τCPSM as follows: τCPSM = 1 + A[Dmax,eff - Dmin,eff)/Dmean](NS - 2)a. Constants A and a are adjustable parameters. The second factor reflects the influence of the intrinsic pore size distribution, and the third expresses the contribution of the nominal pore length parameter NS. The latter is, by definition, the number of pore segments forming a single corrugated pore of the CPSM pore configuration model and represents the frequency of pore cross section variation per unit length along a characteristic catalyst pellet dimension. The determination of NS and (Dmax,eff - Dmin,eff)/Dmean is accomplished by fitting the CPSM model over the pertinent nitrogen sorption hysteresis data. Coefficients A and a were found to be A = 0.69 and a = 0.58 by applying the empirical correlation for two specified materials of known tortuosity. The tortuosity factors for an anodic aluminum oxide membrane, MCM-41 materials, dried lignite, a porous glass, and several HDS catalysts were predicted to be 2.60, 1.12-1.13, 1.33-2.79, 6.60, and 2.75-10.07, respectively. Such values approximate the literature data. Mercury porosimetry runs on the HDS catalysts showed a proportional increase in mercury entrapment with an increase in the corresponding τCPSM values. The tortuosity factor of lignite increases proportionally with the pore volume evolution. Further testing of the proposed correlation requires a rigorous analysis of diffusion phenomena, based on the CPSM pore structure configuration, combined with effective diffusivity measurements.	en
heal.publisher	AMER CHEMICAL SOC	en
heal.journalName	Industrial and Engineering Chemistry Research	en
dc.identifier.doi	10.1021/ie000626y	en
dc.identifier.isi	ISI:000166528400028	en
dc.identifier.volume	40	en
dc.identifier.issue	2	en
dc.identifier.spage	721	en
dc.identifier.epage	730	en