Rigid sphere molecular model enables an assessment of the pore curvature effect upon realistic evaluations of surface areas of mesoporous and microporous materials

Salmas, CE; Androutsopoulos, GP

dc.contributor.author	Salmas, CE	en
dc.contributor.author	Androutsopoulos, GP	en
dc.date.accessioned	2014-03-01T11:44:41Z
dc.date.available	2014-03-01T11:44:41Z
dc.date.issued	2005	en
dc.identifier.issn	0743-7463	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/37086
dc.subject	Microporous Materials	en
dc.subject	Molecular Modeling	en
dc.subject	Surface Area	en
dc.subject.classification	Chemistry, Physical	en
dc.subject.other	Adsorption	en
dc.subject.other	Hysteresis	en
dc.subject.other	Mathematical models	en
dc.subject.other	Microporous materials	en
dc.subject.other	Pore size	en
dc.subject.other	Sorption	en
dc.subject.other	Molecular surface	en
dc.subject.other	Pore curvature	en
dc.subject.other	Rigid spheres model (RSM)	en
dc.subject.other	Mesoporous materials	en
dc.title	Rigid sphere molecular model enables an assessment of the pore curvature effect upon realistic evaluations of surface areas of mesoporous and microporous materials	en
heal.type	other	en
heal.identifier.primary	10.1021/la0508644	en
heal.identifier.secondary	http://dx.doi.org/10.1021/la0508644	en
heal.language	English	en
heal.publicationDate	2005	en
heal.abstract	A gas adsorption rigid spheres model (RSM) was incorporated into the CPSM model (corrugated pore structure model) to correlate the pore surface areas obtained from the BET and CPSM methods. The latter is a method simulating the gas sorption hysteresis loop and enables the evaluation of surface areas S-CPSM through the integration of the pertinent pore size distributions. Thus, S-CPSM values are inherently influenced by pore curvature. The new CPSM-RSM version estimates surface areas S-CPSMfs that are independent of pore curvature and can be compared with the pertinent S-BET values. The RSM exploits the fact that a curved pore surface accommodates fewer molecules, assumed to behave as rigid spheres, than an equal flat one. Thus, the RSM accounts for a higher molecular surface coverage A(c) (nm(2)/molec.) in pores with marked curvature than that (i.e., A(f)) on a flat surface. The ratio A(c)/A(f) for nitrogen adsorbed on single pore sizes varies in the range A(c)/A(f) = 1.44 - 1.03 for pore sizes D = 1.5 - 15 nm, respectively. Also for D = 1.5 - 5.0 nm the S-CPSMfs and SBET values are lower by similar to 10-45% than the S-CPSM estimates. From the application of the CPSM-RSM model on several porous materials exhibiting all known types of sorption hysteresis loops, it was confirmed that S-BET approximate to S-CPSM (5%) and (S-CPSM - S-BET)/S-BET = 3-68% for the materials examined. In conclusion, the BET method may produce quite conservative surface area estimates for materials exhibiting pore structures with appreciable pore curvature, whereas the CPSM-RSM model can reliably predict both S-CPSM and S-CPSMfs = S-BET values.	en
heal.publisher	AMER CHEMICAL SOC	en
heal.journalName	Langmuir	en
dc.identifier.doi	10.1021/la0508644	en
dc.identifier.isi	ISI:000233371200036	en
dc.identifier.volume	21	en
dc.identifier.issue	24	en
dc.identifier.spage	11146	en
dc.identifier.epage	11160	en