Relationships among pore size, connectivity, dimensionality of capillary condensation, and pore structure tortuosity of functionalized mesoporous silica
| dc.contributor.author | Armatas, G. S. | en |
| dc.contributor.author | Salmas, C. E. | en |
| dc.contributor.author | Louloudi, M. | en |
| dc.contributor.author | Androutsopoulos, G. P. | en |
| dc.contributor.author | Pomonis, P. J. | en |
| dc.date.accessioned | 2015-11-24T16:46:21Z | |
| dc.date.available | 2015-11-24T16:46:21Z | |
| dc.identifier.issn | 0743-7463 | - |
| dc.identifier.uri | https://olympias.lib.uoi.gr/jspui/handle/123456789/9062 | |
| dc.rights | Default Licence | - |
| dc.subject | nitrogen sorption measurements | en |
| dc.subject | porous solids | en |
| dc.subject | catalytic activity | en |
| dc.subject | fractal dimension | en |
| dc.subject | hysteresis | en |
| dc.subject | model | en |
| dc.subject | aluminophosphates | en |
| dc.subject | prediction | en |
| dc.subject | particles | en |
| dc.subject | supports | en |
| dc.title | Relationships among pore size, connectivity, dimensionality of capillary condensation, and pore structure tortuosity of functionalized mesoporous silica | en |
| heal.abstract | Seven mesoporous forms of silica were prepared by controlled and gradual functionalization of the original SiO2 surface with silano-(trimethoxy)-propyl-imidazole groups. The degree of surface functionalization was n = 0.00, 0.23, 0.30, 0.40, 0.52, 0.60, and 0.85 and was controlled by previous knowledge of surface acidity, determined by temperature-programmed desorption of NH3. From N-2 adsorption/desorption measurements, the specific surface area S-p (m(2) g(-1)), the specific pore volume VP (cm(3) g(-1)), and the corresponding pore size distributions (PSDs) were determined. The connectivity c of the solids was also calculated according to the method of Seaton, and the dimensionality of capillary condensation D-cc was found using the thermodynamic method of Neimark. The increase of functionalization. resulted in a linear drop of S-p and V-p, and the maximum D-max of the PSD and the full width at half-maximum, fwhm similar to2sigma, of the distribution drop in a regular way whereas the ratio (D-max/2sigma) remains practically constant. The connectivity c also decreases from c = 12.5 at n = 0 to c = 3 at n = 0.60-0.85, presumably because of blocking of channels connecting various pores. The D-cc values decrease with increasing n values. Next, the co-called corrugated pore structure model, CPSM, was employed for the estimation of tortuosity tau of the porous solids and the simulation of the experimental adsorption/desorption isotherms. From those CPSM simulations, the corresponding specific surface area S-CPSM (m(2) g(-1)), the specific pore volume V-CPSM (cm(3), g(-1)), and the corresponding pore size distribution PSDCPSM were estimated. The tortuosity tau of the system drops with the degree of functionalization from tau = 4.22 at n = 0 to tau = 3.37 at the initial functionalization (n = 0.23) and subsequently remains practically constant at about tau = 3.40 +/- 0.10, for the same reasons which affect the connectivity, that is, blocking ofvarious pore channels. The comparison between the parameters V-p and V-CPSM is quite satisfactory. The S-CPSM values appear systematically higher by 8-23% compared to the S-p ones. The dimensionality of capillary condensation D-cc is related to the variance 2sigma of the PSD. The reasons and the limits of this relationship are discussed. | en |
| heal.access | campus | - |
| heal.fullTextAvailability | TRUE | - |
| heal.identifier.primary | Doi 10.1021/La020261h | - |
| heal.identifier.secondary | <Go to ISI>://000182389100009 | - |
| heal.identifier.secondary | http://pubs.acs.org/doi/pdfplus/10.1021/la020261h | - |
| heal.journalName | Langmuir | en |
| heal.journalType | peer reviewed | - |
| heal.language | en | - |
| heal.publicationDate | 2003 | - |
| heal.publisher | American Chemical Society | en |
| heal.recordProvider | Πανεπιστήμιο Ιωαννίνων. Σχολή Θετικών Επιστημών. Τμήμα Χημείας | el |
| heal.type | journalArticle | - |
| heal.type.el | Άρθρο Περιοδικού | el |
| heal.type.en | Journal article | en |
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