Application of spin-spin relaxation to measurement of surface area and pore size distributions in a hydrating cement paste

Scanning electron microscopic data, X-ray diffraction patterns and porosity measurements are consistent with a structure for an Mo-A12O3 catalyst series containing a single surface layer of Mo up to the point where the Mo loadings exceed the amount required for a monolayer. For greater Mo loadings than required for a monolayer, three dimensional orthorhombic MoO3 is also present. The cumulative pore volume, on an alumina basis, does not appear to be significantly altered by MoO3 loadings up to about 15 wt.%. The BET surface area, on an alumina basis, remains constant with Mo loading. However, the apparent surface area calculated from mercury penetration data decreases with Mo loading. For these materials with cylindrical pores, the Broekhoff-deBoer model for the calculation of pore size distributions produced closer agreement to the mercury penetration pore size distribution. This is in contrast to materials composed of nonporous spheres where the Broekhoff-deBoer model provided poorer agreement to mercury penetration results than either the Cohan or a packed sphere model. The results show that, within a factor of two the pore size distributions calculated from nitrogen adsorption and mercury penetration data are comparable.

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Ni and Cu Incorporated Mesoporous Nanocomposite Catalytic Materials

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2008.c154 ◽

2008 ◽

Vol 8 (2) ◽

pp. 549-556 ◽

Cited By ~ 7

Author(s):

Asli Nalbant ◽

Timur Dogu ◽

Suna Balci

Keyword(s):

Pore Size ◽

Surface Area ◽

Atomic Ratio ◽

Nanocomposite Materials ◽

Size Distributions ◽

Hydrothermal Route ◽

Average Pore ◽

Pore Size Distributions ◽

Xrd Patterns ◽

Mcm 41

Nickel and copper incorporated MCM-41-like mesoporous nanocomposite materials prepared by the direct hydrothermal synthesis and the impregnation procedures showed highly attractive pore structure and surface area results for catalytic applications. The XRD patterns showed that characteristic MCM-41 structure was preserved for the materials synthesized following an impregnation procedure before the calcination step. The surface area of the Cu impregnated material with a quite high Cu/Si atomic ratio (0.19) was 631 m2/g. Very narrow pore size distributions with an average pore diameter of about 2.7 nm were obtained as a result of plugging of some of the smaller pores by Cu nanoballs. For lower metal to Si ratios (for instance for Ni/Si = 0.06) much higher surface area values (1130 m2/g) were obtained. In the case of nanocomposite materials synthesized by the direct hydrothermal route, MCM-41 structure was not destroyed for samples containing metal to Si atomic ratios as high as 0.12. In the case of materials containing Cu/Si and Ni/Si ratios over 0.2 wider pore size distributions and some decrease of surface area were observed.

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The Preparation of High-Surface-Area Pt/SiO2 Catalysts with Well-Defined Pore-Size Distributions

Journal of Catalysis ◽

10.1006/jcat.1995.1083 ◽

1995 ◽

Vol 152 (2) ◽

pp. 291-305 ◽

Cited By ~ 35

Author(s):

W.Q. Zou ◽

R.D. Gonzalez

Keyword(s):

Pore Size ◽

Surface Area ◽

High Surface ◽

High Surface Area ◽

Size Distributions ◽

Pore Size Distributions

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Pore Size Distributions in Hardened Cement Paste by Sem Image Analysis

MRS Proceedings ◽

10.1557/proc-370-217 ◽

1994 ◽

Vol 370 ◽

Cited By ~ 34

Author(s):

Sidney Diamond ◽

Mark E. Leeman

Keyword(s):

Image Analysis ◽

Pore Size ◽

Cement Paste ◽

Hardened Cement ◽

Size Distributions ◽

Hardened Cement Paste ◽

Mercury Intrusion ◽

Sem Image ◽

Pore Size Distributions ◽

Sem Image Analysis

AbstractTechnical requirements for determining the size distribution of capillary pores in hardened cement paste by SEM image analysis are discussed. Results of such measurements are reported for a set of hardened cement pastes of w:c ratio 0.40 and 0.25, and of ages ranging from 1 to 28 days. Pore size distributions based on conventional mercury intrusion porisimetry are presented for the same pastes. Estimates of pore diameters by mercury intrusion are two orders of magnitude smaller than the sizes revealed by the image analysis. Diameters of air voids are even more drastically underestimated by mercury intrusion. Typical micrographs are provided to illustrate the physical reality of the image analysis results, and the technical reasons underlying the conventional misinterpretation of MIP results for hydrated cements are reviewed.

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The Effect of Pyrolysis Temperature and Formulation on Pore Size Distribution and Surfacearea of Carbon Aerogels

MRS Proceedings ◽

10.1557/proc-270-53 ◽

1992 ◽

Vol 270 ◽

Author(s):

S.S. Hulsey ◽

C.T. Alviso ◽

F.M. Kong ◽

R.W. Pekala

Keyword(s):

Pore Size ◽

Surface Area ◽

Pyrolysis Temperature ◽

Bet Surface Area ◽

Vitreous Carbon ◽

Basic Medium ◽

Carbon Aerogels ◽

Size Distributions ◽

Structure Property ◽

Pore Size Distributions

ABSTRACTRecently we reported the chemistry-structure-property relationships of organic aerogels, which are synthesized by the polycondensation of resorcinol and formaldehyde in a slightly basic medium, followed by supercritical drying. These materials can be pyrolyzed in an inert atmosphere to form vitreous carbon aerogels. As measured by gas adsorption techniques, the BET surface area and pore size distributions of micro and meso pores of the carbon aerogels are affected both by the pyrolysis temperature and the formulation. Definite trends are observed in our preliminary measurements; for example, the surface area decreases with increasing pyrolysis temperature until a plateau is reached at about 900°C. This paper explores the effects of pyrolysis temperature and aerogel density on the BET surface area and pore size distributions.

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