Mercury porosimetry measurements

In addition, mercury intrusion porosimetry results are shown together with the pore size distribution in Figure 3.7.3(B). The overlay of the two sets of data provides a direct comparison of the two aspects of the pore geometry that are vital to fluid flow in porous media. In short, conventional mercury porosimetry measures the distribution of pore throat sizes. On the other hand, DDIF measures both the pore body and pore throat. The overlay of the two data sets immediately identify which part of the pore space is the pore body and which is the throat, thus obtaining a model of the pore space. In the case of Berea sandstone, it is clear from Figure 3.7.3(B) that the pore space consists of a large cavity of about 85 pm and they are connected via 15-pm channels or throats. 

Mercury porosimetry measurements for a partially sintered alumina preform showed a bimodal pore size distribution with neck diameter Dn = 0.15 pm [Manurung, 2001], As a comparison with the pore sizes and distribution of the preform measured by porosimetry, SEM micrographs (Fig. 5.1) were taken before and after infiltration. Based on SEM examination, the pores in the preform before infiltration ranged in size from r 0.1-0.5 pm. Assuming an average pore radius of 0.3 pm, this radius is approximately four times larger than the pore-neck radius (Dn = 0.15 pm, so pore radius = 0.075 pm) determined by mercury porosimetry. 

The amorphous aluminosilicate gel (AAA-alumina) used in this study contains about 80.4% Si02, 19.4% A1203 and 0.056ft Na20. Mercury porosimetry measurements have indicated a 479 nr/9 surface area and 1.67 cc/g pore volume the average pore diameter of the dried gel was 134 A. 

Rieckmann and Keil (1997) introduced a model of a 3D network of interconnected cylindrical pores with predefined distribution of pore radii and connectivity and with a volume fraction of pores equal to the porosity. The pore size distribution can be estimated from experimental characteristics obtained, e.g., from nitrogen sorption or mercury porosimetry measurements. Local heterogeneities, e.g., spatial variation in the mean pore size, or the non-uniform distribution of catalytic active centers may be taken into account in pore-network models. In each individual pore of a cylindrical or general shape, the spatially ID reaction-transport model is formulated, and the continuity equations are formulated at the nodes (i.e., connections of cylindrical capillaries) of the pore space. The transport in each individual pore is governed by the Max-well-Stefan multicomponent diffusion and convection model. Any common type of reaction kinetics taking place at the pore wall can be implemented. 

This work has been supported by Sandia National Laboratories ( 55-6778) and the ALCOA Foundation. Nitrogen adsorption and mercury porosimetry measurements were performed by S.B. Ross. Aerogels were prepared by Carol S. Ashley of SNL. 

Transmission electron microscopy (TEM) observations, nitrogen adsorption-desorption and mercury porosimetry measurements indicated that increasing EDAS/TEOS ratio results in (a) a decrease of the building block particle size, (b) an increase of the specific surface area (S ), (c) an increase of mesopore volume determined at saturation pressure of N (Vp) and a decrease of the total pore volume (V,) (d) a general shift of the pore size distribution towards smaller pores, (e) an increase of the pressure of transition (P,), above which mercury can intrude the sample without destroying the pore structure [1-3]. To explain this behaviour... 

Nitrogen sorption measurements were performed by use of a Sorptomatic 1900 Turbo apparatus by Carlo Erba Instruments. All samples were degassed at 393 K before measurement for at least 24 hours at 10 mbar. The mercury porosimetry measurements were carried out on a Porosimeter 2000 apparatus by Carlo Erba Instruments. A contact angle of 141.3° for Hg was used. The samples were degassed at 393 K before measurement for 24 h. SEM of the porous glass membranes was carried out on a Phillips ESEM XL 30 PEG microscope. 

Freitag F, Kleinebudde P. How do roll compaction / dry granulation affect the tableting behaviour of inorganic materials Microhardness of ribbons and mercury porosimetry measurements of tablets. Eur Pharm Set 2004 22 325-333. 

SEM measurements were performed using a field emission electron microscope (Hitachi S4200). Samples were coated ( 2nm) with sputtered platinum. Mercury porosimetry measurements (Micromeritics, ASAP, Autopore II 9220) were made on outgassed samples of small fragments ( 100 mg) with intrusion pressures correspondmg to pore diameters (pm) in the range 10 to 5x10" ... 

The aim of this work is to explore the applicability of the sol-gel method for the preparation of Ag/Si02 and Cu/Si02 catalysts and to see whether such a method can yield silver and copper species stabilized by the carrier. Characterization of the catalyst structure by several physical and chemical techniques, including N2 adsorption-desorption isotherms, mercury porosimetry measurements, X-ray diffraction and transmission electron microscopy, has been used to correlate the microstructure of Ag/Si02 and Cu/Si02 catalysts with their catalytic performance. 

N2 adsorption-desorption isotherms were determined at 77 K after outgassing for 24 h at room temperature. The mercury porosimetry measurements were performed between 0.01 and 200 MPa after outgassing the sample monolith for 2 h at ambient temperature. The size of silica and metallic particles was examined by transmission electron microax)py (TEM). The composition and size of the metallic particles were examined by X-ray diffraction (XRD). 

Figure 2, Schematic of the dilatometer used for the initial mercury porosimetry measurements.

Fig. 5.28 Typical results of the mercury porosimetry measurements for the dried samples (continuous lines) and afier removal of water by propane (dashed lines), (according to [59]), / , the threshold radius...

Pore size distribution and connectivity, which may be obtained from experimental nitrogen adsorption or mercury porosimetry measurements [46-48]. 

Specific surface n. Of porous solids, massed fibers, and particulate materials, the total surface area per unit of bulk volume or per unit mass. Specific surface is usually measured by gas adsorption or estimated from mercury-porosimetry measurements. 

It is obvious that the volume fraction which can be covered by spheres with radius rs increases with decreasing radius rs. This can physically be related, for example, to mercury porosimetry measurements. Using high pressures, mercury occupies more or less the complete pore phase, which corresponds to small radii rs in the definition of continuous pore size distribution. On the other side, low pressures correspond to large radii rs- The reason is that for low pressures, the hydrophobicity dominates the pressure to fill the pore phase. Hence for low pressures, only larger pores are filled. More detailed information on this topic is available elsewhere ([9, 66, 67, 69, 71] and references therein). 

Nitrogen adsorption measurements at liquid nitrogen temperature (77 K) were performed with a commercial apparatus (ASAP 2400, Micromeritics) ter sample outgassing at 473 K for 2h, in vacuum. The BJH method in the desorption branch of the isotherms was applied to calculate the pore size distribution. Pore shape was inferred from the shape of hystheresis loop (18). Mercury porosimetry measurements were performed with an Autopore II apparatus (Micromeritics), after drying the sample overnight at 423 K. 

H. Giesche Interpretation of hysteresis fine-structure in mercury-porosimetry measurements, in Materials Research Society Symposium Proceedings, Volume 371, Advances in Porous Materials (Komarneni S., Smith D.M. Beck J.S., eds) Materials Research Sodety, Pittsburgh, PA (1995) 505-510... 

Mercury Porosimetry and Capillary Flow Porometry - Pore Size Determination In a mercury porosimetry measurement, pressure is used to force mercury into filling the pores and voids of the material. The method is based on the capillary rise phenomenon which exists when a non-wetting liquid climbs up a narrow capillary. As the pressure is increased, mercury infiltrates the pores to occupy a subset of the total pore space, the extent of which depends on the applied external pressure. The injected volume of mercury as a function of pressure is recorded. The pore size and distribution can be resolved using the Young and Laplace model [43]. The pore sizes that can be determined by mercury porosimetry range from a few nanometers to a few hundreds of microns. The method is invasive in that not all the mercury will be expelled from the pores and pores may collapse as a result of the high pressures. Due to this and environmental concerns about mercury pollution mercury porosimetry method is becoming less popular. 

---