Mercury penetration method

One problem is that if the silica gel is not very strong, the structure collapses by the external pressure of mercury before pores are penetrated. It is for this reason that the nitrogen adsorption isotherm method is preferred for research purposes. Nevertheless, for strong bodies like industrial catalyst gels, the mercury penetration method is far more rapid not only in execution, but also in converting results to pore size distribution curves. 

The specific surface area was determined by a Micromeritics Model 2200 high-speed, surface-area analyzer using nitrogen as the adsorbate. The pore volume was determined by the mercury penetration method on a Micromeritics Model 900/910 series porosimeter. 

We have already mentioned in Sect. 6.2, 6.3 that the physicochemical conditions of the foaming process and the foam stability criteria determine the upper and lower limits of cell sizes so that, depending on the polymer type, composition, and foaming process conditions, the upper limit of size may be as large as a few millimeters 36,83-85) recently, it was believed that the minimum size of a plastic foam cell cannot be less than several dozens of microns (Table 2). However, by the application of scanning electron microscopy and the mercury penetration method, plastic foam structures were found to incorporate gas voids whose minimum dimensions were fractions of a micron, i.e. 2 or 3 orders of magnitude smaller than could be observed earlier in cellular polymers... 

There are two established methods for measuring the distribution of pore volumes. The mercury-penetration method depends on the fact that mercury has a significant surface tension and does not wet most catalytic surfaces. This means that the pressure required to force mercury into the pores depends on the pore radius. The pressure varies inversely with a 100 psi (approximately) is required to fill pores for which a = 10,000 A, and 10,000 psi is needed for a — 100 A. Simple techniques and equipment are satisfactory for evaluating the porervolume distribution down to 100 to 200 A, but special high-pressure apparatus is necessary to go below a = 100 A, where much of the surface resides. In the second method, the nitrogen-adsorption experiment (described in Sec. 8-5 for surface area measurement) is continued until the nitrogen pressure approaches the... 

Mercury-penetration Method By equating the force due to surface tension (which tends to keep mercury out of a pore) to the applied force, Ritter and Drake obtained... 

Wheeler has summarized the assumptions and accuracy of the mercury-penetration method. It is important to note that erroneous results would be obtained if the porous particle contains large void spaces that are... 

For a chosen value of plpo, Eqs. (8-22) and (8-23) give the pore radius above which all pores will be empty of capillary condensate. Hence, if the amount of desorption is measured for various plpo, the pore volume corresponding to various radii can be evaluated. Differentiation of the curve for cuniulative pore volume ys radius gives the distribution of volume as described in Example 8-6. Descriptions of the method of computation are given by several investigators. As in the mercury-penetration method, errors will result unless each pore is connected to at least one larger pore. 

Mercury penetration method was used to measure pore volume of the catalyst samples ( Micromeritics Pore Sizer 9320 ). 

There is considerable evidence that the product (r./.)(l — ) appearing in equations (4c) and (4b) approximately equals 1.0 since average pore radii determined, say, by the mercury penetration method (5), agree quite well with the ratio 2Vp/Sp. This agreement is no doubt due to the fact that a roughness factor of 2.0 is reasonable for many surfaces and the valqe of 6, the porosity, is about 0.5 for most catalysts. 

Mercury Penetration Method. Mercury docs not wet the surface of silica and, higher pressure is required to force the liquid into a small pore. Washburn (187) developed the equation... 

Merch Bricks. Term sometimes used in USA for building bricks that come from the kiln discoloured, warped or off-sized. Mercury Penetration Method. A procedure for the determination of the range of pore sizes in a ceramic material. It depends on the fact that the volume of mercury that will enter a porous body at a pressure of P dynes /cm2 is a measure of the volume of pores larger than a radius r cm where r = -2a cos8/P, a being the surface tension of mercury in dynes/cm and 6 being the contact angle between mercury and the ceramic. A development of the method has been described by R. D. Hill (Trans. Brit. Ceram. Soc., 59, 198,1960). 

Purcell Method. Name sometimes given to the MERCURY PENETRATION METHOD (q.v.) for determining pore-size distribution (W. R. Purcell, J. Petroleum Tech., 1, (2), 39,1949). 

Schenck Porosimeter. Apparatus for the determination of pore size DISTRIBUTION (q.V.) by the mercury PENETRATION METHOD (q.V.) it haS... 

The most common methods to determine pore size distributions are the A. mercury penetration method, B. nitrogen adsorption method, and C. molecular probe method. 

The mercury penetration method is based on the fact that mercury has a significant surface tension and does not wet most catalytic surfaces. For a cylindrical pore, the force acting against the entrance of mercury to the pores equals —Z trrcr cos 6. The external pressure applied to overcome this force is Trr P. At equilibrium, the two forces are equal and ... 

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