Pore size distributions comparison

Pore size distribution—comparison of results by mercury porosimetry and by adsorption of nitrogen... 

This abbreviated equation can be used for pore size distribution comparisons of similar samples when absolute pore size is not necessary. If, however, comparison of absolute pore sizes is required, the contact angles should be measured for all samples [42]. 

Fig. 3.3.3 (a) Hahn echo ]H intensity during heating cycle of cyclohexane filling the pores of catalyst pellets, (b) Pore size distribution obtained from (a) in comparison with BET 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. 

B) Pore size distribution (solid line) obtained from DDIF, in comparison with mercury (Hg) porosimetry (dashed line). The peak in the... 

FIGURE 8.2 Comparison of pore size distributions for the (solid) air calcined and... 

The pore size distribution in highly activated carbon HSGD measured with low temperature nitrogen adsorption shows absence of the curve maximum in the range of 75-900 A (Fig. 29.6). In comparison with the pore distribution of SCN hemosorbent, HSGD has predominantly meso- and small macroporous structure, with some... 

COMPARISON WITH EXPERIMENTS AND CALCULATION OF PORE SIZE DISTRIBUTIONS... 

Figure 2. Comparison of pore size distribution of MCM-41 samples by regularization with the XRD pore diameter...

Figure 3. Comparison of pore size distribution of mixture of MCM-41 materials by regularization with the XRD pore diameter, as well as pore size distribution estimated from pure components (a) C12+C18, (b) C12+C16, (c) C10+C14...

Comparison of the pore size distribution determined by the present method with that from the classical methods such as the BJH, the Broekhoff-de Boer and the Saito-Foley methods is shown in Figure 4. Figure 5 shows a close resemblance of the results of our method with those from the recent NLDFT of Niemark et al. [16], and XRD pore diameter for their sample AMI. The results clearly indicate the utility of our method and accuracy comparable to the much more computationally demanding density functional theory. There are several other methods published recently (e. g. [21]), however space limitations do not permit comparison with these results here. It is hoped to discuss these in a future publication. 

Studies undertaken with petroleum feedstocks to elucidate an understanding of hydrodemetallation reactions have yielded ambiguous and in some cases conflicting results. Comparison of kinetic phenomena from one study to the next is often complicated. Formulation of a generalized kinetic and mechanistic theory of residuum demetallation requires consideration of competitive rate processes which may be unique to a particular feedstock. Catalyst activity is affected by catalyst size, shape, and pore size distribution and intrinsic activity of the catalytic metals. Feedstock reactivity reflects the composition of the crude source and the molecular size distribution of the metal-bearing species. 

Comparison of Pore Size Distributions Determined by Mercury Injection and Gas Breakthrough Experiments... 

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. 

Table 1 summarises the most important results from the investigation of metal doping. In this table the results of MAP treatment are combined with effects of firing temperature and doping. As can be seen in Table 1, y-alumina membranes with pore radii as low as 2.0 nm (Kelvin radius) may be obtained after firing at 600°C. Note that an instrumental standard error of 0.5 nm (90% reliability) is common in permporometry. This technique should therefore only be used for comparison purposes and to obtain a qualitative impression of the pore-size and pore-size distribution of the material under investigation. 

---