Wide pore

Fig. 5.7 Adsorption isotherms of n-p>entane vapour on A), quartz and pyrex glass and (B), wide-pored silica gel. O,, quartz pyrex glass A, A wide-pored silica gel. Solid symbols denote desorption. (Courtesy...

Thus, in this case the simple form of equation (34) is quite adequate. Alternatively, employing a wide pore silica base in LC for separating small molecular weight... 

Poly (p-nitrophenyl acrylate)-coated wide-pore glass (WPG) was also used as an activated carrier for the immobilization of biospecific ligands and enzymes, A detailed description of properties of these sorbents and catalysts as well as some specific features of their functioning is given in Sect. 6. 

One notes in Table 1.2 a uniform increase in the adsorption energies of the alkanes when the microspore size decreases (compare 12-ring-channel zeohte MOR with 10-ring-channel TON). However, at the temperature of hydroisomerization the equilibrium constant for adsorption is less in the narrow-pore zeohte than in the wide-pore system. This difference is due to the more limited mobility of the hydrocarbon in the narrow-pore material. This can be used to compute Eq. (1.22b) with the result that the overall hydroisomerization rate in the narrow-pore material is lower than that in the wide-pore material. This entropy-difference-dominated effect is reflected in a substantially decreased hydrocarbon concentration in the narrow-pore material. 

The Phillips Cr/silica catalyst is prepared by impregnating a chromium compound (commonly chromic acid) onto a support material, most commonly a wide-pore silica, and then calcining in oxygen at 923 K. In the industrial process, the formation of the propagation centers takes place by reductive interaction of Cr(VI) with the monomer (ethylene) at about 423 K [4]. This feature makes the Phillips catalyst unique among all the olefin polymerization catalysts, but also the most controversial one [17]. 

Fig. 3.23 shows pore volume distributions of some commercially important porous materials. Note that zeolites and activated carbon consist predominantly of micropores, whereas alumina and silica have pores mainly in the me.sopore range. Zeolites and active carbons have a sharp peak in pore size distribution, but in the case of the activated carbon also larger pores are present. The wide-pore silica is prepared specially to facilitate internal mass-transfer. 

Figure 3.23. Pore volume distributions (Nt physi.sorption) of a. wide-pore silica, b. y-alumina, c. a-alumina, d. activated carbon, e. Raney Nickel and f. ZSM-5.

Application of HPLC-MS to the analysis of a black tea liquor was studied in a paper by Bailey 39 a great deal of useful information could be obtained without sample pretreatment. A tea liquor was applied to a wide-pore HPLC column connected to a mass spectrometer by a VG Plasmaspray interface. Pseudo-molecular ions were obtained from the flavanols, flavanol gallates, chlorogenic acids, 4-coumarylquinic acids, and caffeine, but the flavanol glycosides were extensively fragmented by the interface. Fragments were obtained from unresolved polymer that supported its previous designation as a flavanol polymer. 

Figure 237 shows the pore size distribution of narrow pore (A) and wide pore Silicagel (B). 

In the main part, dealing with complex compounds of cadmium and mercury, those with complicated organic ligands are not considered, neither are complexes with bio-relevance systematically described. However, it is unavoidable to address the formation of frameworks with the metals and certain organic ligands, and even seemingly simple compounds like Cd(CN)2, especially in the presence of appropriate guest molecules, tend to form wide-pore host frameworks. 

Tanaka, N., Kimata, K., Mikawa, Y., Hosoya, K., Araki, T., Ohtsu, Y., Shiojima, Y., Tsuboi, R., Tsuchiya, H. (1990). Performance of wide-pore silica- and polymer-based packing materials in polypeptide separation the effect of pore size and alkyl chain length. J. Chromatogr. 535, 13-31. 

The wide-pore H-Beta zeolite has strong Bronstcd acid hydroxyl groups and other advantage chemical environment which govern the adsorption and consecutive conversion of methanol to dimethyl ether and further to hydrocarbons, mostly isobutane. This character can be modified by Fe ion-exchange. 

Matrixes Three types of paper filters (i). Filtrak, Germany, the filter Number 388 [(0.025) - soft, wide pores] filters No. 90 (0.15) and No. 90 (0.25) - dense, narrow pores) (ii). chromatographic papers FN-5, FN-11 (Germany) the kapron membrane (pore size 0.2 microns) and (iii). the membrane Vladipor MFA-MA No. 6 (Kazan industrial associations Tasma )] were applied to matrixes for biotests. The circles (6 -10 mm dia) are cut out from the matrixes materials by special instrument. The most stable results are received with use of matrixes of chromatographic papers FN-5, FN-11. 

Dalai, A.K., Das, T.K., Chaudhari, K.V., Jacobs, G., and Davis, B. H. 2005. Fischer-Tropsch synthesis Water effects on Co supported on narrow and wide-pore silica. Appl. Catal. 289 135-42. 

Fischer-Tropsch Synthesis Comparison of the Effect of Co-Fed Water on the Catalytic Performance of Co Catalysts Supported on Wide-Pore and Narrow-Pore Alumina... 

Degussa C y-A1203 Wetted, dried, calcined Wide pore 117 0.80 22.9... 

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