Sieve geometry

Further examination of the data in Table I reveals several interesting points. Sieve geometry affects selectivity somewhat as shown by the slight differences between powdered, 20-40 mesh size, and tableted Na-Y sieve. Both basic sodium and ammonium-Y sieves and acidic rare earth-Y sieves... 

Electron Spin Resonance Spectroscopy. Several ESR studies have been reported for adsorption systems [85-90]. ESR signals are strong enough to allow the detection of quite small amounts of unpaired electrons, and the shape of the signal can, in the case of adsorbed transition metal ions, give an indication of the geometry of the adsorption site. Ref. 91 provides a contemporary example of the use of ESR and of electron spin echo modulation (ESEM) to locate the environment of Cu(II) relative to in a microporous aluminophosphate molecular sieve. 

A surprisiagly large number of important iadustrial-scale separations can be accompHshed with the relatively small number of zeoHtes that are commercially available. The discovery, characterization, and commercial availabiHty of new zeoHtes and molecular sieves are likely to multiply the number of potential solutions to separation problems. A wider variety of pore diameters, pore geometries, and hydrophobicity ia new zeoHtes and molecular sieves as weU as more precise control of composition and crystallinity ia existing zeoHtes will help to broaden the appHcations for adsorptive separations and likely lead to improvements ia separations that are currently ia commercial practice. 

Alpha-quartz has many useful properties which lead to its wide use in industry as a glass, ceramic and molecular sieve. However, undoubtedly its most technically important use occurs by virtue of its piezo-electric properties, which allow it to be used as a frequency regulating device in satellites, computers, and the ubiquitous quartz-watch . Unfortunately, it has been found that quartz crystals are susceptible to damage by radiation, and that this is associated with the presence of defects in the crystal lattice. These defects, particularly aluminum and hydrogen, are grown into the crystal and so far have proved impossible to remove. This problem has been the cause of intensive research, which has led to some information on the possible types of defects involved, but has failed to produce details of their geometries, and the way in which they interact. 

A wide variety of extraction column forms are used in solvent extraction applications and many of these, such as rotary-disc contactors (RDC), Oldshue-Rushton columns, and sieve-plate column extractors, have rather distinct compartments and a geometry, which lends itself to an analysis of column performance in terms of a stagewise model. As the compositions of the phases do not come to equilibrium at any stage, however, the behaviour of the column is therefore basically differential in nature. 

Linderic acid, physical properties, 5 31t Linde sieve tray, 23 338 Lind, James, 25 746-747 Linear geometry, for metal coordination numbers, 7 574, 575t Linear 1-olefins, properties of, 17 711t Linear acceleration, exponents of... 

As described above, a number of empirical and analytical correlations for droplet sizes have been established for normal liquids. These correlations are applicable mainly to atomizer designs, and operation conditions under which they were derived, and hold for fairly narrow variations of geometry and process parameters. In contrast, correlations for droplet sizes of liquid metals/alloys available in published literature 318]f323ff328]- 3311 [485]-[487] are relatively limited, and most of these correlations fail to provide quantitative information on mechanisms of droplet formation. Many of the empirical correlations for metal droplet sizes have been derived from off-line measurements of solidified particles (powders), mainly sieve analysis. In addition, the validity of the published correlations needs to be examined for a wide range of process conditions in different applications. Reviews of mathematical models and correlations for... 

The solution of the gas flow and temperature fields in the nearnozzle region (as described in the previous subsection), along with process parameters, thermophysical properties, and atomizer geometry parameters, were used as inputs for this liquid metal breakup model to calculate the liquid film and sheet characteristics, primary and secondary breakup, as well as droplet dynamics and cooling. The trajectories and temperatures of droplets were calculated until the onset of secondary breakup, the onset of solidification, or the attainment of the computational domain boundary. This procedure was repeated for all droplet size classes. Finally, the droplets were numerically sieved and the droplet size distribution was determined. 

Fig. 12 CFD Images of the flow pattern as a function of the static mixer geometry for a periodic section of the reactor top double axe, bottom sieve plates...

Figure 9.7a shows values of stable drop diameters that are calculated with Eqs. (9.3) and (9.4) for special conditions for the liquid system toluene-water as a function of the product of pulse amplitude, a, and frequency, /, the so-called pulse intensity. Figure 9.7b is a parity plot and shows that Eq. 9.4 describes the measured drop sizes for a wide range of velocities and parameters of the sieve tray geometry quite well. 

Catalytic activity of metal ions coordinated to the framework of mesoporous molecular sieves atracted attention at first. Recently, catalytic activity of the metal ions incorporated into extraffamework positions of the MCM-41 in various reactions was also reported [3], But, the site geometry, coordination and distribution of the metal ions in the extraframework sites of the MCM-41 host matrix are not understood, and only a few papers have dealt with this problem. For dehydrated Mn-(A1)MCM-41, only one type of single cation was reported [4],... 

This tray efficiency term (C) deserves further examination. It is derived from an empirical equation presented in Ref. Al, p. 183. The correlation accounts for the individual geometry of the sieve plate and other essential operating variables. It takes the form ... 

Another technique for removing spillage from a diked area is the use of an all-purpose sorbent. The effectiveness of using sorption as a removal technique is influenced by factors such as the physical and chemical attraction between the spilled material and the sorbent, the surface geometry and area of the sorbent, the contact time between the materials, and the density ratio of the spilled fluid and the sorbent (Bauer et al., 1975). Some effective sorbents include polymethacrylate foam resins, propylene fibers, molecular sieves, expanded clays, polyolefins, polymethylmethacrylates, and polystyrene sulfonates (Bauer et al., 1975). 

The question of which lattice components to include in the interpretive analysis reduces to the experimental problem of comparing systems of similar geometry but which contain different species in the lattice—e.g., Ge or Th in substitution for Si (1) S or F in substitution for O or OH, and say 2Na+ for lCa+2. The effect of change of cation is well known. In limiting cases it modifies the Molecular Sieve effect in zeolites. For host substituents, the availability of suitable systems is limited. The present work offers a comparison between a normal aluminosilicate and the same species after subjection to a substitution of halogen for oxygen and hydroxyl. 

In seeking an explanation for these findings, we must take into account the geometry of the pores in addition to their size. As we have seen, the intracrystalline pores of the Silicalite/ZSM-5 system are for the most part tubular and of 0.55 nm diameter. In such a confined space, a three-dimensional array of the hydrogen-bonded water structure cannot be accommodated without some considerable distortion of the directional hydrogen bonds. The situation is quite different in the case of carbon molecular sieves, which have slit-shaped pores. 

---