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Framework dimensions

The popuiation baiance provides the mathematicai framework incorporating expressions for the various crystai formation, aggregation and disruption mechanisms to predict the finai particie size distribution. Note, however, that wiiiie particies are commoniy characterized by a iinear dimension the aggregation and particie disruption terms aiso require conservation of particie voiume. It was shown in Chapter 2 that the popuiation baiance accounts for the number of particies at each size in a continuous distribution. The quantity conserved is thus the number (popuiation) density and may be thought of as an extension of the more famiiiar mass baiance. The popuiation baiance is given by (Randoiph and Larson, i988)... [Pg.166]

This agreement in dimensions makes it highly probable that this is the framework of zunyite. [Pg.548]

Because of this, there is a real need for designing the general method, by means of which economical schemes can be created for equations with variable and even discontinuous coefhcients as well as for quasilinear non-stationary equations in complex domains of arbitrary shape and dimension. As a matter of experience, the universal tool in such obstacles is the method of summarized approximation, the framework of which will be explained a little later on the basis of the heat conduction equation in an arbitrary domain G of the dimension p with the boundary F... [Pg.591]

Figure 10.1 Framework types of some well-known zeolites with their specific pore size and pore network dimensions [5]. Figure 10.1 Framework types of some well-known zeolites with their specific pore size and pore network dimensions [5].
Because the pore dimensions in narrow pore zeolites such as ZSM-22 are of molecular order, hydrocarbon conversion on such zeolites is affected by the geometry of the pores and the hydrocarbons. Acid sites can be situated at different locations in the zeolite framework, each with their specific shape-selective effects. On ZSM-22 bridge, pore mouth and micropore acid sites occur (see Fig. 2). The shape-selective effects observed on ZSM-22 are mainly caused by conversion at the pore mouth sites. These effects are accounted for in the hydrocracking kinetics in the physisorption, protonation and transition state formation [12]. [Pg.55]

The framework for data collection, as depicted in Figure 2.1, lays down the focus and scope of this study. The regulation of human pharmaceuticals, as addressed in this study, has four dimensions administrative elements, regulatory functions, technical elements and level of regulation. As well as capturing the various dimensions of dmg regulation, this framework allows for comparison of dmg regulation between countries. [Pg.11]

One of the reactors that Degussa and the plant manufacturer Krupp-Uhde are currently inveshgating in the framework of a government-funded project has remarkably large outer dimensions and is being tested for pilot-scale feasibility (see Figure 1.23). [Pg.57]

F(r) was also computed from ab initio wave functions in the framework of the HF/SCF method using 3-21G and 6-31G basis sets due to the large size ofLR-B/081, the calculation has as yet been performed on isolated molecular fragments, adopting a geometry based on molecular dimensions from X-ray diffraction studies. [Pg.287]

The overall model is made up of two modules that are built within the same framework. One module focuses on the exploration of water reuse/recycle opportunities and the other on proper sequencing to capture the time dimension. To facilitate understanding, these modules are presented separately in the following sections. [Pg.74]

N anomaterials have been around for hundreds of years and are typically defined as particles of size ranging from 1 to 100 nm in at least one dimension. The inorganic nanomaterial catalysts discussed here are manganese oxides and titanium dioxide. Outside the scope of this chapter are polymers, pillared clays, coordination compounds, and inorganic-organic hybrid materials such as metal-organic frameworks. [Pg.226]

The induction of steric effects by the pore walls was first demonstrated with heterogeneous catalysts, prepared from metal carbonyl clusters such as Rh6(CO)16, Ru3(CO)12, or Ir4(CO)12, which were synthesized in situ after a cation exchange process under CO in the large pores of zeolites such as HY, NaY, or 13X.25,26 The zeolite-entrapped carbonyl clusters are stable towards oxidation-reduction cycles this is in sharp contrast to the behavior of the same clusters supported on non-porous inorganic oxides. At high temperatures these metal carbonyl clusters aggregate to small metal particles, whose size is restricted by the dimensions of the zeolitic framework. Moreover, for a number of reactions, the size of the pores controls the size of the products formed thus a higher selectivity to the lower hydrocarbons has been reported for the Fischer Tropsch reaction. [Pg.448]

These microporous crystalline materials possess a framework consisting of AIO4 and SiC>4 tetrahedra linked to each other by the oxygen atoms at the comer points of each tetrahedron. The tetrahedral connections lead to the formation of a three-dimensional structure having pores, channels, and cavities of uniform size and dimensions that are similar to those of small molecules. Depending on the arrangement of the tetrahedral connections, which is influenced by the method used for their preparation, several predictable structures may be obtained. The most commonly used zeolites for synthetic transformations include large-pore zeolites, such as zeolites X, Y, Beta, or mordenite, medium-pore zeolites, such as ZSM-5, and small-pore zeolites such as zeolite A (Table I). The latter, whose pore diameters are between 0.3... [Pg.31]


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See also in sourсe #XX -- [ Pg.81 ]




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Cluster framework dimensions

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