Unit cell formula

Table I. Unit cell formulae and sources of the Na+-saturated layer silicate clays.

Ideal unit cell formula 2S.6L.46H20 16S.8L.136H20 3S.2M.1L.34H20... 

Table I compares the chemical and physical properties of two hydroxychromium montmorillonites prepared by reaction of a Na+-exchanged Wyoming montmorillonite (unit cell formula...

A rough estimation of the concentration of potential active sites is often possible from the composition of the catalyst. Thus the maximum value of the concentration of the protonic sites of zeolites, which are active in most of the acid catalysed reactions, can be estimated from the complete unit cell formula of the zeolite (with distinction between framework and extra-framework A1 species). The actual concentration of these sites is often lower (two times or more). 

Table IT. Unit cell formula and crystal parameters of the eiliceoua HFI-type zeolitea (as synthesized and ( > calcined)...

Materials Used. The NaY zeolite and an ion-exchanged form of it, SK-500, were supplied by Union Carbide Corp., Linde Division, in the form of uncalcined powder. The SK-500 (Lot Number 12506-39) is a rare earth-ammonium exchanged type Y zeolite and had not been activated previously or calcined in its preparation. The calculated unit cell formula was... 

Name (Si/Al)ftam. Na (ppm) Unit cell formula NefAl/U.C. 

Figure 1. The hectorite structure, an idealized, unit cell formula being Na0.tr [Lit., Mg,.st](Sig. )0,c(0H,F)t. Key O, oxygen , OH and occasionally fluoride. The tetrahedral sites are occupied mainly by silicon magnesium and lithium occupy the octahedral sites.

Catalyst Unit cell formula Si/Al (%) Exchange Acidity (10 hV) Pore Volume (cmlg ) Micro Meso ... 

The main characteristics of the zeolite samples are given in table 1. Their unit cell formula was drawn fium their elemental analysis and from the number of framework aluminium atoms per unit ceU (NaI) estimated from the relationship between the wavenumber of IR structure bands and NA[. Among the zeolite samples, only HFAU4 and 100 and HBEAIO contained a large amount of extraframework aluminium species. 

Zeolite Unit cell formula Nepal v Vm Nh Nioo... 

The number of protonic acid sites estimated from the unit cell formulas was compared to the number of sites on which ammonia remained adsorbed above 100 C and 300°C. In the FAU and MOR series, the number of ammonia molecules... 

Write the half-unit-cell formula for a montmorillonite mineral with a layer charge of 0.3, with 90° of the substitution in the octahedral layer (Mg2+ for Al3+) and 10% of the substitution in the tetrahedral layer (Al3+ for Si44-). The saturating cation is Na h. Draw a diagram of this mineral, indicating the position of Mg2+, AI3+, Si4+, and Na+... 

Materials. Four different samples with Al/Si ratios ranging from an extreme Y to an extreme X were supplied by the Linde Co., New York. As they constitute a complete substitutional series, the indications X and Y will not be used further but will be replaced by the symbol F followed by the name of the saturating ion and a figure indicating the number of ions per unit cell. In order to ensure complete saturation, the samples as received were treated with a IN NaCl solution and washed free from excess electrolyte. The chemical composition was determined and expressed in terms of unit cell formula, as follows ... 

Catalyst Unit cell formula EFAI Framework Si/AI Crystallinity RX (%)... 

The unit cell formula of HZSM5 determined from the chemical analysis is Hg.oNao.aAla.aSiga.yOiga, which corresponds to a number of protonic sites of 2.1 lO o g-f. All the acid sites are strong indeed the heat of ammonia adsorption is between 80 and 145 kJ mol-i (7) the desorption of NH3 occurs only above 500 K. 

Ideal unit cell formula Cavity Description... 

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