Molecular sieves silicates

Figure 8-4. Molecular sieve silicate MCM-41. Left Structure of hexagonal pores with 3.1-nm diameter. Right Model of the incorporation of 1 (R = -0-CH2-CH2-N (013)3 M = Zn(II) in the columnar orientated detergent cetyltrimethylammonium chloride surrounded by the MCM-41 chaimels.

Monsalvo and Shapiro (2007a) carried out an extensive comparison of MPTA (using two different equations of state for the fluid-fluid interactions) and lAST. They considered the adsorption of 40 binary gas systems (more than 600 points) on activated carbon, molecular sieves, silicates and silica gels as well as eight ternary gas systems with about 120 data points on the same type of solids. They reported results both in terms of adsorption equilibria (mole fractions, x) and, when possible, also for total adsorbed amounts (n). For the binary systems, the average % deviation with MPTA is 5 and 9 (over the whole database, respectively forx.n) and 5 and 7 for lAST (x,n). For the ternary systems, the deviations are higher but nevertheless similar with the two approaches (around 11-12 for both MPTA and lAST here the differences in the model performance for adsorption equdibria... 

Physical Properties. Physical properties of importance include particle size, density, volume fraction of intraparticle and extraparticle voids when packed into adsorbent beds, strength, attrition resistance, and dustiness. These properties can be varied intentionally to tailor adsorbents to specific apphcations (See Adsorption liquid separation Aluminum compounds, aluminum oxide (alumna) Carbon, activated carbon Ion exchange Molecular sieves and Silicon compounds, synthetic inorganic silicates). 

TS-1 (titanium silicate molecular sieve), H2O2, MeOH, reflux, 4-18 h, 60-64% yield. ... 

Zeolites are naturally occurring hydrous aluminum-sodium silicates in porous granule form. They are capable of exchanging their sodium base for calcium or magnesium and of expelling these alkaline earth metals for sodium by treatment with salt. Thus, they are a type of ion-exchange media. (Some zeolites act as molecular sieves by adsorption of water and polar compounds.)... 

Today n-paraffms are exclusively produced from the corresponding distillation cuts of paraffin-rich oils with the use of molecular sieves. Molecular sieves are synthetically manufactured aluminum silicates of the zeolite type, which after dehydration have hollow spaces of specific diameters with openings of specific diameters. The molecules are then able to penetrate the openings in the correct size and form and are held in the hollow spaces by electrostatic or van der Waals forces. The diameter of the zeolite type used for the production of paraffins is 5 A and is refined so that the n-paraffins (C5-C24) can penetrate the hollow spaces while the iso- and cyclic paraffins are unable to pass through [15]. 

After the submission of this contribution, a remarkable review authored by Ratnasamy, Srinivas and Knozinger has appeared on the investigation, by means of both experimental and theoretical methods, of the active sites and reactive intermediates in titanium silicate molecular sieves [126]. 

A fascinating area is micellar autocatalysis reactions in which surfactant micelles catalyse the reaction by which the surfactant itself is synthesized. Thus synthesis of dimethyldoceylamino oxide (reaction between dimethyl dodecyl amine and H2O2) benefits from this strategy. Here an aqueous phase can be used and an organic solvent can be avoided. Synthesis of mesoporous molecular sieves benefit through micellar catalysis and silicate polymerization rates have been increased by a factor 2000 in the presence of cetyltrimethyl ammonium chloride (Rathman, 1996). 

Naturally occurring hydrated silicates of calcium and aluminium the name is also given to synthetic substances with a similar crystalline structure used as the basis of molecular sieves. ZEPC... 

In a sorption pump, the gas is trapped within the adsorbing material (zeolites or active charcoal) called molecular sieve. Zeolites are porous aluminium silicates which adsorb large amount of gas when cooled to low temperature (usually 77K). The pump is filled with zeolite and put in a bucket containing liquid nitrogen (see Fig. 1.11). 

Active Sites and Reactive Intermediates in Titanium Silicate Molecular Sieves... 

Appendix C. Synthesis of Titanium Silicate Molecular Sieves. 143... 

TS-1 and TS-2 microporous titanium silicate molecular sieves with MFI... 

ETS-4 and ETS-10 Engelhard Corporation titanium silicate molecular sieves... 

The main objective of this review is to summarize and critically analyze recent advances made in the characterization and catalytic properties of titanium silicate molecular sieves after the reviews of Notari (33) and Vayssilov (34) in 1996 and 1997, respectively. Of special interest are... 

V.C. Epoxidation on Titanium Silicate Molecular Sieves V.C.l. General Features of Epoxidations... 

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