Zeolites, reactions

Hay, R. L., 1966, Zeolites and zeolitic reactions in sedimentary rocks. Geological Society of America Special Paper 85. 

Fig. 2 Effect of Reaction Temperature on Isopropylation Catalyzed by HY Zeolite Reaction conditions HY(5.8) 1 g. Biphenyl 50 mmol, Propene 100 mmol, 4 h.

Figure 3.6 Yields, X (%) of phenyl acetate, PA ( ), o-hydroxyacetophenone, o-HAP (o) and p-hydroxyacetophenone, p-HAP ( ) as a function of the conversion of phenol, Xp (%), in an equimolar mixture with acetic acid over HMFI at 553 K. Reprinted from Journal of Molecular Catalysis, Vol. 93, Neves et al., Acylation of phenol with acetic acid over a HZSM-5 zeolite, reaction scheme, pp. 169-179, Copyright (1994), with permission from Elsevier...

Figure 17. Comparison of ammonia TPD spectra of fresh REY zeolite with that of coked zeolite, reaction catalytic cracking of oil obtained by the pyrolysis of polyethylene.

Figure 3 Effect of water on NO conversion with zeolites. Reaction condition NO 1,000...

Figure 5. Product distribution of n-hexane decomposition over zeolites. (Reaction temperature 723K. Cl methane, C2 ethylene, C2 ethane, C3 propylene, C3 propane, C4 butenes, C4 butanes, C5 pentenes, and C5 pentanes)...

The equations and plots presented in the foregoing sections largely pertain to the diffusion of a single component followed by reaction. There are several other situations of industrial importance on which considerable information is available. They include biomolecular reactions in which the diffusion-reaction problem must be extended to two molecular species, reactions in the liquid phase, reactions in zeolites, reactions in immobilized catalysts, and extension to complex reactions (see Aris, 1975 Doraiswamy, 2001). Several factors influence the effectiveness factor, such as pore shape and constriction, particle size distribution, micro-macro pore structure, flow regime (bulk or Knudsen), transverse diffusion, gross external surface area of catalyst (as distinct from the total pore area), and volume change upon reaction. Table 11.8 lists the major effects of all these situations and factors. 

Cundy, Cox 2005 Hydrothermal synthesis of zeolites reaction mechanism [50]... 

Figure 18. Evolution of high-resolution low-power 13C-NMR spectra of 2-13C-isopropanol adsorbed on K- and Cs-ZSM-5 zeolites. Reaction temperature 200 "C, measuring temperature 25 C. (Reproduced with permission from ref. 68. Copyright 1985 Elsevier.)...

Typical reaction in this category is the conversion of limonene to P-cymene over Pd-H-borosilicalite where isomerization is followed by dehydrogenation. Also many reactions mentioned here, particularly catalyzed by transition metal ion or bimeallic, are bifunctional zeolitic reactions. 

Neves, L, Jayat, R, Magnoux, R, Perot, G., Riberito, R R., Guberlmarm, M., and Guisnet, M. 1994. Acylation of phenol with acetic acid over a HZSM5 zeolite, reaction scheme. /. Mol. Catal. 93 169-179. 

Interstitial water has an important effect on zeolitic reactions in sedimentary rocks (4, 6). Zeolitic tuffs of 3 drillings originally were saturated with sea water. The chlorinity of interstitial water in cores is generally lower than that of sea water (8, 9), and tends to decrease with increasing depth of burial, although the rate of decrease is higher in mudstone than in sandstone (Figure 5). The chlorinity in tuffs shows relationships similar to that in the normal clastic sediments. Analcime may replace clinoptilolite or mordenite in water with much lower chlorinity than sea water. 

In a typical experiment of the chloromethane/zeolite reaction on the ZSM-5 catalyst chloromethane converion varies from 98.5% to 100%. Over 240 compounds have been analytically separated from the reaction mixture and about 90% of the products have been identified. 1,2,4-trimethylbenzene is a major product, which constitutes about 45 wt% of the total liquid product. Tetra- and penta-methylbenzenes are also found but in substantially lower amounts. A few percent of the products contain chlorine, which are mostly 2-chloroalkanes presumably formed by Markovnikov addition of HCl to the terminal olefins, both being produced in... 

Interesting kinetic information of the importance of adsorption effects to overall kinetics of a zeolitic reaction is obtained by studying the reaction at conditions where pore filling varies . Experimental data indicate that especially the orders of alkane and hydrogen are sensitively dependent on this. Whereas at high pressures pores are completely filled and hence in a bifimctional mechanism alkane and alkene are equilibrated within the micropore , this is not necessarily the case at low pressures. 

Zeolitization reactions have been found to predominate in the low-temperature hydrothermal reactions of metakaolinite, Al2Si207. The reactions have been carried out with and without additions of silica by use of bases LiOH, NaOH, RbOH, and CsOH and also the mixtures NaOH + LiOH, NaOH + KOH, KOH + LiOH, and NaOH -I- Me4NOH. The zeolites produced, which have been characterized by a number of physicochemical techniques, have been listed in the section on aluminosilicates (Table 40). The synthesis of the zeolites Linde A and faujasite has been studied using phosphorescence spectroscopy and laser Raman spectroscopy the results obtained were indicative of a zeolite crystallization in the solid gel phase via condensation between hydroxylated Si— Al tetrahedra. 

Cations (12), related dications, and cations (13) were obtained as stable salts and characterized by various spectral properties and X-ray structure determination. The reactivity of diarylmethyl cations in non-protic zeolites was studied. Comparison with solution reactivities shows a significant decrease in sensitivity to substiment in the zeolite. This is explained through a low isokinetic temperature for the zeolite reaction. 

FROM CROWN ETHERS TO ZEOLITES REACTION OF EtAICl2 WITH CROWN ETHERS... 

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