Formation in Zeolites

Dimethyl ether, 31 41, 244 formation in zeolites, 42 95-98 Dimethylethylbenzenes, 20 281 Dimethylindan, cyclization, 28 298, 299 Dimethylindene, cyclization, 28 298, 299 Dimethyl methyl phosphonate, catalytic decomposition, 35 159-160 Dimethylnaphthalenes, hydrogenation of, 18 64-102... 

Li, C. and Stair, P.C. (1997) Ultraviolet Raman spectroscopy characterization of coke formation in zeolites. Catalysis Today, 33 (1-3), 353-60. 

Organic and inorganic radical formation in zeolites can occur spontaneously, on adsorption of molecules into a suitably activated zeolite, or as the result of radiolysis of adsorbed species. Once a radical is formed, EPR spectroscopy can be used to follow its subsequent reactions. For example, Trifunac et al have recently described the use of variable temperature EPR to investigate reactions of olefin radical cations generated in ZSM-5 zeolites. [4]. This work shows clearly the facile rearrangement of radical cations produced by irradiation of... 

L. D. Rollman and D. E. Walsh, Shape Selectivity and Carbon Formation in Zeolites, Journal of Catalysis 56 139-140 (1979). 

P-10 - Effects of synthesis parameters on intra-pore zeolite formation in zeolite A membranes... 

Early simulation studies of internal coke formation in zeolites indicate that the coke would (at least initially) form in the chatmel intersections or cavities rather than in the channels themselves [13]. Recently, Guisnet and coworkers[2] have confirmed the importance... 

In this case, the process for the production of gasoline from methanol is considered. One of the critical problem in the development of this process is the deactivation of the zeolite catalyst used via coke formation. This deactivation by coke formation in zeolites has been simulated by Guo et al. [12] using a site-bond-site modefwith a two dimensional square lattice. The effect of gaseous pressure on the coke formation was foimd to be similar to that reported in the literature. The authors have not compared their results with kinetic data. 

Rollmann, Louis D. and Walsh, Dennis E. (1982) Constraints on carbon formation in zeolite catalysts, in J.L. Figuereido (ed.), Progress in Catalyst Deactivation, NATO AS I Series E, Martinus Nijhoff Publishers, The Hague, pp. 81-91. 

Platinum carbonyls stable under normal conditions are practically unknown, but their formation in zeolites has been detected [293, 294]. 

On the other hand, the fact that many metal carbonyl clusters are colored [80] often allows thdr formation in zeolite cages to be qualitatively monitored visually. The color of a zeolite which contains a duster may not be quite the same as that of the duster in the pure solid state. For example, [Ir4(CO)i2] in NaY zeolite is yellow, a odor almost the same as that of the cluster in solution. [3, 5, 66] The color of the [Ir (CO)ig] isomer with edge bridging CO ligands in a NaY zeolite is yellow, [3, S] but the color of this duster in tetrahydrofuran solution is red. [57, 58]... 

Lercher JA, Santen RA, Vinek H (1994) Carbonium ion formation in zeolite catalysis. Catal Lett 27(l) 91-96... 

The phenomenon of shape selectivity in the reactions performed on zeolites arises from the fact that the probabilities of forming various products in the narrow intracrystalline cavities and channels are largely determined by the dimension and configuration of the zeolite pores [163], Although there was extensive indirect evidence of the shape selectivity of catalysis by zeolites [164,165], there was no direct observation of this effect based on analysis of the reaction products inside the pores. The ability of MAS NMR to identify the structure of organic molecules directly in the intracrystalline voids of zeolites allowed direct observation of the shape selectivity effect. Anderson and Klinowski analyzed the products of methanol conversion into gasoline on zeolite ZSM-5 by in situ C MAS NMR and reliably established the formation in zeolite pores of a number of methyl-substituted benzenes that had never been observed at the reactor outlet [166], The origin of this effect was obvious (Scheme 6) different trimethylbenzenes are formed in the zeolite pores, however, the bulkiest isomers cannot leave the pore interior because of the limited pore exit size in the zeolite structure. Thus, the... 

Rollmann LD, Walsh DE. Shape selectivity and carbon formation in zeolites. J Catal 1979 56 139-40. 

---