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Friedel zeolite beta

The present work reports the results obtained in the Friedel-Crafts acylation of different aromatic substrates catalyzed by zeolite Beta obtained according to a novel method based on the crystallization of silanized seeds, as a way to perturb the subsequent crystal growth step and to modify the zeolite textural properties [5], The catalytic behavior of this material is compared with that of the conventional Beta zeolite. [Pg.337]

A conclusion of early studies is that zeolite Y and zeolite Beta are the most promising catalysts for Friedel-Crafts acylation. This is attributed to their large pores,... [Pg.412]

Acid catalysts are used to promote the alkylation of ethylene to benzene. Acid catalysts suitable for benzene alkylation include protonic acids (i.e., H2SO4, HF, and H3PO4), Friedel-Crafts catalysts (i.e., AICI3 and BF3), and more recently, solid acid catalysts. Solid acid catalysts used for the commercial manufacture of EB are typically zeolitic molecular sieves and materials such as ZSM-5, faujasite, MCM-22, and zeolite beta. Zeolites physical and chemical properties can be modified to optimize the activity, selectivity, and stability of the catalysts. This flexibility of zeolites has made them the preferred catalyst of choice. [Pg.931]

V.F.D. Alvaro, A.F. Brigas, E.G. Derouane, J.P. Louren, B.S. Santos, Mild liquid-phase Friedel-Crafts acylation of heteroaromatic compounds over zeolite Beta, J. Mol. Catal. A Chem. 305 (2009) 100-103. [Pg.407]

Catalytic activity of the beta zeolite with enhanced textural properties in the Friedel-Crafts acylation of aromatic compounds... [Pg.337]

Friedel-Crafts acylation is widely used for the production of aromatic ketones applied as intermediates in both fine chemicals and pharmaceutical industries. The reaction is carried out by using conventional homogenous catalysts, which represents significant technical and environmental problems. The present work reports the results obtained in the Friedel-Crafts acylation of aromatic substrates (anisole and 2-methoxynaphthalene) catalyzed by Beta zeolite obtained by crystallization of silanized seeds. This material exhibits hierarchical porosity and enhanced textural properties. For the anisole acylation, the catalytic activity over the conventional Beta zeolite is slightly higher than with the modified Beta material, probably due to the relatively small size of this substrate and the weaker acidity of the last sample. However, the opposite occurred in the acylation of a bulky substrate (2-methoxynaphthalene), with the modified Beta showing a higher conversion. This result is interpreted due to the presence of a hierarchical porosity in this material, which favors the accessibility to the active sites. [Pg.337]

Keywords Friedel-Crafts acylation, Beta zeolite, hierarchical zeolites. [Pg.337]

Hardacre et al. report the Friedel-Crafts benzoylation of anisole with benzoic anhydride to yield 4-methoxybenzophenone with various ILs and zeolite catalysts (USY, HZSM-5, H-beta, and H-mordenite). The rates of reaction were found to be significantly higher using ionic liquids compared with organic solvents.Continuous-flow studies of successful ionic liquid systems indicate that the bulk of the catalysis is due to the formation of an acid via the ion exchange of the cation with the protons of the zeolite as shown in the following reaction. Scheme 8. [Pg.165]

Another well known example of successful application of Beta zeolite is the substitution of AICI3 for Friedel-Crafts acylation. This reaction is an important industrial process, used for the preparation of various pharmaceuticals, agrochemicals and other chemical products, since it allows us to form a new carbon-carbon bond onto an aromatic ring. Friedel-Crafts acylations generally require more than one equivalent of for example, AICI3 or BF3. This is due to the strong complexation of the Lewis acid by the ketone product. [Pg.132]

For example, the Friedel-Crafts-acylation of anisole with acetic anhydride with the acidic zeolite H-beta leads to p-methoxyacetophenone in fixed-bed operation (Eq. 8-26). Compared with the traditional process, using more than one equivalent of AICI3 (Eq. 8-27), the number of unit operations could be reduced from 12 to 2 by Rhone-Poulenc. [Pg.291]

Previously, Kantam et al. also carried out the Friedel-Crafts acylation of pyrrole with acetic anhydride over microcrystalline beta zeolites with less successful results [118]. The microcrystalline beta zeolite catalysts showed the highest activity in the acylation reaction due to their higher acidity as compared with ordinary beta zeolite. When a microcrystalline beta zeolite I (with a particle size of 1-10 gm obtained by mechanical disintegration of beta zeolite) was used as catalyst, 73% of conversion and 58% of selectivity to 2-acetylp5n role was reached after 2.5 h of reaction time. However, when a microcrystalline beta zeolite II (with a particle size of 10-50 gm obtained by decreasing the aging time to 48 h instead of 1 week) was used, 78% of conversion and 64% of selectivity to 2-acetylpyrrole was reached after 2h of reachon time. [Pg.394]


See other pages where Friedel zeolite beta is mentioned: [Pg.42]    [Pg.194]    [Pg.10]    [Pg.56]    [Pg.103]    [Pg.62]    [Pg.68]    [Pg.145]    [Pg.244]    [Pg.407]   
See also in sourсe #XX -- [ Pg.10 ]




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