Suman K. Jana

Alkylation of benzene by benzyl chloride over H-ZSM-5 zeolite with its framework Al completely or partially substituted by Fe or Ga

Liquid-phase benzylation of benzene by benzyl chloride to diphenylmethane over H-ZSM-5, H-gallosilicate(MFI), H-galloaluminosilicate(MFI), H-ferrosilicate(MFI) and H-ferroaluminosilicate(MFI) zeolites at 80°C has been investigated. A complete or partial substitution of Al in H-ZSM-5 zeolite by Fe or Ga results in a drastic increase in the catalytic activity of the zeolite in the benzylation process. The redox function of the zeolite is relatively more important than its acid function in the benzylation process.

Benzylation of benzene by benzyl chloride over Fe-, Zn-, Ga-and In-modified ZSM-5 type zeolite catalysts

Liquid phase benzylation of benzene by benzyl chloride to diphenylmethane over H-ZSM-5, H-gallosilicate (MFI), H-galloaluminosilicate (MFI), H-ferrosilicate (MFI), H-ferroaluminosilicate (MFI), Fe 2 O 3 /H-ZSM-5, ZnO/H-ZSM-5, Ga 2 O 3 /H-ZSM-5 and In 2 O 3 /H-ZSM-5 zeolites (at 60 and 80°C) has been investigated. A complete or partial substitution of Al in H-ZSM-5 zeolite by Fe or Ga or an impregnation of the zeolite by Fe 2 O 3 , ZnO, Ga 2 O 3 or In 2 O 3 makes the zeolite highly active in the benzylation process. The redox function created due to the modification of the H-ZSM-5 zeolite by Fe, Zn, Ga or In seems to play very important role in the benzylation process. However, all these catalysts show a significant induction period for the reaction. The Ga 2 O 3 /H-ZSM-5 catalyst showed high benzene benzylation activity even in the presence of moisture in the catalyst and/or in the substrate. However, the reaction induction period is increased markedly with increasing the moisture and it is reduced by removing the moisture from the catalyst by refluxing with moisture-free benzene. It is also reduced by the HCl gas pretreatment to the catalyst before the benzylation reaction. The Ga 2 O 3 /H-ZSM-5 and In 2 O 3 /H-ZSM-5 catalysts showed excellent reusability in the benzene benzylation. Kinetics of the benzene benzylation (using an excess of benzene) over the H-GaMFI, H-GaAlMFI, H-FeMFI, Ga 2 O 3 /H-ZSM-5 and In 2 O 3 /H-ZSM-5 catalysts have also been thoroughly investigated. A plausible reaction mechanism for the reaction over the modified ZSM-5 zeolite catalysts is proposed.

Solvent-Free Selective Oxidation of Benzyl Alcohol and Benzaldehyde by tert-Butyl Hydroperoxide Using MnO-4-Exchanged Mg–Al–Hydrotalcite Catalysts

MnO-4 (0.4 mmol/g)-exchanged Mg-Al-hydrotalcite is an active and highly selective catalyst for the oxidation of benzyl alcohol to benzaldehyde by tert-butyl hydroperoxide under reflux in the absence of solvent. It also shows high activity for the oxidation of benzaldehyde to benzoic acid. The higher the Mg/Al ratio, the higher is the catalytic activity (in both the reactions) and basicity of the hydrotalcite catalyst.

Friedel-Crafts type benzylation and benzoylation of aromatic compounds over Hβ zeolite modified by oxides or chlorides of gallium and indium

Liquid phase benzylation (by benzyl chloride) and benzoylation (by benzoyl chloride) of benzene and other aromatic compounds over different Ga- and In-modified Hb zeolite catalysts at 80 � C have been investigated. An impregnation of the zeolite by oxides or chlorides of Ga and In makes the zeolite highly active in the benzylation process but it results in a decrease in the acidity, particularly the strong acid sites (measured in terms of the ammonia chemisorbed at 250 � C) of the zeolite. Both the redox function, created due to the modification of the Hb zeolite by Ga or In, and the zeolitic acidity seem to play important role in the benzylation or benzoylation process. Among the different Ga- and In-modified Hb zeolite catalysts, the In2O3/Hb showed highest activity for the benzene benzylation. This catalyst also showed high activity for both the benzylation and benzoylation of other aromatic compounds, even in the presence of moisture in the reaction mixture; in case of the benzoylation, the moisture has beneficial effect. The In2O3/Hb catalyst can be reused in the benzylation for several times. Kinetics of benzene benzylation (using excess of benzene) over the different Ga- and Inmodified Hb zeolite catalysts has also been investigated. A plausible mechanism for the activation of both the reactants (aromatic substrate and benzyl or benzoyl chloride, forming corresponding carbocation) over the catalyst and also for the reaction between the carbocation and the activated and/or non-activated aromatic substrate is proposed. � 2002 Elsevier Science Inc. All rights reserved.

Benzylation of benzene by benzyl chloride over Fe-modified ZSM-5 and H-β zeolites and Fe2O3 or FeCl3 deposited on micro-, meso- and macro-porous supports

Abstract A number of Fe-containing solid catalysts, such as Fe-modified ZSM-5 type zeolites (Fe 2 O 3 /H-ZSM-5, SO 4 2− /Fe 2 O 3 /H-ZSM-5, H-FeMFI and H-FeAlMFI), Fe-modified H-β zeolites (Fe 2 O 3 /H-β and SO 4 2− /Fe 2 O 3 /H-β), Fe 2 O 3 supported on meso-porous Si-MCM-41, silica gel or macro-porous silica–alumina commercial catalyst carrier (SA-5205), and FeCl 3 impregnated on 13X zeolite, Si-MCM-41, silica gel or commercial clays––montmorillonite K10 (Mont K10) or kaolin, have been compared for their performance in the benzylation of benzene by benzyl chloride (80 °C). Among these catalysts, the Fe 2 O 3 /H-β (or H-ZSM-5) and FeCl 3 /Mont K10 (or Si-MCM-41) are found to be highly promising ones for the benzylation, even in the presence of moisture. These catalysts can also be reused in the reaction but with reduced activity. No direct relationship is observed between the acidity (measured in terms of ammonia chemisorbed at 50 or 200 °C) and the benzylation activity of the catalysts. The benzylation activity is controlled mainly by the redox properties of the catalyst. The selectivity for diphenyl methane in the benzylation was found to vary from catalyst to catalyst.

Acylation of aromatic compounds using moisture insensitive InCl3 impregnated mesoporous Si-MCM-41 catalyst

Abstract Acylation of aromatic compounds (benzene, toluene, p -xylene, mesitylene, anisole, naphthalene, methylnaphthalene and methoxynaphthalene) by an acyl chloride (benzoyl chloride, phenylacetyl chloride, propionyl chloride or butyryl chloride) in high yield, in a short reaction period (3 h), even in the presence of moisture in the aromatic substrate or solvent (dichloroethane), can be accomplished at low temperature (80±1°C) using an InCl 3 impregnated Si-MCM-41 catalyst in low catalyst concentration.

Aluminum incorporation in mesoporous MCM-41 molecular sieves and their catalytic performance in acid-catalyzed reactions

Abstract Mesoporous aluminosilicate molecular sieves, Al-containing MCM-41, with different Si/Al ratios were synthesized by four different methods: sol–gel, hydrothermal, template cation exchange and grafting. The catalysts prepared by sol–gel, grafting and template cation exchange methods are effective for the incorporation of large amounts of aluminum into the framework of MCM-41. The catalytic activities of the resulting Al-containing MCM-41 samples were tested in the cracking of cumene and the dehydration of 2-propanol, as model acid-catalyzed reactions, and then compared with the results obtained from microporous H-ZSM-5 and HY zeolites. The Al-containing MCM-41 catalysts prepared by different methods behaved differently in acting as acidic catalysts; the catalyst (having almost same Si/Al ratio) prepared by sol–gel method showed higher cracking activity, whereas that prepared by template cation exchange method showed higher dehydration activity. Moreover, these Al-containing MCM-41 catalysts are more catalytically active than microporous HY zeolite for cumene cracking and 2-propanol dehydration reactions.

Highly active and moisture‐insensitive solid catalysts – GaCl3 and InCl3 supported on montmorillonite‐K10 and Si‐MCM‐41 for benzylation of benzene

InCl3 and GaCl3 supported on montmorillonite‐K10 or on high silica mesoporous MCM‐41 show very high activity in the benzylation of benzene by benzyl chloride (at 80°C) with little or no effect in the presence of moisture in the catalyst or in the reaction mixture on their benzylation activity; the supported InCl3 catalyst shows superior performance in the benzylation reaction in regard to both the activity and moisture insensitivity.

Progress in Pore-Size Control of Mesoporous MCM-41 Molecular Sieve Using Surfactant Having Different Alkyl Chain Lengths and Various Organic Auxiliary Chemicals

Pore-size control of mesoporous silica MCM-41 molecular sieve is described on the basis of the use of surfactant having different alkyl chain lengths and various organic auxiliary chemicals during the hydrothermal synthesis process. The BJH pore diameter of MCM-41 can be tuned from 1.6 to 4.2 nm using single or mixture of two surfactant(s) with alkyl chain lengths varied from C8 to C22. By the addition of different organic auxiliary chemicals: 1,3,5-trimethylbenzene, isopropylbenzene or tridecane into the synthesis medium, the BJH pore size of MCM-41 can be tailored up to 12.0 nm.

Acylation of aromatic alcohols and phenols over InCl3/montmorillonite K-10 catalysts

Montmorillonite K-10 clay supported InCl3 is a highly active catalyst for the acylation of aromatic alcohols and phenols with different acyl chlorides. This catalyst can be reused in reactions a number of times without very significant loss of catalytic activity