Benzylation of benzene by benzyl chloride over iron mesoporous molecular sieves materials (original) (raw)
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Catalytic activity of mesoporous catalysts in Friedel–Crafts benzylation of benzene
2009
Different samples of metal-incorporated MCM-41 were prepared and used as catalysts in Friedel-Craft's benzylation of benzene. The catalytic performance was evaluated by off-line GC analysis. Fe-MCM-41 exhibited excellent activity, the sample with Si/Fe ratio = 10 showed 90% conversion with 95% selectivity towards diphenylmethane within a few minutes. Generally, the activity per Fe-site was an order of magnitude higher for the samples containing a combination of Fe 2 O 3 nano-particles and isolated Fe 3+ sites. A synergy of two catalytic centers (particles and isolated sites) is proposed to explain the high performance of the highly loaded samples. The catalytic performance of Fe-MCM-41 was superior to other metalcontaining MCM-41 (e.g. Ga, Sn, and Ti) catalysts, or other Fe-containing mesoporous materials (e.g. Fe-HMS).
Journal of Molecular Catalysis A: Chemical, 2007
Iron-containing aluminophosphate molecular sieves were synthesized in AEL and AFI structure types by static hydrothermal crystallization. These materials have been characterized by elemental analysis, X-ray diffraction, scanning electron microscopy, N 2 adsorption-desorption, temperature programmed desorption of ammonia (NH 3 -TPD), and 57 Fe Mössbauer spectroscopy. Alkylation of benzene and other aromatics by benzyl chloride has been investigated over these solids. Indeed, the iron containing microporous aluminophosphates showed both high activity and high selectivity for this reaction. The activity of these catalysts for the benzylation of different aromatic compounds is in the following order: benzene > toluene > pxylene > anisole. More interesting is the observation that this catalyst can be reused in the benzylation of benzene for several times. Kinetics of the benzene benzylation over these catalysts has also been investigated.
Unique Catalytic Activity of Mesoporous Catalysts in Friedel-Crafts Benzylation of Benzene
Different samples of metal-incorporated MCM-41 were prepared and used as catalysts in Friedel-Craft's benzylation of benzene. The catalytic performance was evaluated by off-line GC analysis. Fe-MCM-41 exhibited excellent activity, the sample with Si/Fe ratio = 10 showed 90% conversion with 95% selectivity towards diphenylmethane within a few minutes. Generally, the activity per Fe-site was an order of magnitude higher for the samples containing a combination of Fe 2 O 3 nano-particles and isolated Fe 3+ sites. A synergy of two catalytic centers (particles and isolated sites) is proposed to explain the high performance of the highly loaded samples. The catalytic performance of Fe-MCM-41 was superior to other metalcontaining MCM-41 (e.g. Ga, Sn, and Ti) catalysts, or other Fe-containing mesoporous materials (e.g. Fe-HMS).
Benzylation of benzene and other aromatics by benzyl chloride over mesoporous AlSBA-15 catalysts
Microporous and Mesoporous Materials, 2005
Aluminum-containing mesoporous molecular sieves AlSBA-15 with different n Si /n Al ratios and AlMCM-41 have been synthesized hydrothermally and characterized in detail by physicochemical methods, viz. XRD, N 2 adsorption and 27 Al NMR spectroscopy. The low angle XRD and N 2 adsorption measurements reveal that the structural order of SBA-15 was retained after the incorporation of Al. The increase of the unit cell parameter with increasing aluminum content and 27 Al MAS NMR spectroscopy confirm the incorporation of aluminum in the framework. Benzylation of benzene and substituted benzenes reaction employing benzyl chloride as the alkylating agent over AlSBA-15 and AlMCM-41 have been investigated. The influence of various reaction parameters such as reaction temperature, reactant feed ratio and catalyst amount affecting the activity and selectivity of AlSBA-15, have been studied. Among the mesoporous catalysts studied, , where the number in parentheses indicates the molar n Si /n Al ratio, shows both high conversion and high selectivity for the benzylation of benzene. The activity of this catalyst for the benzylation of different aromatic compounds is in the following order: benzene > toluene > p-xylene > mesitylene > anisole. Kinetics of the benzene benzylation over different catalysts have also been investigated.
Journal of Molecular Catalysis A: Chemical, 2006
The benzylation of benzene by benzyl chloride to diphenylmethane over FeCl3, InCl3, GaCl3, ZnCl2, CuCl2 and NiCl2 supported on mesoporous SBA-15 at 353K has been investigated. The redox property due to the impregnation of the SBA-15 by transition metal chloride seems to play a very important role in the benzene benzylation process. Among the catalysts, the FeCl3/SBA-15 showed both high conversation and high selectivity for the benzylation of benzene. The activity of these catalysts for the benzylation of different aromatic compounds is in the following order: benzene>toluene>p-xylene>anisole. More interesting is the observation that this catalyst is always active and selective for large molecules like naphthenic compounds such as methoxynaphthalene and he can also be reused in the benzylation of benzene for several times. Kinetics of the benzene benzylation over these catalysts have also been investigated.
Green Synthesis of Benzylated Aromatics Using Iron Loaded Mesoporous Materials
E-Journal of Chemistry
Syntheses of benzylated aromatics like diphenylmethane and its derivatives by the condensation of benzene or toluene or o-xylene with benzylchloride or 4-methylbenzylchloride in the presence of a catalytic amount of various iron loaded mesoporous solid acid catalysts such as Fe/Al-MCM-41 (Si/Al=25), Fe/Al-MCM-41 (Si/Al=50) and Fe/Al-MCM-41 (Si/Al=100) are reported.
Microporous and Mesoporous Materials, 2008
Three-dimensional cage type ferrosilicate catalysts with different nSi/nFe ratios (FeSBA-1(x) where x denotes the nSi/nFe molar ratio) have been prepared at a molar hydrochloric acid to silicon ratio of 10 using cetyltriethylammonium bromide as the template. The obtained materials have been unambiguously characterized by XRD, N2 adsorption, and ESR spectroscopy, and their catalytic activity in the benzylation of benzene and the substituted benzene has also been investigated. The catalytic results of the FeSBA-1 catalysts with different nSi/nFe ratios have been compared with the uni-dimensional FeSBA-15, AlSBA-15 and FeHMS catalysts. It has been found that the activity of the FeSBA-1 catalysts is much higher as compared to that of the FeSBA-15, FeHMS and AlSBA-15 catalysts. The activity of the catalysts declines in the following order: FeSBA-1(36) > FeSBA-1(90) > FeSBA-1(120) > FeSBA-1(344) > FeSBA-15(152) > FeHMS(50) > AlSBA-15(45). The effect of various reaction parameters such as reaction time, reaction temperature, reactant feed ratio and the various electron donating groups on the benzene ring affecting the activity and selectivity of FeSBA-1(344) have also been studied. The catalysts are highly active and show a complete conversion of benzyl chloride and a clean selectivity to diphenylmethane (DPM) within a short period of time under the optimized reaction conditions. The reaction kinetics of the catalysts has been extensively investigated and the results are presented. The apparent rate constant of the FeSBA-1(344) and the BC conversion sharply increase with increasing the reaction temperature. The activity of the FeSBA-1(344) catalyst for the benzylation of different aromatic compounds is in the following order: benzene > anisole > mesitylene > p-xylene > toluene.
Aluminum chloride grafted mesoporous molecular sieves as alkylation catalysts
Microporous and Mesoporous Materials, 2005
The aim of this work is to study the influence of different mesoporous molecular sieves (MMSs) type and the effect of pore diameter on MMSs silica grafted aluminum chloride catalysts and their activity in benzene alkylation by 1-dodecene. Four samples (two hexagonal and two wormhole like structures with different pore diameters) were prepared by post-synthesis grafting reaction in moisture free conditions (Schlenk technique). The physico-chemical properties were monitored by N 2 adsorption, XRD, atomic adsorption, 29 Si and 27 Al MAS NMR. Acidity data were obtained by TPD of ammonia, and FTIR of adsorbed pyridine. The alkylation of benzene is carried out in a Schlenk tube under dry conditions at room temperature. The products were analyzed by GC-MS. Grafting aluminum chloride on MMSs increases the yield of monoalkylated products.