Zeolites H-BEA

Figure 4.30 Overlay of IR spectra during CO adsorption at 90 K on H-BEA zeolite. The diagonal arrows indicate whether the band is increasing or decreasing with increasing CO coverage.

Busco, C., Barbaglia, A., Broyer, M., Bolis, V., Foddanu, G.M., and Ugliengo, P. (2004) Charaderization of Lewis and Bronsted addic sites in H-MFI and H-BEA zeolites a thermodynamic and ab initio smdy. Thermochim Acta, 418, 3-9. 

The Fries rearrangement of PA over H-BEA zeolites, which is a simple reaction, was chosen to introduce the competition for adsorption on the zeolite catalysts and its role on the reaction rate. Ortho- and para-hydroxyacetophenones (o- and p-HAP), para-acetoxyacetophenone (p-AXAP) and phenol (P) are the main products o-HAP, P and p-AXAP, which are directly formed (primary products),... 

Figure 2.5 Relative occupancy (%) of the intracrystalline volume of a H-BEA zeolite during the transformation of a 2 1 molar anisole - acetic anhydride mixture in a batch reactor, assuming no adsorption of acetic acid and full occupancy of the micropores. Anisole ( ), acetic anhydride (o) and 4-methoxyacetophenone (x). Reprinted from Journal of Catalysis, Vol. 187, Derouane et al., Zeolite catalysts as solid solvents in Fine Chemicals synthesis 1. Catalyst deactivation in the Friedel-Crafts acetylation of anisole, pp. 209-218, copyright (1999), with permission from Elsevier...

Adsorption experiments The method developed for the analysis of carbonaceous compounds formed and trapped within the zeolite micropores during catalytic reactions1581 can be adapted for determining the occupancy of micropores by reactant, solvent and product molecules. However, this method cannot be used with compounds sensitive to hydrolysis, such as AA, because of the step of dissolution of the zeolite in a hydrofluoric acid solution necessary for the complete recovery of the organic molecules located within the zeolite micropores.[58] This method was used to determine the composition of the organic compounds retained within the micropores of three different zeolites [H-BEA (zeolite Beta), H-FAU (zeolite Y), and H-MFI (zeolite ZSM-5)] after contact in a stirred batch reactor at 393 K for 4 min of a solution containing 20 mmol of 2-methoxynaphthalene (2-MN), 4 mmol of l-acetyl-2-methoxynaphthalene (1-AMN) and 1 ml of solvent (sulfolane or nitrobenzene) with 500 mg of activated zeolite.[59 61] From the comparison of... 

Figure 3.1 Acetylation at 373 K with acetic anhydride of a series of aromatic compounds over HBEA-15 zeolite. Conversion (XSUB) of anisole ( ), 2-methoxynaphthalene (x), m-xylene ( ), toluene ( ), 2-methylnaphthalene (o) and fluorobenzene (a) versus time. Reprinted from Journal of Catalysis, Vol. 230, Guidotti et al. Acetylation of aromatic compounds with H-BEA zeolite the influence of the substituents on the reactivity and on the catalyst stability, pp. 375-383, Copyright (2005), with permission from Elsevier...

In the years since 1998, some papers have reported the benzoylation of substituted benzene derivatives, such as toluene, [9-11] ethyl benzene,[11] xylene,19 11 121 anisole/9 131 dimethoxybenzene,[14] biphenyl/151 phenol[16] and chlorobenzene1171 in the presence of zeolites and, in most cases, particularly H-BEA zeolite. 

Scheme 4.2 Benzoylation of o-xylene to 3,4-dimethylbenzophenone with benzoyl chloride over H-BEA zeolite.

For phenylbenzoate, the relatively more constrained H-BEA zeolite shows a much higher selectivity and an improved 4-HPB/2-HPB ratio (p/o = 2.1). Such a... 

Benzoylation of benzene and other aromatic compounds by benzoyl chloride over H-BEA zeolite modified by indium oxides has been investigated.191 We report in Table 4.2 the time required for half reaction (L/2) f°r a series of aromatic substrates used in the above reaction. The benzoylation reaction rate (via L /2 value) depends strongly on the substituent group present in the aromatic substrate and increases due to the presence of the electron-donating group, depending upon its electron-donating ability. The activity order is as follows benzene toluene < p-xylene < anisole. 

Figure 4.2 Hammett relationship (log 11/2 versus a) in the benzoylation reaction of benzene and substituted aromatic compounds with benzoyl chloride over H-BEA zeolite modified by indium oxides...

Barthel, N., Finiels, A., Moreau, C., Jacquot, R., Spagnol, M. Kinetic study and reaction mechanism of the hydroxyalkylation of aromatic compounds over H-BEA zeolites, J. Mol. Catal., A, 2001, 169, 163-169. 

Casagrande, M., Storaro, L., Lenarda, M., and Ganzerla, R. 2000. Highly selective Friedel-Grafts acylation of 2-methoxynaphthlene catalyzed by H-Bea zeolite. Appl. Catal. A Gen. 201 263-270. 

Dispersion of Pt, as well as its combinations with Pd or Ir, in H-MOR and H-BEA zeolites were determined by H2 chemisorption using a pulse technique similar to that of Freel . The calcined catalysts were heated in the chemisorption furnace at 500°C for 3h in a H2 flow of 50 cc/min then in a N2 flow of 30 cc/min for 2 h (degassing). The furnace was shut off and the catalyst was cooled to room temperature. H2 was then pulsed into the N2 carrier until saturation (appearance of H2 peaks equivalent to non-chemisorbed pulses). The H2 uptake was calculated as hydrogen atoms adsorbed per total metal atoms on the basis of 1 1 stoichiometry... 

Table 1 Ammonia desorption enthalpy (Mid) cind peak temperature for catalysts containing 0.0-0.55wt%Pt supported on H-MOR and H-BEA zeolites...

In the past decade, Pt/H-MOR was considered as the begiiming of a new family of catalysts for the hydroisomerization of C5/C6 n-paraffms. More recently, Pt/H-BEA has been used. In this study, catalysts containing H-MOR and H-BEA zeolites loaded with 0.35-0.55 wt% Pt as well as 0.05-0.25 wt% Pd or Ir combined with 0.35 wt% Pt are tested for n-hexane hydroconversion. It is known that commercial hydroisomerisation and catalytic reforming catalysts normally contain 0.35-0.40 wt%Pt. 

Effect of Pt and PtPd or Ptir on their Dispersion in H-MOR and H-BEA Zeolites... 

Carbonylation of formaldehyde with carbon monoxide was also performed on various protonated zeolites such as H-ZSM-5, silicalite, H-MOR, H-Y, H-BEA, and MCM-41 (63). l,3-Dioxolan-4-one (l,3-DOX-4) is produced on Br0nsted acid sites of zeolite. H-ZSM-5, H-Y, and H-BEA zeolites with the three-dimensional channel system show the high activity for the formation of l,3-DOX-4. The reaction is carried out under batch conditions in dry methylene chloride solution, and trioxane is used as the formaldehyde source, at 40-180°C, 150-570 atm CO... 

Figure 2 Hydrogen evolution from aqueous NH3BH3 solution in the presence of hollow silica-alumina composite spheres prepared with (a) L(-l-)-arginine and (b) ammonia, (c) H-BEA zeolite, and (d) spherical silica-alumina composite particles.

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