Beta 811 zeolite

The cinnamyl ester can be prepared from an activated carboxylic acid derivative and cinnamyl alcohol or by transesterification with cinnamyl alcohol in the presence of the H-Beta Zeolite (toluene, reflux, 8 h, 59-96% yield). It is cleaved under nearly neutral conditions [Hg(OAc)2, MeOH, 23°, 2-A h KSCN, H2O, 23°, 12-16 h, 90% yield]or by treatment with Sulfated-Sn02, toluene, anisole, reflux. The latter conditions also cleave crotyl and prenyl esters. 

The preparation was performed on a commercial microcrystalline beta zeolite. The zeolite was treated with the Fenton s reagent and less than 0.3 wt% of carbon remained after the treatment. The porosity was fully developed as revealed by the pore-size distribution. Elemental analysis combined with TPR did confirm the high degree of Fe-exchange (98%) on the Bronsted sites. 

MicrocrystalUne zeolites such as beta zeolite suffer from calcination. The crystallinity is decreased and the framework can be notably dealuminated by the steam generated [175]. Potential Br0nsted catalytic sites are lost and heteroatoms migrate to extra-framework positions, leading to a decrease in catalytic performance. Nanocrystals and ultrafine zeolite particles display aggregation issues, difficulties in regeneration, and low thermal and hydrothermal stabilities. Therefore, calcination is sometimes not the optimal protocol to activate such systems. Application of zeolites for coatings, patterned thin-films, and membranes usually is associated with defects and cracks upon template removal. 

It must be noted that sometimes calcination is beneficial to create active species. Notable examples are the Sn-beta speciation [176] and generation of extra-framework Al-Lewis sites in beta zeolite for organic transformations... 

The first case study. Beta zeolite is the basis for many industrial applications... 

Figure 6.4 Features of beta zeolite after Fenton treatment, (a) Saito-Foley adsorption pore-size distribution from Ar-physisorption for (O) parent zeolite containing the template (no porosity) ( ) Fenton-detemplated and (V) commercial NH4-form BEA.

Fischer and Holderich (1999) have shown that Bayer-Villiger reaction of cyclopentanone with aqueous 30 % H2O2, to give delta-valerolactone, is amenable to catalysis with cationic ion-exchange resin (CIER), Amberlyst-I5 without cataly.sts the conversion and the yield of the product are poor. Nafion on silica also works but was found to be poor compared to Amberlyst-15. Beta zeolite also works but was found to be inferior to Amberlyst-I5. 

Another possibility for the plasma device is the generation of N02 for the enhancement of NH3-SCR at low temperature, (the so-called fast SCR reaction) which occurs if there is a 1 1 N0 N02 stoichiometry over V-Ti02 type catalysts and with variable stoichiometry over Fe-beta zeolite. Being able to switch on and tune N02 production over a limited temperature range will help to avoid N02 slip issues, that can be an issue for oxidation catalysts. Also, if tuned correctly, plasma can do the NO oxidation without in turn doing S02 oxidation and so generate N02 without making sulphates (and associated particulates). 

The NH4-Y (CBV712, ao = 24.35 A), H-Beta (CP811E-75), NH4-Beta (CP814E) zeolites were obtained from Zeolyst International. The NH4-Y and Beta zeolites were transformed to proton forms through step calcination procedure in a muffle oven. Zeolites containing 1 wt-% platinum were prepared by wet-impregnation method using hexachloroplatinic acid as the Pt-source. 

Furthermore, while no significant difference in the product distribution, with the exception of the trans-decalin/cis-decalin ratio, is observed for the tested proton-form zeolites, dissimilarity between Pt/H-Y on one hand and both Pt/H-Beta zeolites on the other hand is found (Figure 6). More ROP and CP, accompanied by less Iso, are formed on Pt/H-Y than on Pt/H-Beta zeolites. This implies that the consecutive ring opening and cracking are faster over Y-zeolite than over Beta-zeolites resulting in lower concentration of isomers and higher concentrations of ROP and CP. 

Figure 7 A) Dependence ofROP concentration on the concentration of Tso, B) Dependence of OP concentration on the concentration of ROP. TT-zeolites (filled), Pt-zeolites (open) Beta-zeolites ( , U), Y-zeolite ( , O).

Keywords montmorillonite Beta zeolite nano zeolite. 

Selectivity to p-isopropyl toluene being close to 30 % was achieved with SSZ-33, SSZ-35 and Beta zeolites. This is connected with the 12-MR channels in SSZ-33 and Beta. In the case of SSZ-35 the presence of 18-MR cavities decreased the differences in the rate of transport of individual isopropyl toluene isomers. In contrast, ZSM-5 zeolite behaves as para-selective catalyst in this alkylation reaction, the selectivity to p-isopropyl toluene reached 76 % after 180 min of T-O-S. 

The highly oxygenated bio oil can be de-oxygenated, and thereby upgraded, over acidic zeolite catalysts through the formation of mainly water at low temperatures and C02 and CO at higher temperatures [1-3], Successful catalytic pyrolysis of woody biomass over Beta zeolites has been performed in a fluidized bed reactor in [4]. A drawback in the use of pure zeolitic materials has been the mechanical strength of the pelletized zeolite particles in the fluidized bed. 

Zeolite-bentonite hybrid catalysts have been prepared from ZSM-5 and Beta zeolites supplied by Zeolyst International and bentonite. The zeolite to bentonite ratio was 35/65. The Si02 to A1203 ratio of ZSM-5 and Beta was 23 and 25, respectively. The preparation of the material was conducted in the following way. The zeolite and the bentonite were bound together through mixing in a 6 1 aqueous solution at 60°C for 2h,... 

Crystallinity of the final zeolites was high as determined by XRD measurements (diffraction patterns not shown) and was confirmed by their high micropore volumes, which are compared in table 1 together with other physico-chemical properties. A commercial beta zeolite (CP811, Zeolyts Int.) is included for comparison purposes. 

Tablel. Physico-chemical properties of ITQ-21 and BETA zeolites.

Figure 3-a shows the propylene conversion obtained on ITQ-21 and beta zeolites at space velocity of 18 h"1 and different temperatures. It can be seen that both zeolites, ITQ-21 and BETA, are initially highly active, but whereas ITQ-21 maintains full propylene conversion along the 8 hours of reaction at 125°C, zeolite BETA is completely deactivated at TOS=100 min. Increasing contact time (WHSV=12 h 1) results in a slight improvement for BETA (Figure 3-b), as conversion at 50 min TOS is in this case above 90%, but results are still far from those obtained with ITQ-21. 

ITQ-21 presents excellent catalytic properties for the production of cumene, being more active and stable towards deactivation and presenting lower selectivity to NPB than a comparable beta zeolite. The benefits of ITQ-21 can be directly related to its open three-dimensional crystalline structure that favors diffusion of the products and minimizes undesired consecutive reactions. 

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

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. 

Keywords Friedel-Crafts acylation, Beta zeolite, hierarchical zeolites. 

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. 

The catalytic activity of hierarchical and conventional Beta zeolites for acylation of 2-MN is displayed in Figure 2(a) The Beta (PHAPTMS) sample shows a superior catalytic activity than the conventional one, due to its enhanced textural properties. In this case, the bulky nature of both substrate and products may cause the existence of diffusional problems inside the zeolitic channels, which are attenuated in the modified Beta sample due to the presence of the hierarchical porosity. Regarding the product distribution (Figure 2(b)), two main products are observed and a third isomer, 8-A,2-MN isomer is produced just in minor amounts. Interestingly, the selectivity towards the desired isomer increases in the material obtained from silanized seeds, reaching values around 75%. Probably, the active sites located on the surface of the secondary porosity are able to catalyze also the formation of 6-A,2-MN by transacylation. However, this reaction is expected to be strongly hindered in the conventional Beta zeolite since it requires the participation of two bulky molecules as reactants. 

Radioactive 11C-methyl labeling for study of methanol co-reaction with methyl iodide on Fe -Beta zeolite... 

The wide-pore H-Beta zeolite has strong Bronstcd acid hydroxyl groups and other advantage chemical environment which govern the adsorption and consecutive conversion of methanol to dimethyl ether and further to hydrocarbons, mostly isobutane. This character can be modified by Fe ion-exchange. 

In this work the methanol and methyl iodide conversion and their co-reaction are investigated on Fe-Beta zeolite without any oxygen. Partly Fe-ion-exchanged Beta-300 i.e. Fe-H-Beta-300 (shortly Fe-Beta-300) zeolite keeps the light acidity to a certain extent, however the presence of Fe ions (as transition metal, Fe is an excellent Lewis acid) can modify the reaction pathway. This Fe-Beta-300 has been tested already by low temperature peat pyrolysis [6], At present, the adsorption as well as desorption of methanol are followed-up by radiodetectors using ( -radioisotopic labeling [4, 7]. The... 

In further work, the same research group showed that it was possible to effect transacetalation of the initial butyl glucosides 2, 3 with octanol and dodecanol over H-beta zeolites. Direct Fischer glucosylation, leading to the desired long-chain glucosides 4, 5, was also possible (Scheme l).37... 

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