Zeolite M

Suntornpun, R. (2002) Acid-base interaction between Cs aromatics and X and Y zeolites. M.S. Thesis in Petrochemical Technology. The Petroleum and Petrochemical College, Chulalong-kom University, Bangkok, Thailand. 

Mumpton, F.A., Mineralogy and Geology of Natural Zeolites, M.S.A. Short Course Notes, Southern Printing Company (1977). 

Details of the numerical procedure will be published elsewhere [10]. The sample geometry (e.g. spherical or cylindrical symmetry) is taken into account. The parameters adjusted in fitting the experimental data are (a) the transport difiSisivity, D, and (b) the rate controlling mass transfer from the surrounding gas phase into the zeolite, m. The crystal size has been determined from SEM micrographs and is thus fixed. 

A Review of Ab Initio Calculations on Proton Transfer in Zeolites (M. Allavena D. White)... 

Zeolite M (M-Si-ZSM-5) Nucleation rate constant kf Crystal growth-rate constant K Gel-dissolving rate constant k4 Si02/M20 (mol/mol)... 

REACTIONS OF METHANOL AND TOLUENE OVER MOLYBDENUM ZEOLITES M.M. HUANG1 and R.F. HOWE2... 

Aerobic epoxidation of different alkenes, including a number of natural terpenes, efficiently occurs under mild reaction conditions in the presence of isobutyraldehyde as a reductant and MNaY and MNaZSM-5 type zeolites (M=Co(II), Cu(II), Ni(II) and Fe(III)) as catalysts. Yields of the epoxidation products vary from 80 up to 99% depending on the olefin and catalyst. The reaction proceeds via chain radical mechanism, acylperoxy radicals being the main epoxidizing species. 

Three-dimensional structures Zeolites M + (AhSl2-x02)-nH20 AlP04-n, SAPO-n... 

P-25 - Development of a tight-binding treatment for zeolites M Elstner, A. Goursot, Z. Hajnal, T. Heine and J. Weber... 

Simulating shape selectivity in alkane hydroconversion by zeolites M Schenk, T.L.M. Maesen andB. Smit... 

P-24 - Hexenes obtaining on the nickel - ion exchanged zeolites M.K. Munshieva... 

Figure 1 shows that there is a very rapid deactivation of the USHY zeolite m-xylene conversion passes from 55% at 2 minutes to 3% at 75 minutes. This deactivation can be related to the retention of carbonaceous compounds on the zeolite ( coke ). The coke content of the zeolite first increases very rapidly with time-on-stream then more slowly. 

However, another type of reactions of benzene derivatives was studied by in-situ IR spectroscopy as well, viz. the side-chain alkylation of alkylbenzenes, for instance of toluene, over basic zeolite catalysts such as M -X zeolites (M=Na, K, Rb, Cs) [901,902]. The intermediate conversion of methanol to formaldehyde turned out to be crucial for the side-chain alkylation as well as a strong polarization of the methyl group of toluene, the preferential adsorption of toluene, and a sufficient basicity, i.e., base strength of the catalyst. Related to these IR studies of side-chain alkylation of toluene were in-situ IR spectroscopic investigations of the decomposition of methanol over basic zeolites (M+-X, M =Na+, K+, Rb, Cs+ Na-ZSM-5 and Cs-ZSM-5 [903]). It was shown that over weakly basic zeolites (Na-ZSM-5, Cs-ZSM-5) dimethyl ether was formed from methanol, whereas over more strongly basic X-type zeolites formaldehyde was produced, which is an indispensable intermediate for the side-chain reaction (vide supra). 

As another example, the protonated forms of zeolites M, omega, L, Y, beta, ZSM-5 and SAPO-5 have served as media for the alignment and packaging of incarcerated methylacetylene in order to explore the concepts for the production of tailored polymers with possible useful nonlinear optical properties [137]. 

The acid forms of aluminosilicate zeolites have found wider use as acid catalysts than any other materials. Their outstanding utility derives from their relatively high acid strength, their high hydrothermal stability, their ability to impart shape selectivity to product distributions and the reproducibility with which they can be synthesised and modified. Each of these advantages stems directly from their crystalline structure. The two basic types of acid site types in microporous solids are Bronsted, which are protons located at bridging sites (Si-O-Al in zeolites, M-O-P in aluminophosphates) and Lewis, usually incompletely coordinated metal cations (especially aluminium in zeolites) in... 

The tin zeolites M-Sn-MOR and T-Sn-MOR were studied by " Sn NGR method [94H1] - Table 9. For samples, e.g., M-Sn-MOR, prepared by microwave-assisted hydrolysis of oi notin chloride (Chap. 8.1.6.8.1 in this volume), the " Sn NGR spectra depicted a single peak close to zero velocity. These spectra were attributed to the presence of tin exclusively in finely dispersed Sn02- For T-Sn-MOR samples, prepared from Na-MOR and either Sn -chloride or Sn -sulfate, the spectra arise exclusively from Sn in dispersed oxide. In case of T-Sn-MOR prepared from H-mordenite and Sn -cloride, an additional doublet appeared. This has been attributed to residual Sn species present as impurity. 

Using different catalysts in N2O decomposition (M-zeolites - M-Cu, Co, Fe, etc.) of perovskite-like mixed oxides and supported precious metal (Pd, Rh, etc.), it was concluded that ... 

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