Acid-base testing of catalysts using 1-butene isomerization as test reaction

Catalysts tested were classified into two groups according to the initial ratio ofcis- andtrans-2-butene in the products. CaY, Fe-PILC and Al-PILC proved to be acidic while LiY, NaN₃/NaY and calcined hydrotalcite (HT) basic materials.     

Diffusion of sodium from the exterior to the interior surface of faujasite zeolites exchanged for different alkaline metal ions

Metallic sodium formed upon thermal decomposition of NaN₃ migrates from the external surface of zeolite into its pore system. Interaction takes place between neutral sodium and ionic cesium, too, as proved by ESR spectroscopy.     

Transformation of Chlorofluorocarbons on Zeolites: Dealumination

Dealumination of zeolites is regarded as a useful postsynthesis method for the modification of Si/Al ratio. Among other compounds phosgene proved to be an excellent reactant for aluminium removal from zeolite frameworks. The interaction of zeolites with chlorofluorocarbons also leads to dealumination, resulting in the formation of a phosgene intermediate that has been proven by IR and NMR spectroscopy.     

Hydrodechlorination of chlorophenols over Pt- and Co-containing ZSM-5 zeolite catalysts

Summary Some of the chlorinated organic compounds are widely used commercially because of their advantageous chemical/physical properties or being toxic to pestiferous living substances. We have prepared and applied monometallic Co-, Pt- and bimetallic Co,Pt-ZSM-5 zeolite catalysts for hydrotreating 2- and 4-chlorophenols in the temperature range of 300-400 oC using a fixed-bed laboratory reactor system equipped with a gas chromatograph for analysis. In the reaction over the Pt-containing catalyst high initial conversion can be observed, the compounds transform to cyclohexanone, however, the activity of the catalyst decreases even during the 2 h reaction time. In the presence of Co-ZSM-5, the main reaction is simple hydrodechlorination resulting in phenol as the main product, and this catalyst is stable, and the activity does not change. The bimetallic catalyst combines the advantages (and disadvantages) of the monometallic samples. The hydroconversion of chlorophenols resulted in the formation of cyclohexanone with high initial selectivity. However, because of the relatively short catalyst lifetime further optimization is necessary before practical application.</o:p>     

Characterization of cationic pillared layer clays

Na-montmorillonite and its Al-, Ti-, Fe-, Cr-, Zr- and Sn-pillared derivatives (pillared layer clays) were prepared and characterized by instrumental methods and a chemical reaction. Structural characterization involved X-ray fluorescence (XRF) analysis, X-ray diffractometry (XRD),²⁹Si and²⁷Al MAS NMR spectroscopies, thermogravimetric (TG) and BET measurements. By the distinctly characteristic shapes of the d₀₀₁ vs. temperature curves two groups could be distinguished, (i) Al-PILC, Ti-PILC, Cr-PILC, Zr-PILC and (ii) Fe-PILC, Sn-PILC, Na-montmorillonite. On montmorillonite isomerization of cyclopropane only occurred while oligomerization followed isomerization over Al-PILC. This latter reaction was attributed to Lewis and (the considerably smaller number of) Br?nsted acid sites whose number, strength and accessibility increased due to pillaring.     

Thermal behavior of alkali metal azides in NaY-FAU zeolite

The thermal behavior of pure alkali metal azides and their mechanical mixtures with NaY-FAU zeolite was investigated by means of thermogravimetry and IR spectroscopy. LiN₃, KN₃, RbN₃ and CsN₃ were prepared from NaN₃ by ion-exchange. The pure azides exhibited low thermal stability, hindering the precise spectroscopic characterization in some cases. The decomposition of each azide in the zeolite took place above the temperature characteristic for the pure azide, demonstrating the stabilization of the azide in the zeolite cavities. This feature was the only common characteristic established for the azide/zeolite systems.The financial support of the National Science Foundation of Hungary (OTKA 1604/91) is gratefully acknowledged.     

IR investigation of NH4Y zeolite samples poisoned with sodium vapor

The interaction between sodium atoms (obtained by thermal decomposition of NaN₃) and acidic OH groups of the zeolite framework has been investigated by IR spectroscopy. Reduction in band intensities could be observed, its extent depending on the amount of NaN₃ and temperature. Impregnated samples showed displacement of the N=NN IR band characteristic of salt occlusion.

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, NaN₃, OH . e, NaN₃ . N=NN^–, .

     

A novel method for the preparation of extensively dealuminated faujasites

Open structure faujasites may be dealuminated with retention of crystallinity using phosgene (or similar reactants) provided the sample has been made ultrastable in a previous procedure.

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Orientational Design of Anisotropic Materials Using the Hill and Tsai–Wu Strength Criteria

Linearly elastic two- and three-dimensional orthotropic materials are considered. The problems of optimal material orientation are studied in the cases of the Hill and Tsai–Wu strength criteria. The necessary optimality conditions are derived for a 3D orthotropic material. In the case of a 2D orthotropic material, an analytical solution is obtained. An analysis of global and local extrema is presented.     

IR spectroscopic study of the hydrodechlorination of 2-chlorophenol over nobel metal containing zeolites

Some of the chlorinated organic compounds are widely used commercially because of their advantageous chemical/physical properties or having toxicity for pestiferous living substances. Platinum and palladium supported on different carriers play very important role in catalytic hydrodechlorination of these compounds. We have prepared and applied Pt- and Pd-containing zeolite catalysts for hydrotreating of 2-chlorophenol using IR spectroscopic self-supporting wafer technique.