Zeolite catalysts for

Jacobs et al. employed an acidic zeolite catalyst for the racemization of sec-alcohols, which occurs through the formation of carbocations [44] (Figure 4.19). The KR is catalyzed by CALB in the presence of vinyl octanoate as acyl donor. DKR takes place successfully in a biphasic system (octane/H2O, 1 1) at 60 °C. 

Many of these problems disappeared in 1983 when Taramasso, Perego, and Notari synthesized titanium silicalite-1 (TS-1),1 which greatly affected the use of zeolite catalysts for practical oxidation chemistry. This catalyst shows outstanding activity, selectivity, and stability below 100°C. 

Products Company and Davison (W.R. Grace) Catalysts) and Hydrocarbon Technologies, Inc. ART provides non-zeolitic catalysts for ebullating residue hydrocracking and fixed bed pretreating HDT [140], A nanoscale iron based, slurry catalyst is recommended for coal liquefaction, while a molecule-sized and chemically in situ generated catalyst is employed for the high conversion of asphaltenic fractions or heavy oils [141],... 

IsoPlus Not a process but a range of zeolite catalysts for making iso-olefins by FCC. Developed by Englehard. 

An increased selectivity for phenol in the oxidation of benzene by H202 with TS-1 catalyst in sulfolane solvent was attributed to the formation of a bulky sulfolane-phenol adduct which cannot enter the pores of TS-1. Further oxidation of phenol to give quinones, tar, etc. is thus avoided. Removal of Ti ions from the surface regions of TS-1 crystals by treatment with NH4HF2 and H202 was also found to improve the activity and selectivity (227). The beneficial effects of removal of surface Al ions on the catalytic performance of zeolite catalysts for acid-catalyzed reactions have been known for a long time. 

The activity of zeolite catalyst for the cracking of cumene was measured at several onstream periods at cumene flow rates of u = 0.01 mol/s and 0.32 mol/s (IECPDD 22 609, 1983). The results are tabulated. Taking the relation to be... 

Early attempts to utilize the high acid activity of faujasite zeolite catalysts for direct xylene isomerization suffered from low selectivity. Considerable improvement was obtained first by using a large pore zeolite (7) catalyst and subsequently in several process modifications that use ZSM-5 as catalyst (2). In the following we will show how these selectivity differences can be related to structural differences of the various zeolites. 

P., and Romano, U. (2003) A priori selection of shape-selective zeolite catalysts for the synthesis of 2,6-dimethylnaphthalene. J. Catal., 217, 298-309. 

I 70 Advanced Design of Catalyst Surfaces with Metal Complexes for Selective Catalysis Table 10.6 Performances of Re/zeolite catalysts for direct phenol synthesis at 553 K". 

Zeolite catalysts in many forms are used for important commercial processes. The studies were extended to L zeolites, mordenite, erionite, and dealuminated faujasites and mordenites. More attention is paid now to zeolites with univalent and multivalent cations and to multicomponent catalysts. Among these some important examples are the tellurium-containing catalyst for hydrocarbon dehydrocyclization (42), the difunctional Ni- and Pd-zeolite catalysts for benzene hydrodimerization to phenylcyclohexane (42), the catalyst for the hydrogenation of phenol cyclohexanol (44), the 4% Ni/NaY which forms butanol, 2-ethylhexanol, 2-ethylhexanal, and 2-ethylhexanol from a mixture of n-butyraldehyde and hydrogen. 

To improve process economics, further work is needed to improve catalyst lifetimes. A more stable system employed a noble metal-loaded potassium L-zeolite catalyst for the condensation of ethanol with methanol to produce a 1-propanol and 2-methyl-l-propanol (US patent no. 5,300,695) (18). However, yields were small compared with the large amounts of CO and C02 produced from the methanol. More recently, Exxon patented a noble metal-loaded alkali metal-doped mixed metal (Zr, Mn, Zn) oxide (US patent nos. 6,034,141 and 5,811,602) (19,20). The catalyst was used in a syngas atmosphere. As with other catalysts, the higher temperatures resulted in decomposition of methanol. Changes in catalyst composition were noted at higher temperatures, but the stability of the catalyst was not discussed. Recently, compositions including Ni, Rh, Ru, and Cu were investigated (21,22). 

Therefore the association in the same team of experts in organic chemistry and in catalysis on zeolites is ideal to develop zeolite catalysts for Fine Chemicals synthesis. The organic chemists bring the necessary knowledge about reaction mechanisms (with therefore the possible prediction of secondary products, etc.) and advanced methods in organic analysis and product purification the specialists in catalysis on zeolites orient the choice of the zeolite catalysts and of activation procedures as well as the selection of the reactor and operating conditions. Moreover, the researchers should have a two-fold culture with, in addition to a... 

Duncan, C. B. Process and surface-deactivated ZSM-23 zeolite catalysts for a C2-6 olefin oligomerization process. WO 2003082781, 2003. 

The transport and adsorption properties of hydrocarbons on microporous zeolites have been of practical interest due to the important properties of zeolites as shape-selective adsorbents and catalysts. The system of benzene adsorbed on synthetic faujasite-type zeolites has been thoroughly studied because benzene is an ideal probe molecule and the related role of aromatics in zeolitic catalysts for alkylation and cracking reactions. For instance, its mobility and thermodynamic properties have been studied by conventional diffusion 1-6) and adsorption 7-9) techniques. Moreover, the adsorbate-zeolite interactions and related motion and location of the adsorbate molecules within the zeolite cavities have been investigated by theoretical calculations 10-15) and by various spectroscopic methods such as UV (16, 17), IR 17-23), neutron 24-27), Raman 28), and NMR 29-39). 

Thus, based on the data presented above, we can conclude that further improvement of the Ga-containing zeolite catalysts for direct DHI of n-butane into isobutene requires supression of the catalyst aromatisation activity. Further reduction of the cracking activity of the catalysts is also necessary. 

To obtain the coking mechanism of zeolite catalyst for SCFP alkylation of benzene, two kinds of the zeolite used in LP and SCFP alkylation processes were analyzed by using the conventional catalyst analysis methods. Fresh zeolite is also analyzed for comparison. 

The use of bifunctional metal/zeolite catalysts for the conversion of synthesis gas (carbon monoxide and hydrogen) to gasoline range hydrocarbons has recently attracted much attention. For example, the combination of metal oxides with the medium pore ( 6A) zeolite ZSM-5 and the use of a metal nitrate impregnated ZSM-5 catalyst have been shown to produce gasoline range hydrocar-... 

Table 3 Water tolerance of Fe-exchanged zeolite catalysts for the selective reduction of NOx by HCs... 

Figure 10 Water tolerance of mordenite type zeolite catalysts for the reduction of NO by...

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