Gallium-containing catalysts

In the case of 38, a significant amoimt of olefin was foimd to isomerize. This observation implies that the isomerization and hydroformylation reactions take place simultaneously. The former process results in the formation of internal olefins which are ultimately converted into aldehydes in the case of 36 and 37. However, the hydroformylation process of the internal olefins is apparently less effective with the indium-containing catalyst 38. This property allows the isolation of substantial yields of internal olefins in catalytic reactions (17-37% after 18 h). It can be explained by a simple reaction scheme involving the individual rate constants of the various processes, as shown in Scheme 18. It appears from the data presented in Table 7 that the rate constants 2 and are larger than fci in the case of the aluminum- and gallium-containing catalysts 36 and 37, whereas the reverse is true for indium-containing 38. 

To gain a better understanding of the observed parameters listed in Table 7, additional experiments were performed. The formation of these internal olefins in the case of the aluminum-containing catalyst 36 was low and remained more or less constant over time. In the case of 37, the isomerization selectivity increased with time up to 2 h, indicating the importance of the isomerization. However, the ability of the gallium-containing catalyst 37 to catalyze hydroformylation of the internal olefins decreased the concentration of internal olefins present in the solution. In the case of the indium-containing catalyst 38, the rates of formation of both aldehydes and internal olefins increased as a function of time, and the process was not complete even after 5 h. 

Fig. 4 - NO, NO2 concentrations and N2 production as functions of reaction temperature for gallium-containing catalysts.

Aromatization activity of gallium containing MEl and TON zeolite catalysts in n-butane conversion effects of gallium and reaction conditions. Appl. Catal. A, 316, 61-67. 

In order to get better understanding of the role of gallium and acid sites in n-butane transformation over Ga-containing catalysts, we have considered the rate data obtained over H- and Ga-theta-1 catalysts. These catalysts were chosen, since they produced much better results when compared with the ferrierite-based catalysts. Consequently, the activities of the theta-1 catalysts in the initial n-butane dehydrogenation and cracking steps were determined. This was done by the extrapolation of the rate data on formation of the primary reaction products (hydrogen, methane and ethane) to zero n-butane conversions, as shown in Figure 3. 

Xe of adsorbed xenon 602 Pt of supported catalyst 604 ° T1 of thallium-containing Be of beryllium-substituted V of vanadium-containing catalysts 649 Ga of gallium-containing 656 La of lanthanum-substituted 677... 

Raichle, A. Moser, S. Traa, Y. Hunger, M. and Weitkamp, J., Gallium-containing zeolites as valuable catalysts for the conversion of cycloalkanes into a premium synthetic steam-cracker feedstock, Catalysis Communications 2(1), 23-29 (2001). 

Apart from the aluminum-containing catalyst, the same group also reported a gallium-sodium-binaphthol complex ((/J)-GaSB) and applied them in the Michael reaction of dibenzyl malonate with cyclohexenone (Table 9.3). In the presence of (/ )-GaSB, up to 98% ee was obtained, whereas the yield dropped to 45% even after a prolonged reaction time. Interestingly, when sodium malonate was added to the reaction system as the additive, 2-cyclohexen-l-one could be transformed completely into 1,4-adduct with 96% ee. 

A completely new approach for BTX production has emerged in recent years. It converts to paraffins into aromatics using a modified ZSM-5 zeoHte catalyst which contains gallium (19). An example of this approach, the Cyclar process, has been in commercial operation by British Petroleum at Grangemouth, Scotiand since August 1990 (20). It uses C —feed and employs UOP s CCR technology to compensate for rapid catalyst coking. 

F. J. Luczak, D. A. Landsman (Pt-Ga-Co/Cr) USP 4,806,515, Ternary Fuel Cell Catalyst Containing Platinum and Gallium, File date 16 Nov 1987, Issue date 21 Feb 1989. 

There is considerable interest in isomorphous substitution of aluminium in the zeolite framework by other elements and some papers have described the synthesis of MFI zeolites containing boron, gallium, titanium and iron as lattice elements (ref.1-3). The replacement of Al ions with the ions of another element can modify both the acidity and pore size features of the zeolite (ref.4, 5), resulting in modification of the catalytic property of zeolite catalysts (ref.6-8). 

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