Catalytic reactions involving hydrogenation

In several papers dealing with catalytic reactions involving hydrogen and unsaturated hydrocarbons the observed self-poisoning of nickel or its alloys has been quite properly attributed to the presence of carbonaceous... 

The fact that only a low amount of metal deposit is required to render catalytic reactions involving hydrogen over illuminated Ti02 is advantageous to limit back reactions catalyzed by the metal, as well as for economical reasons. Conversely, this result illustrates the limitations encountered when trying to modify the surface of a semiconductor. 

A considerable proportion of the investigations of catalytic reactions involve hydrogen or hydrogen-containing compounds. In all of the cases studied, intermolecular transfer of H atoms takes place and the evidence points to an intermediate chemisorption of H atoms (or ions) on the catalyst surface. 

Yatsimirskii (1%4) studied many catalytic reactions involving hydrogen peroxide in acid media. One of those reactions was the oxidation of potassium iodide by hydrogen peroxide in the presence of a catalyst according to the equation... 

Yatsimirskii, K. B. (1964). The use of catalytic reactions involving hydrogen peroxide in the study of the formation of complexes and in the development of very sensitive analytical methods. In Catalysis and Chemical Kinetics, ed. A. A. Balandin et al., pp. 201-6. New York Academic Press. 

Experience in air separation plant operations and other ciyogenic processing plants has shown that local freeze-out of impurities such as carbon dioxide can occur at concentrations well below the solubihty limit. For this reason, the carbon dioxide content of the feed gas sub-jec t to the minimum operating temperature is usually kept below 50 ppm. The amine process and the molecular sieve adsorption process are the most widely used methods for carbon dioxide removal. The amine process involves adsorption of the impurity by a lean aqueous organic amine solution. With sufficient amine recirculation rate, the carbon dioxide in the treated gas can be reduced to less than 25 ppm. Oxygen is removed by a catalytic reaction with hydrogen to form water. 

The scope of reactions involving hydrogen peroxide and PTC is large, and some idea of the versatility can be found from Table 4.2. A relatively new combined oxidation/phase transfer catalyst for alkene epoxidation is based on MeRe03 in conjunction with 4-substituted pyridines (e.g. 4-methoxy pyridine), the resulting complex accomplishing both catalytic roles. 

Until now examples for catalytic reactions involving ferrates with iron in the oxidation state of -l-3 are very rare. One example is the hexacyanoferrate 8-catalyzed oxidation of trimethoxybenzenes 7 to dimethoxy-p-benzoquinones 9/10 by means of hydrogen peroxide which was published by Matsumoto and Kobayashi in 1985 [2]. Using hexacyanoferrate 8 product 9 was favored while other catalysts like Fe(acac)3 or Fe2(S04)3 favored product 10 (Scheme 2). The oxidation is supposed to proceed via the corresponding phenols which are formed by the attack of OH radicals generated in the Fe/H202 system. 

The material balance was calculated for EtPy, ethyl lactates (EtLa) and CD by solving the set of differential equation derived form the reaction scheme Adam s method was used for the solution of the set of differential equations. The rate constants for the hydrogenation reactions are of pseudo first order. Their value depends on the intrinsic rate constant of the catalytic reaction, the hydrogen pressure, and the adsorption equilibrium constants of all components involved in the hydrogenation. It was assumed that the hydrogen pressure is constant during... 

The overall catalytic reactions involved in the two step synthesis of hydroxymethyl ated PBD are given by Equations 1-6. It can be seen from reactions (1-6) that the addition of -CHO functional group can occur in three ways resulting in the formation of three types of hydroformyl ated PBD repeating units as shown by species A, B or C. Subsequent hydrogenation of units A, B and C result in the formation of hydroxymethylated PBD repeating units A, ... 

Catalytic reactions involving addition of two molecules of butadiene and hydrogen transfer from an acidic carbon atom (adjacent to a ir-allyl group) to the nickel oxygen bond were recently described (example 12, Table IV). 

Thus, the Pd layer serves multiple purposes its surface catalyzes the dissociation of molecular hydrogen, it selectively forms palladium hydride, and it can be used as the metal gate of the field-effect devices. The scheme in Fig. 6.34 also shows the catalytic reaction involving oxygen. If both oxygen and hydrogen are present, the steady-state response of the Pd IGFET includes the surface-catalyzed oxidation. 

Bifunctional catalytic reactions involve a series of catalytic steps over acidic and hydrogenating-dehydrogenating sites with formation of intermediate compounds. Thus n-hexane (hydro)isomerization involves successively n-hexane dehydrogenation in n-hexenes (metal catalyzed), skeletal isomerization of n-hexenes into isohexenes over protonic acid sites followed by the (metal catalyzed) hydrogenation of isohexenes into isohexanes (Figure 1.4). 

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