Dehydrogenation heterogeneous catalytic

As a synthetic tool, heterogeneous catalytic dehydrogenations offer selective conversions of functional groups. Most popular dehydrogenations involve... 

In general, a catalytic reaction may be named by adding the adjective catalytic to the standard chemical term for the reaction, for example, catalytic hydrogenation (or, if clarity demands, heterogeneous catalytic hydrogenation), catalytic hydrodesulphurisation, catalytic oxidative dehydrogenation, catalytic stereospecific polymerisation. 

Interestingly, the by-product in the above-described hydrocyanation of butadiene, 2-methylglutaronitrile, forms the raw material for the Lonza process for nicotinamide (see earlier) [123]. Four heterogeneous catalytic steps (hydrogenation, cyclisation, dehydrogenation and ammoxidation) are followed by an enzymatic hydration of a nitrile to an amide (Fig. 1.50). 

Based on the above considerations, the types of reactions that are amenable to inorganic membrane reactors in the first wave of industrial implementation will probably be as follows (1) The reactions are heterogeneous catalytic reactions, particularly dehydrogenation processes (2) The reaction temperature exceeds approximately 200°C (3) When the reactions call for high-purity reactant(s) or produces) and the volume demand is relatively small, dense membrane reactors (e.g., Pd-based) can be used. On the other hand, if high productivity is critical for the process involved, porous membrane reactors are necessary to make the process economically viable. 

A heterogeneous catalytic process involves more than one phase usually the catalyst is a soHd and the reactants and products are in liquid or gaseous form. Much of the benzene produced in this country today is manufactured from the dehydrogenation of cyclohexane (obtained from the distillation of crude petroleum) using platinum-on-alumina as the catalyst ... 

C2H-OH Vapor phase catalytic dehydrogenation Heterogeneous Ethanol is passed over Cr-activated Cu catalyst at 260° 290°C. and atmospheric pressure... 

Although a disciple of Zelinsky, Balandin succeeded in influencing the work of Zelinsky s school almost immediately by studying the kinetics of heterogeneous catalytical reactions in a flow system. His postgraduate thesis Kinetics of the Catalytic Dehydrogenation of Cyclo-hexanol and Cyclohexanone was finished in 1928, and the following... 

The modern beginning of the heterogeneous catalytic oxidation of olefins to aldehydes may be taken as the discovery of the oxidation of propylene to acrolein over cuprous oxide by Hearne and Adams (5 ). This reaction has been carried to commercial operation by Shell Chemical Company. More recently, the use of bismuth phosphomolybdate has been demonstrated for the oxidation of propylene to acrolein by Veatch and co-workers (88), and, in the presence of ammonia, to acrylonitrile by Idol (89). It was also shown, by Heame and Furman (90), that diolefins could be made from C4 and higher olefins by oxidative dehydrogenation over a bismuth molybdate catalyst. From these beginnings, information on olefin oxidation has increased very rapidly, both in journal and patent literature. We shall make no attempt to review the large number of patents that have issued, but shall limit ourselves mainly to journal literature. 

Heterogeneous catalytic hydrogenation and dehydrogenation reactions proceed in a pathway of elementary steps that involve mass transfer of reactant molecules to the catalyst surface, adsorption and migration of reactant molecules on the catalyst surface to active sites, reaction conversion to the product on catalyst surface and then desorption of product molecules from the catalyst surface. Microreactors in their various geometries have the potential for detailed studies of reactions for multiple... 

In heterogeneous metal catalysis alkanes, alkenes, and aromatics adsorbed on the metal surface rapidly exchange hydrogen and deuterium. The multiple adsorption of reactants and intermediates lowers the barriers for such exchange processes. Hydrogenation of unsaturated aliphatics and isomerisation can be accomplished under mild conditions. Catalytic dehydrogenation of alkanes to alkenes requires temperatures >200 °C, but this is because of the thermodynamics of this reaction. 

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