Dehydrogenative isomerization

Dehydrogenated isomeric adducts were also present. 

The reforming of EG can be accompanied by significant production of acetic acid through bifunctional dehydrogenation/isomerization and dehydration/hydrogena-tion routes over the metal and the support. 

These dehydrogenation/isomerization reactions are typically undesirable because the product acids are generally low in value, highly stable in aqueous solution and corrosive towards catalysts and equipment. 

The elements of range in value from 0 to 1 and are the ratio of the reformer kinetic constants at time on stream t to the values at start of cycle. At any time on stream t, the deactivation rate constant matrix K(a) is determined by modifying the start-of-cycle K with a. From the catalytic chemistry, it is known that each reaction class—dehydrogenation, isomerization, ring closure, and cracking—takes place on a different combination of metal and acid sites (see Section II). As the catalyst ages, the catalytic sites deactivate at... 

Paraffin dehydrogenation, isomerization, and dehydrocyclization Paraffin cracking and isomerization Alcohol -> olefin + H20 Paraffin hydrocracking Olefin polymerization,... 

So far, more than 70 different catalytic reactions (oxidations, hydrogenations, dehydrogenations, isomerizations, decompositions) have been electrochemically promoted on Pt, Pd, Rh, Ag, Au, Ni, IrC>2, Ru02 catalysts deposited on O2- (YSZ), Na+ (/i"-Al2Oi), H+ (Ca/,ro2)ln0. Oj a, Nafion), F (CaF2), aqueous, molten salt, and mixed ionic-electronic (TiC>2, CeC>2) conductors [23]. 

The objectives of the catalytic reforming of naphtha are to increase the naphtha octane number (petroleum refination) or to produce aromatic hydrocarbons (petrochemistry). Bifunctional catalysts that promote hydrocarbon dehydrogenation, isomerization, cracking and dehydrocyclization are used to accomplish such purposes. Together with these reactions, a carbon deposition which deactivates the catalyst takes place. This deactivation limits the industrial operation to a time which depends on the operational conditions. As this time may be very long, to study catalyst stability in laboratory, accelerated deactivation tests are required. The knowledge of the influence of operational conditions on coke deposition and on its nature, may help in the efforts to avoid its formation. 

Transformations of hydrocarbons promoted by solid metals and their oxides play very important roles in chemical industry [1], Heterogeneous metal-containing catalysts [2] are widely employed for cracking (see, e.g [3]) of oil fractions, oxidation, dehydrogenation, isomerization and many other processes of saturated as well as alkylaromatic hydrocarbons. 

Catalytic reactions can be classified into structure-insensitive (hydrogenation, dehydrogenation, isomerization, hydrogen exchange) or structure-sensitive (hydrogenolysis, CO/H2, NH3 synthesis) reactions depending on the extent to which the rate of the reaction and its selectivity are affected by the size and morphology of the metal particles. 

Metallic surface Chiral support Hydrogenation Dehydrogenation Isomerization... 

Plant cells in cultures can transform natural or artificial compounds through a variety of reactions, such as hydrogenation, dehydrogenation, isomerization, glyeosylation, and hydroxylation, into secondary metabolite produets. Moreover, the biosynthesis method is safe, controllable, and economical in contrast to field eultivation of their parent plants. In the past 50 years. 

L-Fucose, 6-deoxy-L-galaclose a component of the blood-group sutetances A, B and O and of various oligosaccharides in human milk, seaweed, plant mucilages. Af, 164, m.p. (a-foim) 140 C, [a] -153 -76 (c = 9). It is also found in various glycosides and antibiotics. Some of the latter also contain D-fu-cose. l-F. is synthesized as its activated derivative, guanosine diphosphate fucose, from GDP-n-mannose by dehydrogenation, isomerization and reduction. 

Reactions (1) and (2) occur during methanol synthesis, while reactions (1), (2), and (4) are essential for the preparation of methane. Except for methane, hydrocarbons undergo dehydrogenation, isomerization, and aromatization under Fischer-Tropsch reaction conditions. These reactions are essentially influenced by the character of the support. 

Catalytic reforming Catalytic cracking Naphtha b.p. 30-190°C H, (6 1) Fractions b.p. 220-540°C 0.3-0.5% Pt on y-AI2O3 promoted by 1% chlorine. Zeolite or + SiO 500-525°C 23.3 atm 500-550°C 1 atm Dehydrogenation Isomerization (Hydrocracking) Carbonium ion reactions (acidic sites) Aromatics Alkanes Gasoline (high olefin content)... 

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