Butene oxidative dehydrogenation

Catalytic properties in the reactions of carbon monoxide oxidation (all oxides) and butene oxidative dehydrogenation (iron oxides) were studied using a microreactor with the vibrofluidized bed of catalysts and pulse/flow kinetic installation [4], Catalytic activities were characterized by the reaction rate W (molec. COWs) in differential conditions and first-order rate constant K (dm butene (STP) /m -s-atm), respectively. 

Oxydehydrogenation of /i-Butenes. Normal butenes can be oxidatively dehydrogenated to butadiene in the presence of high concentration of steam with fairly high selectivity (234). The conversion is no longer limited by thermodynamics because of the oxidation of hydrogen to water. Reaction temperature is below about 600°C to minimise over oxidation. Pressure is about 34—103 kPa (5—15 psi). 

The reaction scheme is rather complex also in the case of the oxidation of o-xylene (41a, 87a), of the oxidative dehydrogenation of n-butenes over bismuth-molybdenum catalyst (87b), or of ethylbenzene on aluminum oxide catalysts (87c), in the hydrogenolysis of glucose (87d) over Ni-kieselguhr or of n-butane on a nickel on silica catalyst (87e), and in the hydrogenation of succinimide in isopropyl alcohol on Ni-Al2Oa catalyst (87f) or of acetophenone on Rh-Al203 catalyst (87g). Decomposition of n-and sec-butyl acetates on synthetic zeolites accompanied by the isomerization of the formed butenes has also been the subject of a kinetic study (87h). 

Ziman et al. [Kinetika i Kataliz, 9 (117), 1968] have studied the kinetics of the catalytic oxidative dehydrogenation of various butene isomers to form 1,3-butadiene. Over a Bi-Mo catalyst the following reactions are important. 

Feed enters the reactor at tube side, oxygen at shell side. Oxidative dehydrogenation of 1-butene to butadiene. W3Sb203 catalyst placed in the pores of the tube. T 462 C. Conversion 30%, Selectivity 92%. T = 505°C. Conversion 57%, Selectivity 88%. ... 

Liaw, B.J. Cheng, D.S. Yang, B.L. (1989) Oxidative dehydrogenation of 1-butene on iron oxyhydroxides and hydrated iron oxides. J. Catalysis 118 312-326... 

A reaction of particular relevance with respect to applied catalysis is the oxidative dehydrogenation (ODH) of hydrocarbon by VmOn ions according to reaction 2, which involves a two-electron reduction of the cluster. By means of a systematic study of the reactions of various YmOn ions as well as the related oxo-vanadium hydroxides VmO H+ ions with a set of C4-hydrocarbons, it was demonstrated recently that the ODH activity of the cluster ions shows a clear correlation with the formal valence of vanadium in the cluster ions with a maximum reactivity for formal vanadium (V) (Fig. 3) [84]. In such a kind of reactivity screening, it is essential to include more than a single reagent as a probe for the reactivity of the different ions in order to reduce interferences by kinetic barriers of one particular combination of neutral and ionic reactants [85]. Accordingly, the sums of the relative rate constants for the ODH reactions of the four different butenes are considered and normalized to the most reactive ion studied, which turns out to be the formally pure vanadium (V) compoimd In addition to isomeric... 

The oxidation of olefins has also been investigated on a-Mo03 supported on carbon the mild oxidation of propene into acrolein takes place mainly on the (100) face of a-Mo03 while total oxidation occurs on the (010) face (425fg). Similar results have been obtained for the oxidative dehydrogenation of 1-butene into butadiene (425h). 

M-butane proceeds via an intermolecular mechanism with 2-butene involved intermediately.300-303 The role of the transition metal promoters such as Fe and Mn was shown to increase the surface concentration of the intermediate butene 304 The formation of butene is speculated to occur through an oxidative dehydrogenation on the metal site305 or by one-electron oxidation.306... 

Other catalysts for alkane oxidative dehydrogenation have also been reported in the patent literature. For example, it was claimed that a Na and Li phosphomolybdate produced 17% butadiene and 5% butenes at 600°C with a 1 1 mixture of butane and oxygen (13). 

Fig. 6. Dependence of selectivity for oxidative dehydrogenation of butane (to butenes and butadiene) on the reduction potential of the cations in orthovanadates of the formula M2 (V04)2 and M11V04. Reactions conditions 500°C, butane conversion = 12.5%, butane 02 He = 4 8 88 (from Ref. 39).

The dehydrogenation of butenes to butadiene is the most selective butene oxidation process and has received considerable attention in the... 

Abd. El-Salaam et al. [1] have studied the catalytic activity of various bismuth molybdates for the oxidative dehydrogenation of 2,5-dihydro-furan to furan. A close correlation with the oxidation of butene to butadiene is expected and was indeed observed. 

Selective Oxidative Dehydrogenation of Butenes on Ferrite Catalysts... 

Oxidative dehydrogenation of butene 573-648 a-Fe203, a-Fe203/Si02 Selectivity for butadiene increases with decreasing Fe2Q3 crystallite size 54... 

Hydroxypyrrole itself (43) has only been obtained [76ZN(B)599] so far by the room temperature mercuric oxide dehydrogenation of 1-hydroxy-3-pyrroline (41), prepared as outlined from Z-l,4-dichloro-2-butene. The presumed first-formed tautomer 42 was not detected. 

Batist et al. (36) measured the rate of oxidative dehydrogenation of 1-butene in the presence of oxygen and the rate of catalyst (Bi2Mo06) reduction with 1-butene and found the rates and product distribution to be almost the same. From this they concluded that the rate of reaction is... 

Table II. Oxidative dehydrogenation of butene to butadiene on ZnFe204 and a 50/50 mixture of ZnFe204 + a-Sb204...

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