Butadiene oxidative dehydrogenation

Production of styrene from butadiene has also been extensively investigated. Recentiy, Dow announced licensing a process involving cyclodimerization of 1,3-butadiene to 4-vinylcyclohexene, followed by oxidative dehydrogenation of the vinylcyclohexene to styrene (65,66). The cyclodimerization step takes place in... 

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). 

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. 

O-X-D [Oxidative dehydrogenation] A process for converting n-butane to butadiene by selective atmospheric oxidation over a catalyst. Developed by the Phillips Petroleum Company and used by that company in Texas from 1971 to 1976. See also Oxo-D. 

Oxidative Dehydrogenation of Ubutene to Butadiene Nonporous Zr-Y-Ti-bascd membranes... 

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%. ... 

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). 

The Cu+/zeolite-catalyzed cyclodimerization of 1,3-butadiene at 100°C and 7 atm was found to give 4-vinylcyclohexene [Eq. (13.12)] with high (>99%) selectivity. Subsequent oxidative dehydrogenation over an oxide catalyst in the presence of steam gives styrene. The overall process developed by Dow Chemical113 offers an alternative to usual styrene processes based on ethylation of benzene (see Section 5.5.2). 

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).

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. 

The difference in reactivity of the butadiene precursor toward 02 and NzO is interesting. N20 is known to be active in selective oxidation (16). For example, on molybdenum oxide (16) and cobalt magnesium oxide (17), NzO decomposes at room temperature to form an O adsorbed species which is very active in the oxidative dehydrogenation of ethane. The results presented above suggest that the degradation of butadiene precursor on a-iron oxide requires an 02 and not an 0" species. This implies that the degradation proceeds via a peroxide intermediate. 

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

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

Yang, G., Huang, Z., Chen, D., and Zhao, S. Study of Fast Fluidized Bed for Converting Butene to Butadiene by Oxidative Dehydrogenation, Petrochemical Technology (Chinese), vol. 16, No. 10, pp. 680-685. 

Molybdate based scheelites have been intensively studied in this respect, one reason being that they are found with molybdenum in both the penta- and hexavalent state. Bismuth molybdates in particular are useful catalysts for selective oxidation of propylene to acrolein, propylene ammoxidation to acrylonitrile and the oxidative dehydrogenation of butene to butadiene. 

On the basis mainly of results obtained in the oxidation of isobutene to methacrolein, the oxidative dehydrogenation of butene to butadiene and the oxygen-aided dehydration of formamide to nitriles, it was possible to show that oxides present in catalysts are located on a scale reflecting donor-acceptor properties (fig. 5). Some oxides are essentially acceptors (e.g., M0O3, some tellurates) they can potentidly cany active and selective sites, provided they receive spillover oxygen. Others are essentidly donors a-Sb204, in this respect, is typical it produces spillover oxygen but carries no sites active for oxidation. Other oxides have mixed properties. The acceptors are relatively covalent, the donors are more ionic [63,77]. 

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