Dehydrogenation, of 1-butene

The following simple example by Wohlfahrt [21] which demonstrates the effect on selectivity for an industrial reaction it is based on an experimental investigation by Voge and Morgan [22]. 

The dehydrogenation of n-butenes, diluted with steam, on a Shell 205 catalyst can be described approximately by two first-order reactions in series (A B C)  

The fraction of butadiene beyond the maximal concentration diffiises to the interior of the catalyst pellet and is lost. Thus the selectivity, given by Equation 8.27 amounts to 52% only. By decreasing the active layer of the catalyst to one-fifth of the original value, transport of butadiene from the point of maximum concentration to the pellet interior can be stopped, and selectivity is raised to 85 %. 

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Butadiene. Although butadiene was produced in the United States in the eady 1920s, it was not until the start of Wodd War 11 that significant quantities were produced to meet the war effort. A number of processes were investigated as part of the American Synthetic Rubber Program. Catalytic dehydrogenation of / -butenes and / -butanes (Houdry process) and thermal cracking of petroleum hydrocarbons were chosen (12). 

In the petroleum (qv) industry hydrogen bromide can serve as an alkylation catalyst. It is claimed as a catalyst in the controlled oxidation of aHphatic and ahcycHc hydrocarbons to ketones, acids, and peroxides (7,8). AppHcations of HBr with NH Br (9) or with H2S and HCl (10) as promoters for the dehydrogenation of butene to butadiene have been described, and either HBr or HCl can be used in the vapor-phase ortho methylation of phenol with methanol over alumina (11). Various patents dealing with catalytic activity of HCl also cover the use of HBr. An important reaction of HBr in organic syntheses is the replacement of aHphatic chlorine by bromine in the presence of an aluminum catalyst (12). Small quantities of hydrobromic acid are employed in analytical chemistry. 

Selectivity among butylene isomers also occurs in vapor-phase heterogeneous catalysis, at least in the case of dehydrogenation of butenes to butadiene, where maximum yields can be obtained by employing slightly different conditions for each isomer (18). In practice, mixtures of isomers are used and an average set of conditions is employed. 

Manufacture Some of the butadiene produced is recovered from steam crackers along with ethylene and propylene. However, most of it is now produced by the dehydrogenation of butene. CH3 CH-CH-CH3 CH2-CH-CH-CH2 + H2... 

Butadiene can be produced by the dehydrogenation of butene over an appropriate catalyst. 

For the dehydrogenation of butene-1 to butadiene the heat of reaction at 298 K is AHrj2g8 = +26360 cal/gmol and the heat capacity difference is... 

Dehydrogenation of Butene to Butadiene Nonporous Pd membranes Gryaznov et al. (1970)... 

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

Several antimony-based oxide combinations are very good catalysts for the dehydrogenation of butene to butadiene. Attention has particularly been paid to the three binary oxide combinations that are well known for their propene ammoxidation qualities Sn—Sb—O, Fe—Sb—O and U—Sb—O. 

Iron-based oxide mixtures, e.g. ferrites, and supported iron oxides can be very effective catalysts for the dehydrogenation of butene to butadiene, as also appears from the patent literature [160],... 

Maissant et al. [194] used a Bi203 Mo03 = 1 2 catalyst at 450°C to convert l-methyl-2-butene and 2-methyl-2-butene into isoprene. A selectivity of 37% was reached with an activity about 10 times as large as the dehydrogenation of butene with the same catalyst under comparable conditions. Trimethyl-2,2,3-butene-l gave 75% of ferf-butylacrolein. 

With respect to the reaction products, the catalysts can be classified into three groups. The first group is very acidic in nature (Bi/Mo = 0—0.3) and converts olefins to acidic products (e.g. butene to maleic anhydride), the second group has medium acidity (Bi/Mo = 0.5—3) and provides the optimal conditions for the dehydrogenation of butene to butadiene, while the third group (Bi/Mo > 3), which has a basic character, only forms combustion products. 

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... 

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

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