Oxidative Dehydrogenation of n-Butane

I 6 Photoelectron Spectroscopy of Catalytic Oxide Materials 63.2.2 Oxidative Dehydrogenation of n-Butane... 

Catalysts 1 and 2, that are 0.4 and 0.8 % CoNx/y-AbOs, indicate similarly high performances in oxidative dehydrogenation of n-butane. Even at 400°C, the conversion exceeded 40 % (Fig. 1) and yield of olefins reached 25 %. The special feature of this catalyst consists of a high conversion of n-butane yielding mostly light olefins, ethylene and propylene. 90 wt% of olefins formed at 400°C and molar ratio Oj/n-butane of 1.5, were C2-C3 olefins 53 wt.% was ethylene and the rest propylene. 

Milne, A.D., 2008. The Apphcation of the Attainable Region Concept to the Oxidative Dehydrogenation of N-butanes in Inert Porous Membrane Reactors. University of the Witwatersrand, Johannesburg. 

Milne, D., Seodigeng, T., Glasser, D., Hildebrandt, D., Haus-berger, B., 2009. Candidate attainable regions for the oxidative dehydrogenation of n-butane using the recursive constant control (RCC) policy algorithm. Ind. Eng. Chem. Res. 48, 5211-5222. 

Soler J., Ldpez Nieto J.M., Herguido J., Menendez M. and Santamarfa J. (1998). Oxidative dehydrogenation of n-butane on V/MgO catalysts. Influence of the type of contactor, Catal. Letters, 50, pp. 25-30. 

Lopez Nieto, J., Concepdon, P, Dejoz, A., et al. (2(X)0). Oxidative Dehydrogenation of n-Butane and 1-Butene on Undoped and K-Doped VOX/AI2O3 Catalysts, Catal Today, 61, pp. 361-367. 

Raju G, Reddy BM, Park SE (2014) CO2 promoted oxidative dehydrogenation of n-butane over V0j/M02-Zr02 (M = Ce or Ti) catalysts. J CO2 Util 5 41 6... 

Urlan F, Marcu IC, Sandulescu I (2008) Oxidative dehydrogenation of n-butane over titanium pyrophosphate catalysts in the presence of carbon dioxide. Catal Commun 9 2403-2406... 

Blasco T, Nieto JML, Dejoz A, Vazaquez MI (1995) Inllucaice of the acid-base character of supported vanadium catalysts on their catalytic properties for the oxidative dehydrogenation of n-butane. J Catal 157 271-282... 

Madeira LM, Aranda RMM, Hodar FJM, Fierro JLG, PtHtela MF (1997) Oxidative dehydrogenation of n-butane over alkali and alkaline earth-pnunoted a-NiMo04 catalysts. J Catal 169 469-479... 

Bhattacharya, D., Bej, S.K., and Rao, M.S. Oxidative dehydrogenation of n-butane to butadiene effect of different promoters on the performance of vanadium-magnesium oxide catalysts. Appl Catal A Gen. 1992,87, 29. 

Oxidative Dehydrogenation of n-Butane in a Porous Membrane Reactor... 

The oxidative dehydrogenation of n-butane to butane and butadiene is accompanied by side-reactions of deep oxidation of products and reactant to CO and CO2. The reaction network is shown in Figure 9.5. 

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). 

VO)2P207 is superior for the selective dehydrogenation of n-butane to butene to other crystalline V-P oxides, while few differences exist between the oxidation of butene and butadiene, which are considered reaction intermediates. The abstraction of methylene hydrogen from n-butane is the slowest step. Hence this step determines the overall catalytic activity." 2) Selectivity in forming anhydride from C4 and C5 alkanes, but not in selective oxidation of lower (C2 and C3) or higher (Ce-Cg) alkanes." 3) The number of surface layers involving the catalytic reactions is limited to 2-3 in contrast to Bi-Mo-O catalysts. 

This problem is highlighted in the case of an alumina-supported vanadium catalyst employed for the dehydrogenation of n-butane. The hydrocarbon creates a reducing environment, which results in a reduction in the oxidation state of... 

MTBE is produced by reacting methanol with isobutene. Isobutene is contained in the C4 stream from steam crackers and from fluid catalytic cracking m the crude oil-refining process. However, isobutene has been in short supply in many locations. The use of raw materials other than isobutene for MTBE production has been actively sought. Figure 2 describes the reaction network for MTBE production. Isobutene can be made by dehydration of i-butyl alcohol, isomerization of -butenes [73], and isomerization and dehydrogenation of n-butane [74, 75]. t-Butanol can also react with methanol to form MTBE over acid alumina, silica, clay, or zeolite in one step [7678]. t-Butanol is readily available by oxidation of isobutane or, in the future, from syngas. The C4 fraction from the methanol-to-olefins process may be used for MTBE production, and the C5 fraction may be used to make TAME. It is also conceivable that these... 

The -butene feed was supplied by the dehydrogenation of n-butane and the plant began the trend to develop oxidation processes using aliphatic petrochemical hydrocarbons. The main incentive, of course, was to use surplus C4 hydrocarbon from steam cracking. This not only used a cheap by-product gas, but the reaction was less complicated because the straight-chain C4 molecule contained fewer carbon atoms tlm aromatic benzene. 

Methyl ethyl ketone is made mostly by the dehydrogenation of 5ec-butyl alcohol. A small amount is isolated as a by-product in acetic acid production by the oxidation of n-butane. 

Over the years the range of uses of the K-L model has been extended to chemical processes that can not be described by first order kinetics. For these problems no anal3dical solution can be obtained so the resulting set of DAE equations are solved numerically. Gascon et al [48], for example, investigated the behavior of a two zone fluidized bed reactor for the propane dehydrogenation and n-butane partial oxidation processes emplo3ung the K-L model framework. 

As the olefins and to a lesser extent the alkanes are basic one may expect the desorption to be favored by surface basic sites. In other words oxidative dehydrogenation of alkanes is expected to be easier on surface exhibiting basic properties. As a matter of fact the results given in table 5 from ref 41 show that Mg2V207 which is more basic as shown in table 4 is more selective for olefins in propane conversion and to a lesser extent for n-butane and isobutane oxidation reactions than the other two phases. Such a feature is even more pronounced for the samples with excess MgO at least for propane oxidation, samples which were also shown to present higher basicity (table 4). 

Catalytic data for oxidative dehydrogenation of propane (A) n-butane (B) and isobutane (C) at 540°C (from ref 41). 

To promote both the conversion of reactants and the selectivity to partial oxidation products, many kinds of metal compounds are used to create catalytically active sites in different oxidation reaction processes [4]. The most well-known oxidation of lower alkanes is the selective oxidation of n-butane to maleic anhydride, which has been successfully demonstrated using crystalline V-P-O complex oxide catalysts [5] and the process has been commercialized. The selective conversions of methane to methanol, formaldehyde, and higher hydrocarbons (by oxidative coupling of methane [OCM]) are also widely investigated [6-8]. The oxidative dehydrogenation of ethane has also received attention [9,10],... 

Supported vanadium oxides have been proposed as selective catalysts in partial oxidation reactions [1] and more specifically in the oxidative dehydrogenation (ODH) of short chain alkanes [2, 3]. However, it has been observed that the catalytic behavior of these catalysts during the oxidation of alkanes depends on the vanadium loading and the acid-base character of metal oxide support. In this way, alumina-supported vanadia catalysts with low V-loading are highly active and selective during the ODH of ethane [4-7] and propane [8] but they show a low selectivity in the ODH of n-butane [4, 5, 9, 10]. 

This part of the analysis dll be restricted to the oxidative dehydrogenation of ethane, propane and n-butane. The corresponding selectivity conversion plots are presented in figure 4. 

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