Butanediols dehydrogenation

The efficiency of zinc-chromium and vanadium-magnesium oxide catalysts in the reaction of butanediol dehydrogenation has been established. The optimum reaction conditions in butadione synthesis providing high yields and selectivity have been found. Experimental substantiation of principles for the purposeful synthesis of the catalytic systems mentioned above is considered. The catalysts were prepared based on these principles. 

We have investigated a series of the dehydrogenating catalysts for this reaction. Our attention was focused on two of them. Further study of 2,3-butanediol dehydrogenation and oxidative dehydrogenation to butadione was performed using zinc-chromium oxide catalysts and vanadium-magnesium oxide catalysts as well. 

With various catalysts, butanediol adds carbon monoxide to form adipic acid. Heating with acidic catalysts dehydrates butanediol to tetrahydrofuran [109-99-9] C HgO (see Euran derivatives). With dehydrogenation catalysts, such as copper chromite, butanediol forms butyrolactone (133). With certain cobalt catalysts both dehydration and dehydrogenation occur, giving 2,3-dihydrofuran (134). 

Heating butanediol or tetrahydrofuran with ammonia or an amine in the presence of an acidic heterogeneous catalyst gives pyrroHdines (135,136). With a dehydrogenation catalyst, one or both of the hydroxyl groups are replaced by amino groups (137). 

Butyrolactone. y-Butyrolactone [96-48-0] dihydro-2(3H)-furanone, was fkst synthesized in 1884 via internal esterification of 4-hydroxybutyric acid (146). In 1991 the principal commercial source of this material is dehydrogenation of butanediol. Manufacture by hydrogenation of maleic anhydride (147) was discontinued in the early 1980s and resumed in the late 1980s. Physical properties are Hsted in Table 4. 

Ma.nufa.cture. Butyrolactone is manufactured by dehydrogenation of butanediol. The butyrolactone plant and process in Germany, as described after World War II (179), approximates the processes presendy used. The dehydrogenation was carried out with preheated butanediol vapor in a hydrogen carrier over a supported copper catalyst at 230—250°C. The yield of butyrolactone after purification by distillation was about 90%. 

Biacetyl is produced by the dehydrogenation of 2,3-butanediol with a copper catalyst (290,291). Prior to the availabiUty of 2,3-butanediol, biacetyl was prepared by the nitrosation of methyl ethyl ketone and the hydrolysis of the resultant oxime. Other commercial routes include passing vinylacetylene into a solution of mercuric sulfate in sulfuric acid and decomposing the insoluble product with dilute hydrochloric acid (292), by the reaction of acetal with formaldehyde (293), by the acid-cataly2ed condensation of 1-hydroxyacetone with formaldehyde (294), and by fermentation of lactic acid bacterium (295—297). Acetoin [513-86-0] (3-hydroxy-2-butanone) is also coproduced in lactic acid fermentation. 

The pattern of commercial production of 1,3-butadiene parallels the overall development of the petrochemical industry. Since its discovery via pyrolysis of various organic materials, butadiene has been manufactured from acetylene as weU as ethanol, both via butanediols (1,3- and 1,4-) as intermediates (see Acetylene-DERIVED chemicals). On a global basis, the importance of these processes has decreased substantially because of the increasing production of butadiene from petroleum sources. China and India stiU convert ethanol to butadiene using the two-step process while Poland and the former USSR use a one-step process (229,230). In the past butadiene also was produced by the dehydrogenation of / -butane and oxydehydrogenation of / -butenes. However, butadiene is now primarily produced as a by-product in the steam cracking of hydrocarbon streams to produce ethylene. Except under market dislocation situations, butadiene is almost exclusively manufactured by this process in the United States, Western Europe, and Japan. 

Butadiene is obtained mainly as a coproduct with other light olefins from steam cracking units for ethylene production. Other sources of butadiene are the catalytic dehydrogenation of butanes and butenes, and dehydration of 1,4-butanediol. Butadiene is a colorless gas with a mild aromatic odor. Its specific gravity is 0.6211 at 20°C and its boiling temperature is -4.4°C. The U.S. production of butadiene reached 4.1 billion pounds in 1997 and it was the 36th highest-volume chemical. ... 

Geminox A direct process for converting butane to 1,4-butanediol. The butane is first oxidized in the gas phase to maleic anhydride, using BP s fluidized bed technology. The maleic anhydride is scrubbed with water and then catalytically dehydrogenated to butanediol. Developed in 1994 by BP Chemicals and Lurgi. Modifications of the process can be used to make tetrahydrofiuan and y-butyrolactone. The first plant will probably be built on BP s site at Lima, OH, for completion in 2000. 

If a diol is oxidatively dehydrogenated to form a diacid via an intermediate with one Off group, then a first order plot based on hydrogen evolution can exhibit some curvature. This is because the slope at any time will reflect the instantaneous concentrations of the diol and intermediate as well as their intrinsic reactivities. First order plots for the reaction of ethylene glycol, 1,4-butanediol and diethanolamine are shown in Figure 2. All plots are reasonably linear, consistent with reaction via an intermediate with a rate constant rather similar to that of the starting diol (or a direct reaction with no intermediate whatsoever). 

Dehydrogenation of 1,3-butanediol to 1,3-butadiene, catalyzed by sodium phosphate on coke... 

Dchydrocyclization of /t-hexane Hydrogenation of carbon dioxide Coupling of butane dehydrogenation and hydrogen oxidation Hydrogenation of cij,rra/w-butene-1,4-diol to c/5.rra/i5-butanediol Hydrogenation of 2-butyne-1,4-diol to ci5,/ran -butenediol... 

Butadiene Synthesis by Dehydrogenation and Oxidative Dehydrogenation of 2,3-Butanediol... 

Among the methods of preparation of butadione the oxidation of 2-butanone is one of the most frequently discussed. Both catalytic end electrochemical methods were used. The conversion of 2-butanone varies from 10 to 84% and the yields of diacetyl do not exceed 40% [2-4]. The heterogeneous dehydrogenation of 2,3-butanediol is an alternative simple method of butadione synthesis [5]. 

In the course of transformation of 2,3-butanediol the products of dehydrogenation of one and two alcohol groups were formed. Thus the reaction results not only in the formation of butadione but in formation of acetoin as well. The amounts of both products formed change markedly with the butanediol conversion degree. 

Dehydrogenation of butanediol on Zn-Cr-oxide catalyst in a wide temperature range allowed to obtain data on the content of acetoin and diacetyl at different conversions of 2,3-butanediol. Besides, the transformation of acetoin into butadione was studied (Figure 1.). One can see that at low temperature (310-340°C) when the conversion was less than 50% mainly acetoin was presented in the reaction products (diacetyl/acetoin molar ratio - 0,5). At 375°C the curve of acetoin content reaches... 

Figure 1. Dehydrogenation of acetoin (to the left, pale dots) and of 2,3-butanediol (to the right) on zinc- chromium oxide catalyst, LHSV=1.6 h" 2, acetoin (as initial material) 3, butadione 1, butanediol (as initial material) 2, acetoin (formed as intermediate from butanediol) 3,butadione.

Oxidative dehydrogenation of butanediol on the selected vanadium-magnesium catalysts allowed to reduce the reaction temperature of butadion synthesis by about 100°C. The reaction was studied in the temperature range of 160 - 350°C at LHSV-equal to 1 h" and butanediol oxygen molar ratio equal to 1 1 (Table 2). Already at 250°C more than 85% of butanediol was converted. 

As in the dehydrogenation on Zn-Cr oxide catalyst, at low butanediol conversion acetoin is formed preferably. At 180°C diacetyl acetoin molar ratio was equal 0.66. Maximum amount of acetoin in the reaction products was observed in the range of 180-220°C. With further increasing temperature the acetoin content declined in favor of diacetyl. This dependence of acetoin content on butanediol conversion allows it to extend the above conclusion of the intermediate formation of acetoin to oxidative dehydrogenation of butanediol on V205/Mg0 catalysts. 

Oxidative dehydrogenation of 2,3-butanediol on Mg-V oxide catalyst, LSHV 1.0 h. ... 

Parameters of the reaction were varied in a broad range temperature 200-420°C, LHSV 0.8-1.6 h", in the oxidative dehydrogenation butanediol oxygen molar... 

Butanediol conversion on Co-Zn/porcelain catalyst is a paralell-consecu-tive process including dehydrogenation, inter- and intramolecular dehydration as well as cyclization ind cracking reactions. The studied catalyst support pretreated with HCl activates the dehydration and cyclization reactions of 1,4-buta-nediol and 4-hydroxybutanal. These reactions result in the formation of tetrahydrofuran and 2,3-dihydrofuran, respectively. 

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