Butadiene ammoxidation

Table 20.3 Summary of results for butadiene ammoxidation with the catalyst V/W/Cr/P/O-TiO2[120]...

Table 20.5 Summary of performance of catalysts reported in [122] for butadiene ammoxidation.

CoUeuille and coworkers [122] investigated catalysts for butadiene ammoxidation which are similar to those also studied in the ammoxidation of benzene (see below). Table 20.5 summarizes the results reported. The main products were fumaronitrile and maleonitrile, cro to nitrile (the unsaturated mononitrile, 1-cyano-propene, with the two trans and cis isomers) and CO with traces of acrylonitrile and furan. The residence time used was very low in this case the best performance was obtained with a typical propene ammoxidation catalyst, made of Bi/Mo/P/O under conditions of low butadiene conversion. 

Some companies are successfully integrating chemo- and biocatalytic transformations in multi-step syntheses. An elegant example is the Lonza nicotinamide process mentioned earlier (.see Fig. 2.34). The raw material, 2-methylpentane-1,5-diamine, is produced by hydrogenation of 2-methylglutaronitrile, a byproduct of the manufacture of nylon-6,6 intermediates by hydrocyanation of butadiene. The process involves a zeolite-catalysed cyciization in the vapour phase, followed by palladium-catalysed dehydrogenation, vapour-pha.se ammoxidation with NH3/O2 over an oxide catalyst, and, finally, enzymatic hydrolysis of a nitrile to an amide. 

Hexamethylenediamine (HMDA), a monomer for the synthesis of polyamide-6,6, is produced by catalytic hydrogenation of adiponitrile. Three processes, each based on a different reactant, produce the latter coimnercially. The original Du Pont process, still used in a few plants, starts with adipic acid made from cyclohexane adipic acid then reacts with ammonia to yield the dinitrile. This process has been replaced in many plants by the catalytic hydrocyanation of butadiene. A third route to adiponitrile is the electrolytic dimerization of acrylonitrile, the latter produced by the ammoxidation of propene. 

V-containing silicalite, for example, has been shown to have different catalytic properties than vanadium supported on silica in the conversion of methanol to hydrocarbons, NOx reduction with ammonia and ammoxidation of substituted aromatics, butadiene oxidation to furan and propane ammoxidation to acrylonitrile (7 and references therein). However, limited information is available about the characteristics of vanadium species in V-containing silicalite samples and especially regarding correlations with the catalytic behavior (7- 6). 

Many substances can be partially oxidized by oxygen if selective catalysts are used. In such a way, oxygen can be introduced in hydrocarbons such as olefins and aromatics to synthesize aldehydes (e.g. acrolein and benzaldehyde) and acids (e.g. acrylic acid, phthalic acid anhydride). A selective oxidation can also result in a dehydrogenation (butene - butadiene) or a dealkylation (toluene -> benzene). Other molecules can also be selectively attacked by oxygen. Methanol is oxidized to formaldehyde and ammonia to nitrogen oxides. Olefins and aromatics can be oxidized with oxygen together with ammonia to nitriles (ammoxidation). 

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 oxide is an important component in catalysts used in a number of industrially important processes. Table I shows some notable examples which include iron molybdate catalysts in selective oxidation of methanol to formaldehyde, ferrite catalysts in selective oxidative dehyrogenation of butene to butadiene and of ethylbenzene to styrene, iron antimony oxide in ammoxidation of propene to acrylonitrile, and iron chromium oxide in the high temperature water-gas shift reaction. In some other reactions, iron oxide is added as a promoter to improve the performance of the catalyst. 

In 1959, Idol (2), and in 1962, Callahan et al. (2) reported that bismuth/molybdenum catalysts produced acrolein from propylene in higher yields than that obtained in the cuprous oxide system. The authors also found that the bismuth/molybdenum catalysts produced butadiene from butene and, probably more importantly, observed that a mixture of propylene, ammonia, and air yielded acrylonitrile. The bismuth/molybdenum catalysts now more commonly known as bismuth molybdate catalysts were brought to commercial realization by the Standard Oil of Ohio Company (SOHIO), and the vapor-phase oxidation and ammoxidation processes which they developed are now utilized worldwide. 

Acrylonitrile (CH2=CH-CN) was made from acetylene and HCN until the 1960s. Today it is made by direct ammoxidation of propylene. Its major use is in making polyacrylonitrile, which is mainly converted to fibers (Orion). It is also copolymerized with butadiene and styrene to produce high impact plastics. 

The production of butadiene is discussed in the diene section Polybutadiene. Although several routes have been developed to produce acrylonitrile, almost all now is produced by the catalytic fluidized-bed ammoxidation of propylene. 

Interestingly, the by-product in the above-described hydrocyanation of butadiene, 2-methylglutaronitrile, forms the raw material for the Lonza process for nicotinamide (see earlier) [123]. Four heterogeneous catalytic steps (hydrogenation, cyclisation, dehydrogenation and ammoxidation) are followed by an enzymatic hydration of a nitrile to an amide (Fig. 1.50). 

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. 

In the case of n-butane the yield was lower owing to the lower hydrocarbon conversion, but the selectivity remained close to 50% (46%). In this case, vanadium played the additional role of oxydehydrogenation of butane to butenes. The reactivity of butene was lower than that of butadiene (both were higher than that of n-butane) which indicates that the mechanism requires the oxy-dehydrogenation of butene to yield butadiene, which is the reactive intermediate that undergoes ammoxidation. 

This article therefore seeks to examine in depth just one mixed oxide catalyst, tin-antimony oxide, which has been commercially developed (2-5) for the oxidation of propylene to acrolein as well as for the ammoxidation of propylene to acrylonitrile and the oxidative dehydrogenation of butenes to 1,3-butadiene. A recent book (6) and a subsequent review (7) have shown how little unanimity has been established about the fundamental properties of the material. In particular there seems to be much confusion as to the phase composition, the nature of the cationic oxidation states, the chemical environment of the cations, the charge compensation mechanism, the nature of the active sites, the distortion of the host tin(IV) oxide lattice by the dopant antimony atoms and whether any changes in the catalyst result from the adsorption and catalytic processes. 

The first real characterization of active phases has been made for the high temperature polymorph of CoMoO (called (a) by us and later (b) by other authors) in the selective oxidation of butane to butadiene (20,21), as well as for (22) and bismuth molybdates (23,24) for oxidation, and ammoxidation of propylene. Additional examples include solid solutions such as (Mo V. )90t (with 0benzene conversion to maleic anhydride (25,26 and the solid solution up to 15% of Sb O in the SnO -Sb O system for propylene oxidation to acrolein (14,2/). 

Supported metal oxides are currently being used in a large number of industrial applications. The oxidation of alkanes is a very interesting field, however, only until recently very little attention has been paid to the oxidation of ethane, the second most abundant paraffin (1). The production of ethylene or acetaldehyde from this feed stock is a challenging option. Vanadium oxide is an important element in the formulation of catalysts for selective cataljdic reactions (e. g. oxidation of o-xylene, 1-3, butadiene, methanol, CO, ammoxidation of hydrocarbons, selective catalytic reduction of NO and the partial oxidation of methane) (2-4). Many of the reactions involving vanadium oxide focus on the selective oxidation of hydrocarbons, and some studies have also examined the oxidation of ethane over vanadium oxide based catalysts (5-7) or reviewed the activity of vanadium oxide for the oxidation of lower alkanes (1). Our work focuses on determining the relevance of the specific oxide support and of the surface vanadia coverage on the nature and activity of the supported vanadia species for the oxidation of ethane. 

Desulfurization of petroleum feedstock (FBR), catalytic cracking (MBR or FI BR), hydrodewaxing (FBR), steam reforming of methane or naphtha (FBR), water-gas shift (CO conversion) reaction (FBR-A), ammonia synthesis (FBR-A), methanol from synthesis gas (FBR), oxidation of sulfur dioxide (FBR-A), isomerization of xylenes (FBR-A), catalytic reforming of naphtha (FBR-A), reduction of nitrobenzene to aniline (FBR), butadiene from n-butanes (FBR-A), ethylbenzene by alkylation of benzene (FBR), dehydrogenation of ethylbenzene to styrene (FBR), methyl ethyl ketone from sec-butyl alcohol (by dehydrogenation) (FBR), formaldehyde from methanol (FBR), disproportionation of toluene (FBR-A), dehydration of ethanol (FBR-A), dimethylaniline from aniline and methanol (FBR), vinyl chloride from acetone (FBR), vinyl acetate from acetylene and acetic acid (FBR), phosgene from carbon monoxide (FBR), dichloroethane by oxichlorination of ethylene (FBR), oxidation of ethylene to ethylene oxide (FBR), oxidation of benzene to maleic anhydride (FBR), oxidation of toluene to benzaldehyde (FBR), phthalic anhydride from o-xylene (FBR), furane from butadiene (FBR), acrylonitrile by ammoxidation of propylene (FI BR)... 

The 2-pentenenitrile, 2-methyl-3-butenenitrile, and methylglutaronitrile in Figure 1.1 are by-products of this reaction sequence. duPont is still studying the phosphines used as ligands for the nickel in an effort to find one bulky enough to favor terminal addition only.214 Reduction of the various nitriles leads to the amines in Figure 1.1, including the cyclic ones. The 2,3-dichloro-l,3-buta-diene is probably a by-product in the synthesis of 2-chloro-1,3-butadiene used to make Neoprene rubber. duPont also polymerizes acrylonitrile to prepare poly (acrylonitrile) fiber (Orion). Acetonitrile is obtained as a by-product of the ammoxidation of propylene to produce acrylonitrile (reaction 1.20). 

The production problems with Buna N, which is a copolymer of butadiene and acrylonitrile, required even more tenacity and optimism, but Dr. Bayer was successful in the development of a commercial process for the catalytic hydrocyanation of acetylene for the production of acrylonitrile. This process which was used worldwide for many years has been displaced by the catalytic ammoxidation of ethylene process. 

Ammoxidation catalysis is an industrially important process that is used to manufacture high volume chemical intermediates for a wide range of pol3mier products as well as nitrile chemicals and chemical intermediates for agricultural and pharmaceutical use. Ammoxidation processes are used to produce the two most commercially important nitrile chemicals, acrylonitrile (C3H3N) and HCN. The former is used to make acrylic fibers, Nylon (DuPont), and performance polymers including ABS (acrylonitrile-butadiene-styrene). The latter is used in the manufacture of herbicides, plastic sheets, and Nylon. 

Acrylonitrile is currently the second largest outlet for propylene (after polypropylene). It is used as a monomer for synthetic fibers and acrylic plastics (thermoplastics and food packaging mainly), AS (acrylonitrile-styrene) resins, and ABS (aerylonitrile-butadiene-styrene) thermoplastics, as well as in the synthesis of acrylamide, adiponitrile, and nitrile elastomers. The manufacture of acrylonitrile is exclusively based on the one-step propylene ammoxidation process. Originally developed by Sohio, Standard Oil Company (now part of BP America), the conventional method used since 1957 employs a fluidized-bed reactor and multicomponent catalysts based on Mo-containing mixed-metal oxides. Over the years, the industrial... 

Although the aim of this chapter is to show how a thermodynamic relationship between A and AI allows to predict the type of catalysts needed for a reaction, it is worth recalling that A can be correlated with experimental parameters related to catalysis, or values of selectivity, provided the same reaction is studied [33]. For example, by using data proposed by Matsuura [60], the heat of adsorption A//ads for a series of catalysts of oxidation of 1-butene to butadiene, or the Mossbauer quadruple shift values for Fe +-containing catalysts of propene ammoxidation, could be related to the A value of the respective catalysts [33]. In a study of the ODH... 

The catalyst is similar for all three steps, and consists of a zero valent nickel phosphite complex, promoted with zinc or aluminium chlorides. The direct addition of hydrogen eyanide to butadiene is particularly attractive with the availability of by-product hydrogen cyanide form the manufactnie of acrylonitrile by the ammoxidation of propylene. 

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