Catalytic ammoxidation

Ben2onitrile can be produced in high yield by the vapor-phase catalytic ammoxidation of toluene (76) ... 

A two-step process involving conventional nonoxidative dehydrogenation of propane to propylene in the presence of steam, followed by the catalytic ammoxidation to acrylonitrile of the propylene in the effluent stream without separation, is also disclosed (65). 

Nicotinic acid and nicotinamide, members of the vitamin B group and used as additives for flour and bread enrichment, and as animal feed additive among other applications, are made to the extent of 24 million pounds (nearly 11 million kilograms) per year throughout the world. Nicotinic acid (pyridine-3-caiboxylic acid), also called niacin, has many uses. See also Niacin. Nicotinic acid is made by the oxidation of 3-picolme or 2-mcthyl-5-cthylpyridine (the isocinchomcnc acid produced is partially deearboxylated). Alternatively, quinoline (the intermediate quinolinic acid) is partially deearboxylated with sulfuric add in the presence of selenium dioxide at about 300° C or with nitric acid, or by electrochemical oxidation. Nicotinic acid also can be made from 3-picoline by catalytic ammoxidation to 3-cyanopyridine, followed by hydrolysis. 

I 20 Catalytic Ammoxidation of Hydrocarbons on Mixed Oxides lOOi---------------- ------- --------------------... 

Scheme 20.1 Synthesis of aromatic nitriles by catalytic ammoxidation.

Typical performance is a selectivity higher than 90% at a conversion in the 50-90% range, mainly depending on the type of substrate. Substituted pyridines yield better selectivities at high conversion than the equivalent alkylaromatics. The nature and position of the substituents in substituted alkylaromatics also play an important role in determining selectivity and activity. The commercial application of this technology is mainly hindered by the relatively small plant necessary for these products as compared to full-scale processes. The further implementation of the process of alkylaromatic catalytic ammoxidation would thus require the development of multi-purpose small-size continuous plants using small fluidized bed-reactors (to better control temperature and allow easier substitution of the catalyst). 

Aromatic imides are another type of product which can be synthesized by catalytic ammoxidation. o-Xylene is converted over vanadium-titanium oxide catalysts to tolunitrile and then, depending on catalyst composition and reaction conditions, phthalimide or phthalonitrile can be selectively synthesized (Scheme 20.3) [94]. 

Acetonitrile can be produced by catalytic ammoxidation of ethane and propane over Nb-Sb mixed oxides supported on alumina, with selechvities to acetonitrile of about 50-55% at alkane conversions of around 30% [133]. In both cases, CO forms in approximately a 1 1 molar ratio with acetonitrile, owing to a parallel reaction from a common intermediate. When feeding n-butane, the selectivity to acetonitrile halves. Bondareva and coworkers [134] also studied ethane ammoxidation over similar types of catalyst (V/Mo/Nb/O). 

Figure 5. Response signal eirea of pulse catalytic ammoxidation experiments on prereducedZ-oxidized (VO>2P207 catalyst.

Response signal area (a.u.) of N-benzonitrile and N-benzonitrile during pulse catalytic ammoxidation of toluene on pure a-(NH4)2(V0)3(P207>2 and NHs-containing ammoxidation feed. 

This catalytic ammoxidation process was truly revolutionary. Since the introduction of this technology, INEOS has developed and commercialized several improved catalyst formulations. These catalyst advancements have improved yields and efficiencies vs. each prior generation to continually lower the cost to manufacture acrylonitrile. INEOS continues to improve upon and benefit from this long and successful history of catalyst research and development. In fact, many of INEOS s licensees have been able to achieve increased plant capacity through a simple catalyst changeout, without the need for reactor or other hardware modifications. INEOS s catalyst system does not require changeout overtime, unless the licensee chooses to introduce one of INEOS s newer, more economically attractive catalyst systems. 

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