First propene ammoxidation

The oxidation of propene to acrolein has received much attention for several reasons. Firstly, the process is of industrial importance in itself, and it is also a suitable model reaction for the even more important, but at the same time more complicated, ammoxidation. Secondly, propene oxidation is, in many aspects, representative of that of a class of olefins which possesses allylic methyl groups. Last, but not least, the allylic oxidation is a very successful example of selective catalysis, for which several effective metal oxide systems have been discovered. The subject has therefore attracted much interest from the fundamental point of view. 

The ammoxidation of propene to acrylonitrile is of great industrial importance and accordingly the literature is abundant. The reaction is very similar to the oxidation of propene to acrylonitrile and carried out at the same conditions and over the same kind of catalysts. The famous bismuth phosphomolybdate catalyst developed by Sohio was the first of a series of highly effective mixed-oxide catalysts. The optimum yields are generally obtained at temperatures of 400—500°C. Initial selectivities over 95% and yields up to 80% are feasible. The superior selectivity of the ammoxida-... 

Wise [350] investigated the parallel between ammoxidation and oxidation of ammonia over bismuth molybdates. It was shown that the rate of conversion to nitrogen is first order in NH3 and independent of oxygen concentration, analogous to the selective oxidation of propene. Under conditions in which propene combusts, NH3 is converted to nitrogen oxides. 

The porous titanium silicate TS-1 represents one of the great commercial successes of recent years. Despite only being reported for the first time in the last decade, it is already established as an oxidation catalyst in the manufacture of hydroquinone, and processes based on its use as a catalyst in the epoxidation of propene and the ammoxidation of cyclohexanone are near the production stage.14 The use of the increasingly diverse range of molecular sieve solid catalysts is also described in Chapter 2. 

Red-ox type catalysts are mostly used in oxidation or related types of reactions. For instance, vanadium catalysts containing ions of different valence state are used in the oxidation of benzene to maleic anhydride. Bismuth molybdate catalyst can be used both for the oxidation or ammoxidation of propene. Anchored metal-complex catalysts combine the advantage of both homogeneous and heterogeneous catalysts, however in these catalysts the molecular character of the active sites is maintained. In the last generation of this type of catalysts, heteropolyacids are fixed first to the support and in the second step different metal-complexes are anchored to the heteropolyacid. In this way highly active and stable catalyst have been prepared for different reactions. ... 

Idol first reported in 1959 that bismuth molybdenum oxides, compounds found in the Sohio patents for ammoxidation of propene to acrylonitrile, selectively oxidize propene to acrolein. Since that original discovery, Monsanto has developed its own proprietary catalyst composition for ammoxidation of propene to acrylonitrile. 

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