Normal butenes to butadiene, furan and maleic anhydride

2 Normal butenes to butadiene, furan and maleic anhydride 

The dehydrogenation of butenes to butadiene is the most selective butene oxidation process and has received considerable attention in the 

Deeper oxidation products like furan and, particularly, maleic acid anhydride, can be produced by catalysts that have a stronger oxidative power than the above type-(a) catalysts, but, at the same time, have retained the capacity to transfer oxygen selectively to the organic molecule (a capacity which is absent in the type-(b) catalysts). Besides, a more acidic character of the catalyst surface is probably required to produce an acidic product like maleic anhydride effectively. The most interesting catalysts of this group are V2Os-based catalysts and certain molybdates and Mo03-based catalysts. 

There is no strict distinction between mild catalysts that produce mainly butadiene and the stronger oxidizing catalysts that can yield maleic anhydride. The reaction conditions are also an important factor. The contributions are classified, therefore, according to the catalysts studied, instead of a division with respect to the main product that is formed. 

Steam may have a positive effect on the activity according to Komaro-vskii et al. [179], A doubling of the reaction rate was observed by adding up to 20% steam to the oxidation of a mixture of n-butenes in a flow reactor over a Bi/Mo catalyst of unknown composition at 420—480°C. The same authors [179] also studied the influence of the oxygen concentration, which was found to have no effect on the kinetics at 02/butene 0.4. Furthermore, a rather complex set of kinetic equations was derived to describe side reactions (isomerization, and formation of carbonyls, acids and furan). 

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