Iodine is known to be an efficient promoter for the oxidative dehydrogenation of a wide variety of hydrocarbons. However, because of its high cost attempts have been made to reduce or eliminate it from the reaction system while still achieving high product yields. Theoretical considerations (thermodynamic and mechanistic) will be presented to show that it should be possible to use sulphur alone or together with chlorine and/or bromine in place of iodine or iodine/halogen mixtures in the oxidative dehydrogenation of different hydrocarbons. These considerations indicate that high product yields should also be possible with the new system if suitable catalysts are used.

The H2S promoted oxidative dehydrogenation of butane to butadiene can be efficiently carried out if a molten salt medium, e.g. LiCl/KCl, is used to dissipate the heat from the highly exothermic reaction. The reaction is catalyzed by the addition of soluble salts such at Tl2O3, BaCl2 or MnCl2. Optimization of reaction conditions by varying temperature, space velocity and quantity of promoter results in a 53% olefin yield (5% butenes, 48% butadiene) at 80% butane conversion. The system is also shown to be efficient for the dehydrogenation of ethane to ethylene, propane to propylene, butene to butadiene and ethylbenzene to styrene.

An experimental program was carried out to determine the effectiveness of H2S/mixed halogen promoters in the oxidative dehydrogenation reaction. Using the butene‐1 to butadiene reaction as an example it was found that while H2S or any of the hydrogen halides alone could be used as the promoter, superior conversions and selectivities (80–85%) were obtained when H2S was used in admixture with the halogens, preferably HCl and/or HBr. The effect of different catalysts and some processing variables (temperature, space velocity) on the desired reaction will be presented.

It has been demonstrated that SO2 acts as an efficient dehydrogenation agent in the conversion of ethylbenzene to styrene in the presence of alkali and alkaline earth metal oxide doped alumina and titania catalysts. Development of these catalysts, which give styrene yields of greater than 80% per pass, is described in the paper. The catalysts allow the use of close to stoichiometric amounts of sulphur dioxide, are active in the presence of steam diluent and show low deactivation with time. The effect of varying process conditions such as temperature, reactant concentration and diluent amount is also described.

A new technique, recently defined, uses an H2S/O2 mixture to selectively dehydrogenate hydrocarbons in high yields at temperatures of about 1100°F in the presence of suitable catalysts. In the new processing scheme, H2S is thought to react with oxygen to form reactive sulphur species capable of efficient hydrogen abstraction. The overall effect is thus the reaction between oxygen and hydrogen from the hydrocarbon to produce water and a more unsaturated hydrocarbon product. The above technique is discussed in some detail for the oxidative dehydrogenation of butenes to butadiene. The importance of selecting the appropriate catalyst is emphasized and the various processing variables affecting the overall reaction are described.