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Keywords:

  • bromine;
  • halogens;
  • iodine;
  • propylene;
  • oxidative dehydrogenation

Abstract

Oxidative dehydrogenation is a promising way to produce olefins, diolefins and aromatics. However, the product yield is limited by the consecutive oxidation of the product to oxygenated products. The highest yield reported for propane oxidative dehydrogenation is only about 30 %. Alternatively, halogens can be used as oxidants in oxidative dehydrogenations. Although the iodine process is highly selective, it requires very high reaction temperatures (≈900 K) to give a good yield of C3H6+C3H7I, and iodine is too expensive for industrial deployment. Bromine is a more reactive oxidant but less selective towards C3H6 and C3H7Br. We show that the use of bromine–iodine mixtures with low iodine content (no greater than 20 %) results in up to 80 % of C3H6+C3H7X single-pass yield at moderate reaction temperatures (<800 K). The results are promising for developing a low temperature on-purpose propylene technology. Furthermore, the underlying chemistry might be extended to the synthesis of many other commercially desirable unsaturated hydrocarbons.