Oxidative dehydrogenation of n-butane: a comparative study of thermal and catalytic reaction using Fe-Zn mixed oxides

The thermal cracking of n-butane was compared with both thermal and catalyt ic n-butane oxidative dehydrogenation reactions. It was found that thermal oxidative dehydrogenation of n-butane was highly selective to n-butenes (ap proximately 70%) in the conversion range of 11-20%. This reaction proceeded at lower temperature than the thermal cracking of n-butane without oxygen. These results suggest that both reactions have different initiation steps. In the thermal cracking of n-butane the reaction initiated by the C-C bond scission, whereas for the thermal oxidative dehydrogenation of n-butane th e removal of the hydrogen atom by the molecular oxygen to form (C) over dot (4)H(9) and H(O) over dot(2) radicals was proposed as the main initiation s tep. On the other hand, butadiene was only obtained via a catalytic pathway , being strongly dependent on the reaction conditions.