Regeneration of catalysts used in oxidative dehydrogenation of alkylaromatics and paraffins

A regenerative process for the preparation of olefinically unsaturated compounds by oxidation of selectively oxidizable hydrocarbons at a temperature T.sub.react over oxygen carrier acting as catalyst, in the absence of molecular oxygen, alternating (in repeated cycles) with regeneration of the spent oxygen carrier with a gaseous molecular oxidizing agent, characterized by the following steps:

• the spent (reduced) catalyst is cooled, prior to the introduction of the regenerative gas either still in the presence of the reaction mixture having a reducing action, or under a blanket of inert gas, to a temperature T.sub.reg, which is below the temperature of the reaction T.sub.react ;
• regeneration is started at temperature T.sub.reg by the introduction of the oxidizing agents, regeneration being controlled in such a manner that the highest temperature occurring during regeneration does not exceed the temperature of reaction T.sub.react,0 at which oxidation/dehydrogenation is commenced;
• and
• following the removal of the oxidizing environment, the regenerated catalyst is heated to the initial reaction temperature T.sub.react,0 and only then is the hydrocarbon (educt) to be oxidized introduced.