Process for simultaneously cracking heavy hydrocarbons into light oils and producing hydrogen

A process for simultaneously cracking heavy hydrocarbons to form light oils and producing hydrogen, which comprises

• a first step wherein steam and heavy hydrocarbons are simultaneously contacted with a catalyst in a reduced state, containing at least 30% by weight iron in the form of iron oxide, at a temperature of from 500.degree. to 800.degree. C., to produce hydrogen, cracked gases, and cracked light oils, to convert the reduced state catalyst into an oxidized-state catalyst, and to deposit coke on the catalyst, and
• a second step wherein the oxidized-state catalyst with the coke deposited thereon is contacted with an oxygen-containing gas insufficient for achieving comp1ete combustion of the coke, at a temperature of from 750.degree. to 950.degree. C., to partially combust the coke on the catalyst, to convert the oxidized-state catalyst into a reduced-state catalyst, and to fix a sulfur compound contained in the coke as iron sulfide with a part of the reduced-state catalyst, wherein the improvement comprises that:
• (1) a major portion of the catalyst is recycled between the first step and second step;
• and
• (2) there is provided a third step wherein a part of the catalyst with coke deposited thereon formed in the first step is contacted with an oxygen-containing gas at a temperature of from 600.degree. to 1,000.degree. C. to effect roasting and gasification of iron sulfide in the catalyst, the catalyst after roasting and gasification of iron sulfide being recycled to the first step or the second step, or to both the first and second steps.