Process for cracking hydrocarbon oils

A process for cracking hydrocarbon oils comprising:

• contacting a hydrocarbon oil with a catalyst in a reactor having a first reaction zone, and a second reaction zone which is after the first reaction zone, under cracking reaction conditions;
• separating the reaction products and the catalyst to obtain spent catalyst;
• regenerating at least a part of the spent catalyst;
• contacting at least a part of the regenerated catalyst and/or a fresh catalyst with an atmosphere containing a reducing gas, after contacting with the reducing gas the reduced catalyst is recirculated to one reaction zone of the first reaction zone or the second reaction zone and contacted with hydrocarbon oil;
• and
• recirculating the spent catalyst which is not regenerated, the regenerated catalyst which is not reduced, or the catalyst which was subject to the above reduction procedure, to another reaction zone of the first reaction zone or the second reaction zone to contact hydrocarbon oil and react;
• wherein said catalyst is a cracking catalyst containing a metal component, or a catalyst mixture of a cracking catalyst containing a metal component and a cracking catalyst free of metal component, the content of the metal component is 0.1-30 wt % based on said cracking catalyst containing metal component and calculated according to the oxide of the metal component being in the maximum oxidation state;
• said metal component is one or more metals selected from the group consisting of:
• non-aluminum metals of Group IIIA, metals of Group IVA, Group VA, Group IB, Group IIB, Group VB, Group VIB, Group VIIB, non-noble metals of Group VIII, and rare-earth metals;
• and
• the catalyst is contacted with the atmosphere containing a reducing gas at a temperature of 100-900° C. and a pressure 0.1-0.5 MPa held for at least 1 second, and the amount of the atmosphere containing a reducing gas is no less than 0.03 cubic meters of reducing gas per ton of cracking catalyst containing metal component per minute.