Use of naphtha as riser diluent in carbo-metallic oil conversion

A process for converting carbo-metallic oils to lighter products, comprising:

• (a) providing a converter feed containing 650.degree. F.+ material, said 650.degree. F.+ material being characterized by a carbon residue on pryolysis of at least about 1 and by containing at least about 4 ppm of Nickel Equivalents of heavy metals(s);
• (b) bringing said converter feed together with naphtha;
• (c) bringing said converter feed and said naphtha together with a high-metal content cracking catalyst;
• (d) forming a stream containing said converter feed, said naphtha and said catalyst and causing said stream to flow through a progressive flow type reactor having an elongated reaction chamber which is at least in part vertical or inclined for a predetermined vapor residence time in the range of about 0.5 to about 10 seconds at a temperature of about 900.degree. F. to about 1400.degree. F. and under a pressure of about 10 to about 50 pounds per square inch absolute sufficient for causing a conversion per pass in the range of about 50% to about 90% while producing coke in amounts in the range of about 5% to about 14% by weight based on fresh feed, and laying down coke on the catalyst in amounts in the range of about 0.3% to about 3% by weight;
• (e) separating said catalyst from the resultant cracking products;
• (f) stripping hydrocarbons from said separated catalyst;
• (g) regenerating said catalyst with oxygen-containing combustion-supporting gas under conditions of time, temperature and atmosphere sufficient to reduce the carbon on said catalyst to about 0.25% by weight or less, while forming a gaseous combustion product comprising CO and/or CO.sub.2 ;
• and
• (h) recycling the regenerated catalyst to the reactor for contact with fresh converter feed.