Carbo-metallic oil conversion with controlled co:co.sub.2 ratio in

Abstract

A process is disclosed for cracking a carbo-metallic oil feed containing 650.degree. F. material which is characterized by a carbon residue on pyrolysis of at least about 1 and by a level of heavy metal(s) of at least about 4.0 ppm by weight of Nickel Equivalents. The process includes contacting the feed with cracking catalyst bearing an accumulation of substantially more than 600 ppm by weight of Nickel Equivalents of heavy metal(s). The resultant stream flows through a progressive flow type reactor for a vapor residence time of about 0.5 to about 10 seconds at conditions sufficient for causing a conversion per pass of about 50% to about 90% while producing coke in amounts of at least about 6% by weight based on fresh feed and laying down coke on the catalyst in amounts of at least about 0.3% by weight based on catalyst. After such contact, catalyst is separated from product vapors, stripped, and thereafter regenerated in at least a first regeneration zone and a second regeneration zone separate from the first regeneration zone. The amount of oxygen-containing gas in the first regeneration zone is sufficient to convert a major portion of the coke on the catalyst to carbon oxides. The amount of oxygen-containing gas in the second regeneration zone is sufficient to reduce the weight of residual coke on the catalyst to about 0.25% or less. The total amount of oxygen-containing gas supplied to all regeneration zones is less than the stoichiometric amount which would be required to burn all of the carbon in the coke to CO.sub.2, to burn all of the hydrogen in the coke to water, and to burn any other combustibles which may be present in the coke to their respective combustion products. After such regeneration, the regenerated catalyst is recycled to the reactor for contact with fresh feed.