Metals passivation by magnetic treatment to permit higher metals levels on FCC catalyst

A process for the fluidized catalytic cracking (FCC) of a metals-contaminated hydrocarbon feed to lighter products comprising:

• a) mixing a crackable hydrocarbon feed containing at least one of nickel, iron, vanadium and compounds and combinations thereof with a source of hot regenerated catalyst in a cracking reaction zone of an FCC unit to produce a mixture of cracked products and spent catalyst containing coke and nickel, iron, vanadium or a combination thereof deposited on the catalyst during the cracking reaction;
• b) separating the spent catalyst from the cracked products;
• c) removing the cracked products from the process;
• d) stripping spent catalyst in a catalyst stripping zone by contact with stripping vapor to remove strippable hydrocarbons from the spent catalyst and produce stripped catalyst containing coke and nickel, iron, vanadium or a combination thereof;
• e) regenerating the stripped catalyst in a catalyst regenerator at catalyst regeneration conditions by contact with oxygen or an oxygen-containing gas at a temperature of 1000.degree.-1500.degree. F. in a fluidized bed to produce regenerated metals-contaminated catalyst containing an initial level of metals for recycle to the cracking reaction zone;
• f) continuously removing catalyst from the FCC process to produce a flowing slipstream of metals-contaminated catalyst;
• g) magnetizing or magnetically conditioning the metals-contaminated catalyst by passage through a magnetic field of sufficient strength to at least temporarily magnetize the metal-contaminated catalyst and produce conditioned catalyst;
• h) magnetically and inertially separating the conditioned catalyst into a relatively high metal fraction which is discarded and a magnetized relatively low metal catalyst fraction;
• i) recycling the relatively low metal catalyst fraction to the FCC process;
• j) cracking additional quantities of nickel-, iron- or vanadium-contaminated feed with the magnetized low metal catalyst and depositing additional amounts of metals on the conditioned catalyst;
• k) increasing the Ni+V level on the conditioned catalyst by at least 25 weight percent as compared to the initial metals level in step (e) without increasing hydrogen yield or coke make, as compared to the FCC process operating at the same conditions prior to use of conditioned catalyst in steps (f) through (j).

In a process for the fluidized catalytic cracking (FCC) in an FCC unit of a hydrocarbon feed containing metals which deposit on a circulating stream of equilibrium catalyst (ECat) used in the FCC process to crack the feed, wherein metals contained in the feed and metals levels on the circulating ECat are insufficient to require either metals passivation by adding conventional metal passivators or catalyst replacement to control metals levels, and wherein catalyst replacement occurs on a daily to weekly basis to maintain catalyst activity rather than control metals content of circulating ECat, the improvement comprising the steps of:

• a) continuously removing a portion of ECat from the unit;
• b) magnetizing or magnetically conditioning the ECat, by passage through a magnetic field of sufficient strength to at least temporarily magnetize the metal-contaminated ECat and produce a conditioned ECat;
• c) recycling the conditioned ECat to the FCC unit;
• d) cracking additional quantities of metal-contaminated feed with the conditioned ECat, wherein the ECat, prior to magnetic conditioning, has a total nickel plus vanadium content below 2000 ppm, magnetic conditioning of ECat continues for at least two months, during which essentially all of the most metal contaminated fraction is recycled to the FCC unit, and wherein after the at least two months of operation magnetic conditioning of ECat continues in a magnetic separation unit operated to reject a metal contaminated fraction no greater than 10 weight percent of total catalyst charged to the magnetic separation unit.