Catalyst demetallization with a reductive SO2 wash

Claim 2

In a process for treating a metal poisoned-containing catalyst which has been poisoned in a hydrocarbon conversion process, wherein a feedstock containing at least one of said metals is contacted with catalyst to convert hydrocarbon and deposit carbonaceous material is removed from said catalyst, the improvement which comprises: (i) contacting said metal poison-containing catalyst with at least one sulfiding agent to convert at least a portion of said poison metal to metal-sulfur-containing compound and form a sulfided catalyst; (ii) contacting said sulfided catalyst with an oxygen-containing medium at conditions to promote subsequent metals removal and form a promoted catalyst; (iii) contacting said promoted catalyst with an aqueous, SO 2 reductive wash medium to remove at least a portion of the metal poison from said promoted catalyst, said contacting being effected in a contact time of about 0.5-15 minutes; (iv) subjecting said reductively washed catalyst to an aqueous oxidative wash; and (v) recovering a catalyst of reduced metal poison content and improved catalytic activity.

Claim 3

A process as in claim 1 wherein the reductive wash medium is a saturated SO 2 solution.

Claim 4

The process as in claim 1 wherein said reductive wash is effect at a temperature of about 65°-80° C.

Claim 5

A process as in claim 3 where said contact time is about 1-5 minutes.

Claim 6

A process as in claim 1 wherein the oxidative wash medium is an aqueous solution of hydrogen peroxide.

Claim 7

A process as in claim 5 wherein said oxidative wash is effected at a temperature of about 60°-85° C. with a contact time of about 1-5 minutes.

Claim 8

A process as in claim 6 wherein said aqueous hydrogen peroxide comprises about 2 to 30 weight % hydrogen peroxide.

Claim 9

A process as in claim 1 which comprises alternating reductive and oxidative washes, the last wash comprising an oxidative wash.

Claim 10

A process as in claim 1 wherein the contaminated catalyst comprises a zeolitic molecular sieve.

Claim 11

A process as in claim 9 wherein said zeolitic molecular sieve comprises a decationized zeolitic molecular sieve having less than 90% of the aluminum atoms associated with cations, a crystalline structure capable of internally absorbing benzene and a SiO 2 to Al 2 O 3 molar ratio greater than 3.

Claim 12

A process as in claim 1 wherein said reductively washed catalyst is washed to remove at least a portion of the SO 2 prior to the oxidative wash.

Claim 13

In a catalytic cracking process wherein a hydrocarbon feedstock contaminated with at least one metal is contacted with catalyst in a cracking reaction zone to convert at least a portion of said feedstock to mroe valuable, lower boiling hydrocarbon products and to deposit carbonaceous material on said catalyst and form a metal poisoned-containing catalyst and at least a portion of said carbonaceous material is removed from said catalyst, the improvement which comprises: (i) withdrawing at least a portion of said metal poisoned-containing catalyst from said cracking reaction zone; (ii) contacting said metal poisoned-containing catalyst with at least one sulfiding agent to convert at least a portion of said poison metal to metal-sulfur-containing compound and form a sulfided catalyst; (iii) contacting said sulfided catalyst with an oxygen-containing medium at conditions to promote subsequent metals removal and form a promoted catalyst; (iv) contacting said promoted catalyst with an aqueous, SO 2 reductive wash medium to remove at least a portion of the metal poison from said promoted catalyst, said contacting being effected in a contact time of about 0.5-15 minutes; (v) subjecting said redutively washed catalyst to an aqueous oxidative wash; (vi) recovering a catalyst of reduced metal poison content and improved catalytic activity; and (vii) returning at least a portion of said recovered catalyst to said cracking reaction zone.

Claim 14

In a catalytic cracking process wherein a hydrocarbon feedstock contaminated with at least one metal is contacted with catalyst in a cracking reaction zone to convert at least a portion of said feedstock to mroe valuable, lower boiling hydrocarbon products and to deposit carbonaceous material on said catalyst and form a metal poisoned-containing catalyst and at least a portion of said carbonaceous material is removed from said catalyst, the improvement which comprises: (i) withdrawing at least a portion of said metal poisoned-containing catalyst from said cracking reaction zone; (ii) contacting said metal poisoned-containing catalyst with at least one sulfiding agent to convert at least a portion of said poison metal to metal-sulfur-containing compound and form a sulfided catalyst; (iii) contacting said sulfided catalyst with an oxygen-containing medium at conditions to promote subsequent metals removal and form a promoted catalyst; (iv) contacting said promoted catalyst with an aqueous, SO 2 reductive wash medium to remove at least a portion of the metal poison from said promoted catalyst, said contacting being effected in a contact time of about 0.5-15 minutes; (v) subjecting said redutively washed catalyst to an aqueous oxidative wash; (vi) recovering a catalyst of reduced metal poison content and improved catalytic activity; and (vii) returning at least a portion of said recovered catalyst to said cracking reaction zone.

Claim 15

A process as in claim 12 wherein the reductive aqueous wash medium is a solution of SO 2 in water.

Claim 16

A process as in claim 12 wherein reductive wash medium is a saturated SO 2 solution.

Claim 17

A process as in claim 14 wherein said reductive wash is effected at a temperature of about 65°-80° C. with a contact time of about 0.5-10 minutes.

Claim 18

A process as in claim 15 where said contact time is about 1-5 minutes.

Claim 19

A process as in claim 12 wherein the oxidative wash medium is an aqueous solution of hydrogen peroxide.

Claim 20

A process as in claim 17 wherein said oxidative wash is effected at a temperature of about 60°-85° C. with a contact time of about 1-5 minutes.

Claim 21

A process as in claim 18 wherein said aqueous hydrogen peroxide comprises about 2 to 30 weight % hydrogen peroxide.

Claim 22

A process as in claim 12 which comprises alternate reductive and oxidative wahses, the last wash comprising an oxidative wash.

Claim 23

A process as in claim 12 wherein the contaminated catalyst comprises a zeolitic molecular sieve.

Claim 24

A process as in claim 12 wherein said zeolite molecular sieve comprises a decationized zeolitic molecular sieve having less than 90% of the aluminum atoms associated with cations, a crystalline structure capable of internally absorbing benzene and a SiO 2 to Al 2 O 3 molar ratio greater than 3.

Claim 25

A process as in claim 12 wherein said reductively washed catalyst is washed to remove at least a portion of the SO 2 prior to the oxidative wash.

Claim 26

A process as in claim 12 where said feedstock is a reduced or topped crude.