US4148751A
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US
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Method of regenerating coke-contaminated catalyst with simultaneous combustion of carbon monoxide
Assignee: Honeywell UOP LLC
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Filing: 1976-06-17
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Granted: 1979-04-10
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Expires: 1996-06-17
Abstract
Abstract A method for regenerating a coke-contaminated cracking catalyst with the simultaneous carefully controlled catalyzed combustion of CO to CO2 within a regeneration zone to produce regenerated catalyst and flue gas. Novel features of the method include adding to the regeneration zone, independently of the cracking catalyst, a supported CO oxidation promoter and combusting CO to CO2 in the presence of the promoter and regenerated catalyst. A supported oxidation promoter may be added to the regeneration zone in amounts to control the CO concentration in the flue gas, a regeneration zone temperature, or the residual carbon concentration on regenerated catalyst.
Inventors
- 👤 Charles L. Hemler, Jr.
- 👤 Laurence O. Stine
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 20:25
CPC Classifications
B; B01; B01J; B01J38/00; B01J38/04; B01J38/12; B01J38/30; B01J38/36; B01J23/00; B01J23/90; B01J23/96; C; C10; C10G; C10G11/00; C10G11/14; C10G11/18; C10G11/182; Y; Y02; Y02P; Y02P30/00; Y02P30/40
Claims Analysis
Total Claims: 33
Claim 1
Independent Claim
334 words
A method for regenerating a coke-contaminated hydrocarbon conversion catalyst with simultaneous carefully-controlled combustion of CO which comprises the steps of: (a) passing said coke-contaminated catalyst containing from about 0.2 to about 1.5 wt. % coke from a hydrocarbon conversion zone into a regeneration zone; (b) adding to the regeneration zone, independently of said coke-contaminated hydrocarbon conversion catalyst and free of reactor feed stock in an amount selected to promote the combustion of CO to CO 2 , a CO oxidation promoter consisting essentially of about 0.001 wt. % to about 10.000 wt. % platinum supported on alumina possessing a particle size of from about 1 micron to about 200 microns, said promoter being present in an amount of from about 0.1 to about 25 wt. ppm of the circulating catalyst inventory calculated on an elemental metal basis; (c) passing oxygen-containing regeneration gas into said regeneration zone in an amount selected to burn said coke from said coke-contaminated hydrocarbon conversion catalyst and to provide sufficient excess oxygen to accomplish the desired amount of CO combustion; (d) reacting a first portion of the oxygen-containing regeneration gas with said coke-contaminated hydrocarbon conversion catalyst in said regeneration zone at oxidation conditions which are selected to remove said coke from said coke-contaminated hydrocarbon conversion catalyst and to produce a flue gas containing CO and which are sufficient to cause combustion of CO to CO 2 in the presence of said independently added oxidation promoter; (e) simultaneously contacting said flue gas and a second portion of the oxygen-containing regeneration gas with said CO oxidation promoter in said regeneration zone in the presence of regenerated catalyst at said oxidation conditions, thereby (i) making a controlled quantity of exothermic heat of reaction available for operation of said regeneration zone and (ii) decreasing the amount of CO in flue gas to less than 1000 ppm; and, (f) passing said platinum-alumina CO-promoter in admixture with said regenerated catalyst from said regeneration zone to the hydrocarbon reaction zone and back again to said regeneration zone.
Claim 2
Independent Claim
334 words
A method for regenerating a coke-contaminated hydrocarbon conversion catalyst with simultaneous carefully-controlled combustion of CO which comprises the steps of: (a) passing said coke-contaminated catalyst containing from about 0.2 to about 1.5 wt. % coke from a hydrocarbon conversion zone into a regeneration zone; (b) adding to the regeneration zone, independently of said coke-contaminated hydrocarbon conversion catalyst and free of reactor feed stock in an amount selected to promote the combustion of CO to CO 2 , a CO oxidation promoter consisting essentially of about 0.001 wt. % to about 10.000 wt. % platinum supported on alumina possessing a particle size of from about 1 micron to about 200 microns, said promoter being present in an amount of from about 0.1 to about 25 wt. ppm of the circulating catalyst inventory calculated on an elemental metal basis; (c) passing oxygen-containing regeneration gas into said regeneration zone in an amount selected to burn said coke from said coke-contaminated hydrocarbon conversion catalyst and to provide sufficient excess oxygen to accomplish the desired amount of CO combustion; (d) reacting a first portion of the oxygen-containing regeneration gas with said coke-contaminated hydrocarbon conversion catalyst in said regeneration zone at oxidation conditions which are selected to remove said coke from said coke-contaminated hydrocarbon conversion catalyst and to produce a flue gas containing CO and which are sufficient to cause combustion of CO to CO 2 in the presence of said independently added oxidation promoter; (e) simultaneously contacting said flue gas and a second portion of the oxygen-containing regeneration gas with said CO oxidation promoter in said regeneration zone in the presence of regenerated catalyst at said oxidation conditions, thereby (i) making a controlled quantity of exothermic heat of reaction available for operation of said regeneration zone and (ii) decreasing the amount of CO in flue gas to less than 1000 ppm; and, (f) passing said platinum-alumina CO-promoter in admixture with said regenerated catalyst from said regeneration zone to the hydrocarbon reaction zone and back again to said regeneration zone.
Claim 3
Dependent Claim
36 words
A method as defined in claim 1 wherein the amount of platinum supported CO oxidation promoter added to said regeneration zone is selected to produce flue gas containing CO in an amount less than 500 ppm.
Claim 4
Dependent Claim
70 words
A method as defined in claim 1 wherein the amount of platinum supported on alumina CO oxidation promoter added to said regeneration zone in step (b) is selected to release an amount of exothermic heat of reaction sufficient to raise the average combustion temperature in said zone to a level effective to produce a regenerated catalyst containing residual carbon in an amount less than or equal to a predetermined value.
Claim 5
Dependent Claim
50 words
A method as defined in claim 1 wherein the amount of platinum supported on alumina CO oxidation promoter added to said regeneration zone in step (b) is selected to release an amount of exothermic heat of reaction sufficient to raise the temperature of the regenerated catalyst to a predetermined level.
Claim 6
Dependent Claim
69 words
A method as defined in claim 1 wherein the amount of platinum supported on alumina CO oxidation promoter added to said regeneration zone in step (b) is adjusted to a value sufficient to insure that substantially all of the heat released from the exothermic combustion of carbon monoxide occurs in the presence of regenerated catalyst thereby enabling control of the temperature of the flue gas below a predetermined level.
Claim 7
Dependent Claim
55 words
A method as defined in claim 1 wherein the amount of platinum supported on alumina CO oxidation promoter added to said regeneration zone in step (b) is adjusted in conjunction with an amount of diluent gas passed to said zone to enable control of the temperature of the flue gas effluent below a predetermined level.
Claim 8
Dependent Claim
295 words
In a process for catalytically cracking a hydrocarbon feed stream wherein coke-contaminated cracking catalyst containing from about 0.2 to about 1.5 wt. % coke from a hydrocarbon conversion zone and oxygen containing regeneration gas are passed to a regeneration zone maintained at coke oxidizing conditions wherein said coke is oxidized to produce a regenerated catalyst and a flue gas containing carbon dioxide and carbon monoxide, a method of using the in situ combustion of CO to CO 2 to control the operation of the regeneration zone which comprises the steps of: (a) passing to said regeneration zone, independently of said coke-contaminated cracking catalyst and free of reactor feed stock in an amount selected to initiate and sustain the combustion of CO to CO 2 in said zone in the presence of regenerated catalyst, a CO oxidation promoter consisting essentially of from 0.001 wt. % to about 10.000 wt. % platinum supported on alumina possessing a particle size of from about 1 micron to about 200 microns, said promoter being present in an amount of from about 0.1 to about 25 wt. ppm of the circulating catalyst inventory calculated on an elemental metal basis; (b) thereafter adjusting the amount of oxygen-containing regeneration gas being passed to said zone to a value stoichiometrically sufficient to burn said coke from the catalyst and to convert at least a portion of the CO to CO 2 , thereby (i) making a controlled quantity of exothermic heat of reaction available for operation of said regeneration zone and (ii) decreasing the amount of CO in the flue gas to less than 1000 ppm; and, (c) passing said platinum-alumina CO-promoter in admixture with said regenerated catalyst from said regeneration zone to the hydrocarbon reaction zone and back again to said regeneration zone.
Claim 9
Dependent Claim
295 words
In a process for catalytically cracking a hydrocarbon feed stream wherein coke-contaminated cracking catalyst containing from about 0.2 to about 1.5 wt. % coke from a hydrocarbon conversion zone and oxygen containing regeneration gas are passed to a regeneration zone maintained at coke oxidizing conditions wherein said coke is oxidized to produce a regenerated catalyst and a flue gas containing carbon dioxide and carbon monoxide, a method of using the in situ combustion of CO to CO 2 to control the operation of the regeneration zone which comprises the steps of: (a) passing to said regeneration zone, independently of said coke-contaminated cracking catalyst and free of reactor feed stock in an amount selected to initiate and sustain the combustion of CO to CO 2 in said zone in the presence of regenerated catalyst, a CO oxidation promoter consisting essentially of from 0.001 wt. % to about 10.000 wt. % platinum supported on alumina possessing a particle size of from about 1 micron to about 200 microns, said promoter being present in an amount of from about 0.1 to about 25 wt. ppm of the circulating catalyst inventory calculated on an elemental metal basis; (b) thereafter adjusting the amount of oxygen-containing regeneration gas being passed to said zone to a value stoichiometrically sufficient to burn said coke from the catalyst and to convert at least a portion of the CO to CO 2 , thereby (i) making a controlled quantity of exothermic heat of reaction available for operation of said regeneration zone and (ii) decreasing the amount of CO in the flue gas to less than 1000 ppm; and, (c) passing said platinum-alumina CO-promoter in admixture with said regenerated catalyst from said regeneration zone to the hydrocarbon reaction zone and back again to said regeneration zone.
Claim 10
Dependent Claim
38 words
A method as defined in claim 2 wherein the amount of platinum supported on alumina CO oxidation promoter added to said regeneration zone is selected to produce flue gas containing CO in an amount less than 500 ppm.
Claim 11
Dependent Claim
69 words
A method defined in claim 7 wherein the amount of platinum supported on alumina CO oxidation promoter added to said regeneration zone in step (a) is selected to release an amount of exothermic heat of reaction sufficient to raise the average combustion temperature in said zone to a level effective to produce a regenerated catalyst containing residual carbon in an amount less than or equal to a predetermined value.
Claim 12
Dependent Claim
49 words
A method as defined in claim 7 wherein the amount of platinum supported on alumina CO oxidation promoter added to said regeneration zone in step (a) is selected to release an amount of exothermic heat of reaction to raise the temperature of the regenerated catalyst to a predetermined level.
Claim 13
Dependent Claim
68 words
A method as defined in claim 7 wherein the amount of platinum supported on alumina CO oxidation promoter added to the zone in step (a) is adjusted to a value sufficient to insure that substantially all of the heat released from the exothermic combustion of carbon monoxide occurs in the presence of regenerated catalyst thereby enabling control of the temperature of the flue gas below a predetermined level.
Claim 14
Dependent Claim
50 words
A method as defined in claim 8 wherein the amount of platinum supported on alumina CO oxidation promoter added in step (a) is adjusted in conjunction with an amount of diluent gas passed to said zone to enable control of the temperature of the flue gas below a predetermined level.
Claim 15
Dependent Claim
316 words
In a process for catalytically cracking a hydrocarbon feed stream wherein coke-contaminated cracking catalyst containing from about 0.2 to about 1.5 wt. % coke from a hydrocarbon conversion zone and oxygen-containing regeneration gas are passed to a regeneration zone maintained at oxidizing conditions and said coke is therein oxidized to produce regenerated catalyst and flue gas containing CO 2 and CO, a method of controlling the CO concentration in the flue gas within a predetermined CO concentration range which method comprises the steps of: (a) passing to said regeneration zone, independently of said coke-contaminated catalyst and free of reactor feed stock in an amount selected to promote the combustion of CO to CO 2 , a CO oxidation promoter consisting essentially of about 0.001 wt. % to about 10.000 wt. % platinum supported on alumina possessing a particle size of from about 1 micron to about 200 microns, said promoter being present in an amount of from about 0.1 to about 25 wt. ppm of the circulating catalyst inventory calculated on an elemental metal basis; (b) passing to said regeneration zone oxygen-containing regeneration gas in an amount stoichiometrically sufficient to convert at least a portion of the CO to CO 2 ; (c) converting in said regeneration zone, at conversion conditions including the presence of said CO oxidation promoter and regenerated catalyst, at least a portion of the CO to CO 2 to produce flue gas containing CO 2 and CO; (d) analyzing said flue gas to determine a measured CO concentration and comparing said measured CO concentration with said predetermined CO concentration range; (e) passing to said regeneration zone said CO oxidation promoter in amounts to maintain said measured CO concentration within said predetermined CO concentration range; and, (f) passing said platinum-alumina CO-promoter in admixture with said regenerated catalyst from said regeneration zone to the hydrocarbon reaction zone and back again to said regeneration zone.
Claim 16
Dependent Claim
316 words
In a process for catalytically cracking a hydrocarbon feed stream wherein coke-contaminated cracking catalyst containing from about 0.2 to about 1.5 wt. % coke from a hydrocarbon conversion zone and oxygen-containing regeneration gas are passed to a regeneration zone maintained at oxidizing conditions and said coke is therein oxidized to produce regenerated catalyst and flue gas containing CO 2 and CO, a method of controlling the CO concentration in the flue gas within a predetermined CO concentration range which method comprises the steps of: (a) passing to said regeneration zone, independently of said coke-contaminated catalyst and free of reactor feed stock in an amount selected to promote the combustion of CO to CO 2 , a CO oxidation promoter consisting essentially of about 0.001 wt. % to about 10.000 wt. % platinum supported on alumina possessing a particle size of from about 1 micron to about 200 microns, said promoter being present in an amount of from about 0.1 to about 25 wt. ppm of the circulating catalyst inventory calculated on an elemental metal basis; (b) passing to said regeneration zone oxygen-containing regeneration gas in an amount stoichiometrically sufficient to convert at least a portion of the CO to CO 2 ; (c) converting in said regeneration zone, at conversion conditions including the presence of said CO oxidation promoter and regenerated catalyst, at least a portion of the CO to CO 2 to produce flue gas containing CO 2 and CO; (d) analyzing said flue gas to determine a measured CO concentration and comparing said measured CO concentration with said predetermined CO concentration range; (e) passing to said regeneration zone said CO oxidation promoter in amounts to maintain said measured CO concentration within said predetermined CO concentration range; and, (f) passing said platinum-alumina CO-promoter in admixture with said regenerated catalyst from said regeneration zone to the hydrocarbon reaction zone and back again to said regeneration zone.
Claim 17
Dependent Claim
51 words
A method as described in claim 13 wherein the amount of platinum supported on alumina oxidation promoter passed into said regeneration zone in step (a) is sufficient to provide a promoter concentration of from about 0.1 to about 15 wt. ppm. of the circulating catalyst inventory on an elemental metal basis.
Claim 18
Dependent Claim
36 words
A method as described in claim 13 wherein the amount of oxygen-containing regeneration gas is equivalent to about 10 to about 17 pounds of air per pound of coke entering the regeneration zone per unit time.
Claim 19
Dependent Claim
33 words
A method as described in claim 13 wherein said conversion conditions include a temperature of from about 1100° F. to about 1450° F. and a pressure of from about atmospheric to 50 psig.
Claim 20
Dependent Claim
50 words
A method as described in claim 13 wherein the amount of platinum on alumina oxidation promoter passed into said regeneration zone in step (e) is sufficient to provide a promoter concentration of from about 0.005 to about 10 wt. ppm of the circulating catalyst inventory on an elemental metal basis.
Claim 21
Dependent Claim
313 words
In a process for catalytically cracking a hydrocarbon feed stream wherein coke-contaminated cracking catalyst containing from about 0.2 to about 1.5 wt. % coke from a hydrocarbon conversion zone and oxygen-containing regeneration gas are passed to a regeneration zone maintained at oxidizing conditions and said coke is therein oxidized to produce regenerated catalyst and flue gas containing CO 2 and CO, a method of controlling a regeneration zone temperature within a predetermined temperature range which method comprises the steps of: (a) passing to said regeneration zone, independently of said coke-contaminated catalyst and free of reactor feed stock in an amount selected to promote the combustion of CO to CO 2 , a CO oxidation promoter consisting essentially of about 0.001 wt. % to about 10.000 wt. % platinum supported on alumina possessing a particle size of from about 1 micron to about 200 microns, said promoter being present in an amount of from about 0.1 to about 25 wt. ppm of the circulating catalyst inventory calculated on an elemental metal basis; (b) passing to said regeneration zone oxygen-containing regeneration gas in an amount stoichiometrically sufficient to convert at least a portion of the CO to CO 2 ; (c) converting in said regeneration zone, at conversion conditions including the presence of said CO oxidation promoter and regenerated catalyst, at least a portion of the CO to CO 2 to produce flue gas containing CO 2 and CO; (d) measuring a regeneration zone temperature to determine a measured regeneration zone temperature and comparing said measured concentration with said predetermined temperature range; (e) passing to said regeneration zone said platinum-alumina CO oxidation promoter in amounts to maintain said measured regeneration zone temperature within said predetermined temperature range; and, (f) passing said platinum-alumina CO-promoter in admixture with said regenerated catalyst from said regeneration zone to the hydrocarbon reaction zone and back again to said regeneration zone.
Claim 22
Dependent Claim
313 words
In a process for catalytically cracking a hydrocarbon feed stream wherein coke-contaminated cracking catalyst containing from about 0.2 to about 1.5 wt. % coke from a hydrocarbon conversion zone and oxygen-containing regeneration gas are passed to a regeneration zone maintained at oxidizing conditions and said coke is therein oxidized to produce regenerated catalyst and flue gas containing CO 2 and CO, a method of controlling a regeneration zone temperature within a predetermined temperature range which method comprises the steps of: (a) passing to said regeneration zone, independently of said coke-contaminated catalyst and free of reactor feed stock in an amount selected to promote the combustion of CO to CO 2 , a CO oxidation promoter consisting essentially of about 0.001 wt. % to about 10.000 wt. % platinum supported on alumina possessing a particle size of from about 1 micron to about 200 microns, said promoter being present in an amount of from about 0.1 to about 25 wt. ppm of the circulating catalyst inventory calculated on an elemental metal basis; (b) passing to said regeneration zone oxygen-containing regeneration gas in an amount stoichiometrically sufficient to convert at least a portion of the CO to CO 2 ; (c) converting in said regeneration zone, at conversion conditions including the presence of said CO oxidation promoter and regenerated catalyst, at least a portion of the CO to CO 2 to produce flue gas containing CO 2 and CO; (d) measuring a regeneration zone temperature to determine a measured regeneration zone temperature and comparing said measured concentration with said predetermined temperature range; (e) passing to said regeneration zone said platinum-alumina CO oxidation promoter in amounts to maintain said measured regeneration zone temperature within said predetermined temperature range; and, (f) passing said platinum-alumina CO-promoter in admixture with said regenerated catalyst from said regeneration zone to the hydrocarbon reaction zone and back again to said regeneration zone.
Claim 23
Dependent Claim
51 words
A method as described in claim 18 wherein the amount of platinum supported on alumina oxidation promoter passed into said regeneration zone in step (a) is sufficient to provide a promoter concentration of from about 0.1 to about 15 wt. ppm. of the circulating catalyst inventory on an elemental metal basis.
Claim 24
Dependent Claim
36 words
A method as described in claim 18 wherein the amount of oxygen-containing regeneration gas is equivalent to about 10 to about 17 pounds of air per pound of coke entering the regeneration zone per unit time.
Claim 25
Dependent Claim
34 words
A method as defined in claim 18 wherein said conversion conditions include a temperature of from about 1100° F. to about 1450° F. and a pressure of from about atmospheric pressure to 50 psig.
Claim 26
Dependent Claim
51 words
A method as described in claim 18 wherein the amount of platinum supported on alumina oxidation promoter passed into said regeneration zone in step (e) is sufficient to provide a promoter concentration of from about 0.005 to about 10 wt. ppm. of the circulating catalyst inventory on an elemental metal basis.
Claim 27
Dependent Claim
16 words
A method as defined in claim 18 wherein said regeneration zone temperature is a dilute-phase temperature.
Claim 28
Dependent Claim
323 words
In a process for catalytically cracking a hydrocarbon feed stream wherein coke-contaminated cracking catalyst containing from about 0.2 to about 1.5 wt. % coke from a hydrocarbon conversion zone and oxygen-containing regeneration gas are passed to a regeneration zone maintained at oxidizing conditions and said coke is therein oxidized to produce regenerated catalyst and flue gas containing CO 2 and CO, a method of controlling the concentration of residual carbon on regenerated catalyst within a predetermined residual carbon concentration range which method comprises the steps of: (a) passing to said regeneration zone, independently of said coke-contaminated catalyst and free of reactor feed stock in an amount selected to promote the combustion of CO to CO 2 , a CO oxidation promoter consisting essentially of about 0.001 wt. % to about 10.000 wt. % platinum supported on alumina possessing a particle size of from about 1 micron to about 200 microns, said promoter being present in an amount of from about 0.1 to about 25 wt. ppm of the circulating catalyst inventory calculated on an elemental metal basis; (b) passing to said regeneration zone oxygen-containing regeneration gas in an amount stoichiometrically sufficient to convert at least a portion of the CO to CO 2 ; (c) converting in said regeneration zone, at conversion conditions including the presence of said CO oxidation promoter and regenerated catalyst, at least a portion of the CO to CO 2 to produce flue gas containing CO 2 and CO; (d) analyzing regenerated catalyst to determine a measured residual carbon concentration and comparing said measured residual carbon concentration with said predetermined residual carbon concentration range; (e) passing to said regeneration zone said platinum-alumina CO oxidation promoter in amounts to maintain said measured residual carbon concentration within said predetermined residual carbon concentration range; and, (f) passing said platinum-alumina CO-promoter in admixture with said regenerated catalyst from said regeneration zone to the hydrocarbon reaction zone and back again to said regeneration zone.
Claim 29
Dependent Claim
323 words
In a process for catalytically cracking a hydrocarbon feed stream wherein coke-contaminated cracking catalyst containing from about 0.2 to about 1.5 wt. % coke from a hydrocarbon conversion zone and oxygen-containing regeneration gas are passed to a regeneration zone maintained at oxidizing conditions and said coke is therein oxidized to produce regenerated catalyst and flue gas containing CO 2 and CO, a method of controlling the concentration of residual carbon on regenerated catalyst within a predetermined residual carbon concentration range which method comprises the steps of: (a) passing to said regeneration zone, independently of said coke-contaminated catalyst and free of reactor feed stock in an amount selected to promote the combustion of CO to CO 2 , a CO oxidation promoter consisting essentially of about 0.001 wt. % to about 10.000 wt. % platinum supported on alumina possessing a particle size of from about 1 micron to about 200 microns, said promoter being present in an amount of from about 0.1 to about 25 wt. ppm of the circulating catalyst inventory calculated on an elemental metal basis; (b) passing to said regeneration zone oxygen-containing regeneration gas in an amount stoichiometrically sufficient to convert at least a portion of the CO to CO 2 ; (c) converting in said regeneration zone, at conversion conditions including the presence of said CO oxidation promoter and regenerated catalyst, at least a portion of the CO to CO 2 to produce flue gas containing CO 2 and CO; (d) analyzing regenerated catalyst to determine a measured residual carbon concentration and comparing said measured residual carbon concentration with said predetermined residual carbon concentration range; (e) passing to said regeneration zone said platinum-alumina CO oxidation promoter in amounts to maintain said measured residual carbon concentration within said predetermined residual carbon concentration range; and, (f) passing said platinum-alumina CO-promoter in admixture with said regenerated catalyst from said regeneration zone to the hydrocarbon reaction zone and back again to said regeneration zone.
Claim 30
Dependent Claim
49 words
A method as described in claim 24 wherein the amount of platinum supported oxidation promoter passed into said regeneration zone in step (a) is sufficient to provide a promoter concentration of from about 0.1 to about 15 wt. ppm. of the circulating catalyst inventory on an elemental metal basis.
Claim 31
Dependent Claim
36 words
A method as described in claim 24 wherein the amount of oxygen-containing regeneration gas is equivalent to about 10 to about 17 pounds of air per pound of coke entering the regeneration zone per unit time.
Claim 32
Dependent Claim
34 words
A method as described in claim 24 wherein said conversion conditions include a temperature of from about 1100° F. to about 1450° F. and a pressure of from about atmospheric pressure to 50 psig.
Claim 33
Dependent Claim
51 words
A method as described in claim 24 wherein the amount of platinum supported on alumina oxidation promoter passed into said regeneration zone in step (e) is sufficient to provide a promoter concentration of from about 0.005 to about 10 wt. ppm. of the circulating catalyst inventory on an elemental metal basis.
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USPTO Annuity & Maintenance Windows
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| 3.5 Years (Year 4) | 1982-04-09 | 1982-10-09 | 1983-04-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-04-09 | 1986-10-09 | 1987-04-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-04-09 | 1990-10-09 | 1991-04-10 | $7700.00 | Window Closed / Lapsed |