HIGH TEMPERATURE CATALYTIC CRACKING WITH LOW COKE PRODUCING CRYSTALLINE ZEOLITE CATALYSTS

• US 3,849,291 A
• Filed: 10/05/1971
• Issued: 11/19/1974
• Est. Priority Date: 10/05/1971
• Status: Expired due to Term

• Current Assignee: Hartley Owen
• Original Assignee: Hartley Owen
• Inventors: Owen, Hartley
• Primary Examiner(s): Gantz, Delbert E.
• Assistant Examiner(s): Schmitkons, G. E.
• Application Number:
  US05/186,639
• Time in Patent Office: 1,141 Days
• Field of Search: 208/78,80,120,155,164
• US Class Current: 208/78
• CPC Class Codes: B01J 2229/40 Special temperature treatment, i.e. other than just for template removal
• CPC Class Codes: B01J 29/40 of the pentasil type, e.g. types ZSM-5, ZSM-8 or ZSM-11, as exemplified by patent documents US3702886, GB1334243 and US3709979, respectively
• CPC Class Codes: B01J 29/90 Regeneration or reactivation
• CPC Class Codes: B01J 8/26 with two or more fluidised beds, e.g. reactor and regeneration installations
• CPC Class Codes: C10G 11/18 according to the "fluidised-bed" technique
• CPC Class Codes: Y02P 30/40 Ethylene production
• CPC Class Codes: Y10S 208/02 Molecular sieve

Abstract

A method and arrangement of catalyst handling steps is described for practicing a selective high temperature catalytic cracking of hydrocarbons which will take advantage of the low coke producing catalyst of high activity and selectivity.

Claims

1. IN A DUAL RISER HYDROCARBON CONVERSION OPERATION EMPLOYING FLUIDIZABLE CATALYST PARTICLES, THE IMPROVED METHOD OF OPERATION WHICH COMPRISES, REGENERATING A CATALYST MIXTURE COMPRISING A LARGE PORE CRYSTALLINE ZEOLITE OF THE FAUJASITE TYPE IN ADMIXTURE WITH FROM 10 TO ABOUT 90 WEIGHT PERCENT OF A SMALLER PORE CRYSTALLINE ZEOLITE OF THE ZSM-5 TYPE UNDER CONDITIONS TO HEAT THE CATALYST MIXTURE TO AN ELEVATED TEMPERATURE IN THE RANGE OF 1,000*F. UP TO ABOUT 1400*F., PASSING HEATED CATALYSTS TO THE INLET OF A FIRST RISER CONVERSIO ZONE FOR ADMIXTURE WITH GASEOUS MATERIALS SUCH AS DRY GAS AND/OR C5 AND LIGHTER GASEOUS HYDROCARBONS TO FORM A FIRST SUSPENSION THEREWITH, PASSING SAID FIRST SUSPENSION IN ADMIXTURE WITH A FRESH GAS OIL FEED UPWARDLY THROUGH SAID FIRST CONVERSION ZONE UNDER ELEVATED TEMPERATURE CRACKING CONVERSION CONDITIONS OF AT LEAST 1000*F. AND A HYDROCARBON RESIDENCE TIME LESS THAN ABOUT 12 SECONDS TO CYCLONIC SEPARATION OF THE SUSPENSION INTO A HYDROCARNBON PHASE AND A LOW COKE CONTANINIG CATALYST PHASE, RECOVERING THE HYDROCARRBON PHASE AND STRIPPING THE CATALYST PHASE, PASSING STRIPPED CATALSYT MIXTURE OF RELATIVELY LOW COKE LEVEL SEPARATED FROM SAID FIRST CONVERSION ZONE TO THE INLET OF A SECOND RISER CONVERSION ZONE IN COMBINATION WITH AN INCREMENT OF THE FRESHLY REGENERATED CATALYST, FORMING A SECOND SUSPENSION OF CATALYST WITH GASEOUS MATERIALS SUCH AS DRY GAS AND/OR C5 AND LIGHTER GASEOUS HYDROCARBONS FOR PASSAGE UPWARDLY THROUGH SAID SECOND RISER

2. The process of claim 1 wherein an amount of metal oxide which will enhance regeneration of the catalyst by converting carbon monoxide to carbon dioxide is admixed with the zeolite catalyst mixture and particularly the ZSM-5 crystalline component when employed as separate and discrete particles in admixture with particles of the large pore crystalline zeolite.

3. The method of claim 1 wherein catalyst discharged from each conversion zone is dumped into a common fluid bed of catalyst particles undergoing stripping with a stripping gas, a portion of the stripped catalyst is passed to catalyst regeneration and another portion of the stripped catalyst is combined with freshly regenerated catalyst for passage to the inlet of the second conversion zone.

4. The method of claim 1 wherein contaminated catalyst particles recovered From the second conversion zone stripping operation is regenerated in stages with at least one stage being a dense fluid bed regeneration operation.

5. The method of claim 1 wherein regeneration of the catalyst is accomplished in at least one dispersed phase regeneration operation discharging adjacent the upper interface of a dense fluid bed of catalyst being regenerated.

6. In a process for cracking hydrocarbons with crystalline zeolite cracking catalyst and regenerating coke deactivated catalyst wherein a plurality of riser conversion zones are relied upon for processing a first high boiling hydrocarbon feed in one conversion zone and a second high boiling hydrocarbon feed in another conversion zone and wherein catalyst separated from the product of the first conversion zone is passed in admixture with hot regenerated catalyst to the second conversion zone, the improvement which comprises, using as the hydrocarbon conversion catalyst in the combination operation a mixture of a large pore low coke producing crystalline zeolite in combination with from 10 to 90 weight percent of a crystalline zeolite of the ZSM-5 type, forming a suspension of the catalyst mixture with gaseous hydrocarbons selected from the group comprising C3 and lighter dry gases and/or wet gases comprising C5 and lighter hydrocarbons in the inlet portion of each riser conversion zone, converting a first fresh gas oil feed in admixture with said suspension in the first conversion zone under operating conditions of temperature, catalyst/oil ratio and hydrocarbon residence time designed to particularly restrict the deposition of coke on the low coke producing zeolite catalyst, converting a second higher coke producing hydrocarbon feed in admixture with the suspension in the second conversion zone under operating conditions of temperature, catalyst/oil ratio and hydrocarbon residence time designed to particularly deposit coke upon the catalyst during the conversion operation, cyclonically separating the suspension at the outlet of each conversion zone into a hydrocarbon phase and a catalyst phase, recovering the separated hydrocarbon phase, and passing catalyst separated from the second conversion zone to a catalyst regeneration zone.

7. The method of claim 6 wherein the amount of regenerated catalyst combined with the catalyst separated from the first conversion zone is sufficient to provide a catalyst mixture having a temperature selected from within the range of 950*F. up to about 1,100*F.

8. The method of claim 6 wherein a greater catalyst to oil ratio is employed in the second conversion zone than employed in the first conversion zone.

9. The method of claim 6 wherein the catalyst mixture comprises less than 50 percent ZSM-5 type of conversion catalyst.

10. The method of claim 6 wherein a portion of the catalyst separated from the first conversion zone is combined with catalyst separated from the second conversion zone and thereafter passed to catalyst regeneration.

11. The method of claim 6 wherein a portion of the catalyst separated from the second conversion zone is recycled thereto and another separated portion is passed to catalyst regeneration.

12. The method of claim 6 wherein the first hydrocarbon feed is a low molecular weight fraction and said second hydrocarbon feed is a high molecular weight fraction.

13. The method of claim 6 wherein said first hydrocarbon feed is a virgin gas oil and said second hydrocarbon feed is selected from one or more hydrocarbon materials comprising the group of coker gas oils, recycle oil and residual stocks.

14. The method of claim 6 wherein preheating of the first and second hydrocarbon feeds is relied upon to provide a portion of conversion heat requirements in each conversion zone.

15. The method of claim 6 wherein the concentration of active ZSM-5 type crystalline zeolite in the second conversion zone with respect to coke deactivated faujasite conversiOn catalyst is varied as a function of the quantity of previously used stripped catalyst passed thereto.

16. The process of claim 6 wherein the catalyst mixture comprises from 40 to 80 weight percent of the ZSM-5 type crystalline zeolite.