Aromatics isomerization using a dual-catalyst system

• US 6,576,581 B1
• Filed: 12/21/2000
• Issued: 06/10/2003
• Est. Priority Date: 07/02/1999
• Status: Expired due to Fees

• Current Assignee: UOP Llc (Honeywell International Inc.)
• Original Assignee: UOP Llc (Honeywell International Inc.)
• Inventors: Imrie, Aaron J., Sharma, Sanjay B.
• Primary Examiner(s): Dunn, Tom
• Assistant Examiner(s): Ildebrando, Christina
• Application Number:
  US09/746,584
• Time in Patent Office: 901 Days
• Field of Search: 502/60, 502/64, 502/66, 502/71, 502/67, 502/74, 502/77, 502/208, 502/213, 502/214
• US Class Current: 502/66
• CPC Class Codes: B01J 2229/20 to introduce other elements in the catalyst composition comprising the molecular sieve, but not specially in or on the molecular sieve itself
• CPC Class Codes: B01J 2229/36 Steaming
• CPC Class Codes: B01J 2229/42 Addition of matrix or binder particles
• CPC Class Codes: B01J 29/005 Mixtures of molecular sieves comprising at least one molecular sieve which is not an aluminosilicate zeolite, e.g. from groups B01J29/03 - B01J29/049 or B01J29/82 - B01J29/89
• CPC Class Codes: B01J 29/12 Noble metals
• CPC Class Codes: B01J 29/22 Noble metals
• CPC Class Codes: B01J 29/44 Noble metals
• CPC Class Codes: B01J 29/67 Noble metals
• CPC Class Codes: B01J 29/74 Noble metals
• CPC Class Codes: B01J 29/7446 EUO-type, e.g. EU-1, TPZ-3 or ZSM-50
• CPC Class Codes: B01J 29/7453 MFS-type, e.g. ZSM-57
• CPC Class Codes: B01J 29/7469 MTW-type, e.g. ZSM-12, NU-13, TPZ-12 or Theta-3
• CPC Class Codes: B01J 29/7484 TON-type, e.g. Theta-1, ISI-1, KZ-2, NU-10 or ZSM-22
• CPC Class Codes: B01J 29/84 Aluminophosphates containing other elements, e.g. metals, boron
• CPC Class Codes: B01J 29/85 Silicoaluminophosphates [SAPO compounds]
• CPC Class Codes: C07C 15/067 C8H10 hydrocarbons
• CPC Class Codes: C07C 2523/40 of the platinum group metals
• CPC Class Codes: C07C 2529/04 having base-exchange properties, e.g. crystalline zeolites, pillared clays
• CPC Class Codes: C07C 2529/068 Noble metals
• CPC Class Codes: C07C 5/2724 with metals

Abstract

This invention is drawn to a catalyst system comprising two or more molecular sieves, including at least one non-zeolitic molecular sieve and one zeolitic aluminosilicate, having specified contrasting pore structures and to a process for isomerizing a non-equilibrium mixture of xylenes and ethylbenzene using the subject catalyst system to obtain an improved yield of para-xylene from the mixture relative to prior-art processes.

Claims

1. A catalyst system comprising a combination of:

(a) a first catalyst comprising from about 0.1 to 2 mass-% of at least one platinum-group metal component, about 10 to 90 mass-% of at least one non-zeolitic molecular sieve, and an inorganic-oxide binder; and

,

(b) a second catalyst comprising from about 0.02 to 0.08 mass-% of at least one platinum-group metal component, from about 10 to 99 mass-% of at least one zeolitic aluminosilicate, and an inorganic-oxide binder, wherein the content of platinum-group metal is no more than about 30% of the content of platinum-group metal in the first catalyst.

2. The catalyst system of claim 1 wherein the content of platinum-group metal in the second catalyst is no more than about 20% of the content of platinum-group metal in the first catalyst.

3. The catalyst system of claim 2 wherein the content of platinum-group metal in the second catalyst is no more than about 10% of the content of platinum-group metal in the first catalyst.

4. The catalyst system of claim 1 wherein the second catalyst comprises less than about 0.06 mass-% of platinum-group metal.

5. The catalyst system of claim 1 wherein the non-zeolitic molecular sieve of the first catalyst comprises a crystalline SAPO-11 molecular sieve.

6. The catalyst system of claim 5 wherein the crystalline SAPO-11 molecular sieve is an SM-3 molecular sieve.

7. The catalyst system of claim 1 wherein the non-zeolitic molecular sieve of the first catalyst comprises a MgAPSO-31 molecular sieve.

8. The catalyst system of claim 7 wherein the MgAPSO-31 molecular sieve has a framework magnesium content of from about 0.03 to 0.035 mole fraction.

9. The catalyst system of claim 1 wherein a first:

second catalyst mass ratio is from about 1;

20 to 50;

1.

10. The catalyst system of claim 1 comprising a physical mixture of first particles comprising the non-zeolitic molecular sieve and second particles comprising the zeolitic aluminosilicate.