Claims
- 1. A process for the production of para-xylene, which process comprises:
(a) providing a reformate comprising: (i) hydrogen; (ii) C1-C5 hydrocarbons, (iii) C6-C7 aromatic hydrocarbons comprising benzene, toluene or mixtures thereof, (iv) C8+ aromatic hydrocarbons; and, (v) and up to 70 weight percent of non-aromatic C6-C8 hydrocarbons based on the weight of the C6-C7 hydrocarbons present in the feed stream; (b) methylating at least a portion of said benzene, toluene, or mixtures thereof present in said reformate in a methylation reaction zone with a methylating agent under vapor phase conditions effective for the methylation and in the presence of an acidic molecular sieve catalyst to produce a product containing a reduced amount of C6-C8 non-aromatic hydrocarbons compared to the reformate and xylenes.
- 2. The process recited in claim 1, wherein said acidic molecular sieve catalyst is para-selective.
- 3. The process recited in claim 2, wherein at least 60 percent of the xylenes produced in the methylation are para-xylene.
- 4. The process recited in claim 3, wherein said reformate is formed by the catalytic reforming.
- 5. The process of claim 4, further comprising removing from said reformate at least a portion of said hydrogen, said C1-C5 hydrocarbons, and said C8+ aromatic hydrocarbons.
- 6. The process of claim 4, wherein substantially all of the C1-C5 hydrocarbons and the C8+ aromatic hydrocarbons are removed from said reformate before methylation.
- 7. A process recited in claim 4, wherein said para-selective molecular sieve catalyst comprises an intermediate pore size molecular sieve.
- 8. The process recited in claim 7, wherein said intermediate pore size molecular sieve is selected from the group consisting of ZSM-5, ZSM-11, ZSM-12, ZSM-22, ZSM-23, ZSM-34, ZSM-35, ZSM-38, ZSM-48, ZSM-50, ZSM-57, MCM-22, MCM-49, MCM-56, and SAPO-11.
- 9. The process recited in claim 8, wherein said molecular sieve is ZSM-5.
- 10. The process recited in claim 4, wherein hydrogen is supplied to said methylation reaction zone.
- 11. The process recited in claim 4, said methylation is conducted in the presence of hydrogen and/or added water such that the molar ratio of hydrogen and/or added water to C6-C7 aromatic hydrocarbons and methylating agent is between about 0.01 and about 100.
- 12. The process recited in claim 6, wherein step (b) is carried out in a fluidized bed.
- 13. The process recited in claim 6, wherein step (b) is carried out in a fixed bed.
- 14. The process recited in claim 4, wherein said methylation conditions include a temperature from about 400° C. to about 700° C., a pressure from about 1 to 1000 psig, and a molar ratio of methylating agent to toluene and benzene between about 0.1:1 to about 20:1.
- 15. The process recited in claim 14, wherein said feed stream is passed over said para-selective molecular sieve catalyst at a space velocity between about 0.1 and about 100 parts by weight of C6-C7 aromatic hydrocarbons.
- 16. The process recited in claim 8, wherein said para-selective molecular sieve catalyst is treated with 50% to about 100% steam at a temperature of from about 800° C. to about 1200° C., at a pressure of from about 0.1 to about 50 psia for a period of about 0.1 to about twelve hours
- 17. The process recited in claim 8, wherein said reformate is produced by CCR.
- 18. The process recited in claim 8, wherein said reformate contains up to 20 weight percent of non-aromatic C6-C8 hydrocarbons based on the weight of the C6-C7 hydrocarbons present in the feed stream
- 19. The process recited in claim 8, wherein said para-selective molecular sieve catalyst comprises a selectivating agent.
- 20. The process recited in claim 17, wherein said a selectivating agent is selected from the group consisting of silica, coke, phosphorus, alkaline earth metal oxides, rare earth metal oxides, lanthanum oxide, boron oxide, titania, antimony oxide, manganese oxide, and mixtures thereof.
- 21. The process recited in claim 21, wherein said molecular sieve is ZSM-5.
- 22. The process recited in claim 4, further comprising the step of recovering the para-xylene from said resulting product.
- 23. The process recited in claim 4, wherein said methylating agent is selected from the group consisting of methanol, dimethylether, methylchloride, methylbromide, methylcarbonate, acetaldehyde, dimethoxyethane, acetone, and dimethylsulfide.
- 24. The process recited in claim 23, wherein said methylating agent is injected into said methylation reaction zone through more than one feed point.
- 25. The process recited in claim 4, wherein at least 7 weight percent of the benzene and/or toluene present in said reformate is converted to xylenes.
- 26. The process recited in claim 4, wherein the resulting product contains contains more than 75 weight percent of para-xylene based on the total weight of the xylenes produced by said process.
- 27. The process recited in claim 4, wherein the amount of methylating agent reacted to form xylenes is at least 50 percent.
- 28. The process recited in claim 4, wherein the total amount of C6-C8 non-aromatic hydrocarbons are cracked to lower molecular weight products is at least 50 weight percent of the C6-C8 non-aromatic hydrocarbons present in said reformate.
- 29. The process recited in claim 4, wherein the resulting product contains more than 80 weight percent of para-xylene based on the total weight of the xylenes produced by said process.
- 30. The process recited in claim 3, wherein said reformate is formed by the dehydrocyclo-oligomerization of C2-C5 aliphatics.
- 31. The process recited in claim 3, wherein said reformate is formed by the cracking of hydrocarbons.
- 32. The process recited in claim 30, wherein said cracking of hydrocarbons is accomplished in a catalytic cracking process.
- 33. The process recited in claim 31, wherein said cracking of hydrocarbons is accomplished in a steam cracking process.
REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of application Ser. No. 10/465,058, filed Jun. 18, 2003, which claims priority to provisional application Serial No. 60/389,977, filed Jun. 19, 2002.
Provisional Applications (1)
|
Number |
Date |
Country |
|
60389977 |
Jun 2002 |
US |
Continuation in Parts (1)
|
Number |
Date |
Country |
Parent |
10465058 |
Jun 2003 |
US |
Child |
10746074 |
Dec 2003 |
US |