Claims
- 1. A process for preparing a catalyst for the dehydrocyclodimerization of C2-C6 aliphatic hydrocarbons, the process comprising:a) forming a bound zeolite comprising a zeolite having a silica to alumina molar ratio greater than about 20 and a pore diameter from about 5 Å to about 6 Å, and an essentially non-acidic binder; b) calcining the bound zeolite at a temperature from about 450° C. to about 700° C. for a period from about 1 to about 20 hours to yield a calcined composite; c) contacting the calcined composite with an aqueous solution of a gallium metal salt selected from the group consisting of gallium nitrate, gallium chloride, gallium bromide, gallium hydroxide, and gallium acetate to yield a gallium-impregnated composite; d) reducing the gallium-impregnated composite at a temperature from about 400° C. to about 700° C. for a period from about 1 to about 10 hours in a hydrogen-containing gas to yield a reduced gallium impregnated composite; e) oxidizing the reduced gallium impregnated composite at a temperature from about 400° C. to about 700° C. for a period from about 1 to about 10 hours in an oxidizing atmosphere comprising air and steam where the steam is present in an amount from about 1% to 100% of saturation to yield the catalyst.
- 2. The process of claim 1 where the bound zeolite is formed by extrusion or oil dropping.
- 3. The process of claim 1 where the calcined composite and gallium metal salt solution are contacted by evaporative impregnation.
- 4. The process of claim 1 further comprising contacting the calcined composite with an aqueous solution of a promoter metal salt where the promoter metal is selected from the group consisting of indium, molybdenum, zinc, tin, and mixtures thereof.
- 5. The process of claim 1 where, after step (b), the calcined composite is steamed at a temperature from about 600° C. to about 1200° C. and an absolute pressure from about 1 to about 20 atmospheres for a period of at least about 1 hour in a steaming atmosphere comprising steam present in an amount from about 5% to 100% of saturation.
- 6. The process of claim 5 further comprising contacting the calcined composite with an aqueous solution of a promoter metal salt where the promoter metal is selected from the group consisting of indium molybdenum, zinc, tin, and mixtures thereof.
- 7. The process of claim 1 where the process further comprises washing the calcined composite with a wash solution selected from the group consisting of ammonium nitrate, a mineral acid, and water.
- 8. The process of claim 1 where the calcined composite is ion-exchanged with an ion-exchange solution of a salt comprising a hydrogen-forming cation of ammonium ion or a quaternary ammonium ion.
- 9. The process of claim 8 further comprising contacting the calcined composite with an aqueous solution of a promoter metal salt where the promoter metal is selected from the group consisting of indium, molybdenum, zinc, tin, and mixtures thereof.
- 10. The process of claim 1 where the binder is selected from the group consisting of silica, zirconia, titania, and mixtures thereof.
- 11. The process of claim 10 where the binder is silica.
- 12. The process of claim 1 where the zeolite is an MFI structure type zeolite.
- 13. The process of claim 1 where the zeolite is present in amount from about 30% to about 90% by weight of the catalyst.
- 14. The process of claim 1 where the gallium metal is present in an amount from about 0.1% to about 5% by weight of the catalyst.
CROSS-REFERENCE TO RELATED APPLICATION
This application is a division of U.S. application Ser. No. 09/466,452 filed on Dec. 17, 1999, now abandoned the contents of which are hereby incorporated by reference.
US Referenced Citations (18)
Foreign Referenced Citations (1)
Number |
Date |
Country |
1 496 379 |
Dec 1977 |
GB |