Claims
- 1. A process for treating a zeolite-based catalyst, said catalyst comprising a crystalline zeolite material characterized by a silica-to-alumina ratio of at least 12 and a constraint index of from about 1 to 12, and from about 0.25% to 25% by weight of a modifying oxide selected from magnesium oxide, phosphorus oxide and mixtures of said oxides, said process comprising pretreating said catalyst with a gaseous medium containing a halogen-based pretreating agent selected from HCl, HBr, Cl.sub.2, Br.sub.2, and mixtures thereof, under conditions including contacting the zeolite catalyst with the pretreating agent at a temperature of from about 15.degree. C. to 300.degree. C. for a period of from about 0.1 to 25 hours, followed by calcination of the treated catalyst at a temperature of from about 300.degree. C. to 600.degree. C., thereby enhancing the para-selectivity of said catalyst in the subsequent conversion of aromatic compounds to dialkyl-substituted benzene compounds.
- 2. A process according to claim 1 wherein said zeolite is selected from ZSM-5, ZSM-11, ZSM-12, ZSM-23, ZSM-35, ZSM-38 and ZSM-48.
- 3. A process according to claim 1 wherein said halogen-based pretreating agent provided in a treating medium comprising from about 5% to 100% by volume of said pretreating agent.
- 4. A process according to claim 3 wherein said treating medium is passed over said catalyst at the rate of from about 5 to 100 cc/min/gm catalyst for a period of from about 0.1 to 1 hour.
- 5. A process according to claim 4 wherein said treating medium comprises 100% by volume of anhydrous HCl.
- 6. A catalyst composition prepared in accordance with the process of claim 1, 2, 3, 4 or 5.
- 7. A catalyst composition according to claim 6 comprising from about 1% to 99% by weight of zeolite material with the balance of said composition comprising a binder for said zeolite material.
Parent Case Info
This is a division of application Ser. No. 277,483 filed June 26, 1981, now U.S. Pat. No. 4,361,713.
US Referenced Citations (8)
Non-Patent Literature Citations (2)
Entry |
Yashima et al., "Journal of Catalysis" 17, 151-156, 1970. |
Minachev et al., "Chemistry Reviews", vol. 2 (1980), pp. 1-6. |
Divisions (1)
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Number |
Date |
Country |
Parent |
277483 |
Jun 1981 |
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