November 21, 2011

CAS databases provide millions of journal article references from more than 10,000 major scientific journals worldwide, patent and patent family references from 61 patent authorities around the world, and other reputable web sources.

The following patent record is from the CAplusSM database.


Patent Number: US 8048388
Title: p-Xylene manufacture from pyrolysis gasoline by zeolite-catalyzed methylation and dealkylation
Inventor(s): Brown, Stephen Harold; Buchanan, John Scott
Patent Assignee(s): ExxonMobil Chemical Patents, Inc., USA
Source: U.S. Pat. Appl. Publ., 20 pp. CODEN: USXXCO
Language: English


The process produces p-xylene from a pyrolysis gasoline with a porous crystalline catalyst (especially ZSM-5 and -11). The process comprises contacting the feedstock and the catalyst at 500-700 degree C; and separating p-xylene from the product by using a mol. sieve having a Diffusion Parameter for 2,2-dimethylbutane of .apprx.0.1-15 s-1 at 120 degree C and 8 kPa-a. The catalyst contains modifiers, oxides of elements of Groups 2, 3, 4, 5, 6, 13, 14, and 15 (especially B, Mg, Ca, La, and P). The process produces p-xylene in high yield, and prevents rapid catalyst deactivation.

Please note:  Abstracts and titles for patent records in CAplus are routinely enhanced to better describe the claimed invention. In this example, CAS enhanced the title using additional information found in the patent. The original title of the U.S. granted patent is Process of manufacturing para-xylene. For the CAplus record, this title was enhanced to read p-Xylene manufacture from pyrolysis gasoline by zeolite-catalyzed methylation and dealkylation.

View the full-text U.S. patent from USPTO.


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