Process for the regioselective conversion of aromatics to para-disubstituted benzenes
AssigneeMobil Oil Corporation
InventorsClarence D. Chang, Paul G. Rodewald
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Abstract
Processes for converting a wide variety of aromatic hydrocarbons, such as polyalkylaromatics, into commercially useful para-substituted aromatics such as para-xylene are disclosed. The aromatic hydrocarbon feed stream is first partially converted into toluene which is then subjected to a highly para-selective methylation process. The present invention therefore provides novel processes and catalysts for increasing the para-selectivity in the selective production of para-substituted aromatic compounds. From the description provided herein, those skilled in the art will appreciate that the catalysts and processes of the present invention provide greater para-selectivity at conversion rates unattained by previously known methods.
Claims25
A process for the regioselective conversion of a C.sub.6-10 mononuclear aromatic hydrocarbon mixture to para-xylene comprising the steps of:
- (i) contacting said aromatic mixture with a first catalytic molecular sieve at first reaction conditions suitable for transalkylating a portion of said aromatic mixture to toluene in a first reaction to form an intermediate product stream containing toluene;
- and
- (ii) disproportionating by contacting said toluene with a second catalytic molecular sieve, at second reaction conditions suitable to provide a p-xylene conversion product with a para-substituted benzene purity of at least about 90% with a toluene conversion of at least about 15%.
A process for the regioselective conversion of a mixture of isomeric xylenes to para-xylene comprising:
- (i) transalkylating a mixture of isomeric xylenes with benzene in the presence of a first molecular sieve catalyst to form a product mixture containing toluene;
- and
- (ii) disproportionating the toluene in the presence of a second molecular sieve catalyst under reaction conditions providing a conversion product comprising at least 20 percent xylene with a para-xylene purity of at least 90 percent.
Dependencies are inferred from the claim text.