Appeal No. 2002-2266 Page 3
Application No. 09/366,477
OPINION
The Rejection of Claims 1-20 over Abichandani and Chang
We have selected claim 1 to represent the issues on appeal for the rejection of claims 1-20
over Abichandani and Chang. Claim 1 reads as follows:
1. A plural stage toluene conversion process for preparing xylenes comprising:
i) contacting in a first stage toluene disproportionation zone a reaction stream comprising
toluene and hydrogen with a first stage catalyst comprising catalytic acid molecular sieve which
catalyst is substantially free of hydrogenation metal, under toluene disproportionation reaction
conditions sufficient to provide a first stage effluent comprising para-xylene and ethylbenzene;
and
ii) contacting said effluent from the first stage in a subsequent stage ethylbenzene
abatement zone with a subsequent stage catalyst containing porous selectivated catalytic
molecular sieve comprising a hydrogenation metal which catalyst is selectivated by treating with
a selectivating agent which hinders entry of xylene isomers and permits entry of ethylbenzene
into the pores of said subsequent stage catalyst molecular sieve, at reaction conditions sufficient
to selectively convert said ethylbenzene to benzene and ethane in the presence of xylenes and
toluene to provide a subsequent stage product containing para-xylene and having reduced
ethylbenzene content relative to the effluent from said first stage.
Claim 1 is directed to a process for toluene disproportionation which produces xylenes
and minimizes ethylbenzene production. It is a two-stage process. In the first stage, a catalyst,
which is substantially free of hydrogenation metal, is used to convert toluene and hydrogen to
para-xylene. The reaction produces ethylbenzene, an unwanted by-product. The ethylbenzene
containing effluent from the first stage is fed to a second stage ethylbenezene abatement zone. In
the second stage, a catalyst containing a hydrogenation metal is used to selectively convert
ethylbenzene to benzene and ethane.
Page: Previous 1 2 3 4 5 6 7 8 9 10 11 12 13 Next
Last modified: November 3, 2007