Appeal No. 2002-2266 Page 5
Application No. 09/366,477
hydrogenation metal to reduce ethylbenzene (col. 13, ll. 7-10 and 31-34). Chang recognizes the
problem of ethylbenzene abatement and discusses two second stage ethylbenzene abatement
processes; isomerization and superfractionation (col. 13, ll. 21-22). According to Chang, these
processes are either impractical or expensive (col. 13, ll. 22-30).
Abichandani also notes that separation or removal of ethylbenzene from mixed xylene
streams is frequently difficult and expensive (col. 2, ll. 37-40). Abichandani describes an
alternative process of using a selectivated catalyst which may contain a hydrogenation metal to
convert ethylbenzene with low xylene loss (col. 1, ll. 15-19 and col. 8, l. 56 to col. 6, l. 6).
Abichandani specifically suggests using the effluent from a toluene disproportionation reaction
as the feedstock for the selective ethylbenzene conversion process, i.e., Abichandani suggests a
two step process of disproportionation followed by ethylbenzene abatement (col. 4, l. 65 to col.
5, l. 3).
Chang and Abichandani together suggest that at least four methods of reducing
ethylbenzene were known: the two-stage processes in which ethylbenzene is separated by
isomerization or superfractionation after disproportionation; the two-stage process of selective
conversion of ethylbenzene after disproportionation as taught by Abichandani; and the one-stage
process of the second embodiment of Chang. While Chang describes the two-stage processes
including isomerization and superfractionation as inferior, Chang does not teach away from using
the selective ethylbenzene conversion of Abichandani. In fact, Abichandani suggests the
combination of the two steps (col. 4, l. 61 to col. 5, l. 3).
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