Appeal 2006-2691
Application 09/942,830
specification the term ultra-deep HDS means the reduction of the sulfur
content of a hydrocarbon feedstock to a value of less than about 200 ppm”
(Specification 2: 4-5; see also 2:27 and 5:18-22). Hatanaka teaches three
reaction zones with appropriate catalysts and conditions, where in the first
zone sulfur compounds other than 4-methyl and 4,6-dimethyl
dibenzothiophenes are removed, in the second zone the 4-methyl and 4,6-
dimethyl benzothiophenes are removed, and in the third zone the thiol and
sulfide by-products of the second zone are removed to reach the final desired
sulfur content of from 1 to 50 ppm (Hatanaka, cols. 3-5). Hatanaka, in the
second zone, uses “the best catalyst for each hydrogenation zone,” i.e.,
nickel and tungsten, to remove 4-methyl and 4,6-dimethyl benzothiophenes
and effect ultra-deep HDS (Hatanaka 5:27-47 and 61-67), while Appellants
claim the same catalysts and process conditions “[t]o effect ultra-deep HDS
…, the last compounds present, in particular a limited number of alkylated
benzothiophenes, need to be removed …, with the alkylbenzothiophenes
which have the alkyl on the 4- or 6- position being particularly difficult to
remove.” (Specification 2:27-31). Accordingly, we find that Hatanaka and
the claimed process employ the same catalysts and process conditions to
effect the same reaction and remove the same undesired sulfur compounds to
the same levels.
We find that Hatanaka teaches that the active metal content in a
“conventional desulfurization catalyst” can be adopted as the active metal
content contained in the catalyst of the first and second hydrogenation zones
of the invention (Hatanaka 6:15-19). We further find that Hatanaka teaches
that the catalyst should first be presulfided (Hatanaka 8:40; see also
5
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