Appeal 2007-1943
Application 10/443,649
4,166,026 to Fukui et al. Generally, the hydrodesulfurization contacts
a hydrocarbon oil with hydrogen in the presence of a catalyst.
It is, however, well known that hydrotreating reduces the
aromaticity of hydrocarbon oils . . . . The references, “Catalysis”,
Vol. V, edited by P. H. Emmett, published by Rheinhold Publishing
Corp., New York, 1957, and “Catalytic Processes and Proven
Catalysts”, edited by C. L. Thomas, Academic Press (1970), point out
that hydrotreating reduces aromaticity.
Persons having ordinary skill in the art would have understood from
Didchenko’s statement that “[i]t is . . . well known that hydrotreating
reduces the aromaticity of hydrocarbon oils” and “hydrotreating reduces
aromaticity” (id.) that well known desulfurization hydrotreatment of high
sulfur decant oils hydrogenates “a significant portion of the aromatic
hydrocarbons, particularly the polycyclic hydrocarbons . . .” (Col. 1,
ll. 38-40, of Skripek et al, U.S. Pat. 4,075,084, patented February 21, 1978,
cited by Didchenko, col. 3, ll. 4-6, as disclosing a known process).
Therefore, persons having ordinary skill in the art reasonably would have
expected well known hydrotreatment of high sulfur decant oils to reduce
whatever level of PAH was initially present in Appellants’ “supply of
petroleum feedstock of relatively high sulfur content fractions derived from
crude oil having an initial sulfur content of about 1 wt% or greater” (Br.
App. Claim 1) and “supply of petroleum feedstock of relatively high sulfur
content fractions derived from crude oil having an initial sulfur content of
about 2 wt% or greater” (Br. App. Claim 11). In our view, therefore, a
person having ordinary skill in the art would have reasonably predicted that
Didchenko’s hydrotreatment step not only would have reduced the sulfur
content of its initial decant oil, but also would have hydrogenated, and thus
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