Appeal 2007-3383
Application 10/452,939
We have considered, and are unpersuaded by, Appellants’ arguments
and the evidence contained in the Kasztelan Declaration for the reasons
below.
Tellier discloses that a weak point in the use of catalysts in the Claus
process for recovering sulphur is that the catalyst is very sensitive to oxygen
in the gas to be processed (Tellier, col. 1, ll. 37-47). Tellier discloses the
following two embodiments to address the presence of oxygen: (1)
modifying the Claus reactors where the sulphur is formed by replacing part
of the traditional catalyst at the reactor inlet by an oxide catalyst containing
transition metals, or (2) preceding the traditional Claus reactors with a
deoxidation reactor charged with a catalyst containing a transition metal
compound (Tellier, col. 2, ll. 12-29). Tellier discloses that the Claus process
generally uses several converters (i.e., reactors) in series (Tellier, col. 1,
ll. 19-21). Tellier further claims “at least one catalytic reaction zone [i.e.,
reactor] containing a deoxidation catalyst and a Claus oxide catalyst”
(Tellier, claim 1).
Burmaster discloses that it is known that Claus installations are
susceptible to catalyst fouling and deactivation caused by hydrocarbons,
especially aromatic hydrocarbons like benzene, toluene and xylenes
(Burmaster, col. 3, ll. 4-26).
Michel, like Tellier, discloses that it is known that the Claus reaction
generally includes a series of catalytic stages (Michel, col. 1, ll. 35-45).
Based on these disclosures, the applied prior art would have provided
motivation for combining Burmaster’s disclosure to decrease the amount of
aromatic hydrocarbons in the feed gas and Michel’s use of a series of
multiple stages as is known in the Claus process with Tellier’s method of
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