Appeal No. 94-2855
Application 07/887,404
amine solution of Kniel is regenerated in unit 23 by withdrawing
acid gas through overhead line 24. Kniel does not disclose
regenerating degradation products of the alkanolamine in any way,
let alone by means of the hydrogenation step claimed by
appellant. However, the key to the examiner's rejection is
Kniel's disclosure that a hydrocarbon solvent is mixed with the
alkanol amine solution to remove troublesome dienes which tend to
polymerize and foul the system. Since Sze discloses separating
dienes from a gaseous stream also containing aromatic
hydrocarbons by treating the stream with hydrogen and a
hydrogenation catalyst, the examiner reasons that it would have
been obvious for one of ordinary skill in the art to treat the
diene-containing stream of Kniel with Sze's hydrogenation step to
separate the dienes therefrom, and thereby inherently effect
appellant's conversion of alkanolamine degradation products to
alkanol amines.
The flaw in the examiner's reasoning is two-fold. First,
since Kniel removes dienes from the spent alkanolamine solution
by addition of a hydrocarbon solvent, and Sze discloses
hydrogenation for separating dienes and the like from aromatic
compounds, there would have been no motivation for one of
ordinary skill in the art to modify the Kniel process by
replacing the treatment with hydrocarbon solvent with Sze's
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