Distinguishing the claimed invention from conventional implementations may constitute a clear disclaimer that one or more claim limitations do not cover such conventional implementations. Here, for example, the claimed “fractionating” was found to exclude conventional extraction of hydrocarbon compounds because the specification and prosecution history touted the benefits of the invention over conventional extraction methods. “[I]mportantly, the patentee made clear and unmistakable statements in the intrinsic record, distinguishing the claimed invention from and disclaiming conventional [such] methods.” It may therefore be best to avoid espousing the benefits of the claimed invention as a whole over the prior art if certain limitations are intended to encompass aspects of the prior art.
Background / Facts: The patent being asserted here is directed to a process for the coproduction of ethylene and purified benzene from refinery mixtures. The claims recite “fractionating” a pyrolysis gasoline to form “a purified benzene product comprising at least about 80 wt % of benzene.”
Issue(s): Whether the term “fractionating” should be construed to mean “conventional distillation, i.e., separating compounds based on difference in their boiling points,” which excludes extraction, i.e., separating compounds based on solubility differences.
Holding(s): Yes. “The specification repeatedly and consistently uses ‘fractionating’ or ‘fractionation’ to describe separating petrochemicals based on boiling point differentials. Moreover, importantly, the patentee made clear and unmistakable statements in the intrinsic record, distinguishing the claimed invention from and disclaiming conventional extraction methods that produce 99.9% pure benzene.” For example, “the patentee twice stated during prosecution that the claimed process is ‘particularly useful’ ‘to produce a benzene product that need not have a purity over 99 wt%, much less over 99.9 wt%, as previously required.’ [] Those clear statements indicate that the inventor contemplated the claimed invention to be different from conventional extraction, which produces highly pure, nitration-grade 99.9% benzene.”