  United States Court of Appeals
      for the Federal Circuit
                 ______________________

 DAVID NETZER CONSULTING ENGINEER LLC,
             Plaintiff-Appellant

                            v.

  SHELL OIL COMPANY, SHELL CHEMICAL LP,
    SHELL OIL PRODUCTS COMPANY LLC,
              Defendants-Appellees
             ______________________

                       2015-2086
                 ______________________

   Appeal from the United States District Court for the
Southern District of Texas in No. 4:14-cv-00166, Judge
Lynn N. Hughes.
                ______________________

                 Decided: May 27, 2016
                 ______________________

    ANTHONY MATTHEW GARZA, Charhon Callahan Robson
& Garza, P.C., Dallas, TX, argued for plaintiff-appellant.
Also represented by STEVEN CHASE CALLAHAN.

    KATHLEEN M. SULLIVAN, Quinn Emanuel Urquhart &
Sullivan, LLP, New York, NY, argued for defendants-
appellees. Also represented by KEVIN ALEXANDER SMITH,
San Francisco, CA; JOSHUA L. SOHN, Washington, DC;
CHARLES BRUCE WALKER, JR., Norton Rose Fulbright US
LLP, Houston, TX; JAYME PARTRIDGE, Patterson & Sheri-
dan LLP, Houston, TX.
2                        DAVID NETZER v. SHELL OIL COMPANY




                 ______________________

    Before PROST, Chief Judge, LOURIE and TARANTO,
                    Circuit Judges.
LOURIE, Circuit Judge.
    David Netzer Consulting Engineer LLC (“Netzer”) *
appeals from the decision of the United States District
Court for the Southern District of Texas granting sum-
mary judgment of noninfringement of the asserted claims
of U.S. Patent 6,677,496 (“the ’496 patent”). David Netzer
Consulting Eng’r LLC v. Shell Oil Co., No. 4:14-cv-00166,
ECF No. 45 (S.D. Tex. Aug. 26, 2015) (“Decision”). For the
reasons that follow, we affirm.
                      BACKGROUND
    Netzer owns the ’496 patent, entitled “Process for the
Coproduction of Benzene from Refinery Sources and
Ethylene by Steam Cracking,” which describes a process
for the coproduction of ethylene and purified benzene
from refinery mixtures. Claim 1, the sole independent
claim, reads as follows:
    1. A process for the coproduction of ethylene and
       purified benzene comprising:
        providing a first mixture comprising benzene,
          toluene, and one or more C6 to C7 non-
          aromatics;
        separating the majority of the benzene and the
          one or more C6 to C7 non-aromatics from the
          majority of the toluene to form a second
          mixture containing at least a portion of the



    *  As indicated infra, in March 2014, David Netzer
Consulting Engineer LLC changed its name to David
Netzer – Petrochemicals Consultant LLC.
DAVID NETZER v. SHELL OIL COMPANY                          3



         benzene and at least a portion of the one or
         more C6 to C7 non-aromatics, wherein the
         second mixture is substantially free of hy-
         drocarbons having more than nine carbons;
       introducing at least a portion of the second
          mixture to a cracker and thereafter cracking
          at least about 80% of the C6 to C7 non-
          aromatics in the portion of the second mix-
          ture that has been introduced to the cracker
          while maintaining essentially no cracking of
          benzene to produce a cracked product con-
          taining ethylene, propylene and pyrolysis
          gasoline comprising olefins, di-olefins and
          benzene; and
       fractionating the pyrolysis gasoline to form a
          purified benzene product comprising at least
          about 80 wt % benzene.
’496 patent col. 7 ll. 11–32 (emphases added).
    The claimed process thus requires four steps: (1) pro-
viding a mixture containing benzene, toluene, and C6–C7
non-aromatic hydrocarbons; (2) separating most of the
benzene and C6–C7 non-aromatic hydrocarbons from most
of the toluene; (3) introducing the benzene-rich stream
into a cracker, i.e., a reactor that breaks down long-chain
hydrocarbons to short-chain hydrocarbons, and then
cracking the C6–C7 non-aromatic hydrocarbons to produce
ethylene and pyrolysis gasoline; and (4) “fractionating the
pyrolysis gasoline to form a purified benzene product
comprising at least about 80 wt % of benzene” (“the frac-
tionating step”).
    On January 23, 2014, David Netzer, the sole inventor
of the ’496 patent, assigned the patent to Netzer, a limited
liability company newly formed under Texas law. J.A. 85
(assignment); J.A. 81–83 (Certificate of Filing issued by
the Secretary of State). The next day, Netzer sued Shell
4                        DAVID NETZER v. SHELL OIL COMPANY




Oil Company, Shell Chemical LP, and Shell Oil Products
Company LLC (collectively, “Shell”) in the United States
District Court for the Southern District of Texas, alleging
that Shell infringed the ’496 patent. Shortly thereafter,
the State of Texas requested that Netzer remove the word
“Engineer” from its name.       In March 2014, Netzer
changed its name from David Netzer Consulting Engineer
LLC to David Netzer – Petrochemicals Consultant LLC
through a Certificate of Correction. J.A. 78–79, 87–88.
Meanwhile, Shell answered and counterclaimed for a
declaratory judgment of noninfringement and invalidity
in the district court.
     Shell then moved for summary judgment of non-
infringement. Shell argued that 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. Shell argued
that the patentee disclaimed extraction in the specifica-
tion and prosecution history. According to Shell, its
accused process does not meet the fractionating step
because it uses extraction—more specifically, the Sul-
folane process developed by Shell in the 1960s—to form a
benzene product with 99.9% purity. Netzer responded
that “fractionating” should be construed to mean “separat-
ing a chemical mixture into fractions, no matter the
process units used.” Examples of process units, according
to Netzer, include distillation columns (for separating
chemicals based on differences in boiling points), extrac-
tors (for separating chemicals based on solubility differ-
ences), and hydrotreaters (for hydrogenating unsaturated
hydrocarbons, such as olefins). Netzer also argued that
Shell infringes literally under either construction, and
that Shell also infringes under the doctrine of equivalents.
    The district court granted summary judgment of non-
infringement. The court did not formally construe the
claims, but, rather, implicitly agreed with Shell that
DAVID NETZER v. SHELL OIL COMPANY                           5



“fractionating” does not include extraction. The court
found no literal infringement, reasoning that “Netzer’s
method does not include extraction and does not yield
benzene of 99.9% purity” and that “[t]o infringe, Shell
would have to eliminate the extraction step and still
produce benzene purified to at least 80%.” Decision at 2.
The court also found no infringement under the doctrine
of equivalents because Netzer is barred by “specific exclu-
sion, prosecution-history estoppel, and prior art.” Id. at 3.
     The district court then entered final judgment in favor
of Shell. David Netzer Consulting Eng’r LLC v. Shell Oil
Co., No. 4:14-cv-00166, ECF No. 46 (S.D. Tex. Aug. 26,
2015). Netzer timely appealed to this court. However,
because Shell’s counterclaims remained pending in the
district court, this court granted the parties’ joint motion
for a limited remand. On that limited remand, the dis-
trict court dismissed Shell’s declaratory judgment coun-
terclaims without prejudice and then entered an amended
final judgment, thus disposing of all claims and counter-
claims. David Netzer Consulting Eng’r LLC v. Shell Oil
Co., No. 4:14-cv-00166, ECF No. 56 (S.D. Tex. Mar. 31,
2016). Netzer then filed a new notice of appeal, and its
appeal was reinstated in this court. We have jurisdiction
under 28 U.S.C. § 1295(a)(1).
                        DISCUSSION
                              I
    Before we reach the merits of Netzer’s appeal, Netzer
asks us to confirm that it has standing to maintain this
action. According to Netzer, on January 24, 2014, at the
inception of the lawsuit, an entity known as David Netzer
Consulting Engineer LLC held enforceable title to the
’496 patent pursuant to the January 23, 2014 assignment,
and thus had standing to sue. Netzer argues that the
March 2014 name change did not retroactively invalidate
the January 2014 assignment under Texas law. The
district court did not question Netzer’s standing.
6                        DAVID NETZER v. SHELL OIL COMPANY




    We agree with Netzer that it has standing to bring
and maintain this action. At the inception of the lawsuit,
the ’496 patent was assigned to the plaintiff entity, then
named David Netzer Consulting Engineer LLC. Although
that entity later changed its name to David Netzer –
Petrochemicals Consultant LLC as required by Texas law,
that name change did not undo the January 23, 2014
transfer of patent ownership. The patent was owned by
the same company, under its new name. We therefore
conclude that Netzer, as the owner of the ’496 patent as of
January 24, 2014, has standing to maintain this action.
                             II
    We turn now to the merits of Netzer’s appeal. When
reviewing a district court’s grant of summary judgment,
we apply the law of the regional circuit in which the
district court sits, here, the law of the Fifth Circuit. Teva
Pharm. Indus. Ltd. v. AstraZeneca Pharm. LP, 661 F.3d
1378, 1381 (Fed. Cir. 2011). The Fifth Circuit reviews a
district court’s summary judgment decision de novo,
applying the same standard used by the district court.
United States v. Caremark, Inc., 634 F.3d 808, 814 (5th
Cir. 2011). Summary judgment is appropriate when,
drawing all justifiable inferences in the nonmovant’s
favor, “there is no genuine dispute as to any material fact
and the movant is entitled to judgment as a matter of
law.” Fed. R. Civ. P. 56(a); Anderson v. Liberty Lobby,
Inc., 477 U.S. 242, 247–48 (1986).
    To determine infringement, a court first construes the
scope and meaning of the asserted patent claims, and
then compares the construed claims to the accused pro-
duct or process. Absolute Software, Inc. v. Stealth Signal,
Inc., 659 F.3d 1121, 1129 (Fed. Cir. 2011). “The proper
construction of a patent’s claims is an issue of Federal
Circuit law.” Id. We review a district court’s ultimate
claim constructions de novo and any underlying factual
determinations involving extrinsic evidence for clear
DAVID NETZER v. SHELL OIL COMPANY                          7



error. Teva Pharm. U.S.A., Inc. v. Sandoz, Inc., 135 S. Ct.
831, 841–42 (2015).
    Here, the district court did not make any factual find-
ings to support any claim construction. See Appellant’s
Br. 21. Its claim construction was implicit in its decision
of noninfringement. Because the intrinsic record alone
determines the proper construction in this case, we are
able to conduct our review adequately and we do so de
novo. See Shire Dev., LLC v. Watson Pharm., Inc., 787
F.3d 1359, 1364, 1368 (Fed. Cir. 2015) (citing Teva, 135 S.
Ct. at 840–42).
    Infringement is a question of fact. Absolute Software,
659 F.3d at 1129–30. “On appeal from a grant of sum-
mary judgment of non-infringement, we determine
whether, after resolving reasonable factual inferences in
favor of the patentee, the district court correctly conclud-
ed that no reasonable jury could find infringement.” Id.
                 A. Claim Construction
     The words of a claim “are generally given their ordi-
nary and customary meaning” as understood by a person
of ordinary skill in the art at the time of the invention.
Phillips v. AWH Corp., 415 F.3d 1303, 1312–13 (Fed. Cir.
2005) (en banc). Because that meaning is “often not
immediately apparent, and because patentees frequently
use terms idiosyncratically,” the court looks to the intrin-
sic record, including “the words of the claims themselves,
the remainder of the specification, [and] the prosecution
history,” as well as to extrinsic evidence when appro-
priate, to construe a disputed claim term. Id. at 1314,
1319. “[W]hile extrinsic evidence can shed useful light on
the relevant art, we have explained that it is less signifi-
cant than the intrinsic record in determining the legally
operative meaning of claim language.” Id. at 1317 (quota-
tion marks omitted).
8                          DAVID NETZER v. SHELL OIL COMPANY




    Because a patent is a fully integrated written instru-
ment, we have long emphasized the importance of the
specification in claim construction. Id. at 1315 (explain-
ing that the specification “is the single best guide to the
meaning of a disputed term”) (quoting Vitronics Corp. v.
Conceptronic, Inc., 90 F.3d. 1576, 1582 (Fed. Cir. 1996)).
Thus, if the specification reveals a special definition given
to a claim term by the inventor, then the inventor’s lexi-
cography governs, even if it differs from the term’s ordi-
nary meaning. Id. at 1316. Likewise, if the specification
reveals an intentional disclaimer or disavowal of claim
scope by the inventor, then the inventor’s intention as
expressed in the specification is regarded as dispositive.
Id. We have found disavowal or disclaimer based on clear
and unmistakable statement, such as “the present inven-
tion includes . . . ,” “the present invention is . . . ,” and “all
embodiments of the present invention are . . . .” Pacing
Techs., LLC v. Garmin Int’l, Inc., 778 F.3d 1021, 1024
(Fed. Cir. 2015).
    Netzer argues that “fractionating” means separating a
mixture into fractions, no matter what processes are used
to do so. According to Netzer, both the intrinsic record
and the extrinsic evidence suggest that fractionation
includes any method of separation, not limited to distilla-
tion. Netzer contends that the patentee did not disclaim
extraction by merely characterizing it as expensive in the
specification. Netzer additionally argues that the claim
only sets a lower limit on benzene purity, viz., “at least
about 80 wt %,” and thus does not exclude extraction,
which produces highly pure benzene. Netzer lastly argues
that “fractionating” ought to be construed to encompass
the disclosed preferred embodiment, so as to allow the
pyrolysis gasoline to pass through (a) more than one
process unit (in the preferred embodiment, a hydrotreater
and then two distillation columns), and (b) process units
that do not separate chemicals, such as a hydrotreater.
DAVID NETZER v. SHELL OIL COMPANY                          9



     Shell responds that “fractionating” should be con-
strued here to mean separating compounds based on
differences in boiling points, not generic “separating” by
any means. Shell argues that the intrinsic record compels
that construction, which cannot be altered by conflicting
extrinsic evidence. In particular, Shell contends that the
patent specification uses “fractionating” or “fractionation”
to describe separating compounds based on boiling points.
According to Shell, the patentee also disclaimed extrac-
tion in the specification by distinguishing it from “frac-
tionation” and by explaining that the claimed invention
was driven by a shift in market demand that no longer
required high purity benzene produced by extraction, such
as by the Sulfolane process.
    We agree with Shell that the claim term “fractionat-
ing” in this patent means separating compounds based on
differences in boiling points, i.e., distillation, which ex-
cludes extraction, such as in the Sulfolane process. The
specification repeatedly and consistently uses “fractionat-
ing” or “fractionation” to describe separating petrochemi-
cals 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.
    Specifically, the ’496 patent describes an “azeotrope”
problem. An azeotrope is a mixture of two or more com-
pounds that has a uniform boiling point; its components
vaporize together as a mixture and thus cannot be easily
separated from each other by distillation. J.A. 273. The
specification explains that certain C6–C7 non-aromatic
hydrocarbons form azeotropes with benzene, making it
“impossible” to separate benzene from that mixture by
“conventional fractionation.” ’496 patent col. 2 ll. 17–20.
The specification then discusses this issue in further
detail and refers to the azeotrope problem as “the conven-
tional fractionation issue.” Id. col. 3 ll. 18–35. Thus, the
10                          DAVID NETZER v. SHELL OIL COMPANY




patentee used “conventional fractionation” to refer to
conventional distillation, i.e., a conventional method that
separates compounds based on differences in their boiling
points.
     Elsewhere, the specification repeatedly and consist-
ently uses the term “fractionation,” whether modified by
an adjective or not, in connection with temperature or
boiling points. See, e.g., id. col. 2 ll. 58–59 (“naphtha
resulting from crude oil fractionation has a boiling range
of 100 to 350º F”); id. col. 2 ll. 62–63 (“naphtha undergoes
further fractionation to separate a cut point of below
200º F, light naphtha”); id. fig.1 & col. 5 ll. 9–14 (describ-
ing a “Fractionation & PSA Refrigeration” unit in Figure
1, where ethylene, a more volatile compound, is recovered
by “refrigerated fractionation,” and propylene and C4 mix,
less volatile compounds, are each recovered by “warm
fractionation”); id. col. 5 ll. 24–34 (stating that the hydro-
treated pyrolysis gasoline undergoes “fractionation” for
benzene recovery in two distillation columns). Although
the specification uses the word “distillation” only in some
instances, id. col. 2 ll. 23, 60; id. col. 3, ll. 10–11; id. col. 8,
ll. 12–13, the repeated and consistent references to “frac-
tionation” in the context of boiling-point-based separation
indicate that the patentee uses “fractionation” to refer to
distillation specifically, not to generic “separation.”
     Importantly, the patentee distinguished conventional
extraction from fractionation in the specification, indicat-
ing that “fractionation” does not include conventional
extraction.     After identifying the azeotrope problem
encountered by “conventional fractionation,” id. col. 2
ll. 17–20, the specification explains that “[t]he conven-
tional method of benzene purification and separation from
the above azeotropes is by aromatic extraction or extrac-
tive distillation processes, such as [the] Sulfolane [pro-
cess],” id. col. 2 ll. 21–25 (emphases added), which
produces >99.9% pure benzene, id. col. 2 l. 28. Thus,
according to the patentee, conventional extraction and
DAVID NETZER v. SHELL OIL COMPANY                         11



conventional fractionation are different methods. Unlike
conventional fractionation, conventional extraction—
which includes the Sulfolane process—can successfully
remove non-aromatic hydrocarbon azeotropes to produce
highly pure benzene. The Sulfolane process is therefore
conventional extraction, not “conventional fractionation.”
The Sulfolane process was developed by Shell in the
1960s; it is a conventional method of separation. If one
were to adopt Netzer’s proposed construction that “frac-
tionation” means separation by any method, then “con-
ventional fractionation” would mean separation by any
conventional method, which would encompass the Sul-
folane process. That interpretation would be contrary to
the specification.
     Furthermore, as shown by the intrinsic record, the pa-
tentee clearly disclaimed conventional extraction, charac-
terizing it as expensive and not required due to a shift in
market demand, and distinguishing it from the “present
invention.” Id. col. 2 ll. 25–28, 33–37, 44–48, 51–55. The
specification explains that there had been a strong mar-
ket demand for “benzene of nitration grade, about 99.9 wt
%,” id. col. 1 l. 54, but that such high purity benzene was
no longer required in some circumstances; rather, ben-
zene products from the “present invention” containing
non-aromatic impurities can be used in its place. Id. col. 2
ll. 46–48 (“the assumed non-aromatic impurities in the
benzene, resulting from the application of the present
invention” (emphasis added)); id. col. 2 ll. 54–55 (“This
market shift is the major driving force behind the present
invention.” (emphasis added)). Likewise, 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.” J.A. 261, 880 (emphases
added).
   Those clear statements indicate that the inventor con-
templated the claimed invention to be different from
12                       DAVID NETZER v. SHELL OIL COMPANY




conventional extraction, which produces highly pure,
nitration-grade 99.9% benzene. If “fractionation” were to
include conventional extraction, then the claimed process
would yield 99.9% pure benzene and there would not be
significant “non-aromatic impurities . . . resulting from
the application of the present invention.” ’496 patent col.
2 ll. 46–48; see also id. col. 3 l. 58, col. 4 ll. 26–30 (“In
accordance with the inventive method,” “fractionation”
produces “close to 98 wt % benzene.”).
    To be clear, we only conclude that the patentee dis-
claimed conventional extraction, such as the Sulfolane
process. We recognize that the claim language only sets a
lower limit on the purity of the benzene product, and thus
does not preclude other unconventional distillation meth-
ods that are capable of producing highly pure benzene.
But in view of the disclaimer of conventional extraction in
the publicly available intrinsic record, Netzer cannot now
attempt to recapture the disclaimed subject matter.
     Netzer also argues that construing “fractionating” as
distillation would improperly exclude the preferred em-
bodiment disclosed in Figure 1 of the ’496 patent. We
disagree. In that disclosed embodiment, the pyrolysis
gasoline is passed through a hydrotreater, and the result-
ing “hydrotreated pyrolysis gasoline” is then passed
through two distillation columns to produce a benzene
product with 98% to 99% purity. Id. fig.1 & col. 5 ll. 21–
26, 48–51. Contrary to Netzer’s argument, the hydro-
treater embodiment does not compel a different meaning
of “fractionating.” The disclosed embodiment merely adds
a hydrotreating step—a step that does not separate the
individual components of the pyrolysis gasoline from each
other, but rather hydrogenates the olefins in that mix-
ture—before the fractionating step; it does not require the
construction of “fractionating” to include hydrotreating, or
any process other than distillation. Notably, dependent
claim 19 is directed to a process “further comprising” a
DAVID NETZER v. SHELL OIL COMPANY                           13



hydrotreating step, id. col. 8 ll. 33–35, thus showing that
hydrotreating is not part of the fractionating step.
    Rather, the intrinsic record suggests that the patentee
referred to the hydrotreated pyrolysis gasoline as a type
of pyrolysis gasoline: the language of claim 1 defines
“pyrolysis gasoline” as “comprising olefins, di-olefins and
benzene,” id. col. 7 ll. 28–29, and the specification refers
to the product from the hydrotreater as the “hydrotreated
pyrolysis gasoline,” id. col. 5 l. 25, which is then distilled
twice to form benzene with 98% to 99% purity. According-
ly, under the proper construction of “fractionating,” the
disclosed embodiment is within the scope of the claims.
     Netzer primarily relies on two pieces of intrinsic evi-
dence, but neither supports its proposed construction.
First, Netzer notes that dependent claim 11 recites “con-
ventional fractionation in a distillation column.” Id. col. 8
ll. 9–13. Netzer argues that if fractionation means distil-
lation, then there would be no need to state “fractionation
in a distillation column.” We find that argument unavail-
ing. The quoted phrase merely requires that the fraction-
ation, or distillation, occur in a distillation column as
opposed to in another device. Such specific, clarifying
language does not change the meaning of fractionation.
      Second, Netzer relies on a passage in the specifica-
tion, which states that: “Fractionation and production of
benzene with over 75 wt % purity from reformer reactor
effluent by conventional distillation may become difficult
. . . .” Id. col. 3 ll. 9–11. Netzer again argues that if
fractionation means distillation, then it does not make
sense to say “fractionation . . . by conventional distilla-
tion.” We disagree. Netzer has not quoted the full sen-
tence. The omitted portion of the quoted sentence reads:
“. . . because of the azeotrope forming characteristics of
compounds such as dimethylpentanes, cyclohexane and
methyl-cyclopentane.” Id. col. 3 ll. 11–13. Thus, that full
sentence explains that the listed azeotropes make conven-
14                       DAVID NETZER v. SHELL OIL COMPANY




tional fractionation, i.e., conventional distillation, diffi-
cult. To avoid that problem, one may resort to unconven-
tional fractionation techniques, such as the claimed
process of cracking the C6–C7 azeotropes to convert them
to shorter chain and more volatile hydrocarbons before
fractionation. Thus, the quoted sentence is entirely
consistent with, and indeed supports, our construction of
“fractionating.”
    Accordingly, the intrinsic evidence here points in only
one direction, and requires that “fractionating” in this
patent be construed as separating compounds based on
differences in boiling points. The parties cite conflicting
extrinsic evidence, which does not compel a different
construction. As we have explained, extrinsic evidence
may not be used to contradict claim meaning that is
unambiguous in light of the intrinsic record. Summit 6,
LLC v. Samsung Elecs. Co., 802 F.3d 1283, 1290 (Fed. Cir.
2015).
    We therefore conclude that “fractionating” in the pre-
sent patent means separating compounds based on differ-
ences in boiling points, which excludes conventional
extraction methods, such as the Sulfolane process.
                     B. Infringement
    Netzer also argues that the district court erred in
granting summary judgment of noninfringement. Accord-
ing to Netzer, under its proposed construction, Shell’s
accused process satisfies the fractionating limitation
because Shell separates 99.9% pure benzene from pyroly-
sis gasoline. Even under Shell’s proposed construction,
Netzer contends, Shell still literally infringes the ’496
patent because it directs its pyrolysis gasoline through a
series of process units, some of which are distillation
columns, and forms 99.9% pure benzene in the end. It is
irrelevant that the mixture also passes through an extrac-
tor as part of that process, according to Netzer, because
adding an extra step to an otherwise infringing process
DAVID NETZER v. SHELL OIL COMPANY                           15



does not defeat a finding of infringement. Netzer addi-
tionally argues that the district court erred in finding
Netzer barred from relying on the doctrine of equivalents
to prove infringement, and that the accused process
satisfies the function-way-result test as to the “fractionat-
ing” limitation.
     Shell responds that, under the proper construction of
“fractionating,” i.e., distillation, or separating compounds
based on differences in boiling points, Shell does not
infringe the ’496 patent because it uses its own Sulfolane
process, which uses extraction, not distillation, to form
>80% pure benzene. More specifically, Shell explains that
its pyrolysis gasoline is refined in multiple steps to yield a
mixture containing about 57% benzene, far below the 80%
required by the claims; and Shell then uses the Sulfolane
process to remove non-aromatic impurities in that mix-
ture to produce 99.9% pure benzene. Shell also responds
that Netzer is barred from asserting infringement under
the doctrine of equivalents because the patentee dis-
claimed the Sulfolane process. Even if Netzer is not
barred, Shell argues, the Sulfolane process does not purify
benzene in substantially the same way as “fractionating.”
    We agree with Shell that the district court did not err
in granting summary judgment of noninfringement.
Shell’s process does not literally meet the fractionating
limitation. Shell relies on conventional extraction—more
specifically, its own Sulfolane process—to refine a mixture
containing about 57% benzene to a benzene product of
greater than 80% purity. As we have explained, “frac-
tionating” means distillation; it does not include conven-
tional extraction. Moreover, the earlier steps of the Shell
process only refine pyrolysis gasoline to produce a 57%
pure benzene mixture, which does not satisfy the limita-
tion “to form a purified benzene product comprising at
least about 80 wt % benzene.”
16                       DAVID NETZER v. SHELL OIL COMPANY




    It is true that a method claim with the word “compris-
ing” appearing at the beginning generally allows for
additional, unclaimed steps in the accused process, but
each claimed step must nevertheless be performed as
written. Dippin’ Dots, Inc. v. Mosey, 476 F.3d 1337, 1343
(Fed. Cir. 2007) (“[The] enumerated steps must . . . all be
practiced as recited in the claim for a process to infringe.
The presumption raised by the term ‘comprising’ does not
reach into each of the six steps to render every word and
phrase therein open-ended . . . .”). Netzer’s infringement
theory requires rewriting the claimed step to read “frac-
tionating the pyrolysis gasoline [and] form[ing] a purified
benzene product” rather than “fractionating the pyrolysis
gasoline to form a purified benzene product,” as the claim
is written.
    We are also unpersuaded by Netzer’s argument ana-
logizing the accused process to the preferred embodiment
of the ’496 patent, as both process the pyrolysis gasoline
through multiple steps and generate >80% pure benzene
in the end. As we have explained, hydrotreating is not
part of the fractionating step. The hydrotreating step in
the preferred embodiment merely produces a hydrotreat-
ed pyrolysis gasoline; it is not a step that separates the
individual components of the pyrolysis gasoline. In the
preferred embodiment, the hydrotreated pyrolysis gaso-
line is distilled twice to form >80% benzene. In contrast,
nothing in the Shell process distills pyrolysis gasoline “to
form” >80% benzene.
     Moreover, as indicated supra, the patentee disclaimed
conventional extraction, including the Sulfolane process.
Netzer cannot now assert that the claimed fractionating
step is literally infringed by the Sulfolane process. Like-
wise, Netzer cannot show infringement under the doctrine
of equivalents. The disclaimer of the Sulfolane process for
literal infringement applies equally to infringement under
the doctrine of equivalents. SciMed Life Sys., Inc. v.
DAVID NETZER v. SHELL OIL COMPANY                        17



Advanced Cardiovascular Sys., Inc., 242 F.3d 1337, 1347
(Fed. Cir. 2001).
     We agree with Shell, moreover, that no reasonable ju-
ry would find that the accused process performs substan-
tially the same function in substantially the same way to
obtain substantially the same result. Warner-Jenkinson
Co. v. Hilton Davis Chem. Co., 520 U.S. 17, 38–40 (1997).
Shell’s Sulfolane process does not purify benzene to >80%
purity in substantially the same way as the claimed
process because almost all of the purification in the Sul-
folane process is done through extraction, i.e., separating
compounds based on solubility differences, which is
substantially different from the claimed process of sepa-
rating compounds based on differences in boiling points.
Drawing all justifiable inferences in Netzer’s favor, we
agree with Shell that Netzer cannot establish infringe-
ment under the doctrine of equivalents in light of the
substantial difference between the claimed process and
the accused process.
    We therefore conclude that the district court did not
err in granting summary judgment of noninfringement,
either literally or under the doctrine of equivalents.
                       CONCLUSION
     We have considered the remaining arguments and
find them unpersuasive. For the foregoing reasons, we
affirm the district court’s summary judgment of non-
infringement.
                      AFFIRMED
