INGEVITY SOUTH CAROLINA, LLC, EXHIBIT 2002
`BASF Corporation v. Ingevity South Carolina, LLC
`IPR2019-00202
`Page 1 of 141
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`Page 2 of 141
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`SEARCH
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`'- SEARCH NOTES
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`Page 3 of 141
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`ISSUE SLIP, STAPLE AREA for additional cross-references
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`‘
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`ISSUING CLASSIFICATION
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`‘
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`IORIGINAL
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`INTERNATIONAL
`CLASSIFICATION
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`CROSS REFERENCE S
`SUBCLASS ONE SUBCLASS PER BLOCK
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`-l------
`IIII_T‘____
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`INDEX OF CLAIMS
`.. Canceled
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`Page 4 of 141
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`RESPONSE »
`
`‘ QUALITY CHECK
`L SCANNING
`~—
`5 FORMALITY REVIE
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`
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`Page 5 of 141
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`Examiner]
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`j FEE DETERMINATION
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`Page 5 of 141
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`us. DEPARTMENT OF COMMERCE
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`PATENT AND TRADEMARK OFFICE
`FEE RECORD SHEET
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`00000014‘101'00362
`740.com
`130.0009“
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`03/233’3008 EHRILEI
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`4
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`Page 6 of 141
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`*BIBDATASHEET
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`Bib Date Sheet
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`‘. TI“
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`CONFIRMATION No. 3399
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`‘Wes‘tvaco Corporation
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`9/9/02 1:431 PM
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`Page 7 of 141
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`FORM PTO—1082
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`Case Docket No. CHR 2001-79
`
`EXPRESS MAIL NO.
`
`
`
`
`L.=PATENT APPLICATION TRANSMITTAL LETTER
`
`‘gTo:
`9
`
`Box Patent Application
`Assistant Commissioner for Patents
`
`Washington, DC
`
`20231
`
`_
` EK902687082US
`
`Transmitted herewith for filing under 35 USC 111 and 37 CFR 1.53
`is the original
`(nonprovisional) patent application of
`
`
`Inventor(s): Laurence H. Hiltzik, Jacek Z. Jagiello,
`
`Edward D. Tolles, and Roger S. Williams
`
`
`Entitled: METHOD FOR REDUCING EMISSIONS FROM
`
`EVAPORATIVE EMISSIONS CONTROL SYSTEMS
`Enclosed are:
`
`
`
`
`
`XXX
`XXX
`XXX /
`”
`
`XXX
`
`18
`5
`3
`
`pages of specification.
`pages of claims.
`'
`sheets of drawings.
`formal”
`informal
`
`3
`
`.
`
`page(s) Abstract..V
`1
`‘
`Executed declaration or oath of the inventors.
`
`An assignment of the inventiOn to: Westvaco Corporation,
`Westvaco Corporate Center,
`1 High Ridge Park, Stamford,
`Connecticut 06905, a corporation of the State of Delaware.
`A separate cover sheet for Assignment
`(Document) accompanying new patent
`application is also attached.
`A certified copy of a
`application.
`Associate power of attorney.
`,_
`A verified statement to establish smallentity status under
`37 CFR 1. 9 and 1. 27.
`
`Information disclosure statement.
`Preliminary amendment
`Other:
`
`.
`
`'
`
`.
`{
`
`‘
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`3
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`E
`
`CLAIMS AS FILED ,
`NUMBER FILED NUMBER EXTRA R*RATE
`
`
`FEE
`
`BASIC FEE
`
`TOTAL CLAIMS
`
`
`
`30 — 20 =
`
`* 10
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`x
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`18.00
`
`'180.00
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`s 740.00
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`INDEPENDENT CLAIMS
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`*NUMBER EXTRA MUST BE ZERO ORwLARGER
`TOTAL
`ASSIGNMENT RECORDATION FEE
`TOTAL
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`‘
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`$ 920.00
`$
`$ 920.00
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`Page 8 of 141
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`Page 8 of 141
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`
`“‘2
`
`Case Docket No. CHR 2001—79
`
`If applicant has small entity status under
`37 CFR 1.9
`and 1.27,
`then divide total fee
`by 2, and enter amount here.
`
`SMALL ENTITY TOTAL
`
`$
`
`XXX A check in the amount of $ 920.00
`application filing fee.
`
`is enclosed to cover the
`
`A check in the amount of $.
`Assignment recordation fee.
`
`is enclosed to cover the
`
`XXX The Commissioner is hereby authorized to charge or credit
`Deposit Account No.
`23—1160
`as described below.
`I have
`enclosed a duplicate copy of this sheet.
`
`Charge the amount of $
`
`w“
`
`»as filing fee.
`
`
`
`
`
`5
`
`XXX Credit any overpayment.
`
`XXX Charge any additional filing fees required under 37 CFR
`' 1.16 and 1.17.
`
`Charge the issue fee Set in 37 CFR 1.18 at the mailing
`'of the Notice of Allowance, pursuant to 37 CPR 1.311(b).
`
`
` Terr B. McDaniel, Re is. No. 28,444
`
`March 18, 2002
`Date
`1
`
`Westvaco Corporation
`5255 Virginia Avenue
`P. O. BOX 118005
`Charleston,
`SC“ 29423—8005
`
`.
`
`TelephOne:
`
`(843) 746—8490
`
`
`
`
`
`
`
`Page 9 of 141
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`EXPRESS MAIL NO. EK90268‘7082US
`
`Case Docket No. CHR 2001—79
`
`CERTIFICATE UNDER/37 C.F.R. 1.10(a)
`
`I hereby certify that this correspondence is being deposited with the United States Postal
`
`
`
`3 Service as Express Mail in an envelope addressed to the Assistant Commissioner for Patents,
`
`Washington, D. C. 20231, on‘ March 18 2002
`
`.
`
`
`
`Attornexfor the Applicants
`Registration No. 28,444
`
`Page 10 of 141
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`Jr
`
`I“
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`Ca“ Docket No. CHR 2001—79
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`4i
`
`Abfivmcsr
`
`
`
`Disclosed is a method for sharply reducing diurnal breathing loss emissions from
`
`automotive evaporative emissions control systems by providing multiple layers, or stages, of
`
`adsorbents. On the fuel source-side of an emissions control system canister, high working
`
`capacity carbons are preferred in, a first canister (adsorb) region. In subseduent canister
`
`region(s) on the vent—side, the preferred adsorbent should exhibit a flat or flattened adsorption
`
`isotherm on a volumetric basis and relatively lower capacity for high concentration vapors as
`
`compared with the fuel scurce—side adsorbent. Multiple approaches are described for attaining
`
`the preferred properties for the vent—side canister region: One approach is to use a filler and/or
`
` improved combination of high working capacity carbons on the fuel source—side and preferred
`
`voidages as a volumetric diluent for flattening an adsorption isotherm. Another approach is to
`
`employ an adsorbent with thedesired adsorption isotherm properties and to process it into an
`
`appropriate shape or form without necessarily requiring any special provision for dilution. The
`
`lower working capacity adsorbent on the vent—side provides substantially lower diurnal
`
`breathing emissions Without a significant loss in working capacity or increase in flow restriction
`
`compared with known adsorbents used in canister configurations for automotive emissions
`
`control systems.
`
`WMWflWWWKWWWWIWW’.“WMUWWAMMWflWKWKWWIW;WWmmMrmn-Imnwxmmvmm\mwmxvr
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`Wmn-Mimwlmmmmwwa «cud.
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`Care-docket No. CHR 2001—79
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`IN THE UNITED STATES PATENT AND TRADEMARK OFFICE
`
`Patent Application for
`
`METHOD FOR REDUCING EMISSIONS
`
`filAFROM EVAPORATIVEEMISSIONS CONTROL SYSTEMS
`,9»?
`
`BACKGROUND OF THE INVENTION
`
`1. Field of the Invention
`
`
`
`This invention relates to a method for reducing emissions from evaporative control
`
`systems including activated carbon particulate—filled canisters and adsorptive monolith~
`
`containing canisters,"Which‘fr’ionoliths include activated carbon, and to, using said adsorbing
`
`canisters to remove volatile organic compounds, and other chemical agents from fluid streams.
`More particularly, this invention relates to using said vapor—adsorbing materials; in hydrocarbon
`
`fuel consuming engines,
`
`._
`
`
`2. Description of Related Art {Including Information Disclosed Under 37 CFR 1.97
`and 37 CFR1.98)
`
`(a)
`
`Standard Working Capacity Adsoprbents
`
`Evaporation of gasoline from motor vehicle fuel systems is a major potential source of
`
`hydrocarbon air pollution. The automotive industry is challenged tO design engine components
`
`and systems to contain, as much as possible, the almost one billion gallons of gasoline
`
`evaporated from fuel systems each year in the United States alone. Such emissions can be
`
`controlled by canister systems that employ activated carbon to\adsorb and hold the vapor that
`
`evaporates. Under certain modes of engine operation, the adsorbed hydrocarbon vapor is
`periodically removed from the carbon by’ drawing airthrough the canister and burning the
`
`desorbed vapor in the engine. The regenerated carbon is then ready to adsorb additional vapor. ,
`
`Under EPA mandate, such control systems have been employed in the US. for about 30 years,
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`
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`‘ caS'w'ngCket N0. CHR 2001—79
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`and during that time government regulations have gradually reduced the allowable emission
`
`_’ levels for these systems. In response, improvements in the control systems have been largely
`
`L focused on improving the capacity of the activated carbon to hold hydrocarbon vapor. For
`
`example, current canister systems, containing activated carbon of uniform capacity, are readily
`capable of capturing and releasing 100 grams of vapor during adsorption and air purge
`
`regeneration cycling. These canister systems also must have low flow restrictions in order to
`
`accommodate the bulk flow of displaced air and hydrocarbon vapor from the fuel tank during
`
`refueling. Improvements in activated carbons for automotive emission control systems are
`
`‘ disclosed in U. S. Patent Nos.: 4,677,086; 5,204,310; 5,206,207; 5,250,491; 5,276,000;
`
`5,304,527; 5,324,703; 5,416,056; 5,538,932; 5,691,270; 5,736,481; 5,736,485; 5,863,858;
`
`5,914,294; 6,136,075; 6,171,373;6,284,705.
`
`A typical canister employed in a state of the art auto emission controlsystem is shown
`
`in Figure 1. Canister 1 includes support screen 2,2dividing wall 3, a vent port 4 to the
`
`atmosphere (for when the engine is off), a vapor source connection 5 (from the fuel‘tank), a
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`vacuum purge connection 6(for When the engine is running), and adsorbent material fill 7.
`
`I Other basic auto emission control system canisters are disclosed in U. SLPatent N03.:
`
`5,456,236; 5,456,237; 5,460,136; and 5,477,836.
`
`Typical carbons for evaporative emission canisters are characterized by standard
`
`measurements of bed packing density (“apparent density,” g/mL), equilibrium saturation
`capacity for 100% butane vapor (“butane-activity,” g/1,00gecarbon), and purgeability (“butane
`
`ratio”), specifically, the proportion of adsorbed butane from the saturation step which can be
`
`
`
`'
`
`recovered from the carbon by an air purge step. The multiplicative product of these three
`
`properties yields a measure of; the carbon’s effective butane “working capacity” (“BWC”, g/dL),
`
`
`
`
`
`
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`Caseréocket No. CHR 2001-79
`
`measured by ASTM’D5228~92, which has been established in the art as a good predictor of the
`
`canister working capacity for gasoline vapors. Carbons that excel for this application haVe high
`
`BWC, typically 9 to 15+ g/dL BWC, as a result of high saturation capacities on» a volumetric—
`
`basis for butane (the product of density and butane activity), and high butane ratios ($0.85). In
`terms of isothermal equilibrium adsorption capacities across all vapor concentrations, these
`
`carbons characteristically have high incremental capacity as a function of increased vapor
`
`concentration (i.e., isotherm curved upward on a semi—log graph). This isotherm upward curve
`
`reflects the high working capacity performance feature of these‘carbons, in that gasoline vapors
`
`are adsorbed in high quantity at high concentrations but readily released in high concentration
`
`to an air purge stream.
`
`In addition, these carbons tend to be granular (somewhat irregularly
`
`shaped) or cylindrical pellet, typically of a size just about 1-3 mm in diameter. It has been
`
`.
`
`found that somewhat larger sizes hinder diffusional transport of vapors into and out of the
`
`carbon particle during dynamic adsOrb and purge cycles. On the other hand, somewhat smaller
`
`
`size particles have unacceptably high flow restriction for displaced air and hydrocarbon vapors
`
`during refueling.
`
`(b)
`
`Diurnal Breathing Loss (DBL) Requirements
`
`Recently, regulations have been promulgated that require a change in the approach with
`respect to the way in which vapors must be controlled. Allowable emission levels from
`
`canisters would be reduced to such low levels that the primary source of emitted vapor, the fuel
`
`tank, is no longer the primary concern, as current conventional evaporative emission control
`
`appears to have achieved a high efficiency of removal. Rather, the concern now is actually the
`
`hydrocarbon left on the carbon adsorbent itself as a residual “heel” after the regeneration
`
`(purge) step. Such emissions typically occur when a vehicle has been parked and subjected to
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`
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`cab‘;'*1::)ocket No. CHR 2001—79
`
`diurnal temperature changes over a period of several days, commonly dalled “diurnal breathing
`
`_ losses.” Now, the California Low Emission Vehicle Regulation makes it desirable for these
`
`diurnal breathing loss (DBL) emissions from the canister system to be below 10 mg (“PZEV”)
`
`_
`
`foria number of vehicles beginning with the 2003 model year and below 50 mg, typically below
`
`£0 mg, (“LEV—II”) for a larger number of vehicles beginning with the 2004 model year.
`
`(“PZEV” and “LEV-II” are criteria of the California Low Emission Vehicle Regulation.)
`
`While standard carbons used in the commercial canisters excel in terms of working
`
`Micapacity, these carbons are unable to meet DBL emission targets under normal canister
`
`operation. Furthermore, none of the standard measures of working capacity properties correlate
`
`with DBL emission performance. Nonetheless, one option for meeting emission targets is to
`
`significantly increase the volume of purge gas during regeneration in order to reduce the
`
`amount of residual hydrocarbon heel in the carbon bed and thereby reduce subsequent
`
`emissions. This strategy, however, has the drawback of complicating management of the
`
`fuel/air mixture to the engine during purge regeneration and tends to adversely affect tailpipe
`
`emissions, i.e., moving or redefining the problem rather than solving it. (See U. S. Patent No.
`
`‘
`-
`4,894,072.)
`Another option is to design the carbon bed so that there is a relatively low cross-
`
`sectional area on the vent—side of the canister system (the first portion of the bed to encounter
`
`purge air),either by~redesign of the existing canisterdimensions Or by the installation of a
`
`supplemental, auxiliary vent—side canister of appropriate dimensions. This alternative has the
`
`effeCt of locally reducing residual hydrocarbon heel by increasing the intensity of purge for that
`
`vent—side portion of the bed, thereby improving its ability to retain vapors that would otherwise ,
`
`be emitted from the canister system under diurnal breathing conditions. The drawback is that
`
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`Case—riocket No. CHR 2001-79
`
`there isa useful limit to which a portion of the bed canvbe elongated at reduced cross-sectional
`
`~
`
`area without otherwise incun‘ing excessive flow restriction by the canister system. In practice,
`
`this limit does not allow employing a sufficiently narrowed and elongated geometry to meet
`
`emission targets. (See U. S. Patent No. 5,957,114.)
`
`Another option for increasing the purge efficiency of a fuel vapor/air mixture fraction
`
`adsorbed in the pores of the adsorbent material is suggested by the teachings of U. S. Patent
`
`Nos. 6,098,601 and 6,279,548 by providing a heating capability internal of the canister, or a
`
`section thereof, either to increase pressure in the vapor storage canister to expel hot vapor
`
`through the vapor/purge conduit back into the fuel tank where it condenses at the lower ambient
`
`temperature therein (’601) or to increase the purging efficiency of hydrocarbons from the heated
`
`adsorbent material and carry the purged fuel vapor to the induction system of an associated
`
`
`engine (’5‘48).1However, this increases the comp‘lexity'of control ystem management, and
`
`there appears some inherent safety Concerns in providing heating internal of a canister for.
`trapping fuel vapors.
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`Thus, an abceptable remedy, which does not have draWbacks as the cited alternative
`approaches, is greatly desired. It is submitted that the invention disclosed and claimed herein
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`provides the desired solution.
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`SUMMARY OF THE INVENTION
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`An invention is disclosed for sharply reducing diurnal breathing loss emissions from
`evaporative emissions canisters by the use of multiple layers, orstages, of adsorbents. On the
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`fuel source-side of the canister, standard high working capacity carbons are preferred. On the
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`vent-side, the preferred adsorbent volume exhibits a flat or flattened adsorbent isotherm on a
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`volumetric basis in addition to certain characteristically desirable adsorptive properties across
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`Cas'e“i50cket No. CHR 2001-79
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`broad vapor concentrations, specifically relatively low incremental capacity at high
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`concentration vapors compared with the fuel source-side adsorbent volume. Two approaches
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`are described for attaining the preferred properties for the vent-side adsorbent volume. One
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`approach is to use a filler and/or bed voidages as a Volumetric diluent for flattening an isotherm.
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`A second approach is to employ an adsorbent with the desired isotherm properties and to
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`process it into an appropriate shape or form without necessarily requiring any special provision ,
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`for dilution. Both such approaches providela substantially lower emissions canister system
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`without a significant loss in working capacity or an increase in flow restriction compared with
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`prior art adsorbents used for automotive emissions control.
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`f.
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`BRIEF DESCRIPTION OF THE DRAWINGS
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`.
`s
`s
`4
`I/
`Figure 1‘ shows, in cross-section, a prior art canister system.
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`Figure 2 shows, in cross—section, one embodimentof the invention canister comprising
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`multiple adsorbents
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`Figure 3/shoWs butane isotherm properties for different activated carbon adsorbents.
`DESCRIPTION OF THE PREFERRED EMBODIMENNS)
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`The disclosed invention relates to the use of multiple beds (or layers, stages, or
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`chambers) of adsorbent materials, which, in combination, significantly reduce DBL emissions
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`while maintaining the high working capacity and low flow restriction properties of the canister
`system.
`(See Figure 2.) These adsorbents include activated carbon from a variety of raw
`materials, including wood, peat, coal, coconut, synthetic or naturalpolymer, and a variety of
`processes, including chemical and/or thermal activation, as well as inorganic adsorbents,
`I
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`.-
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`including moleCular sieves, porous alumina, pillared clays, zeolites, and porous silica, and
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`organic adSOrbents, including porous polymers. The adsorbents may be in granular, spherical,
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`Ca... docket No. CI-lR 2001—79
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`or pelletized cylindrical shapes, 'or may be extruded into special thin—walled cross—sectional
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`»
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`shapes, such as hollow—Cylinder, star, twisted spiral, asterisk, configured ribbons, orother
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`shapes within the technical capabilities of the art. In shaping, inorganic and/or organic binders .
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`may be used. The adsorbents may be formed into admonolith or honeycomb part. The ‘
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`adsorbents may be incorporated into acanister as one or more layers, or separate chambers, or
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`they may be inserted in the fluid stream flow as auxiliary canister beds.
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`One common feature for all of these approaches is to have a vent—side adsorbent with a
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`relatively flat-shaped isotherm. This isotherm shape is important for reasons related to purge
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`efficiency across the adsorbent bed depth. Foran adsorbent with a flat adsorption isotherm, the
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`concentration of hydrocarbon vapor in equilibrium with adsorbed hydrocarbon, by definition,
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`decreases further as the adsorbed hydrocarbon is'removed compared with an adsorbent with a
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`more steeply sloped isotherm. Thus, whenVSuCh' amaterial is employed as an adsorbent volume
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`on the vent-side region of a canister, purgeis able to reduce the vapor concentration in the area
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`of the purge inlet to a very low level. Since it is the vapor near the purge inlet that eventually
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`emerges as bleed, decreasing this concentration reduces thebleed emission level. The degree of
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`removal of adsorbed hydrocarbon during: purge is determined by the difference between the
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`concentration of hydrocarbon picked up in the purge gas and the concentration in equilibrium
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`with the adsorbent at any point in the bed. Thus, adsorbent in the immediate vicinity of the
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`purge inlet will be most thoroughly regenerated. V’At points deeper in the adsorbent bed, less
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`hydrocarbon will be removed because the purge gas will already contain hydrocarbon removed
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`from previous points in the bed. An adsorbent with a flatter adsorption isotherm will give up
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`less vapor into the purge stream and this purge will then be more efficient in reducing vapor
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`concentrations deeper into the bed. Therefore, for a given quantity of purge gas, it will be
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`Casebocket No. CI—IR 2001-79
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`possible to reduce the vapor concentration in a volume of adsorbent with a flat adsorption
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`isotherm to a lower level than the concentrationin the same volume of an adsorbent With a
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`‘ steep adsorption isotherm. Bleed emission from such a volume will therefore be lower when
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`the adsorbent has a flatter adsorption isotherm.
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`A region within a canister containing particulate Orin an adsorbent—containing monolith
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`with the preferred adsorption isotherm properties for achieving low bleed emission levels will,
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`however, have a relatively low adsorption working capacity compared to the activated carbons
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`commonly used in automotive evaporative emission control. For example, the BWC of a low
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`capicity adsorbent will be about 6 g/dL comparedto the 9 g/dL to 15+ g/dL range as used in
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`typical automotive carbons. Therefore, in order to maintain the required hydrocarbon capacity
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`for normal emission control system operation, the low—bleed adsorbent will be used in a vent-
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`side auxiliary region within the’canister or outside the canister in combination with an fuel
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`source—side region containing a volume of the high capacity carbon normally employed. When
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`two different adsorbents are used, for example, system design will involve providing sufficient
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`volume of the high capacity carbon in the main part, or fuel source-side, of an emisssion control
`canister to achieve the desired working capacity, and a suffiCient volume of the low-bleed
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`adsorbent to contain vapor emitted from the main bed to such an extent that such vapor does
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`not materially affect the bleed emissions from the low-bleed adsorbent.
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`In the context of the invention, “monolith” is intended to include foams, woven and
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`non—woven fibers, mats, blocks and bound aggregates of particulates.
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`It is notable that the emission of vapor from the main, high—capacity fuel source-side
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`volume of adsorbent into the auxiliary lower capacity vent—side volume is significantly affected .
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`by the presence of that vent—side volume. During purge, a vent-side adsorbent volume having a
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`flat adsorption isotherm will give up a relatively small hydrocarbon load into the purge gas.
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`~
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`Therefore, the concentration of vapor carried by the purge gas will be low as it emerges from
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`the low—bleed vent—side volume and enters the high-capacity, fuel source—side volume. This
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`allows good regeneration of the high—capacity adsorbent in the vicinity of the junction of the
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`two adsorbent volumes, and helps protect the vent-side volume from emissions from the fuel
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`source—side region of the canister during diurnal breathing flow. Specifically, the greater
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`regeneration efficiency of the fuel source-side volume reduces diurnal emissions by retarding
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`the rate of bulk phase diffusion across the flow length of the canister system. Since bulk phase
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`diffusion is a major mode of vapor transport during diurnal breathing conditions, by reducing
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`the vapor concentration difference across the flow length of the canister system by enhanced
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`regeneration, the redistribution of vapors within the canister system and subsequent emissions
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`into the vent—side volume and out of the vent pokrt‘are reduced.
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`Examples of adsorbents with isotherms having the preferred shape to provide low bleed
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`performance are compared with standard. canister—fill carbons (Westvaco Corporation’s BAX
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`1100 and BAX 1500) in Figure 3. It is important to note that, as shown in this figure, the
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`isotherm properties must be defined in terms of volumetric capacity. ’On this basis, the
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`preferred low—bleed adsorbent portion will have an incremental n-butane capacity of less than
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`about 35 g/liter between 5 and 50 volume percent n-butane vapor concentration.
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`While in some instances, known adsorbents may have the preferred properties for the
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`vent-side, these adSOrbents would not be expected to be useful in an evaporative canister. In
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`some cases, these materials have low purgeability (butane ratio less than 0.85) and low working
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`capacity (BWC less than 9 g/clL) as measured by the standard BWC test for qualifying canister
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`,
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`carbons. Common wisdom and experience in the art associate low butane ratio with high
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`(3a.. docket No. CHR 2001—79
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`residual hydrocarbon heel, which is the potential source for high emissions. Furthermore, low
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`BWC adsorbents were not considered useful for inclusion into a canister system as working
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`capacity for gasoline vapors would be assumed impaired, with no expectation that there would
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`be a utility for reducing emissions. In fact, one preferred embodiment of this invention, lower
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`capacity adsorbents have BWC values preferably below 8 g/dL, which is well below the 9-15+
`g/dL‘BWC level normally deemed suitable for use in evaporative emission control canister
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`systems. The preferred selection of these low BWC materials for inclusion into a canister
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`system as a vent—side layer to produce low emissions was only realized once the dynamics
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`within the adsorbent bed were realized (i.e., the significance of low residual vapor
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`concentration within the vent—side bed volume and the interactive effect that the vent—side bed
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`volume has on the distribution and diffusion of vapor across the entire canister system during
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`the diurnal breathing loss period).
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`Therefore, it has been found that the preferred vent—side adsorbent properties, in
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`addition to a relatively low BWC, includes butane ratios between 0.40 and 0.98, which in total
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`are substantially different properties compared with adsorbents previously conceived as useful
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`for these canister systems.
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`The proposed alternative approaches described above are shown to be effective in
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`canister bleed emission control in the following examples. One approach for preparing the
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`vent—side adsorbent is to volumetrically dilute a high working capacity adsorbent so that its
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`resulting isotherm is flattened on a volumetric basis. A second approach is to begin with an
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`adsorbent that has the desired adsorption capacity and flat isotherm shape and process it into a
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`shape or form, such as a pellet or honeycomb.
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`10‘
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`//
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`case Docket No. CHR 2001~79
`A particular preferred embodiment for a canister with multiple adsorbents is shown in
`Figure 2. Figure 2 shows a canister system comprising a primary canister body 1, a support
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`screen 2, a dividing wall 3, a Vent port 4 to the atmosphere, a vapor source connection 5, a
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`vacuum purge connection 6, a fuel source—side-region 7, vent—side canister regions 8 — 11" of
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`varying low-capacities, supplemental canister body 12, and connecting hose 13 permitting fluid
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`stream flow from the primary canister body 1 to the supplemental canister body 12. Additional
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`embodiments, as discussed above, are also envisioned to be within the scope of the subject of
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`the invention.
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`The desired results for the subject matter of the invention can be attained with a single
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`vent-side uniform lower capacity adsorbent material as the subsequent adsorbent material. The
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`option of multiples of lower capacity adsorbents with the desirable adsorptive properties across
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`broad Vapor concentrations is demonstrated merely as one embodiment.
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`The measures for gasoline working capacity (GWC) and emissions in the Table were
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`derived from the Westvaco DBL test that uses a 2.1L canister. The pellet examples were tested
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`as a 300 mL vent~side layer within the canister, with the 1800 mL of BAX 1500 pellets as the
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`remaining canister fill. The honeycomb was tested as an auxiliary bed canister that was placed
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`in-line with the 2.1L main canister of BAX 1500 pellets. For all examples, the canister system
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`was uniformly first preconditioned by repetitive cycling of gasoline vapor adsorption and air
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`purge (400 bed volumes air). This cycling generated the GWC value. Butane emissions were
`subsequently measUred after a butane adsorption and an air purge step, specifically during a
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`diurnal breathing loss period when the canister system was attached to a temperature-cycled
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`fuel tank. The reported value is the 2nd day DBL emissions during an 11—hour period when the ,
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`fuel tank was warmed and vapor-laden air was vented to the canister system and exhausted
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`11
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`(Z
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`from the vent~side adsorbent where the emissions were measured. The procedure employed for
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`measuring DBL emissions has been described in SAE Technical Paper 200] -01 —0733, titled
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`“Impact and Control of Canister Bleed Emissions,” by R. S. Williams and C. R. Clontz.
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`Example 1: Microsphere Filler Pellets. These 2 mm pellets are an example of the
`_ volumetric dilution method by adding-a solid filler to the extrusion formulation. The pellets
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`were prepared from an extrusion blend consisting of Westvaco SA—lSOO powder (12.8 wt%),
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`solid glass microsphere filler (79.7 wt% PQ Corporation A3000), bentonite clay (7.2 wt%), and
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`phosphoric acid (0.3 wt%). The pellets were tumbled for four minutes, dried overnight at
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`105°C, and subsequently heat—treated in steam at 650°C for 15 minutes. An appropriate non~
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`adsorbing filler reduces adsorption capacities across all vapor concentrations, resulting in a
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`flattened adsorption isotherm (“Example 1” in Figure 3). Alternative methods for diluting the
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`vent-side region are to co-mix adsorbent granules or pellets with inert filler particles of similar
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`size, to form the extrusion paste into high voidage shapes such as hollow cylinders, asterisks,
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`stars, or twisted, bent, or spiral ribbon pieces, or to place multiple thin layers of non-adsorbing
`particles or porous mats (e.g., foam), or simply trapped air space between layers of adsorbent.
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`Example 2: Ceramic—Bound Honeycomb. The 200 cpsi (cells per square inch) carbon—
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`containing honeycomb is another example of the volumetric dilution method. The honeycomb
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`in the Table was prepared according to the method described in US. Patent No. 5,9