(12)united states patent us 9,289,741 b2availabletechnologies.pnnl.gov/media/418_52201695044.pdf ·...

$: (12)United States Patent US 9,289,741 B2availabletechnologies.pnnl.gov/media/418_52201695044.pdf · (12)United States Patent TeGrotenhuis et al. ... 13 0‘ 2 3e 5 WIF {mngminimi}$
(12)United States PatentTeGrotenhuis et al.

US009289741B2

US 9,289,741 B2Mar. 22, 2016

(10) Patent No.:

(45) Date of Patent:

(54)(71)

(72)

(73)

(21)(22)(65)

(60)

(51)

(52)

SUSPENDED-SLURRY REACTOR

Applicants:Ward E. TeGrotenhuis, Kennewick,WA (US); Karim M. Ayman, Richland,WA (US); Paul H. Humble, Kennewick,WA (US); Yong Wang, Richland, WA

(US)Ward E. TeGrotenhuis, Kennewick,WA (US); Karim M. Ayman, Richland,WA (US); Paul H. Humble, Kennewick,WA (US); Yong Wang, Richland, WA

(US)BATTELLE MEMORIALINSTITUTE, Richland, WA (US)

Inventors:

Assignee:

Notice: Subject to any disclaimer, the term of thispatent is extended or adjusted under 35U.S.C. 154(b) by 441 days.

Appl. No.: 13/753,714

Filed: Jan. 30, 2013

Prior Publication Data

US 2013/0197109 A1 Aug. 1,2013

Related U.S. Application Data

Provisional application No. 61/593,486, ■led on Feb.1,2012.

Int. Cl.B01] 8/02 (2006.01)C013 3/26 (2006.01)

(Continued)

U.S.Cl.CPC.. 30118/02(2013.01);30118/009(2013.01);

301110/007(2013.01);301119/0053(2013.01);301119/0093(2013.01);3011

19/249(2013.01);301119/2475(2013.01);301123/42(2013.01);301123/44(2013.01);

301135/002(2013.01);301135/023(2013.01);00133/26(2013.01);C10G2/00

(2013.01);C10G2/342(2013.01);C013

280\

2203/0277(2013.01);C0132203/1064(2013.01);C0132203/1082(2013.01)

(58) Field of Classi■cation SearchCPC ................B01] 8/02; B01] 8/009; B01] 7/00;

B01] 7/02; C01B3/0015; C01B3/26Seeapplication ■le for complete searchhistory.

(56) References Cited

U.S.PATENTDOCUMENTS

5,849,235 A * 12/1998 Sassaetal.................

264/28886,666,909 B1* 12/2003 TeGrotenhuis et a1.

.........95/273

(Continued)

FOREIGN PATENT DOCUMENTS

CAGB

2206626 11/19982059793 A 4/1981

(Continued)

OTHERPUBLICATIONS

International SearchReport/Written Opinion for International Appli-cation No. PCT/US2013/023986, International ■ling date ]an. 31,2013, Date ofmailing Apr. 11, 2013.

(Continued)

Primary Examiner 7 Lessanework Seifu(74) Attorney, Agent, or Firm 7 A. ]. Gokcek

(57) ABSTRACTAn apparatus for generating a large volume of gas from aliquid streamis disclosed. The apparatusincludes a■rstchan-nel through which the liquid stream passes.The apparatusalso includes a layer of catalyst particles suspendedin a solidslurry for generating gas from the liquid stream. The appara-tus further includes a second channel through which a mix-ture of converted liquid and generated gas passes.A heatexchangechannelheatsthe liquid stream.A wicking structurelocated in the second channel separatesthe gas generatedfrom the converted liquid.

17 Claims, 16 Drawing Sheets

3:00240 /

210 270

US 9,289,741 B2Page2

(51) Int.Cl.C10G2/00 (2006.01)B01] 10/00 (2006.01)B01] 19/00 (2006.01)B01] 19/24 (2006.01)B0118/00 (2006.01)B01123/42 (2006.01)B01123/44 (2006.01)B01135/00 (2006.01)B01135/02 (2006.01)

(56) References Cited

U.S. PATENT DOCUMENTS

7,261,961 B2*7,351,395 B17,429,372 B27,485,161 B2*

2010/0217044 A1

8/2007 Kamachi et al...............

429/4164/2008 Pez et al.9/2008 Pez et al.2/2009 Toseland et al.

..................48/61

8/2010 Nomura et al.

FOREIGN PATENT DOCUMENTS

WO 9634686 11/1996WO 2005/000457 A2 1/2005

OTHER PUBLICATIONS

Scherer, G. W. H., et al., Analysis of the SeasonalEnergy Storage ofHydrogen in Liquid Organic Hydrides, International Journal ofHydrogen Energy, 23, l, 1998, 19-25.

Hodoshima, S., et al., Catalytic decalin dehydrogenation/naphtha-

lene hydrogenation pair as a hydrgen source for fuel-cell vehicle,

International Journal of Hydrogen Energy, 28, 2003, 1255-1262.

Kariya, N., et al., Ef■cient evolution of hydrogen from liquid

cycloalkanes over Pt-containing catalysts supported on active car-bons under “wed-dry multiphase conditions”, Applied Catalysis A:

General,233,2002,91-102.Xu, J., et al., Transient ■ow patterns and bubble slug lengths in

parallel microchannels with oxygen gas bubbles produced by cata-lytic chemical reactions, Internation Journal of Heat and Mass Trans-

fer, 50,2007,857-871.Wang, G., et al., Unstable and stable ■ow boiling in parallelmicrochannels and in a single microchannel, International Journal of

Heat and Mass Transfer, 50, 2007, 4297-4310.Yang, J

., et al., High capacity hydrogen storage materials: attributesfor automotive applications and techniques for materials discovery,Chemical Society Reviews, 39, 2010, 656-675.Al-Dahhan, M. H., et al., Reproducible Technique for Packing Labo-ratory-Scale Trickle-Bed Reactors With a Mixture of Catalyst andFines, Ind. Eng. Chem., Res, 34, 1995, 741-747.Losey, M. W., et al., Microfabricated Multiphase Packed-Bed Reac-

tors: Characterization of Mass Transfer and Reactions, Ind. Eng.

Chem.Res.,40, 2001,2555-2562.Ahluwalia, R. K., et al., System Level Analysis of Hydrogen StorageOptions, 2007 DOE Hydrogen Program Review, May 15-18, 2007,Arlington, VA.

* cited by examiner

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US 9,289,741 B21

SUSPENDED-SLURRY REACTOR

CROSS-REFERENCE TO RELATEDAPPLICATIONS

This application claims priority to US. Provisional Appli-cation Ser. No. 61/593,486, ■led Feb. 1, 2012, titled “SUS-PENDED-SLURRY REACTOR CONCEPT,” hereby incor-porated by reference in its entirety for all of its teachings.

STATEMENT REGARDING FEDERALLYSPONSORED RESEARCH OR DEVELOPMENT

The invention was made with Government support underContract DE-AC05-76RL01830, awarded by the US.Department of Energy. The Government has certain rights inthe invention.

TECHNICAL FIELD

This invention relates to heterogeneouschemical reactors.More speci■cally, this invention relates to suspended-slurrychemical reactors for generating a large volume of gasfrom aliquid stream or for producing liquid from a gaseousstream.

BACKGROUND OF THE INVENTION

Systems involving heat or mass transfer are crucial to ourindustrialized society. Examples of such systems include:

power generation, chemical processing systems,and heatingand cooling systems.For more than 100 years, scientists andengineers have endeavored to increase the ef■ciency orreduce the cost of these systems.

Battelle, Paci■cNorthwest National Laboratories, andoth-

ers have been using microtechnology to develop Microsys-tems for carrying out processes that had previously beenconducted using far larger equipment. These systems,whichcontain features of about 1 millimeter (mm) or less, maypotentially changeheat and masstransfer processing in waysanalogousto the changesthat miniaturization havebrought tocomputing. Microsystems can be advantageously used insmall scaleoperations, suchasin vehicles. Microsystems that

can be economically mass-produced can be connectedtogether to accomplish large scale operations.

The production of hydrogen from hydrocarbon fuels, for

usein fuel cells, is oneexample of anapplication that hasbeenproposed for microsystems. Fuel cells are electrochemicaldevices that convert fuel energy directly to electrical energy.For example, in aprocessknown assteamreforming, amicro-system can convert a hydrocarbon fuel (or an alcohol suchasmethanol or ethanol) to hydrogen and carbon monoxide. Thehydrogen is fed to a fuel cell that reacts the hydrogen with

oxygen (from the air) to produce water andanelectric current.The CO could, in a reaction known as the water gas shiftreaction, be reacted with water to produce additional hydro-

gen and carbon dioxide.A second application has been proposed for delivering

hydrogen to fuel cells that involves liquid organic hydrogencarriers (LOHCs). A chemical reactor is operated that

removes molecular hydrogen from a LOHC through one ormore dehydrogenation reactions, and the hydrogen is con-sumed in a fuel cell to produce electricity. The spent dehy-drogenated LOHC is recovered and returned to a centralfacility where reversehydrogenation reactions reload hydro-

gen onto the LOHC. By this process, the LOHC servesas a

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2carrier for delivering hydrogen to fuel cells or other powersystemsin distributed applications, such ason fuel cell pow-ered vehicles.

Despite long and intensive efforts, there remains aneed for

energy ef■cient and cost effective systems for carrying outoperations involving heat or mass transfer. There is also aneed for compact systems or reactor systems for generatinglarge volumes of gasfrom aliquid stream,for producing largevolumes of liquid from a gaseousstream, and for performing

a reaction between a gaseousstream and a liquid stream.

SUMMARY OF THE INVENTION

In one embodiment of the present invention, an apparatusfor generating large volumes of gas from a liquid stream isdisclosed. The apparatus includes a ■rst channel throughwhich the liquid streampasses.The apparatusalso includes alayer of catalyst particles suspended in a solid slurry forgenerating gas from the liquid stream. The apparatusfurtherincludes a second channel through which a mixture of con-verted liquid and generated gaspasses.

In oneembodiment, the apparatusincludes aheatexchangechannel for heating the liquid stream.A wicking structure canbe located in the second channel for separating the gas gen-erated from the converted liquid.

In one embodiment, the liquid is a liquid organic hydrogencarrier and the gas is hydrogen. The catalyst particles com-prise, but are not limited to, Pt/AlZO3 or Pd/AlZO3. The cata-lyst particles are approximately 2 pm or less.

In one embodiment, the solid slurry consists of catalystparticles held together in a solid-like matrix with a polymer.The polymer is, but not limited to, Te■on.

The catalyst particles comprise at least 60% by massof thesolid slurry and more preferably at least 90% by mass of thesolid slurry. In another embodiment, greater than 50% of thecatalyst is accessible relative to 100% catalyst particles.

In one embodiment, the apparatusfurther includes a struc-tural element in the ■rst channel to support the suspendedslurry and to improve heat transfer.

In one embodiment, the suspendedslurry is lessthan about0.5 mm thick. In another embodiment, the suspendedslurry isless than about 0.15 mm thick.

In one embodiment, the suspendedslurry is in a sheetwith

an area to thickness ratio of at least 10 mm. In anotherembodiment, the suspendedslurry is in a sheetwith an areatothickness ratio of at least 1000 mm. In another embodiment,the suspended slurry is in a sheet with an area to thicknessratio of at least 10,000 m.

In another embodiment of the present invention, a methodof generating a large volume of gas from a liquid stream isdisclosed. The method includes passing the liquid streamthrough a ■rst channel; generating gasby passing the liquidstream through a layer of catalyst particles suspended in asolid slurry; and passing a mixture of converted liquid andgenerated gas through a secondchannel.

In another embodiment of the present invention, an appa-ratus for producing liquid from a gaseousstreamis disclosed.The apparatus includes a ■rst channel through which the

gaseousstreampasses.The apparatusalso includes a layer ofcatalyst particles suspendedin a solid slurry for generatingliquid from the gaseous stream. The apparatus furtherincludes a second channel through which a mixture of con-verted gas and generated liquid passes.

In another embodiment of the present invention, a methodof producing liquid from a gaseousstream is disclosed. Themethod includes passing the gaseous stream through a ■rstchannel; generating liquid by passing the gaseous stream

US 9,289,741 B23

through a layer of catalyst particles suspended in a solidslurry; and passing a mixture of converted gasand generatedliquid through a secondchannel.

In another embodiment of the present invention, an appa-ratus for performing areaction between agaseousstreamand

a liquid stream is disclosed. The apparatus includes a ■rstchannel through which the gaseous stream and the liquidstreampasses.The apparatusalso includes a layer of catalystparticles suspendedin a solid slurry for producing a productfrom the gaseousand liquid streams. The apparatus furtherincludes a second channel through which a mixture of the

gaseousand liquid streamspasses.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates morphology of small catalyst particlessuspendedin a solid slurry.

FIG. 2 is a scanning electron micrograph of a suspended-slurry structure with 93.4% by mass of 5 wt % Pt/AlZO3catalyst.

FIG. 3 shows a test cell used for characterizing perfor-

mance of suspended-slurry samples, in accordancewith oneembodiment of the present invention.

FIGS. 4A and 4B show the effects of suspended-slurrythickness (key indicates number of layers by layer thickness)

on the conversion of perhydro-N-ethylcarbazole conversionat 230° C. and 1 atm with 5% Pt/Ale3. Solid lines represent■rst-order reaction kinetics, and kl is the corresponding rateconstant.

FIG. 5 shows the effect of catalyst loading on the conver-sion of perhydro-N-ethylcarbazole conversion at 230° C. and1 atm with 5% Pt/Ale3. The % in the legend refers to thecatalyst weight % in the suspended-slurry.

FIG. 6 shows a comparison of FeCrAlY sintered-■bermesh to suspendedslurry concept. The % in the legend refersto the catalyst weight % in the suspended-slurry or the sin-tered metal.

FIG. 7 illustrates a schematic of the suspended-slurry reac-tor, in accordancewith one embodiment of the present inven-tion.

FIG. 8 is a fabrication drawing of a reactor plate of thesuspended-slurry reactor of FIG. 7, with a side cross-sec-tional view along ‘A-A’ of the reactor, in accordancewith oneembodiment of the present invention.

FIG. 9 is acut-out of the cross-sectional view of the reactorplate of FIG. 8, in accordance with one embodiment of thepresent invention.

FIG. 10 illustrates a suspended-slurry reactor with heattransfer elements attached to both sides, in accordance withanother embodiment of the present invention.

FIG. 11 illustrates a suspended-slurry reactor with tworeactor repeat units stacked together with heat transfer ele-ments on both sidesand amanifold for heating with ahot gas.

FIG. 12 showsthe effect of catalyst dilution and bed diam-eter on NEC conversion in the suspended-slurry reactor ofFIG. 3 at 230° C. and 1 atm with 5 wt % Pt/Ale3.

FIG. 13 showsthe increase in apparent activity when cata-lyst particles are diluted, and the relative importance of inter-particle mass transfer on conversion of NEC in a 4.2 mmdiameter suspended-slurry reactor of FIG. 3 at 230° C. and 1atm with 5 wt % Pt/Ale3.

FIG. 14 showsmeasured data for the amount of hydrogenproduced from the reactor of FIG. 11 as a function of oper-ating temperature and perhydro-NEC feed ■ow rate, as well

as curves ■tted to the data for 200° C., 220° C., and 240° C.FIG. 15 shows the ■ttedcurves from FIG. 14 converted to

percent conversion of the carbazole (sameashydrogen ■eld)

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4basedon the feed ■ow rate of perhydro-NEC. Also shown isthe residence time (dashed line) calculated from the internalvoid volume and feed ■ow rate.

FIG. 16 illustrates an exploded assembly view of the sus-pended-slurry reactor of FIG. 10, in accordance with oneembodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERREDEMBODIMENTS

Embodiments of the present invention include, but are notlimited to, the following: an apparatus and method of gener-ating a large volume of gasfrom a liquid stream; an apparatusand method of producing liquid from a gaseousstream; and

an apparatusand method of performing a reaction between agaseousstream and a liquid stream.

The suspended-slurry reactor, in certain embodiments,

usesvery small catalyst particlesgdiameter on the order ofabout 1 umito decrease internal mass transfer resistance.Pressure drop is a signi■cant challenge in packed beds ofmicron-sized particles, so one objective is to immobilize theparticles in a thin structure that is less than about 1mm thickand that has ahigher void fraction than a packed bed in orderto reduce pressure drop. The small particles and inherenttortuosity of the structure reduces external mass transferresistance by reducing the mass transfer boundary layerthickness around the particles. FIG. 1 illustrates one embodi-ment of a desired morphology of small catalyst particlessuspendedin a solid slurry.

The suspended-slurry material may be fabricated by mix-ing catalyst particles in a solution containing Polytetra■uo-roethylene (PTFE) nano-particles. The mixture is mechani-cally worked and the viscosity increasesuntil the material canbe rolled into a sheet.After repeatedly folding and re-rollingthe material it becomes a rubbery membrane-like sheet,which canberolled to speci■cthickness anddried. Physicallythe PTFE particles create bridges between the catalyst par-ticles, and asthe material is mechanically worked, the PTFEis drawn into ■lamentsbetween the catalyst particles, creat-ing a structure conceptually similar to what is shown sche-matically in FIG. 1.

The suspended-slurry structure has a narrow size distribu-tion of particles uniformly spatially distributed, as illustratedin FIG. 1, and where the PTFE has minimal impact on theaccessibility of the Pt catalyst. For proof-of-concept, one ofthe focuses was on fabricating materials that could be testedwith minimal effort on optimizing the structure. While someeffort was made to investigate and standardizethe fabrication

processusing amechanical rolling machine, amanual rolling

process was found to be more reliable and repeatable. Evenwith this process, signi■cant variability was observed in thebehavior of the material. In some instances, starting from the

same recipe, the material would become ■aky instead ofrubbery. Other times, the material would form cracks duringthe drying process. The micrograph in FIG. 2 shows anexample of a suspended-slurry structure.

Proof-of-principle experiments were performed with 0.25-inch diameter circular samples punched from sheetsof sus-pended-slurry material. The sampleswere loaded in a mem-brane test cell and heated with resistance heaters wrappedaround the cell. The test cell 100, as shown in FIG. 3, con-sisted of a 0.25 inch Swagelok ■tting and an upper and lower0.25 inch stainless steel tubes. The test cell 100 includesTe■ono-rings 110,porous metal sheets120 and slurry sample130. The slurry sample 130 was supported on both sideswith

a 50% dense stainless steel porous metal sheet 120 and thecell was sealedby compressing the upper and bottom tubes

US 9,289,741 B25

against the Te■on o-rings 110 using standard 0.25 inchSwagelok nuts and tubes were sealedagainst the ■tting using0.25 inch Te■onferrules.

A number of materials were made and tested with varyingthicknesses and catalyst loadings. Performance was charac-terized by ■tting H2 yield (conversion) data to a kinetic rateexpression that is ■rst order in perhydro-N—ethylcarbazole(NEC) concentration to obtain a rate constant. This is a sim-pli■cation of the 3-step reaction sequence that produces 3hydrogen molecules per carbazole, but facilitates comparingrelative performance to the target. A rate constant of 0.91 s'1corresponds to the catalyst productivity target of 2 gHz/min/

gPtat 90% H2 yield. FIG. 4A showsthat the target productiv-ity can be achieved with this suspendedslurry concept. Theperformance of the 0.15 mm thick suspendedslurry is 8.5xbetter than a packed bed of 210-400 um particles at a similarbed diameter.

Factors that affect suspended-slurry reactor performance

arecatalyst loading, thickness, pressuredrop, and the amountof Platinum catalyst that is accessibleto the reactants. FIGS.4A and 4B show that thinner suspendedslurries have highercatalyst utilization. Stacking 2 layers of the 0.27 mm thicksamples gave minimal additional H2 production over thesingle layer, as shown in FIG. 4B, while stacking of 5 layersdid provide additional H2, albeit at lower catalyst productiv-ity. Comparisons were also made of different catalyst load-ings up to 96 wt % catalyst. FIG. 5 showsthe effect of catalystloading on performance. In general, higher catalyst loadingsshow higher productivities, which is attributed to more acces-sibility of the Ptihigher PTFE fractions causesmore cover-age of the particle surface. Table 1 below shows that com-pared to the powder catalyst only 34-59% of the Pt isaccessible in the suspended slurry, as determined by H2chemisorption measurements.

TABLE 1

Hydrogen chemisorptions results indicating percentage of Pt catalystaccessible to reactants.

Wt % catalyst H2 uptake % accessible Thicknessin membrane“ (mmoles/gmt) catalyst (mm)

100% 63 100% 7(powder)

60% 35 56% 66082% 32 50% 170

93.4% 21 34% 27093.7% 29 46% 190

98% 37 59% 320

The suspendedslurry reactor implements the concept of avery thin catalyst bed with a very large ■ow area to reduce

pressure drop associatedwith small catalyst particles. Alter-native conceptsfor accomplishing this were also investigated,including coating catalyst onto thin pieces of porous sinteredmetal FeCrAlY. Results shown in FIG. 6 indicate that highercatalyst productivities were achieved with the sintered metalthan with the suspendedslurry. However, catalyst loadings onthe sintered metal were signi■cantly lower than with thesuspendedslurry, soperformance was lower when compared

on a bed massbasis. In addition, variability in thickness andporosity of the sintered metal material gavepoorer reproduc-ibility. Therefore, the suspended slurry is an improvedembodiment for developing a compact, low massdehydroge-nation reactor.

The suspended slurry concept was implemented in a testreactor that was designed to produce at least 0.1 g/min of H2to support approximately 100We of power production from a

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6PEM fuel cell. The objectives were to demonstrate a reactordesign that is compact; is scalable to higher power produc-tion; is heated with a hot as stream; and can be con■guredwith multiple stages, if necessary to achieve high hydrogenyield from the carrier.

One embodiment of aplanar, laminate microreactor designthat was demonstrated is shown in FIG. 7. FIG. 7 shows oneembodiment of a suspended-slurry microreactor 200 forseparating the H2 240 generated from spent or dehydroge-nated liquid organic hydrogen carrier (LOHC) 230 using awicking structure. On the other side of each suspendedslurrysheetor membrane 220 are feed channels 215 that distributehydrogenated or feed LOHC 210 over the entire area of theslurry sheet.Adjacent to the feed channels 215 and separatedby a solid wall 260 are heat transfer channels 270 for supply-ing heat for the dehydrogenation reaction. Adequate heattransfer to the catalyst in the suspendedslurry 220 is criticalfor maintaining reaction temperature in order to achieve highcatalyst productivity. The concept is scalable to higher H2production ratesby repeating the structure shown in FIG. 7 tothe left and right. Adjacent to the slurry sheet 220 on theopposite side of the feed channel 215 is an e■luent channel280 for removing the hydrogen 240 and dehydrogenatedLOHC 230 from the reactor. An optional wick structure 235

can be placed in the ef■uent channel 280 that preferentiallysorbsthe liquid (LOHC) and enablesgravity separationof thedehydrogenated LOHC 230 from the hydrogen gas240. Onealternative for achieving high H2 yield is to have multiplestageswhere the dehydrogenated LOHC 230 is fed to a seriesof suspended-slurry reactors by feeding the LOHC 230 from

a ■rstreactor to feed LOHC 210 to a secondreactor to obtainhigher conversion. The generatedH2 240 ■owsthrough a gas■ow channel.

An objective of the Proof-of—Principlereactor shown in theembodiments of FIGS. 8, 9, 10, and 11, was to achieve 0.1g/min H2 production at a minimum of 90% conversion in adevice that reduced to practice the suspended-slurry reactorconcept shown in FIG. 7. The design basis assumeda catalystproductivity of 1 gHz/min/gPt. Based on a catalyst loading of1.025 mg Pt/cm2 in 190 pm thick suspended-slurry material,the required areais 98 cm2.The reactor concept in FIG. 7 wasimplemented in the design shown in FIGS. 8 and 9. In oneembodiment, each plate in FIG. 8 has a suspend-slurry sheetwith an active areaof about 1.375 inches by 3.1 inches for anactiveareaof about4.3in.2(27.5cmZ).In oneembodiment,Dexmet SSl3-077-DB expandedmetal screenis placed in theLOHC feed channel. The screen supports a sintered porousmetal layer and then the catalytic suspended-slurry layerbacked by a secondsintered metal layer. Dexmet SS-13-077-DB expanded metal screen is placed on top completing thestack.

FIG. 9 is acut-out of the cross-sectional view of the reactorplate of FIG. 8, in accordance with one embodiment of thepresent invention. The reactor plate 400 of FIG. 9 includes aLOHC feed channel 410, a sintered metal support layer 420,

a layer for suspendedslurry and a secondmetal support layer430, and an ef■uent channel with gasket groove 440 forsealing the device.

A secondmirror-image of the stack is placed on top of the■rst in a clamshell, so eachtwo-plate assemblyhas 55 cm2 of

area. The assembly is bolted together and has a feed port onone endand an ef■uentport at the other. Holes are also drilledfor 3 thermocouples to be inserted in the feed channelbetween the heat transfer plate and the suspended-slurry tomeasure local temperatures in the feed channel. Two 2-plate

US 9,289,741 B27

assemblies are stacked together in the 100-Watt Proof-of-Principle III reactor to obtain a total of 110 cm2 of activesuspended-slurry area.

The heat exchanger elements for heating with a hot gaswere extruded aluminum structures. The dimensions of the■ow channels are 1 mm><3.1mm separatedby 0.3 mm websthat provide extendedheat transfer area,and the total width is7.8 cm with 60 ■ow channels. Sections of the material werecut to 3.49 cm length and placed on both sides of the reactorclamshell assembly as shown in FIG. 10, which representsone reactor 500 repeat unit. The reactor 500 of FIG. 10includes a channel 510 for liquid entering the reactor 500 and

achannel 520 for liquid andhydrogen exiting the reactor 500.The reactor 500 also includes heat exchangers 530 and ther-mocouple tubes 550.

High temperature heat transfer pastewas applied betweenthe heat exchanger elements and the reactor plates. Two reac-tor repeat units were stackedtogether and a hot-gas manifoldbolted onto the front of the assembly as shown in FIG. 11,which representsthe complete 100-Watt-scale Proof-of—Prin-ciple reactor.

Heat transfer calculations were performed to estimate the■ow rate and temperature of hot gas needed to generate 0.1g/min of H2.Using 51.7kJ/mol H2 for the heat of reaction, thecalculated heat duty was 57.5 W including 15 W of sensibleduty. The assumed contributions to the overall heat transfercoef■cient were hot gas convective resistance, wall resis-tance, and conduction through the LOHC feed channel. Thebene■tsof the support screen and convection in the LOHCfeed channel were neglected. The overall heat transfer resis-tance was estimated to be 120 cm2~K/W, with 72% beingattributed to the LOHC channel.At 20 SLPM of hot gas■ow,this heat transfer coef■cientwill supply the required heat ■uxwith a temperature drop from 380° C. hot gas inlet tempera-ture to 253° C. outlet temperature.

A notable step in demonstrating the Proof-of—Principlereactor was scaling up the suspended-slurry area from 0.14cm2 in the test cell to 27.5 cm2 for each of 4 pieces in thereactor, representing two orders of magnitude increase in

area. Consequently, an intermediate scale-up was performedwith a 1/2-inchtest cell that had an active area of 0.7 cm2.Results from the larger test cell showeda signi■cant decreasein suspended-slurry performance. The possible explanationsincluded heat transfer limitations, higher incidence of pinholes in the larger area, and inconsistency in thickness andstructure of the suspend slurry. A series of packed bed testswere performed to better understand the relative importanceof heat and mass transfer in this reaction system. The impor-tance of heat transfer relative to mass transfer was investi-gated by comparing results from two tube diameters at the

samespacevelocity and at the same linear velocity. In addi-tion, the effect of diluting the catalyst bed with inert particles

was also measuredto discern the importance of heat transfer.Finally, the particles were also diluted to understand the rela-tive importance of interparticle mass transfer.

Thehigher apparentactivity in the smaller diameter packedbed at the same linear velocity, as evidenced by the data inFIG. 12, indicates the heat transfer limitations of the packedbed reactor, becausethe masstransfer limitations are compa-rable. This conclusion is further supported when the smallerdiameter bed is diluted with inert particles. The lower Rey-nolds number at agiven spacevelocity is expectedto increasethe external mass transfer resistance by increasing the diffu-sion boundary layer. However, the apparent activityincreases,as shown in FIG. 12, implying that heat transfer isof greater importance than external mass transfer.

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8The importance of internal mass transfer resistance in the

particles was determined by diluting the particles. Catalystparticles containing 5 wt % Platinum were crushed to apow-der, mixed with inert alumina powder, and reformed intoparticles. FIG. 13 shows the increase in apparent activitywhen the catalyst particles are diluted, con■rming the strongeffect of internal mass transfer in the particles.

The packedbed experimental results supportedthe conclu-sion that heat transfer was limiting in the scaled-up 1/2-inchsuspended slurry reactor cell. Subsequent modi■cations toenhance heat conduction into the cell caused the activity torecover to almost the same level of the smaller 1At-inchcell.Although the same approach to enhance heat transfer is notfeasible in the proof-of-principle reactor, it accentuates theimportance of ensuring su■icient heat transfer in scaling upthe suspendedslurry reactor.

The sintered metal pieces used on both sides of the sus-pended slurry materials were obtained from ADMA withspeci■cations of 304 stainless steel, 45% dense, and 0.010inch thickness. In order to obtain more uniform ■ow distri-bution by increasing pressuredrop, the ADMA material wasdensi■edby rolling to a thickness of 0.005 inch. The reactorwas assembledwith total of 5 g of 5 wt % Pt catalyst; the tworeactor subassembliescontained 2.8 and2.2 g of catalyst. Thereactor was reduced with 100 sccm ■ow of 50% H2 in N2 at235° C. for 2 hours.

A 200-Watt heater was installed on the N2 gas supplied tothe cross-■owheat exchangers.The reactor was preheatedto235° C. before starting 10ml/min of perhydro-N-ethylcarba-zole, the initial hydrogen output was 1.4 slpm, but the hydro-

gen■owdecreasedto about 200 sccm.The decreasein hydro-

gen output was accompanied by a decrease in reactortemperature from about 235° C. to 200° C. In addition, there

was a 25° C. temperature difference in the averagetempera-ture in the feed channels of the two reactors. Decreasing thefeed ■ow to 5 ml/min caused the reactor temperatures toincreaseto 190° C. and 215° C. and the H2 produced to dropto 180 sccm. Dropping the feed ■ow further to 1 ml/minallowed the temperatures to recover to 215° C. and 233° C.and the H2 to increaseto 320 sccm. The initial hydrogen ■owexceeded the 100 We equivalent H2 ■ow con■rming thepotential for the Proof-of—Principlereactor to meet the designproductivity. The thermal mass of the reactor, ducting, andhousing was a source of heat during reactor start-up thatproduced the high H2 ■ow. However, the 200 W heater wasundersized for maintaining the desired 230° C. reaction tem-perature in the two reactors.

Subsequently,the hot gasheaterwas replaced with a400 Wheater and needle valves were installed on the e■luent linesfrom each reactor in order to balance the ■ows. Only thesecondreactor was operatedin further testing. Operating with5 ml/min of NEC feed, and only half reactor produced 320

sccm of H2 at 210° C. average reactor temperature, whichincreased to 535 sccm at 240° C. H2 yields were 11% and18%, respectively. At the lower feed ■ow of 1.2 ml/min at238° C., 300 sccm of H2 ■ow (H2 yield of 41%).

Additional testing was performed at lower feed ■ow ratesand samplesof the spentLOHC were collected and analyzedby Air Products using a GC/MS. The samples are listed inTable 2 along with operating conditions and H2 ■ow.H2yieldis calculated based on the NEC feed ■ow rate and the mea-sured H2 production. Sample compositions are provided inTable 3 showing the breakdown of the dehydrogenated inter-mediates.H2yield is calculated by weighing the composition.There is a signi■cant discrepancy in H2 yield indicated by H2produced versus the measured composition. This is mostlikely dueto loss of the perhydro-NEC feed from a leak in the

US 9,289,741 B29

secondreactor. In addition, the compositions indicate signi■-cant bypass within the reactor that is likely due to internalleaks. For example, the dehydrogenation steps are progres-sively slower, soneatperhydro-NEC (MW 207) would not bedetected without the MW 203 intermediate unless there wasbypass. Sample 150141-119-1 contained almost 11% feedwithout any MW 203 intermediate. Yield from the NEC that

was converted reached almost 90%.

TABLE 2

Samples obtained from operating half of the POPIII reactor withcorresponding average reactor temperature H7 ■ow and yield.

Feed ■ow Time on Reactor H2 ■owSample (ml/min) stream (min) temp (° C.) (sccm) H2 yield“

15041 1.0 0-15 230 300 50%119-115041 1.0 20-30 230 180 30%119-215041 0.5 60-100 230 140 45%120-115041 1.0 120-130 230 180 30%120-1

“BasedonH2■ow.May contain some liquid from earlier time.

TABLE 3

Compositions determined by gas chromatography and mass spec ofsamples obtained during operation of the POPIII half-reactor.

MW MW MW MW H2 yield Converted

Sample 207 203 199 195 (GC/MS) H2yield“

15041- 10.9% 0% 30.3% 58.8% 79.1% 88.7%119-115041- 27.3% 16.0% 28.6% 28.1% 52.6% 72.2%119-215041- 20.6% 15.6% 32.0% 31.8% 58.3% 73.5%120-115041- 35.9% 19.4% 29.4% 15.4% 41.4% 64.7%120-2

“Yield from the perhydro-NEC that was converted to at least MW 203.

The Proof-of—Principlereactor shown in FIG. 10 was takenapart, the four suspended-slurry sheetswere replaced, and thereactor reassembledwith new gaskets.Additional testing wasperformed with both of the clamshell reactors operating overa range of ■ow of perhydro-NEC and at 190° C., 200° C.,220° C., and 240° C. The data in FIG. 14 show measurementsof the amount of H2 produced from the reactor at a giventemperature and feed ■owrate of carbazole along with curves■ttedto the data.The ■ttedcurves areconverted to conversionrates by mass balance which are shown in FIG. 15. FIG. 15also showsthe calculated averageresidencetime basedon theinternal void volume in the reactor and the feed ■owrate. Thereactor was able to produce over 1liter of hydrogen at 240° C.with 42% conversion of carbazole at a feed ■ow rate of 4.0ml/min of carbazole feed.

Moderate successwas achieved in meeting the objectivesof the Proof-of—Principlereactor. While H2 ■ow required for100Weequivalent power was achieved, it was at signi■cantlylower than the 90% target H2yield. This was attributed to bothexternal and internal leaks which prevented all the feed frombeing processedthrough the suspendedslurry. Assuming allof the unreactedperhydro-NEC was bypass,then the H2yieldapproachedthe desired 90%. Developing better control of thesuspended slurry thickness in the fabrication process andfuture design modi■cations will alleviate these dif■culties.

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10The core of the Proof-of—Principlereactorithe active sus-

pended-slurry area times the stack height including heatexchangersithat would need to be scaled-up for a givenapplication is 75 ml and has a heat exchange area to volumeratio of 149mZ/m3.Achieving the designgoal of 100Weequivalent power at 90% LOHC conversion would give apower density of 1.3kW/L. This translates into a total reactorvolume of 45 liters (1.6 ft3) for a 60 kWe primary power plantfor a vehicle. There is high con■dencethat this is achievablewith additional suspended-slurry development and reactordesign iterations. In addition, the power density could beincreasedby 2.4><if the bestmeasured suspend-slurry perfor-

mance was realized in a reactor. Furthermore, there is thepotential for an increase of 33x if the suspended-slurry per-formance were to approach the intrinsic kinetics of the cata-lyst.

FIG. 16 illustrates an exploded assembly view of a sus-pended-slurry reactor 600, in accordance with anotherembodiment of the present invention. The reactor 600includes heat exchanges610, reactor plates 620, and a gasket630. The reactor 600 also includes feed channels615, e■luentchannels 640, porous metal sheets660, and suspended-slurrysheetsor membrane 670. The reactor 600 further includes aninlet 602, an outlet 604, tubes for thermocouples 635, andbolts 690.

The present invention has been described in terms of spe-ci■c embodiments incorporating details to facilitate theunderstanding of the principles of construction and operationof the invention. As such, references herein to speci■cembodiments and details thereof arenot intended to limit the

scope of the claims appended hereto. It will be apparent tothose skilled in the art that modi■cations can be made in theembodiments chosen for illustration without departing fromthe spirit and scopeof the invention.

We claim:1. An apparatusfor generating a large volume of gas from

a liquid stream, comprising:

a. a ■rst channel through which the liquid stream passes;b. a layer of catalyst particles suspendedin a solid slurry,

through which the liquid streampassesfrom one side ofthe catalyst layer to the other, for generating gasfrom theliquid stream; and

c. a secondchannel through which a mixture of convertedliquid and generated gas passes,wherein the ■rst andsecond channels are located on opposite sides of thecatalyst layer.

2. The apparatus of claim 1 further comprising a heatexchange channel for heating the liquid stream.

3. The apparatus of claim 1 further comprising a wickingstructure located in the secondchannel for separating the gasgenerated from the converted liquid.

4. The apparatus of claim 1 wherein the liquid stream is aliquid organic hydrogen carrier and the generated gas ishydrogen.

5. The apparatus of claim 1 wherein the catalyst particlescomprise at least one of the following: Pt/AlZO3 andPd/A1203.

6. The apparatus of claim 1 wherein the catalyst particles

are approximately 2 um or less.7. The apparatus of claim 1 wherein the solid slurry con-

sists of catalyst particles held together in a solid-like matrixwith a polymer.

8. The apparatusof claim 7 wherein the polymer is Te■on.9. The apparatus of claim 7 wherein the catalyst particles

comprise at least 90% by mass of the solid slurry.

US 9,289,741 B211

10. The apparatus of claim 7 wherein greater than 50% ofthe catalyst is accessible relative to 100% catalyst particles.

11.The apparatusof claim 2 further comprising astructuralelement in the ■rst channel to support the suspendedslurryand to improve heat transfer.

12. The apparatusof claim 1 wherein the suspendedslurryis less than about 0.5 mm thick.

13. The apparatusof claim 1 wherein the suspendedslurryis less than about 0.15 mm thick.

14. The apparatusof claim 1 wherein the suspendedslurryis in a sheetwith an areato thickness ratio of at least 10 mm.

15. The apparatusof claim 1 wherein the suspendedslurryis in asheetwith anareato thickness ratio of at least 1000mm.

16. The apparatusof claim 1 wherein the suspendedslurryis in a sheetwith an areato thickness ratio of at least 10,000

m.17.An apparatusfor generating a large volume of gasfrom

a liquid stream, comprising:

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12a. a ■rst channel through which the liquid stream passes;b. a layer of catalyst particles suspendedin a solid slurry,

through which the liquid streampassesfrom one side ofthe catalyst layer to the other, for generating gasfrom theliquid stream;

c. a secondchannel through which a mixture of convertedliquid and generated gas passes,wherein the ■rst andsecond channels are located on opposite sides of thecatalyst layer;

d. a heat exchange channel for heating the liquid stream;and

e. a wicking structure located in the second channel forseparating the gas generated from the converted liquid;

wherein the liquid stream is a liquid organic hydrogen carrierand the generated gas is hydrogen, and the solid slurry con-tains catalyst particles held together in a solid-like matrixwith a polymer.

(12)united states patent us 9,289,741 b2availabletechnologies.pnnl.gov/media/418_52201695044.pdf ·...

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