Synthesis of ZSM-5 monoliths with hierarchical porosity through a steam-assisted crystallization method using sponges as scaffolds

Article abstract of DOI:10.1016/S1872-2067(17)62828-6

Self-supporting ZSM-5 crystals with hierarchical porosity were prepared through a steam-assisted crystallization method using sponges as rigid scaffolds. The synthesized materials were characterized by X-ray diffraction, nitrogen sorption, scanning electron microscopy, transmission electron microscopy, solid-state nuclear magnetic resonance spectroscopy and ammonia temperature-programmed desorption. The ZSM-5 monoliths exhibited high crystallinities, hierarchical porous structures and strong acidities. They showed superior catalytic performance in the liquid-phase esterification reaction between benzyl alcohol and hexanoic acid.

Full text of DOI:10.1016/S1872-2067(17)62828-6

ChineseꢀJournalꢀofꢀCatalysisꢀ38ꢀ(2017)ꢀ872–878
ꢀ
ꢀ ꢀ ꢀ
ꢀ ꢀ ꢀ ꢀ
a v a i l a b l e a t w w w . s c i e n c e d i r e c t . c o m
ꢀ
j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / c h n j c
ꢀ
ꢀ
Article
SynthesisꢀofꢀZSM‐5ꢀmonolithsꢀwithꢀhierarchicalꢀporosityꢀthroughꢀaꢀ
steam‐assistedꢀcrystallizationꢀmethodꢀusingꢀspongesꢀasꢀscaffoldsꢀ
TiejingꢀHu,ꢀJianꢀLiu,ꢀChangyanꢀCaoꢀ*,ꢀWeiguoꢀSongꢀ#
ꢀ
BeijingꢀNationalꢀLaboratoryꢀforꢀMolecularꢀSciences,ꢀLaboratoryꢀforꢀMolecularꢀNanostructuresꢀandꢀNanotechnology,ꢀInstituteꢀofꢀChemistry,ꢀChineseꢀ
AcademyꢀofꢀSciences,ꢀBeijingꢀ100190,ꢀChinaꢀ
UniversityꢀofꢀChineseꢀAcademyꢀofꢀSciences,ꢀBeijingꢀ100049,ꢀChinaꢀ
A R T I C L E ꢀ I N F O ꢀ
A B S T R A C T ꢀ
Articleꢀhistory:ꢀ
Self‐supportingꢀZSM‐5ꢀcrystalsꢀwithꢀhierarchicalꢀporosityꢀwereꢀpreparedꢀthroughꢀaꢀsteam‐assistedꢀ
crystallizationꢀmethodꢀusingꢀspongesꢀasꢀrigidꢀscaffolds.ꢀTheꢀsynthesizedꢀmaterialsꢀwereꢀcharacter‐
izedꢀ byꢀX‐rayꢀdiffraction,ꢀ nitrogenꢀ sorption,ꢀ scanningꢀelectronꢀmicroscopy,ꢀ transmissionꢀ electronꢀ
microscopy,ꢀ solid‐stateꢀ nuclearꢀ magneticꢀ resonanceꢀ spectroscopyꢀ andꢀ ammoniaꢀ tempera‐
ture‐programmedꢀdesorption.ꢀTheꢀZSM‐5ꢀmonolithsꢀexhibitedꢀhighꢀcrystallinities,ꢀhierarchicalꢀpo‐
rousꢀ structuresꢀ andꢀ strongꢀ acidities.ꢀ Theyꢀ showedꢀ superiorꢀ catalyticꢀ performanceꢀ inꢀ theꢀ liq‐
uid‐phaseꢀesterificationꢀreactionꢀbetweenꢀbenzylꢀalcoholꢀandꢀhexanoicꢀacid.ꢀ
Receivedꢀ24ꢀFebruaryꢀ2017ꢀ
Acceptedꢀ27ꢀMarchꢀ2017ꢀ
Publishedꢀ5ꢀMayꢀ2017ꢀ
Keywords:ꢀ
Hierarchicallyꢀporousꢀstructureꢀ
Zeoliteꢀ
Steam‐assistedꢀcrystallizationꢀ
Acidity
©ꢀ2017,ꢀDalianꢀInstituteꢀofꢀChemicalꢀPhysics,ꢀChineseꢀAcademyꢀofꢀSciences.
PublishedꢀbyꢀElsevierꢀB.V.ꢀAllꢀrightsꢀreserved.
1
.ꢀ ꢀ Introductionꢀ
[9,10]ꢀ andꢀ aerogelsꢀ [11,12]ꢀ haveꢀ beenꢀ investigated.ꢀ However,ꢀ
theseꢀprocessesꢀwereꢀsomewhatꢀexpensiveꢀandꢀtimeꢀconsum‐
ing.ꢀCationicꢀpolymersꢀhaveꢀalsoꢀbeenꢀsuccessfullyꢀemployedꢀtoꢀ
produceꢀhierarchicalꢀzeolitesꢀ[13,14],ꢀbutꢀtheꢀsyntheticꢀzeolitesꢀ
wereꢀnotꢀsuitableꢀforꢀindustrialꢀcatalysis.ꢀ
Inꢀtheꢀcaseꢀofꢀindustrialꢀcatalysis,ꢀaꢀcertainꢀamountꢀofꢀbind‐
ers,ꢀ suchꢀ asꢀ alumina,ꢀ silicaꢀ orꢀ clay,ꢀ isꢀ generallyꢀ usedꢀ forꢀ ce‐
mentingꢀ zeoliteꢀcrystalsꢀintoꢀlargeꢀ sticksꢀorꢀgranulesꢀthatꢀ areꢀ
mechanicallyꢀstable.ꢀHowever,ꢀtheꢀinorganicꢀbindersꢀmayꢀdiluteꢀ
theꢀ activeꢀ zeoliteꢀ andꢀ partiallyꢀ blockꢀ theꢀ poreꢀ system,ꢀ whichꢀ
resultsꢀinꢀdiffusionꢀlimitationsꢀandꢀinaccessibilityꢀofꢀtheꢀactiveꢀ
speciesꢀ[15].ꢀToꢀovercomeꢀtheseꢀproblems,ꢀcontinuousꢀprogressꢀ
hasꢀbeenꢀmadeꢀonꢀtheꢀdevelopmentꢀofꢀmechanicallyꢀstableꢀzeo‐
liteꢀmonolithsꢀwithꢀuniformꢀshapesꢀandꢀhierarchicalꢀstructures.ꢀ
Suchꢀmonolithicꢀzeoliteꢀmaterialsꢀfacilitateꢀtheꢀdiffusionꢀofꢀtheꢀ
reactantsꢀ andꢀ productsꢀ asꢀ wellꢀ asꢀ theꢀ reactionꢀ efficiencyꢀ andꢀ
Hierarchicallyꢀ structuredꢀ porousꢀ materialsꢀ haveꢀ triggeredꢀ
extensiveꢀresearchꢀbecauseꢀofꢀtheirꢀfascinatingꢀfeaturesꢀsuchꢀasꢀ
highꢀsurfaceꢀareas,ꢀinterface‐facilitatedꢀtransportꢀandꢀadvancedꢀ
massꢀ transportꢀkineticsꢀ [1–3].ꢀRecently,ꢀ thereꢀ haveꢀ beenꢀ suc‐
cessfulꢀ attemptsꢀ toꢀ synthesizeꢀ hierarchicallyꢀ porousꢀ zeolites.ꢀ
Forꢀexample,ꢀpost‐synthesisꢀtreatmentsꢀcanꢀbeꢀusedꢀtoꢀgenerateꢀ
hierarchicallyꢀ porousꢀ zeolitesꢀ throughꢀ selectiveꢀ leachingꢀ ofꢀ
aluminumꢀ (dealumination)ꢀ orꢀ siliconꢀ (desilication)ꢀ fromꢀ theꢀ
zeoliteꢀframeworkꢀ[4,5].ꢀTheꢀmajorꢀdisadvantageꢀofꢀsuchꢀaꢀpro‐
cessꢀisꢀtheꢀpartialꢀdegradationꢀofꢀtheꢀcrystallineꢀnatureꢀofꢀtheꢀ
zeolite,ꢀandꢀconsequently,ꢀaꢀreductionꢀinꢀtheꢀcatalyticꢀactivity.ꢀ
Moreꢀrecently,ꢀotherꢀprocessesꢀtoꢀcreateꢀzeolitesꢀwithꢀaꢀhierar‐
chicalꢀporosityꢀusingꢀaꢀhardꢀsacrificialꢀtemplatesꢀhaveꢀalsoꢀbeenꢀ
examined;ꢀ carbonꢀ materialsꢀ [6–8],ꢀ mesoporousꢀ silicaꢀ spheresꢀ
*
ꢀ
ꢀCorrespondingꢀauthor.ꢀTel/Fax:ꢀ+86‐10‐62557908;ꢀE‐mail:ꢀcycao@iccas.ac.cnꢀ ꢀ
Correspondingꢀauthor.ꢀTel/Fax:ꢀ+86‐10‐62557908;ꢀE‐mail:ꢀwsong@iccas.ac.cn
#
ThisꢀworkꢀwasꢀsupportedꢀbyꢀtheꢀNationalꢀNaturalꢀScienceꢀFoundationꢀofꢀChinaꢀ(21333009)ꢀandꢀtheꢀYouthꢀInnovationꢀPromotionꢀAssociationꢀofꢀCASꢀ
2017049).ꢀ
DOI:ꢀ10.1016/S1872‐2067(17)62828‐6ꢀ|ꢀhttp://www.sciencedirect.com/science/journal/18722067ꢀ|ꢀChin.ꢀJ.ꢀCatal.,ꢀVol.ꢀ38,ꢀNo.ꢀ5,ꢀMayꢀ2017ꢀ ꢀ ꢀ
(

ꢀ
TiejingꢀHuꢀetꢀal.ꢀ/ꢀChineseꢀJournalꢀofꢀCatalysisꢀ38ꢀ(2017)ꢀ872–878ꢀ
873ꢀ
canꢀ beꢀ usedꢀ inꢀ practicalꢀ application.ꢀ Forꢀ example,ꢀ Shiꢀ etꢀ al.ꢀ
16,17]ꢀhaveꢀreportedꢀtheꢀpreparationꢀofꢀHSZsꢀbyꢀusingꢀordi‐
naryꢀmesoporogensꢀsuchꢀasꢀtriethanolamineꢀ(TEA),ꢀP123,ꢀF127ꢀ
andꢀevenꢀsucroseꢀasꢀinꢀsituꢀcarbonaceousꢀtemplates.ꢀRyooꢀetꢀal.ꢀ
edꢀspongeꢀwasꢀadsorbedꢀwithꢀappropriateꢀquantityꢀofꢀTPAOH.ꢀ
TheꢀTPAOH/Siꢀmolarꢀratioꢀwasꢀmaintainedꢀasꢀ0.27.ꢀTheꢀdriedꢀ
spongeꢀ containingꢀ silica,ꢀ aluminumꢀ andꢀ TPAOHꢀ wasꢀ placedꢀ
insideꢀaꢀTeflon‐linedꢀautoclaveꢀcontainingꢀ2ꢀmLꢀofꢀdistilledꢀwa‐
terꢀforꢀsteam‐assistedꢀcrystallization.ꢀTheꢀautoclaveꢀwasꢀclosedꢀ
andꢀplacedꢀinꢀaꢀhotꢀairꢀovenꢀatꢀ130ꢀ°Cꢀforꢀ36ꢀh.ꢀAfterꢀtheꢀcrystal‐
lizationꢀperiod,ꢀtheꢀautoclaveꢀwasꢀtakenꢀoutꢀandꢀquenchedꢀtoꢀ
roomꢀtemperature.ꢀTheꢀproductꢀwasꢀcollected,ꢀdriedꢀatꢀ80ꢀ°Cꢀ
forꢀ8ꢀhꢀandꢀthenꢀcalcinedꢀatꢀ550ꢀ°Cꢀforꢀ8ꢀhꢀinꢀairꢀtoꢀremoveꢀtheꢀ
TPAOHꢀ andꢀ theꢀ sponge.ꢀ Theꢀ synthesisꢀ ofꢀ M‐ZSM‐40ꢀ andꢀ
M‐ZSM‐90ꢀwithꢀdifferentꢀSi/Alꢀratiosꢀwereꢀsimilarlyꢀconductedꢀ
byꢀaccordinglyꢀchangingꢀtheꢀAIPꢀcontentꢀinꢀtheꢀprecursorꢀsolu‐
tionꢀwhileꢀkeepingꢀtheꢀadditionꢀofꢀTEOSꢀconstant.ꢀForꢀcompar‐
ison,ꢀtraditionalꢀZSM‐5ꢀ(denotedꢀasꢀZSM‐5(60))ꢀwasꢀsynthesisꢀ
[
[18]ꢀdesignedꢀseveralꢀbifunctionalꢀtemplates,ꢀcombingꢀtheꢀfea‐
turesꢀofꢀbothꢀstructuralꢀguideꢀagentꢀ(SDA)ꢀandꢀmesoporogensꢀ
withinꢀ oneꢀ molecule,ꢀ andꢀ successfullyꢀ synthesizedꢀ zeoliteꢀ
nanosheetsꢀwithꢀhierarchicalꢀstructures.ꢀHowever,ꢀtheꢀreportedꢀ
synthesisꢀ ofꢀ theꢀ hierarchicallyꢀ structuredꢀ zeolitesꢀ byꢀ massiveꢀ
mesoporogensꢀwasꢀneitherꢀcostꢀefficientꢀnorꢀfriendlyꢀbecauseꢀ
mostꢀofꢀtheꢀtemplateꢀagentsꢀwereꢀdifficultꢀtoꢀmakeꢀandꢀnocu‐
ous.ꢀNovelꢀsynthesisꢀroutesꢀusingꢀfewꢀmesoporogensꢀareꢀhighlyꢀ
desirableꢀandꢀhaveꢀbecomeꢀaꢀpromisingꢀresearchꢀfield.ꢀ
Inꢀ thisꢀ study,ꢀ weꢀ preparedꢀ high‐qualityꢀ zeoliteꢀ monolithsꢀ
withꢀhierarchicalꢀporosityꢀthroughꢀaꢀsteam‐assistedꢀcrystalliza‐
tionꢀ(SAC)ꢀmethodꢀusingꢀspongesꢀasꢀrigidꢀscaffolds.ꢀX‐rayꢀdif‐
fractionꢀ (XRD)ꢀ andꢀ nuclearꢀ magneticꢀ resonanceꢀ (NMR)ꢀ spec‐
troscopyꢀ analysisꢀ showedꢀ theꢀ ZSM‐5ꢀ monolithsꢀ wereꢀ highlyꢀ
crystalline.ꢀBecauseꢀofꢀtheirꢀhierarchicalꢀporousꢀstructure,ꢀtheꢀ
zeoliteꢀ monolithsꢀ hadꢀ aꢀ higherꢀ surfaceꢀ area,ꢀ strongerꢀ acidity,ꢀ
andꢀ showedꢀ betterꢀ catalyticꢀ activityꢀ thanꢀ thatꢀ ofꢀ traditionalꢀ
ZSM‐5ꢀinꢀtheꢀliquidꢀphaseꢀesterificationꢀreaction.ꢀ
withꢀaꢀmolarꢀratioꢀofꢀ28Na
2
O:1Al
2
O
3
:120SiO
2
:4000H O.ꢀ ꢀ
2
2.3.ꢀ ꢀ Catalysisꢀconditionsꢀ
Priorꢀtoꢀtheꢀcatalyticꢀtests,ꢀallꢀtheꢀmaterialsꢀwereꢀexchangedꢀ
toꢀtheꢀH‐formꢀwithꢀanꢀaqueousꢀsolutionꢀofꢀNH
4
NO ꢀ(1.0ꢀmol/L)ꢀ
3
+
atꢀ90ꢀ°Cꢀforꢀ4ꢀhꢀandꢀthenꢀconvertedꢀtoꢀtheꢀH ꢀformꢀthroughꢀcal‐
cinationꢀatꢀ550ꢀ°Cꢀforꢀ5ꢀh.ꢀEsterificationꢀofꢀtheꢀalcoholꢀwithꢀanꢀ
acidꢀ wasꢀ carriedꢀ outꢀ inꢀ aꢀ double‐neckedꢀ roundꢀ bottomꢀ flaskꢀ
fittedꢀwithꢀaꢀrefluxꢀcondenser.ꢀTheꢀalcoholꢀ(15ꢀmmol),ꢀacidꢀ(18ꢀ
mmol)ꢀandꢀtolueneꢀ(15ꢀmL)ꢀwereꢀaddedꢀtoꢀtheꢀroundꢀbottomꢀ
flask,ꢀasꢀwellꢀasꢀn‐nonane,ꢀwhichꢀisꢀanꢀinternalꢀstandard.ꢀTheꢀ
solutionꢀwasꢀheatedꢀtoꢀ110ꢀ°Cꢀusingꢀaꢀsiliconeꢀoilꢀbathꢀandꢀthenꢀ
250ꢀmgꢀofꢀtheꢀ catalystꢀ wasꢀadded.ꢀ Theꢀreactionꢀmixtureꢀ wasꢀ
stirredꢀ usingꢀ aꢀ magneticꢀ stirrerꢀ andꢀ theꢀ stirringꢀ speedꢀ wasꢀ
maintainedꢀatꢀ1200ꢀr/minꢀtoꢀavoidꢀexternalꢀmassꢀtransferꢀlimi‐
tations.ꢀ Theꢀ reactionꢀ productsꢀ wereꢀ analyzedꢀ byꢀ GCꢀ (Agilentꢀ
6890ꢀ N)ꢀ withꢀ aꢀ capillaryꢀ columnꢀ (DB‐5,ꢀ 30.0ꢀ mꢀ ×ꢀ 320ꢀ mmꢀ ×ꢀ
0.25ꢀmm)ꢀandꢀFID,ꢀandꢀtheꢀproductsꢀwereꢀfurtherꢀidentifiedꢀbyꢀ
GC‐MSꢀ (Shimadzu,ꢀ GCMS‐QPꢀ 2010S)ꢀ withꢀ aꢀ capillaryꢀ columnꢀ
(DB‐5ꢀms,ꢀ30.0ꢀmꢀ×ꢀ320ꢀmmꢀ×ꢀ0.25ꢀmm).ꢀ
2.ꢀ ꢀ Experimentalꢀ
2.1.ꢀ ꢀ Reagentsꢀ ꢀ
Tetraethylorthosilicateꢀ(TEOS,ꢀ98ꢀwt%),ꢀtetrapropylammo‐
niumhydroxideꢀ (TPAOH,ꢀ 25ꢀ wt%),ꢀ hexanoicꢀ acidꢀ (98.8%),ꢀ
benzylꢀ alcoholꢀ (98.8%),ꢀ ammoniumꢀ nitrateꢀ (98.5%),ꢀ tolueneꢀ
(
(
3
99.5%),ꢀ4‐methylbenzylꢀalcoholꢀ(98%),ꢀ4‐nitrobenzylꢀalcoholꢀ
98%),ꢀ 4‐methoxybenzylꢀ alcoholꢀ (98%)ꢀ andꢀ
‐phenylpropan‐1‐olꢀ wereꢀ purchasedꢀ fromꢀ J&Kꢀ Corporation.ꢀ
Aluminumꢀisopropoxideꢀ(AIP,ꢀ97%)ꢀwasꢀobtainedꢀfromꢀBeijingꢀ
Chemicalꢀ Reagentꢀ Corporationꢀ (Beijing,ꢀ China).ꢀ Aqueousꢀ am‐
moniaꢀ solutionꢀ (28%ꢀ inꢀ H
2
O),ꢀ sodiumꢀ hydroxideꢀ andꢀ ethanolꢀ
(99.9%)ꢀwereꢀpurchasedꢀfromꢀBeijingꢀChemicalꢀCompany.ꢀAllꢀ
2.4.ꢀ ꢀ Characterizationꢀ
theꢀ reagentsꢀ wereꢀ usedꢀ withoutꢀ furtherꢀ purification.ꢀ Nano‐
spongesꢀwereꢀpurchasedꢀfromꢀHenan.ꢀ
Theꢀ morphologyꢀ andꢀ sizeꢀ ofꢀ theꢀ resultantꢀ powdersꢀ wereꢀ
characterizedꢀ withꢀ aꢀ fieldꢀ emissionꢀ scanningꢀ electronꢀ micro‐
scopeꢀ(FESEMꢀJEOL‐6701F).ꢀTransmissionꢀelectronꢀmicroscopyꢀ
2.2.ꢀ ꢀ Preparationꢀofꢀzeoliteꢀmonolithsꢀ ꢀ
(TEM)ꢀimagesꢀwereꢀtakenꢀusingꢀaꢀJEM‐2100Fꢀ(JEOL)ꢀoperatedꢀ
Theꢀspongesꢀwereꢀcutꢀintoꢀsmallꢀcubesꢀthatꢀwereꢀsuitableꢀforꢀ
atꢀ 100ꢀ kV.ꢀ Powerꢀ XRDꢀ patternsꢀ wereꢀ collectedꢀ onꢀ aꢀ
Rigaku‐2500ꢀinꢀtheꢀ2θꢀrangeꢀofꢀ5°–55°.ꢀTheꢀrelativeꢀcrystallini‐
tyꢀ (RC)ꢀ ofꢀ theꢀ synthesizedꢀ M‐ZSMsꢀ wasꢀ calculatedꢀ fromꢀ theꢀ
ratioꢀofꢀtheꢀsumꢀofꢀtheꢀintensitiesꢀofꢀtheꢀfourꢀmostꢀintenseꢀre‐
flectionsꢀ inꢀ theꢀ 2θꢀ rangeꢀ ofꢀ 22.5°−24°ꢀ andꢀ theꢀ correspondingꢀ
sumꢀofꢀtheꢀparentꢀZSM‐5,ꢀwhichꢀwasꢀpurchasedꢀfromꢀtheꢀCata‐
theꢀsizeꢀofꢀtheꢀautoclave.ꢀToꢀsynthesizeꢀM‐ZSM‐60ꢀ(Mꢀindicatesꢀ
monolith,ꢀ ZSMꢀ representsꢀ ZSM‐5ꢀ zeolite,ꢀ 60ꢀ representsꢀ theꢀ
synthesizedꢀmaterialsꢀwithꢀSi/Alꢀmolarꢀratioꢀofꢀ60),ꢀ ꢀ 0.275ꢀgꢀofꢀ
AIPꢀwasꢀdissolvedꢀinꢀ16ꢀmLꢀofꢀethanolꢀatꢀroomꢀtemperatureꢀforꢀ
ꢀhꢀandꢀthenꢀaddedꢀtoꢀ14ꢀgꢀofꢀTEOS.ꢀTheꢀsolutionꢀwasꢀstirredꢀforꢀ
ꢀ hꢀ andꢀ thenꢀ theꢀ spongeꢀ wasꢀ immersedꢀ inꢀ theꢀ solution.ꢀ Theꢀ
2
5
lystꢀPlantꢀofꢀNankaiꢀUniversity.ꢀN
ꢀadsorptionꢀisothermsꢀwereꢀ
2
impregnatedꢀspongeꢀwasꢀthenꢀplacedꢀintoꢀaꢀTeflon‐linedꢀauto‐
claveꢀcontainingꢀ2ꢀmLꢀofꢀ30%ꢀaqueousꢀammoniaꢀsolution.ꢀTheꢀ
autoclaveꢀwasꢀthenꢀclosedꢀandꢀtreatedꢀatꢀ80ꢀ°Cꢀforꢀ12ꢀhꢀinꢀaꢀhotꢀ
airꢀoven.ꢀTheꢀautoclaveꢀwasꢀthenꢀquenchedꢀtoꢀroomꢀtempera‐
tureꢀandꢀtheꢀspongeꢀwasꢀonceꢀagainꢀimpregnatedꢀwithꢀtheꢀeth‐
anolꢀ solutionꢀ containingꢀ AIPꢀ andꢀ TEOS.ꢀ Thisꢀ procedureꢀ wasꢀ
repeatedꢀ threeꢀ timesꢀ toꢀ ensureꢀ efficientꢀ loadingꢀ ofꢀ theꢀ silicaꢀ
sourceꢀandꢀaluminumꢀsourceꢀintoꢀtheꢀsponge.ꢀTheꢀfinallyꢀload‐
measuredꢀ atꢀ −196ꢀ °Cꢀ onꢀ aꢀ Quantachromeꢀ Autosorbꢀ AS‐1ꢀ in‐
strument;ꢀtheꢀsamplesꢀwereꢀoutgassedꢀatꢀ120ꢀ°Cꢀforꢀ12ꢀhꢀpriorꢀ
toꢀtesting.ꢀPoreꢀsizeꢀdistributionsꢀwereꢀevaluatedꢀfromꢀtheꢀad‐
sorptionꢀ isothermsꢀ usingꢀ theꢀ Barret‐Joyner‐Halendaꢀ (BJH)ꢀ
formulaꢀ andꢀ theꢀ microporousꢀ volumeꢀ wasꢀ evaluatedꢀ byꢀ non‐
localꢀ densityꢀ functionalꢀ theory.ꢀ 27Alꢀ andꢀ 29Siꢀ solid‐stateꢀ NMRꢀ
spectroscopyꢀexperimentsꢀ wereꢀperformedꢀonꢀanꢀ AVANCEꢀIIIꢀ
400WBꢀspectrometer.ꢀTheꢀspectraꢀwereꢀcollectedꢀatꢀaꢀfrequen‐

874ꢀ
TiejingꢀHuꢀetꢀal.ꢀ/ꢀChineseꢀJournalꢀofꢀCatalysisꢀ38ꢀ(2017)ꢀ872–878ꢀ
2
7
cyꢀofꢀ104.1ꢀMHzꢀ(0.4ꢀsꢀrecycleꢀdelayꢀtime)ꢀforꢀ Al‐NMRꢀandꢀatꢀaꢀ
templateꢀ producedꢀ approximatelyꢀ 2ꢀ gꢀ ofꢀ zeolite,ꢀ indicatingꢀ aꢀ
highꢀyieldꢀbasedꢀonꢀtheꢀproposedꢀsyntheticꢀstrategy.ꢀBecauseꢀ
theꢀspongeꢀscaffoldsꢀareꢀeasyꢀtoꢀhandle,ꢀM‐ZSMsꢀmonolithsꢀwithꢀ
differentꢀshapesꢀandꢀsizesꢀcanꢀbeꢀproduced,ꢀwhichꢀwouldꢀfacili‐
tateꢀtheirꢀpotentialꢀapplications.ꢀ ꢀ
29
frequencyꢀofꢀ79.3ꢀMHzꢀ(2ꢀsꢀrecycleꢀdelayꢀtime)ꢀforꢀ Si‐NMR.ꢀ
CompressiveꢀstrengthꢀtestsꢀwereꢀconductedꢀinꢀanꢀInstron5567.ꢀ
SiO
metricꢀmeasurementsꢀwereꢀperformedꢀonꢀaꢀNetzschꢀSTAꢀ494Cꢀ
Jupiterꢀ TG/DSCꢀ instrument.ꢀ Ammoniaꢀ tempera‐
ture‐programmedꢀdesorptionꢀ(NH ‐TPD)ꢀwasꢀconductedꢀusingꢀ
/Al O
2 2 3
ꢀmolarꢀratiosꢀwereꢀ analyzedꢀbyꢀXRF.ꢀThermogravi‐
TheꢀstrongꢀBrönstedꢀacidityꢀofꢀZSM‐5ꢀzeoliteꢀoriginatesꢀfromꢀ
3+
4+
3
theꢀheterogeneousꢀsubstitutionꢀofꢀAl ꢀwithꢀSi ꢀinꢀtheꢀframe‐
work.ꢀ However,ꢀbecauseꢀofꢀtheꢀdifferenceꢀinꢀtheꢀchemicalꢀva‐
lenceꢀandꢀionicꢀradiusꢀbetweenꢀAlꢀandꢀSi,ꢀsuchꢀaꢀsubstitutionꢀisꢀ
limitedꢀ[19].ꢀHere,ꢀtoꢀextendꢀtheꢀrangeꢀofꢀtheꢀhierarchicalꢀzeo‐
litesꢀwithꢀvariableꢀSi/Alꢀratiosꢀandꢀsurfaceꢀacidity,ꢀandꢀconse‐
quently,ꢀtoꢀsatisfyꢀtheꢀrequirementsꢀforꢀdiverseꢀcatalyticꢀappli‐
cations,ꢀ M‐ZSMsꢀ withꢀ variedꢀ Si/Alꢀ ratiosꢀ fromꢀ 40ꢀ toꢀ 90ꢀ wereꢀ
preparedꢀunderꢀidenticalꢀconditionsꢀatꢀaꢀfixedꢀTPAOH/Siꢀratioꢀ
ofꢀ0.25ꢀ(Tableꢀ1,ꢀentriesꢀ1,ꢀ2ꢀandꢀ3).ꢀTheꢀsynthesesꢀofꢀM‐ZSMsꢀ
withꢀdifferentꢀSi/AlꢀratiosꢀwereꢀconductedꢀbyꢀchangingꢀtheꢀAIPꢀ
contentꢀ inꢀ theꢀ precursorꢀ solutionꢀ andꢀ keepingꢀ theꢀ amountꢀ ofꢀ
TEOSꢀconstant.ꢀ
aꢀMicromeriticsꢀAutochemꢀ2920ꢀinstrument.ꢀTheꢀcatalystꢀ(0.15ꢀ
g)ꢀwasꢀchargedꢀinꢀaꢀU‐shapedꢀquartzꢀcellꢀandꢀpretreatedꢀinꢀArꢀ
(
20ꢀ mL/min)ꢀ atꢀ 500ꢀ °Cꢀ forꢀ 1ꢀ hꢀ (rampꢀ rateꢀ 10ꢀ °C/min)ꢀ thenꢀ
cooledꢀtoꢀ100ꢀ°C.ꢀTheꢀgasꢀflowꢀwasꢀthenꢀchangedꢀtoꢀaꢀmixtureꢀofꢀ
0%ꢀNH ‐90%ꢀArꢀ(40ꢀmL/min)ꢀforꢀ2ꢀh.ꢀTheꢀsampleꢀwasꢀthenꢀ
purgedꢀwithꢀArꢀ(20ꢀmL/min)ꢀatꢀ100ꢀ°Cꢀforꢀ2ꢀhꢀtoꢀremoveꢀfreeꢀ
andꢀ weaklyꢀ adsorbedꢀ ammonia.ꢀ Theꢀ NH ‐TPDꢀ profileꢀ wasꢀ
measuredꢀbyꢀrisingꢀtheꢀtemperatureꢀupꢀtoꢀ600ꢀ°Cꢀ(rampꢀrateꢀ10ꢀ
C/min)ꢀusingꢀaꢀTCDꢀdetector.ꢀ
1
3
3
°
3.ꢀ ꢀ Resultsꢀandꢀdiscussionꢀ
TheꢀmicrostructureꢀofꢀtheꢀobtainedꢀM‐ZSM‐60ꢀmonolithꢀwasꢀ
characterizedꢀ byꢀ SEMꢀ andꢀ TEM.ꢀ Asꢀ shownꢀ inꢀ Fig.ꢀ 1(a),ꢀ theꢀ
spongeꢀscaffoldꢀhadꢀanꢀinterconnectingꢀmacroporousꢀstructure.ꢀ
Theꢀ obtainedꢀ M‐ZSM‐60ꢀ monolithꢀ wasꢀ composedꢀ ofꢀ manyꢀ
denseꢀ blocks,ꢀ amongꢀ whichꢀ macroporesꢀ wereꢀ formedꢀ (Fig.ꢀ
1(b)).ꢀTheꢀhigh‐magnificationꢀSEMꢀimageꢀshowedꢀthatꢀtheꢀzeo‐
liteꢀ consistedꢀ ofꢀ manyꢀ close‐packedꢀ particlesꢀ (Fig.ꢀ 1(c)).ꢀ Theꢀ
TEMꢀimageꢀfurtherꢀconfirmedꢀthatꢀtheꢀmonolithicꢀzeoliteꢀcon‐
sistedꢀofꢀintergrownꢀparticlesꢀwithꢀaꢀglobularꢀmorphologyꢀ(Fig.ꢀ
1(d)).ꢀTheꢀcorrespondingꢀSAEDꢀpatternꢀdemonstratedꢀtheꢀgoodꢀ
crystallinityꢀ ofꢀ theꢀ zeoliteꢀ (insetꢀ inꢀ Fig.ꢀ 1(d)).ꢀ Theꢀ elementalꢀ
mappingꢀimagesꢀofꢀM‐ZSM‐60ꢀshowedꢀthatꢀtheꢀSiꢀandꢀAlꢀwereꢀ
uniformlyꢀdispersedꢀinꢀtheꢀM‐ZSM‐60.ꢀ ꢀ
Schemeꢀ 1ꢀ illustratesꢀ theꢀ synthesisꢀ ofꢀ M‐ZSMꢀ monolithꢀ
throughꢀtheꢀSACꢀmethodꢀwithꢀaꢀspongeꢀasꢀaꢀrigidꢀscaffold.ꢀFirst,ꢀ
TEOSꢀ (siliconꢀ source)ꢀ andꢀ AIPꢀ (aluminumꢀ source)ꢀ wereꢀ dis‐
persedꢀ inꢀ ethanolꢀ toꢀ formꢀ aluminosilicateꢀ seeds,ꢀ whichꢀ wereꢀ
thenꢀadsorbedꢀbyꢀtheꢀPUFꢀsponge.ꢀTheꢀspongeꢀwasꢀthenꢀtreatedꢀ
underꢀhydrothermalꢀconditionsꢀinꢀanꢀautoclaveꢀusingꢀtheꢀSACꢀ
methodꢀ withꢀ ammoniumꢀ hydroxideꢀ asꢀ steam.ꢀ Theꢀ sameꢀ pro‐
cessꢀwasꢀrepeatedꢀthreeꢀtimesꢀtoꢀloadꢀmoreꢀseeds,ꢀensuringꢀtheꢀ
mechanicalꢀstabilityꢀofꢀtheꢀfinalꢀmonolithicꢀproduct.ꢀSecond,ꢀtheꢀ
spongeꢀobtainedꢀinꢀtheꢀfirstꢀstepꢀ wasꢀ impregnatedꢀ inꢀ TPAOHꢀ
solutionꢀtoꢀadsorbꢀanꢀappropriateꢀquantityꢀofꢀtheꢀtemplateꢀandꢀ
thenꢀ crystallizedꢀ underꢀ hydrothermalꢀ conditionsꢀ inꢀ anꢀ auto‐
claveꢀthroughꢀtheꢀSACꢀmethodꢀwithꢀH
2
Oꢀasꢀsteam.ꢀFinally,ꢀtheꢀ
Fig.ꢀ 2(a)ꢀ showsꢀ theꢀ correspondingꢀ XRDꢀ patternsꢀ ofꢀ theꢀ
M‐ZSMsꢀ withꢀ differentꢀ Si/Alꢀ ratiosꢀ andꢀ traditionalꢀ ZSM‐5ꢀ forꢀ
comparison.ꢀ Allꢀ diffractionꢀ peaksꢀ couldꢀ beꢀ indexedꢀ toꢀ theꢀ
standardꢀZSM‐5.ꢀNoꢀotherꢀpeaksꢀwereꢀobserved,ꢀindicatingꢀtheꢀ
purityꢀofꢀtheꢀobtainedꢀM‐ZSMs.ꢀMoreover,ꢀdependingꢀonꢀtheꢀAlꢀ
dopingꢀcontent,ꢀtheꢀcalculatedꢀRCꢀincreasedꢀfromꢀ88%ꢀforꢀsam‐
pleꢀ M‐ZSM‐40ꢀ toꢀ 98%ꢀ forꢀ sampleꢀ M‐ZSM‐90ꢀ (Tableꢀ 1).ꢀ Thisꢀ
resultꢀsuggestedꢀthatꢀtheꢀincreaseꢀofꢀAlꢀcontentꢀinꢀM‐ZSMsꢀisꢀ
unfavorableꢀ forꢀ theꢀ crystallizationꢀ transformationꢀ duringꢀ SACꢀ
treatment.ꢀ
M‐ZSMꢀ monolithꢀ wasꢀ obtainedꢀ afterꢀ calcinationꢀ atꢀ 550ꢀ °Cꢀ toꢀ
removeꢀtheꢀspongeꢀandꢀtheꢀTPAOHꢀtemplate.ꢀAsꢀshownꢀinꢀtheꢀ
photosꢀ(Schemeꢀ1),ꢀtheꢀzeoliteꢀmonolithꢀmaintainedꢀtheꢀshapeꢀ
ofꢀtheꢀoriginalꢀspongeꢀtemplateꢀafterꢀtheꢀsequentialꢀtreatments.ꢀ
Dependingꢀ onꢀ theꢀ exactꢀ conditions,ꢀ 0.1ꢀ gꢀ ofꢀ theꢀ nanospongeꢀ
Theꢀ obtainedꢀ M‐ZSMsꢀ wereꢀ furtherꢀ characterizedꢀ byꢀ NMRꢀ
spectroscopyꢀtoꢀconfirmꢀtheꢀstructureꢀofꢀtheꢀzeoliteꢀframework.ꢀ
Asꢀ shownꢀ inꢀ Fig.ꢀ 2(b),ꢀ theꢀ 29Siꢀ MAS‐NMRꢀ spectraꢀ clearlyꢀ
showedꢀ oneꢀ majorꢀ bandꢀ withꢀ aꢀ chemicalꢀ shiftꢀ atꢀ −112ꢀ ppmꢀ
correspondingꢀtoꢀSi(OSi)
4
(Q ),ꢀwhichꢀsuggestedꢀthatꢀmostꢀofꢀtheꢀ
4
siliconꢀatomsꢀwereꢀlocatedꢀinꢀQ ꢀsites,ꢀasꢀexpectedꢀforꢀaꢀsilicateꢀ
4
Tableꢀ1ꢀ
Texturalꢀparameters,ꢀcomposition,ꢀandꢀRCꢀofꢀallꢀtheꢀsynthesizedꢀmate‐
rials.ꢀ
Reactionꢀ Reactionꢀ
Entry Sampleꢀ Si/Al timeꢀ temperatureꢀ
S
BETꢀ
V
poreꢀ
RCꢀ
2
3
(
m /g)ꢀ (cm /g) (%)
(h)ꢀ
(°C)ꢀ
1
ꢀ
M‐ZSM‐40 42
M‐ZSM‐60 64
M‐ZSM‐90 91
ZSM‐5(60) 63
36ꢀ
36ꢀ
36ꢀ
36ꢀ
130ꢀ
130ꢀ
130ꢀ
130ꢀ
452ꢀ
440ꢀ
463ꢀ
432ꢀ
0.62ꢀ
0.43ꢀ
0.29ꢀ
0.22ꢀ
88
94
98
92
2
ꢀ
3
ꢀ
Schemeꢀ1.ꢀSchematicꢀillustrationꢀforꢀtheꢀsynthesisꢀofꢀtheꢀM‐ZSMsꢀmon‐
oliths.ꢀ
4ꢀ

ꢀ
TiejingꢀHuꢀetꢀal.ꢀ/ꢀChineseꢀJournalꢀofꢀCatalysisꢀ38ꢀ(2017)ꢀ872–878ꢀ
875ꢀ
Fig.ꢀ1.ꢀSEMꢀimagesꢀofꢀ(a)ꢀtheꢀoriginalꢀspongeꢀandꢀ(b,ꢀc)ꢀM‐ZSM‐60,ꢀTEMꢀimageꢀofꢀ(d)ꢀM‐ZSM‐60ꢀ(Topꢀrightꢀandꢀbottomꢀright:ꢀtheꢀcorrespondingꢀSAEDꢀ
pattern).ꢀ
(a)
–112
100
(b)
(c)
–
5
5
–105
0
(
1)
2)
3)
(4)
-200
(
1)
2)
3)
4)
(
(
3)
(
(2)
(
(
(
1)
(
4)
(
10
20
30
(°)
40
50
-100
 /ppm
0
120 100 80 60 40 20
0
-20 -40
2
 /ppm
Fig.ꢀ2.ꢀ(a)ꢀ XRDꢀ patterns,ꢀ(b)ꢀ29Siꢀ andꢀ(c)ꢀ 27AlꢀNMRꢀMASꢀspectraꢀofꢀtheꢀM‐ZSMsꢀandꢀZSM‐5(60).ꢀ(1)ꢀM‐ZSM‐40;ꢀ(2)ꢀ M‐ZSM‐60;ꢀ(3)ꢀ MZSM‐90;ꢀ(4)
ZSM‐5(60).ꢀ
framework.ꢀTheꢀ shoulderꢀ peakꢀatꢀ−100ꢀ ppmꢀwasꢀ ascribedꢀtoꢀ
HO)Si(OSi) (Q ),ꢀalsoꢀimplyingꢀthatꢀtheꢀMFIꢀzeoliteꢀwasꢀhighlyꢀ
crystalline.ꢀFurthermore,ꢀanotherꢀweakꢀshoulderꢀpeakꢀatꢀ−105ꢀ
ppmꢀwasꢀascribedꢀtoꢀ(AlO)‐Si(OSi) ,ꢀsuggestingꢀtheꢀexistenceꢀofꢀ
someꢀamorphousꢀsilicateꢀspeciesꢀinꢀtheꢀmonolithicꢀzeolites.ꢀTheꢀ
27AlꢀMAS‐NMRꢀspectraꢀ(Fig.ꢀ2(c))ꢀexhibitedꢀtwoꢀpeaksꢀatꢀ~55ꢀ
ppmꢀandꢀ0ꢀppm.ꢀTheꢀpeakꢀatꢀ~55ꢀppmꢀwasꢀascribedꢀtoꢀalumi‐
numꢀ speciesꢀ withꢀ tetrahedralꢀ coordination.ꢀ Theꢀ peakꢀ withꢀ aꢀ
lowerꢀintensityꢀatꢀ~0ꢀppmꢀwasꢀassignedꢀtoꢀtheꢀoctahedralꢀAlꢀinꢀ
theꢀ formꢀ ofꢀ polymericꢀ oxo‐hydroxo‐Al‐cationsꢀ andꢀ ex‐
tra‐frameworkꢀAlꢀspeciesꢀorꢀtheꢀframeworkꢀAlꢀspeciesꢀlocatedꢀ
atꢀtheꢀdefectꢀsites.ꢀ
microporosityꢀ andꢀ mesoporosity.ꢀ Theꢀ correspondingꢀ surfaceꢀ
areasꢀandꢀporeꢀvolumesꢀareꢀlistedꢀinꢀTableꢀ1.ꢀ
(
3
3
Fig.ꢀ4(a)ꢀpresentsꢀtheꢀNH ‐TPDꢀprofilesꢀforꢀZSM‐5(60)ꢀandꢀ
3
3
theꢀM‐ZSMs.ꢀTheꢀdensityꢀofꢀtheꢀsurfaceꢀacidꢀsitesꢀincreasedꢀinꢀ
theꢀ orderꢀ ZSM‐5(60)ꢀ <ꢀ M‐ZSM‐90ꢀ <ꢀ M‐ZSM‐40ꢀ <ꢀ M‐ZSM‐60.ꢀ
3
ThereꢀwereꢀtwoꢀNH ꢀdesorptionꢀpeaksꢀforꢀZSM‐5(60)ꢀandꢀtheꢀ
450
4
00
50
3
300
(2)
Nitrogenꢀ adsorption‐desorptionꢀ experimentsꢀ wereꢀ carriedꢀ
outꢀtoꢀdetermineꢀtheꢀtexturalꢀporosityꢀofꢀtheꢀobtainedꢀM‐ZSMsꢀ
monolithsꢀ(Fig.ꢀ3).ꢀTheꢀisothermꢀofꢀZSM‐5(60)ꢀexhibitedꢀaꢀtypi‐
calꢀtype‐Iꢀprofileꢀwithꢀaꢀhighꢀuptakeꢀatꢀlowꢀrelativeꢀpressuresꢀ
2
2
1
50
00
50
(1)
3)
4)
(
(
(
p/p0
ꢀ
<ꢀ0.1)ꢀandꢀaꢀplateauꢀatꢀhighꢀrelativeꢀpressuresꢀ(0.4ꢀ<ꢀp/p0
ꢀ
100
<
ꢀ1.0),ꢀindicatingꢀthatꢀtheꢀresultantꢀmaterialsꢀhadꢀaꢀpurelyꢀmi‐
5
0
croporousꢀphaseꢀwithꢀnegligibleꢀmesoporosity.ꢀForꢀM‐ZSM‐90,ꢀ
aꢀ similarꢀ type‐Iꢀ isothermꢀ wasꢀ observed.ꢀ However,ꢀ forꢀ
M‐ZSM‐40ꢀ andꢀ M‐ZSM‐60,ꢀ typicalꢀ type‐IVꢀ isothermsꢀ withꢀ ob‐
viousꢀ hysteresisꢀ loopsꢀ andꢀ apparentꢀ uptakesꢀ atꢀ highꢀ relativeꢀ
pressuresꢀwereꢀobserved,ꢀdemonstratingꢀtheꢀexistenceꢀofꢀbothꢀ
0.0
0.2
0.4
0.6
0.8
1.0
Relative pressure (p/p0)
Fig.ꢀ 3.ꢀ N ꢀ adsorption‐desorptionꢀ isothermsꢀ ofꢀ theꢀ M‐ZSMsꢀ andꢀ
2
ZSM‐5(60).ꢀ (1)ꢀ M‐ZSM‐40;ꢀ (2)ꢀ M‐ZSM‐60;ꢀ (3)ꢀ M‐ZSM‐90;ꢀ (4)ꢀ
ZSM‐5(60).ꢀ

876ꢀ
TiejingꢀHuꢀetꢀal.ꢀ/ꢀChineseꢀJournalꢀofꢀCatalysisꢀ38ꢀ(2017)ꢀ872–878ꢀ
Conversion
Selectivity
(c)
Conversion
Selectivity
(
a)
(b)
(
2)
1)
3)
4)
100
100
80
60
40
20
0
(
(
(
80
60
40
20
0
1
00
200
300
400
o
500
600
1
2
3
4
5
Temperature ( C)
Fig.ꢀ4.ꢀ(a)ꢀNH ‐TPDꢀcurvesꢀofꢀ(1)ꢀM‐ZSM‐40,ꢀ(2)ꢀM‐ZSM‐60,ꢀ(3)ꢀM‐ZSM‐90,ꢀ(4)ꢀZSM‐5(60)ꢀandꢀZSM‐5(60);ꢀ(b)ꢀCatalyticꢀconversionꢀandꢀselectivityꢀofꢀ
3
theꢀM‐ZSMsꢀandꢀZSM‐5(60)ꢀcatalystsꢀinꢀtheꢀesterificationꢀreactionꢀbetweenꢀbenzylꢀalcoholꢀandꢀhexanoicꢀacid;ꢀ(c)ꢀRecyclingꢀofꢀtheꢀM‐ZSM‐60ꢀcatalystꢀ
inꢀtheꢀesterificationꢀreactionꢀbetweenꢀbenzylꢀalcoholꢀandꢀhexanoicꢀacid.ꢀ
M‐ZSMs,ꢀwhichꢀwereꢀattributedꢀtoꢀweakꢀandꢀstrongꢀacidicꢀsites.ꢀ
Generally,ꢀ theꢀ peakꢀ atꢀ aꢀ higherꢀ temperatureꢀ isꢀ relatedꢀ toꢀ aꢀ
strongꢀacidꢀsite,ꢀwhichꢀwasꢀattributedꢀtoꢀtheꢀAl‐OH‐Siꢀbridgeꢀinꢀ
theꢀ 10‐memberꢀ ringꢀ (10ꢀ MR)ꢀ ofꢀ ZSM‐5.ꢀ Theꢀ peakꢀ atꢀ aꢀ lowerꢀ
temperatureꢀwasꢀattributedꢀtoꢀaꢀweakꢀorꢀmediumꢀstrengthꢀacidꢀ
site,ꢀ whichꢀ wasꢀ associatedꢀ withꢀ theꢀ nonframeworkꢀ Alꢀ atomsꢀ
andꢀ zeoliteꢀ defects.ꢀ Theꢀ peaksꢀforꢀtheꢀM‐ZSMsꢀ wereꢀ strongerꢀ
thanꢀ thoseꢀ forꢀ ZSM‐5(60),ꢀ indicatingꢀ thatꢀ theꢀ acidityꢀ ofꢀ theꢀ
M‐ZSMsꢀwasꢀhigherꢀthanꢀthatꢀofꢀZSM‐5(60).ꢀItꢀwasꢀunusualꢀthatꢀ
M‐ZSM‐60ꢀhadꢀaꢀhigherꢀacidꢀdensityꢀthanꢀM‐ZSM‐40.ꢀItꢀisꢀlikelyꢀ
thatꢀtheꢀmethodꢀusedꢀinꢀthisꢀworkꢀdoesꢀnotꢀallowꢀhighꢀalumi‐
numꢀ contentꢀ intoꢀ theꢀ MFIꢀ framework.ꢀ Asꢀ shownꢀ inꢀ Fig.ꢀ 2(c),ꢀ
thereꢀwasꢀaꢀsignificantꢀamountꢀofꢀextra‐frameworkꢀAlꢀspeciesꢀ
onꢀM‐ZSM‐40,ꢀindicatingꢀthatꢀlessꢀAlꢀatomsꢀwereꢀincorporatedꢀ
intoꢀtheꢀframework.ꢀ
Brönstedꢀacidsꢀlocatedꢀatꢀtheꢀsurfaceꢀofꢀtheꢀmesoporousꢀwallsꢀ
[20].ꢀThus,ꢀtheꢀlowꢀconversionꢀofꢀZSM‐5(60)ꢀcouldꢀbeꢀattribut‐
edꢀtoꢀdiffusionꢀlimitationsꢀowingꢀtoꢀitsꢀsmallꢀporeꢀdiameter.ꢀTheꢀ
highꢀcatalyticꢀactivitiesꢀofꢀM‐ZSM‐60ꢀandꢀM‐ZSM‐40ꢀindicatedꢀ
thatꢀhierarchicalꢀframeworksꢀ canꢀleadꢀtoꢀeasierꢀ accessꢀtoꢀtheꢀ
activeꢀsitesꢀforꢀreactantsꢀandꢀfasterꢀdiffusionꢀofꢀproducts.ꢀTheseꢀ
resultsꢀwereꢀconsistentꢀwithꢀtheꢀNH
‐TPDꢀresults.ꢀ
3
Hierarchicallyꢀstructuredꢀzeolitesꢀcanꢀbeꢀusedꢀinꢀmanyꢀotherꢀ
catalyticꢀreactionsꢀinvolvingꢀlargeꢀmolecules,ꢀinꢀwhichꢀdiffusionꢀ
constraintsꢀ and/orꢀ theꢀ adsorptionꢀ ofꢀ theꢀ reactantꢀ moleculesꢀ
ontoꢀtheꢀacidꢀsitesꢀareꢀtheꢀmainꢀconcern.ꢀVariousꢀesterificationꢀ
reactionsꢀ ofꢀ alcoholsꢀ andꢀ acidsꢀ couldꢀ alsoꢀ beꢀ catalyzedꢀ withꢀ
highꢀyieldsꢀ(Tableꢀ2),ꢀindicatingꢀtheꢀsuperiorꢀefficiencyꢀofꢀtheꢀ
M‐ZSMsꢀcatalyst.ꢀTheꢀreactantsꢀcontainingꢀanꢀelectron‐donatingꢀ
−
groupꢀ(MeO )ꢀshowedꢀaꢀhigherꢀreactivityꢀrelativeꢀtoꢀthoseꢀcon‐
−
Theꢀliquid‐phaseꢀesterificationꢀreactionꢀbetweenꢀbenzylꢀal‐
coholꢀandꢀhexanoicꢀacidꢀwasꢀthenꢀemployedꢀasꢀaꢀprobeꢀreactionꢀ
toꢀ examineꢀ theꢀ catalyticꢀ performanceꢀ ofꢀ theꢀ M‐ZSMsꢀ andꢀ
ZSM‐5(60).ꢀTheꢀM‐ZSMsꢀexhibitedꢀhigherꢀconversionsꢀofꢀbenzylꢀ
alcoholꢀthanꢀZSM‐5(60)ꢀ(Fig.ꢀ4(b)).ꢀTheꢀesterificationꢀreactionꢀ
involvesꢀlargeꢀmolecularꢀspecies,ꢀwhichꢀisꢀmainlyꢀcatalyzedꢀbyꢀ
tainingꢀelectronꢀwithdrawingꢀgroupsꢀ(NO
2
;ꢀTableꢀ2,ꢀentriesꢀ3ꢀ
andꢀ4).ꢀFurthermore,ꢀtheꢀM‐ZSM‐60ꢀcatalystꢀshowedꢀgoodꢀre‐
cyclabilityꢀ(Fig.ꢀ4(c)).ꢀ
4.ꢀ ꢀ Conclusionsꢀ
ZSM‐5ꢀmonolithsꢀwithꢀhierarchicalꢀporousꢀstructuresꢀwereꢀ
preparedꢀthroughꢀaꢀsteam‐assistedꢀcrystallizationꢀmethodꢀus‐
ingꢀ spongesꢀ asꢀ rigidꢀ scaffolds.ꢀ TheꢀobtainedꢀZSM‐5ꢀmonolithsꢀ
wereꢀ characterizedꢀ byꢀ XRDꢀ andꢀ NMR.ꢀ Theꢀ ZSM‐5ꢀ monolithsꢀ
wereꢀ highlyꢀ crystalline.ꢀ Owingꢀ toꢀ theirꢀ hierarchicalꢀ porousꢀ
structure,ꢀtheyꢀhadꢀstrongꢀacidityꢀandꢀexhibitedꢀsuperiorꢀcata‐
lyticꢀperformanceꢀinꢀtheꢀliquid‐phaseꢀesterificationꢀreaction.ꢀ
Tableꢀ2ꢀ
Theꢀ esterificationꢀ reactionꢀ withꢀ differentꢀ alcoholsꢀ andꢀ hexanoicꢀ acidꢀ
usingꢀM‐ZSM‐60ꢀasꢀaꢀcatalyst.ꢀ
ꢀ
Substrateꢀ
R)ꢀ
Timeꢀ Conversionꢀ Selectivityꢀ
Entryꢀ
(
(h)ꢀ
(%)ꢀ
(%)ꢀ
1ꢀ
8ꢀ
47ꢀ
ꢀ 94ꢀ
Referencesꢀ
OHꢀ
[
1] M.ꢀE.ꢀDavis,ꢀNature,ꢀ2002,ꢀ417,ꢀ813−821.ꢀ
2
ꢀ
8ꢀ
3ꢀ
8ꢀ
8ꢀ
59ꢀ
95ꢀ
32ꢀ
50ꢀ
100ꢀ
ꢀ 87ꢀ
100ꢀ
100ꢀ
ꢀ
[2] Y.ꢀGuo,ꢀY.ꢀJin,ꢀH.ꢀWu,ꢀL.ꢀZhou,ꢀQ.ꢀChen,ꢀX.ꢀZhang,ꢀX.ꢀLi,ꢀInt.ꢀJ.ꢀHydro‐
genꢀEnergy,ꢀ2014,ꢀ39,ꢀ21044−21052.ꢀ
[3] S.ꢀ Lopez‐Orozco,ꢀ A.ꢀ Inayat,ꢀ A.ꢀ Schwab,ꢀ T.ꢀ Selvam,ꢀ W.ꢀ Schwieger,ꢀ
Adv.ꢀMater.,ꢀ2011,ꢀ23,ꢀ2602−2615.ꢀ
3ꢀ
ꢀ
[4] S.ꢀ Abello,ꢀ A.ꢀ Bonilla,ꢀ J.ꢀ Perez‐Ramirez,ꢀ Appl.ꢀ Catal.ꢀ A,ꢀ 2009,ꢀ 364,ꢀ
91−198.ꢀ
4ꢀ
1
ꢀ
[5] D.ꢀ Verboekend,ꢀ J.ꢀ Perez‐Ramirez,ꢀ Chem.ꢀ Eur.ꢀ J.,ꢀ 2011,ꢀ 17,ꢀ
5ꢀ
1137−1147.ꢀ
ꢀ
[6] H.ꢀKatsuki,ꢀS.ꢀFuruta,ꢀT.ꢀWatari,ꢀS.ꢀKomarneni,ꢀMicroporousꢀMeso‐
porousꢀMater.,ꢀ2005,ꢀ86,ꢀ145−151.ꢀ
Reactionꢀconditions:ꢀcatalystꢀ250ꢀmg,ꢀ15ꢀmmolꢀalcohol,ꢀ18ꢀmmolꢀacid,ꢀ
5ꢀmLꢀtoluene,ꢀ5ꢀmmolꢀn‐nonane.ꢀ
1
[7] C.ꢀMadsen,ꢀC.ꢀJ.ꢀH.ꢀJacobsen,ꢀChem.ꢀCommun.,ꢀ1999,ꢀ8,ꢀ673−674.ꢀ

ꢀ
TiejingꢀHuꢀetꢀal.ꢀ/ꢀChineseꢀJournalꢀofꢀCatalysisꢀ38ꢀ(2017)ꢀ872–878ꢀ
GraphicalꢀAbstractꢀ
877ꢀ
Chin.ꢀJ.ꢀCatal.,ꢀ2017,ꢀ38:ꢀ872–878ꢀ ꢀ ꢀ doi:ꢀ10.1016/S1872‐2067(17)62828‐6
SynthesisꢀofꢀZSM‐5ꢀmonolithsꢀwithꢀhierarchicalꢀporosityꢀthroughꢀaꢀsteam‐assistedꢀcrystallizationꢀmethodꢀusingꢀspongesꢀasꢀ
scaffoldsꢀ
ꢀ
TiejingꢀHu,ꢀJianꢀLiu,ꢀChangyanꢀCaoꢀ*,ꢀWeiguoꢀSong*ꢀ
InstitueꢀofꢀChemistry,ꢀChineseꢀAcademyꢀofꢀSciences;ꢀUniversityꢀofꢀChineseꢀAcademyꢀofꢀSciencesꢀ
Self‐supportingꢀZSM‐5ꢀcrystalsꢀwithꢀhierarchicalꢀporosityꢀwereꢀpreparedꢀthroughꢀaꢀsteam‐assistedꢀcrystallizationꢀmethodꢀusingꢀspongesꢀ
asꢀrigidꢀscaffolds.ꢀTheꢀsynthesizedꢀZSM‐5ꢀmonolithsꢀexhibitedꢀhighꢀcrystallinity,ꢀhierarchicalꢀporousꢀstructuresꢀandꢀstrongꢀacidities.ꢀ
[
8] Y.ꢀ S.ꢀ Tao,ꢀ H.ꢀ Kanoh,ꢀ K.ꢀ Kaneko,ꢀ J.ꢀ Phys.ꢀ Chem.ꢀ B,ꢀ 2003,ꢀ 107,ꢀ
0974−10976.ꢀ
[15] S.ꢀMitchell,ꢀN.ꢀL.ꢀMichels,ꢀK.ꢀKunze,ꢀJ.ꢀPerez‐Ramirez,ꢀNat.ꢀChem.,ꢀ
2012,ꢀ4,ꢀ825−831.ꢀ
1
[
9] A.ꢀG.ꢀDong,ꢀN.ꢀRen,ꢀW.ꢀL.ꢀYang,ꢀY.ꢀJ.ꢀWang,ꢀY.ꢀH.ꢀZhang,ꢀD.ꢀJ.ꢀWang,ꢀJ.ꢀ
[16] J.ꢀZhou,ꢀZ.ꢀL.ꢀHua,ꢀJ.ꢀL.ꢀShi,ꢀQ.ꢀJ.ꢀHe,ꢀL.ꢀM.ꢀGuo,ꢀM.ꢀL.ꢀRuan,ꢀChem.ꢀEur.ꢀ
J.,ꢀ2009,ꢀ15,ꢀ12949−12954.ꢀ
H.ꢀHu,ꢀZ.ꢀGao,ꢀY.ꢀTang,ꢀAdv.ꢀFunct.ꢀMater.,ꢀ2003,ꢀ13,ꢀ943−948.ꢀ
[
[
[
[
[
10] Z.ꢀD.ꢀWang,ꢀY.ꢀM.ꢀLiu,ꢀJ.ꢀG.ꢀJiang,ꢀM.ꢀY.ꢀHe,ꢀP.ꢀWu,ꢀJ.ꢀMater.ꢀChem.,ꢀ
010,ꢀ20,ꢀ10193−10199.ꢀ
11] Y.ꢀM.ꢀFang,ꢀH.ꢀQ.ꢀHu,ꢀG.ꢀH.ꢀChen,ꢀMicroporousꢀMesoporousꢀMater.,ꢀ
008,ꢀ113,ꢀ481−489.ꢀ
12] Y.ꢀ S.ꢀ Tao,ꢀ H.ꢀ Kanoh,ꢀ K.ꢀ Kaneko,ꢀ J.ꢀ Am.ꢀ Chem.ꢀ Soc.,ꢀ 2003,ꢀ 125,ꢀ
044−6045.ꢀ
13] H.ꢀ Wang,ꢀ T.ꢀ J.ꢀ Pinnavaia,ꢀ Angew.ꢀ Chem.ꢀ Int.ꢀ Ed.,ꢀ 2006,ꢀ 45,ꢀ
603−7606.ꢀ
[17] J.ꢀA.ꢀZhou,ꢀZ.ꢀL.ꢀHua,ꢀZ.ꢀC.ꢀLiu,ꢀW.ꢀWu,ꢀY.ꢀZhu,ꢀJ.ꢀL.ꢀShi,ꢀACSꢀCatal.,ꢀ
2011,ꢀ1,ꢀ287−291.ꢀ
2
[18] M.ꢀChoi,ꢀK.ꢀNa,ꢀJ.ꢀKim,ꢀY.ꢀSakamoto,ꢀO.ꢀTerasaki,ꢀR.ꢀRyoo,ꢀNature,ꢀ
2009,ꢀ461,ꢀ246−249.ꢀ
2
[19] http://www.iza‐structure.org/databases/.ꢀ
[20] V.ꢀN.ꢀShetti,ꢀJ.ꢀKim,ꢀR.ꢀRyoo,ꢀJ.ꢀMater.ꢀChem.,ꢀ2012,ꢀ22,ꢀ4637−4640.ꢀ
6
7
Pageꢀnumbersꢀreferꢀtoꢀtheꢀcontentsꢀinꢀtheꢀprintꢀversion,ꢀwhichꢀincludeꢀ
bothꢀtheꢀEnglishꢀversionꢀandꢀextendedꢀChineseꢀabstractꢀofꢀtheꢀpaper.ꢀTheꢀ
onlineꢀversionꢀonlyꢀhasꢀtheꢀEnglishꢀversion.ꢀTheꢀpagesꢀwithꢀtheꢀextendedꢀ
Chineseꢀabstractꢀareꢀonlyꢀavailableꢀinꢀtheꢀprintꢀversion.ꢀ
14] F.ꢀS.ꢀXiao,ꢀL.ꢀF.ꢀWang,ꢀC.ꢀY.ꢀYin,ꢀK.ꢀF.ꢀLin,ꢀY.ꢀDi,ꢀJ.ꢀX.ꢀLi,ꢀR.ꢀR.ꢀXu,ꢀD.ꢀS.ꢀ
Su,ꢀR.ꢀSchlogl,ꢀT.ꢀYokoi,ꢀT.ꢀTatsumi,ꢀAngew.ꢀChem.ꢀInt.ꢀEd.,ꢀ2006,ꢀ45,ꢀ
3090−3093.ꢀ