Alcohol-treated SiO2 as the support of Ir-Re/SiO2 catalysts for glycerol hydrogenolysis

Article abstract of DOI:10.1016/S1872-2067(16)62517-2

The surface of SiO₂ support was pretreated by C1–C4 normal alcohols before the impregnation of iridium and rhenium precursors. These catalysts were applied in high concentration glycerol aqueous solution hydrogenolysis. The catalysts prepared from the pretreated supports exhibited high catalytic activity because of the formation of more active sites from a high dispersion of iridium oxide and rhenium oxide. The catalysts with the support pretreated by 1-propanol showed the highest glycerol conversion of 59.5%. The supports and catalysts were characterized by FT-IR, nitrogen adsorption, TPR, XRD, TEM, H₂-chemisorption and NH₃-TPD.

Full text of DOI:10.1016/S1872-2067(16)62517-2

ChineseꢀJournalꢀofꢀCatalysisꢀ37ꢀ(2016)ꢀ2009–2017
ꢀ
ꢀ ꢀ ꢀ
ꢀ ꢀ ꢀ ꢀ
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
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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
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ꢀ
Article
2 2
Alcohol‐treatedꢀSiO ꢀasꢀtheꢀsupportꢀofꢀIr‐Re/SiO ꢀcatalystsꢀforꢀ ꢀ
glycerolꢀhydrogenolysisꢀ
ꢀa,c
ꢀa,# ꢀ
ꢀa
ꢀa,c
ꢀa,c
ꢀa,b,
WentingꢀLuo ,ꢀYuanꢀLyu ,LeifengꢀGong ,ꢀHongꢀDu ,ꢀMiaoꢀJiang ,ꢀYunjieꢀDing *
ꢀ
aꢀDalianꢀNationalꢀLaboratoryꢀforꢀCleanꢀEnergy,ꢀDalianꢀInstituteꢀofꢀChemicalꢀPhysics,ꢀChineseꢀAcademyꢀofꢀSciences,ꢀDalianꢀ116023,ꢀLiaoning,ꢀChinaꢀ
bꢀStateꢀKeyꢀLaboratoryꢀforꢀCatalysis,ꢀDalianꢀInstituteꢀofꢀChemicalꢀPhysics,ꢀChineseꢀAcademyꢀofꢀSciences,ꢀDalianꢀ116023,ꢀLiaoning,ꢀChinaꢀ
cꢀUniversityꢀofꢀChineseꢀAcademyꢀofꢀSciences,ꢀBeijingꢀ100049,ꢀChinaꢀ
A R T I C L E ꢀ I N F O ꢀ
A B S T R A C T ꢀ
TheꢀsurfaceꢀofꢀSiO ꢀsupportꢀwasꢀpretreatedꢀbyꢀC1–C4ꢀnormalꢀalcoholsꢀbeforeꢀtheꢀimpregnationꢀofꢀ
Articleꢀhistory:ꢀ
2
Receivedꢀ25ꢀJulyꢀ2016ꢀ
Acceptedꢀ30ꢀAugustꢀ2016ꢀ
Publishedꢀ5ꢀNovemberꢀ2016ꢀ
iridiumꢀandꢀrheniumꢀprecursors.ꢀTheseꢀcatalystsꢀwereꢀappliedꢀinꢀhighꢀconcentrationꢀglycerolꢀaque‐
ousꢀsolutionꢀhydrogenolysis.ꢀTheꢀcatalystsꢀpreparedꢀfromꢀtheꢀpretreatedꢀsupportsꢀexhibitedꢀhighꢀ
catalyticꢀactivityꢀbecauseꢀofꢀtheꢀformationꢀofꢀmoreꢀactiveꢀsitesꢀfromꢀaꢀhighꢀdispersionꢀofꢀiridiumꢀ
oxideꢀ andꢀ rheniumꢀ oxide.ꢀ Theꢀ catalystsꢀ withꢀ theꢀ supportꢀ pretreatedꢀ byꢀ 1‐propanolꢀ showedꢀ theꢀ
highestꢀglycerolꢀconversionꢀofꢀ59.5%.ꢀTheꢀsupportsꢀandꢀcatalystsꢀwereꢀcharacterizedꢀbyꢀFT‐IR,ꢀni‐
Keywords:ꢀ
Glycerolꢀhydrolysisꢀ
trogenꢀadsorption,ꢀTPR,ꢀXRD,ꢀTEM,ꢀH
2
‐chemisorptionꢀandꢀNH ‐TPD.ꢀ
3
©ꢀ2016,ꢀDalianꢀInstituteꢀofꢀChemicalꢀPhysics,ꢀChineseꢀAcademyꢀofꢀSciences.
1,3‐Propanediolꢀ
PublishedꢀbyꢀElsevierꢀB.V.ꢀAllꢀrightsꢀreserved.
Iridiumꢀ
Rheniumꢀ
Alcoholꢀpretreatment
1
.ꢀ ꢀ Introductionꢀ
1,3‐propanediolꢀ hasꢀ greatꢀ economicꢀ value.ꢀ Therefore,ꢀ theꢀ hy‐
drogenolysisꢀ ofꢀ glycerolꢀ toꢀ 1,3‐propanediolꢀ haveꢀ recentlyꢀ re‐
ceivedꢀmoreꢀattentionꢀ[5].ꢀ
Asꢀaꢀmajorꢀbyproductꢀofꢀbiodieselꢀsynthesis,ꢀcrudeꢀglycerolꢀ
willꢀaccumulateꢀtoꢀleadꢀtoꢀaꢀbigꢀenvironmentalꢀproblem,ꢀsoꢀtheꢀ
conversionꢀ ofꢀ crudeꢀ glycerolꢀ toꢀ valuableꢀ productsꢀ becomesꢀ
necessaryꢀ[1,2].ꢀAnꢀappreciableꢀnumberꢀofꢀcommodityꢀchemi‐
calsꢀandꢀchemicalꢀintermediatesꢀcanꢀbeꢀobtainedꢀfromꢀglycerolꢀ
byꢀcatalyticꢀprocessesꢀincludingꢀoxidation,ꢀdehydration,ꢀhydro‐
genolysis,ꢀ pyrolysis,ꢀ polymerization,ꢀ esterification,ꢀ steamꢀ re‐
forming,ꢀ acetalization,ꢀ transesterification,ꢀ andꢀ etherifica‐
tion[3,4].ꢀ Amongꢀ theseꢀ processes,ꢀ glycerolꢀ hydrogenolysisꢀ isꢀ
veryꢀpromising.ꢀHydrogenolysisꢀofꢀglycerolꢀgivesꢀproductsꢀsuchꢀ
Manyꢀ catalystsꢀ forꢀ glycerolꢀ hydrogenolysisꢀ wereꢀ recentlyꢀ
studied.ꢀReꢀpromotedꢀthisꢀreactionꢀwhenꢀaddedꢀtoꢀnobleꢀmetalsꢀ
suchꢀasꢀPt,ꢀRh,ꢀPd,ꢀIrꢀandꢀRuꢀ[6–14].ꢀRheniumꢀoxideꢀwillꢀformꢀ
Re‐OHꢀspeciesꢀwhenꢀitꢀisꢀexposedꢀtoꢀsteamꢀ[15].ꢀRe‐OHꢀinter‐
actsꢀwithꢀtheꢀOHꢀgroupsꢀofꢀglycerolꢀtoꢀformꢀ2,3‐
dihydroxypro‐
ꢀ
paneoxide,ꢀandꢀthenꢀhydrogenꢀspeciesꢀwillꢀactivateꢀtheꢀsecond‐
aryꢀcarbonꢀofꢀtheꢀ2,3‐dihydroxypropaneoxideꢀtoꢀcleaveꢀtheꢀC–Oꢀ
bond.ꢀThenꢀhydrolysisꢀoccursꢀtoꢀreleaseꢀtheꢀproductꢀ[8,16–19].ꢀ ꢀ
Theꢀdispersionꢀofꢀtheꢀactiveꢀmetalꢀcomponentꢀhasꢀaꢀgreatꢀin‐
fluenceꢀonꢀtheꢀcatalyticꢀperformanceꢀ[20,21].ꢀTheꢀmetalꢀdisper‐
asꢀ 1,3‐propanediol,ꢀ 1,2‐propanediol,ꢀ ethyleneꢀ glycol,ꢀ 1‐
propa‐
ꢀ
nolꢀ andꢀ 2‐propanol.ꢀ 1,3‐propanediolꢀ isꢀ theꢀ monomerꢀ ofꢀ poly‐
trimethyleneꢀ terephthalateꢀ (PTT)ꢀ andꢀ isꢀ alsoꢀ appliedꢀ inꢀ theꢀ
productionꢀ ofꢀ cosmetics,ꢀ foods,ꢀ lubricantsꢀ andꢀ medicines,ꢀ soꢀ
sionꢀ canꢀ beꢀ improvedꢀ byꢀ usingꢀ SiO ꢀ supportꢀ pretreatedꢀ withꢀ
monohydricꢀalcoholsꢀ[22],ꢀorganicꢀacidꢀ[23,24],ꢀdihydricꢀalco‐
holꢀ[25–27],ꢀalkaliꢀ[28]ꢀandꢀsilaneꢀ[24].ꢀTheseꢀsolventsꢀchangeꢀ
2
*
ꢀ
ꢀCorrespondingꢀauthor. Tel/Fax:ꢀ+86‐411‐84379143;ꢀE‐mail:ꢀdyj@dicp.ac.cnꢀ ꢀ ꢀ
Correspondingꢀauthor.ꢀTel/Fax:ꢀ+86‐411‐84379143;ꢀE‐mail:ꢀluyuan@dicp.ac.cnꢀ
#
ThisꢀworkꢀwasꢀsupportedꢀbyꢀtheꢀNationalꢀNaturalꢀScienceꢀFoundationꢀofꢀChinaꢀ(21403217).ꢀ ꢀ
DOI:ꢀ10.1016/S1872‐2067(16)62517‐2ꢀ|ꢀhttp://www.sciencedirect.com/science/journal/18722067ꢀ|ꢀChin.ꢀJ.ꢀCatal.,ꢀVol.ꢀ37,ꢀNo.ꢀ11,ꢀNovemberꢀ2016 ꢀ

2010ꢀ
WentingꢀLuoꢀetꢀal.ꢀ/ꢀChineseꢀJournalꢀofꢀCatalysisꢀ37ꢀ(2016)ꢀ2009–2017ꢀ
2
theꢀ surfaceꢀ propertyꢀ ofꢀ SiO ꢀ byꢀ decreasingꢀ surfaceꢀ hydroxylꢀ
onꢀanꢀAMI‐300ꢀcatalystꢀcharacterizationꢀsystem.ꢀApproximatelyꢀ
groups,ꢀaddingꢀorganicꢀgroupsꢀandꢀchangingꢀtheꢀhydrophobicꢀ
properties,ꢀwhichꢀleadꢀtoꢀbetterꢀdispersionꢀofꢀtheꢀactiveꢀmetalꢀ
particles.ꢀ
100ꢀmgꢀofꢀtheꢀsampleꢀwasꢀplacedꢀinꢀaꢀquartzꢀreactorꢀandꢀheatedꢀ
toꢀ403ꢀKꢀtoꢀeliminateꢀmoisture.ꢀThenꢀtheꢀsampleꢀwasꢀreducedꢀ
inꢀ aꢀ 10%ꢀ H
2
/Arꢀ flowꢀ atꢀ 40ꢀ mL/minꢀ fromꢀ 323ꢀ toꢀ 773ꢀ Kꢀ atꢀ aꢀ
Inꢀtheꢀpresentꢀstudy,ꢀweꢀpreparedꢀIr‐Re/SiO
SiO ꢀ pretreatedꢀ byꢀ C1–C4ꢀ normalꢀ alcohols.ꢀ Theꢀ catalyticꢀ per‐
formancesꢀ ofꢀ theꢀ alcohol‐pretreatedꢀ SiO ꢀ supportedꢀ catalystsꢀ
2
ꢀcatalystsꢀwithꢀ
heatingꢀ rateꢀ ofꢀ 10ꢀ K/min.ꢀ H
AMI‐300ꢀ catalystꢀ characterizationꢀ system.ꢀ 100ꢀ mgꢀ ofꢀ catalystꢀ
wasꢀheatedꢀtoꢀ773ꢀKꢀforꢀ1hꢀinꢀanꢀargonꢀflow.ꢀThenꢀtheꢀsampleꢀ
2
‐TPDꢀ wasꢀ carriedꢀ outꢀ onꢀ anꢀ
2
2
forꢀglycerolꢀhydrogenolysisꢀtoꢀ1,3‐propanediolꢀwasꢀtestedꢀandꢀ
comparedꢀ withꢀ theꢀ catalystꢀ preparedꢀ usingꢀ non‐pretreatedꢀ
wasꢀreducedꢀinꢀaꢀ10%ꢀH /Arꢀflowꢀatꢀ443ꢀKꢀforꢀ2ꢀh,ꢀandꢀcooledꢀ
2
downꢀtoꢀ303ꢀKꢀafterꢀholdingꢀforꢀ1ꢀh.ꢀAfterꢀthat,ꢀtheꢀhydrogenꢀinꢀ
theꢀsystemꢀwasꢀreplacedꢀbyꢀargonꢀtoꢀconductꢀtheꢀTPDꢀexperi‐
ment.ꢀTheꢀheatingꢀrateꢀwasꢀkeptꢀatꢀ10ꢀK/min,ꢀandꢀtheꢀflowꢀrateꢀ
ofꢀargonꢀwasꢀ30ꢀmL/min.ꢀH2ꢀchemisorptionꢀwasꢀperformedꢀonꢀ
anꢀAMI‐300ꢀcatalystꢀcharacterizationꢀsystem.ꢀAboutꢀ100ꢀmgꢀofꢀ
SiO .ꢀSupportꢀpretreatmentꢀincreasedꢀtheꢀdispersionꢀofꢀiridium.ꢀ
2
Theꢀcarbonꢀchainꢀlengthꢀofꢀtheꢀalcoholꢀusedꢀforꢀtheꢀpretreat‐
mentꢀinfluencedꢀtheꢀsurfaceꢀpropertiesꢀofꢀtheꢀsupportꢀandꢀhasꢀ
anꢀimpactꢀonꢀtheꢀdispersionꢀofꢀIrꢀspecies.ꢀ
theꢀcatalystꢀsampleꢀwasꢀreducedꢀinꢀaꢀflowꢀofꢀ10%ꢀH
Kꢀforꢀ2ꢀh,ꢀthenꢀpurgedꢀbyꢀargonꢀatꢀtheꢀsameꢀtemperatureꢀforꢀ0.5ꢀ
h,ꢀandꢀfinallyꢀcooledꢀdownꢀtoꢀ313ꢀK.ꢀUptakeꢀofꢀH ꢀwasꢀmeasuredꢀ
byꢀinjectingꢀ10%ꢀH /Arꢀintoꢀtheꢀargonꢀcarrierꢀgasꢀinꢀaꢀpulsedꢀ
mode.ꢀ Temperatureꢀ programmedꢀ desorptionꢀ ofꢀ ammoniaꢀ
(NH ‐TPD)ꢀwasꢀcarriedꢀoutꢀonꢀanꢀAMI‐300ꢀcatalystꢀcharacteri‐
2
/Arꢀatꢀ443ꢀ
2
.ꢀ ꢀ Experimentalꢀ
2
2.1.ꢀ ꢀ Catalystꢀpreparationꢀ
2
Silicaꢀgelꢀ(QingdaoꢀHaiyangꢀChemicalsꢀCo.)ꢀwasꢀdriedꢀatꢀ383ꢀ
3
Kꢀforꢀ4ꢀh,ꢀandꢀthenꢀusedꢀasꢀtheꢀsupportꢀwhichꢀisꢀdenotedꢀasꢀSꢀ
here.ꢀ Forꢀ theꢀ supportꢀ pretreatment,ꢀ theꢀ silicaꢀ gelꢀ (2ꢀ g)ꢀ wasꢀ
treatedꢀwithꢀ5ꢀmLꢀeachꢀofꢀtheꢀC1ꢀtoꢀC4ꢀnormalꢀalcoholsꢀbyꢀim‐
pregnation.ꢀTheꢀresultantꢀsilicaꢀgelꢀwasꢀdriedꢀatꢀ383ꢀKꢀforꢀ4ꢀhꢀ
afterꢀpreliminaryꢀdryingꢀunderꢀambientꢀconditions.ꢀTheseꢀwereꢀ
denotedꢀasꢀS‐Cnꢀ(n=1–4,ꢀnꢀisꢀtheꢀcarbonꢀnumberꢀofꢀalcohol).ꢀ
Ir‐Re/S‐Cnꢀ(n=1–4)ꢀwasꢀpreparedꢀbyꢀco‐impregnationꢀwithꢀ
zationꢀsystem.ꢀAꢀ100ꢀmgꢀsampleꢀwasꢀused.ꢀPriorꢀtoꢀeachꢀmeas‐
urement,ꢀaꢀsampleꢀwasꢀpretreatedꢀinꢀanꢀargonꢀflowꢀatꢀ873ꢀKꢀforꢀ
0.5ꢀh.ꢀAfterꢀcoolingꢀtoꢀ373ꢀKꢀinꢀaꢀcontinuousꢀflowꢀofꢀargon,ꢀtheꢀ
sampleꢀadsorbedꢀNH ꢀusingꢀtheꢀstaticꢀadsorptionꢀmethodꢀuntilꢀ
3
saturation.ꢀThenꢀtheꢀsampleꢀwasꢀheatedꢀfromꢀ373ꢀtoꢀ873ꢀKꢀwithꢀ
aꢀrampꢀofꢀ10ꢀ K/minꢀinꢀ aꢀheliumꢀflowꢀofꢀ30ꢀ mL/minꢀandꢀtheꢀ
desorbedꢀNH ꢀwasꢀmonitoredꢀsimultaneouslyꢀwithꢀTCD.ꢀ ꢀ
3
aqueousꢀsolutionsꢀofꢀH
2
IrCl6ꢀ(TianjinꢀFengchuanꢀChemicalꢀRea‐
Theꢀ acidityꢀ ofꢀ theꢀ catalystꢀ wasꢀ analyzedꢀ byꢀ FT‐IRꢀ ofꢀ ad‐
sorbedꢀ pyridineꢀ usingꢀ aꢀ Thermoꢀ Scientificꢀ Nicoletꢀ iS50ꢀ FT‐IRꢀ
spectrometerꢀequippedꢀwithꢀaꢀDTGSꢀdetector.ꢀ10ꢀmgꢀofꢀaꢀsam‐
pleꢀwasꢀpressedꢀintoꢀaꢀself‐supportingꢀwaferꢀfollowedꢀbyꢀevac‐
uationꢀatꢀ773ꢀKꢀforꢀ1ꢀh.ꢀAfterꢀcoolingꢀdownꢀtoꢀroomꢀtempera‐
ture,ꢀtheꢀbackgroundꢀspectrumꢀwasꢀrecorded.ꢀTheꢀsampleꢀwasꢀ
exposedꢀtoꢀpyridineꢀforꢀ5ꢀmin.ꢀAfterꢀthatꢀtheꢀcatalystꢀwasꢀheat‐
edꢀatꢀaꢀlinearꢀrateꢀofꢀ10ꢀK/minꢀtoꢀ323,ꢀ523ꢀandꢀ623ꢀK,ꢀrespec‐
tively,ꢀ andꢀ keptꢀ forꢀ 0.5ꢀ hꢀ atꢀ eachꢀ temperatureꢀ underꢀ vacuumꢀ
conditionsꢀ (10ꢀ mPa).ꢀ Inꢀ situꢀ FT‐IRꢀ spectraꢀ ofꢀ COꢀ adsorptionꢀ
wereꢀ recordedꢀ aꢀ Thermoꢀ Scientificꢀ Nicoletꢀ iS50ꢀ FT‐IRꢀ spec‐
trometerꢀequippedꢀwithꢀaꢀDTGSꢀdetector.ꢀBeforeꢀcharacteriza‐
tion,ꢀtheꢀsampleꢀ(aboutꢀ10ꢀmgꢀspentꢀcatalyst)ꢀwasꢀcompressedꢀ
gentꢀCo.,ꢀLtd)ꢀandꢀNH
4
ReO ꢀ(ZhuzhouꢀJinlaiꢀIndustryꢀCo.,ꢀLtd)ꢀ
4
simultaneouslyꢀ ofꢀ theꢀ supportꢀ pretreatedꢀ withꢀ alcohol.ꢀ Thisꢀ
wasꢀfollowedꢀbyꢀdryingꢀatꢀ393ꢀKꢀforꢀ12ꢀhꢀandꢀcalciningꢀatꢀ773ꢀKꢀ
forꢀ3ꢀh.ꢀIr‐Re/Sꢀwasꢀpreparedꢀbyꢀusingꢀnon‐treatedꢀsilica.ꢀTheꢀ
otherꢀ proceduresꢀ wereꢀ theꢀ sameꢀ asꢀ thatꢀ ofꢀ theꢀ Ir‐Re/S‐Cnꢀ
(n=1–4)ꢀcatalysts.ꢀBothꢀofꢀtheꢀcontentsꢀofꢀiridiumꢀandꢀrheniumꢀ
wereꢀ2ꢀwt%.ꢀAllꢀchemicalsꢀusedꢀwereꢀanalyticalꢀreagent.ꢀ
2.2.ꢀ ꢀ Characterizationꢀ
Nitrogenꢀadsorptionꢀisothermsꢀofꢀtheꢀcatalystꢀsamplesꢀwereꢀ
measuredꢀ atꢀ 77ꢀ Kꢀ withꢀ anꢀ Autosorb‐iQꢀ adsorptionꢀ analyzerꢀ
Quantachrome).ꢀTheꢀspecificꢀsurfaceꢀareaꢀofꢀtheꢀsamplesꢀwasꢀ
(
intoꢀ aꢀ self‐supportingꢀ discꢀ andꢀ reducedꢀ inꢀ aꢀ H
2
ꢀ flowꢀ ofꢀ ꢀ ꢀ ꢀ ꢀ ꢀ ꢀ
calculatedꢀbyꢀtheꢀBrunauer‐Emmett‐Tellerꢀ(BET)ꢀmethod.ꢀTheꢀ
totalꢀ poreꢀ volumeꢀ ofꢀ theꢀ samplesꢀ wasꢀ calculatedꢀ fromꢀ theꢀ
amountꢀadsorbedꢀatꢀaꢀrelativeꢀpressureꢀp/p0ꢀ=ꢀ0.995.ꢀ
Fourierꢀ transformꢀ infraredꢀ (FT‐IR)ꢀ spectraꢀ wereꢀ obtainedꢀ
usingꢀ aꢀ Thermoꢀ Scientificꢀ Nicoletꢀ iS50ꢀ FT‐IRꢀ spectrometerꢀ
equippedꢀwithꢀaꢀDTGSꢀdetector.ꢀTheꢀsampleꢀwasꢀheatedꢀtoꢀ473ꢀ
Kꢀ forꢀ 1ꢀ hꢀ inꢀ vacuum.ꢀ Spectraꢀ wereꢀ collectedꢀ inꢀ theꢀ rangeꢀ ofꢀ
40ꢀmL/minꢀatꢀ523K.ꢀTheꢀsampleꢀwasꢀheatedꢀinꢀvacuumꢀforꢀ1ꢀhꢀ
atꢀ773ꢀK,ꢀandꢀthenꢀcooledꢀdownꢀtoꢀroomꢀtemperature,ꢀatꢀwhichꢀ
pointꢀ aꢀ backgroundꢀ spectrumꢀ wasꢀ acquired.ꢀ Theꢀ sampleꢀ wasꢀ
thenꢀexposedꢀtoꢀCOꢀflow.ꢀAfterꢀ30ꢀmin,ꢀtheꢀcellꢀwasꢀevacuatedꢀ
toꢀremoveꢀphysisorbedꢀandꢀgasꢀphaseꢀCO.ꢀThenꢀtheꢀspectraꢀofꢀ
COꢀchemisorptionꢀonꢀtheꢀsampleꢀwereꢀtaken.ꢀAllꢀtheꢀgasesꢀusedꢀ
inꢀ characterizationꢀ wereꢀ analyticalꢀ reagentꢀ fromꢀ Guangmingꢀ
Researchꢀ&ꢀDesignꢀInstituteꢀofꢀChemicalꢀIndustry.ꢀ
–1
–1
2
400–4000ꢀcm ꢀwithꢀ4ꢀcm ꢀresolution.ꢀ
PowderꢀX‐rayꢀdiffractionꢀ(XRD)ꢀanalysisꢀwasꢀperformedꢀonꢀ
anꢀX’pertꢀPRO/PANalyticalꢀdiffractometerꢀusingꢀCuꢀK
α
ꢀradiationꢀ
2.3.ꢀ ꢀ Catalyticꢀactivityꢀmeasurementsꢀ
andꢀoperatedꢀatꢀ40ꢀkVꢀandꢀ40ꢀmA.ꢀTheꢀXRDꢀpatternsꢀwereꢀrec‐
ordedꢀ forꢀ 2θꢀ valuesꢀ fromꢀ 10°ꢀ toꢀ 80°.ꢀ Theꢀ scanningꢀ rateꢀ wasꢀ
Theꢀ glycerolꢀ hydrogenolysisꢀ reactionꢀ wasꢀ performedꢀ inꢀ aꢀ
trickleꢀbedꢀreactorꢀ(9ꢀmmꢀi.d.)ꢀusingꢀ1.5ꢀgꢀcatalyst.ꢀTheꢀhydro‐
genꢀflowꢀwasꢀ40ꢀmL/minꢀwhichꢀcorrespondedꢀtoꢀaꢀspaceꢀveloc‐
ityꢀofꢀ1600ꢀmL/(h·g).ꢀTheꢀglycerolꢀaqueousꢀflowꢀwasꢀ0.65ꢀmL/hꢀ
whichꢀcorrespondedꢀtoꢀaꢀspaceꢀvelocityꢀofꢀ0.44ꢀmL/(h·g).ꢀBe‐
1
4°/min.ꢀ TEMꢀ measurementsꢀ wereꢀ carriedꢀ outꢀ usingꢀ aꢀ
JEM‐2100ꢀ microscopeꢀ operatedꢀ atꢀ anꢀ acceleratingꢀ voltageꢀ ofꢀ
00ꢀ kV.ꢀ Theꢀ spentꢀ catalystꢀ wasꢀ suspendedꢀ inꢀ ethanolꢀ andꢀ
2
placedꢀontoꢀaꢀcarbonꢀfilmꢀsupportedꢀoverꢀaꢀcopperꢀgrid.ꢀ
Temperatureꢀprogrammedꢀreductionꢀ(TPR)ꢀwasꢀperformedꢀ
foreꢀreaction,ꢀtheꢀcatalystꢀwasꢀreducedꢀatꢀ443ꢀKꢀinꢀH
ꢀflowꢀofꢀ40ꢀ
2

ꢀ
WentingꢀLuoꢀetꢀal.ꢀ/ꢀChineseꢀJournalꢀofꢀCatalysisꢀ37ꢀ(2016)ꢀ2009–2017ꢀ
2011ꢀ
mL/minꢀatꢀatmosphereꢀpressure.ꢀTheꢀreactionꢀwasꢀconductedꢀ
atꢀ403ꢀKꢀandꢀ8ꢀMPa.ꢀTheꢀgaseousꢀproductsꢀfromꢀtheꢀeffluentꢀ
wereꢀ analyzedꢀ onlineꢀ usingꢀ anꢀ Agilentꢀ GC‐7890ꢀ chromato‐
graph.ꢀTheꢀliquidꢀphaseꢀproductsꢀwereꢀquantifiedꢀbyꢀanꢀinter‐
nalꢀ standardꢀ method,ꢀ andꢀ theꢀ internalꢀ standardꢀ wasꢀ n‐butylꢀ
alcohol.ꢀThen,ꢀtheꢀliquidꢀphaseꢀproductsꢀwereꢀesterifiedꢀbyꢀace‐
ticꢀanhydrideꢀcatalyzedꢀbyꢀpyridineꢀ(TianjinꢀKemiouꢀChemicalꢀ
Reagentꢀ Co.ꢀ Ltd)ꢀ andꢀ heatedꢀ toꢀ 328ꢀ Kꢀ forꢀ 1.5ꢀ h.ꢀ Theꢀ volumeꢀ
ratioꢀofꢀaceticꢀanhydrideꢀandꢀpyridineꢀisꢀ2:1.ꢀTheꢀsamplesꢀwereꢀ
quantifiedꢀonꢀaꢀgasꢀchromatographꢀ(Agilentꢀ7890)ꢀfittedꢀwithꢀaꢀ
flameꢀ ionizationꢀ detectorꢀ andꢀ aꢀ HP‐5ꢀ capillaryꢀ column.ꢀ Theꢀ
conversionꢀofꢀglycerolꢀandꢀtheꢀselectivityꢀtoꢀtheꢀproductsꢀwereꢀ
calculatedꢀbyꢀtheꢀfollowingꢀequations:ꢀ
Conversionꢀ ofꢀ glycerolꢀ (%)ꢀ =ꢀ (molesꢀ ofꢀ glycerolꢀ initiallyꢀ
addedꢀ–ꢀmolesꢀofꢀglycerolꢀthatꢀremained)ꢀ/ꢀmolesꢀofꢀglycerolꢀ
initiallyꢀaddedꢀ×ꢀ100ꢀ ꢀ
Selectivityꢀ(%)ꢀ=ꢀCꢀmoleꢀofꢀspecificꢀproductꢀ/ꢀsumꢀofꢀCꢀmoleꢀ
ofꢀglycerolꢀconsumedꢀ×ꢀ100ꢀ
Theꢀremovalꢀselectivityꢀofꢀprimaryꢀ(orꢀsecondary)ꢀhydroxylꢀ
groupꢀ(%)ꢀ(S1‐OHꢀorꢀS2‐OH)ꢀ=ꢀsumꢀofꢀremovalꢀprimaryꢀorꢀsecond‐
aryꢀhydroxylꢀgroupꢀ/ꢀsumꢀofꢀremovalꢀhydroxylꢀgroupꢀ×ꢀ100ꢀ
Theꢀyieldꢀofꢀremovalꢀsecondaryꢀhydroxylꢀgroupꢀ(Y2‐OH,ꢀ%)ꢀ=ꢀ
Conversionꢀ ofꢀ glycerolꢀ ×ꢀ removalꢀ selectivityꢀ ofꢀ secondaryꢀ hy‐
droxylꢀgroupꢀ
Tableꢀ1ꢀ
SpecificꢀsurfaceꢀareaꢀandꢀporeꢀvolumeꢀofꢀuntreatedꢀandꢀpretreatedꢀSiO2.
S
(m
BET
ꢀ
Poreꢀvolumeꢀ Massꢀlossꢀ Moleꢀofꢀalcoholꢀmoleculeꢀ
Sample
2
3
(%)ꢀaꢀ
/g)
(cm
/g)ꢀ
(0.1ꢀmmol/g)ꢀ
S
ꢀ
426.8ꢀ
257.4ꢀ
282.2ꢀ
305.8ꢀ
291.2ꢀ
1.24ꢀ
0.98ꢀ
1.04ꢀ
1.14ꢀ
1.08ꢀ
—ꢀ
—ꢀ
1.2ꢀ
1.5ꢀ
0.9ꢀ
—ꢀ
—ꢀ
2.6ꢀ
2.5ꢀ
1.2ꢀ
S‐C1ꢀ
S‐C2ꢀ
S‐C3ꢀ
S‐C4ꢀ
aꢀResultsꢀfromꢀthermogravimetricꢀanalysis.ꢀ
ꢀ
centꢀSi–OHꢀincreasedꢀforꢀtheꢀpretreatedꢀSiO .ꢀ
2
Theꢀ specificꢀ surfaceꢀ areaꢀ andꢀ poreꢀ volumeꢀ obtainedꢀ fromꢀ
theꢀnitrogenꢀadsorptionꢀisothermsꢀareꢀshownꢀinꢀTableꢀ1.ꢀTheꢀ
specificꢀ surfaceꢀ areaꢀ andꢀ poreꢀ volumeꢀ ofꢀ theꢀ pretreatedꢀ SiO
wereꢀlessꢀthanꢀthoseꢀofꢀtheꢀuntreatedꢀone.ꢀThisꢀmayꢀresultꢀfromꢀ
theꢀgraftingꢀofꢀalkoxylꢀgroupsꢀinꢀtheꢀporesꢀofꢀtheꢀSiO ꢀsupport.ꢀ
2
ꢀ
2
Withꢀtheꢀincreaseꢀofꢀcarbonꢀnumberꢀinꢀtheꢀalcoholꢀmolecules,ꢀ
bothꢀtheꢀspecificꢀsurfaceꢀareaꢀandꢀporeꢀvolumeꢀincreasedꢀfirstꢀ
andꢀthenꢀdecreasedꢀaꢀlittle.ꢀTheꢀmaximumꢀwasꢀobtainedꢀforꢀtheꢀ
S‐C3ꢀ support.ꢀ Theꢀ reasonꢀ whyꢀ theꢀ specificꢀ surfaceꢀ areaꢀ andꢀ
poreꢀ volumeꢀ ofꢀ S‐C3ꢀ andꢀ S‐C4ꢀ wereꢀ largerꢀ thanꢀ thoseꢀ ofꢀ theꢀ
smallerꢀalcoholsꢀmayꢀbeꢀdueꢀtoꢀthatꢀtheꢀnumberꢀofꢀgraftedꢀal‐
coholꢀmoleculesꢀofꢀS‐C1ꢀandꢀS‐C2ꢀwereꢀlarger,ꢀwhichꢀwasꢀcon‐
sistentꢀ withꢀ theꢀ thermogravimetricꢀ analysisꢀ resultsꢀ shownꢀ inꢀ
Tableꢀ 1.ꢀ Whenꢀ theꢀ supportꢀ wasꢀ treatedꢀ withꢀ C2–C4ꢀ alcohols,ꢀ
theꢀmolesꢀofꢀalcoholꢀmoleculeꢀadsorbedꢀdecreasedꢀasꢀtheꢀcar‐
bonꢀnumberꢀincreased.ꢀ ꢀ
3.ꢀ ꢀ Resultsꢀandꢀdiscussionꢀ
3.1.ꢀ ꢀ Characterizationꢀofꢀtheꢀsupportꢀpretreatedꢀwithꢀdifferentꢀ
alcoholsꢀ
3
.2.ꢀ ꢀ Characterizationꢀofꢀtheꢀalcohol‐pretreatedꢀSiO
2
ꢀsupportedꢀ
catalystsꢀ
AsꢀshownꢀinꢀFig.ꢀ1,ꢀtheꢀbroadꢀbandꢀbetweenꢀ3100ꢀandꢀ3700ꢀ
–1
cm ꢀwasꢀattributedꢀtoꢀtheꢀhydrogen‐bondedꢀSi–OHꢀstretchingꢀ
TheꢀTPRꢀprofilesꢀofꢀtheꢀcatalystsꢀareꢀshownꢀinꢀFig.ꢀ2.ꢀInꢀtheꢀ
caseꢀofꢀRe/S,ꢀaꢀsingleꢀreductionꢀpeakꢀatꢀ583ꢀKꢀwasꢀobserved.ꢀInꢀ
theꢀTPRꢀprofileꢀofꢀIr/S,ꢀtheꢀreductionꢀpeakꢀatꢀ493ꢀKꢀcanꢀbeꢀas‐
signedꢀ toꢀ theꢀ reductionꢀ ofꢀ iridium.ꢀ Comparedꢀ withꢀ theꢀ TPRꢀ
profilesꢀofꢀRe/SꢀandꢀIr/S,ꢀobviousꢀshiftsꢀofꢀtheꢀreductionꢀtem‐
peratureꢀ towardsꢀ lowerꢀ temperatureꢀ wereꢀ observedꢀ onꢀ theꢀ
Ir‐Re/Sꢀcatalysts.ꢀItꢀisꢀknownꢀthatꢀtheꢀadditionꢀofꢀReꢀimprovedꢀ
–1
vibrations.ꢀTheꢀpeakꢀcenteredꢀatꢀ3743ꢀcm ꢀwasꢀattributedꢀtoꢀ
theꢀisolatedꢀSi–OHꢀstretchingꢀvibrations.ꢀTheꢀabsorptionꢀbandsꢀ
–1
atꢀ2800ꢀtoꢀ3000ꢀcm ꢀwereꢀassignedꢀtoꢀtheꢀCHꢀstretchingꢀvi‐
brationsꢀofꢀsurfaceꢀalkoxylꢀgroupsꢀ[22,29–32].ꢀObviousꢀabsorp‐
tionꢀ bandsꢀ correspondingꢀ toꢀ alkoxylꢀ groupsꢀ appearedꢀ onꢀ theꢀ
pretreatedꢀSiO
graftedꢀontoꢀtheꢀsilicaꢀsurfaceꢀbyꢀreactingꢀwithꢀtheꢀSi–OHꢀafterꢀ
theꢀSiO ꢀpretreatment.ꢀInꢀaddition,ꢀtheꢀratioꢀofꢀisolatedꢀtoꢀadja‐
2
,ꢀwhichꢀsuggestedꢀthatꢀalcoholꢀmoleculesꢀwereꢀ
theꢀ dispersionꢀ ofꢀ Irꢀ speciesꢀ [8].ꢀ Smallerꢀ IrO ꢀ particlesꢀ onꢀ theꢀ
Ir‐Reꢀ catalystsꢀ areꢀ moreꢀ easilyꢀ reduced,ꢀ andꢀ thenꢀ byꢀ theꢀ hy‐
2
2
2963
3743
583
S-C4
S-C3
Re/SiO2
493
Ir/SiO2
4
02
4
35
Ir-Re/S
S-C2
S-C1
4
21
385
457
Ir-Re/S-C4
Ir-Re/S-C3
Ir-Re/S-C2
Ir-Re/S-C1
S
3
800 3600 3400 3200 3000 2800 2600
400
500
600
700
1
Wavenumber (cm )
Temperature (K)
Fig.ꢀ 1.ꢀ FT‐IRꢀ spectraꢀ ofꢀ SiO
catalysts.ꢀ
2
ꢀ andꢀ alcohol‐pretreatedꢀ SiO ꢀ supportedꢀ
2
Fig.ꢀ2. H
2
‐TPRꢀprofilesꢀofꢀalcohol‐pretreatedꢀSiO ꢀsupportedꢀcatalysts.
2

2012ꢀ
WentingꢀLuoꢀetꢀal.ꢀ/ꢀChineseꢀJournalꢀofꢀCatalysisꢀ37ꢀ(2016)ꢀ2009–2017ꢀ
drogenꢀ spilloverꢀ mechanism,ꢀ migrationꢀ ofꢀ theꢀ dissociatedꢀ hy‐
drogenꢀfromꢀIrO ꢀtoꢀReꢀoxideꢀresultedꢀinꢀtheꢀimprovementꢀofꢀ
theꢀreductionꢀofꢀReꢀoxide,ꢀsoꢀtheꢀreductionꢀtemperatureꢀshiftedꢀ
towardꢀlowerꢀtemperature.ꢀTheꢀTPRꢀprofileꢀofꢀIr‐Re/Sꢀshowedꢀ
twoꢀ broadꢀ peaks,ꢀ butꢀ theꢀ reductionꢀ profileꢀ ofꢀ theꢀ alco‐
licꢀiridiumꢀ(PDFꢀ01‐087‐0715).ꢀForꢀbothꢀtheꢀfreshꢀorꢀspentꢀcat‐
alysts,ꢀ aꢀ peakꢀ dueꢀ toꢀ Reꢀ speciesꢀ wasꢀ notꢀ detected,ꢀ indicatingꢀ
thatꢀtheꢀReꢀspeciesꢀwasꢀhighlyꢀdispersed.ꢀ ꢀ
Fig.ꢀ5ꢀdisplaysꢀtheꢀTEMꢀimagesꢀofꢀtheꢀspentꢀcatalysts.ꢀTheꢀIrꢀ
speciesꢀandꢀReꢀspeciesꢀwereꢀhardꢀtoꢀdistinguishꢀbyꢀtheꢀlatticeꢀ
fringes.ꢀButꢀtheseꢀvisibleꢀparticlesꢀwereꢀthoughtꢀtoꢀbeꢀIrꢀspeciesꢀ
becauseꢀtheꢀReꢀspeciesꢀparticlesꢀwereꢀsoꢀsmallꢀthatꢀtheyꢀwouldꢀ
beꢀdifficultꢀtoꢀobserveꢀaccordingꢀtoꢀtheꢀresultsꢀofꢀXRDꢀ[8].ꢀTheꢀIrꢀ
averageꢀparticleꢀsizeꢀcalculatedꢀstatisticallyꢀbyꢀTEMꢀareꢀshownꢀ
inꢀTableꢀ3.ꢀItꢀwasꢀfoundꢀthatꢀtheꢀpretreatedꢀsupportsꢀbenefitedꢀ
2
hol‐pretreatedꢀ SiO
threeꢀreductionꢀpeaks.ꢀTheꢀreductionꢀstartedꢀatꢀlowerꢀtemper‐
atureꢀonꢀtheꢀalcohol‐pretreatedꢀSiO ꢀsupportedꢀcatalysts,ꢀwhichꢀ
2
ꢀ supportedꢀ catalystsꢀ wasꢀ characterizedꢀ byꢀ
2
suggestedꢀ thatꢀ smallerꢀ Irꢀ speciesꢀ particlesꢀ wereꢀ formedꢀ onꢀ
theseꢀ catalysts.ꢀ Theꢀ lowꢀ temperatureꢀ reductionꢀ peakꢀ wasꢀ ob‐
2
servedꢀatꢀ385ꢀKꢀonꢀtheꢀalcohol‐pretreatedꢀSiO ꢀsupportedꢀcata‐
theꢀdispersionꢀofꢀIrꢀandꢀallꢀofꢀtheꢀalcohol‐pretreatedꢀSiO
2
ꢀsup‐
lystsꢀandꢀ402ꢀKꢀonꢀIr‐Re/S,ꢀwhichꢀwasꢀassignedꢀtoꢀtheꢀreductionꢀ
ofꢀIrꢀspecies.ꢀTheꢀsubsequentꢀreductionꢀpeakꢀatꢀ421ꢀorꢀ435ꢀKꢀ
wasꢀattributedꢀtoꢀtheꢀco‐reductionꢀofꢀIrꢀandꢀReꢀoxideꢀspecies.ꢀ
Theꢀhighꢀtemperatureꢀpeakꢀthatꢀonlyꢀexistedꢀonꢀtheꢀpretreatedꢀ
portedꢀ catalystsꢀ showedꢀ aꢀ smallerꢀ Irꢀ averageꢀ particleꢀ size.ꢀ
Ir‐Re/S‐C3ꢀpresentedꢀtheꢀsmallestꢀIrꢀparticles.ꢀTheꢀTEMꢀresultsꢀ
wereꢀconsistentꢀwithꢀthatꢀofꢀtheꢀXRDꢀmeasurements.ꢀ
InꢀtheꢀH
respondsꢀtoꢀtheꢀadsorptionꢀstrength.ꢀForꢀallꢀtheseꢀcatalysts,ꢀoneꢀ
weakꢀH ꢀdesorptionꢀpeakꢀwasꢀobservedꢀatꢀ350ꢀK,ꢀindicatingꢀaꢀ
2
‐TPDꢀprofilesꢀ(Fig.ꢀ6),ꢀtheꢀpositionꢀofꢀtheꢀpeakꢀcor‐
catalystsꢀatꢀ457ꢀKꢀmayꢀbeꢀdueꢀtoꢀtheꢀreductionꢀofꢀIrO
2
ꢀorꢀReꢀ
oxideꢀ speciesꢀ withꢀ aꢀ strongerꢀ interactionꢀ withꢀ theꢀ supportꢀ
2
4+
0
[
33,34].ꢀIfꢀallꢀIr ꢀwasꢀsupposedꢀtoꢀbeꢀreducedꢀtoꢀIr ,ꢀtheꢀvalenceꢀ
ofꢀ theꢀ Reꢀ speciesꢀ canꢀ beꢀ calculatedꢀ byꢀ theꢀ H ꢀ consumption,ꢀ
whichꢀ isꢀ summarizedꢀ inꢀ Tableꢀ 2.ꢀ Theꢀ Reꢀ valenceꢀ ofꢀ theꢀ alco‐
hol‐pretreatedꢀ SiO ꢀ supportedꢀ catalystsꢀ andꢀ untreatedꢀ oneꢀ
wereꢀapproximatelyꢀ4.5,ꢀbutꢀthatꢀonꢀRe/Sꢀwasꢀmeasuredꢀtoꢀbeꢀ
.7.ꢀThisꢀindicatedꢀthatꢀtheꢀReꢀspeciesꢀhasꢀanꢀinteractionꢀwithꢀIrꢀ
weakꢀadsorptionꢀofꢀhydrogenꢀonꢀtheꢀsurfaceꢀofꢀmetallicꢀIr.ꢀButꢀ
whenꢀtheꢀcarbonꢀnumberꢀofꢀtheꢀalcoholꢀincreasedꢀfromꢀ1ꢀtoꢀ3,ꢀ
theꢀstrengthꢀofꢀhydrogenꢀadsorptionꢀincreasedꢀaꢀlittleꢀandꢀthenꢀ
decreasedꢀwhenꢀtheꢀcarbonꢀnumberꢀincreased.ꢀIntegratingꢀtheꢀ
desorptionꢀpeakꢀarea,ꢀtheꢀamountsꢀofꢀdesorbedꢀhydrogenꢀwereꢀ
obtained,ꢀwhichꢀareꢀlistedꢀinꢀTableꢀ4.ꢀTheꢀdesorptionꢀamountsꢀ
2
2
2
speciesꢀorꢀtheꢀsupportꢀinꢀtheꢀIr‐Reꢀcatalysts.ꢀ
ofꢀ H
whenꢀtheꢀsupportꢀwasꢀpretreatedꢀwithꢀalcohol.ꢀTheꢀdesorptionꢀ
amountsꢀofꢀH ꢀwereꢀsimilarꢀforꢀallꢀtheꢀalcohol‐pretreatedꢀSiO
supportedꢀ catalysts.ꢀ Theꢀ dispersionꢀ ofꢀ Irꢀ onꢀ theseꢀ catalysts,ꢀ
whichꢀwasꢀcalculatedꢀassumingꢀoneꢀhydrogenꢀmoleculeꢀdisso‐
ciativelyꢀadsorbedꢀonꢀtwoꢀIrꢀatoms,ꢀshowedꢀtheꢀsameꢀtrendꢀasꢀ
2
ꢀ onꢀ Ir‐Re/Sꢀ catalystꢀ wasꢀ 4.9ꢀ μmol/g,ꢀ andꢀ thisꢀ increasedꢀ
Fig.ꢀ3ꢀshowsꢀtheꢀXRDꢀpatternsꢀofꢀtheꢀfreshꢀcatalysts.ꢀTheꢀdif‐
fractionꢀpeakꢀatꢀ2θꢀ=ꢀ21.4°ꢀwasꢀattributedꢀtoꢀamorphousꢀsilicaꢀ
gel.ꢀ Theꢀ diffractionꢀ peaksꢀ atꢀ 26.7°(110),ꢀ 34.2°(101)ꢀ andꢀ
2
2
ꢀ
5
3.1°(211)ꢀcanꢀbeꢀreadilyꢀindexedꢀtoꢀIrO ꢀ(PDFꢀ01‐088‐0288).ꢀ
2
AsꢀshownꢀinꢀFig.ꢀ4,ꢀaꢀdiffusedꢀdiffractionꢀpeakꢀatꢀ2θꢀ=ꢀ40.5°ꢀwasꢀ
observedꢀonꢀtheꢀspentꢀcatalysts,ꢀwhichꢀcorrespondedꢀtoꢀmetal‐
2
theꢀdesorptionꢀamountsꢀofꢀH .ꢀTheꢀdispersionꢀcalculatedꢀbyꢀtheꢀ
TEMꢀresultsꢀ(Tableꢀ3)ꢀwasꢀmuchꢀhigherꢀthanꢀfromꢀH
2
‐TPD,ꢀandꢀ
theꢀ amountsꢀ ofꢀ exposedꢀ activeꢀ metallicꢀ Irꢀ wasꢀ onlyꢀ approxi‐
matelyꢀ 32.5%ꢀ ofꢀ thatꢀ calculatedꢀ withꢀ theꢀ TEMꢀ results.ꢀ Thisꢀ
Tableꢀ2ꢀ
TPRꢀresultsꢀofꢀdifferentꢀsamples.ꢀ
suggestedꢀthatꢀIrꢀmightꢀbeꢀcoveredꢀbyꢀReꢀspeciesꢀbecauseꢀReO
cannotꢀadsorbꢀhydrogen.ꢀWeꢀcalculatedꢀtheꢀmolesꢀofꢀIrꢀcoveredꢀ
byꢀReO ꢀusingꢀtheꢀresultsꢀofꢀTEMꢀandꢀH ‐TPD,ꢀandꢀtheꢀdataꢀareꢀ
listedꢀinꢀTableꢀ4.ꢀItꢀwasꢀfoundꢀthatꢀsuperficialꢀIrꢀatomsꢀonꢀtheꢀ
Ir‐Re/S‐C3ꢀcatalystꢀwereꢀtheꢀmostꢀcoveredꢀamongꢀallꢀtheꢀcata‐
lysts.ꢀ
x
ꢀ
Catalystꢀ
Ir‐Re/Sꢀ
Ir‐Re/S‐C1ꢀ
Ir‐Re/S‐C2ꢀ
Ir‐Re/S‐C3ꢀ
Ir‐Re/S‐C4ꢀ
H
2
ꢀconsumptionꢀ(μmol/g)ꢀ
Reꢀvalenceꢀ
4.6ꢀ
337.2ꢀ
333.2ꢀ
338.1ꢀ
346.8ꢀ
338.3ꢀ
228.1ꢀ
x
2
4.6ꢀ
4.6ꢀ
4.4ꢀ
4.5ꢀ
Re/S
ꢀ
2.7ꢀ
◆
◆
▼
IrO2 ◆ SiO2
▼
▼Ir ◆ SiO2
▼
▼
▼
Ir-Re/S-C4
Ir-Re/S-C4
Ir-Re/S-C3
Ir-Re/S-C3
Ir-Re/S-C2
Ir-Re/S-C1
Ir-Re/S-C2
Ir-Re/S-C1
Ir-Re/S
Ir-Re/S
10
20
30
40
2
50
)
60
70
80
10
20
30
40
2
50
60
70
80
o
o
 / (
 / (
)
Fig.ꢀ4.ꢀXRDꢀpatternsꢀofꢀalcohol‐pretreatedꢀSiO ꢀsupportedꢀcatalystsꢀafterꢀ
reaction.ꢀ
2
Fig.ꢀ3.ꢀXRDꢀpattersꢀofꢀalcohol‐pretreatedꢀSiO ꢀsupportedꢀcatalystsꢀbe‐
foreꢀreaction.ꢀ
2

ꢀ
WentingꢀLuoꢀetꢀal.ꢀ/ꢀChineseꢀJournalꢀofꢀCatalysisꢀ37ꢀ(2016)ꢀ2009–2017ꢀ
2013ꢀ
2
Fig.ꢀ 5.ꢀ HRTEMꢀ imagesꢀ ofꢀ theꢀ spentꢀ alcohol‐pretreatedꢀ SiO ꢀ supportedꢀ catalysts.ꢀ (a)ꢀ Ir‐Re/S;ꢀ (b)ꢀ Ir‐Re/S‐C1;ꢀ (c)ꢀ Ir‐Re/S‐C2;ꢀ (d)ꢀ Ir‐Re/S‐C3;ꢀ (e)ꢀ
Ir‐Re/S‐C4.ꢀ
Fig.ꢀ7ꢀshowsꢀtheꢀNH
3
‐TPDꢀprofilesꢀofꢀtheꢀalcohol‐pretreatedꢀ
takeꢀ amountꢀ thanꢀ theꢀ untreatedꢀ one,ꢀ andꢀ Ir‐Re/S‐C3ꢀ hadꢀ theꢀ
highestꢀuptakeꢀofꢀNH .ꢀTheꢀNH ꢀuptakeꢀindicateꢀtheꢀamountꢀofꢀ
2
SiO ꢀsupportedꢀcatalystsꢀandꢀtheꢀuntreatedꢀone.ꢀAꢀveryꢀweakꢀ
3
3
NH
3
ꢀdesorptionꢀpeakꢀatꢀaꢀwideꢀtemperatureꢀrangeꢀnearꢀ573ꢀKꢀ
superficialꢀReꢀspecies.ꢀSoꢀtheꢀalcohol‐pretreatedꢀcatalystsꢀhaveꢀ
moreꢀsuperficialꢀReꢀspeciesꢀthanꢀIr‐Re/S.ꢀTherefore,ꢀitꢀcanꢀbeꢀ
inferredꢀ fromꢀ theseꢀ resultsꢀ thatꢀ theꢀ Reꢀ speciesꢀ onꢀ theꢀ alco‐
wasꢀdetectedꢀonꢀIr/S.ꢀButꢀRe/Sꢀshowedꢀoneꢀdesorptionꢀpeakꢀatꢀ
90ꢀK.ꢀAllꢀtheꢀcatalystsꢀcontainingꢀReꢀshowedꢀaꢀNH ꢀdesorptionꢀ
atꢀ 490ꢀ K,ꢀ suggestingꢀ thatꢀ theꢀ Reꢀ speciesꢀ wasꢀ theꢀ mainꢀ acidicꢀ
sites.ꢀTableꢀ5ꢀshowsꢀtheꢀNH ꢀuptakeꢀofꢀtheꢀsamplesꢀcalculatedꢀ
byꢀ integrationꢀ ofꢀ theꢀ NH ꢀ desorptionꢀ amount.ꢀ Allꢀ theꢀ alco‐
ꢀ supportedꢀ catalystsꢀ hadꢀ aꢀ largerꢀ NH ꢀ up‐
4
3
2
hol‐pretreatedꢀSiO ꢀsupportedꢀcatalystsꢀwereꢀdispersedꢀbetterꢀ
3
thanꢀonꢀuntreatedꢀone.ꢀBasedꢀonꢀtheꢀresultsꢀthatꢀmostꢀIrꢀatomsꢀ
3
wereꢀcoveredꢀbyꢀReO ꢀandꢀReꢀspeciesꢀparticlesꢀwereꢀsmallerꢀonꢀ
x
hol‐pretreatedꢀ SiO
2
3
Tableꢀ4ꢀ
Desorptionꢀ amountsꢀ ofꢀ H
sorbedꢀamountsꢀofꢀH .ꢀ
2
ꢀ andꢀ dispersionꢀ ofꢀ Irꢀ calculatedꢀ fromꢀ de‐
Tableꢀ3ꢀ
AverageꢀparticleꢀsizeꢀofꢀIrꢀparticlesꢀofꢀdifferentꢀcatalystsꢀmeasuredꢀbyꢀ
TEM.ꢀ
2
Desorptionꢀamountsꢀ ꢀ Dispersionꢀ Irꢀmolesꢀcoveredꢀbyꢀ
Catalystꢀ
catalystꢀ
Ir‐Re/Sꢀ
Ir‐Re/S‐C1ꢀ
Ir‐Re/S‐C2ꢀ
Ir‐Re/S‐C3ꢀ
Ir‐Re/S‐C4ꢀ
AverageꢀparticleꢀsizeꢀofꢀIrꢀspeciesꢀ(nm)ꢀ Dispersionꢀ(%)
2
ofꢀH ꢀ(μmol/g)ꢀ
(%)ꢀ
ꢀ 9.4ꢀ
15.0ꢀ
14.6ꢀ
14.2ꢀ
14.8ꢀ
ReO ꢀ(μmol/g)ꢀ
x
3.0ꢀ
2.5ꢀ
2.5ꢀ
2.4ꢀ
2.9ꢀ
36.8ꢀ
44.2ꢀ
44.2ꢀ
46.0ꢀ
38.1ꢀ
Ir‐Re/Sꢀ
4.9ꢀ
28.5ꢀ
30.4ꢀ
30.8ꢀ
33.1ꢀ
24.2ꢀ
Ir‐Re/S‐C1ꢀ
Ir‐Re/S‐C2ꢀ
Ir‐Re/S‐C3ꢀ
Ir‐Re/S‐C4ꢀ
7.8ꢀ
7.6ꢀ
7.4ꢀ
7.7ꢀ
Re/SiO2
Ir-Re/S-C4
Ir/SiO2
Ir-Re/S-C3
Ir-Re/S-C2
Ir-Re/S
Ir-Re/S-C4
Ir-Re/S-C3
Ir-Re/S-C2
Ir-Re/S-C1
Ir-Re/S-C1
700
Ir-Re/S
400
500
Temperature (K)
‐TPDꢀprofilesꢀofꢀtheꢀalcohol‐pretreatedꢀSiO
600
700
400
500
600
Temperature (K)
Fig.ꢀ6.ꢀH
2
2
ꢀsupportedꢀcata‐
Fig.ꢀ7.ꢀNH
lystsꢀandꢀuntreated.ꢀ
3
2
‐TPDꢀprofilesꢀofꢀtheꢀalcohol‐pretreatedꢀSiO ꢀsupportedꢀcata‐
lysts.ꢀ

2014ꢀ
WentingꢀLuoꢀetꢀal.ꢀ/ꢀChineseꢀJournalꢀofꢀCatalysisꢀ37ꢀ(2016)ꢀ2009–2017ꢀ
Tableꢀ5ꢀ
3
UptakeꢀamountꢀofꢀNH ꢀbyꢀdifferentꢀcatalysts.ꢀ
Catalystꢀ
Ir‐Re/Sꢀ
UptakeꢀofꢀNH ꢀ(µmol/g)ꢀ
3
Ir/SiO2
233.2ꢀ
257.6ꢀ
275.1ꢀ
295.5ꢀ
239.0ꢀ
Ir‐Re/S‐C1ꢀ
Ir‐Re/S‐C2ꢀ
Ir‐Re/S‐C3ꢀ
Ir‐Re/S‐C4ꢀ
ꢀ
Ir-Re/S-C4
Ir-Re/S-C3
Ir-Re/S-C2
Ir-Re/S-C1
Ir-Re/S
theꢀalcohol‐pretreatedꢀSiO
2
ꢀsupportedꢀcatalystsꢀ(especiallyꢀforꢀ
Ir‐Re/S‐C3ꢀcatalyst),ꢀitꢀcanꢀbeꢀconcludedꢀthatꢀthereꢀwereꢀmoreꢀ
Ir‐ReO ꢀ interfacialꢀ sitesꢀ onꢀ theꢀ alcohol‐pretreatedꢀ SiO ꢀ sup‐
portedꢀ catalysts.ꢀ Theꢀ Ir‐ReO ꢀ interfacialꢀ sitesꢀ increasedꢀ whenꢀ
theꢀcarbonꢀnumberꢀofꢀtheꢀpretreatmentꢀalcoholꢀincreasedꢀfromꢀ
Re/SiO2
x
2
2300
2200
2100
2000
1900
1800
1700
x
1
Wavenumber (cm )
1ꢀtoꢀ3,ꢀandꢀthenꢀdecreasedꢀwhenꢀcarbonꢀnumberꢀwasꢀ4.ꢀ
Fig.ꢀ9. InfraredꢀspectraꢀofꢀadsorbedꢀCOꢀonꢀdifferentꢀcatalysts.ꢀ
Inꢀorderꢀtoꢀinvestigateꢀtheꢀacidꢀtypesꢀofꢀtheꢀcatalysts,ꢀFT‐IRꢀ
analysisꢀofꢀ pyridineꢀ adsorptionꢀwasꢀ carriedꢀout.ꢀAsꢀ shownꢀinꢀ
3
.3.ꢀ ꢀ Catalyticꢀactivityꢀ
–1
Fig.ꢀ 8,ꢀ theꢀ bandsꢀ atꢀ 1540ꢀ cm ꢀ wereꢀ attributedꢀ toꢀ Brönstedꢀ
–1
acidicꢀsitesꢀandꢀtheꢀbandsꢀatꢀ1450ꢀcm ꢀwereꢀassignedꢀtoꢀLewisꢀ
Theꢀ catalyticꢀ performanceꢀ ofꢀ theꢀ alcohol‐pretreatedꢀ SiO ꢀ
2
–1
acidicꢀsitesꢀ[35].ꢀTheꢀabsorptionꢀbandsꢀatꢀ1490ꢀcm ꢀwereꢀdueꢀ
toꢀpyridineꢀadsorptionꢀonꢀbothꢀBrönstedꢀacidicꢀandꢀLewisꢀacid‐
icꢀ sitesꢀ [36].ꢀ Generally,ꢀ theꢀ spectraꢀ obtainedꢀ whenꢀ pyridineꢀ
desorbedꢀ atꢀ 423,ꢀ 623ꢀ andꢀ 723ꢀ Kꢀ correspondedꢀ toꢀ allꢀ acidic,ꢀ
medium‐strongꢀacidicꢀandꢀstrongꢀacidicꢀsites,ꢀrespectively.ꢀThisꢀ
revealedꢀthatꢀtheꢀLewisꢀacidicꢀsitesꢀonꢀtheꢀcatalystsꢀwereꢀweakꢀ
acidsꢀ andꢀtheꢀBrönstedꢀ acidicꢀsitesꢀ containedꢀ weakꢀacidsꢀ andꢀ
medium‐strongꢀacids.ꢀThereꢀwereꢀnoꢀstrongꢀacidicꢀsitesꢀonꢀtheꢀ
Ir‐Re/SꢀandꢀIr‐Re/S‐C3ꢀcatalysts.ꢀTheꢀB/Lꢀacidicꢀsitesꢀratioꢀofꢀ
theꢀIr‐Re/SꢀandꢀIr‐Re/S‐C3ꢀcatalystsꢀwereꢀbothꢀapproximatelyꢀ
supportedꢀcatalystsꢀisꢀlistedꢀinꢀTableꢀ6.ꢀAꢀmaximumꢀconversionꢀ
ofꢀ 59.5%ꢀ wasꢀ achievedꢀ whenꢀ theꢀ glycerolꢀ feedꢀ withꢀ theꢀ con‐
centrationꢀofꢀ80%ꢀreactedꢀoverꢀIr‐Re/S‐C3ꢀatꢀ403ꢀKꢀandꢀ8ꢀMPa.ꢀ
Theꢀconversionꢀincreasedꢀwithꢀanꢀincreaseꢀinꢀcarbonꢀnumbersꢀ
fromꢀ1ꢀtoꢀ3.ꢀHowever,ꢀthereꢀwasꢀaꢀdecreaseꢀinꢀtheꢀconversionꢀofꢀ
glycerolꢀwhenꢀtheꢀcarbonꢀnumbersꢀofꢀtheꢀalcoholꢀwasꢀincreasedꢀ
toꢀ4.ꢀWithꢀtheꢀincreaseꢀofꢀglycerolꢀconversion,ꢀtheꢀselectivityꢀtoꢀ
1
1
,3‐propanediolꢀ andꢀ 1,2‐propanediolꢀ decreasedꢀ andꢀ thatꢀ toꢀ
‐propanol,ꢀ2‐propanolꢀandꢀpropaneꢀincreased.ꢀThisꢀsuggestedꢀ
thatꢀtheꢀhighꢀconversionꢀofꢀglycerolꢀwasꢀaccompaniedꢀbyꢀtheꢀ
consecutiveꢀ reactionꢀ ofꢀ 1,3‐propanediolꢀ andꢀ 1,2‐propanediol,ꢀ
thusꢀ leadingꢀ toꢀ theꢀ lowerꢀ selectivityꢀ toꢀ theseꢀ andꢀ theꢀ higherꢀ
selectivityꢀtoꢀexcessiveꢀdecompositionꢀbyproduct.ꢀHowever,ꢀtheꢀ
ratioꢀofꢀremovalꢀselectivityꢀtoꢀsecondaryꢀhydroxylꢀgroups/halfꢀ
ofꢀprimaryꢀhydroxylꢀgroupsꢀ(S2‐OH/(S1‐OH/2))ꢀofꢀallꢀofꢀtheꢀcata‐
3.3.ꢀ
Re/SꢀcatalystꢀdidꢀnotꢀadsorbꢀCO,ꢀasꢀshownꢀinꢀFig.ꢀ9.ꢀThere‐
fore,ꢀtheꢀlocalꢀenvironmentꢀofꢀtheꢀIrꢀsitesꢀcanꢀbeꢀprobedꢀbyꢀCOꢀ
adsorptionꢀusingꢀFT‐IR.ꢀAdsorptionꢀofꢀCOꢀonꢀIr/Sꢀcatalystꢀre‐
–1
sultedꢀ inꢀ aꢀ mainꢀ bandꢀ atꢀ 2084ꢀ cm .ꢀ Theꢀ adsorptionꢀ bandsꢀ
shiftedꢀ toꢀ lowerꢀ wavenumbersꢀ onꢀ theꢀ Ir‐Reꢀ systemꢀ catalysts,ꢀ
whichꢀdemonstratedꢀthatꢀthereꢀwereꢀsmallerꢀIrꢀparticlesꢀinꢀtheꢀ
Ir‐ReꢀsystemꢀcatalystsꢀandꢀtheꢀReꢀspeciesꢀpromotedꢀtheꢀdisper‐
sionꢀofꢀIrꢀspeciesꢀ[37].ꢀ
lystsꢀvariedꢀlittle,ꢀwhichꢀmeansꢀthatꢀtheꢀpretreatedꢀSiO ꢀsupportꢀ
2
hasꢀlittleꢀinfluenceꢀonꢀS2‐OH/(S1‐OH/2).ꢀAllꢀtheꢀcatalystsꢀmayꢀhaveꢀ
theꢀ sameꢀ kindꢀ ofꢀ activeꢀ sites.ꢀ Theꢀ smallꢀ decreaseꢀ ofꢀ
S2‐OH/(S1‐OH/2)ꢀforꢀtheꢀIr‐Re/S‐C3ꢀcatalystꢀmayꢀbeꢀcausedꢀbyꢀtheꢀ
competitiveꢀ adsorptionꢀ ofꢀ aꢀ higherꢀ concentrationꢀ ofꢀ primaryꢀ
hydroxylꢀgroups.ꢀAꢀhigherꢀremovalꢀyieldꢀofꢀsecondaryꢀhydroxylꢀ
groupꢀ(Y2‐OH)ꢀwasꢀobservedꢀonꢀtheꢀIr‐Re/S‐C3ꢀcatalystꢀ(28.3%).ꢀ
1540
1490
1450
Y
2‐OHꢀofꢀallꢀtheꢀalcohol‐pretreatedꢀSiO ꢀsupportedꢀcatalystsꢀwasꢀ
2
7
23 K
23 K
23 K
higherꢀthanꢀthatꢀofꢀtheꢀIr‐Re/Sꢀcatalyst.ꢀWhenꢀtheꢀweightꢀhourlyꢀ
6
spaceꢀ velocityꢀ (WHSV)ꢀ wasꢀ increasedꢀ toꢀ 0.76ꢀ h ,ꢀ theꢀ perfor‐
–1
4
manceꢀofꢀtheꢀIr‐Re/S‐C3ꢀcatalystꢀisꢀalsoꢀlistedꢀinꢀTableꢀ6.ꢀTheꢀ
conversionꢀdecreasedꢀtoꢀ43.4%ꢀwhichꢀwasꢀsimilarꢀtoꢀIr‐Re/S.ꢀ
Accordinglyꢀ theꢀ selectivityꢀ toꢀ 1,3‐propanediolꢀ andꢀ
1,2‐propanediolꢀincreasedꢀtoꢀ39.4%ꢀandꢀ12.6%,ꢀwhichꢀwasꢀalsoꢀ
similarꢀtoꢀthatꢀofꢀIr‐Re/S.ꢀThisꢀcoincidesꢀwithꢀtheꢀinferenceꢀweꢀ
Ir-Re/S
7
23 K
6
23 K
4
23 K
proposedꢀthatꢀtheꢀalcohol‐pretreatedꢀSiO ꢀsupportedꢀcatalystsꢀ
2
Ir-Re/S-C3
didꢀnotꢀpromoteꢀtheꢀremovalꢀselectivityꢀtoꢀsecondaryꢀhydroxylꢀ
groups.ꢀ ꢀ
Weꢀ alsoꢀ conductedꢀ aꢀexperimentꢀonꢀtheꢀhydrogenolysisꢀofꢀ
1,3‐propanediolꢀ overꢀ Ir‐Re/Sꢀ andꢀ Ir‐Re/S‐C3.ꢀ Theꢀ resultsꢀ areꢀ
shownꢀ inꢀ Tableꢀ 7.ꢀ Theꢀ conversionꢀ ofꢀ 1,3‐propanediolꢀ onꢀ
Ir‐Re/S‐C3ꢀ wasꢀ muchꢀ higherꢀ thanꢀ thatꢀ onꢀ Ir‐Re/S.ꢀ Inꢀ conclu‐
1
550
1500
1450
1400
1350
1
Wavenumber (cm )
Fig.ꢀ 8. FT‐IRꢀ spectroscopyꢀ ofꢀ pyridineꢀ adsorptionꢀ onꢀ Ir‐Re/Sꢀ andꢀ
Ir‐Re/S‐C3ꢀcatalysts.ꢀ

ꢀ
WentingꢀLuoꢀetꢀal.ꢀ/ꢀChineseꢀJournalꢀofꢀCatalysisꢀ37ꢀ(2016)ꢀ2009–2017ꢀ
2015ꢀ
Tableꢀ6ꢀ
[a]
Catalyticꢀperformanceꢀofꢀtheꢀalcohol‐pretreatedꢀSiO ꢀsupportedꢀcatalysts .ꢀ
2
Conversionꢀ ꢀ
Catalystꢀ
Selectivityꢀ(%)
ꢀ
2‐OH/(S1‐OH/2)ꢀhꢀ
Y
2‐OHꢀ
iꢀ
S
(%)ꢀ
1,3‐PDꢀbꢀ
1,2‐PDꢀcꢀ
1‐POꢀdꢀ
2‐POꢀeꢀ
3
C H
8ꢀ
Othersꢀ ꢀ
f
Ir‐Re/Sꢀ
42.7ꢀ
53.6ꢀ
56.8ꢀ
59.5ꢀ
44.5ꢀ
43.8ꢀ
39.1ꢀ
35.9ꢀ
32.9ꢀ
29.4ꢀ
40.6ꢀ
38.8ꢀ
12.4ꢀ
11.6ꢀ
11.2ꢀ
ꢀ 9.1ꢀ
15.8ꢀ
33.8ꢀ
37.0ꢀ
39.5ꢀ
43.1ꢀ
26.1ꢀ
33.9ꢀ
10.6ꢀ
10.2ꢀ
10.6ꢀ
10.6ꢀ
ꢀ 7.5ꢀ
ꢀ 9.4ꢀ
4.0ꢀ
5.0ꢀ
5.4ꢀ
7.4ꢀ
9.4ꢀ
5.1ꢀ
0.1ꢀ
0.3ꢀ
0.2ꢀ
0.4ꢀ
0.6ꢀ
0.4ꢀ
2.0ꢀ
2.0ꢀ
1.9ꢀ
1.8ꢀ
2.0ꢀ
2.1ꢀ
21.6ꢀ
26.6ꢀ
27.5ꢀ
28.3ꢀ
22.3ꢀ
22.2ꢀ
Ir‐Re/S‐C1ꢀ
Ir‐Re/S‐C2ꢀ
Ir‐Re/S‐C3ꢀ
Ir‐Re/S‐C4ꢀ
Ir‐Re/S‐C3 ꢀ
[g]
12.4ꢀ
aꢀ
–1
Reactionꢀcondition:ꢀpꢀ=ꢀ8.0ꢀMPa,ꢀTꢀ=ꢀ403ꢀK,ꢀWHSVꢀ=ꢀ0.53ꢀh ,ꢀ1.5ꢀgꢀcatalyst,ꢀ80ꢀwt%ꢀglycerolꢀaqueousꢀsolution,VH2ꢀ=ꢀ40ꢀmL/min,ꢀTOSꢀ=ꢀ36ꢀh.ꢀReductionꢀ
bꢀ
cꢀ
dꢀ
eꢀ
conditions:ꢀpꢀ=ꢀ0.1ꢀMPa,ꢀVH2ꢀ=ꢀ40ꢀmL/min,ꢀTꢀ=ꢀ443ꢀK,ꢀtꢀ=ꢀ2ꢀh.ꢀ 1,3‐PDꢀ=ꢀ1,3‐propandiol.ꢀ 1,2‐PDꢀ=ꢀ1,2‐propanediol.ꢀ 1‐POꢀ=ꢀ1‐propanol.ꢀ 2‐POꢀ=ꢀ
2
solution,ꢀVH2ꢀ=ꢀ40ꢀml/min,ꢀtꢀ=ꢀ36ꢀh.ꢀ Ratioꢀofꢀremovalꢀselectivityꢀtoꢀsecondaryꢀhydroxylꢀgroupsꢀandꢀhalfꢀofꢀprimaryꢀhydroxylꢀgroups.ꢀ Removalꢀyieldꢀofꢀ
fꢀ
gꢀ
–1
‐propanol.ꢀ Othersꢀincludeꢀethanolꢀandꢀethane.ꢀ Reactionꢀconditions:ꢀpꢀ=ꢀ8.0ꢀMPa,ꢀT=ꢀ403ꢀK,ꢀWHSV=ꢀ0.76ꢀh ,ꢀ1.5ꢀgꢀcatalyst,ꢀ80ꢀwt%ꢀglycerolꢀaqueousꢀ
hꢀ
iꢀ
secondaryꢀhydroxylꢀgroup.ꢀ
ꢀ
sion,ꢀ theꢀ conversionꢀ ofꢀ glycerolꢀ overꢀ theꢀ alcohol‐pretreatedꢀ
SiO ꢀ supportedꢀ catalystsꢀ wasꢀ increased,ꢀ butꢀ thereꢀ wasꢀ littleꢀ
effectꢀ onꢀ theꢀ removalꢀ ofꢀ secondaryꢀ hydroxylꢀ groups.ꢀ Theꢀ re‐
verseꢀtrendꢀofꢀtheꢀconversionꢀofꢀglycerolꢀandꢀtheꢀselectivityꢀtoꢀ
carbonꢀnumberꢀincreasedꢀtoꢀ4,ꢀtheꢀamountꢀofꢀC4ꢀalcoholꢀmole‐
culesꢀwasꢀsmaller,ꢀsoꢀtheꢀdispersionꢀofꢀIrꢀspeciesꢀandꢀReꢀspeciesꢀ
decreased.ꢀ Accordingly,ꢀ theꢀ conversionꢀ overꢀ Ir‐Re/S‐C4ꢀ de‐
creased.ꢀ
2
1
,3‐propanediolꢀwasꢀcausedꢀbyꢀtheꢀconsecutiveꢀreactionꢀofꢀourꢀ
targetꢀproductꢀ1,3‐propanediol.ꢀ
FromꢀtheꢀTEM,ꢀH ‐TPDꢀandꢀNH
thereꢀ wereꢀ moreꢀ Ir‐ReO ꢀ interfacialꢀ sitesꢀ onꢀ theꢀ alco‐
hol‐pretreatedꢀ SiO ꢀ supportedꢀ catalysts.ꢀ Theꢀ interfacialꢀ sitesꢀ
wereꢀcorrelatedꢀwithꢀtheꢀconversionꢀofꢀglycerol.ꢀThisꢀsupportedꢀ
theꢀ suggestionꢀ thatꢀ theꢀ Ir‐ReO ꢀinterfacialꢀsitesꢀareꢀtheꢀactiveꢀ
sitesꢀforꢀglycerolꢀhydrogenolysis.ꢀ
TheꢀXRDꢀandꢀTEMꢀmeasurementsꢀofꢀtheꢀspentꢀcatalystsꢀre‐
vealedꢀ thatꢀ theꢀ Irꢀ particlesꢀ ofꢀ Ir‐Re/S‐Cnꢀ wereꢀ smallerꢀ thanꢀ
Ir‐Re/S,ꢀ whileꢀ theꢀ smallestꢀ particlesꢀ wasꢀ achievedꢀ onꢀ
Ir‐Re/S‐C3.ꢀThisꢀwasꢀaꢀresultꢀfromꢀthatꢀtheꢀinteractionꢀofꢀmetalꢀ
speciesꢀwithꢀisolatedꢀSi–OHꢀpromotedꢀtheꢀformationꢀofꢀsmallerꢀ
supportedꢀmetalꢀparticlesꢀ[23,26,27].ꢀIsolatedꢀSi–OHꢀwouldꢀbeꢀ
formedꢀbyꢀtheꢀsegregationꢀofꢀsurfaceꢀalkoxylꢀgroupsꢀ[22,32,38].ꢀ
Therefore,ꢀitꢀwasꢀconsideredꢀthatꢀtheꢀpretreatmentꢀofꢀsupportsꢀ
withꢀalcoholsꢀincreasedꢀisolatedꢀSi–OHꢀonꢀtheꢀsupportꢀsurface,ꢀ
4.ꢀ ꢀ Conclusionsꢀ
2
3
‐TPDꢀresults,ꢀweꢀknowꢀthatꢀ
x
Aꢀsimpleꢀmethodꢀforꢀpreparingꢀhighlyꢀdispersedꢀsupportedꢀ
metalꢀ catalystꢀ forꢀ glycerolꢀ hydrogenolysisꢀ wasꢀ developedꢀ byꢀ
theꢀmodificationꢀofꢀ aꢀ supportꢀ surfaceꢀusingꢀC1–C4ꢀnormalꢀal‐
cohols.ꢀForꢀtheꢀcatalystsꢀpreparedꢀusingꢀtheꢀalcohol‐pretreatedꢀ
2
x
SiO
Theꢀhigherꢀconversionꢀ wasꢀ dueꢀtoꢀmoreꢀinterfacialꢀ sitesꢀofꢀIrꢀ
andꢀ ReO ꢀ onꢀ theꢀ alcohol‐pretreatedꢀ SiO ꢀ supportedꢀ catalysts.ꢀ
2
ꢀ supports,ꢀ aꢀ higherꢀ conversionꢀ ofꢀ glycerolꢀ wasꢀ achieved.ꢀ
x
2
Theꢀkindꢀofꢀactiveꢀsitesꢀonꢀallꢀtheꢀcatalystsꢀwasꢀsimilarꢀbecauseꢀ
theyꢀ gaveꢀ almostꢀ theꢀ sameꢀ removalꢀ selectivityꢀ toꢀ secondaryꢀ
alkoxylꢀ groups.ꢀ Aꢀ higherꢀ conversionꢀ wasꢀ accompaniedꢀ byꢀ aꢀ
lowerꢀselectivityꢀtoꢀ1,3‐propanediol,ꢀwhichꢀwasꢀcausedꢀbyꢀcon‐
secutiveꢀ hydrogenolysis.ꢀ However,ꢀ theꢀ removalꢀ yieldꢀ ofꢀ sec‐
ondaryꢀalkoxylꢀgroupsꢀonꢀtheꢀalcohol‐pretreatedꢀSiO ꢀsupport‐
2
edꢀcatalysts,ꢀespeciallyꢀIr‐Re/S‐C3,ꢀwasꢀhigherꢀthanꢀthatꢀonꢀtheꢀ
untreatedꢀ catalyst.ꢀ Therefore,ꢀ byꢀ selectingꢀ anꢀ organicꢀ solventꢀ
withꢀaꢀsuitableꢀchainꢀlengthꢀtoꢀmodifyꢀtheꢀcatalystꢀsupport,ꢀtheꢀ
supportedꢀmetalꢀorꢀmetalꢀoxideꢀwasꢀadjustedꢀorꢀcontrolledꢀtoꢀ
formꢀaꢀdesignedꢀparticleꢀsizeꢀandꢀhadꢀdesignedꢀsurfaceꢀproper‐
ties.ꢀ Thisꢀ isꢀ highlyꢀ attractiveꢀ forꢀ optimizingꢀ theꢀ catalyticꢀ per‐
formanceꢀofꢀdesignedꢀcatalysts.ꢀ
resultingꢀinꢀtheꢀformationꢀofꢀsmallerꢀIrO
ꢀparticles.ꢀItꢀwasꢀalsoꢀ
2
reportedꢀthatꢀtheꢀstrongꢀinteractionꢀbetweenꢀmetalꢀspeciesꢀandꢀ
supportꢀ alsoꢀ improvedꢀ theꢀ dispersionꢀ ofꢀ metalꢀ particlesꢀ
[
24,25].ꢀ Aꢀ strongꢀ interactionꢀ betweenꢀ IrO
whichꢀwasꢀconcludedꢀfromꢀtheꢀTPRꢀresults.ꢀThisꢀwouldꢀalsoꢀbeꢀ
aꢀ reasonꢀ forꢀ theꢀ formationꢀ ofꢀ smallerꢀ IrO ꢀ particles.ꢀ Longerꢀ
2
ꢀ andꢀ SiO ꢀ existed,ꢀ
2
2
carbonꢀchainsꢀofꢀalkoxylꢀhaveꢀaꢀbetterꢀseparationꢀeffectꢀtoꢀhin‐
derꢀtheꢀmetalꢀprecursorsꢀfromꢀaggregation,ꢀsoꢀtheꢀdispersionꢀofꢀ
IrꢀspeciesꢀandꢀReꢀspeciesꢀincreasedꢀwhenꢀtheꢀcarbonꢀnumberꢀofꢀ
theꢀpretreatmentꢀalcoholꢀincreasedꢀfromꢀ1ꢀtoꢀ3.ꢀButꢀwhenꢀtheꢀ
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[
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2