Glycerol hydrogenolysis to n-propanol over Zr-Al composite oxide-supported Pt catalysts

Article abstract of DOI:10.1016/S1872-2067(18)63068-2

Zr-Al mixed oxide supported Pt catalysts with different Zr/Al mole ratios (2.5%Pt/Zr_xAl_1–xO_y) were synthesized by an impregnation method and used for the selective hydrogenolysis of glycerol to n-propanol in an autoclave reactor. The catalysts were fully characterized by X-ray powder diffraction, Brunauer-Emmett-Teller surface area analysis, CO chemisorption, H₂ temperature- programmed reduction, pyridine-infrared spectroscopy, and NH₃-temperature-programmed desorption. The results revealed that the Zr/Al ratio on the support significantly affected the size of the platinum particles and the properties of the acid sites on the catalysts. The catalytic performance was well correlated with the acidic properties of the catalyst; specifically, more acid sites contributed to the conversion and strong acid sites with a specific intensity contributed to the deep dehydration of glycerol to form n-propanol. Among the tested catalysts, 2.5 wt% Pt/Zr_0.7Al_0.3O_y exhibited excellent selectivity for n-propanol with 81.2% glycerol conversion at 240 °C and 6.0 MPa H₂ pressure when 10% aqueous glycerol solution was used as the substrate. In addition, the effect of various reaction parameters, such as H₂ content, reaction temperature, reaction time, and number of experimental cycles were studied to determine the optimized reaction conditions and to evaluate the stability of the catalyst.

Full text of DOI:10.1016/S1872-2067(18)63068-2

ChineseꢀJournalꢀofꢀCatalysisꢀ39ꢀ(2018)ꢀ1121–1128
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ꢀ ꢀ ꢀ
ꢀ ꢀ ꢀ ꢀ
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
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ꢀ
Article
Glycerolꢀhydrogenolysisꢀtoꢀn‐propanolꢀoverꢀZr‐Alꢀcompositeꢀ ꢀ
oxide‐supportedꢀPtꢀcatalystsꢀ
a
a
a
b
a,
ChuangꢀLiꢀ ,ꢀBoꢀHeꢀ ,ꢀYuꢀLingꢀ ,ꢀChi‐WingꢀTsangꢀ ,ꢀChanghaiꢀLiangꢀ *
ꢀ
aꢀLaboratoryꢀofꢀAdvancedꢀMaterialsꢀandꢀCatalyticꢀEngineering,ꢀDalianꢀUniversityꢀofꢀTechnology,ꢀDalianꢀ116024,ꢀLiaoning,ꢀChinaꢀ
bꢀFacultyꢀofꢀScienceꢀandꢀTechnology,ꢀTechnologicalꢀandꢀHigherꢀEducationꢀInstituteꢀofꢀHongꢀKong,ꢀHongꢀKongꢀ50011,ꢀChinaꢀ
A R T I C L E ꢀ I N F O ꢀ
A B S T R A C T ꢀ
Articleꢀhistory:ꢀ
Zr‐AlꢀmixedꢀoxideꢀsupportedꢀPtꢀcatalystsꢀwithꢀdifferentꢀZr/Alꢀmoleꢀratiosꢀ(2.5%Pt/Zr
x
Al1–x
O )ꢀwereꢀ
y
Receivedꢀ29ꢀJanuaryꢀ2018ꢀ
Acceptedꢀ22ꢀMarchꢀ2018ꢀ
Publishedꢀ5ꢀJuneꢀ2018ꢀ
synthesizedꢀbyꢀanꢀimpregnationꢀmethodꢀandꢀusedꢀforꢀtheꢀselectiveꢀhydrogenolysisꢀofꢀglycerolꢀtoꢀ
n‐propanolꢀinꢀanꢀautoclaveꢀreactor.ꢀTheꢀcatalystsꢀwereꢀfullyꢀcharacterizedꢀbyꢀX‐rayꢀpowderꢀdiffrac‐
tion,ꢀ Brunauer‐Emmett‐Tellerꢀ surfaceꢀ areaꢀ analysis,ꢀ COꢀ chemisorption,ꢀ H
2
ꢀ temperature‐pro‐
ꢀ
grammedꢀ reduction,ꢀ pyridine‐infraredꢀ spectroscopy,ꢀ andꢀ NH ‐temperature‐programmedꢀ desorp‐
3
tion.ꢀTheꢀresultsꢀrevealedꢀthatꢀtheꢀZr/Alꢀratioꢀonꢀtheꢀsupportꢀsignificantlyꢀaffectedꢀtheꢀsizeꢀofꢀtheꢀ
platinumꢀparticlesꢀandꢀtheꢀpropertiesꢀofꢀtheꢀacidꢀsitesꢀonꢀtheꢀcatalysts.ꢀTheꢀcatalyticꢀperformanceꢀ
wasꢀwellꢀcorrelatedꢀwithꢀtheꢀacidicꢀpropertiesꢀofꢀtheꢀcatalyst;ꢀspecifically,ꢀmoreꢀacidꢀsitesꢀcontrib‐
utedꢀtoꢀtheꢀconversionꢀandꢀstrongꢀacidꢀsitesꢀwithꢀaꢀspecificꢀintensityꢀcontributedꢀtoꢀtheꢀdeepꢀdehy‐
Keywords:ꢀ
Glycerolꢀhydrogenolysisꢀ
n‐Propanolꢀ
Pt‐basedꢀcatalystꢀ
Zr‐Alꢀcompositeꢀoxideꢀ
Zr/Alꢀratio
drationꢀofꢀglycerolꢀtoꢀformꢀn‐propanol.ꢀAmongꢀtheꢀtestedꢀcatalysts,ꢀ2.5ꢀwt%ꢀPt/Zr0.7Al0.3
excellentꢀselectivityꢀforꢀn‐propanolꢀwithꢀ81.2%ꢀglycerolꢀconversionꢀatꢀ240ꢀ°Cꢀandꢀ6.0ꢀMPaꢀH
sureꢀwhenꢀ10%ꢀaqueousꢀglycerolꢀsolutionꢀwasꢀusedꢀasꢀtheꢀsubstrate.ꢀInꢀaddition,ꢀtheꢀeffectꢀofꢀvari‐
ousꢀreactionꢀparameters,ꢀsuchꢀasꢀH ꢀcontent,ꢀreactionꢀtemperature,ꢀreactionꢀtime,ꢀandꢀnumberꢀofꢀ
y
O ꢀexhibitedꢀ
2
ꢀpres‐
2
experimentalꢀcyclesꢀwereꢀstudiedꢀtoꢀdetermineꢀtheꢀoptimizedꢀreactionꢀconditionsꢀandꢀtoꢀevaluateꢀ
theꢀstabilityꢀofꢀtheꢀcatalyst.ꢀ
©ꢀ2018,ꢀDalianꢀInstituteꢀofꢀChemicalꢀPhysics,ꢀChineseꢀAcademyꢀofꢀSciences.
PublishedꢀbyꢀElsevierꢀB.V.ꢀAllꢀrightsꢀreserved.
1
.ꢀ ꢀ Introductionꢀ
directꢀconversionꢀofꢀglycerolꢀtoꢀn‐POꢀremainsꢀessentiallyꢀunex‐
plored.ꢀFewꢀresearchersꢀhaveꢀstudiedꢀtheꢀdirectꢀconversionꢀofꢀ
glycerolꢀtoꢀn‐propanol,ꢀdespiteꢀtheꢀfactꢀthatꢀn‐propanolꢀisꢀrela‐
Inꢀrecentꢀyears,ꢀtheꢀvastꢀamountsꢀofꢀglycerolꢀgeneratedꢀbyꢀ
biodieselꢀrefineriesꢀmotivatedꢀresearchꢀonꢀtheꢀdevelopmentꢀofꢀ
newꢀwaysꢀtoꢀtransformꢀglycerolꢀintoꢀhighꢀvalue‐addedꢀchemi‐
calsꢀ[1].ꢀCatalyticꢀhydrogenolysisꢀisꢀoneꢀofꢀtheꢀmostꢀattractiveꢀ
waysꢀinꢀthisꢀcontextꢀ[2,3].ꢀUpꢀtoꢀnow,ꢀresearchꢀonꢀtheꢀhydro‐
genolysisꢀofꢀglycerolꢀwasꢀmainlyꢀfocusedꢀonꢀitsꢀconversionꢀtoꢀ
diolsꢀ suchꢀ asꢀ 1,2‐propandiolꢀ (1,2‐PD)ꢀ orꢀ 1,3‐propandiolꢀ
tivelyꢀ expensiveꢀ (price:ꢀ 1,3‐propandiolꢀ >ꢀ n‐propanolꢀ >ꢀ 1,2‐
ꢀ
propandiolꢀ >ꢀ ethyleneꢀ glycolꢀ [10]).ꢀ Further,ꢀ n‐propanolꢀ isꢀ aꢀ
valuableꢀchemicalꢀwidelyꢀusedꢀasꢀaꢀsolvent,ꢀorganicꢀintermedi‐
ate,ꢀ andꢀ rawꢀ materialꢀ [11,12].ꢀ Inꢀ additionꢀ toꢀ theꢀ one‐potꢀ hy‐
drodeoxygenationꢀ ofꢀ glycerolꢀ toꢀ propyleneꢀ inꢀ aꢀ batchꢀ reactorꢀ
[13,14],ꢀsingle‐stepꢀ[15]ꢀandꢀtandemꢀprocessesꢀ[16,17]ꢀofꢀglyc‐
(1,3‐PD)ꢀ[4–9].ꢀn‐Propanolꢀ(n‐PO)ꢀisꢀanotherꢀvaluableꢀchemicalꢀ
2
erolꢀtoꢀolefinsꢀ(GTO)ꢀinꢀH ꢀhaveꢀbeenꢀdevelopedꢀbyꢀfirstꢀcon‐
producedꢀduringꢀtheꢀhydrogenolysisꢀofꢀglycerol;ꢀhowever,ꢀtheꢀ
vertingꢀtheꢀdehydrationꢀproductsꢀ(mainlyꢀacroleinꢀandꢀacetol)ꢀ
*ꢀCorrespondingꢀauthor.ꢀTel/Fax:ꢀ+86‐411‐84986353;ꢀE‐mail:ꢀchanghai@dlut.edu.cnꢀ
ThisꢀworkꢀwasꢀsupportedꢀbyꢀtheꢀNationalꢀNaturalꢀScienceꢀFoundationꢀofꢀChinaꢀ(21573031,ꢀ21373038),ꢀtheꢀProgramꢀforꢀExcellentꢀTalentsꢀinꢀDalianꢀ
Cityꢀ(2016RD09),ꢀandꢀtheꢀDoctoralꢀScientificꢀResearchꢀFoundationꢀofꢀLiaoꢀNingꢀProvinceꢀ(20170520395).ꢀ ꢀ
DOI:ꢀ10.1016/S1872‐2067(18)63068‐2ꢀ|ꢀhttp://www.sciencedirect.com/science/journal/18722067ꢀ|ꢀChin.ꢀJ.ꢀCatal.,ꢀVol.ꢀ39,ꢀNo.ꢀ6,ꢀJuneꢀ2018ꢀ ꢀ ꢀ

1122ꢀ
ChuangꢀLiꢀetꢀal.ꢀ/ꢀChineseꢀJournalꢀofꢀCatalysisꢀ39ꢀ(2018)ꢀ1121–1128ꢀ
toꢀpropanolsꢀandꢀthenꢀtoꢀpropylene.ꢀ
cedure.ꢀ
Atꢀ present,ꢀ researchꢀ onꢀ glycerolꢀ hydrogenolysisꢀ toꢀ
n‐propanolꢀisꢀmainlyꢀfocusedꢀonꢀimprovingꢀtheꢀacidityꢀofꢀcata‐
lystsꢀ toꢀ promoteꢀ theirꢀ dehydrationꢀ ability.ꢀ Zhuꢀ etꢀ al.ꢀ [12]ꢀ re‐
portedꢀaꢀone‐stepꢀhydrogenolysisꢀofꢀbiomass‐derivedꢀglycerolꢀ
Zr‐Alꢀ compositeꢀ oxide‐supportedꢀ platinumꢀ catalystsꢀ wereꢀ
preparedꢀbyꢀaꢀwetꢀimpregnationꢀmethod.ꢀAnꢀaqueousꢀsolutionꢀ
ofꢀ H
2
PtCl
6
·6H Oꢀ wasꢀ impregnatedꢀ withꢀ requiredꢀ amountsꢀ ofꢀ
2
differentꢀ Zr‐Alꢀ compositeꢀ oxidesꢀ individuallyꢀ underꢀ vigorousꢀ
stirringꢀ forꢀ 24ꢀ h.ꢀ Afterꢀ rotaryꢀ evaporation,ꢀ theꢀ impregnatedꢀ
samplesꢀwereꢀallowedꢀtoꢀdryꢀovernightꢀatꢀ110ꢀ°Cꢀandꢀtheꢀre‐
sultingꢀ materialsꢀ wereꢀ calcinedꢀ atꢀ 350ꢀ °Cꢀ forꢀ 4ꢀ h.ꢀ Platinumꢀ
loadingꢀinꢀallꢀtheꢀcatalystsꢀwasꢀfixedꢀatꢀ2.5ꢀwt%ꢀandꢀtheꢀcata‐
toꢀ propanolꢀ overꢀ differentꢀ supportedꢀ Pt‐H SiW12O40ꢀ (HSiW)ꢀ
4
bi‐functionalꢀ catalystsꢀ inꢀ aqueousꢀ media.ꢀ Itꢀ wasꢀ believedꢀ thatꢀ
theꢀbalanceꢀbetweenꢀtheꢀactiveꢀsitesꢀandꢀacidꢀsitesꢀisꢀimportantꢀ
forꢀ glycerolꢀ conversion.ꢀ Later,ꢀ Samudralꢀ etꢀ al.ꢀ [18]ꢀ comparedꢀ
2
differentꢀ heteropolyacidsꢀ inꢀ theꢀ Pt‐HPA/ZrO ꢀ catalystꢀ seriesꢀ
lystsꢀ wereꢀ denotedꢀ asꢀ 2.5%Pt/ZrO
2
,ꢀ 2.5%Pt/Zr0.3Al0.7
O ,ꢀ
y
andꢀfoundꢀthatꢀPt‐H ꢀexhibitedꢀtheꢀhighestꢀpro‐
4
SiW12
O
40/ZrO
2
2.5%Pt/Zr0.5Al0.5
O
y
,ꢀ2.5%Pt/Zr0.7Al0.3 ,ꢀandꢀ2.5%Pt/Al
O
y
2 3
O .ꢀ
panolꢀ (n‐propanolꢀ andꢀ i‐propanol)ꢀ yield.ꢀ Itsꢀ highꢀ activityꢀ wasꢀ
attributedꢀtoꢀtheꢀgreaterꢀdispersionꢀofꢀPtꢀparticlesꢀandꢀstrongerꢀ
acidityꢀofꢀtheꢀsupport.ꢀGuoꢀetꢀal.ꢀ[19]ꢀfoundꢀthatꢀmesoporousꢀ
niobiumꢀ tungstenꢀ oxide‐supportedꢀ platinumꢀ exhibitedꢀ goodꢀ
propaneꢀselectivity,ꢀbutꢀtheꢀcomplexꢀ synthesisꢀ processꢀofꢀtheꢀ
catalystꢀhampersꢀitsꢀindustrialꢀapplication.ꢀInꢀaddition,ꢀitꢀwasꢀ
foundꢀthatꢀchangesꢀinꢀtheꢀacidityꢀofꢀtheꢀcatalystꢀcouldꢀsignifi‐
2.2.ꢀ ꢀ Catalyticꢀreactionꢀtestsꢀ
TheꢀhydrogenolysisꢀreactionꢀwasꢀcarriedꢀoutꢀinꢀaꢀHastelloyꢀ
Alloyꢀautoclave.ꢀPriorꢀtoꢀtheꢀreaction,ꢀtheꢀcatalystꢀwasꢀreducedꢀ
byꢀ 25%ꢀ H
mL/min)ꢀatꢀ350ꢀ°Cꢀforꢀ4ꢀh.ꢀForꢀeachꢀreaction,ꢀtheꢀstandardꢀex‐
perimentalꢀconditionsꢀwereꢀasꢀfollows:ꢀinitialꢀH ꢀpressureꢀofꢀ6ꢀ
2
ꢀ inꢀ anꢀ Arꢀ atmosphereꢀ (flowingꢀ atꢀ aꢀ rateꢀ ofꢀ 60ꢀ
cantlyꢀ affectꢀ productꢀ distributionꢀ whenꢀ 10Ni‐30H
4
SiW/Al
2
O
3
ꢀ
2
+
wasꢀusedꢀinꢀtheꢀreaction,ꢀinꢀwhichꢀCs ꢀcanꢀbeꢀexchangedꢀtoꢀalterꢀ
theꢀ acidityꢀ ofꢀ theꢀ catalystꢀ [10].ꢀ Inꢀ spiteꢀ ofꢀ previousꢀ researchꢀ
efforts,ꢀtheꢀspecificꢀrelationshipꢀbetweenꢀhydrogenolysisꢀprod‐
uctꢀdistributionꢀandꢀacidityꢀofꢀtheꢀcatalystꢀisꢀstillꢀnotꢀclearꢀandꢀ
needsꢀtoꢀbeꢀevaluated.ꢀ
MPa,ꢀtemperatureꢀofꢀ230ꢀ°C,ꢀstirringꢀspeedꢀofꢀ800ꢀr/min,ꢀandꢀ
reactionꢀtimeꢀofꢀ8ꢀh.ꢀInꢀaꢀtypicalꢀreaction,ꢀ30ꢀgꢀofꢀaꢀ10%ꢀglycerolꢀ
solutionꢀandꢀ0.3ꢀgꢀofꢀtheꢀcatalystꢀwereꢀloadedꢀintoꢀtheꢀreactor,ꢀ
afterꢀwhichꢀtheꢀautoclaveꢀwasꢀsealedꢀandꢀflushedꢀthriceꢀwithꢀH ꢀ
2
toꢀremoveꢀtheꢀairꢀinꢀtheꢀreactor.ꢀAfterꢀtheꢀreactionꢀtemperatureꢀ
reachedꢀtheꢀdesignatedꢀvalue,ꢀtheꢀreactionꢀbegan.ꢀAtꢀtheꢀendꢀofꢀ
theꢀ reaction,ꢀ theꢀ liquidꢀ productsꢀ wereꢀ analyzedꢀ usingꢀ aꢀ gasꢀ
chromatographꢀ(7890FꢀGC)ꢀequippedꢀwithꢀaꢀcapillaryꢀcolumnꢀ
(FFAP:ꢀ30ꢀmꢀ×ꢀ0.32ꢀmmꢀ×ꢀ0.5ꢀμm)ꢀandꢀaꢀflameꢀionizationꢀde‐
tector.ꢀn‐Butanolꢀwasꢀusedꢀasꢀtheꢀinternalꢀstandard.ꢀ
Combinedꢀ ZrO ꢀ isꢀ oftenꢀ usedꢀ asꢀ aꢀ carrierꢀ duringꢀ glycerolꢀ
2
hydrogenolysisꢀtoꢀpropanolꢀowingꢀtoꢀtheꢀfactꢀthatꢀtheꢀcompo‐
siteꢀ metalꢀ oxideꢀ hasꢀ strongerꢀ acidity,ꢀ higherꢀ specificꢀ surfaceꢀ
area,ꢀ andꢀ betterꢀ stabilityꢀ thanꢀ aꢀ single‐componentꢀ oxideꢀ
[20–23].ꢀ Inꢀ thisꢀ study,ꢀ Zr‐Alꢀ compositeꢀ oxidesꢀ withꢀ differentꢀ
ratiosꢀwereꢀsynthesizedꢀandꢀanꢀimpregnationꢀmethodꢀwasꢀem‐
ployedꢀ toꢀ useꢀ themꢀ asꢀ supportsꢀ forꢀ platinumꢀ catalysts.ꢀ Theseꢀ
catalystsꢀwereꢀthenꢀappliedꢀduringꢀglycerolꢀhydrogenolysisꢀtoꢀ
exploreꢀ theꢀ effectꢀ ofꢀ theꢀ supportsꢀ onꢀ theꢀ transformationꢀ ofꢀ
2.3.ꢀ ꢀ Characterizationꢀ
Powderꢀ X‐rayꢀ diffractionꢀ (XRD)ꢀ dataꢀ wereꢀ recordedꢀ onꢀ aꢀ
glycerolꢀtoꢀn‐propanol.ꢀTheꢀeffectsꢀofꢀH
2
ꢀcontent,ꢀreactionꢀtem‐
ShimadzuꢀXRD‐7000SꢀdiffractometerꢀwithꢀaꢀCuꢀK ꢀmonochro‐
α
perature,ꢀreactionꢀtime,ꢀandꢀcatalystꢀstabilityꢀwereꢀalsoꢀexam‐
ined.ꢀ
matizedꢀradiationꢀsourceꢀ(λꢀ=ꢀ1.5418ꢀÅ),ꢀwhichꢀisꢀoperatedꢀatꢀ
40ꢀkVꢀandꢀ30ꢀmA.ꢀTheꢀdiffractionꢀdataꢀwereꢀcollectedꢀinꢀaꢀcon‐
tinuousꢀ scanningꢀ modeꢀ atꢀ aꢀ scanꢀ speedꢀ ofꢀ 3°/minꢀ inꢀ theꢀ 2θꢀ
rangeꢀofꢀ5°ꢀtoꢀ90°.ꢀ ꢀ
2.ꢀ ꢀ ꢀ Experimentalꢀ
N
2
ꢀ adsorption‐desorptionꢀ isothermsꢀ wereꢀ generatedꢀ onꢀ aꢀ
Quantachromeꢀ Autosorb‐iQ‐Cꢀ instrument.ꢀ Beforeꢀ theꢀ N ꢀ phy‐
sisorptionꢀmeasurements,ꢀallꢀtheꢀsamplesꢀ(approximatelyꢀ0.1ꢀg)ꢀ
wereꢀheatedꢀtoꢀ300ꢀ°Cꢀinꢀvacuumꢀ(10 ꢀTorr)ꢀforꢀ3ꢀhꢀtoꢀremoveꢀ
anyꢀadsorbedꢀimpurities.ꢀLater,ꢀtheꢀexperimentꢀwasꢀperformedꢀ
atꢀ‒196ꢀ°C.ꢀ
2
.1.ꢀ ꢀ PreparationꢀofꢀZr‐Alꢀmixedꢀoxide‐supportedꢀPtꢀcatalystsꢀ
2
–3
Zr‐Alꢀ compositeꢀ oxidesꢀ withꢀ differentꢀ Zr/Alꢀ ratiosꢀ wereꢀ
preparedꢀbyꢀtheꢀco‐precipitationꢀmethod.ꢀInꢀaꢀgeneralꢀprocess,ꢀ
ZrOCl ·8H Oꢀ andꢀ Al(NO ·9H Oꢀ withꢀ differentꢀ moleꢀ ratiosꢀ
2
2
)
3 3
2
wereꢀdissolvedꢀinꢀdeionizedꢀwaterꢀ(120ꢀmL)ꢀatꢀroomꢀtempera‐
ture.ꢀToꢀtheꢀresultingꢀtransparentꢀsolution,ꢀaqueousꢀammoniaꢀ
TheꢀquantitiesꢀofꢀmetalꢀactiveꢀsitesꢀwereꢀestimatedꢀfromꢀCOꢀ
adsorptionꢀ analysisꢀperformedꢀ usingꢀaꢀ MicrometerꢀAutochemꢀ
2910ꢀinstrumentꢀatꢀroomꢀtemperature.ꢀInꢀaꢀtypicalꢀprocess,ꢀtheꢀ
(25%–28%)ꢀwasꢀdropwiseꢀaddedꢀunderꢀvigorousꢀstirringꢀuntilꢀ
theꢀ solutionꢀ becameꢀ aꢀ gel‐likeꢀ solid.ꢀ Theꢀ whiteꢀ gelꢀ solidꢀ wasꢀ
agedꢀatꢀroomꢀtemperatureꢀforꢀ12ꢀh,ꢀfiltered,ꢀandꢀwashedꢀwithꢀ
deionizedꢀ waterꢀ untilꢀ noꢀ chlorideꢀ ionsꢀ couldꢀ beꢀ detectedꢀ
catalystꢀwasꢀreducedꢀinꢀflowingꢀH ꢀ(30ꢀmL/min)ꢀatꢀ350ꢀ°Cꢀforꢀ2ꢀ
2
h,ꢀfollowedꢀbyꢀpurgingꢀwithꢀflowingꢀHeꢀforꢀ2ꢀh.ꢀSubsequently,ꢀ
COꢀwasꢀpulsedꢀuntilꢀtheꢀpeakꢀareaꢀdidꢀnotꢀchangeꢀanymoreꢀatꢀ
roomꢀtemperature.ꢀ ꢀ
againstꢀanꢀAgNO ꢀsolution.ꢀTheꢀresultingꢀprecipitateꢀwasꢀdriedꢀ
3
atꢀ110ꢀ°Cꢀforꢀ12ꢀhꢀandꢀthenꢀcalcinedꢀatꢀ400ꢀ°Cꢀforꢀ4ꢀh.ꢀSimilarly,ꢀ
Zr‐Alꢀ compositeꢀ oxidesꢀ withꢀ differentꢀ metalꢀ ratiosꢀ wereꢀ pre‐
Forꢀtheꢀtemperature‐programmedꢀreductionꢀofꢀH
theꢀcatalystsꢀ(50ꢀmg)ꢀwereꢀsubjectedꢀtoꢀaꢀflowꢀofꢀ10%ꢀ(volumeꢀ
fraction)ꢀH /Arꢀ(totalꢀflowꢀrateꢀofꢀ30ꢀmL/min)ꢀforꢀ1ꢀhꢀtoꢀstabi‐
2
ꢀ(H ‐TPR),ꢀ
2
x y
paredꢀandꢀdenotedꢀasꢀZr Al1–xO ꢀ(xꢀandꢀ1–xꢀrepresentꢀtheꢀmoleꢀ
2
ratiosꢀofꢀZrꢀandꢀAlꢀrespectively,ꢀxꢀ=ꢀ0.3,ꢀ0.5,ꢀandꢀ0.7;ꢀyꢀstandsꢀforꢀ
theꢀuncertainꢀvalueꢀofꢀoxygenꢀelement).ꢀForꢀcomparison,ꢀsingleꢀ
lizeꢀtheꢀthermalꢀconductivityꢀdetectorꢀ(TCD)ꢀsignal.ꢀAfterꢀthat,ꢀ
theꢀtemperatureꢀwasꢀincreasedꢀfromꢀ30ꢀtoꢀ450ꢀ°Cꢀatꢀaꢀrateꢀofꢀ10ꢀ
°C/min.ꢀTheꢀtemperature‐dependentꢀchangesꢀinꢀtheꢀconcentra‐
oxideꢀAl
2
O
3
ꢀandꢀZrO ꢀwereꢀalsoꢀsynthesizedꢀbyꢀtheꢀsameꢀpro‐
2

ꢀ
ChuangꢀLiꢀetꢀal.ꢀ/ꢀChineseꢀJournalꢀofꢀCatalysisꢀ39ꢀ(2018)ꢀ1121–1128ꢀ
1123ꢀ
tionꢀofꢀH ꢀwereꢀrecordedꢀonꢀanꢀon‐lineꢀTCD.ꢀ
2
Tableꢀ1ꢀ
Poreꢀstructureꢀcharacteristicsꢀandꢀdispersionꢀofꢀtheꢀmetalꢀactiveꢀsitesꢀofꢀ
Theꢀ acidityꢀ ofꢀ theꢀ reducedꢀ catalystꢀ wasꢀ measuredꢀ byꢀ theꢀ
NH ‐temperature‐programmedꢀ desorptionꢀ (NH ‐TPD)ꢀ tech‐
nique.ꢀ Priorꢀ toꢀ NH ꢀ adsorption,ꢀ theꢀ sampleꢀ wasꢀ outgassedꢀ atꢀ
00ꢀ°Cꢀforꢀ1ꢀhꢀinꢀorderꢀtoꢀremoveꢀtheꢀimpuritiesꢀonꢀtheꢀcatalystꢀ
surface.ꢀAfterꢀcoolingꢀdownꢀtoꢀ50ꢀ°CꢀinꢀaꢀHeꢀflow,ꢀNH ꢀadsorp‐
tionꢀ wasꢀ carriedꢀ outꢀ (30ꢀ mL/min)ꢀ forꢀ 40ꢀ min.ꢀ Physisorbedꢀ
ammoniaꢀwasꢀeliminatedꢀbyꢀflowingꢀHeꢀforꢀ1ꢀh.ꢀNH ‐TPDꢀwasꢀ
performedꢀinꢀHeꢀflowꢀatꢀaꢀtemperatureꢀrampꢀofꢀ10ꢀ°C/minꢀfromꢀ
0ꢀtoꢀ800ꢀ°CꢀonꢀaꢀQuantachromeꢀInstrumentsꢀChembetꢀ3000ꢀ
system.ꢀ
3
3
2.5%Pt/Zr
x
Al1–x
O ꢀcatalystsꢀwithꢀdifferentꢀZr/Alꢀratios.ꢀ
y
3
BETꢀaꢀ
2
pꢀaꢀ
3
pꢀaꢀ
Disꢀbꢀ
(%)ꢀ
dꢀbꢀ
(nm)ꢀ
S
V
d
P
Catalystꢀ
2
(m /g) (cm /g)ꢀ (nm)ꢀ
3
2.5%Pt/ZrO
2
ꢀ
ꢀ 65ꢀ
ꢀ 67ꢀ
ꢀ 87ꢀ
120ꢀ
265ꢀ
0.067ꢀ
0.087ꢀ
0.081ꢀ
0.090ꢀ
0.110ꢀ
25.7ꢀ
ꢀ 4.3ꢀ
ꢀ 3.7ꢀ
10.2ꢀ
ꢀ 8.9ꢀ
30.3ꢀ
19.0ꢀ
23.6ꢀ
30.1ꢀ
34.8ꢀ
3.9ꢀ
6.2ꢀ
5.0ꢀ
3.9ꢀ
3.4ꢀ
2.5%Pt/Zr
2.5%Pt/Zr
2.5%Pt/Zr
0
0
0
.
7
Al
Al
Al
0
.
3 y
O ꢀ
5 y
O ꢀ
7 y
O ꢀ
3
.
5
0
.
.
3
0
.
2
2.5%Pt/Al O ꢀ
3
5
aꢀ
MeasuredꢀbyꢀN
CalculatedꢀbyꢀCOꢀchemisorption.ꢀ
2
ꢀadsorption‐desorptionꢀisotherms.ꢀ ꢀ
bꢀ
ꢀ
3
.ꢀ ꢀ Resultsꢀandꢀdiscussionꢀ
.1.ꢀ ꢀ Characterizationꢀofꢀ2.5%Pt/Zr
Fig.ꢀ 1.ꢀ showsꢀ theꢀ XRDꢀ patternsꢀ ofꢀ 2.5%Pt/Zr
2
theꢀAlꢀcontent.ꢀAsꢀforꢀ2.5%Pt/ZrO ,ꢀtheꢀlargestꢀporeꢀsizeꢀ(25.7ꢀ
3
x
Al1–x
O
y
ꢀcatalystsꢀ
nm)ꢀcouldꢀbeꢀattributedꢀtoꢀtheꢀaccumulationꢀofꢀsphericalꢀZrO ꢀ
2
particles.ꢀ Theꢀ dispersionꢀ ofꢀ Ptꢀ particlesꢀ rangedꢀ widelyꢀ fromꢀ
19.0%ꢀtoꢀ34.8%,ꢀwhileꢀtheꢀparticleꢀsizeꢀrangedꢀfromꢀ3.4ꢀtoꢀ6.2ꢀ
x
Al1–x
y
O ꢀ cata‐
lystsꢀreducedꢀatꢀ350ꢀ°C.ꢀFirst,ꢀdiffractionꢀpeaksꢀcorrespondingꢀ
toꢀ theꢀ Ptꢀ metalꢀ particlesꢀ wereꢀ onlyꢀ detectedꢀ inꢀ theꢀ caseꢀ ofꢀ
nm.ꢀ Theꢀ catalysts,ꢀ 2.5%Pt/Zr0.7Al0.3
O
y
ꢀandꢀ2.5%Pt/Zr0.5Al0.5O ,ꢀ
y
exhibitedꢀ largerꢀ Ptꢀ particles,ꢀ 6.2ꢀ andꢀ 5.0ꢀ nm,ꢀ respectively,ꢀ
whichꢀ isꢀ consistentꢀ withꢀ theꢀ XRDꢀ results.ꢀ Theꢀ activeꢀ sitesꢀ ofꢀ
largerꢀPtꢀparticlesꢀmayꢀaffectꢀtheꢀselectivityꢀofꢀn‐propanol.ꢀ
Theꢀ Zr‐Alꢀ compositeꢀ oxide‐supportedꢀ Ptꢀ catalystsꢀ wereꢀ
2
.5%Pt/Zr0.7Al0.3
O
y
ꢀ andꢀ 2.5%Pt/Zr0.5Al0.5
onꢀtheꢀintensitiesꢀofꢀtheꢀXRDꢀpeaks,ꢀtheꢀsizeꢀofꢀtheꢀPtꢀparticlesꢀ
inꢀ theꢀ 2.5%Pt/Zr0.7Al0.3 ꢀ catalystꢀ wasꢀ largeꢀ comparedꢀ toꢀ
.5%Pt/Zr0.5Al0.5 ;ꢀ further,ꢀ theꢀ Ptꢀ particlesꢀ wereꢀ wellꢀ dis‐
persedꢀonꢀtheꢀotherꢀthreeꢀcatalystsꢀ[24].ꢀTheꢀdiffractionꢀpeaksꢀ
ofꢀ 2.5%Pt/ZrO ꢀ andꢀ 2.5%Pt/Al ꢀ wereꢀ attributedꢀ toꢀ ortho‐
rhombicꢀZrO ꢀ(JCPDSꢀNo.ꢀ34‐1084)ꢀandꢀhexagonalꢀAl ꢀ(JCPDSꢀ
O
y
.ꢀ Moreover,ꢀ basedꢀ
O
y
2
O
y
studiedꢀbyꢀH ‐TPRꢀasꢀshownꢀinꢀFig.ꢀ2.ꢀItꢀwasꢀreportedꢀthatꢀtheꢀ
2
activeꢀsitesꢀhighlyꢀdispersedꢀonꢀcatalystꢀsurfacesꢀhaveꢀaꢀstrongꢀ
interactionꢀwithꢀtheꢀsupportꢀandꢀthatꢀtheꢀreductionꢀtempera‐
turesꢀ underꢀ suchꢀ conditionsꢀ wouldꢀ beꢀ higherꢀ [27,28].ꢀ There‐
fore,ꢀitꢀcouldꢀbeꢀdeducedꢀfromꢀtheꢀreductionꢀtemperaturesꢀofꢀ
2
O
2 3
2
O
2 3
No.ꢀ 13‐0373),ꢀ respectively.ꢀ However,ꢀ theꢀ catalystsꢀ exhibitedꢀ
lowꢀcrystallinities,ꢀwhichꢀcouldꢀbeꢀattributedꢀtoꢀtheꢀlowꢀcalcina‐
tionꢀtemperatures.ꢀInꢀtheꢀcaseꢀofꢀZr‐Alꢀoxide‐supportedꢀPtꢀcat‐
2.5%Pt/Al
thatꢀ2.5%Pt/Al
theꢀ caseꢀ ofꢀ 2.5%Pt/Zr0.5Al0.5
2
O
3
,ꢀ 2.5%Pt/Zr0.3Al0.7
ꢀexhibitedꢀaꢀhigherꢀmetalꢀdispersion.ꢀWhileꢀinꢀ
ꢀ andꢀ 2.5%Pt/Zr0.7Al0.3 ꢀ cata‐
O
y
,ꢀ andꢀ 2.5%Pt/ZrO
2
ꢀ catalystsꢀ
O
2 3
alysts,ꢀ2.5%Pt/Zr
wereꢀalmostꢀsimilar,ꢀwithꢀtheꢀemergenceꢀofꢀaꢀbroadꢀpeakꢀnearꢀ
2°;ꢀhowever,ꢀtheꢀpositionsꢀofꢀtheꢀPtꢀparticleꢀpeaksꢀwereꢀdif‐
x y
Al1–xO ꢀ(xꢀ=ꢀ0.3,ꢀ0.5,ꢀandꢀ0.7),ꢀtheꢀXRDꢀpeaksꢀ
O
y
O
y
lysts,ꢀtheyꢀdisplayedꢀtwoꢀreductionꢀpeaks,ꢀoneꢀnearꢀ125ꢀ°Cꢀandꢀ
theꢀ otherꢀ nearꢀ 325ꢀ °C.ꢀ Thisꢀ indicatesꢀ thatꢀ theꢀ catalystsꢀ con‐
tainedꢀactiveꢀingredientsꢀofꢀtwoꢀdifferentꢀsizes.ꢀTheꢀlowerꢀtem‐
peratureꢀreductionꢀpeakꢀwasꢀattributedꢀtoꢀtheꢀbiggerꢀparticlesꢀ
thatꢀ interactedꢀ weaklyꢀ withꢀ theꢀ supportꢀ [29].ꢀ Theꢀ reductionꢀ
peakꢀatꢀ325ꢀ°CꢀcouldꢀbeꢀascribedꢀtoꢀsmallerꢀPtꢀoxides,ꢀwhichꢀ
3
ferent.ꢀ Thereꢀ wereꢀ noꢀ peaksꢀ correspondingꢀ toꢀ singleꢀ phaseꢀ
zirconiaꢀorꢀalumina,ꢀwhichꢀindicatedꢀthatꢀtheꢀaluminaꢀandꢀzir‐
coniaꢀ componentsꢀ wereꢀ combinedꢀ uniformlyꢀ toꢀ formꢀ compo‐
siteꢀmetalꢀoxidesꢀ[25].ꢀ
Theꢀ specificꢀ surfaceꢀ areasꢀ andꢀ dispersionsꢀ ofꢀ metalꢀ activeꢀ
sitesꢀ areꢀ shownꢀ inꢀ Tableꢀ 1.ꢀ Itꢀ isꢀ toꢀ beꢀ notedꢀ thatꢀ theꢀ specificꢀ
surfaceꢀareasꢀandꢀporeꢀvolumesꢀincreasedꢀwithꢀanꢀincreaseꢀinꢀ
wereꢀhighlyꢀdispersedꢀonꢀtheꢀsupport.ꢀTheꢀH ‐TPRꢀresultsꢀwereꢀ
consistentꢀwithꢀtheꢀresultsꢀofꢀXRDꢀandꢀCOꢀchemisorptionꢀanal‐
yses.ꢀ ꢀ
2
2.5%Pt/ZrO2
2.5%Pt/ZrO2
Pt(111)
Pt(200)
2.5%Pt/Zr0.7Al0.3Oy
2.5%Pt/Zr0.7Al0.3Oy
Pt(220)
Pt(311)
2
.5%Pt/Zr0.5Al0.5Oy
2
.5%Pt/Zr0.5Al0.5Oy
.5%Pt/Zr0.3Al0.7Oy
2
2.5%Pt/Zr0.3Al0.7Oy
2.5%Pt/Al2O3
2.5%Pt/Al2O3
1
0
20
30
40
50
)
60
70
80
90
50
100
150
200
Temperature ( C)
‐TPRꢀ profilesꢀ ofꢀ 2.5%Pt/Zr Al1–x
250
300
350
400
450
o
o
2
 (
Fig.ꢀ1.ꢀXRDꢀpatternsꢀofꢀ2.5%Pt/Zr
x
Al1–ꢀx
O
y
ꢀcatalystsꢀwithꢀdifferentꢀZr‐Alꢀ
Fig.ꢀ 2.ꢀ H
Zr/Alꢀratios.ꢀ
2
x
y
O ꢀ catalystsꢀ withꢀ differentꢀ
ratios.ꢀ

1124ꢀ
ChuangꢀLiꢀetꢀal.ꢀ/ꢀChineseꢀJournalꢀofꢀCatalysisꢀ39ꢀ(2018)ꢀ1121–1128ꢀ
Toꢀfurtherꢀelucidateꢀtheꢀtypesꢀofꢀacidsꢀonꢀtheꢀcatalystsꢀandꢀ
theꢀ ratioꢀ ofꢀ strongꢀ Brönstedꢀ toꢀ Lewisꢀ acidꢀ sites,ꢀ pyridineꢀ ad‐
sorptionꢀanalysisꢀwasꢀcarriedꢀoutꢀandꢀtheꢀcollectedꢀspectraꢀareꢀ
presentedꢀ inꢀ Fig.ꢀ 3.ꢀ Theꢀ resultsꢀ clearlyꢀ showedꢀ thatꢀ theꢀ acidꢀ
sitesꢀ wereꢀ mainlyꢀ Lewisꢀ acidsꢀ onꢀ theꢀ 2.5%Pt/Zr
x
Al1–x
O ꢀ cata‐
y
–1
lysts.ꢀ Briefly,ꢀ theꢀ intenseꢀ peakꢀ atꢀ 1450ꢀ cm ꢀ wasꢀ assignedꢀ toꢀ
pyridineꢀadsorptionꢀonꢀLewisꢀacidꢀsites.ꢀAnotherꢀcomparativelyꢀ
–1
lesserꢀbandꢀatꢀ1541ꢀcm ,ꢀdueꢀtoꢀtheꢀN‐Hꢀbendingꢀofꢀpyridiniumꢀ
ions,ꢀ isꢀ theꢀ characteristicꢀ adsorptionꢀ peakꢀ ofꢀ pyridineꢀ onꢀ
2.5%Pt/Zr7Al3
–1
Brönstedꢀ acidꢀ sites.ꢀ Theꢀ peakꢀ locatedꢀ atꢀ 1490ꢀ cm ꢀ wasꢀ at‐
tributedꢀtoꢀtheꢀcombinationꢀadsorptionꢀofꢀ pyridineꢀmoleculesꢀ
onꢀbothꢀBrönstedꢀandꢀLewisꢀacidꢀsitesꢀ[30].ꢀToꢀinvestigateꢀtheꢀ
effectꢀofꢀdifferentꢀZr/Alꢀmoleꢀratiosꢀonꢀtheꢀsurfaceꢀacidityꢀofꢀtheꢀ
2.5%Pt/Zr5Al
5
as‐synthesizedꢀ 2.5%Pt/Zr
riedꢀ outꢀ andꢀ theꢀ resultsꢀ areꢀ shownꢀ inꢀ Fig.ꢀ 4.ꢀ Inꢀ pureꢀ ox‐
ide‐supportedꢀ catalysts,ꢀ suchꢀ asꢀ 2.5%Pt/ZrO andꢀ
.5%Pt/Al ,ꢀtheꢀacidꢀdistributionꢀwasꢀuniform.ꢀWeak,ꢀmedi‐
x
Al1–x
O
y
ꢀ catalysts,ꢀ NH
3
‐TPDꢀ wasꢀ car‐
2.5%Pt/Zr3Al7
2
ꢀ
2.5%Pt/Al2O3
2
O
2 3
umꢀstrength,ꢀandꢀstrongꢀacidꢀsitesꢀexistedꢀonꢀtheꢀsurfacesꢀofꢀtheꢀ
catalysts.ꢀWhenꢀusingꢀZr‐Alꢀcompositeꢀoxidesꢀasꢀtheꢀsupports,ꢀ
2.5%Pt/ZrO
2
suchꢀasꢀinꢀtheꢀcaseꢀofꢀ2.5%Pt/Zr0.3Al0.7
O
y
,ꢀNH ꢀdesorptionꢀpeaksꢀ
3
locatedꢀatꢀlowerꢀtemperaturesꢀdecreasedꢀandꢀtheꢀacidꢀdistribu‐
tionsꢀ transferredꢀ toꢀ strongerꢀ acidꢀ sites.ꢀ Suchꢀ changesꢀ inꢀ thisꢀ
trendꢀwereꢀconfirmedꢀwithꢀincreasingꢀZr/Alꢀmoleꢀratios.ꢀThereꢀ
1
00
200
300
400
500
600
700
800
o
Temperature ( C)
3
Fig.ꢀ4.ꢀNH ‐TPDꢀprofilesꢀofꢀZr‐Alꢀcompositeꢀoxide‐supportedꢀplatinumꢀ
areꢀnoꢀweakꢀacidꢀsitesꢀonꢀtheꢀ2.5%Pt/Zr0.5Al0.5
theꢀ caseꢀ ofꢀ 2.5%Pt/Zr0.7Al0.3 ,ꢀ theꢀ percentageꢀ ofꢀ strongꢀ acidꢀ
exhibitedꢀaꢀmaximumꢀvalueꢀofꢀ91.2%.ꢀInꢀaddition,ꢀtheꢀdesorp‐
tionꢀ peakꢀ ofꢀ theꢀ 2.5%Pt/Zr0.7Al0.3 ꢀ catalystꢀ becameꢀ muchꢀ
O ꢀcatalystꢀandꢀinꢀ
y
catalystsꢀwithꢀdifferentꢀZr/Alꢀratios.ꢀ
O
y
3
.2.ꢀ ꢀ Hydrogenolysisꢀofꢀglycerolꢀoverꢀsupportedꢀcatalystsꢀ
O
y
sharperꢀ andꢀ intensified,ꢀ whichꢀ indicatedꢀ thatꢀ theꢀ strongꢀ acidꢀ
sitesꢀwereꢀmoreꢀinꢀnumberꢀ[25].ꢀTheyꢀwouldꢀcontributeꢀtoꢀanꢀ
improvementꢀinꢀtheꢀproductꢀselectivityꢀ[10].ꢀ ꢀ
Forꢀeaseꢀofꢀanalysis,ꢀtheꢀacidꢀsitesꢀwereꢀclassifiedꢀasꢀweakꢀ
acid,ꢀmediumꢀ strongꢀ acid,ꢀandꢀstrongꢀacidꢀ sitesꢀwhenꢀ theꢀde‐
sorptionꢀtemperaturesꢀwereꢀ<200,ꢀ200–450,ꢀandꢀ>450ꢀ°C,ꢀre‐
spectively.ꢀ Theꢀ distributionsꢀ ofꢀ acidꢀ sitesꢀ andꢀ percentagesꢀ ofꢀ
Theꢀsynthesizedꢀcatalystsꢀwereꢀusedꢀforꢀtheꢀhydrogenolysisꢀ
ofꢀglycerolꢀandꢀtheꢀeffectꢀofꢀdifferentꢀZr/Alꢀratiosꢀonꢀtheꢀreac‐
tionꢀwasꢀinvestigated.ꢀTheꢀresultsꢀareꢀshownꢀinꢀTableꢀ3.ꢀBasedꢀ
onꢀ availableꢀ literatureꢀ [32]ꢀ andꢀ ourꢀ experimentalꢀ results,ꢀ aꢀ
possibleꢀreactionꢀrouteꢀforꢀglycerolꢀhydrogenolysisꢀisꢀproposed.ꢀ
Acid‐catalyzedꢀ dehydrationꢀ ofꢀ glycerolꢀ initiallyꢀ proceedsꢀ toꢀ
formꢀ acetolꢀ orꢀ 3‐hydroxypropionaldehyde,ꢀ whichꢀ canꢀ subse‐
quentlyꢀhydrogenateꢀtoꢀ1,2‐PDꢀandꢀ1,3‐PDꢀoverꢀmetalꢀcatalysts,ꢀ
respectively.ꢀ Asꢀ shownꢀ inꢀ Tableꢀ 3,ꢀ aꢀ higherꢀ selectivityꢀ forꢀ
theꢀsingleꢀpeakꢀatꢀtheꢀNH ꢀ desorptionꢀtemperatureꢀofꢀ580ꢀ°Cꢀ
3
wereꢀcalculatedꢀbyꢀpeakꢀfittingꢀ(Tableꢀ2).ꢀInꢀaddition,ꢀitꢀisꢀworthꢀ
notingꢀ thatꢀ theꢀ totalꢀ numberꢀ ofꢀ acidꢀ sitesꢀ increasedꢀ withꢀ anꢀ
increaseꢀ inꢀ theꢀ Alꢀ content,ꢀ whichꢀ wouldꢀ beꢀ beneficialꢀ forꢀ theꢀ
conversionꢀofꢀglycerol.ꢀ
1
,3‐PDꢀ thanꢀ 1,2‐PDꢀ onꢀ Pt/ZrO
meanwhile,ꢀ higherꢀ selectivityꢀ canꢀ beꢀ foundꢀ forꢀ 1,2‐PDꢀ onꢀ
,ꢀandꢀPt/Al .ꢀThisꢀseemsꢀtoꢀindi‐
cateꢀ thatꢀn‐POꢀisꢀformedꢀmainlyꢀbyꢀfurtherꢀhydrogenolysisꢀofꢀ
,3‐PDꢀ overꢀ Pt/ZrO .ꢀ Formationꢀ ofꢀ 1,3‐PDꢀ
2 y
ꢀ andꢀ Pt/Zr0.7Al0.3O ꢀ isꢀ obvious;ꢀ
Pt/Zr0.5Al0.5
O
y
,ꢀPt/Zr0.3Al0.7
O
y
O
2 3
1
2
ꢀ andꢀ Pt/Zr0.7Al0.3
O
y
2.5%Pt/Al2O3
1541
viaꢀglycerolꢀhydrogenolysisꢀrequiresꢀtheꢀselectiveꢀcleavageꢀofꢀaꢀ
secondaryꢀhydroxyꢀgroupꢀamongꢀtheꢀthreeꢀhydroxyꢀgroupsꢀofꢀaꢀ
1490
(B)
(L+B)
Tableꢀ2ꢀ
1450
Acidꢀsiteꢀdistributionꢀonꢀ2.5%Pt/Zr
x
Al1–x
O ꢀcatalysts.ꢀ
y
2
.5%Pt/Zr0.3Al0.7Oy
.5%Pt/Zr0.7Al0.3Oy
(L)
Acidꢀstrengthꢀdistributionꢀ(%)ꢀ
a
T
n ꢀ ꢀ
Catalystꢀ
Singleꢀpeakꢀ
b
Wꢀa
Mꢀaꢀ
Sꢀ ꢀ
a
(mmol/gꢀ)
(580ꢀ°C)ꢀ
2
2
2
2
.5%Pt/ZrO
2
ꢀ
16.3 17.0ꢀ 66.7ꢀ
ꢀ 0.0 8.8ꢀ 91.2ꢀ
ꢀ 0.0 12.8ꢀ 87.2ꢀ
37.8 ꢀ 8.4ꢀ 53.7ꢀ
45.0 ꢀ 9.5ꢀ 45.5ꢀ
54.2ꢀ
91.2ꢀ
52.5ꢀ
37.8ꢀ
1.77ꢀ
2.87ꢀ
3.58ꢀ
4.78ꢀ
6.27ꢀ
.5%Pt/Zr
.5%Pt/Zr
0
0
0
.
7
Al
Al
Al
0
.
3 y
O ꢀ
5 y
O ꢀ
7 y
O ꢀ
.
5
0
.
1400 1420 1440 1460 1480 1500 1520 1540 1560
2.5%Pt/Zr
2.5%Pt/Al O ꢀ
.
3
0
.
1
20.2ꢀ
2
3
Wavenumber (cm )
Fig.ꢀ3.ꢀ FT‐IRꢀ spectraꢀ ofꢀ adsorbedꢀ pyridineꢀ onꢀ 2.5%Pt/Zr
lystsꢀwithꢀdifferentꢀZr/Alꢀratiosꢀ(desorptionꢀatꢀ300ꢀ°C).ꢀ
aꢀW,ꢀM,ꢀS,ꢀandꢀn
ꢀstandꢀforꢀtheꢀnumberꢀofꢀweak,ꢀmedium,ꢀstrong,ꢀandꢀ
T
x
Al1–x
O ꢀcata‐
y
b
totalꢀacidꢀsites,ꢀrespectively.ꢀ ꢀTheꢀpercentageꢀofꢀacidꢀsites,ꢀwhoseꢀNH
desorptionꢀtemperatureꢀisꢀ580ꢀ°C.ꢀ
3

ꢀ
ChuangꢀLiꢀetꢀal.ꢀ/ꢀChineseꢀJournalꢀofꢀCatalysisꢀ39ꢀ(2018)ꢀ1121–1128ꢀ
1125ꢀ
Tableꢀ3ꢀ
HydrogenolysisꢀofꢀglycerolꢀoverꢀZr‐Alꢀcompositeꢀoxide‐supportedꢀPtꢀcatalysts.ꢀ
Selectivityꢀ(%)ꢀ
Entryꢀ
Catalystꢀ
Conv.ꢀ(%)ꢀ
n‐POꢀ
75.4ꢀ
82.7ꢀ
53.9ꢀ
41.9ꢀ
36.3ꢀ
1,2‐PDꢀ
ꢀ 3.1ꢀ
ꢀ 4.3ꢀ
ꢀ 2.8ꢀ
45.3ꢀ
48.4ꢀ
i‐POꢀ
14.6ꢀ
ꢀ 4.7ꢀ
36.7ꢀ
ꢀ 3.9ꢀ
ꢀ 6.4ꢀ
1,3‐PDꢀ
EGꢀ
1.3ꢀ
0.8ꢀ
1.3ꢀ
4.5ꢀ
3.7ꢀ
MAꢀ
0.3ꢀ
0.2ꢀ
1.6ꢀ
1.3ꢀ
0.3ꢀ
EAꢀ
0.2ꢀ
0.5ꢀ
1.4ꢀ
‒ꢀ
0.8ꢀ
Othersꢀ
1
ꢀ
2.5%Pt/ZrO
2
ꢀ
26.4ꢀ
34.2ꢀ
38.0ꢀ
38.4ꢀ
38.9ꢀ
4.9ꢀ
6.4ꢀ
1.3ꢀ
2.9ꢀ
3.4ꢀ
0.2ꢀ
0.4ꢀ
1.0ꢀ
0.2ꢀ
0.7ꢀ
2
ꢀ
2.5%Pt/Zr
2.5%Pt/Zr
2.5%Pt/Zr
0
0
0
.
7
Al
Al
Al
0
.
.
.
3
5
7
O ꢀ
y
O ꢀ
y
O ꢀ
y
3
ꢀ
.
5
0
4
ꢀ
.
3
0
5ꢀ
2
2.5%Pt/Al O ꢀ
3
2 2
Reactionꢀconditions:ꢀ10%ꢀglycerolꢀsolution;ꢀmcatalyst:mglycerolꢀ=ꢀ1:10;ꢀH ꢀvolume:ꢀ20ꢀmL;ꢀTemperature:ꢀ230ꢀ°C;ꢀTime:ꢀ8ꢀh;ꢀH ꢀpressure:ꢀ6.0ꢀMPa.ꢀ ꢀ
n‐POꢀ=ꢀs‐propanol;ꢀ1,2‐PDꢀ=ꢀ1,2‐propanediol;ꢀi‐POꢀ=ꢀi‐propanol;ꢀ1,3‐PDꢀ=ꢀ1,3‐propanediol;ꢀEGꢀ=ꢀethyleneꢀglycol;ꢀMAꢀ=ꢀmethanol;ꢀEAꢀ=ꢀethanol.ꢀ
ꢀ
ꢀ
ꢀ
glycerolꢀmolecule.ꢀBrønstedꢀacidꢀsitesꢀareꢀmoreꢀadvantageousꢀ
thanꢀLewisꢀacidꢀsitesꢀforꢀtheꢀselectiveꢀconversionꢀofꢀglycerolꢀtoꢀ
2.5%Pt/Zr0.3Al0.7
O
y
ꢀ(Tableꢀ3,ꢀentriesꢀ4ꢀandꢀ5),ꢀtheꢀselectivityꢀforꢀ
1,2‐propanediolꢀ wasꢀ higherꢀ thanꢀ thatꢀ forꢀ n‐propanol.ꢀ Theꢀ
presenceꢀ ofꢀ 1,2‐propanediolꢀ mayꢀ beꢀ relatedꢀ toꢀ theꢀ weakꢀ acidꢀ
sitesꢀonꢀtheꢀsurfacesꢀofꢀtheꢀcatalysts.ꢀTheꢀweakꢀacidꢀsitesꢀcouldꢀ
onlyꢀremoveꢀoneꢀhydroxylꢀgroupꢀtoꢀaꢀcertainꢀextent.ꢀTheꢀreac‐
tionꢀ catalyzedꢀ byꢀ thoseꢀ catalystsꢀ whoseꢀ Zr/Alꢀ moleꢀ ratioꢀ isꢀ
1
,3‐propanediol,ꢀasꢀreportedꢀinꢀliteratureꢀ[33].ꢀInꢀorderꢀtoꢀelu‐
cidateꢀ theꢀ reactionꢀ sequenceꢀ ofꢀ glycerolꢀ hydrogenolysis,ꢀ theꢀ
hydrogenolysisꢀ ofꢀ 1,2‐PDꢀ andꢀ 1,3‐PDꢀ overꢀ 2.5%Pt/Zr0.7Al0.3O ꢀ
y
wasꢀ evaluatedꢀ underꢀ conditionsꢀ similarꢀ toꢀ thoseꢀ ofꢀ glycerolꢀ
hydrogenolysis.ꢀTheꢀconversionꢀofꢀ1,2‐PDꢀisꢀmuchꢀhigherꢀthanꢀ
thatꢀ ofꢀ 1,3‐PDO.ꢀ 1,2‐PDꢀ wasꢀ efficientlyꢀ transformedꢀ toꢀ yieldꢀ
n‐PDꢀandꢀi‐PD.ꢀItꢀisꢀconfirmedꢀthatꢀpropanediolsꢀcanꢀundergoꢀ
furtherꢀsequentialꢀhydrogenolysisꢀtoꢀformꢀn‐PDꢀandꢀi‐PD.ꢀWhenꢀ
dehydrationꢀoccursꢀatꢀtheꢀcentralꢀhydroxylꢀgroupꢀofꢀ1,2‐PDꢀorꢀ
theꢀ terminalꢀ hydroxylꢀ groupꢀ ofꢀ 1,3‐PD,ꢀ propanalꢀ isꢀ producedꢀ
andꢀ subsequentlyꢀ hydrogenatesꢀ toꢀ formꢀ n‐PO.ꢀ Inꢀ contrast,ꢀ
whenꢀ dehydrationꢀ occursꢀ atꢀ theꢀ terminalꢀ hydroxylꢀ groupꢀ ofꢀ
moreꢀthanꢀ1:1,ꢀsuchꢀasꢀ2.5%Pt/Zr0.5Al0.5
O
y
,ꢀ2.5%Pt/Zr0.7Al0.3O ,ꢀ
y
andꢀ2.5%Pt/ZrO ,ꢀexhibitedꢀhigherꢀselectivityꢀforꢀpropanol;ꢀtheꢀ
2
selectivityꢀ forꢀ propanolꢀ (n‐propanolꢀ +ꢀ i‐propanol)ꢀ wasꢀ moreꢀ
thanꢀ87%.ꢀCombiningꢀtheseꢀresults,ꢀitꢀwasꢀconcludedꢀthatꢀtheseꢀ
threeꢀcatalystsꢀhadꢀaꢀlargeꢀnumberꢀofꢀstrongꢀacidꢀsitesꢀ(Tableꢀ
2).ꢀTheꢀhigherꢀselectivityꢀforꢀpropanolꢀmayꢀbeꢀascribedꢀtoꢀtheꢀ
strongꢀ dehydrationꢀ propertiesꢀ ofꢀ theꢀ strongꢀ acidꢀ sites.ꢀ Thisꢀ
phenomenonꢀ indicatesꢀ thatꢀ theꢀ acidityꢀ ofꢀ catalystꢀ surfaceꢀ af‐
fectsꢀ theꢀ degreeꢀ ofꢀ dehydroxylationꢀ inꢀ glycerol.ꢀ Strongꢀ acidsꢀ
promoteꢀ theꢀ deepꢀ dehydrationꢀ ofꢀ glycerolꢀ toꢀ formꢀ greaterꢀ
quantitiesꢀofꢀpropanol;ꢀthisꢀresultꢀcorrelatesꢀwellꢀwithꢀpreviousꢀ
studiesꢀ[31].ꢀ
1
,2‐PDO,ꢀacetoneꢀisꢀproduced,ꢀwhichꢀisꢀthenꢀfurtherꢀhydrogen‐
atedꢀ toꢀ yieldꢀ i‐PO.ꢀ Meanwhile,ꢀ highꢀ selectivitiesꢀ forꢀ i‐POꢀ andꢀ
,2‐PDꢀ couldꢀ beꢀ foundꢀ onꢀ Pt/Zr0.5Al0.5
,ꢀ
1
O
y
ꢀ andꢀ Pt/Zr0.3Al0.7
O
y
respectively,ꢀindicatingꢀthatꢀaꢀproperꢀbalanceꢀofꢀstrong,ꢀmoder‐
ate,ꢀandꢀweaklyꢀacidicꢀsitesꢀisꢀresponsibleꢀforꢀtheꢀselectiveꢀhy‐
drogenolysisꢀofꢀglycerolꢀtoꢀi‐POꢀorꢀ1,2‐PD.ꢀEthyleneꢀglycolꢀcanꢀ
alsoꢀ beꢀ obtainedꢀ byꢀ glycerolꢀ hydrogenolysis.ꢀ However,ꢀ itꢀ wasꢀ
notꢀ detectedꢀ inꢀ 1,2‐PDꢀ andꢀ 1,3‐PDꢀ hydrogenolysis,ꢀ indicatingꢀ
thatꢀethyleneꢀglycolꢀwasꢀproducedꢀdirectlyꢀfromꢀglycerolꢀbyꢀaꢀ
C–Cꢀbondꢀcleavageꢀreaction.ꢀDueꢀtoꢀtheꢀreactionꢀbetweenꢀglyc‐
erolꢀ andꢀ 1,2‐PD,ꢀ ethanol,ꢀ whichꢀ mightꢀ beꢀ formedꢀ viaꢀ theꢀ se‐
quentialꢀhydrogenolysisꢀofꢀethyleneꢀglycolꢀorꢀdecompositionꢀofꢀ
Althoughꢀtheꢀtotalꢀvaluesꢀofꢀpropanolꢀ(n‐propanolꢀ+ꢀi‐
panol)ꢀ selectivityꢀ catalyzedꢀ byꢀ 2.5%Pt/Zr0.5Al0.5 ,ꢀ 2.5%Pt/
,ꢀ andꢀ 2.5%Pt/ZrO ꢀ wereꢀ almostꢀ theꢀ same,ꢀ theꢀ
ꢀ
pro‐
O
y
ꢀ
Zr0.7Al0.3O
y
2
n‐propanolꢀselectivityꢀvaluesꢀwereꢀdifferent.ꢀAmongꢀthem,ꢀtheꢀ
maximumꢀ selectivityꢀ forꢀ n‐propanolꢀ (82.7%)ꢀ wasꢀ achievedꢀ
whenꢀ 2.5%Pt/Zr0.7Al0.3
withꢀ theꢀ NH ‐TPDꢀ analysis,ꢀ itꢀ couldꢀ beꢀ observedꢀ thatꢀ theꢀ
ꢀ catalystꢀ exhibitedꢀ theꢀ largestꢀ NH ꢀ desorp‐
y
O ꢀ wasꢀ usedꢀ asꢀ theꢀ catalyst.ꢀ Combinedꢀ
3
2.5%Pt/Zr0.7Al0.3
O
y
3
1
,2‐PDO,ꢀ wasꢀ observed.ꢀ Finally,ꢀ theꢀ otherꢀ product,ꢀ methanol,ꢀ
wasꢀ formedꢀ throughꢀ overhydrogenolysisꢀ orꢀ decompositionꢀ
reactions.ꢀ Whenꢀusingꢀ 2.5%Pt/ZrO
ꢀasꢀtheꢀcatalyst,ꢀtheꢀ selec‐
tionꢀpeakꢀatꢀaroundꢀ580ꢀ°C.ꢀThisꢀindicatedꢀthatꢀtheꢀselectivityꢀofꢀ
n‐propanolꢀmayꢀbeꢀassociatedꢀwithꢀtheꢀacidꢀsitesꢀatꢀ580ꢀ°C.ꢀFig.ꢀ
6.ꢀ showsꢀtheꢀrelationshipꢀ betweenꢀn‐propanolꢀ selectivityꢀ andꢀ
2
tivityꢀofꢀn‐propanolꢀwasꢀ75.4%,ꢀwhileꢀglycerolꢀconversionꢀwasꢀ
onlyꢀ26.4%.ꢀByꢀAlꢀdopingꢀofꢀtheꢀ support,ꢀtheꢀconversionꢀandꢀ
selectivityꢀofꢀtheꢀreactionsꢀcouldꢀbeꢀaltered.ꢀInꢀorderꢀtoꢀfurtherꢀ
analyzeꢀtheꢀeffectꢀofꢀaluminumꢀcontentꢀonꢀglycerolꢀconversion,ꢀ
glycerolꢀconversionꢀandꢀtheꢀacidꢀamountsꢀofꢀdifferentꢀcatalystsꢀ
wereꢀcalculated,ꢀasꢀshownꢀinꢀFig.ꢀ5.ꢀItꢀwasꢀfoundꢀthatꢀglycerolꢀ
conversionꢀ increasedꢀ withꢀ anꢀ increaseꢀ inꢀ theꢀ amountꢀ ofꢀ theꢀ
totalꢀacidꢀsitesꢀonꢀtheꢀcatalysts.ꢀSomeꢀstudiesꢀpointedꢀoutꢀthatꢀ
acidꢀ sitesꢀ canꢀ promoteꢀ theꢀ dehydrationꢀ ofꢀ glycerolꢀ [18,31].ꢀ
Hence,ꢀ theꢀ increaseꢀ observedꢀ inꢀ glycerolꢀ conversionꢀ byꢀ in‐
creasingꢀtheꢀaluminumꢀcontentꢀwasꢀattributedꢀtoꢀtheꢀimprove‐
mentꢀinꢀsurfaceꢀacidity.ꢀWhenꢀAl/Zrꢀwasꢀmoreꢀthanꢀ1:1,ꢀglycer‐
olꢀconversionꢀwasꢀnoꢀlongerꢀpromoted;ꢀthisꢀobservationꢀcanꢀbeꢀ
attributedꢀtoꢀotherꢀfactors,ꢀsuchꢀasꢀtemperature,ꢀglycerolꢀcon‐
centration,ꢀhydrogenꢀcontent,ꢀandꢀtheꢀnumberꢀofꢀactiveꢀsites.ꢀ
3
9
3
8
8
3
Pt/Al O3
Pt/Zr0.3Al0.7Oy
2
Pt/Zr0.5Al0.5Oy
34
Pt/Zr0.7Al0.3O
y
26
Pt/ZrO2
2
3
4
5
6
Total acid sites (mmol/g)
Fig.ꢀ 5.ꢀ Relationshipꢀ betweenꢀ glycerolꢀ conversionꢀ andꢀ theꢀ totalꢀ acidꢀ
Asꢀ forꢀ theꢀ reactionsꢀ catalyzedꢀ byꢀ 2.5%Pt/Al
2 3
O ꢀ andꢀ
amountꢀonꢀtheꢀcatalystꢀsurfaces.ꢀ

1126ꢀ
ChuangꢀLiꢀetꢀal.ꢀ/ꢀChineseꢀJournalꢀofꢀCatalysisꢀ39ꢀ(2018)ꢀ1121–1128ꢀ
83

Pt/Zr0.3Al0.7
O
y
 Pt Particles
Orthorhombic ZrO2






used 5 times


54
Pt/Zr0.5Al0.5O
y
4
2
6
Pt/Zr0.7Al0.3O
y
3
2 3
Pt/Al O
fresh
20
38
53
91
580 C strong acid fraction (%)
Fig.ꢀ 6.ꢀ Relationshipꢀ betweenꢀ theꢀ selectivityꢀ forꢀ n‐propanolꢀ andꢀ the
percentageꢀofꢀacidꢀsitesꢀwhoseꢀNH3ꢀdesorptionꢀpeakꢀisꢀaroundꢀ580ꢀ°C.ꢀ
10
20
30
40
50
)
60
70
80
90
o
2 (
3
theꢀpercentageꢀofꢀacidꢀsitesꢀwhoseꢀNH ꢀdesorptionꢀtemperatureꢀ
Fig.ꢀ8.ꢀXRDꢀpatternsꢀofꢀfreshꢀandꢀusedꢀ2.5%Pt/Zr0.7Al0.3O ꢀcatalysts.ꢀ
y
isꢀ aroundꢀ 580ꢀ °C.ꢀ Itꢀ wasꢀ foundꢀ thatꢀ theꢀ selectivityꢀ forꢀ
n‐propanolꢀ wasꢀ almostꢀ linearlyꢀ relatedꢀ toꢀ theꢀ percentageꢀ ofꢀ
acids.ꢀSomeꢀresearchersꢀalsoꢀpointedꢀoutꢀthatꢀn‐propanolꢀselec‐
tivityꢀwasꢀrelatedꢀtoꢀstrongꢀacidꢀsitesꢀofꢀaꢀspecificꢀintensityꢀonꢀ
theꢀcatalystꢀ[10].ꢀTheꢀlocationꢀcorrespondsꢀtoꢀaꢀspecificꢀacidꢀsiteꢀ
thatꢀ isꢀ beneficialꢀ forꢀ theꢀ transformationꢀ ofꢀ glycerolꢀ toꢀ
n‐propanolꢀonꢀtheꢀcatalyst.ꢀ
7
.ꢀAfterꢀbeingꢀusedꢀforꢀ5ꢀtimes,ꢀtheꢀcatalystꢀstillꢀledꢀtoꢀalmostꢀ
theꢀsameꢀglycerolꢀconversionꢀpercentage.ꢀHowever,ꢀtheꢀselec‐
tivityꢀofꢀn‐propanolꢀdecreasedꢀslightly,ꢀwhileꢀthatꢀofꢀi‐propanolꢀ
beganꢀtoꢀincrease.ꢀ
Inꢀ orderꢀ toꢀ explainꢀ theseꢀ phenomena,ꢀ theꢀ catalystꢀ usedꢀ 5ꢀ
timesꢀwasꢀanalyzedꢀbyꢀXRDꢀandꢀNH
Fig.ꢀ8ꢀandꢀFig.ꢀ9,ꢀrespectively).ꢀItꢀcanꢀbeꢀclearlyꢀobservedꢀthatꢀ
theꢀXRDꢀpeaksꢀofꢀtheꢀ2.5%Pt/Zr0.7Al0.3 ꢀcatalystꢀareꢀveryꢀdif‐
ferentꢀ fromꢀ thoseꢀ ofꢀ theꢀ catalystꢀ usedꢀ 5ꢀ times;ꢀ peaksꢀ corre‐
spondingꢀ toꢀ orthorhombicꢀ ZrO ꢀ (JCPDSꢀ No.ꢀ 34‐1084)ꢀ wereꢀ
observableꢀinꢀtheꢀXRDꢀpatternꢀofꢀtheꢀcatalystꢀusedꢀ5ꢀtimes.ꢀNoꢀ
apparentꢀleachingꢀofꢀPtꢀandꢀAlꢀcouldꢀbeꢀdetectedꢀinꢀtheꢀresidualꢀ
solutionꢀbyꢀinductivelyꢀcoupledꢀplasma‐atomicꢀemissionꢀspec‐
troscopyꢀ (ICP‐AES)ꢀ thoughꢀ partiallyꢀ orthorhombicꢀ ZrO ꢀsepa‐
ratedꢀoutꢀfromꢀtheꢀZr‐Alꢀcompositeꢀoxide,ꢀwhichꢀmayꢀdueꢀtoꢀtheꢀ
calcinationꢀofꢀtheꢀcatalystꢀandꢀreductionꢀatꢀhighꢀtemperatures.ꢀ
AsꢀshownꢀinꢀtheꢀNH ‐TPDꢀresults,ꢀtheꢀtotalꢀnumberꢀofꢀacidꢀsitesꢀ
wereꢀalmostꢀsimilarꢀforꢀtheꢀfreshꢀandꢀusedꢀcatalysts,ꢀ2.87ꢀandꢀ
3
‐TPDꢀanalysesꢀ(shownꢀinꢀ
Basedꢀ onꢀ theꢀ resultsꢀ describedꢀ above,ꢀ 2.5%Pt/Zr0.7Al0.3O ꢀ
y
wasꢀchosenꢀasꢀtheꢀcatalystꢀtoꢀexamineꢀtheꢀinfluenceꢀofꢀreactionꢀ
conditions,ꢀ suchꢀ asꢀ hydrogenꢀ content,ꢀ reactionꢀ temperature,ꢀ
andꢀreactionꢀtime,ꢀonꢀtheꢀglycerolꢀhydrogenolysisꢀreaction.ꢀTheꢀ
resultsꢀareꢀincludedꢀinꢀtheꢀSupportingꢀInformation.ꢀTheꢀresultsꢀ
O
y
2
showedꢀthatꢀanꢀincreaseꢀinꢀtheꢀH ꢀamount,ꢀreactionꢀtempera‐
2
ture,ꢀorꢀreactionꢀtimeꢀcouldꢀsignificantlyꢀpromoteꢀtheꢀconver‐
sionꢀofꢀglycerol.ꢀAboutꢀ81.2%ꢀofꢀglycerolꢀconversionꢀandꢀ86.3%ꢀ
ofꢀ n‐propanolꢀ selectivityꢀ wereꢀ obtainedꢀ underꢀ theꢀ reactionꢀ
2
conditionsꢀofꢀ240ꢀ°C,ꢀ8ꢀh,ꢀandꢀ35ꢀmLꢀH
2
.ꢀ
Toꢀevaluateꢀtheꢀreusabilityꢀofꢀtheꢀ2.5%Pt/Zr0.7Al0.3O ꢀcata‐
y
3
lyst,ꢀtheꢀusedꢀcatalystꢀwasꢀfirstꢀwashedꢀseveralꢀtimesꢀwithꢀde‐
ionizedꢀwaterꢀandꢀthenꢀcalcinedꢀinꢀaꢀtubeꢀfurnaceꢀatꢀ300ꢀ°Cꢀforꢀ
2
ꢀh,ꢀfollowedꢀbyꢀreductionꢀinꢀH ꢀflowꢀatꢀ350ꢀ°Cꢀforꢀ4ꢀh.ꢀLater,ꢀtheꢀ
2
catalystꢀwasꢀusedꢀforꢀaꢀsecondꢀroundꢀunderꢀtheꢀsameꢀreactionꢀ
conditions.ꢀTheꢀresultsꢀofꢀreusabilityꢀanalysisꢀareꢀshownꢀinꢀFig.ꢀ
used 5 times
8
6
4
2
4
4
Conversion
1
00
1
,3-PD
,2-PD
1
8
6
4
0
0
0
i-propanol
n-propanol
40
0
36
fresh
1
5
0
5
0
32
1
00
1
28
5
0
24
1
2
3
4
5
Cycle times
0
Fig.ꢀ7.ꢀReusabilityꢀofꢀ2.5%Pt/Zr0.7Al0.3
olysis.ꢀReactionꢀconditions:ꢀ10%ꢀglycerolꢀsolution;ꢀmcatalyst:mglycerolꢀ=ꢀ1:10
ꢀ volume:ꢀ 20ꢀ mL;ꢀ Temperature:ꢀ 230ꢀ °C;ꢀ Time:ꢀ 8ꢀ h;ꢀ H ꢀ pressure:ꢀ
.0MPa.ꢀ
O
y
ꢀcatalystꢀforꢀglycerolꢀhydrogen‐
2
00
400
Temperature ( C)
600
800
o
H
6
2
2
Fig.ꢀ9.ꢀNH
3
‐TPDꢀprofilesꢀofꢀfreshꢀandꢀusedꢀ2.5%Pt/Zr0.7Al0.3O ꢀcatalysts.
y

ꢀ
ChuangꢀLiꢀetꢀal.ꢀ/ꢀChineseꢀJournalꢀofꢀCatalysisꢀ39ꢀ(2018)ꢀ1121–1128ꢀ
1127ꢀ
2.81ꢀmmol/g,ꢀrespectively.ꢀHowever,ꢀtheꢀacidꢀsiteꢀdistributionꢀ
[4] L.ꢀZ.ꢀQin,ꢀM.ꢀJ.ꢀSong,ꢀC.ꢀL.ꢀChen,ꢀGreenꢀChem.,ꢀ2010,ꢀ12,ꢀ1466–1472.ꢀ
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GraphicalꢀAbstractꢀ
Chin.ꢀJ.ꢀCatal.,ꢀ2018,ꢀ39:ꢀ1121–1128ꢀ ꢀ ꢀ doi:ꢀ10.1016/S1872‐2067(18)63068‐2
Glycerolꢀhydrogenolysisꢀtoꢀn‐propanolꢀoverꢀZr‐Alꢀcompositeꢀ ꢀ
oxide‐supportedꢀPtꢀcatalystsꢀ
Sel > 86%
ChuangꢀLi,ꢀBoꢀHe,ꢀYuꢀLing,ꢀChi‐WingꢀTsang,ꢀChanghaiꢀLiangꢀ*ꢀ
DalianꢀUniversityꢀofꢀTechnology;ꢀ ꢀ
TechnologicalꢀandꢀHigherꢀEducationꢀInstituteꢀofꢀHongꢀKongꢀ
ꢀ
ꢀ
Zr‐Alꢀ mixedꢀ oxide‐supportedꢀ Ptꢀ catalystsꢀ withꢀ differentꢀ Zr/Alꢀ moleꢀ
ratiosꢀwereꢀsynthesizedꢀbyꢀanꢀimpregnationꢀmethodꢀandꢀusedꢀinꢀtheꢀ
selectiveꢀhydrogenolysisꢀofꢀglycerolꢀtoꢀn‐propanolꢀwithꢀhighꢀactivity,ꢀ
selectivity,ꢀandꢀabsoluteꢀreusability.ꢀ

1128ꢀ
ChuangꢀLiꢀetꢀal.ꢀ/ꢀChineseꢀJournalꢀofꢀCatalysisꢀ39ꢀ(2018)ꢀ1121–1128ꢀ
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Zr-Al复合氧化物负载Pt催化甘油氢解制正丙醇
a
a
a
b
a,*
李 闯 , 何 博 , 凌 雨 , 曾志荣 , 梁长海
a
大连理工大学化工学院先进材料和催化工程实验室, 辽宁大连116024
b
香港高等教育科技学院, 科技学院, 香港50011
摘要: 近年来, 甘油氢解的研究主要集中在生成 1,2-丙二醇和1,3-丙二醇二元醇. 与二元醇相比, 正丙醇也是一种昂贵的化
学品, 用过量的甘油直接氢解合成高选择性的正丙醇将是一个非常好的生产途径. 因为铂金属具有较强的断 C‒O 键的能
力, 所以甘油氢解制正丙醇的催化剂主要采用铂作为活性组分. 本文以铂为活性组分, 采用浸渍法将其负载到不同 Zr/Al
比的 Zr-Al 复合氧化物上制得 2.5%Pt/Zr
醇反应性能的影响.
x y
Al1-xO 催化剂, 并将其应用到甘油氢解反应中, 探讨了 Zr/Al 比对甘油氢解制正丙
o
表征结果发现, 锆铝混合氧化物经过 400 C 焙烧后为无定形态的复合金属氧化物, 载体中无单相氧化锆或氧化铝存
在. 随着锆含量增加, 催化剂酸性位点向强酸方向移动. 不同 Zr/Al 比的锆铝混合氧化物负载铂催化剂的评价结果发现, 甘
油转化率随催化剂中铝含量增加而增大; 锆铝比大于 5:5 时, 丙醇 (正丙醇+异丙醇) 的选择性很高, 普遍大于 87%; 锆铝比
2
至 7:3 时, 正丙醇选择性最高. 通过 X 射线衍射、CO 化学吸附、H 程序升温还原、吡啶吸附、氨气程序升温脱附等方法
对催化剂进行了表征, 发现随着锆铝混合氧化物中锆含量的增加, 催化剂的酸性位点向强酸方向移动, 调变 Zr/Al 比促进了
铂颗粒的分散, 实现了催化剂表面酸量和强酸位点的定向调控. 当锆铝比增加至 7:3 时, 催化剂的强酸位点占总酸含量的
9
1.2%. 对比催化剂酸性分析和反应结果可知, 催化剂表面的总酸含量高有助于甘油转化; 强酸位点有助于甘油深度脱水
o
生成丙醇; 正丙醇的选择性则可能与 NH
3
脱附温度在 580 C 处的强酸位和较大的 Pt 颗粒有关. 当 Zr/Al 比为 7:3 时, 催
化剂表面强酸位点占 91.2%, 而强酸位点的增加有助于甘油的深度脱水形成正丙醇. 因此, 以 10% 甘油水溶液为原料, 在
o
2
40 C和6.0 MPa 初始氢气压力条件下反应 8 h, 甘油转化率和正丙醇的选择性分别达到 81.2% 和 86.3%. 催化剂经过 5 次
循环使用后, 甘油转化率和丙醇 (正丙醇+异丙醇) 选择性几乎不变, 但正丙醇的选择性略有降低. 使用 5 次后的催化剂表
面的总酸量变化不大, 但酸分布变化较大, 即强酸比例下降. 可见, 催化剂活性变化小是由于其表面酸量变化不大, 而正丙
醇选择性下降与强酸位点比例下降有关.
关键词: 甘油氢解; 正丙醇; 铂催化剂; 锆铝复合氧化物; 锆/铝比
收稿日期: 2018-01-29. 接受日期: 2018-03-22. 出版日期: 2018-06-05.
*
通讯联系人. 电话/传真: (0411)84986353; 电子信箱: changhai@dlut.edu.cn
基 金 来 源 : 国 家 自 然 科 学 基 金 (21573031, 21373038); 大 连 市 优 秀 人 才 支 持 计 划 (2016RD09); 辽 宁 省 博 士 启 动 基 金
20170520395).
本文的电子版全文由Elsevier出版社在ScienceDirect上出版(http://www.sciencedirect.com/science/journal/18722067).
(