Highly active Cu/SiO2 catalysts for hydrogenation of diethyl malonate to 1,3-propanediol

Article abstract of DOI:10.1016/S1872-2067(15)61053-1

Cu/SiO₂ catalysts prepared by the ammonia evaporation method were applied to hydrogenation of diethyl malonate to 1,3-propanediol. The calcination temperature played an important role in the structural evolution and catalytic performance of the Cu/SiO₂ catalysts, which were systematically characterized by N₂ adsorption-desorption, inductively coupled plasma-atomic emission spectroscopy, N₂O chemisorption, X-ray diffraction, Fourier transform infrared spectroscopy, H₂ temperature-programmed reduction, transmission electron microscopy, and X-ray photoelectron spectroscopy. When the Cu/SiO₂ catalyst was calcined at 723 K, 90.7% conversion of diethyl malonate and 32.3% selectivity of 1,3-propanediol were achieved. Compared with Cu/SiO₂ catalysts calcined at other temperatures, the enhanced catalytic performance of the Cu/SiO₂ catalyst calcined at 723 K can be attributed to better dispersion of copper species, larger cupreous surface area and greater amount of copper phyllosilicate, which results in a higher ratio of Cu⁺/Cu⁰. The synergetic effect of Cu⁰ and Cu⁺ is suggested to be responsible for the optimum activity.

Full text of DOI:10.1016/S1872-2067(15)61053-1

ChineseꢀJournalꢀofꢀCatalysisꢀ37ꢀ(2016)ꢀ484–493
ꢀ
ꢀ ꢀ ꢀ
ꢀ ꢀ ꢀ ꢀ
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
HighlyꢀactiveꢀCu/SiO ꢀcatalystsꢀforꢀhydrogenationꢀofꢀdiethylꢀ ꢀ
2
malonateꢀtoꢀ1,3‐propanediolꢀ
ꢀ
TongmeiꢀDing,ꢀHengshuiꢀTian*,ꢀJichangꢀLiu,ꢀWenbinꢀWu,ꢀJintaoꢀYu
ꢀ
SchoolꢀofꢀChemicalꢀEngineering,ꢀEastꢀChinaꢀUniversityꢀofꢀScienceꢀandꢀTechnology,ꢀShanghaiꢀ200237,ꢀChinaꢀ
A R T I C L E ꢀ I N F O ꢀ
A B S T R A C T ꢀ
Articleꢀhistory:ꢀ
Cu/SiO
diethylꢀmalonateꢀtoꢀ1,3‐propanediol.ꢀTheꢀcalcinationꢀtemperatureꢀplayedꢀanꢀimportantꢀroleꢀinꢀtheꢀ
structuralꢀevolutionꢀandꢀcatalyticꢀperformanceꢀofꢀtheꢀCu/SiO ꢀcatalysts,ꢀwhichꢀwereꢀsystematicallyꢀ
characterizedꢀbyꢀN ꢀadsorption‐desorption,ꢀinductivelyꢀcoupledꢀplasma‐atomicꢀemissionꢀspectros‐
copy,ꢀN Oꢀchemisorption,ꢀX‐rayꢀdiffraction,ꢀFourierꢀtransformꢀinfraredꢀspectroscopy,ꢀH ꢀtempera‐
ture‐programmedꢀreduction,ꢀtransmissionꢀelectronꢀmicroscopy,ꢀandꢀX‐rayꢀphotoelectronꢀspectros‐
copy.ꢀWhenꢀtheꢀCu/SiO ꢀcatalystꢀwasꢀcalcinedꢀatꢀ723ꢀK,ꢀ90.7%ꢀconversionꢀofꢀdiethylꢀmalonateꢀandꢀ
2.3%ꢀselectivityꢀofꢀ1,3‐propanediolꢀwereꢀachieved.ꢀComparedꢀwithꢀCu/SiO ꢀcatalystsꢀcalcinedꢀatꢀ
otherꢀtemperatures,ꢀtheꢀenhancedꢀcatalyticꢀperformanceꢀofꢀtheꢀCu/SiO ꢀcatalystꢀcalcinedꢀatꢀ723ꢀK
canꢀbeꢀattributedꢀtoꢀbetterꢀdispersionꢀofꢀcopperꢀspecies,ꢀlargerꢀcupreousꢀsurfaceꢀareaꢀandꢀgreaterꢀ
2
ꢀcatalystsꢀpreparedꢀbyꢀtheꢀammoniaꢀevaporationꢀmethodꢀwereꢀappliedꢀtoꢀhydrogenationꢀofꢀ
Receivedꢀ3ꢀDecemberꢀ2015ꢀ
Acceptedꢀ13ꢀFebruaryꢀ2016ꢀ
Publishedꢀ5ꢀAprilꢀ2016ꢀ
2
2
2
2
Keywords:ꢀ
Copperꢀ
Silicaꢀ
Diethylꢀmalonateꢀ
Hydrogenationꢀ
2
3
2
2
+
0
amountꢀofꢀcopperꢀphyllosilicate,ꢀwhichꢀresultsꢀinꢀaꢀhigherꢀratioꢀofꢀCu /Cu .ꢀTheꢀsynergeticꢀeffectꢀof
1,3‐Propanediolꢀ
0
+
Cu ꢀandꢀCu ꢀisꢀsuggestedꢀtoꢀbeꢀresponsibleꢀforꢀtheꢀoptimumꢀactivity.ꢀ
ꢀ2016,ꢀDalianꢀInstituteꢀofꢀChemicalꢀPhysics,ꢀChineseꢀAcademyꢀofꢀSciences.
Calcinationꢀtemperatureꢀ
©
PublishedꢀbyꢀElsevierꢀB.V.ꢀAllꢀrightsꢀreserved.
1
.ꢀ ꢀ Introductionꢀ
Copperꢀ sitesꢀ accountꢀ forꢀ selectiveꢀ hydrogenationꢀ ofꢀ C–Oꢀ
bondsꢀ andꢀ areꢀ inactiveꢀ forꢀ hydrogenolysisꢀ ofꢀ C–Cꢀ bonds,ꢀ soꢀ
Cu‐basedꢀ catalystsꢀ haveꢀ beenꢀ recentlyꢀ investigatedꢀ forꢀ va‐
por‐phaseꢀ hydrogenationꢀ reactionsꢀ [11].ꢀ Theꢀ typicalꢀ applica‐
tionꢀofꢀCu‐basedꢀcatalystꢀisꢀhydrogenationꢀofꢀdimethylꢀoxalateꢀ
(DMO)ꢀtoꢀethyleneꢀglycolꢀ[12–16].ꢀAmongꢀtheꢀvariousꢀreportedꢀ
catalysts,ꢀsilica‐supportedꢀCuꢀcatalystsꢀhaveꢀwidespreadꢀappli‐
cationsꢀ inꢀ thisꢀ areaꢀ becauseꢀ ofꢀ theꢀ moderateꢀ interactionꢀ be‐
tweenꢀcopperꢀandꢀtheꢀsilicaꢀsupport,ꢀwhichꢀhasꢀrelativelyꢀweakꢀ
acidityꢀ andꢀ isꢀ favorableꢀ forꢀ constructingꢀ catalyticꢀ activeꢀ sitesꢀ
[17–19].ꢀ Inꢀ addition,ꢀ mesoporousꢀ materialsꢀ suchꢀ asꢀ MCM‐41ꢀ
[20,21],ꢀ hexagonalꢀ mesoporousꢀ silicaꢀ [22],ꢀ andꢀ SBA‐15ꢀ [23]ꢀ
haveꢀbeenꢀusedꢀasꢀsupports.ꢀHowever,ꢀtheꢀpreparationꢀprocessꢀ
1,3‐Propanediolꢀ (1,3‐PDO),ꢀ whichꢀ hasꢀ transformedꢀ fromꢀ aꢀ
traditionalꢀspecialtyꢀchemicalꢀtoꢀaꢀcommodityꢀchemicalꢀ[1],ꢀisꢀ
widelyꢀ usedꢀ inꢀ polyesterꢀ fibers,ꢀ resins,ꢀ cosmetics,ꢀ lubricantsꢀ
andꢀengineꢀcoolantsꢀ[2–5].ꢀOleochemicalꢀsynthesisꢀprocessesꢀofꢀ
1,3‐PDOꢀuseꢀethyleneꢀoxideꢀ[6,7]ꢀorꢀacroleinꢀasꢀfeedstocksꢀ[8,9].ꢀ
Theꢀmainꢀproblemꢀliesꢀinꢀresidualꢀcarbonylsꢀtoꢀtheꢀextentꢀofꢀaꢀ
fewꢀ thousandꢀ partsꢀ perꢀ million,ꢀ whichꢀ isꢀ extremelyꢀ trouble‐
someꢀ inꢀ theꢀ productionꢀ ofꢀ polytrimethyleneꢀ terephthalateꢀ
(PTT).ꢀAꢀsynthesisꢀprocessꢀinvolvingꢀhydrogenationꢀofꢀdiethylꢀ
malonateꢀ(DEM)ꢀtoꢀ1,3‐PDOꢀhasꢀbeenꢀdiscussedꢀinꢀdetailꢀandꢀ
couldꢀpreventꢀthisꢀproblem.ꢀWangꢀetꢀal.ꢀ[10]ꢀreportedꢀthatꢀDEMꢀ
conversionꢀcouldꢀreachꢀ55.9%ꢀatꢀ6.7ꢀMPaꢀoverꢀCuZn
a b c
Al O ꢀcat‐
ofꢀ theseꢀ mesoporousꢀ supportsꢀ isꢀ complicatedꢀ andꢀ time‐
ꢀ
con‐
alysts.ꢀHowever,ꢀtheꢀrelationshipsꢀbetweenꢀtheꢀcatalystꢀstruc‐
tureꢀandꢀperformance,ꢀandꢀtheꢀcatalystꢀlifeꢀandꢀitsꢀdeactivationꢀ
haveꢀnotꢀbeenꢀinvestigated.ꢀ
suming.ꢀCu/SiO ꢀhasꢀbeenꢀintensivelyꢀinvestigatedꢀandꢀattract‐
edꢀ considerableꢀ attentionꢀ owingꢀ toꢀ itsꢀ excellentꢀ selectivity,ꢀ
greenꢀ benefitsꢀ andꢀ lowꢀ cost.ꢀ Variousꢀ preparationꢀ techniquesꢀ
2
*ꢀCorrespondingꢀauthor.ꢀTel:ꢀ+86‐21‐64252198;ꢀE‐mail:ꢀhstian@ecust.edu.cnꢀ
DOI:ꢀ10.1016/S1872‐2067(15)61053‐1ꢀ|ꢀhttp://www.sciencedirect.com/science/journal/18722067ꢀ|ꢀChin.ꢀJ.ꢀCatal.,ꢀVol.ꢀ37,ꢀNo.ꢀ4,ꢀAprilꢀ2016ꢀ ꢀ ꢀ

ꢀ
TongmeiꢀDingꢀetꢀal.ꢀ/ꢀChineseꢀJournalꢀofꢀCatalysisꢀ37ꢀ(2016)ꢀ484–493ꢀ
485ꢀ
2
haveꢀbeenꢀusedꢀtoꢀfabricateꢀCu/SiO ꢀcatalyst,ꢀsuchꢀasꢀammoniaꢀ
meshes.ꢀTheꢀcatalystsꢀareꢀdenotedꢀasꢀCu/SiO
2
‐T,ꢀwhereꢀTꢀisꢀtheꢀ
evaporation,ꢀ ionꢀ exchange,ꢀ sol‐gelꢀ processes,ꢀ depositionꢀ pre‐
cipitation,ꢀandꢀimpregnationꢀ[24].ꢀNotably,ꢀtheꢀammoniaꢀevap‐
orationꢀ methodꢀ canꢀ effectivelyꢀ disperseꢀ copperꢀ andꢀ provideꢀ
highꢀcopperꢀloadingꢀonꢀtheꢀsupport.ꢀ
calcinationꢀtemperatureꢀ(K).ꢀ
2.2.ꢀ ꢀ Catalystꢀcharacterizationꢀ
Copperꢀ speciesꢀ undergoꢀ complicatedꢀ changesꢀ duringꢀ theꢀ
ammoniaꢀ evaporationꢀ process.ꢀ Theꢀ preparationꢀ conditions,ꢀ
suchꢀ asꢀ theꢀ initialꢀ precipitationꢀ temperatureꢀ [25],ꢀ Cuꢀ loadingꢀ
Copperꢀloadingꢀofꢀallꢀcatalystsꢀwasꢀdeterminedꢀbyꢀtheꢀinduc‐
tivelyꢀcoupledꢀplasma–atomicꢀemissionꢀspectroscopyꢀ(ICP‐AES)ꢀ
methodꢀ (Agilentꢀ725ES,ꢀUSA).ꢀ Samplesꢀ wereꢀ dissolvedꢀinꢀ HF,ꢀ
andꢀthenꢀdilutedꢀwithꢀwater.ꢀ ꢀ
[26],ꢀ ammoniaꢀ evaporationꢀ temperatureꢀ [27],ꢀ andꢀ amountꢀ ofꢀ
ammoniaꢀ [28]ꢀ haveꢀ aꢀ profoundꢀ effectꢀ onꢀ Cuꢀ dispersion,ꢀ theꢀ
Nitrogenꢀ adsorption–desorptionꢀ isothermsꢀ atꢀ 77ꢀ Kꢀ wereꢀ
measuredꢀ withꢀ aꢀ Micromeriticsꢀ ASAPꢀ 2020ꢀ instrumentꢀ afterꢀ
degassingꢀatꢀ423ꢀKꢀforꢀ1ꢀhꢀinꢀvacuumꢀtoꢀremoveꢀphysicallyꢀad‐
sorbedꢀimpurities.ꢀTheꢀspecificꢀsurfaceꢀareaꢀwasꢀcalculatedꢀbyꢀ
0
+
Cu /Cu ꢀ ratio,ꢀ andꢀ theꢀ interactionꢀ betweenꢀ copperꢀ andꢀ silica.ꢀ
TheꢀeffectꢀofꢀtheꢀcalcinationꢀtemperatureꢀonꢀDMOꢀhydrogena‐
tionꢀhasꢀbeenꢀdiscussedꢀbyꢀZhuꢀetꢀal.ꢀ[29].ꢀTheyꢀsuggestedꢀthatꢀ
largeꢀ stableꢀ Cuꢀ particlesꢀ formedꢀ andꢀ theꢀ numberꢀ ofꢀ Cuꢀ sitesꢀ
decreasedꢀunderꢀhighꢀcalcinationꢀtemperature.ꢀTheꢀeffectꢀofꢀtheꢀ
calcinationꢀ temperatureꢀ onꢀ otherꢀ reactionꢀ systemsꢀ hasꢀ alsoꢀ
beenꢀinvestigated.ꢀYuanꢀetꢀal.ꢀ[30]ꢀreportedꢀthatꢀtheꢀcalcinationꢀ
temperatureꢀ significantlyꢀ influencedꢀ theꢀ propertiesꢀ andꢀ per‐
formanceꢀ ofꢀ theꢀ catalyst,ꢀ andꢀ higherꢀ calcinationꢀ temperatureꢀ
causedꢀagglomerationꢀofꢀCuOꢀspeciesꢀinꢀdimethylꢀadipateꢀhy‐
drogenationꢀtoꢀ1,6‐hexanediol.ꢀTheꢀcatalyticꢀactivityꢀofꢀtolueneꢀ
combustionꢀonꢀCu–Mn/MCM‐41ꢀisꢀsignificantlyꢀaffectedꢀbyꢀtheꢀ
calcinationꢀtemperatureꢀ[31].ꢀChoiꢀetꢀal.ꢀ[32]ꢀreportedꢀtheꢀeffectꢀ
ofꢀcalcinationꢀtemperatureꢀonꢀcatalystꢀperformance,ꢀandꢀbetterꢀ
catalyticꢀ stabilityꢀ wasꢀ closelyꢀ relatedꢀ toꢀ formationꢀ ofꢀ nickelꢀ
hydrosilicate.ꢀ Kanekoꢀ etꢀ al.ꢀ [33]ꢀ suggestedꢀ thatꢀ catalystsꢀ cal‐
cinedꢀatꢀmoderateꢀtemperatureꢀgaveꢀtheꢀhighestꢀPtꢀdispersion,ꢀ
furtherꢀenhancingꢀtheꢀactivity.ꢀ
theꢀBrunauer‐Emmett‐Tellerꢀ(BET)ꢀmethod.ꢀTheꢀBarrett‐Joyn‐
ꢀ
er‐Halendaꢀ (BJH)ꢀmethodꢀwasꢀusedꢀtoꢀ calculateꢀtheꢀ poreꢀ sizeꢀ
distributionsꢀaccordingꢀtoꢀtheꢀdesorptionꢀbranchesꢀofꢀtheꢀiso‐
therms.ꢀ
Wide‐angleꢀX‐rayꢀdiffractionꢀ(XRD)ꢀscanningꢀwasꢀperformedꢀ
onꢀaꢀGermanꢀBrukerꢀD8ꢀFOCUSꢀX‐rayꢀdiffractometerꢀoperatingꢀ
withꢀCuꢀK ꢀradiationꢀatꢀ40ꢀkVꢀandꢀ100ꢀmA.ꢀTheꢀangleꢀrangedꢀ
α
fromꢀ10°ꢀtoꢀ80°ꢀwithꢀaꢀcontinuousꢀscanningꢀspeedꢀofꢀ0.02°/min.ꢀ
TheꢀmeanꢀcrystalliteꢀsizesꢀofꢀCuOꢀandꢀCuꢀwereꢀcalculatedꢀwithꢀ
theꢀScherrerꢀequation.ꢀ ꢀ
Fourierꢀ transformꢀ infraredꢀ (FT‐IR)ꢀ spectroscopyꢀ wasꢀ per‐
formedꢀonꢀNicoletꢀ5700ꢀspectrometerꢀ(USA)ꢀwithꢀaꢀKBrꢀbeamꢀ
−1
splitter.ꢀTheꢀspectralꢀresolutionꢀwasꢀ2ꢀcm ꢀandꢀ32ꢀscansꢀwereꢀ
recordedꢀforꢀeachꢀspectrum.ꢀ
Theꢀreducibilityꢀofꢀtheꢀcalcinedꢀsamplesꢀwasꢀdeterminedꢀbyꢀ
Inꢀthisꢀpaper,ꢀCu/SiO
moniaꢀevaporationꢀmethod.ꢀFewꢀstudiesꢀhaveꢀbeenꢀpublishedꢀ
regardingꢀ theꢀ structure–performanceꢀ correlationꢀ ofꢀ Cu/SiO
catalystsꢀ underꢀ differentꢀ calcinationꢀ temperaturesꢀ inꢀ theꢀ hy‐
drogenationꢀ ofꢀ DEMꢀ toꢀ 1,3‐PDO.ꢀ Toꢀ elucidateꢀ theꢀ effect,ꢀ sys‐
2
ꢀcatalystsꢀwereꢀpreparedꢀbyꢀtheꢀam‐
H
2ꢀ temperature‐programmedꢀ reductionꢀ (TPR)ꢀ onꢀ aꢀ Mi‐
cromeriticsꢀ Autochemꢀ IIꢀ ASAPꢀ 2090ꢀ instrument.ꢀ Calcinedꢀ
Cu/SiO ꢀcatalystꢀ(50ꢀmg)ꢀwasꢀoutgassedꢀatꢀ473ꢀKꢀunderꢀArꢀforꢀ1ꢀ
h.ꢀ Afterꢀ theꢀ catalystꢀ wasꢀ cooledꢀ toꢀ roomꢀ temperatureꢀ underꢀ
argon,ꢀ10%ꢀH /Arꢀwasꢀintroducedꢀatꢀaꢀflowꢀrateꢀofꢀ50ꢀmL/minꢀ
2
ꢀ
2
2
tematicꢀ investigationsꢀ ofꢀ theꢀ structureꢀ behaviorꢀ andꢀ catalyticꢀ
performanceꢀwereꢀperformed.ꢀ
andꢀthenꢀtheꢀtemperatureꢀwasꢀlinearlyꢀincreasedꢀfromꢀambientꢀ
temperatureꢀtoꢀ723ꢀKꢀatꢀaꢀrateꢀofꢀ10ꢀK/min.ꢀ
N
2
Oꢀ chemisorptionꢀ wasꢀ carriedꢀ outꢀ inꢀ Autochemꢀ IIꢀ 2920ꢀ
apparatusꢀ (Micromeritics,ꢀ USA).ꢀ Briefly,ꢀ theꢀ catalystꢀ sampleꢀ
wasꢀ reducedꢀ inꢀ 5%ꢀ H /Arꢀ atꢀ 723ꢀ Kꢀ withꢀ aꢀ heatingꢀ rateꢀ ofꢀ 2ꢀ
K/min.ꢀAfterꢀcoolingꢀtoꢀ323ꢀKꢀunderꢀAr,ꢀ10%ꢀN O/Heꢀwasꢀin‐
2
.ꢀ ꢀ Experimentalꢀ
2
2.1.ꢀ ꢀ Catalystꢀpreparationꢀ
2
troducedꢀatꢀaꢀrateꢀofꢀ50ꢀmL/minꢀforꢀ40ꢀmin,ꢀensuringꢀthatꢀsur‐
faceꢀCuꢀatomsꢀwereꢀcompletelyꢀoxidizedꢀaccordingꢀtoꢀtheꢀreac‐
2
Cu/SiO ꢀcatalystsꢀwereꢀpreparedꢀbyꢀtheꢀammoniaꢀevapora‐
tionꢀ method.ꢀ Inꢀ brief,ꢀ 24.16ꢀ gꢀ ofꢀ Cu(NO
3
)
2
·3H Oꢀ (Shanghaiꢀ
2
tionꢀ2ꢀCu(s)ꢀ+ꢀN
surfaceꢀCu OꢀtoꢀmetallicꢀCuꢀwasꢀperformedꢀatꢀ723ꢀKꢀunderꢀ10%ꢀ
/Arꢀtoꢀensureꢀthatꢀchemisorbedꢀoxygenꢀonꢀtheꢀsurfaceꢀim‐
2
Oꢀ →ꢀ Cu
2
O
(s)ꢀ+ꢀN
2
.ꢀHydrogenꢀpulseꢀreductionꢀofꢀ
LingfengꢀChemicalꢀReagentꢀCo.ꢀLtd.,ꢀShanghai,ꢀChina)ꢀwasꢀdis‐
solvedꢀ inꢀ 200ꢀ mLꢀ ofꢀ deionizedꢀ waterꢀ atꢀ 313ꢀ Kꢀ withꢀ vigor‐
ousstirring.ꢀ Ammoniaꢀ solutionꢀ (25ꢀ wt%ꢀ Shanghaiꢀ Lingfengꢀ
Chemicalꢀ Reagentꢀ Co.ꢀLtd.)ꢀ wasꢀ thenꢀaddedꢀ dropwise.ꢀSubse‐
quently,ꢀ64ꢀgꢀofꢀsilicaꢀsolꢀ(JN‐30,ꢀQingdaoꢀOceanꢀChemicalꢀCo.ꢀ
Ltd.,ꢀQingdao,ꢀChina)ꢀwasꢀaddedꢀtoꢀtheꢀcuprammoniaꢀsolutionꢀ
andꢀtheꢀsolutionꢀwasꢀstirredꢀforꢀ4ꢀh.ꢀTheꢀsuspensionꢀwasꢀthenꢀ
heatedꢀinꢀaꢀwaterꢀbathꢀpreheatedꢀtoꢀ363ꢀKꢀtoꢀallowꢀevaporationꢀ
ofꢀ ammoniaꢀ andꢀ consequentꢀ depositionꢀ ofꢀ copperꢀ speciesꢀ onꢀ
silica.ꢀ Theꢀ evaporationꢀ processꢀ wasꢀ terminatedꢀ whenꢀ theꢀ pHꢀ
valueꢀ ofꢀ theꢀ suspensionꢀ decreasedꢀ toꢀ 7.ꢀ Theꢀ precipitatesꢀ ob‐
tainedꢀwereꢀfilteredꢀandꢀwashedꢀfiveꢀtimesꢀwithꢀdeionizedꢀwa‐
terꢀoneꢀtimeꢀwithꢀethanol.ꢀPriorꢀtoꢀcalcinationꢀinꢀairꢀforꢀ4ꢀh,ꢀtheꢀ
obtainedꢀ powderꢀ wasꢀ driedꢀ atꢀ 393ꢀ Kꢀ forꢀ 12ꢀ h.ꢀ Theꢀ obtainedꢀ
samplesꢀ wereꢀ pressed,ꢀ crushed,ꢀ andꢀ sievedꢀ throughꢀ 40–60ꢀ
2
H
2
mediatelyꢀreactedꢀwithꢀhydrogen.ꢀHydrogenꢀpulseꢀdosingꢀwasꢀ
repeatedꢀ untilꢀ theꢀ pulseꢀ areaꢀ didꢀ notꢀ change.ꢀ Theꢀ consumedꢀ
amountꢀofꢀhydrogenꢀwasꢀtheꢀvalueꢀobtainedꢀbyꢀsubtractingꢀtheꢀ
smallꢀ areaꢀ ofꢀ theꢀ firstꢀ fewꢀ pulsesꢀ fromꢀ theꢀ areaꢀ ofꢀ theꢀ otherꢀ
pulses.ꢀTheꢀspecificꢀsurfaceꢀareaꢀofꢀCuꢀwasꢀestimatedꢀfromꢀtheꢀ
19
totalꢀamountꢀofꢀN Oꢀconsumptionꢀwithꢀ1.46ꢀ×ꢀ10 ꢀcopperꢀat‐
2
omsꢀperꢀsquareꢀmeter.ꢀ ꢀ
Transmissionꢀelectronꢀmicroscopyꢀ(TEM)ꢀwasꢀperformedꢀonꢀ
aꢀ JEM‐2100ꢀ transmissionꢀ electronꢀ microscopeꢀ (JEOL,ꢀ Japan)ꢀ
withꢀanꢀoperatingꢀvoltageꢀofꢀ200ꢀkV.ꢀTheꢀsamplesꢀwereꢀultra‐
sonicallyꢀdispersedꢀinꢀethanolꢀatꢀroomꢀtemperatureꢀforꢀ15ꢀminꢀ
andꢀdepositedꢀonꢀcopperꢀgridsꢀcoatedꢀwithꢀamorphousꢀcarbonꢀ
films.ꢀ

486ꢀ
TongmeiꢀDingꢀetꢀal.ꢀ/ꢀChineseꢀJournalꢀofꢀCatalysisꢀ37ꢀ(2016)ꢀ484–493ꢀ
Tableꢀ1ꢀ
PhysicochemicalꢀpropertiesꢀofꢀtheꢀcalcinedꢀCu/SiO
2
ꢀcatalysts.ꢀ
Cuꢀloadingꢀaꢀ
A
V
ꢀ
d
ꢀ
d
c
d
d
Cuꢀdispersionꢀeꢀ
(%)ꢀ
S
CuOꢀeꢀ
2
BETꢀ
p
p
Cuꢀ ꢀ
Cuꢀ
ꢀ
Sampleꢀ
I
670/I800ꢀbꢀ
2
3
(
wt%)ꢀ
21.9ꢀ
21.8ꢀ
20.1ꢀ
22.2ꢀ
23.0ꢀ
(m /g)
273.4ꢀ
360.6ꢀ
223.2ꢀ
309.7ꢀ
260.1ꢀ
ꢀ
(cm /g)ꢀ
0.62ꢀ
1.14ꢀ
0.52ꢀ
0.76ꢀ
0.66ꢀ
(nm)ꢀ
ꢀ 7.8ꢀ
10.4ꢀ
ꢀ 6.8ꢀ
ꢀ 8.3ꢀ
ꢀ 9.0ꢀ
(nm)ꢀ
17.1ꢀ
13.8ꢀ
16.4ꢀ
17.7ꢀ
36.6ꢀ
(nm)ꢀ
15.0ꢀ
ꢀ 9.5ꢀ
13.9ꢀ
14.0ꢀ
32.1ꢀ
(m /g)ꢀ
21.2ꢀ
34.7ꢀ
18.6ꢀ
17.8ꢀ
ꢀ 8.8ꢀ
Cu/SiO
Cu/SiO
Cu/SiO
Cu/SiO
2
‐623ꢀ
2
‐723ꢀ
2
‐823ꢀ
2
‐923ꢀ
2
‐1023ꢀ
0.171ꢀ
0.258ꢀ
0.079ꢀ
0ꢀ
14.9ꢀ
24.5ꢀ
13.2ꢀ
12.6ꢀ
ꢀ 6.2ꢀ
Cu/SiO
0ꢀ
aꢀ
DeterminedꢀbyꢀICP‐AES.ꢀ
bꢀ
Byꢀintegrationꢀofꢀtheꢀfittedꢀpeaksꢀatꢀ670ꢀandꢀ800ꢀcm−1ꢀinꢀtheꢀFT‐IRꢀspectrum.ꢀ
cꢀ
CuꢀcrystalliteꢀsizeꢀcalculatedꢀbyꢀtheꢀScherrerꢀformulaꢀafterꢀreduction.ꢀ
dꢀ
CuꢀparticleꢀsizeꢀafterꢀreductionꢀmeasuredꢀbyꢀTEM.ꢀ
eꢀ
DeterminedꢀbyꢀN Oꢀchemisorption.ꢀ
2
ꢀ
X‐rayꢀ photoelectronꢀ spectroscopyꢀ (XPS)ꢀ andꢀ X‐rayꢀ Augerꢀ
electronꢀspectroscopyꢀ(XAES)ꢀwereꢀperformedꢀonꢀaꢀESCALABꢀ
50Xiꢀsystemꢀ(ThermoꢀFisher,ꢀUSA)ꢀoperatedꢀatꢀaꢀpassꢀenergyꢀ
ofꢀ100ꢀeVꢀandꢀequippedꢀwithꢀanꢀAlꢀK ꢀX‐rayꢀsourceꢀradiationꢀ
densedꢀ andꢀ analyzedꢀ byꢀ aꢀ gasꢀ chromatographꢀ (GC9800,ꢀ
Kechuangꢀ ChromatogramꢀInstrumentsꢀ Co.ꢀLtd.,ꢀShanghai,ꢀ Chi‐
na)ꢀfittedꢀwithꢀanꢀHT‐5ꢀcapillaryꢀcolumnꢀ(30ꢀmꢀ×ꢀ0.32ꢀmm)ꢀandꢀ
aꢀflameꢀionizationꢀdetector.ꢀ
2
α
sourceꢀ(Eꢀ=ꢀ1486.6ꢀeV).ꢀTheꢀcarbonaceousꢀCꢀ1sꢀlineꢀ(284.8ꢀeV)ꢀ
wasꢀ usedꢀ asꢀ theꢀ referenceꢀ toꢀ calibrateꢀ theꢀ bindingꢀ energiesꢀ
3.ꢀ ꢀ Resultsꢀandꢀdiscussionꢀ
(BEs).ꢀTheꢀcatalystsꢀwereꢀheatedꢀtoꢀ573ꢀKꢀinꢀpureꢀhydrogenꢀatꢀ
100ꢀ mL/minꢀ andꢀ reducedꢀ atꢀ thisꢀ temperatureꢀ forꢀ 4ꢀ h.ꢀ Afterꢀ
3.1.ꢀ ꢀ Texturalꢀpropertiesꢀofꢀtheꢀcatalystsꢀ
reduction,ꢀ theꢀ catalystsꢀ wereꢀ keptꢀ underꢀ nitrogenꢀ andꢀ trans‐
ferredꢀintoꢀtheꢀXPSꢀsampleꢀholderꢀusingꢀaꢀsealedꢀbottle.ꢀ
Theꢀ copperꢀ contentsꢀ inꢀ theꢀ Cu/SiO ꢀ catalystsꢀ wereꢀ deter‐
2
minedꢀbyꢀICP‐AESꢀ(Tableꢀ1).ꢀTheꢀbulkꢀweightꢀloadingsꢀofꢀcop‐
perꢀonꢀtheꢀsupportꢀwereꢀslightlyꢀlowerꢀthanꢀtheꢀnominalꢀvalueꢀ
2.3.ꢀ ꢀ Activityꢀtestsꢀ
(25ꢀwt%).ꢀDuringꢀtheꢀwashingꢀprocedure,ꢀtheꢀfiltrateꢀwasꢀdarkꢀ
DEMꢀ hydrogenationꢀ wasꢀ performedꢀ inꢀ aꢀ continuousꢀ flowꢀ
unitꢀequippedꢀwithꢀaꢀstainless‐steelꢀfixed‐bedꢀtubularꢀreactorꢀ
innerꢀ diameterꢀ 10ꢀ mm,ꢀ lengthꢀ 700ꢀ mm).ꢀ Typically,ꢀ 2.5ꢀ gꢀ ofꢀ
catalystꢀ (40–60ꢀ meshes)ꢀ wasꢀ loadedꢀ intoꢀ theꢀ tubularꢀ reactorꢀ
withꢀ aꢀ thermocoupleꢀ insertedꢀ intoꢀ theꢀ catalystꢀ bedꢀ forꢀ betterꢀ
controlꢀofꢀtheꢀactualꢀpretreatmentꢀandꢀreactionꢀtemperatures.ꢀ
blueꢀ duringꢀ theꢀ firstꢀ twoꢀ washings,ꢀ indicatingꢀ partialꢀ lossꢀ ofꢀ
copperꢀspecies.ꢀ
Theꢀ texturalꢀ properties,ꢀ includingꢀ theꢀ poreꢀ volume,ꢀ poreꢀ
diameter,ꢀandꢀBETꢀsurfaceꢀarea,ꢀhaveꢀaꢀprofoundꢀinfluenceꢀonꢀ
(
theꢀ catalyticꢀ behaviorꢀ ofꢀ catalysts.ꢀ Figureꢀ 1ꢀ showsꢀ typicalꢀ N
adsorption–desorptionꢀisothermsꢀandꢀtheꢀcorrespondingꢀporeꢀ
sizeꢀdistributionsꢀofꢀtheꢀcalcinedꢀCu/SiO ꢀcatalysts.ꢀAsꢀshownꢀinꢀ
2
ꢀ
Catalystꢀactivationꢀwasꢀperformedꢀatꢀ573ꢀKꢀforꢀ4ꢀhꢀinꢀflowingꢀH
100ꢀ mL/min).ꢀ Theꢀ temperatureꢀ wasꢀ thenꢀ decreasedꢀ toꢀ theꢀ
reactionꢀ temperatureꢀ ofꢀ 473ꢀ K,ꢀ andꢀ 10ꢀ wt%ꢀ DEMꢀ (purityꢀ >ꢀ
9%)ꢀinꢀethanolꢀwasꢀpumpedꢀintoꢀtheꢀreactorꢀbyꢀanꢀadvectionꢀ
pumpꢀalongꢀwithꢀH ꢀatꢀaꢀH /DEMꢀmolarꢀratioꢀofꢀ440ꢀandꢀaꢀsys‐
temꢀ pressureꢀ ofꢀ 2.0ꢀ MPa.ꢀ Theꢀ liquidꢀ hourlyꢀ spaceꢀ velocityꢀ
2
ꢀ
2
(
Fig.ꢀ1(a),ꢀallꢀofꢀtheꢀcatalystsꢀshowꢀaꢀtypeꢀIVꢀLangmuirꢀadsorp‐
tionꢀisothermꢀwithꢀanꢀH3‐typeꢀloop,ꢀcorrespondingꢀtoꢀaꢀtypicalꢀ
large‐poreꢀmesoporousꢀmaterialꢀ[34].ꢀCapillaryꢀcondensationꢀofꢀ
nitrogenꢀ occurredꢀ insideꢀ theꢀ mesopores,ꢀ suggestingꢀ aꢀ typicalꢀ
mesoporousꢀstructureꢀwithꢀuniformꢀporeꢀdiametersꢀ[35].ꢀTheꢀ
9
2
2
−1
(
LHSV)ꢀ ofꢀ DEMꢀ wasꢀ setꢀ toꢀ 1.80ꢀ h .ꢀ Theꢀ productsꢀ wereꢀ con‐
Cu/SiO ‐723ꢀcatalystꢀshowedꢀtheꢀmostꢀuniformꢀporeꢀsizeꢀdis‐
2
(b)
(a)
(5)
(5)
(
4)
3)
(4)
(
(3)
(2)
(2)
(1)
(1)
0.2
0.4
0.6
0.8
1.0
0
5
10 15 20 25 30 35 40 45 50
Pore diameter (nm)
p/p0
Fig.ꢀ1.ꢀ(a)ꢀN
2
ꢀadsorption‐desorptionꢀisothermsꢀandꢀ(b)ꢀBJHꢀporeꢀsizeꢀdistributionsꢀofꢀtheꢀcalcinedꢀcatalysts:ꢀ(1)ꢀCu/SiO
‐923;ꢀ(5)ꢀCu/SiO ‐1023.ꢀ
2
‐623;ꢀ(2)ꢀCu/SiO ‐723;ꢀ(3)ꢀ
2
2
Cu/SiO ‐823;ꢀ(4)ꢀCu/SiO
2
2

ꢀ
TongmeiꢀDingꢀetꢀal.ꢀ/ꢀChineseꢀJournalꢀofꢀCatalysisꢀ37ꢀ(2016)ꢀ484–493ꢀ
487ꢀ
tributionꢀforꢀtheꢀrelativeꢀlongꢀsaturatedꢀadsorptionꢀplatform.ꢀAsꢀ
shownꢀinꢀFig.ꢀ1(b),ꢀporesꢀwithꢀdiametersꢀofꢀ~3.3ꢀandꢀ~17ꢀnmꢀ
areꢀ theꢀ mainꢀ contributorsꢀ toꢀ theꢀ totalꢀ poreꢀ volumeꢀ ofꢀ theꢀ
servedꢀ [36],ꢀ indicatingꢀ aggregationꢀ ofꢀ Cuꢀ nanoparticles.ꢀ Theꢀ
CuOꢀ crystalliteꢀ sizeꢀ basedꢀ onꢀ theꢀ Scherrerꢀ equationꢀ isꢀ aboutꢀ
12.7ꢀ nm.ꢀ Additionally,ꢀ extremelyꢀ weakꢀ andꢀ broadꢀ diffractionꢀ
peaksꢀatꢀ31°,ꢀ34.8°,ꢀ57.2°,ꢀandꢀ63.3°ꢀareꢀassignedꢀtoꢀtheꢀcopperꢀ
Cu/SiO
17ꢀnmꢀinꢀsizeꢀforꢀCu/SiO
cinationꢀtemperatureꢀofꢀ823ꢀK,ꢀindicatingꢀaggregationꢀofꢀcopperꢀ
species.ꢀTheꢀsmallerꢀporeꢀsizeꢀinꢀCu/SiO ‐623ꢀthanꢀCu/SiO ‐723ꢀ
2
‐723ꢀ catalyst.ꢀ Theꢀ sizeꢀ ofꢀ theꢀ largerꢀ poresꢀ (i.e.,ꢀ thoseꢀ
~
2
‐723)ꢀdecreasedꢀtoꢀ7.2ꢀnmꢀforꢀaꢀcal‐
phyllosilicateꢀ (Cu
2
Si
2
O
5
(OH)
2
)ꢀ phaseꢀ overꢀ theꢀ Cu/SiO ‐623ꢀ
2
catalystꢀ[28].ꢀTheꢀresultsꢀshowꢀthatꢀhighꢀcalcinationꢀtempera‐
tureꢀ facilitatesꢀ formationꢀ ofꢀ CuOꢀ whileꢀ copperꢀ phyllosilicateꢀ
formsꢀatꢀlowꢀcalcinationꢀtemperature.ꢀ
2
2
indicatesꢀ thatꢀ lowꢀ calcinationꢀ temperatureꢀ isꢀ detrimentalꢀ forꢀ
theꢀformationꢀofꢀlarge‐volumeꢀpores.ꢀ
XRDꢀpatternsꢀofꢀtheꢀreducedꢀCu/SiO ꢀsamplesꢀareꢀshownꢀinꢀ
2
TheꢀBETꢀsurfaceꢀareas,ꢀporeꢀvolumes,ꢀandꢀaverageꢀporeꢀdi‐
ametersꢀofꢀsamplesꢀareꢀsummarizedꢀinꢀTableꢀ1.ꢀTheꢀBETꢀsur‐
Fig.ꢀ 2(b).ꢀ Theꢀ diffractionꢀ peaksꢀ ofꢀ copperꢀ oxideꢀ andꢀ copperꢀ
phyllosilicateꢀ observedꢀ inꢀ theꢀ calcinedꢀ samplesꢀ disappeared.ꢀ
Diffractionꢀpeaksꢀatꢀ43.2°ꢀandꢀ50.3°ꢀascribedꢀtoꢀtheꢀCuꢀphaseꢀ
2
faceꢀ areaꢀ increasedꢀ fromꢀ 273.4ꢀ toꢀ 360.6ꢀ m /gꢀ andꢀ theꢀ poreꢀ
3
volumeꢀincreasedꢀfromꢀ0.62ꢀtoꢀ1.14ꢀcm /gꢀwhenꢀtheꢀcalcinationꢀ
andꢀaꢀdiffractionꢀpeakꢀatꢀ36.5°ꢀattributedꢀtoꢀtheꢀCu
2
Oꢀphaseꢀareꢀ
2+
0
temperatureꢀ wasꢀ increasedꢀ fromꢀ 623ꢀ toꢀ 723ꢀ K,ꢀ andꢀ thenꢀ de‐
creasedꢀ withꢀ furtherꢀ increaseꢀ ofꢀ theꢀ calcinationꢀ temperature.ꢀ
However,ꢀthereꢀwasꢀaꢀnonmonotonicꢀchangeꢀwhenꢀtheꢀcalcina‐
tionꢀ temperatureꢀ increasedꢀ fromꢀ 823ꢀ toꢀ 1023ꢀ K.ꢀ Hence,ꢀ weꢀ
deducedꢀthatꢀtheꢀstructureꢀandꢀspeciesꢀofꢀtheꢀcatalystsꢀmark‐
edlyꢀchangedꢀwithꢀcalcinationꢀtemperature.ꢀ
observedꢀ[11],ꢀindicatingꢀthatꢀCu ꢀspeciesꢀareꢀreducedꢀtoꢀCu ꢀ
+
andꢀCu ꢀinꢀtheꢀreducedꢀcatalysts.ꢀTheꢀintensitiesꢀofꢀtheꢀCuꢀdif‐
fractionꢀpeaksꢀareꢀtheꢀhighestꢀatꢀaꢀcalcinationꢀtemperatureꢀofꢀ
+
923ꢀKꢀandꢀtheꢀintensityꢀofꢀtheꢀCu ꢀdiffractionꢀpeakꢀisꢀtheꢀhighestꢀ
forꢀCu/SiO ‐723.ꢀTheꢀcalcinationꢀtemperatureꢀaffectsꢀtheꢀratioꢀ
2
0
+
ofꢀ Cu /Cu ,ꢀ whichꢀ directlyꢀ affectsꢀ theꢀ catalyticꢀ activity.ꢀ Asꢀ
shownꢀinꢀTableꢀ1,ꢀtheꢀCuꢀparticleꢀsizeꢀcalculatedꢀbyꢀtheꢀScherrerꢀ
equationꢀdecreasesꢀfromꢀ17.1ꢀtoꢀ13.8ꢀnmꢀwhenꢀincreasingꢀtheꢀ
calcinationꢀtemperatureꢀfromꢀ623ꢀtoꢀ723ꢀK,ꢀandꢀthenꢀincreasesꢀ
withꢀfurtherꢀincreasingꢀcalcinationꢀtemperature,ꢀindicatingꢀthatꢀ
Metallicꢀcopperꢀdispersionꢀandꢀtheꢀcupreousꢀsurfaceꢀareasꢀ
ofꢀtheꢀCu/SiO
2
ꢀ catalystsꢀ wereꢀ determinedꢀ byꢀ N Oꢀ chemisorp‐
2
tionsꢀ (Tableꢀ 1).ꢀ Copperꢀ dispersionꢀ andꢀ theꢀ cupreousꢀ surfaceꢀ
areaꢀ increasedꢀ withꢀ increasingꢀ calcinationꢀ temperatureꢀ fromꢀ
623ꢀtoꢀ723ꢀK,ꢀandꢀthenꢀdecreasedꢀwithꢀincreasingꢀcalcinationꢀ
2
theꢀCuꢀparticleꢀsizeꢀisꢀtheꢀsmallestꢀinꢀtheꢀCu/SiO ‐723ꢀcatalystꢀ
temperatureꢀ fromꢀ 823ꢀ toꢀ 1023ꢀ K.ꢀ Cu/SiO
highestꢀdispersionꢀ(24.5ꢀ%)ꢀandꢀlargestꢀCu ꢀsurfaceꢀareaꢀ(34.7ꢀ
2
‐723ꢀ showedꢀ theꢀ
afterꢀreduction.ꢀ
0
2
m /g).ꢀ Cu/SiO
2
‐1023ꢀ showedꢀ significantlyꢀ lowerꢀ copperꢀ dis‐
3.3.ꢀ ꢀ FT‐IRꢀspectroscopyꢀ
persionꢀ andꢀ cupreousꢀ surfaceꢀ areaꢀ thanꢀ theꢀ otherꢀ catalysts,ꢀ
whichꢀisꢀmostꢀprobablyꢀbecauseꢀofꢀcopperꢀparticleꢀaggregationꢀ
atꢀhighꢀcalcinationꢀtemperature.ꢀ ꢀ
Interestingly,ꢀ theꢀ colorꢀ ofꢀ theꢀ calcinedꢀ catalystsꢀ changedꢀ
fromꢀblueꢀtoꢀdarkꢀblueꢀwithꢀincreasingꢀcalcinationꢀtemperature,ꢀ
indicatingꢀ theꢀ appearanceꢀ ofꢀ atꢀ leastꢀ twoꢀ copperꢀ species.ꢀ Forꢀ
3.2.ꢀ ꢀ Wide‐angleꢀXRDꢀ
Cu/SiO ‐1023,ꢀtheꢀsampleꢀwasꢀnearlyꢀblack,ꢀwhichꢀisꢀattributedꢀ
2
toꢀtheꢀpresenceꢀofꢀCuO.ꢀToꢀgainꢀfurtherꢀinsightꢀintoꢀtheꢀstruc‐
ture,ꢀFT‐IRꢀspectraꢀofꢀtheꢀcalcinedꢀsamplesꢀwereꢀrecorded,ꢀasꢀ
XRDꢀpatternsꢀofꢀCu/SiO
peraturesꢀ areꢀ shownꢀ inꢀ Fig.ꢀ 2(a).ꢀ Forꢀ catalystsꢀ calcinedꢀ fromꢀ
23ꢀtoꢀ923ꢀK,ꢀnoꢀobviousꢀdiffractionꢀpeaksꢀareꢀobservedꢀexceptꢀ
forꢀaꢀbroadꢀdiffractionꢀpeakꢀatꢀ22°ꢀfromꢀamorphousꢀsilica,ꢀindi‐
catingꢀhomogeneousꢀdispersionꢀofꢀcopperꢀspeciesꢀonꢀtheꢀsup‐
port.ꢀAtꢀaꢀcalcinationꢀtemperatureꢀofꢀ1023ꢀK,ꢀdiffractionꢀpeaksꢀ
atꢀ 35.3°ꢀ andꢀ 38.7°ꢀ assignedꢀ toꢀ CuOꢀ (JCPDSꢀ 05‐0661)ꢀ areꢀ ob‐
2
ꢀcatalystsꢀcalcinedꢀatꢀdifferentꢀtem‐
−1
shownꢀ inꢀ Fig.ꢀ 3.ꢀ Theꢀ bandꢀ atꢀ 1637ꢀ cm ꢀ correspondsꢀ toꢀ theꢀ
bendingꢀmodeꢀofꢀOHꢀgroupsꢀofꢀabsorbedꢀwaterꢀ[27,37]ꢀandꢀtheꢀ
7
−1
absorptionꢀ bandsꢀ atꢀ approximatelyꢀ 1119,ꢀ 800,ꢀ andꢀ 472ꢀ cm ꢀ
areꢀ assignedꢀ toꢀ differentꢀ vibrationꢀ modesꢀ ofꢀ Si–Oꢀ bondsꢀ ofꢀ
amorphousꢀsilicaꢀ[38].ꢀForꢀtheꢀCu/SiO
2
‐623,ꢀCu/SiO ‐723,ꢀandꢀ
2
−
1
Cu/SiO ‐823ꢀcatalysts,ꢀtheꢀsingleꢀδOHꢀbandꢀatꢀ672ꢀcm ꢀandꢀνSiO
2
ꢀ
Cu
Cu
SiO
(b)
(a)
CuO
SiO
Chrysocolla
2
O
2
2
(
5)
4)
3)
2)
(1)
80
(
5)
(
(
4)
(
(
3)
2)
(
(
(
1)
10
20
30
40
2 /( )
50
60
70
10
20
30
40
 /( )
50
60
70
80
o
o
2
Fig.ꢀ2.ꢀXRDꢀpatternsꢀofꢀcatalystsꢀafterꢀ(a)ꢀcalcinationꢀandꢀ(b)ꢀreduction:ꢀ(1)ꢀCu/SiO
Cu/SiO ‐1023.ꢀ
2
‐623;ꢀ(2)ꢀCu/SiO
2
‐723;ꢀ(3)ꢀCu/SiO
2
‐823;ꢀ(4)ꢀCu/SiO ‐923;ꢀ(5)ꢀ
2
2

488ꢀ
TongmeiꢀDingꢀetꢀal.ꢀ/ꢀChineseꢀJournalꢀofꢀCatalysisꢀ37ꢀ(2016)ꢀ484–493ꢀ
theꢀcalcinationꢀtemperatureꢀwasꢀincreasedꢀfromꢀ723ꢀtoꢀ823ꢀK,ꢀ
andꢀwasꢀzeroꢀforꢀcalcinationꢀtemperaturesꢀ≥ꢀ923ꢀK.ꢀ
1637
1119 938 800
038
472
(
5)
4)
1
3.4.ꢀ ꢀ TEMꢀresultsꢀ
(
(
3)
2)
672
Figureꢀ4ꢀshowsꢀTEMꢀimagesꢀofꢀtheꢀsupport,ꢀcalcinedꢀcata‐
(
lysts,ꢀ andꢀ reducedꢀ catalysts.ꢀ Figureꢀ 4(a)ꢀ showsꢀ theꢀ orderlyꢀ
morphologyꢀofꢀtheꢀsupport.ꢀCopperꢀspeciesꢀappearꢀasꢀsphericalꢀ
particlesꢀoverꢀtheꢀotherꢀsamplesꢀ(Fig.ꢀ4(b)–(e)).ꢀCopperꢀspeciesꢀ
(1)
inꢀ theꢀ Cu/SiO
dispersedꢀ overꢀ theꢀ supportꢀ andꢀ theꢀ particleꢀ sizesꢀ areꢀ inꢀ theꢀ
rangeꢀ2–6ꢀnm.ꢀForꢀtheꢀCu/SiO ‐823ꢀandꢀCu/SiO ‐923ꢀcatalysts,ꢀ
aggregationꢀ ofꢀ aꢀ fewꢀ copperꢀ speciesꢀ isꢀ observed.ꢀ Forꢀ theꢀ
Cu/SiO ‐1023ꢀcatalyst,ꢀcopperꢀspeciesꢀformꢀbulkꢀcrystals,ꢀindi‐
2
‐623ꢀ andꢀ Cu/SiO
2
‐723ꢀ catalystsꢀ areꢀ uniformlyꢀ
2
2
2
000 1800 1600 1400 1200 1000 800 600 400
1
2
Wavenumber (cm )
catingꢀthatꢀlargeꢀcopperꢀparticlesꢀ(>ꢀ300ꢀnm)ꢀformꢀatꢀhighꢀcal‐
cinationꢀ temperature.ꢀ Theꢀ resultsꢀ areꢀ inꢀ agreementꢀ withꢀ theꢀ
Fig.ꢀ 3.ꢀ FT‐IRꢀ spectraꢀ ofꢀ theꢀ differentꢀ catalysts:ꢀ (1)ꢀ Cu/SiO
2
‐623;ꢀ (2)ꢀ
Cu/SiO ‐723;ꢀ(3)ꢀCu/SiO ‐823;ꢀ(4)ꢀCu/SiO ‐923;ꢀ(5)ꢀCu/SiO ‐1023.ꢀ
2
2
2
2
N
2
Oꢀ chemisorptionꢀ andꢀ XRDꢀ analyses.ꢀ Forꢀ theꢀ Cu/SiO ‐623ꢀ
2
catalyst,ꢀtheꢀtypicalꢀfilandrousꢀmorphologyꢀofꢀcopperꢀphyllosil‐
icateꢀ [27]ꢀ isꢀ observed,ꢀ whichꢀ isꢀ moreꢀ apparentꢀ inꢀ theꢀ
−
1
shoulderꢀ peakꢀ atꢀ 1038ꢀ cm ꢀ indicateꢀ theꢀ presenceꢀ ofꢀ copperꢀ
phyllosilicate.ꢀFormationꢀofꢀcopperꢀphyllosilicateꢀindicatesꢀthatꢀ
copperꢀ couldꢀ insertꢀ intoꢀ theꢀ frameworkꢀ ofꢀ theꢀ silicaꢀ supportꢀ
andꢀ linkꢀ withꢀ theꢀ supportꢀ byꢀ chemicalꢀ bonds,ꢀ soꢀ aꢀ met‐
al–supportꢀinteractionꢀexistsꢀbetweenꢀcopperꢀandꢀtheꢀsupport.ꢀ
Cu/SiO
2
‐723ꢀ sample.ꢀ Itꢀ isꢀ notꢀ presentꢀ inꢀ Cu/SiO
‐923.ꢀ Forꢀ theꢀ reducedꢀ catalystsꢀ (Fig.ꢀ 4(g)–(i)),ꢀ copperꢀ
‐723.ꢀ Theꢀ Cuꢀ particleꢀ
sizesꢀmeasuredꢀbyꢀTEMꢀareꢀshownꢀinꢀTableꢀ1.ꢀTheꢀcopperꢀpar‐
ticlesꢀ areꢀ theꢀ smallestꢀ inꢀ Cu/SiO ‐723,ꢀ whichꢀ possessesꢀ theꢀ
2
‐1023ꢀ andꢀ
Cu/SiO
2
particlesꢀ aggregate,ꢀ exceptꢀ forꢀ Cu/SiO
2
AccordingꢀtoꢀtheꢀXRDꢀandꢀN
2
Oꢀanalyses,ꢀweꢀdeducedꢀthatꢀcop‐
2
perꢀdispersionꢀandꢀtheꢀactiveꢀsitesꢀcouldꢀbeꢀchangedꢀbyꢀsettingꢀ
theꢀcalcinationꢀtemperatureꢀinꢀaꢀdifferentꢀrange.ꢀ
highestꢀthermalꢀstability.ꢀTheꢀresultsꢀwereꢀinꢀgoodꢀagreementꢀ
withꢀtheꢀXRDꢀanalysis.ꢀ
Theꢀrelativeꢀamountꢀofꢀcopperꢀphyllosilicateꢀwasꢀcalculatedꢀ
byꢀconsideringꢀtheꢀintegratedꢀintensityꢀofꢀtheꢀδOHꢀbandꢀatꢀ670ꢀ
cm ꢀnormalizedꢀtoꢀtheꢀintegratedꢀintensityꢀofꢀtheꢀ symmetricꢀ
3.5.ꢀ ꢀ Redoxꢀpropertiesꢀofꢀtheꢀcatalystsꢀ
−1
−1
2
H ‐TPRꢀisꢀaꢀveryꢀusefulꢀtechniqueꢀtoꢀinvestigateꢀtheꢀredoxꢀ
ν
SiOꢀbandꢀofꢀamorphousꢀsilicaꢀatꢀ800ꢀcm ,ꢀwhichꢀisꢀreferredꢀtoꢀ
I670/I800ꢀ [39].ꢀ Fromꢀ integrationꢀ fittingꢀ Tableꢀ 1,ꢀ theꢀ relativeꢀ
propertiesꢀofꢀcatalysts.ꢀFigureꢀ5ꢀshowsꢀTPRꢀprofilesꢀofꢀtheꢀcal‐
amountꢀofꢀcopperꢀphyllosilicateꢀincreasedꢀwhenꢀtheꢀcalcinationꢀ
temperatureꢀwasꢀincreasedꢀfromꢀ623ꢀtoꢀ723ꢀK,ꢀdecreasedꢀwhenꢀ
cinedꢀCu/SiO
2
ꢀcatalysts.ꢀForꢀtheꢀcatalystꢀcalcinedꢀatꢀ623ꢀK,ꢀtheꢀ
spectraꢀ exhibitsꢀ aꢀ narrowꢀ andꢀ nearlyꢀ symmetricalꢀ reductionꢀ
(a)
(d)
(g)
(b)
(e)
(h)
(c)
(f)
(i)
Fig.ꢀ4.ꢀTEMꢀimagesꢀofꢀtheꢀsupport,ꢀandꢀcalcinedꢀandꢀreducedꢀCu/SiO
Cu/SiO ‐923;ꢀ(f)ꢀCu/SiO ‐1023;ꢀ(g)ꢀCu/SiO
2
ꢀcatalysts:ꢀ(a)ꢀsupport;ꢀ(b)ꢀCu/SiO
2
‐623;ꢀ(c)ꢀCu/SiO
‐1023ꢀafterꢀreduction.ꢀ
2
‐723;ꢀ(d)ꢀCu/SiO ‐823;ꢀ(e)ꢀ
2
2
2
2
‐623ꢀafterꢀreduction;ꢀ(h)ꢀCu/SiO
2
‐723ꢀafterꢀreduction;ꢀ(i)ꢀCu/SiO
2

ꢀ
TongmeiꢀDingꢀetꢀal.ꢀ/ꢀChineseꢀJournalꢀofꢀCatalysisꢀ37ꢀ(2016)ꢀ484–493ꢀ
489ꢀ
dispersedꢀ copperꢀ oxide.ꢀ Combiningꢀ withꢀ theꢀ FT‐IRꢀ andꢀ TEMꢀ
analyses,ꢀ theꢀ strongꢀ andꢀ symmetricalꢀ reductionꢀ peaksꢀ forꢀ
454
549
Cu/SiO
2
‐623ꢀandꢀCu/SiO
2
‐723ꢀcanꢀbeꢀattributedꢀtoꢀtheꢀreduc‐
(
5)
4)
488
tionꢀofꢀcopperꢀphyllosilicateꢀtoꢀCu ꢀoverlappedꢀwithꢀreductionꢀ
ofꢀ well‐dispersedꢀ CuOꢀ toꢀ Cu .ꢀ Theꢀ reductionꢀ peakꢀ ofꢀ
+
0
(
well‐dispersedꢀCuOꢀisꢀpresentꢀinꢀtheꢀspectrumꢀofꢀCu/SiO
andꢀtheꢀreductionꢀpeakꢀofꢀpoorlyꢀdispersedꢀCuOꢀexistsꢀinꢀtheꢀ
spectrumꢀofꢀCu/SiO ‐1023.ꢀHowever,ꢀtheꢀshoulderꢀpeakꢀinꢀtheꢀ
TPRꢀprofileꢀofꢀCu/SiO ‐823ꢀmayꢀindicateꢀtheꢀpresenceꢀofꢀpoorlyꢀ
dispersedꢀcopperꢀphyllosilicate.ꢀ
2
‐923ꢀ
478
(3)
(2)
(1)
2
2
3.6.ꢀ ꢀ Surfaceꢀchemicalꢀstatesꢀ
464
350
400
450
500
550
600
650
700
Theꢀ surfaceꢀ compositionꢀ andꢀ oxidationꢀ statesꢀ ofꢀ theꢀ cata‐
Temperature (K)
lystsꢀ wereꢀ investigatedꢀ byꢀ XPS.ꢀ XPSꢀ andꢀ XAESꢀ spectraꢀ ofꢀ theꢀ
reducedꢀCu/SiO ꢀcatalystsꢀareꢀshownꢀinꢀFig.ꢀ6.ꢀInꢀFig.ꢀ6(a),ꢀtheꢀ
twoꢀintensiveꢀphotoelectronꢀpeaksꢀlocatedꢀatꢀ932.8ꢀandꢀ952.6ꢀ
Fig.ꢀ 5.ꢀ TPRꢀ profilesꢀ ofꢀ theꢀ Cu/SiO
2
ꢀ catalysts:ꢀ (1)ꢀ Cu/SiO ‐623;ꢀ (2)ꢀ
2
2
Cu/SiO ‐723;ꢀ(3)ꢀCu/SiO ‐823;ꢀ(4)ꢀCu/SiO ‐923;ꢀ(5)ꢀCu/SiO ‐1023.ꢀ
2
2
2
2
eVꢀareꢀascribedꢀtoꢀtheꢀCuꢀ2p2/3ꢀandꢀCuꢀ2p1/2ꢀbindingꢀenergiesꢀofꢀ
peakꢀatꢀca.ꢀ464ꢀK,ꢀindicatingꢀgoodꢀdispersionꢀofꢀcopperꢀspeciesꢀ
withꢀsmallꢀparticleꢀsizes.ꢀForꢀtheꢀCu/SiO ‐823ꢀcatalyst,ꢀtheꢀmainꢀ
Cu
+
ꢀorꢀCu ꢀspecies.ꢀForꢀallꢀofꢀtheꢀcatalysts,ꢀthereꢀareꢀnoꢀsatelliteꢀ
0
peaksꢀatꢀ944–945ꢀeVꢀ[42]ꢀrelatedꢀtoꢀCu2+,ꢀsuggestingꢀthatꢀCu2+
2
ꢀ
reductionꢀ peakꢀ shiftsꢀ toꢀ lowerꢀ temperatureꢀ andꢀ thereꢀ isꢀ aꢀ
shoulderꢀpeakꢀatꢀca.ꢀ478ꢀK,ꢀindicatingꢀthatꢀatꢀleastꢀtwoꢀdifferentꢀ
Cuꢀ speciesꢀ areꢀ present.ꢀ Theꢀ reductionꢀ peakꢀ shiftedꢀ toꢀ highꢀ
temperatureꢀ atꢀ aꢀ calcinationꢀ temperatureꢀ ofꢀ 923ꢀ Kꢀ andꢀ itꢀ isꢀ
symmetrical,ꢀwhichꢀcanꢀbeꢀascribedꢀtoꢀwell‐dispersedꢀCuO.ꢀForꢀ
speciesꢀwereꢀreducedꢀtoꢀaꢀlowerꢀvalenceꢀstateꢀofꢀ+1ꢀorꢀ0.ꢀTheꢀ
amountsꢀ ofꢀ Cu ꢀ andꢀ Cu ꢀ speciesꢀ canꢀ beꢀ determinedꢀ fromꢀ theꢀ
XAESꢀ spectra.ꢀ Asꢀ shownꢀ inꢀ Fig.ꢀ 6(b),ꢀ asymmetricꢀ andꢀ broadꢀ
peaksꢀareꢀobservedꢀandꢀcanꢀbeꢀdeconvolutedꢀintoꢀtwoꢀsymmet‐
ricalꢀpeaksꢀcenteredꢀatꢀaroundꢀ914ꢀandꢀ916ꢀeV,ꢀcorrespondingꢀ
0
+
Cu/SiO
isꢀaꢀshoulderꢀpeakꢀatꢀ503ꢀK.ꢀThereꢀisꢀanꢀadditionalꢀreductionꢀ
peakꢀatꢀca.ꢀ549ꢀKꢀforꢀCu/SiO ‐723ꢀandꢀCu/SiO ‐823.ꢀThisꢀpeakꢀ
2
‐1023,ꢀtheꢀmainꢀreductionꢀpeakꢀisꢀatꢀca.ꢀ488ꢀKꢀandꢀthereꢀ
toꢀCu
+
ꢀandꢀCu
0
ꢀspecies.ꢀTheseꢀresultsꢀindicateꢀthatꢀbothꢀCu ꢀandꢀ
+
0
Cu ꢀcoexistꢀonꢀtheꢀsurfaceꢀsilica,ꢀwhichꢀisꢀinꢀagreementꢀwithꢀtheꢀ
2
2
XRDꢀandꢀTPRꢀanalyses.ꢀ
canꢀbeꢀattributedꢀtoꢀtheꢀreductionꢀofꢀbulkꢀ CuOꢀ[40].ꢀTheꢀlowꢀ
reductionꢀ temperatureꢀ stronglyꢀ suggestsꢀ thatꢀ theꢀ ammoniaꢀ
evaporationꢀmethodꢀcanꢀbeꢀusedꢀtoꢀfinelyꢀdisperseꢀcupreousꢀonꢀ
TheꢀmodifiedꢀAugerꢀparameterꢀα′,ꢀwhichꢀrepresentsꢀtheꢀsumꢀ
ofꢀ theꢀ kineticꢀ energyꢀ ofꢀ theꢀ Cuꢀ LMMꢀ Augerꢀ electronꢀ andꢀ theꢀ
bindingꢀenergyꢀofꢀtheꢀCuꢀ2p2/3ꢀphotoelectron,ꢀwasꢀusedꢀtoꢀdis‐
2
silicaꢀforꢀCu/SiO ꢀcatalysts,ꢀwhichꢀcanꢀbeꢀeasilyꢀreducedꢀtoꢀpro‐
tinguishꢀCu
+
ꢀandꢀCu
0
ꢀspecies.ꢀGenerally,ꢀα′ꢀ=ꢀ~1851.0ꢀeVꢀforꢀCu
0
ꢀ
videꢀmoreꢀactiveꢀsites.ꢀ
andꢀα′ꢀ=ꢀ~1849.0ꢀeVꢀforꢀCu
+
.ꢀItꢀhasꢀbeenꢀreportedꢀthatꢀwhenꢀ
ItꢀhasꢀbeenꢀreportedꢀthatꢀtheꢀCu/SiO
ductionꢀpeakꢀatꢀ463ꢀKꢀ[41].ꢀZhangꢀetꢀal.ꢀ[26]ꢀreportedꢀthatꢀtheꢀ
2
ꢀcatalystꢀshowsꢀaꢀre‐
copperꢀ(+2,ꢀ+1,ꢀandꢀ0ꢀvalenceꢀstates)ꢀisꢀinꢀaꢀhighlyꢀdispersedꢀ
stateꢀandꢀinꢀintimateꢀcontactꢀwithꢀasupport,ꢀα′ꢀcanꢀbeꢀ2–3ꢀeVꢀ
lowerꢀthanꢀtheꢀbulkꢀvalueꢀ[43].ꢀAsꢀlistedꢀinꢀTableꢀ2,ꢀcopperꢀspe‐
2
reductionꢀofꢀCu/SiO ꢀcatalystꢀsamplesꢀfromꢀ482ꢀtoꢀ512ꢀKꢀcon‐
+
0
sistedꢀofꢀreductionꢀofꢀcopperꢀphyllosilicateꢀtoꢀCu ꢀandꢀwell‐
ꢀ
dis‐
ciesꢀwithꢀα′ꢀ=ꢀ~1849ꢀeVꢀareꢀascribedꢀtoꢀCu ꢀandꢀthoseꢀwithꢀα′ꢀ=ꢀ
0
+
+
0
persedꢀCuOꢀdirectlyꢀtoꢀCu .ꢀMaꢀetꢀal.ꢀ[20]ꢀreportedꢀthatꢀonlyꢀoneꢀ
strongꢀreductionꢀpeakꢀatꢀca.ꢀ480ꢀKꢀcanꢀbeꢀattributedꢀtoꢀreduc‐
~1847ꢀeVꢀareꢀascribedꢀtoꢀCu .ꢀTheꢀlowerꢀvaluesꢀforꢀCu ꢀandꢀCu ꢀ
thanꢀ theꢀ bulkꢀ valuesꢀ areꢀ attributedꢀ toꢀ theꢀ strongꢀ interactionꢀ
tionꢀ ofꢀ Cu–O–Siꢀ overlappedꢀ withꢀ theꢀ reductionꢀ peakꢀ ofꢀ well‐
ꢀ
betweenꢀcopperꢀspeciesꢀandꢀtheꢀsupport.ꢀTheꢀCu
+
/(Cu
+
ꢀ+ꢀCu )ꢀ
0
932.8
(b)
(a)
952.6
(5)
(
5)
4)
(
4)
3)
(
(
(3)
(2)
(1)
(
2)
1)
(
9
65 960 955 950 945 940 935 930 925
910
912
914
Kinetic energy (eV)
ꢀ catalysts:ꢀ (1)ꢀ Cu/SiO ‐623;ꢀ (2)ꢀ Cu/SiO
916
918
920
Binding energy (eV)
Fig.ꢀ 6.ꢀ (a)ꢀ Cuꢀ 2pꢀ XPSꢀ andꢀ (b)ꢀ Cuꢀ LMMꢀ augerꢀ spectraꢀ ofꢀ theꢀ reducedꢀ Cu/SiO
Cu/SiO ‐923;ꢀ(5)ꢀCu/SiO ‐1023.ꢀ
2
2
2
‐723;ꢀ (3)ꢀ Cu/SiO ‐823;ꢀ (4)ꢀ
2
2
2

4
90ꢀ
TongmeiꢀDingꢀetꢀal.ꢀ/ꢀChineseꢀJournalꢀofꢀCatalysisꢀ37ꢀ(2016)ꢀ484–493ꢀ
Tableꢀ3ꢀ
Tableꢀ2ꢀ
SurfaceꢀCuꢀcomponentsꢀofꢀtheꢀreducedꢀCu/SiO
LMMꢀdeconvolution.ꢀ
2
ꢀcatalystsꢀbasedꢀonꢀCuꢀ
CatalyticꢀperformanceꢀofꢀtheꢀCu/SiO
2
ꢀcatalysts.ꢀ
DEMꢀ ꢀ
Selectivityꢀ(%)ꢀ
Catalystꢀ
aꢀ
bꢀ
BEꢀofꢀCuꢀ XꢀCu+ꢀdꢀ
KEꢀ (eV)ꢀ
Cu+ꢀ Cu0ꢀ
ꢀ
ꢀ
APꢀ (eV)ꢀ
Cu+ꢀ
conversionꢀ(%) 1,3‐PDOꢀ 3‐HPEꢀ
NPAꢀ
31.6ꢀ
ꢀ 8.9ꢀ
18.7ꢀ
14.6ꢀ
34.9ꢀ
EPꢀ
Catalystꢀ
Cu0ꢀ 2p3/2ꢀ (eV) (%)
cꢀ
Cu/SiO
Cu/SiO
Cu/SiO
Cu/SiO
Cu/SiO
2
‐623ꢀ
2
‐723ꢀ
2
‐823ꢀ
2
‐923ꢀ
2
‐1023
91.9ꢀ
90.7ꢀ
95.2ꢀ
96.5ꢀ
90.3ꢀ
29.3ꢀ
32.3ꢀ
27.3ꢀ
18.0ꢀ
ꢀ 8.0ꢀ
10.6ꢀ
38.9ꢀ
35.6ꢀ
41.6ꢀ
19.0ꢀ
22.4ꢀ
13.9ꢀ
18.2ꢀ
19.2ꢀ
31.4ꢀ
Cu/SiO
Cu/SiO
Cu/SiO
Cu/SiO
2
2
2
2
2
‐623ꢀ 913.6ꢀ 916.4ꢀ ꢀ 1846.3ꢀ 1849.1ꢀ
‐723ꢀ 914.2ꢀ 916.3ꢀ ꢀ 1847.1ꢀ 1849.2ꢀ
‐823ꢀ 914.1ꢀ 916.2ꢀ ꢀ 1846.9ꢀ 1849.0ꢀ
‐923ꢀ 914.1ꢀ 916.4ꢀ ꢀ 1846.9ꢀ 1849.2ꢀ
‐1023ꢀ 914.0ꢀ 916.4ꢀ ꢀ 1846.8ꢀ 1849.2ꢀ
932.7ꢀ
932.9ꢀ
932.8ꢀ
932.8ꢀ
932.8ꢀ
41.3
45.5
36.9
35.1
47.6
Cu/SiO
Reactionꢀ conditions:ꢀ p(H
(mol/mol),ꢀLHSVꢀ=ꢀ1.8ꢀh .ꢀ
ꢀ
2
)ꢀ =ꢀ 2.0ꢀ MPa,ꢀ Tꢀ =ꢀ 473ꢀ K,ꢀ H /DEMꢀ =ꢀ 440
2
aꢀ
−1
Kineticꢀenergy.ꢀ
Augerꢀparameter.ꢀ
bꢀ
cꢀ
BindingꢀenergyꢀofꢀCu.ꢀ
Fromꢀ XRDꢀ measurementsꢀ (Fig.ꢀ 8),ꢀ theꢀ Cuꢀ particleꢀ sizeꢀ in‐
creasesꢀ fromꢀ 13.8ꢀ nmꢀ afterꢀ reductionꢀ toꢀ 36.1ꢀ nmꢀ afterꢀ DEMꢀ
hydrogenationꢀ (deactivation)ꢀ owingꢀ toꢀ aggregationꢀ ofꢀ copperꢀ
species.ꢀTEMꢀimagesꢀofꢀreducedꢀandꢀdeactivatedꢀcatalystsꢀareꢀ
shownꢀ inꢀ Fig.ꢀ 9.ꢀ Copperꢀ particlesꢀ areꢀ uniformlyꢀ dispersedꢀ onꢀ
dꢀ
+
+
0
+
Peakꢀareaꢀratio,ꢀXCu ꢀ=ꢀCu /(Cu ꢀ+ꢀCu ).ꢀ
ꢀ
intensityꢀratioꢀobtainedꢀbyꢀfittingꢀtheꢀCuꢀLMMꢀpeaksꢀincreasesꢀ
whenꢀincreasingꢀtheꢀcalcinationꢀtemperatureꢀfromꢀ623ꢀtoꢀ723ꢀ
K.ꢀCombiningꢀwithꢀtheꢀFT‐IRꢀanalysis,ꢀthereꢀwereꢀmoreꢀcopperꢀ
theꢀCu/SiO
afterꢀ deactivation.ꢀ Largeꢀ copperꢀ particlesꢀ withꢀ anꢀ averageꢀ di‐
ameterꢀ upꢀ toꢀ 90ꢀ nmꢀ areꢀ presentꢀ overꢀ theꢀ usedꢀ Cu/SiO ‐723ꢀ
2
‐723ꢀcatalystꢀafterꢀreductionꢀandꢀtheyꢀagglomerateꢀ
+
2
phyllosilicateꢀ inꢀ Cu/SiO ‐723,ꢀ soꢀ moreꢀ Cu ꢀ canꢀ beꢀ obtained.ꢀ
AlthoughꢀnoꢀcopperꢀphyllosilicateꢀisꢀpresentꢀinꢀCu/SiO
2
‐1023,ꢀ
+
2
highestꢀamountꢀofꢀCu ꢀcanꢀbeꢀascribedꢀtoꢀtheꢀreductionꢀdifficul‐
tyꢀofꢀaggregatedꢀCuO.ꢀ ꢀ
catalyst.ꢀWeꢀconcludeꢀthatꢀaggregationꢀofꢀcopperꢀparticlesꢀisꢀtheꢀ
mainꢀfactorꢀforꢀcatalystꢀdeactivationꢀ[44,45].ꢀHowever,ꢀcopperꢀ
phyllosilicateꢀ canꢀ enhanceꢀ dispersionꢀ ofꢀ copperꢀ speciesꢀ andꢀ
interactionꢀbetweenꢀcopperꢀandꢀtheꢀsupportꢀ[42],ꢀleadingꢀtoꢀtheꢀ
relativelyꢀ long‐termꢀ catalyticꢀ stabilityꢀ ofꢀ 99ꢀ hꢀ forꢀ theꢀ
3.7.ꢀ ꢀ Catalystꢀevaluationꢀ
Vapor‐phaseꢀ DEMꢀ hydrogenationꢀ toꢀ 1,3‐PDOꢀ involvesꢀ sev‐
2
Cu/SiO ‐723ꢀcatalyst.ꢀ
eralꢀ cascadeꢀ reactions,ꢀ includingꢀ hydrogenationꢀ ofꢀ DEMꢀ toꢀ
‐hydroxyethylꢀpropionateꢀ(3‐HPE)ꢀasꢀanꢀintermediate,ꢀhydro‐
genationꢀ ofꢀ 3‐HPEꢀ toꢀ 1,3‐PDO,ꢀ andꢀ deepꢀ hydrogenationꢀ ofꢀ
,3‐PDOꢀtoꢀn‐propanolꢀ(NPA)ꢀ(Schemeꢀ1).ꢀTheꢀethylꢀpropionateꢀ
EP)ꢀ byproductꢀ isꢀ synthesizedꢀ byꢀ furtherꢀ hydrogenationꢀ ofꢀ
‐HPE.ꢀ
DEMꢀ conversionꢀ andꢀ 1,3‐PDOꢀ selectivityꢀ overꢀ theꢀ Cu/SiO
3
100
7
5
0
1
(
3
80
60
40
20
0
6
2
ꢀ
45
30
15
0
catalystsꢀareꢀsummarizedꢀinꢀTableꢀ3.ꢀAllꢀofꢀtheꢀcatalystsꢀshowꢀ
highꢀconversionꢀ(>ꢀ90%)ꢀofꢀDEM,ꢀindicatingꢀtheꢀhighꢀactivityꢀofꢀ
Cu/SiO ꢀ catalystsꢀ preparedꢀ byꢀ theꢀ ammoniaꢀ evaporationꢀ
2
method.ꢀDEMꢀconversionꢀincreasesꢀwithꢀincreasingꢀamountꢀofꢀ
0
Cu ꢀandꢀisꢀtheꢀhighestꢀforꢀtheꢀCu/SiO
2
‐923ꢀcatalyst.ꢀTheꢀselec‐
tivityꢀ ofꢀ 1,3‐PDOꢀ increasesꢀ whenꢀ increasingꢀ theꢀ calcinationꢀ
temperatureꢀfromꢀ623ꢀtoꢀ723ꢀK,ꢀandꢀthenꢀdecreasesꢀwhenꢀtheꢀ
calcinationꢀtemperatureꢀisꢀfurtherꢀincreasedꢀtoꢀ1023ꢀK.ꢀAmongꢀ
0
20
40
60
80
100
Reaction time (h)
Fig.ꢀ7.ꢀCatalyticꢀperformanceꢀofꢀtheꢀCu/SiO
ofꢀ reactionꢀ time.ꢀ Reactionꢀ conditions:ꢀ p(H
2
‐723ꢀcatalystꢀasꢀaꢀfunctionꢀ
theꢀ catalystsꢀ used,ꢀ Cu/SiO
withꢀ1,3‐PDOꢀ selectivityꢀofꢀ 32.3%.ꢀ Theꢀ selectivityꢀofꢀ3‐HPEꢀisꢀ
theꢀ highestꢀ forꢀ Cu/SiO ‐923.ꢀ Theꢀ selectivityꢀ ofꢀ 1,3‐PDOꢀ de‐
2
‐723ꢀ showsꢀ theꢀ bestꢀ performanceꢀ
2
)ꢀ =ꢀ 2.0ꢀ MPa,ꢀ Tꢀ =ꢀ 473ꢀ K,ꢀ
−1
2
H /DEMꢀ=ꢀ330ꢀ(mol/mol),ꢀLHSVꢀ=ꢀ1.8ꢀh .ꢀ
2
creasesꢀ withꢀ increasingꢀ selectivityꢀ ofꢀ NPAꢀ andꢀ EP,ꢀ indicatingꢀ
thatꢀinhibitionꢀofꢀoverꢀhydrogenationꢀisꢀtheꢀkeyꢀfactorꢀforꢀcata‐
lystꢀmodification.ꢀ
Becauseꢀstabilityꢀisꢀcriticalꢀforꢀpracticalꢀapplicationꢀofꢀcata‐
lystsꢀforꢀDEMꢀhydrogenation,ꢀtheꢀlong‐termꢀperformanceꢀofꢀtheꢀ
Cu
Cu
2
O
SiO
2
optimalꢀcatalystꢀCu/SiO
2
‐723ꢀwasꢀinvestigated.ꢀAsꢀshownꢀinꢀFig.ꢀ
(2)
7
,ꢀtheꢀCu/SiO ‐723ꢀcatalystꢀremainedꢀstableꢀforꢀaboutꢀ99ꢀhꢀun‐
2
derꢀtheꢀoptimumꢀreactionꢀconditions.ꢀWhenꢀtheꢀreactionꢀtimeꢀ
increasedꢀtoꢀ104ꢀh,ꢀDEMꢀconversionꢀdecreasedꢀtoꢀ74.1%ꢀandꢀ
theꢀ1,3‐PDOꢀyieldꢀdecreasedꢀtoꢀ26.7%.ꢀ
(1)
10
20
30
40
/( )
50
60
70
80
o
2
Fig.ꢀ8.ꢀXRDꢀpatternsꢀofꢀtheꢀCu/SiO
2)ꢀafterꢀdeactivation.ꢀ
2
‐723ꢀcatalystꢀ(1)ꢀafterꢀreductionꢀand
Schemeꢀ1.ꢀHydrogenationꢀofꢀDEMꢀtoꢀ3‐HPE,ꢀ1,3‐PDO,ꢀandꢀn‐propanol.ꢀ
(

ꢀ
TongmeiꢀDingꢀetꢀal.ꢀ/ꢀChineseꢀJournalꢀofꢀCatalysisꢀ37ꢀ(2016)ꢀ484–493ꢀ
491ꢀ
+
Cu ,ꢀrespectively.ꢀ ꢀ
(
a)
(b)
Theꢀamountꢀofꢀcopperꢀphyllosilicateꢀincreasesꢀwhenꢀtheꢀcal‐
cinationꢀtemperatureꢀisꢀincreasedꢀfromꢀ623ꢀtoꢀ723ꢀK,ꢀresultingꢀ
inꢀaꢀstrongꢀinteractionꢀbetweenꢀcopperꢀandꢀsilica.ꢀTheꢀspecificꢀ
+
0
surfaceꢀ areaꢀ andꢀ ratioꢀ ofꢀ Cu /Cu ꢀ areꢀ theꢀ highestꢀ forꢀ theꢀ
Cu/SiO ‐723ꢀcatalyst.ꢀComparedꢀwithꢀtheꢀCu/SiO ‐723ꢀcatalyst,ꢀ
theꢀamountꢀofꢀcopperꢀphyllosilicateꢀandꢀCuꢀdispersionꢀdecreaseꢀ
forꢀtheꢀCu/SiO ‐823ꢀcatalyst,ꢀleadingꢀtoꢀaꢀsmallerꢀspecificꢀsur‐
2
2
2
Fig.ꢀ9.ꢀTEMꢀimagesꢀofꢀtheꢀCu/SiO
b)ꢀafterꢀdeactivation.ꢀ
2
‐723ꢀcatalystꢀ(a)ꢀafterꢀreductionꢀand
faceꢀareaꢀandꢀanꢀasymmetricalꢀreductionꢀpeakꢀinꢀtheꢀTPRꢀpro‐
file.ꢀ Copperꢀ phyllosilicateꢀ isꢀ notꢀ presentꢀ andꢀ CuOꢀ isꢀ wellꢀ dis‐
(
persedꢀonꢀtheꢀsurfaceꢀofꢀtheꢀCu/SiO
largeꢀspecificꢀ surfaceꢀareaꢀ andꢀaꢀ symmetricalꢀ reductionꢀ peak.ꢀ
AggregationꢀofꢀCuOꢀisꢀsevereꢀinꢀtheꢀCu/SiO ‐1023ꢀcatalystꢀandꢀ
blocksꢀtheꢀ poreꢀchannelsꢀofꢀ silica,ꢀ soꢀ reductionꢀofꢀ CuOꢀisꢀnotꢀ
efficient.ꢀ
2
‐923ꢀcatalyst,ꢀresultingꢀinꢀaꢀ
3
.8.ꢀ ꢀ Discussionꢀ
.8.1.ꢀ ꢀ FormationꢀofꢀcopperꢀphyllosilicateꢀonꢀcalcinedꢀCu/SiO
2
3
2
ꢀ
catalystsꢀ
Toupanceꢀ etꢀ al.ꢀ [46]ꢀ showedꢀ thatꢀ twoꢀ typesꢀ ofꢀ supportedꢀ
Cu ꢀspeciesꢀformedꢀinꢀcalcinedꢀsamples:ꢀgraftedꢀCu ꢀionsꢀandꢀ
copperꢀ phyllosilicate.ꢀ Bothꢀ Cu ꢀ speciesꢀ leadꢀ toꢀ smallꢀ metalꢀ
particlesꢀafterꢀreduction.ꢀGraftedꢀCu ꢀarisesꢀfromꢀelectrostaticꢀ
interactionꢀ betweenꢀ [Cu(NH
copperꢀphyllosilicateꢀisꢀsynthesizedꢀbyꢀtheꢀheterocondensationꢀ
reactionꢀofꢀSi(OH) ꢀwithꢀtheꢀCu(OH )(H O) ꢀcomplex.ꢀTrouilletꢀ
etꢀ al.ꢀ [47]ꢀ reportedꢀ thatꢀ CuIIꢀ complexesꢀ existꢀ asꢀ
2+
2+
3.8.3.ꢀ ꢀ ActiveꢀsitesꢀforꢀDEMꢀhydrogenationꢀ
2+
Theꢀoptimalꢀcatalyticꢀactivityꢀinvolvesꢀtheꢀcooperativeꢀeffectꢀ
2+
0
+
ofꢀCu ꢀandꢀCu ꢀtoꢀdissociateꢀhydrogenꢀandꢀactivateꢀDMOꢀ[27].ꢀItꢀ
2+
−
0
+
3 2
)
] ꢀ andꢀ twoꢀ SiO ꢀ groups,ꢀ whileꢀ
hasꢀbeenꢀsuggestedꢀthatꢀaꢀsuitableꢀratioꢀofꢀCu /Cu ꢀcanꢀgreatlyꢀ
improveꢀtheꢀcatalyticꢀperformanceꢀ[14,20].ꢀTheꢀcatalyticꢀstabil‐
ityꢀ isꢀ greatlyꢀ enhancedꢀ byꢀ boricꢀ acidꢀ withꢀ anꢀ optimalꢀ Cu/Bꢀ
atomicꢀratio,ꢀbecauseꢀofꢀformationꢀandꢀpreservationꢀofꢀappro‐
priateꢀdistributionsꢀofꢀCu ꢀandꢀCu ꢀspeciesꢀonꢀtheꢀcatalystꢀsur‐
faceꢀ[24].ꢀYinꢀetꢀal.ꢀ[39,40,49]ꢀshowedꢀthatꢀmetallicꢀCuꢀandꢀCu+ꢀ
4
2
2
4
2+
+
0
[Cu(NH
3 4
) (H
2
O)
2
] ꢀandꢀhaveꢀelectrostaticꢀinteractionsꢀwithꢀtheꢀ
silicaꢀ supportꢀ inꢀ solution,ꢀ whichꢀ canꢀ beꢀ transformedꢀ toꢀ
II
+
(≡SiO)
2
Cu (H
2 4
O) ꢀafterꢀcalcinationꢀinꢀair.ꢀCopperꢀphyllosilicateꢀ
areꢀresponsibleꢀforꢀtheꢀhighꢀcatalyticꢀefficiency.ꢀCu ꢀmayꢀplayꢀanꢀ
canꢀalsoꢀformꢀduringꢀtheꢀammoniaꢀevaporationꢀmethodꢀ[27].ꢀ
Inꢀtheꢀpresentꢀwork,ꢀtheꢀsilicaꢀsurfaceꢀandꢀmicrocrystallitesꢀ
ofꢀ theꢀ copperꢀ oxideꢀ precursorꢀ reactedꢀ toꢀ formꢀ diffi‐
cult‐to‐reduceꢀ copperꢀ phyllosilicate,ꢀ whichꢀ wasꢀ characterizedꢀ
byꢀ FT‐IRꢀ andꢀ TEM.ꢀ Theꢀ filandrousꢀ structureꢀ characteristicꢀ ofꢀ
copperꢀ phyllosilicateꢀ becameꢀ predominantꢀ onꢀ samplesꢀ pre‐
paredꢀatꢀ lowꢀcalcinationꢀtemperature.ꢀTheꢀrelativeꢀamountꢀofꢀ
copperꢀ phyllosilicateꢀ showedꢀ aꢀ volcano‐typeꢀ trendꢀ withꢀ in‐
creasingꢀ calcinationꢀ temperatureꢀ andꢀ wasꢀ maximumꢀ inꢀ theꢀ
importantꢀroleꢀinꢀtheꢀDMOꢀhydrogenationꢀreaction.ꢀMoreover,ꢀ
Cu ꢀmayꢀactꢀasꢀelectrophilicꢀorꢀLewisꢀacidꢀsitesꢀtoꢀpolarizeꢀtheꢀ
C=Oꢀ bondꢀ viaꢀ theꢀ loneꢀ pairꢀ onꢀ theꢀ oxygenꢀ atom,ꢀ therebyꢀ im‐
provingꢀtheꢀreactivityꢀofꢀtheꢀesterꢀgroupꢀinꢀDMOꢀ[50].ꢀInꢀmethylꢀ
+
acetateꢀhydrogenation,ꢀPoelsꢀetꢀal.ꢀ[51]ꢀreportedꢀthatꢀwhileꢀH ꢀ
2
0
+
dissociativelyꢀadsorbedꢀtoꢀCu ,ꢀCu ꢀstabilizedꢀmethoxyꢀandꢀacylꢀ
species,ꢀ whichꢀ areꢀ importantꢀ intermediatesꢀ inꢀ DMOꢀ hydro‐
2+
genation.ꢀ XRDꢀ andꢀ XPSꢀ characterizationsꢀ showedꢀ thatꢀ Cu ꢀ
couldꢀ beꢀ completelyꢀ absentꢀ afterꢀ reductionꢀ andꢀ abroadꢀ andꢀ
asymmetricꢀpeakꢀinꢀtheꢀCuꢀLMMꢀaugerꢀspectraꢀindicatedꢀthatꢀ
Cu/SiO
‐723ꢀcatalyst.ꢀItꢀwasꢀnotꢀpresentꢀwhenꢀtheꢀcalcinationꢀ
2
0
+
temperatureꢀ wasꢀ higherꢀ thanꢀ 923ꢀ K.ꢀ Whenꢀ theꢀ catalystꢀ wasꢀ
calcinedꢀatꢀ1023ꢀK,ꢀformationꢀofꢀlargeꢀCuOꢀparticlesꢀcanꢀbeꢀat‐
tributedꢀ toꢀ aggregationꢀ ofꢀ looselyꢀ boundꢀ well‐dispersedꢀ CuO.ꢀ
Formationꢀofꢀcopperꢀphyllosilicateꢀindicatesꢀtheꢀstrongꢀinterac‐
tionꢀbetweenꢀcopperꢀandꢀtheꢀsupport,ꢀandꢀtheꢀgoodꢀdispersionꢀ
Cu ꢀandꢀCu ꢀcoexistꢀinꢀtheꢀreducedꢀcatalysts.ꢀByꢀdeconvolutionꢀ
ofꢀtheꢀCuꢀLMMꢀaugerꢀspectra,ꢀtheꢀCu/SiO ‐723ꢀcatalystꢀshowedꢀ
2
+
+
0
theꢀ optimumꢀ Cu /(Cu +Cu )ꢀ ratioꢀ becauseꢀ ofꢀ theꢀ highestꢀ
amountꢀofꢀcopperꢀphyllosilicateꢀinꢀtheꢀcalcinedꢀsample,ꢀwhileꢀ
0
thereꢀwasꢀmoreꢀCu ꢀinꢀCu/SiO
2
‐923ꢀthanꢀinꢀtheꢀotherꢀcatalysts.ꢀ
ofꢀcopperꢀspecies,ꢀresultingꢀinꢀtheꢀCu/SiO
ingꢀtheꢀhighestꢀcatalyticꢀperformance.ꢀ ꢀ
2
‐723ꢀcatalystꢀshow‐
Activityꢀ resultsꢀ showedꢀ thatꢀ aꢀ catalystꢀ withꢀ aꢀ relativelyꢀ largeꢀ
+
0
+
ratioꢀofꢀCu /(Cu +Cu )ꢀcouldꢀincreaseꢀtheꢀselectivityꢀofꢀ1,3‐PDOꢀ
0
andꢀ moreꢀ Cu ꢀ couldꢀ increaseꢀ DEMꢀ conversion.ꢀ Therefore,ꢀ weꢀ
3.8.2.ꢀ ꢀ Copperꢀspeciesꢀafterꢀreductionꢀ
tentativelyꢀproposeꢀthatꢀtheꢀoptimalꢀcatalyticꢀactivityꢀoverꢀtheꢀ
Chenꢀ etꢀ al.ꢀ [27]ꢀ foundꢀ thatꢀ well‐dispersedꢀ CuOꢀ canꢀ beꢀ re‐
ducedꢀtoꢀCu ,ꢀandꢀcopperꢀphyllosilicateꢀcanꢀbeꢀreducedꢀtoꢀCu .ꢀ
VanꢀderꢀGriftꢀetꢀal.ꢀ[48]ꢀsuggestedꢀthatꢀcopperꢀphyllosilicateꢀandꢀ
Cu/SiO ‐723ꢀ catalystꢀ isꢀ becauseꢀ ofꢀ theꢀ synergeticꢀ effectꢀ be‐
tweenꢀCu ꢀandꢀCu ,ꢀandꢀmoreꢀCu ꢀcouldꢀenhanceꢀtheꢀreactivityꢀ
ofꢀ theꢀ esterꢀ groupꢀ inꢀ DEM.ꢀ Fromꢀ TPR,ꢀ theꢀ lowerꢀ reductionꢀ
2
0
+
0
+
+
+
0
well‐dispersedꢀCuOꢀcanꢀbeꢀreducedꢀtoꢀCu ꢀandꢀCu ,ꢀrespectively.ꢀ
temperatureꢀofꢀCu/SiO ‐723ꢀcatalystꢀindicatedꢀthatꢀitꢀcontainedꢀ
2
2
+
Toupanceꢀetꢀal.ꢀ[46]ꢀsuggestedꢀthatꢀgraftedꢀCu ꢀionsꢀandꢀcop‐
perꢀ phyllosilicateꢀ transformedꢀ toꢀ Cu ꢀ andꢀ Cu ,ꢀ respectively,ꢀ
moreꢀactiveꢀsites,ꢀleadingꢀtoꢀtheꢀhighestꢀcatalyticꢀperformance.ꢀ
Ammoniaꢀ evaporationꢀ isꢀ anꢀ effectiveꢀ wayꢀ toꢀ prepareꢀ theꢀ
0
+
2+
afterꢀreduction.ꢀInitially,ꢀ[Cu(NH
)
3 2
] ꢀadsorbsꢀonꢀtheꢀporeꢀsur‐
Cu/SiO ‐723ꢀcatalystꢀwithꢀhighꢀCuꢀloading,ꢀgoodꢀdispersionꢀofꢀ
2
faceꢀofꢀSiO ꢀbyꢀstrongꢀelectrostaticꢀadsorption.ꢀAfterꢀcalcination,ꢀ
2
copperꢀ species,ꢀ andꢀ largeꢀ copperꢀ surfaceꢀ area,ꢀ whichꢀ mayꢀ beꢀ
importantꢀ forꢀ theꢀ catalyticꢀ performance.ꢀ Theꢀ particlesꢀ ofꢀ
2+
graftedꢀ Cu ꢀ transformsꢀ toꢀ CuO,ꢀ andꢀ copperꢀ phyllosilicateꢀ
stronglyꢀadsorbsꢀonꢀtheꢀsilicaꢀsurfaceꢀbyꢀformationꢀofꢀCu–O–Siꢀ
bonds.ꢀFromꢀXPSꢀandꢀXRDꢀanalyses,ꢀunderꢀaꢀhydrogenꢀatmos‐
Cu/SiO ꢀcatalystsꢀcalcinedꢀatꢀtemperaturesꢀhigherꢀthanꢀ823ꢀKꢀ
2
couldꢀaggregate,ꢀleadingꢀtoꢀanꢀincreaseꢀofꢀtheꢀparticleꢀsizeꢀandꢀ
decreaseꢀofꢀtheꢀcopperꢀsurfaceꢀareaꢀandꢀcopperꢀdispersion.ꢀ
0
phere,ꢀCuOꢀandꢀcopperꢀphyllosilicateꢀcanꢀbeꢀreducedꢀtoꢀCu ꢀandꢀ

492ꢀ
TongmeiꢀDingꢀetꢀal.ꢀ/ꢀChineseꢀJournalꢀofꢀCatalysisꢀ37ꢀ(2016)ꢀ484–493ꢀ
4
.ꢀ ꢀ Conclusionsꢀ
L.ꢀGong,ꢀX.ꢀB.ꢀMa,ꢀJ.ꢀCatal.,ꢀ2013,ꢀ297,ꢀ142–150.ꢀ
12] B.ꢀ W.ꢀ Wang,ꢀ X.ꢀ Zhang,ꢀ Q.ꢀ Xu,ꢀ G.ꢀ H.ꢀ Xu,ꢀ Chin.ꢀ J.ꢀ Catal.,ꢀ 2008,ꢀ 29,ꢀ
75–280.ꢀ
13] S.ꢀR.ꢀWang,ꢀX.ꢀB.ꢀLi,ꢀQ.ꢀQ.ꢀYin,ꢀL.ꢀJ.ꢀZhu,ꢀZ.ꢀY.ꢀLuo,ꢀCatal.ꢀCommun.,ꢀ
011,ꢀ12,ꢀ1246–1250.ꢀ
14] L.ꢀZhao,ꢀY.ꢀJ.ꢀZhao,ꢀS.ꢀP.ꢀWang,ꢀH.ꢀR.ꢀYue,ꢀB.ꢀWang,ꢀJ.ꢀLv,ꢀX.ꢀB.ꢀMa,ꢀInd.ꢀ
Eng.ꢀChem.ꢀRes.,ꢀ2012,ꢀ51,ꢀ13935–13943.ꢀ
15] H.ꢀR.ꢀYue,ꢀY.ꢀJ.ꢀZhao,ꢀL.ꢀZhao,ꢀJ.ꢀLv,ꢀS.ꢀP.ꢀWang,ꢀJ.ꢀL.ꢀGong,ꢀX.ꢀB.ꢀMa,ꢀ
AIChEꢀJ.,ꢀ2012,ꢀ58,ꢀ2798–2809.ꢀ
[
[
[
[
[
2
Theꢀ calcinationꢀ temperatureꢀ hasꢀ aꢀ profoundꢀ effectꢀ onꢀ theꢀ
texture,ꢀ composition,ꢀ andꢀ structureꢀ ofꢀ Cu/SiO ꢀ catalystsꢀ pre‐
2
2
paredꢀbyꢀtheꢀammoniaꢀevaporationꢀmethod.ꢀCopperꢀspeciesꢀcanꢀ
reactꢀ withꢀ silicicꢀ acidꢀ toꢀ formꢀ copperꢀ phyllosilicate,ꢀ whichꢀ isꢀ
instrumentalꢀ inꢀ promotingꢀ dispersionꢀ ofꢀ copperꢀ speciesꢀ andꢀ
obtainingꢀ moreꢀ Cu ꢀ afterꢀ reduction.ꢀ Amongꢀ theꢀ catalystsꢀ pre‐
paredꢀ underꢀ differentꢀ calcinationꢀ temperature,ꢀ theꢀ
+
16] A.ꢀY.ꢀYin,ꢀC.ꢀWen,ꢀW.ꢀL.ꢀDai,ꢀK.ꢀN.ꢀFan,ꢀAppl.ꢀSurf.ꢀSci.,ꢀ2011,ꢀ257,ꢀ
5844–5849.ꢀ
Cu/SiO ‐723ꢀcatalystꢀshowedꢀtheꢀhighestꢀcatalyticꢀperformanceꢀ
2
forꢀDEMꢀconversionꢀofꢀ90.7%ꢀandꢀtheꢀhighestꢀ1,3‐PDOꢀselectiv‐
ityꢀofꢀ32.3%.ꢀTheꢀtrendꢀofꢀtheꢀcatalyticꢀactivityꢀwithꢀtheꢀratioꢀofꢀ
[17] C.ꢀWen,ꢀY.ꢀY.ꢀCui,ꢀW.ꢀL.ꢀDai,ꢀS.ꢀH.ꢀXie,ꢀK.ꢀN.ꢀFan,ꢀChem.ꢀCommun.,ꢀ
2013,ꢀ46,ꢀ5195–5197.ꢀ
[18] Y.ꢀJ.ꢀZhang,ꢀN.ꢀZheng,ꢀK.ꢀJ.ꢀWang,ꢀS.ꢀJ.ꢀZhang,ꢀJ.ꢀWu,ꢀJ.ꢀNanomater.,ꢀ
2013,ꢀ629375.ꢀ
+
0
+
0
Cu /(Cu +Cu )ꢀ suggestsꢀ aꢀ synergeticꢀ effectꢀ betweenꢀ Cu ꢀ andꢀ
+
Cu .ꢀMoreover,ꢀotherꢀfactorsꢀcouldꢀnotꢀbeꢀruledꢀout,ꢀsuchꢀasꢀtheꢀ
[
[
[
[
[
19] Y.ꢀY.ꢀZhu,ꢀS.ꢀR.ꢀWang,ꢀL.ꢀJ.ꢀZhu,ꢀX.ꢀL.ꢀGe,ꢀX.ꢀB.ꢀLi,ꢀZ.ꢀY.ꢀLuo,ꢀCatal.ꢀLett.,ꢀ
largerꢀspecificꢀsurfaceꢀarea,ꢀbetterꢀdispersionꢀofꢀcopperꢀspecies,ꢀ
largerꢀcupreousꢀsurfaceꢀarea,ꢀandꢀgreaterꢀnumberꢀofꢀactiveꢀsitesꢀ
2010,ꢀ135,ꢀ275–281.
20] X.ꢀB.ꢀMa,ꢀH.ꢀW.ꢀChi,ꢀH.ꢀR.ꢀYue,ꢀY.ꢀJ.ꢀZhao,ꢀY.ꢀXu,ꢀJ.ꢀLv,ꢀS.ꢀP.ꢀWang,ꢀJ.ꢀL.ꢀ
Gong,ꢀAIChEꢀJ.,ꢀ2013,ꢀ59,ꢀ2530–2539.ꢀ
21] A.ꢀY.ꢀYin,ꢀC.ꢀWen,ꢀW.ꢀL.ꢀDai,ꢀK.ꢀN.ꢀFan,ꢀAppl.ꢀCatal.ꢀB,ꢀ2011,ꢀ108–109,ꢀ
2
inꢀ theꢀ Cu/SiO ‐723ꢀ catalyst.ꢀ Theꢀ catalyticꢀ performanceꢀ ofꢀ theꢀ
Cu/SiO ‐723ꢀcatalystꢀinꢀgasꢀhydrogenationꢀremainedꢀstableꢀforꢀ
2
aboutꢀ99ꢀh.ꢀ
90–99.ꢀ
22] A.ꢀY.ꢀYin,ꢀX.ꢀY.ꢀGuo,ꢀK.ꢀN.ꢀFan,ꢀW.ꢀL.ꢀDai,ꢀChemCatChem,ꢀ2010,ꢀ2,ꢀ
Referencesꢀ
206–213.ꢀ
23] X.ꢀ Y.ꢀ Guo,ꢀ A.ꢀ Y.ꢀ Yin,ꢀ W.ꢀ L.ꢀ Dai,ꢀ K.ꢀ N.ꢀ Fan,ꢀ Catal.ꢀLett.,ꢀ 2009,ꢀ 132,ꢀ
[1] R.ꢀK.ꢀSaxena,ꢀP.ꢀAnand,ꢀS.ꢀSaran,ꢀJ.ꢀIsar,ꢀBiotechnol.ꢀAdv.,ꢀ2009,ꢀ27,ꢀ
22–27.ꢀ
8
95–913.ꢀ
[24] Z.ꢀHe,ꢀH.ꢀQ.ꢀLin,ꢀP.ꢀHe,ꢀY.ꢀZ.ꢀYuan,ꢀJ.ꢀCatal.,ꢀ2011,ꢀ277,ꢀ54–63.ꢀ
[25] A.ꢀY.ꢀYin,ꢀX.ꢀY.ꢀGuo,ꢀW.ꢀL.ꢀDai,ꢀK.ꢀN.ꢀFan,ꢀCatal.ꢀCommun.,ꢀ2011,ꢀ12,ꢀ
412–416.ꢀ
[
2] G.ꢀA.ꢀKraus,ꢀClean‐SoilꢀAirꢀWater,ꢀ2008,ꢀ36,ꢀ648–651.ꢀ
3] H.ꢀ J.ꢀ Liu,ꢀ Y.ꢀ Z.ꢀ Xu,ꢀ Z.ꢀ M.ꢀ Zheng,ꢀ D.ꢀ H.ꢀ Liu,ꢀ Biotechnol.ꢀ J.,ꢀ 2010,ꢀ 5,ꢀ
[
1
137–1148.ꢀ
[26] B.ꢀZhang,ꢀS.ꢀG.ꢀHui,ꢀS.ꢀH.ꢀZhang,ꢀY.ꢀJi,ꢀW.ꢀLi,ꢀD.ꢀY.ꢀFang,ꢀJ.ꢀNat.ꢀGasꢀ
Chem.,ꢀ2012,ꢀ21,ꢀ563–570.ꢀ
[
4] K.ꢀV.ꢀJoseph,ꢀJ.ꢀPolym.ꢀEnviron.,ꢀ2005,ꢀ13,ꢀ159–167.ꢀ
[
5] T.ꢀHaas,ꢀB.ꢀJaeger,ꢀR.ꢀWeber,ꢀS.ꢀF.ꢀMitchell,ꢀC.ꢀF.ꢀKing,ꢀAppl.ꢀCatal.ꢀA,ꢀ
[27] L.ꢀF.ꢀChen,ꢀP.ꢀJ.ꢀGuo,ꢀM.ꢀH.ꢀQiao,ꢀS.ꢀR.ꢀYan,ꢀH.ꢀX.ꢀLi,ꢀW.ꢀShen,ꢀH.ꢀL.ꢀXu,ꢀ
K.ꢀN.ꢀFan,ꢀJ.ꢀCatal.,ꢀ2008,ꢀ257,ꢀ172–180.ꢀ
2005,ꢀ280,ꢀ83–88.ꢀ
[
[
[
[
6] L.ꢀH.ꢀSlaugh,ꢀJ.ꢀP.ꢀArhancet,ꢀUSꢀPatentꢀ5ꢀ304ꢀ686,ꢀ1994.ꢀ
7] Y.ꢀZ.ꢀHan,ꢀWOꢀPatentꢀ2002ꢀ102ꢀ754ꢀA2,ꢀ2002.ꢀ
8] J.ꢀD.ꢀUnuh,ꢀD.ꢀA.ꢀRyan,ꢀI.ꢀNicolau,ꢀUSꢀPatentꢀ5ꢀ093ꢀ537,ꢀ1992.ꢀ
9] C.ꢀBrossmer,ꢀD.ꢀArntz,ꢀUSꢀPatentꢀ6140543,ꢀ2000.ꢀ
[28] F.ꢀLi,ꢀC.ꢀS.ꢀLu,ꢀX.ꢀN.ꢀLi,ꢀChin.ꢀChem.ꢀLett.,ꢀ2014,ꢀ25,ꢀ1461–1465.ꢀ
[29] Y.ꢀF.ꢀZhu,ꢀX.ꢀKong,ꢀD.ꢀB.ꢀCao,ꢀJ.ꢀL.ꢀCui,ꢀY.ꢀL.ꢀZhu,ꢀY.ꢀW.ꢀLi,ꢀACSꢀCatal.,ꢀ
2014,ꢀ4,ꢀ3675–3681.ꢀ
[30] P.ꢀYuan,ꢀZ.ꢀY.ꢀLiu,ꢀT.ꢀJ.ꢀHu,ꢀH.ꢀJ.ꢀSun,ꢀS.ꢀC.ꢀLiu,ꢀReact.ꢀKinet.ꢀMech.ꢀ
Catal.,ꢀ2010,ꢀ100,ꢀ427–439.ꢀ
[
10] H.ꢀJ.ꢀWang,ꢀG.ꢀQ.ꢀGao,ꢀY.ꢀLiu,ꢀCNꢀPatentꢀ101134713,ꢀ2008.ꢀ
[11] S.ꢀZhao,ꢀH.ꢀR.ꢀYue,ꢀY.ꢀJ.ꢀZhao,ꢀB.ꢀWang,ꢀY.ꢀC.ꢀGeng,ꢀJ.ꢀLv,ꢀS.ꢀP.ꢀWang,ꢀJ.ꢀ
[31] W.ꢀB.ꢀLi,ꢀM.ꢀZhuang,ꢀJ.ꢀX.ꢀWang,ꢀCatal.ꢀToday,ꢀ2008,ꢀ137,ꢀ340–344.ꢀ
GraphicalꢀAbstractꢀ
Chin.ꢀJ.ꢀCatal.,ꢀ2016,ꢀ37:ꢀ484–493ꢀ ꢀ ꢀ doi:ꢀ10.1016/S1872‐2067(15)61053‐1
HighlyꢀactiveꢀCu/SiO ꢀcatalystsꢀforꢀhydrogenationꢀofꢀdiethylꢀmalonateꢀtoꢀ1,3‐propanediolꢀ
2
ꢀ
TongmeiꢀDing,ꢀHengshuiꢀTian*,ꢀJichangꢀLiu,ꢀWenbinꢀWu,ꢀJintaoꢀYuꢀ
EastꢀChinaꢀUniversityꢀofꢀScienceꢀandꢀTechnologyꢀ
SiO2
CuO
Chrysocolla
1023 K
9
23 K
23 K
23 K
23 K
8
7
6
10
20
30
40
 /(
50
60
70
80
o
2
)
Cu/SiO
2
ꢀcatalystsꢀpreparedꢀviaꢀtheꢀammoniaꢀevaporationꢀmethodꢀwereꢀappliedꢀinꢀdiethylꢀmalonateꢀhydrogenation.ꢀTheꢀoptimumꢀcatalyticꢀ
ꢀcalcinedꢀatꢀ723ꢀK,ꢀacquiringꢀbetterꢀcopperꢀspeciesꢀdispersion,ꢀlargerꢀcupreousꢀsurfaceꢀareaꢀ
performanceꢀcouldꢀbeꢀobtainedꢀoverꢀCu/SiO
andꢀlargerꢀratioꢀofꢀCu /Cu .ꢀ
2
+
0

ꢀ
TongmeiꢀDingꢀetꢀal.ꢀ/ꢀChineseꢀJournalꢀofꢀCatalysisꢀ37ꢀ(2016)ꢀ484–493ꢀ
493ꢀ
[32] Y.ꢀH.ꢀChoi,ꢀW.ꢀY.ꢀLee,ꢀCatal.ꢀLett.,ꢀ2000,ꢀ67,ꢀ155–161.ꢀ
2013,ꢀ303,ꢀ70–79.ꢀ
[33] S.ꢀKaneko,ꢀM.ꢀIzuka,ꢀA.ꢀTakahashi,ꢀ M.ꢀ Ohshima,ꢀH.ꢀKurokawa,ꢀH.ꢀ
Miura,ꢀAppl.ꢀCatal.ꢀA,ꢀ2012,ꢀ427–428,ꢀ85–91.ꢀ
[43] M.ꢀA.ꢀKohler,ꢀH.ꢀE.ꢀCurry‐Hyde,ꢀA.ꢀE.ꢀHughes,ꢀB.ꢀA.ꢀSexton,ꢀN.ꢀW.ꢀ
Cant,ꢀJ.ꢀCatal.,ꢀ1987,ꢀ108,ꢀ323–333.ꢀ
[
[
[
[
34] Y.ꢀY.ꢀZhu,ꢀS.ꢀR.ꢀWang,ꢀL.ꢀJ.ꢀZhu,ꢀX.ꢀL.ꢀGe,ꢀX.ꢀB.ꢀLi,ꢀZ.ꢀY.ꢀLuo,ꢀCatal.ꢀLett.,ꢀ
[44] E.ꢀ S.ꢀ Vasiliadou,ꢀ A.ꢀ A.ꢀ Lemonidou,ꢀ Appl.ꢀ Catal.ꢀ A,ꢀ 2011,ꢀ 396,ꢀ
177–185.ꢀ
[45] S.ꢀ Panyad,ꢀ S.ꢀ Jongpatiwut,ꢀ T.ꢀ Sreethawong,ꢀ T.ꢀ Rirksomboon,ꢀ S.ꢀ
Osuwan,ꢀCatal.ꢀToday,ꢀ2011,ꢀ174,ꢀ59–64.ꢀ
[46] T.ꢀToupance,ꢀM.ꢀKermarec,ꢀJ.ꢀF.ꢀLambert,ꢀC.ꢀLouis,ꢀJ.ꢀPhys.ꢀChem.ꢀB,ꢀ
2002,ꢀ106,ꢀ2277–2286.ꢀ
[47] L.ꢀ Trouillet,ꢀ T.ꢀ Toupance,ꢀ F.ꢀ Villain,ꢀ C.ꢀ Louis,ꢀ Phys.ꢀ Chem.ꢀ Chem.ꢀ
Phys.,ꢀ2000,ꢀ2,ꢀ2005–2014.ꢀ
2
010,ꢀ135,ꢀ275–281.ꢀ
35] A.ꢀY.ꢀYin,ꢀX.ꢀY.ꢀGuo,ꢀW.ꢀL.ꢀDai,ꢀH.ꢀX.ꢀLi,ꢀK.ꢀN.ꢀFan,ꢀAppl.ꢀCatal.ꢀA,ꢀ2008,ꢀ
49,ꢀ91–99.ꢀ ꢀ
3
36] C.ꢀWen,ꢀA.ꢀY.ꢀYin,ꢀY.ꢀY.ꢀCui,ꢀX.ꢀL.ꢀYang,ꢀW.ꢀL.ꢀDai,ꢀK.ꢀN.ꢀFan,ꢀAppl.ꢀ
Catal.ꢀA,ꢀ2013,ꢀ458,ꢀ82–89.ꢀ ꢀ ꢀ
37] J.ꢀChaminand,ꢀL.ꢀDjakovitch,ꢀP.ꢀGallezot,ꢀP.ꢀMarion,ꢀC.ꢀPinel,ꢀC.ꢀRos‐
ier,ꢀGreenꢀChem.,ꢀ2004,ꢀ6,ꢀ359–361.ꢀ
[
38] S.ꢀF.ꢀJi,ꢀT.ꢀL.ꢀJiang,ꢀK.ꢀXu,ꢀS.ꢀB.ꢀLi,ꢀAppl.ꢀSurf.ꢀSci.,ꢀ1998,ꢀ133,ꢀ231–238.ꢀ
39] A.ꢀY.ꢀYin,ꢀX.ꢀY.ꢀGuo,ꢀW.ꢀL.ꢀDai,ꢀK.ꢀN.ꢀFan,ꢀJ.ꢀPhys.ꢀChem.ꢀC,ꢀ2009,ꢀ113,ꢀ
[48] C.ꢀJ.ꢀG.ꢀVanꢀderꢀGrift,ꢀA.ꢀMulder,ꢀJ.ꢀW.ꢀGeus,ꢀAppl.ꢀCatal.,ꢀ1990,ꢀ60,ꢀ
181–192.ꢀ
[
1
1003–11013.ꢀ
40] A.ꢀ Y.ꢀ Yin,ꢀJ.ꢀW.ꢀQu,ꢀX.ꢀ Y.ꢀ Guo,ꢀW.ꢀ L.ꢀDai,ꢀK.ꢀN.ꢀ Fan,ꢀ Appl.ꢀCatal.ꢀA,ꢀ
011,ꢀ400,ꢀ39–47.ꢀ
41] D.ꢀ S.ꢀ Brands,ꢀ E.ꢀ K.ꢀ Poels,ꢀ A.ꢀ Bliek,ꢀ Appl.ꢀ Catal.ꢀ A,ꢀ 1999,ꢀ 184,ꢀ
79–289.ꢀ
42] S.ꢀH.ꢀZhu,ꢀX.ꢀQ.ꢀGao,ꢀY.ꢀL.ꢀZhu,ꢀY.ꢀF.ꢀZhu,ꢀH.ꢀY.ꢀZheng,ꢀY.ꢀW.ꢀLi,ꢀJ.ꢀCatal.,ꢀ
[49] A.ꢀY.ꢀYin,ꢀX.ꢀY.ꢀGuo,ꢀW.ꢀL.ꢀDai,ꢀK.ꢀN.ꢀFan,ꢀJ.ꢀPhys.ꢀChem.ꢀC,ꢀ2010,ꢀ114,ꢀ
8523–8532.ꢀ
[50] M.ꢀ Bartók,ꢀ Á.ꢀ Molnár,ꢀ in:ꢀ S.ꢀ Pataiꢀ ed.,ꢀ Theꢀ Chemistryꢀ ofꢀ Dou‐
ble‐BondedꢀFunctionalꢀGroupsꢀ(SupplementꢀA3),ꢀWiley,ꢀNewꢀYork,ꢀ
1997,ꢀ16ꢀ ꢀ
[
[
[
2
2
[51] E.ꢀK.ꢀPoels,ꢀD.ꢀS.ꢀBrands,ꢀAppl.ꢀCatal.ꢀA,ꢀ2000,ꢀ191,ꢀ83–96.ꢀ