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1、ABSTRACTTheuseoffossilfuelssuchascoal,oilandnaturalgasgeneratealotofsulfurdioxideandsootemissions,causingseriouspollutionofacidrainandairpollution.Withtheunderstandingofhumanontheenvironmentalpollutionandresourcecrisisdeepening,renewable,biodegradableandotherpropertie
2、sofnaturalpolymer,ispaidincreasingattention.Ligninisanimportantrenewablecarbonsourceandtheuseoflignintoproducebio-oilandhighvalue-addedchemicalshavebeenwidelystudied.Fastpyrolysisofligninyieldsoxygen-richbio-oils,suchasphenols,anisoles,guaiacolsandsyringols,whichisins
3、tability,viscosityandcorrosive.Inordertoupgradebio-oils,hydrodeoxygenation(HDO)isneededtomaketheseproductsasconventionalfuels’substitutes.Hydrodeoxygenationactivityofphenolicsoverbifunctionalcatalystishigh,butthespecificreactionrouteisnotclear,thepurposeofthisworkisto
4、gaininsightsintothereactionpathwayofhydrodeoxygenationofphenolicsoveraPt/HBetacatalyst.Hydrodeoxygenationofm-cresolhasbeenstudiedonaPt/HBetacatalystat225-350°Candambienthydrogenpressure.At250°C,m-cresolconversionproceedsthroughtworeactionpathways:(1)directdeoxygenatio
5、n(DDOpath)totoluene,and(2)hydrogenationofm-cresoltomethylcyclohexanoneandmethylcyclohexanolonPt,followedbyfastdehydrationontheBrønstedacidsitestomethylcyclohexene(HYDpath),whichiseitherhydrogenatedtomethylcyclohexaneonPtorringcontractedtodimethylcyclopentanesandethylc
6、yclopentaneontheBrønstedacidsites.Asthedehydrationofmethylcyclohexanolismuchfasterthantheinitialhydrogenationofm-cresol,theinitialhydrogenationistherate-determiningstepoftheHYDpath.Increasingtemperatureto350°CleadstotheDDOpathbecomingthedominantpathtotoluene,whiletheH
7、YDpathfollowedbyfastequilibrationtotoluenelessimportant.TheapparentactivationenergyoftheDDOpathis49.7kJ/molbutbecomesnegativefortheHYDpath.Consequently,increasingtemperatureenhancesthecontributionfromtheDDOpathbutreducesthatfromtheHYDpaththroughinhibitingtheinitialhyd
8、rogenationofm-cresol.Inordertoexploretheinfluenceofsupportonthecatalyticreaction,threedifferentacidicBetazeolitecatalysts(Pt
