Pt/TiO_2催化间甲基苯酚加氢脱氧路径探究
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摘要
通过等体积浸渍法制备了催化剂Pt/TiO_2。利用间甲基苯酚及其中间产物(甲基环己酮、甲基环己醇、甲基环己烷和甲苯等)在催化剂Pt/TiO_2上的反应探究了甲基苯酚加氢脱氧的反应路径。利用XRD、H_2-TPR、TEM、NH_3-TPD、XPS等对催化剂的表面性质和结构性质进行了表征。结果表明,金属Pt能高度分散在载体TiO_2上。Pt/TiO_2催化间甲基苯酚加氢脱氧反应主要存在2种路径:一种是间甲基苯酚直接脱氧生成甲苯(DDO路径);另一种是间甲基苯酚先加氢生成甲基环己酮、甲基环己醇,然后脱水生成甲基环己烯,再加氢生成甲基环己烷。
Pt/TiO_2 catalyst is prepared by incipient wetness impregnation. In order to get the reaction pathways of m-cresol hydrodeoxygenation,m-cresol and its intermediate products such as methyl cyclohexanone,methyl cyclohexanol,methyl cyclohexane and toluene are investigated over Pt/TiO_2 catalyst at 250 ℃ and ambient hydrogen pressure. The structures and properties of Pt/TiO_2 is also investigated by various techniques such as XRD,TEM,BET,XPS,CO chemisorption,NH_3-TPD,H_2-TPR etc.It is found that Pt particles disperse highly onto the TiO_2 supporter.There are two main reaction pathways for hydrodeoxygenation of m-cresol. The first one is the direct deoxygenation to toluene( DDO path) and the second one is that hydrodeoxygenation of m-cresol forms firstly methylcyclohexanone and methylcyclohexanol over Pt,then these two intermediates perform rapidly dehydration to gain methylcyclohexene that is again hydrogenated to methylcyclohexane.Among these two pathways,DDO path is predominant.
Pt/TiO_2 catalyst is prepared by incipient wetness impregnation. In order to get the reaction pathways of m-cresol hydrodeoxygenation,m-cresol and its intermediate products such as methyl cyclohexanone,methyl cyclohexanol,methyl cyclohexane and toluene are investigated over Pt/TiO_2 catalyst at 250 ℃ and ambient hydrogen pressure. The structures and properties of Pt/TiO_2 is also investigated by various techniques such as XRD,TEM,BET,XPS,CO chemisorption,NH_3-TPD,H_2-TPR etc.It is found that Pt particles disperse highly onto the TiO_2 supporter.There are two main reaction pathways for hydrodeoxygenation of m-cresol. The first one is the direct deoxygenation to toluene( DDO path) and the second one is that hydrodeoxygenation of m-cresol forms firstly methylcyclohexanone and methylcyclohexanol over Pt,then these two intermediates perform rapidly dehydration to gain methylcyclohexene that is again hydrogenated to methylcyclohexane.Among these two pathways,DDO path is predominant.
引文
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[2]Patwardhan P R,Brown R C,Shanks B H.Understanding the fast pyrolysis of lignin[J].Chem Sus Chem,2011,4(11):1629-1636.
[3]Saidi M,Samimi F,Karimipourfard D,et al.Upgrading of lignin-derived bio-oils by catalytic hydrodeoxygenation[J].Energy Environ Sci,2014,7(1):103-129.
[4]Steven Crossley J F,Min Shen,Daniel E Resasco.Solid nanoparticles that catalyze biofuel upgrade reactions at the water/oil Interface[J].Science,2010,327(5961):68-72.
[5]方新,湘白云,陈爱华,等.绿色可再生能源之生物质能源[J].现代化工,2008,28(S2):21-25.
[6]Chen C,Chen G,Yang F,et al.Vapor phase hydrodeoxygenation and hydrogenation of m-cresol on silica supported Ni,Pd and Pt catalysts[J].Chemical Engineering Science,2008,135:145-154.
[7]Sun Q,Chen G,Wang H,et al.Insights into the major reaction pathways of vapor-phase hydrodeoxygenation of m-cresol on a Pt/H beta catalyst[J].Chem Cat Chem,2016,8(3):551-561.
[8]Hart D C E A T R.Catalytic hydroprocessing of chemical models for bio-oil[J].Energy&Fuels,2009,23(1):631-637.
[9]Sandoval A,Gómez-Cortés A,Zanella R,et al.Gold nanoparticles:Support effects for the WGS reaction[J].Journal of Molecular Catalysis A:Chemical,2007,278(1):200-208.
[10]He Z,Wang X.Required catalytic properties for alkane production from carboxylic acids:Hydrodeoxygenation of acetic acid[J].Journal of Energy Chemistry,2013,22(6):883-894.
[11]Nguyen T S,Laurenti D,Afanasiev P,et al.Titania-supported goldbased nanoparticles efficiently catalyze the hydrodeoxygenation of guaiacol[J].Journal of Catalysis,2016,344(1):136-140.
[12]Nie L,Peng B,Zhu X.Vapor-phase hydrodeoxygenation of guaiacol to aromatics over Pt/H beta:Identification of the role of acid sites and metal sites on the reaction pathway[J].Chem Cat Chem,2018,10(5):1064-1074.
[13]Robinson A,Ferguson G A,Gallagher J R,et al.Enhanced hydrodeoxygenation of m-cresol over bimetallic Pt-Mo catalysts through an oxophilic metal-induced tautomerization pathway[J].ACSCatalysis,2016,6(7):4356-4368.
[14]De Souza P M,Rabelo-Neto R C,Borges L E P,et al.Role of keto intermediates in the hydrodeoxygenation of phenol over Pd on oxophilic supports[J].ACS Catalysis,2015,5(2):1318-1329.
[15]De Souza P M,Rabelo-Neto R C,Borges L E P,et al.Hydrodeoxygenation of phenol over Pd catalysts.Effect of support on reaction mechanism and catalyst deactivation[J].ACS Catalysis,2018,7(3):2058-2073.
[16]Yang F,Liu D,Wang H,et al.Geometric and electronic effects of bimetallic Ni-Re catalysts for selective deoxygenation of m-cresol to toluene[J].Journal of Catalysis,2017,349:84-97.
[17]Zhu X,Lobban L L,Mallinson R G,et al.Bifunctional transalkylation and hydrodeoxygenation of anisole over a Pt/HBeta catalyst[J].Journal of Catalysis,2011,281(1):21-29.
[18]Ohno T,Sarukawa K,Tokieda K,et al.Morphology of a Ti O2photocatalyst(Degussa,P25)consisting of anatase and rutile crystalline phases[J].Journal of Catalysis,2011,203(1):82-86.
[19]Ding G Q L Z,Greenfield P F.Role of the crystallite phase of Ti O2in heterogeneous photocatalysis for phenol oxidation in water[J].The Journal of Physical Chemistry B,2000,104(19):4815-4820.
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[21]Resendea N S,Jean-Guillaume Eon,Martin Schmal B.Pt-TiO2-γAl2O3catalystⅠ.Dispersion of platinum on alumina-grafted titanium oxide[J].Journal of Catalysis,1998,83(1):6-13.
[22]Epling W S,Cheekatamarla P K,Lane A M.Reaction and surface characterization studies of titania-supported Co,Pt and Co/Pt catalysts for the selective oxidation of CO in H2-containing streams[J].Chemical Engineering Journal,2003,93(1):61-68.
[23]Pérez-Hernndez R,Gómez-Cortés A,Arenas-Alatorre J,et al.Díaz,SCR of NO by CH4on Pt/Zr O2-Ti O2sol-gel catalysts[J].Catalysis Today,2005,107-108:149-156.
[24]Wang J A,Cuan A,Salmones J,et al.Studies of sol-gel Ti O2and Pt/Ti O2catalysts for NO reduction by CO in an oxygen-rich condition[J].Applied Surface Science,2004,230(1-4):94-105.
[25]Giovanni Bagnasco.Improving the Selectivity of NH3-TPD Measurements[J].Journal of Catalysis,1996,159(1):249-252.
[26]Gianmario Martra.Lewis acid and base sites at the surface of microcrystalline Ti O2anatase relationships between surface morphology and chemical behaviour[J].Applied Catalysis A:General,2000,200(1-2):275-285.
[27]Guillemot F,PortéM C,Labrugère C,et al.Ti4+to Ti3+conversion of Ti O2uppermost layer by low-temperature vacuum annealing:Interest for titanium biomedical applications[J].Journal of Colloid and Interface Science,2002,255(1):75-78.
[28]Zhang X,Tian H,Wang X,et al.The role of oxygen vacancy-Ti3+states on Ti O2nanotubes'surface in dye-sensitized solar cells[J].Materials Letters,2013,100(1):51-53.