MoO_3催化剂上苯酚加氢脱氧制取芳烃研究
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摘要
以(NH_4)_6Mo_7O_(24)·4H_2O为前驱体通过简单的焙烧方法制备非负载型MoO_3催化剂,通过低温N_2吸附、X射线衍射(XRD)、X射线光电子能谱(XPS)和H_2程序升温还原(H_2-TPR)技术对催化剂特性进行表征,以苯酚为模型化合物进行加氢脱氧实验制备以苯为主要产物的芳烃化学品。重点考察反应温度、反应时间、反应气组成等参数对苯酚转化率、目标产物苯选择性的影响,并就氧化钼催化加氢脱氧反应机制及催化剂的可重复使用性能进行讨论与考察。实验结果表明,在340℃、0.5 MPa H_2与3.0 MPa N_2混合气氛的优化工况下,苯酚的转化率达到98.1%,产物苯选择性达到99.5%。MoO_3催化材料中的氧缺陷位是催化苯酚分子中C_(AR)—OH键直接氢解生成芳烃苯的主要活性位。此外,MoO_3重复使用3次后催化活性仍无明显下降,表明该催化剂的加氢脱氧催化活性具有良好的稳定性。
MoO_3 catalyst was prepared by calcination using(NH_4)_6 Mo_7 O_(24)·4 H_2 O as precursor and was characterized by XRD,XPS, H_2-TPR and low temperature N_2 adsorption. Aim to produce arene, hydrodeoxygenation(HDO) was carried out using phenol as model compound. The focus was the effects of reaction temperature, reaction time and reaction gas conposition on the phenol conversion rate and selectivity of target product. The catalytic mechanism of phenol HDO over MoO_3 and the recyclability of catalyst were also discussed. The results showed that MoO_3 can effectively convert phenol to benzene with 98.1% and 99.5% selectivity of benzene under optimal conditions(340 ℃, p_(H_2) =0.5 MPa,p_(N_2)=3 MPa).And the oxygen deficiency of MoO_3 was deemed to be the active center in the hydrodeoxygenation of phenol, which accounts for the hydrolysis of C_(AR)——OH to benzene. In addition, MoO_3 exhibited excellent recyclability. The catalytic activity remains at the same high level when the catalyst was repeatedly used for three times in the HDO of phenol,suggesting an excellent stability.
MoO_3 catalyst was prepared by calcination using(NH_4)_6 Mo_7 O_(24)·4 H_2 O as precursor and was characterized by XRD,XPS, H_2-TPR and low temperature N_2 adsorption. Aim to produce arene, hydrodeoxygenation(HDO) was carried out using phenol as model compound. The focus was the effects of reaction temperature, reaction time and reaction gas conposition on the phenol conversion rate and selectivity of target product. The catalytic mechanism of phenol HDO over MoO_3 and the recyclability of catalyst were also discussed. The results showed that MoO_3 can effectively convert phenol to benzene with 98.1% and 99.5% selectivity of benzene under optimal conditions(340 ℃, p_(H_2) =0.5 MPa,p_(N_2)=3 MPa).And the oxygen deficiency of MoO_3 was deemed to be the active center in the hydrodeoxygenation of phenol, which accounts for the hydrolysis of C_(AR)——OH to benzene. In addition, MoO_3 exhibited excellent recyclability. The catalytic activity remains at the same high level when the catalyst was repeatedly used for three times in the HDO of phenol,suggesting an excellent stability.
引文
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[25]李增文.煤焦油加氢工艺技术[J].化学工程师,2009,(10):57-61.[25]Li Zengwen.Hydrogenation technology of coal oil refining[J].Chemical Engineer,2009,(10):57-61.
[2]Long Jinxing,Lou Wenyong,Wang Lefu,et al.[C4H8SO3Hmim]HSO4as an efficient catalyst for direct liquefaction of bagasse lignin:Decomposition properties of the inner structural units[J].Chemical Engineering Science,2015,122:24-33.
[3]张兴华,陈伦刚,张琦,等.木质素基酚类化合物加氢脱氧制取碳氢燃料[J].化学进展,2014,26(12):1997-2006.[3]Zhang Xinghua,Chen Lungang,Zhang Qi,et al.Production of hydrocarbons via hydrodeoxugenation of lignin-derived phenolic compounds[J].Progress in Chemistry,2014,26(12):1997-2006.
[4]Badawi M,Paul J F,Cristol S,et al.Effect of water on the stability of Mo and CoMo hydrodeoxygenation catalysts:A combined experimental and DFT study[J].Journal of Catalysis,2011,282(1):155-164.
[5]Laurent E,Delmon B.influence of water in the deactivation of a sulfided nimo gamma-Al2O3catalyst during hydrodeoxygenation[J].Journal of Catalysis,1994,146(1):281-291.
[6]?enol O I?,Viljava T R,Krause A O I.Hydrodeoxygenation of methyl esters on sulphided NiMo/NiMo/γ-Al2O3and CoMo/γ-Al2O3catalysts[J].Catalysis Today,2005,100(3-4):331-335.
[7]Yang Yun,Gilbert A,Xu Chunbao(Charies).Hydrodeoxygenation of bio-crude in supercritical hexane with sulfided CoMo and CoMoP catalysts supported on MgO:A model compound study using phenol[J].Applied Catalysis A-General,2009,360(2):242-249.
[8]Ferrari M,Maggi R,Delmon B,et al.Influences of the hydrogen sulfide partial pressure and of a nitrogen compound on the hydrodeoxygenation activity of a CoMo/carbon catalyst[J].Journal of Catalysis,2001,198(1):47-55.
[9]Gutierrez A,Kaila R K,Honkela M L,et al.Hydrodeoxygenation of guaiacol on noble metal catalysts[J].Catalysis Today,2009,147(3-4):239-246.
[10]Zhao Chen,Kou Yuan,Lemonidou A A,et al.Highly selective catalytic conversion of phenolic bio-oil to alkanes[J].Angewandte Chemie-International Edition,2009,48(22):3987-3990.
[11]Li Chia-Liang,Lin Yu-Chuan.Catalytic partial oxidation of methanol over copper-zinc based catalysts:A comparative study of alumina,zirconia,and magnesia as promoters[J].Catalysis Letters,2010,140(1-2):69-76.
[12]Lee Cho Rin,Yoon Ji Sun,Suh Young-Woong,et al.Catalytic roles of metals and supports on hydrodeoxygenation of lignin monomer guaiacol[J].Catalysis Communications,2012,17:54-58.
[13]Rensel D J,Rouvimov S,Gina M E,et al.Highly selective bimetallic FeMoP catalyst for C-O bond cleavage of aryl ethers[J].Journal of Catalysis,2013,305:256-263.
[14]韩维屏.催化化学导论[M].北京:科学出版社,2003,350-354.[14]Han Weiping.Introduction to catalytic chemistry[M].Beijing:Science Press,2003,350-354.
[15]Prasomsri T,Nimmanwudipony T,Leshkov Y R.Effective hydrodeoxygenation of biomass-derived oxygenates into unsaturated hydrocarbons by MoO3using low H2pressures[J].Energy&Environmental Science,2013,6(6):1732-1738.
[16]Prasomsri T,Shetty M,Murugappan K,et al.Insights into the catalytic activity and surface modification of MoO3during the hydrodeoxygenation of lignin-derived model compounds into aromatic hydrocarbons under low hydrogen pressures[J].Energy&Environmental Science,2014,7(8):2660-2669.
[17]Shetty M,Prasomsri T,Murugappan K,et al.Reactivity and stability investigation of supported molybdenum oxide catalysts for the hydrodeoxygenation(HDO)of m-cresol[J].Journal of Catalysis,2015,331:86-97.
[18]Matsuda T,Hirata Y,Uchijima F,et al.Characteristics of MoO3reduced with H2at the different flow rates of H2[J].Bulletin of the Chemical Society of Japan,2000,73(4):1029-1034.
[19]Aigler J,Houalla M,Hercules D.Surface structure and metathesis activity of photoreduced allyl-based Mo/SiO2catalysts[J].Topics in Catalysis,2000,10(1-2):123-126.
[20]Ilangovan G,Pillai K.Electrochemical and XPScharacterization of glassy carbon electrode surface effects on the preparation of a monomeric molybdate(VI)-modified electrode[J].Langmuir,1997,13(3):566-575.
[21]Chary K V R,Reddy K R,Kishan G,et al.Structure and catalytic properties of molybdenum oxide catalysts supported on zirconia[J].Journal of Catalysis,2004,226(2):283-291.
[22]Bhaskar T,Reddy K R,Kumar C P,et al.Characterization and reactivity of molybdenum oxide catalysts supported on zirconia[J].Applied Catalysis A-General,2001,211(2):189-201.
[23]Ressler T,Jentoft R E,Wienold J J.In situ XAS and XRD studies on the formation of Mo suboxides during reduction of MoO3[J].Journal of Physical Chemistry B,2000,104(27):6360-6370.
[24]Moberg D R,Thibodeau T J,Amar F G,et al.Mechanism of hydrodeoxygenation of acrolein on a cluster model of MoO3[J].Journal of Physical Chemistry C,2010,114(32):13782-13795.
[25]李增文.煤焦油加氢工艺技术[J].化学工程师,2009,(10):57-61.[25]Li Zengwen.Hydrogenation technology of coal oil refining[J].Chemical Engineer,2009,(10):57-61.