氧化锆催化合成气直接转化制芳烃
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摘要
采用共沉淀法和水热法制备了三种不同粒径、不同结构的纳米氧化锆催化剂,借助XRD、TEM、Raman光谱、N_2物理吸附、XPS、NH_3-TPD表征了催化剂的物理化学性质,并研究了其合成气催化转化性能。在400℃、3 M Pa、空速500 m L/(gcat·h)、进料组成H_2/CO/Ar(体积比)为5∶5∶1时,氧化锆能够一步催化合成气转化为高辛烷值烃类产物,主要是异构烯烃、环状烯烃及芳烃。在烃类产物中,C_(5+)选择性高达48%,C_(5+)中芳烃含量为30%-53%。结果表明,单斜相氧化锆比四方相更有利于CO转化,其中,比表面积较大、酸量较大的小粒径氧化锆表现出最高的CO转化率及产物收率;而大晶粒单斜相氧化锆表现出最高的芳烃选择性,这与其较高的酸性位密度相对应。因此,CO转化在Zr O_2催化剂上是酸催化反应,酸量影响催化剂的活性,而酸性位密度是影响芳烃等较大分子量产物生成的主要因素。
A series of ZrO_2 nanoparticles with different particle sizes and different crystalline phases were prepared using coprecipitation and hydrothermal methods. Their physico-chemical properties were characterized by N2 physisorption,XRD, TEM,Raman spectroscopy,XPS, and NH_3-TPD techniques. The catalytic performances for syngas conversion were tested at 400 ℃,3 MPa,gas hourly space velocity( GHSV) of500 mL /( gcat·h),and H_2 /CO /Ar( volume ratio) = 5 ∶5 ∶1. It was found that syngas can be directly converted into hydrocarbons over ZrO_2 nanoparticles. The hydrocarbon products are mainly composed of isomerized olefins,cyclenes,and aromatics. The selectivity of C5+ hydrocarbons is up to 48%. Moreover,the aromatic concentration in C5+ ranges from 30% to 53% depending on ZrO_2 structures. It is also found that the monoclinic ZrO_2 shows higher activity than the tetragonal one. Monoclinic ZrO_2 with larger specific surface area and acid amount show highest CO conversion as well as the yield of target products,but the monoclinic ZrO_2 with lager particle size has the higher acid surface density and results in the higher aromatic selectivity. Consequently,acidity is the key factor for CO conversion. And high acid surface density promotes the formation of aromatics but acid amount affects the activity.
A series of ZrO_2 nanoparticles with different particle sizes and different crystalline phases were prepared using coprecipitation and hydrothermal methods. Their physico-chemical properties were characterized by N2 physisorption,XRD, TEM,Raman spectroscopy,XPS, and NH_3-TPD techniques. The catalytic performances for syngas conversion were tested at 400 ℃,3 MPa,gas hourly space velocity( GHSV) of500 mL /( gcat·h),and H_2 /CO /Ar( volume ratio) = 5 ∶5 ∶1. It was found that syngas can be directly converted into hydrocarbons over ZrO_2 nanoparticles. The hydrocarbon products are mainly composed of isomerized olefins,cyclenes,and aromatics. The selectivity of C5+ hydrocarbons is up to 48%. Moreover,the aromatic concentration in C5+ ranges from 30% to 53% depending on ZrO_2 structures. It is also found that the monoclinic ZrO_2 shows higher activity than the tetragonal one. Monoclinic ZrO_2 with larger specific surface area and acid amount show highest CO conversion as well as the yield of target products,but the monoclinic ZrO_2 with lager particle size has the higher acid surface density and results in the higher aromatic selectivity. Consequently,acidity is the key factor for CO conversion. And high acid surface density promotes the formation of aromatics but acid amount affects the activity.
引文
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[20]LI Y W,HE D H,CHENG Z X,SU C L,LI R J,ZHU Q M.Effect of calcium salts on isosynthesis over Zr O2catalysts[J].J M ol Catal A:Chem,2001,175(1/2):267-275.
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[22]ZHANG R J,HE D H.Effect of alcohol solvents treated Zr O(OH)2hydrogel on properties of Zr O2and its catalytic performance in isosynthesis[J].J Nat Gas Chem,2012,21(1):1-6.
[23]MARUYA K,KOMIYA T,HAYAKAWA T,LU L H,YASHIMA M.Active sites on Zr O2for the formation of isobutene from CO and H2[J].J Mol Catal A:Chem,2000,159(1):97-102.
[24]ZHANG R,LIU H,HE D.Pure monoclinic Zr O2prepared by hydrothermal method for isosynthesis[J].Catal Commun,2012,26:244-247.
[25]CHANG C D,LANG W H,SILVESTRI A J.Synthesis gas conversion to aromatic-hydrocarbon[J].J Catal,1979,56(2):268-273.
[26]LI W Z,HUANG H,LI H J,ZHANG W,LIU H C.Facile synthesis of pure monoclinic and tetragonal zirconia nanoparticles and their phase effects on the behavior of supported molybdena catalysts for methanol-selective oxidation[J].Langmuir,2008,24(15):8358-8366.
[27]李为臻,刘海超.溶剂热法合成纯单斜和四方晶相氧化锆中的溶剂效应[J].物理化学学报,2008,24(12):2172-2178.(LI Wei-zhen,LIU Hai-chao.Solvent effects on the solvothermal synthesis of pure monoclinic and tetragonal zirconia nanoparticles[J].Acta Phys-Chim Sin,2008,24(12):2172-2178.)
[28]李美俊,冯兆池,张静,应品良,辛勤,李灿.紫外拉曼光谱研究焙烧气氛对氧化锆相变的影响[J].催化学报,2003,11:861-866.(LI Mei-jun,FENG Zhao-chi,ZHANG Jing,YING Pin-liang,XIN qin,LI Can.Study of influence of calcination atmosphere on phase transformation of zirconia by UV raman spectroscopy[J].Chin J Catal,2003,11:861-866.)
[29]ZHANG W,TAN Y Y,GAO Y L,WU J X,TANG B.Ultrafine nano zirconia as electrochemical pseudocapacitor material[J].Ceram Int,2015,41(2):2626-2630.
[30]ARDIZZONE S,BIANCHI C L.XPS characterization of sulphated zirconia catalysts:The role of iron[J].Surf Interface Anal,2000,30(1):77-80.
[2]SARTIPI S,ALBERTS M,SANTOS V P,NASALEVICH M,GASCON J,KAPTEIJN F.Insights into the catalytic performance of mesoporous HZSM-5-supported cobalt in Fischer-Tropsch synthesis[J].Chem Cat Chem,2014,6(1):142-151.
[3]DE SMIT E,WECKHUYSEN B M.The renaissance of iron-based Fischer-Tropsch synthesis:on the multifaceted catalyst deactivation behaviour[J].Chem Soc Rev,2008,37(12):2758-2781.
[4]DRY M E.Fischer-Tropsch reactions and the environment[J].Appl Catal A:Gen,1999,189(2):185-190.
[5]ANDERSON R B.Catalysts for the Fischer-Tropsch synthesis[C].New York:Van Nostrand Reinhold,1956.
[6]UDAYA V,RAO S,GORMLEY R J.Bifunctional catalysis in syngas conversions[J].Catal Today,1990,6(3):207-234.
[7]VAN Der LAAN G P,BEENACKERS A.Kinetics and selectivity of the Fischer-Tropsch synthesis:A literature review[J].Catal Rev,1999,41(3/4):255-318.
[8]相宏伟,杨勇,李永旺.煤炭间接液化:从基础到工业化[J].中国科学:化学,2014,12:1876-1892.(XIANG Hong-wei,YANG Yong,LI Yong-wang.Indirect coal liquefaction:from base to industrialization[J].Sci China Chem,2014,12:1876-1892.)
[9]SUN B,QIAO M H,FAN K N A,ULRICH J,TAO F.Fischer-Tropsch synthesis over molecular sieve supported catalysts[J].Chem Cat Chem,2011,3(3):542-550.
[10]TOEMEN S,ABU BAKAR W A W,ALI R.Investigation of Ru/Mn/Ce/Al2O3catalyst for carbon dioxide methanation:Catalytic optimization,physicochemical studies and RSM[J].J Taiwan Inst Chem E,2014,45(5):2370-2378.
[11]FAN J,WENG D,WU X D,RAN R.Modification of Ce O2-Zr O2mixed oxides by coprecipitated/impregnated Sr:Effect on the microstructure and oxygen storage capacity[J].J Catal,2008,258(1):177-186.
[12]GE S,HE D,LI Z.A mesoporous Ce0.5Zr0.5O2solid solution catalyst for CO hydrogenation to iso-C4hydrocarbons[J].Catal Lett,2008,126(1/2):193-199.
[13]ZHU Z,HE D.CO hydrogenation to iso-C4hydrocarbons over Ce O2-Ti O2catalysts[J].Fuel,2008,87(10/11):2229-2235.
[14]PICHLER H,ZIESECKE K H.Isosynthesis by reduced oxide catalysts[J].Brennst Chem,1949,30:13-80.
[15]MAEHASHI T,MARUYA K,DOMEN K,AIKA K,ONISHI T.Selective formation of iso-butene from carbon-monoxide and hydrogen over zirconium-oxide catalyst[J].Chem Lett,1984,5:747-748.
[16]MARUYA K,MAEHASHI T,HARAOKA T,NARUI S,ASAKAWA Y,DOMEN K,ONISHI T.The CO-H2reaction over Zr O2to form isobutene selectively[J].Bull Chem Soc Jpn,1988,61(3):667-671.
[17]NANCY B.JACKSON J G E.The surface characteristics required for isosynthesis over zirconium dioxide and modified zirconium dioxide[J].J Catal,1990,126(1):31-45.
[18]SU C L,HE D H,LI J R,CHEN Z X,ZHU Q M.Synthesis of isobutene from synthesis gas over nanosize zirconia catalysts[J].Appl Catal A:Gen,2000,202(1):81-89.
[19]LI Y W,HE D H,YUAN Y B,CHEN Z X,ZHU Q M.Selective formation of isobutene from CO hydrogenation over zirconium dioxide based catalysts[J].Energy Fuels,2001,15(6):1434-1440.
[20]LI Y W,HE D H,CHENG Z X,SU C L,LI R J,ZHU Q M.Effect of calcium salts on isosynthesis over Zr O2catalysts[J].J M ol Catal A:Chem,2001,175(1/2):267-275.
[21]LI Y W,HE D H,ZHU Q M,ZHANG X,XU B Q.Effects of redox properties and acid-base properties on isosynthesis over Zr O2-based catalysts[J].J Catal,2004,221(2):584-593.
[22]ZHANG R J,HE D H.Effect of alcohol solvents treated Zr O(OH)2hydrogel on properties of Zr O2and its catalytic performance in isosynthesis[J].J Nat Gas Chem,2012,21(1):1-6.
[23]MARUYA K,KOMIYA T,HAYAKAWA T,LU L H,YASHIMA M.Active sites on Zr O2for the formation of isobutene from CO and H2[J].J Mol Catal A:Chem,2000,159(1):97-102.
[24]ZHANG R,LIU H,HE D.Pure monoclinic Zr O2prepared by hydrothermal method for isosynthesis[J].Catal Commun,2012,26:244-247.
[25]CHANG C D,LANG W H,SILVESTRI A J.Synthesis gas conversion to aromatic-hydrocarbon[J].J Catal,1979,56(2):268-273.
[26]LI W Z,HUANG H,LI H J,ZHANG W,LIU H C.Facile synthesis of pure monoclinic and tetragonal zirconia nanoparticles and their phase effects on the behavior of supported molybdena catalysts for methanol-selective oxidation[J].Langmuir,2008,24(15):8358-8366.
[27]李为臻,刘海超.溶剂热法合成纯单斜和四方晶相氧化锆中的溶剂效应[J].物理化学学报,2008,24(12):2172-2178.(LI Wei-zhen,LIU Hai-chao.Solvent effects on the solvothermal synthesis of pure monoclinic and tetragonal zirconia nanoparticles[J].Acta Phys-Chim Sin,2008,24(12):2172-2178.)
[28]李美俊,冯兆池,张静,应品良,辛勤,李灿.紫外拉曼光谱研究焙烧气氛对氧化锆相变的影响[J].催化学报,2003,11:861-866.(LI Mei-jun,FENG Zhao-chi,ZHANG Jing,YING Pin-liang,XIN qin,LI Can.Study of influence of calcination atmosphere on phase transformation of zirconia by UV raman spectroscopy[J].Chin J Catal,2003,11:861-866.)
[29]ZHANG W,TAN Y Y,GAO Y L,WU J X,TANG B.Ultrafine nano zirconia as electrochemical pseudocapacitor material[J].Ceram Int,2015,41(2):2626-2630.
[30]ARDIZZONE S,BIANCHI C L.XPS characterization of sulphated zirconia catalysts:The role of iron[J].Surf Interface Anal,2000,30(1):77-80.