蒸汽相法辅助碳模板合成介孔EU-1分子筛
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摘要
将蔗糖、硅源与铝源混合成凝胶,在170℃下部分碳化(MI)或者在无氧环境下400℃高温碳化(MII)两种方法原位制备碳硅铝复合物,然后采用蒸汽相法辅助合成多级孔EU-1分子筛。研究表明:MI、MII均可以有效提高样品的外表面积和介孔孔容,且当m(蔗糖)/m(SiO_2)为定值时,MII的介孔化能力优于MI.MI、MII合成的样品保持一致的规律,即随着m(蔗糖)/m(SiO_2)的增多,样品的结晶度逐渐降低,外表面积和介孔孔容逐渐增大,酸量明显减小。多级孔EU-1分子筛有利于扩散,有利于提高分子筛的二甲苯异构化催化性能,其催化活性从22.99%提升到23.92%,C8芳烃选择性从89.52%提升到91.12%.
The synthetic gel was prepared by mixing sucrose,silicon and aluminum,and then partially carbonized at 170 ℃ in air(MI)or carbonized at 400 ℃ in oxygen-free environment(MII)to obtain carbon-silicon-aluminum compound.The vapor phase method was adopted to synthesize hierarchical EU-1 zeolite.The research results showed that MI and MII can effectively improve the surface area and the pore volume of mesopores.When the m(sucrose)/m(SiO_2)was a fixed value,the mesoporous capacity of MII was better than that of MI.The synthetic samples by MI and MII maintain a consistent rule:with m(sucrose)/m(SiO_2)increasing,the crystallinity of the samples decreases gradually;the surface area and pore volume increase little by little;the amount of weak acid and strong acid decreases obviously.The hierarchical EU-1 zeolite is favorable for the diffusion and improved catalytic performance for xylene isomerization,with the catalytic activity increasing from 22.99% to 23.92%,C8 aromatic hydrocarbon selectivity increasing from 89.52% to 91.12%.
The synthetic gel was prepared by mixing sucrose,silicon and aluminum,and then partially carbonized at 170 ℃ in air(MI)or carbonized at 400 ℃ in oxygen-free environment(MII)to obtain carbon-silicon-aluminum compound.The vapor phase method was adopted to synthesize hierarchical EU-1 zeolite.The research results showed that MI and MII can effectively improve the surface area and the pore volume of mesopores.When the m(sucrose)/m(SiO_2)was a fixed value,the mesoporous capacity of MII was better than that of MI.The synthetic samples by MI and MII maintain a consistent rule:with m(sucrose)/m(SiO_2)increasing,the crystallinity of the samples decreases gradually;the surface area and pore volume increase little by little;the amount of weak acid and strong acid decreases obviously.The hierarchical EU-1 zeolite is favorable for the diffusion and improved catalytic performance for xylene isomerization,with the catalytic activity increasing from 22.99% to 23.92%,C8 aromatic hydrocarbon selectivity increasing from 89.52% to 91.12%.
引文
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[26]张磊,秦玉才,祖运,等.淀粉合成多级孔Y型分子筛及其吸附脱硫性能[J].石化技术与应用,2015(3):228-231.ZHANG L,QIN Y C,ZU Y,et al.Hierarchical porous zeolite Y synthesized with starch co-template and its performance of adsorptive desulfurization[J].Petrochemical Technology&Application,2015(3):228-231.
[2]CORMA A.From microporous to mesoporous molecular sieve materials and their use in catalysis[J].Chemical Reviews,1997,97(6):2373-2420.
[3]YANG P D,ZHAO D Y,MARGOLESE D I,et al.Generalized syntheses of large-pore mesoporous metal oxides with semicrystalline frameworks[J].Nature,1998,396(6707):152-155.
[4]CASCI J L,LOWE B M,WHITTAM T V.Zeolite EU-1:EP0042226[P].1981.
[5]SHARMA S B,GUREVICH S V,RILEY B D,et al.Selective xylenes isomerization and ethylbenzene conversion:US6143941[P].2000-11-07.
[6]CASCI J L,LOWE B M,WHITTAM T V.Catalytic isomerisation process employing zeolite EU-1:US4593138[P].1986.
[7]ALARIO F,JOLY J F,MAGNE-DRISCH J,et al.Process for isomerizing aromatic cuts containing eight carbon atoms using a catalyst containing a zeolite with an EUO type structure:US6337427[P].2002-01-08.
[8]ROULEAU L,LACOMBE S,ALARIO F,et al.Reacting aqueous mixture of sources of elements that form zeolite and monoamine precursor of alkylated polymethylene.alpha.-.omega.diammonium derivative to form zeolite:US6337063[P].2002-01-08.
[9]MOREAU F,MOREAU P,GNEP N S,et al.Ethylbenzene isomerization over bifunctional platinum alumina-EUO catalysts:location of the active sites[J].Microporous and Mesoporous Materials,2006,90(1):327-338.
[10]GUILLON E,SANCHEZ E.Modified EU-1zeolite and its use in the isomerization of aromatic C8compounds:US7838456[P].2010.
[11]ABREVAYA H.Cracking of naphtha range alkanes and naphthenes over zeolites[J].Studies in Surface Science and Catalysis,2007,170:1244-1251.
[12]ABREVAYA H,ABDO S F,PATTON R L.Enhancing production of light olefins using a catalyst with small pores,molecular sieve with high silica to alumina ratio and pores sizes to limit production of aromatics in the cracking process:US6867341[P].2005-03-15.
[13]CORMA A,REY F,RIUS J,et al.Supramolecular self-assembled molecules as organic directing agent for synthesis of zeolites[J].Nature,2004,431(7006):287-290.
[14]AHMED M H,MURAZA O,AL-AMER A M,et al.Development of hierarchical EU-1zeolite by sequential alkaline and acid treatments for selective dimethyl ether to propylene(DTP)[J].Applied Catalysis A General,2015,497:127-134.
[15]GROEN J C,MOULIJN J A.Alkaline posttreatment of MFI zeolites.From accelerated screening to scale-up[J].Industrial&Engineering Chemistry Research,2007,46(12):4193-4201.
[16]OGURA M,SHINOMIYA S,TATENO J,et al.Formation of uniform mesopores in ZSM-5zeolite through treatment in alkaline solution[J].Chemistry Letters,2000,29(8):882-887.
[17]CARTLIDGE S,NISSEN H U,WESSICKEN R.Ternarymesoporous structure of ultrastable zeolite CSZ-1[J].Zeolites,1989,9(4):346-351.
[18]EGEBLAD K,CHRISTENSEN C H,KUSTOVA M,et al.Templating mesoporous zeolites[J].Chemistry of Materials,2008,20(3):946-960.
[19]TAO Y S,HIROFUMI K,LLOYD A,et al.Mesopore-modified zeolites:preparation,characterization,and applications[J].Chem Rev,2006,106(3):896-910.
[20]TAO Y S,HIROFUMI K,KATSUMI K.ZSM-5monolith of uniform mesoporous channels[J].J Am Chem Soc,2003,125(20):6044-6045.
[21]KUSTOVA M,EGEBLAD K,ZHU K,et al.Versatile route to zeolite single crystals with controlled mesoporosity:in situ sugar decomposition for templating of hierarchical zeolites[J].Chemistry of Materials,2007,19(12):2915-2917.
[22]WANG W H,LI G,LI W G,et al.Synthesis of hierarchical TS-1by caramel templating[J].Chemical Communications,2011,47(12):3529-3531.
[23]NANDAN D,SAXENA S K,VISWANADHAM N.Synthesis of hierarchical ZSM-5using glucose as a templating precursor[J].Journal of Materials Chemistry,2013,2(4):1054-1059.
[24]徐会青,杜丽君,刘全杰,等.几种分子筛催化剂的二甲苯异构化反应性能研究[J].石油炼制与化工,2012,11:55-58.XU H Q,DU L J,LIU Q J,et al.Study on xylene isomerization of several molecular sieve catalysts[J].Petroleum Processing and Petrochemicals,2012,11:55-58.
[25]王晓星.多级孔TS-1沸石的合成、表征及催化性能研究[D].大连:大连理工大学,2011.WANG X X.Synthesis,characterization and catalytic performance of hierarchical TS-1zeolite[D].Dalian:Dalian University of Technology,2011.
[26]张磊,秦玉才,祖运,等.淀粉合成多级孔Y型分子筛及其吸附脱硫性能[J].石化技术与应用,2015(3):228-231.ZHANG L,QIN Y C,ZU Y,et al.Hierarchical porous zeolite Y synthesized with starch co-template and its performance of adsorptive desulfurization[J].Petrochemical Technology&Application,2015(3):228-231.