摘要
2,6-二甲基萘(2,6-DMN)是合成高性能聚酯材料的重要中间体,目前倍受关注。沸石催化2-甲基萘(2-MN)与甲醇烷基化合成2,6-DMN具有工艺路线短、原料来源广、价格便宜等优点,是一种具有开发潜力的工艺路线。本论文以获得高活性、高稳定性、高2,6-DMN选择性和收率以及2,6-/2,7-DMN比为目标,考察了以MFI系列中,HZSM-5催化剂的制备、改性过程中引入介孔和杂原子对催化效果的影响。
对硅铝比为65的微米级HZSM-5进行碱处理脱硅,之后进行Zr同晶取代,并与硅铝比为28纳米沸石进行比较。发现尽管所使用的纳米ZSM-5催化剂有着较低的硅铝比和较小的颗粒尺寸,但其催化活性却没有碱处理后的微米ZSM-5催化剂高,由N_2吸附等温线和XRF可知,碱处理脱硅产生了介孔,能够有效地降低反应物在沸石孔道中的扩散阻力,更容易接近活性位从而提高2-MN的转化率。另外,介孔也容易使结炭前驱体扩散出孔道,从而使催化剂寿命得到提高。
以硅铝比为28的纳米级HZSM-5进行碱处理脱硅,随后进行Zr同晶取代,考察在纳米级沸石上引入介孔和杂原子改性对催化效果的影响。发现经过碱处理之后,催化剂的活性和寿命的都得到提高,分析其原因为,在碱处理脱硅过程中产生了介孔,增大了反应物和产物在沸石孔道中的扩散性,既有利于反应物接触到催化活性位,又有利于产物扩散出孔道,抑制了结炭前驱体的生成。我们在对纳米ZSM-5以0.025 mol/L的NaOH溶液处理4 h,并以Zr/Al比为0.5的(NH_4)_2ZrF_6进行改性所得的MFI沸石为催化剂进行烷基化反应,在反应进行0.75 h,得到最高9.9%的2,6-DMN收率。
以炭气凝胶为硬模板合成多级孔道Fe-MFI沸石,并考察不同含量炭气凝胶对合成的沸石介孔孔容的影响。我们发现,由于炭气凝胶加入所产生的介孔同样有助于沸石催化剂活性和寿命的提高。
Selective synthesis of 2,6-dimethylnaphthalene(2,6-DMN),a preferred intermediate of high performance polymeric materials,has been widely studied.Methylation of 2-methylnaphthalene(2-MN) with methanol is a more promising route to produce 2,6-DMN owing to the simple technologic process,cheap and wide source of raw materials.In this work, we investigatived the effect of preparation,introduce mesoporous and extra-atom into HZSM-5 by modificating to the catalyst reaction,and try to get the catalysts with high activitation and stability,high 2,6-/2,7-DMN ratio and high 2,6-DMN selectivity and yield.
The micrometer-scale HZSM-5 with a 65 SiO_2/Al_2O_3 was selected as parent catalyst to be alkali-treated by NaOH solution,and to be modified with(NH_4)_2ZrF_6,the samples were compared the nano-scale HZSM-5.It shows that,the catalyst activity of nano-scale HZSM-5 is lower than the alkali-treated micrometer-scale HZSM-5,although,it has a lower ratio of SiO_2/Al_2O_3 and a smaller crystal-scale.The Nitrogen adsorption isotherms and the XRF show that it is the step of alkali-treatment had introduced some mesoporous into micrometer-scale HZSM-5 by desilication reaction.The mesoporous reduced the resistence of reactants diffusing to catalyst active sites,and the mesoporous made the coking percusor more easliy left catalyst,the lifetime of catalyst improved.
The nano-scale HZSM-5 with a 28 SiO_2/Al_2O_3 was selected as parent catalyst to be alkali-treated by NaOH solution,and modified with(NH_4)_2ZrF_6,the effect of the introducing of mesoporous and modified by Zr on methylation reaction was investagated.We found that the activity and life of catalyst were both improved.We considered that the mesoporous had the reactants and reaction products easily diffusing in and out pores,both reactants proned to reach the active sites and reaction products slope off the zeolite internal.When we used the sample prepared by 0.025 mol/L NaOH solution treated for 4 h and then modified by (NH_4)_2ZrF_6 solution with a 0.5 Zr /Al to be modified for 10 h as catalyst to perform the methylation reaction.We got a 9.9%yield of 2,6-DMN when the reaction carried on for 0.75 h.
Carbon aerogel as hard template was used to synthesize Fe-MFI zeolite which has some mesoporous,and the effect of carbon aerogel content on the pore volume.We found that the use of carbon aerogel is also helpful to improve the activity and lifetime of the zeolite catalyst.
引文
[1]GROEN J C,ZHU W D,BROUWER S,et al.Direct demonstration of enhanced diffusion in mesoporous ZSM-5 zeolite obtained via controlled desilication[J].J.Am.Chem.Soc.,2007,129:355-360.
[2]MCMAhON R F,GREENE J D,PTERSON D A.Process for preparing 2,6-naphthalenedicarboxylic acid[P].US,61145575.2000-09-05.
[3]MOTOYUKI M,YAMAMOTO K,SAPARE A V,et al.Process for preparing 2,6-dialkylnaphthalene[P].US,6018080.2000-01-25.
[4]宋厚春.聚酯行业发展及趋势[J].化工新型材料,2002,30:1.
[5]日本工业科学技术研究院资源和环境研究所.低成本的二甲基萘提纯法[J].石油化工,1997,26(8):575.
[63 TAKAGAWA M,et al.Process for preparing 2,6-dialkylnaphthalene[P].US,5948949.1999-09-07.
[7]许杰,赵小平,张利新.2,6-二甲基萘的制备与分离技术进展[J].石油化工动态,2000,8(6):37.
[8]白雪峰,吴伟,胡浩权.2,6-二甲基萘的制备方法[J].现代化工,2003(9):10-13.
[9]CHEN C Y,SCHINSKI W,O'REAR D,et al.Method of making dimethylnaphthalenes[P].US,5955641.1999-09-21.
[10]DEL ROSSI K J,GREEN L A,HUSS Jr A,et al.Process for preparing dimethylnaphthalene[P].US,5043501.1991-08-27.
[11]TAKAGAWA M,YAMAGISHI K,YOSHIHARA J,et al.Process for producing 2,6-dimethylnaphthalene[P].US,5068480.1991-11-26.
[12]INAMASA K,FUSHIMI N,TAKAGAWA M.Process for prodyucing 2,6-dimethylnaphthalene[P].US,5321178.1994-06-14.
[13]VAHTERISTO K,HALME E,KOSKIMIES S,et al.Manufacturing of 2,6-dimethylnaphthalene[P].US,59522534.1999-09-14.
[14]ABE T,EBATA S,MACHIDA H,et al.Process for production of 2,6-dimethylnaphthalene[P].US,5023390.1991-06-11.
[15]SIKKENGA D L,ZAENGER I C,WILLIMAS G S.Preparation of dimethyltetralin in a distillation reactor[P].US,5284987.1994-02-08.
[16]FRAENKEL D,CHERNIAVSKY M,ITTAH B,et al.Shape-selective alkylation of naphthalene and methylnaphthalene with methanol over HZSM-5 zeolite catalysts[J].J.Catal.,1986,101:273-83.
[17]PARK J N.Methylation of naphthalene with methanol over beta,mordenite,ZSM-12and MCM-22 zeolite catalysts[J].Bull.Korea Chem.Soc.,2002,23(7):1001-1006.
[18]WEIKAMP J,NENBER M.Shape selective reactions of alkylnaphthalenes in zeolite catalysts[J].Stud.Surf.Sci.Catal.,1991,60:291-301.
[19]栗同林,刘希尧,王祥生.H β-沸石的氧化物改性对由β-甲基萘选择合成2,6-二甲基萘反应的影响[J].催化学报,1998,9:181-183.
[20]KOMATSU I,ARAKI Y,NAMBA S,et al.Selective formation of 2,6-dimethylnaphthalene from 2-methylnaphthalene on ZSM-5 and metallosilicates with MFI structure[J].Stud.Surf.Sci.Catal.,1994,84:1821-1828.
[21]PUS B,INUI T.Synthesis of 2,6-dimethylnaphthalene by methylation of methylnaphthalene on various medium and large-pore zeolite catalysts[J].Appl.Catal.A.General.,1996,146:305-316.
[22]栗同林,刘希尧,王祥生.H β-沸石的氧化物改性对由β-甲基萘选择合成2,6-二甲基萘反应的影响[J].分子催化,1997,11(5):383-386.
[23]CHEN N Y,GARWOOD W.Synthesis,Characterization and catalysis properties of Nu-1,Fu-1 and realated zeolites[J].Cat.Rev.-Sci.Eng.,1985(3):461.
[24]ZHENG S,ANDERAS J,JOHANNES A L.On the enhanced para-selectivity of HZSM-5modified by antimony oxide[J].J.Catal.,2003,219:310-319.
[25]GYULA T,ISTVA P,ARPAD M,et al.Molecular shape,dimensions,and shape selective catalysis[J].J.Mol.Struct.,2003,666:69-77.
[26]KRESTENE,CHRISTIN H C,MARINA K,et al.Templating Mesoporous Zeolites[J].Chem.Mater.,2008,20:946-960.
[27]CHRISTENSEN C H,JOHAANNSEN K,TORNQVIST E,et al.Mesoporous zeolite single crystal catalysts:Diffusion and catalysis in hierarchical zeolites[J].Catalysis Today,2007,128:117-122.
[28]JACOBSEN C H,MADSEN C,HOUZVICKA J,et al.Mesoporous zeolite single crystals [J].J.Am.Chem.Soc.,2000,122:7116-7117.
[29]TAO Y S,KANOH H,ABRAMS L,et al.Mesopore-modified zeolites:preparation,characterization,and applications[J].Chem.Rev.,2006,106:896-910.
[30]WANG H,PINNAVAIA T J.MFI zeolite with small and uniform intracrystal mesopores [J].Angew.Chem.Int.Ed.,2006,45:7603-7606.
[31]方云明,多级孔道沸石分子筛的合成、表征及催化应用[D].大连:大连理工大学,2008.
[32]DREWS T O,TSAPATISIS M.Model of the evolution of nanoparticles to crystals via an aggregative growth mechanism[J].Microporous and Mesoporous Materials,2007,101:97-107.
[33]CHRISTENSEN C H,SCHMIDT I,et al.Improved performance of mesoporous zeolite single crystals in catalytic cracking and isomerization of n-hexadecane[J].Catalysis Communications,2004,5:543-546.
[34]WANG J,PARK J H,PARK Y K,et al.On the isopropylation of naphthalene over zeolite catalysts in the high-pressure fixed-bed flow reactor[J].Catalysis Today,2004,97:283 -289.
[35]JANSSEN A H,KOSTER A J,et al.On the shape of the mesopores in zeolite Y:A three-dimensional transmission electron microscopy study combined with texture analysis[J].J.Phys.Chem.B.,2002,106:11905-11909.
[36]RYOO R,JOO S H,KRUK M,et al.Ordered mesoporous carbons[J].Adv.Mater.,2001,13:677-681.
[37]JOO S H,CHOI S J,OH I,et al.Ordered nanoporous arrays of carbon supporting high dispersions of platinum nanoparticles[J].Nature,2001,412:169-172.
[38]CHOI M,SRIVASTAVA R,RYOO R.Organosilane surfactant-directed synthesis of mesoporous aluminophosphates constructed with crystalline microporous frameworks [J].Chem.Commun.,2006,4380- 4382.
[39]TSI G,MIZUKAMI F,PALNKO I,et al.Positional isomerization of dialkylnaphthalenes:A comprehensive interpretation of the selective formation of 2,6-DIPN over HM zeolite[J].J.Phys.Chem.A.,2001,105:6513-6518.
[40]RYOO R,JOO S H,JUN S J.Acidity and catalytic activity of mesoporous ZSM-5 in comparison with zeolite ZSM-5,Al-MCM-41 and silica-alumina[J].Phy.Chem.,1999,103:7743.
[41]闫欣,韩书华,侯万国.模板法合成六方介孔SiO2[J].应用化学,2004,9:21.
[42]SRIVASTAVA R,CHOI M,RYOO R.Mesoporous materials with zeolite framework:remarkable effect of the hierarchical structure for retardation of catalyst deactivation[J].Chem.Commun.,2006:4489-4491.
[43]LI H C,SAKAMOTO Y,LIU Z,et al.Mesoporous Silicalite-1 zeolite crystals with unique pore shapes analogous to the morphology[J].Microporous and Mesoporous Materials,2007,106:174-179.
[44]JONG-HO Kim,AKIHISA I,MANABU O,et al.Modification of HZSM-5 by CVD of various silicon compounds and generation of para-selectivity[J].Journal of Catalysis,1996,161:387-392.
[45]张敬畅,孙发群,曹维良.改性β沸石催化邻苯二酚叔丁基化反应[J].宁夏大学学报,2001,22(2):109-111.
[46]靳会杰,姚智辉,周海清等.MgO改性的HZSM-5酸性和催化作用[J].化学研究,2000,11(2):45-47.
[47]王珏,赵璧英,谢有畅.MgO/HZSM-5中MgO分散状态和催化性能的关系[J].物理化学学报,2001,17(11):966-971.
[48]曾海生,崔惠玲,单学蕾等.Al、Bi及P改性β分子筛的表面酸性及对烷基转移反应的影响[J].离子交换与吸附,1999,15(4):359-363.
[49]PARK J,WANG J,HONGS,LEE C W.Effect of dealumination of zeolite catalysts on methylation of 2-methylnaphthalene in a high-pressure fixed-bed reactor[J].Appl.Catal.A:General,2005,292:68-75.
[50]王旭艳,方云明,邱燕,胡浩权.氟化物改性的MCM-22沸石催化2-甲基萘甲醇烷基化反应[C].第二届全国化学工程与生物化工年会论文集.
[51]JIN L J,HUH Q,ZHUS W.Preparation of 2,6-DMN by methylation of 2-MN with methanol on Zr/ZSM-5[J].Div.Pet.Chem.,2004,49(3):371-373.
[52]JIN L J,HU H Q.Methylation of 2-methylnaphthalene with methanol to 2,6-dimethylnaphthalene over ZSM-5 modified by Zr and Si[J].Ind.Eng.Chem.Res.,2006,45(10):3531-3536.
[53]JIN L J,FANG Y M,HE H Q.Selectivity synthesis of synthesis of 2,6-dimethylnaphthalene by methylation of 2-methylnaphthalene on Zr/(Al)ZSM-5[J],Catal.Commun.,2006,7:255.
[54]FANG Y M,HUH Q,An ordered mesoporous aluminosilicate with completely crystaline zeolite structure[J].J.Am.Chem.Soc.,2006,128:10636-10637.
[55]薛华成.管理信息系统[M].北京:清华大学出版社,1993.
[56]SONG C S,LILLWITA J.Selective methylation catalyst,method of catalyst manufacture and methylation process[P].US,2005054889.2005.
[57]ZHANG C,GUO X W,WANG Y N,et al.Methylation of 2-methylnaphthalene with methanol to 2,6-dimethylnaphthalene over HZSM-5 modified by NH_4F and SrO[J],Catal.Commun.,2007,18:1281.
[58]SU L,LIU L,ZHUANG J,WANG H,et al.Post-steam-treatment of Mo/HZSM-5catalysts:An alternative and effective approach for enhancing their catalytic performances of methane dehydroaromatization[J].J.Phys.Chem.B.,2003,107:12964- 12972.
[59]JOHAN C G,TORKEL B,ULTIKE Z,et al.Creation of hollow zeolite architectures by controlled desilication of Al-Zoned ZSM-5 crystals[J].J.Am.Chem.Soc.,2005,127:10792 -10793.
[60]王岳,李凤艳,赵天波等.纳米ZSM-5分子筛的合成、表征及甲苯歧化催化性能[J].石油化工高等学校学报,2005,18(4):20.
[61]王亚军,唐颐.纳米沸石的合成、性质、组装及应用[J].石油化工,2002,31(3):217.
[62]JIN L J,HUH Q,WANG X Y,LIU C.Methylation of 2-methylnaphthalene with methanol to 2,6-dimethylnaphthalene over ZSM-5 modified by Zr and Si[J].Ind.Eng.Chem.Res.,2006,45(10):3531-3536.
[63]JIN L J,ZHOU X J,HU H Q,MAB.Synthesis of 2,6-dimethylnaphthalene by methylation of 2-methylnaphthalene on mesoporous ZSM-5 by desilication[J].Catal.Commun.,2008,10:336 - 340.
[64]HARTMANN M,KEVAN L.Transition-metal ions in molecular sieves[J].Chemical Reviews,1999,99(3):637.
[65]靳立军,二甲基萘与甲醇烷基化选择性合成2,6-二甲基萘研究[D].大连:大连理工大学,2006:51-52.
[66]RAKSHE B,RAMSWAMY V S,HEGDE G,VETRIVEL R,et al.Crystalline,microporous zirconium silicates with MFI structure.Catal.Lett.,1997,45:41-50.
[67]靳立军,二甲基萘与甲醇烷基化选择性合成2,6-二甲基萘研究[D].大连:大连理工大学,2006:94.
[68]CHOI M,CHO H S,SRIVASTAVA R,et al.Amphilphilic organosilane-directed synthesis of crystalline zeolite with tunable mesoporosity[J],Nature Materials,2006,5:718-723.
[69]CHRISTENSEN C H,JOHANNSEN K,SCHMIDT I.Catalytic benzene alkylation over mesoporous zeolite single crystals:Improving activity and selectivity with a new family of porous materials[J].J.Am.Chem.So.,2003,125:13370-13371.
[70]SCHMIDT I,KROGH A,WIENBERG K,et al.Catalyutic epoxidation of alkenes with hydrogen peroxide over first mesoporous titanium-cintaining zeolite[J].Chem.Commun.,2000,21:2157-2158.
[71]BURKETT S L,DARS M Z.Mechanism of structure direction in the synthesis of pure-silica zeolite 2:Hydrophobic hydration and structure specificity[J].Chem Mater.,1995,7:1455-1465.
[72]KUMAR R,MUKHERJEE P,PANDEY R K.Role of oxyansions as promoter for enhancing nucleation and crystallization in the synthesis of MFI-type microporous materials [J].Microporous and Mesoporous Materials,1998,22:23-31.
[73]朱玉东,炭气凝胶的制备及在超级电容器中的应用[D].大连:大连理工大学博士论文,2006:35-40.