摘要
以粗孔硅胶为硅源,偏铝酸钠为铝源,四乙基氢氧化铵(TEAOH)为模板剂,采用微波加热法制备了小晶粒Beta分子筛,考察了晶化体系水含量、模板剂含量、晶化温度、晶化时间对Beta分子筛晶化的影响,并采用X射线衍射谱、N2物理吸附(BET)、扫描电子显微镜等方式对其晶型、晶体形貌、孔道结构等进行了表征。结果表明:当反应体系水硅摩尔比H2O/Si O2为3～4,模板剂与硅摩尔比TEA+/SiO2为0.13～0.15时,在160℃微波加热晶化10h,产品Beta分子筛相对结晶度可达138%,与常规水热合成方法相当,晶粒尺寸平均约为50 nm且分布非常集中。
Zeolite Beta was synthesized by microwave heating using silica gel as silicon source, sodium aluminate as aluminum source and tetraethylammonium hydroxide(TEAOH) as template. The structure and composition of the zeolite were characterized by X-ray diffraction, scanning electron microscope, N2 physical adsorption(BET). The results demonstrate that zeolite beta with similar crystallinity that synthesized under hydrothermal conditions was obtained at 160 ℃ for 10 h by microwave heating when the water-silica molar ratio of reaction system was quite low(H2O/Si O2=3-4), the appropriate template-silica molar ratio was between 0.13-0.15, the relative crystallinity of the product could reach 136, the average crystal size was 50 nm and was distribute intensively.
引文
[1]WADLINGER R L,KERR G T,ROSINSKI E J.Catalytic composition of a crystalline zeolite[P].US Patent,3308069.1976-03?07.
[2]RUBIN M K.Preparation of zeolite beta[P].Europe Patent,0159846.1985?10?30.
[3]RUBIN M K.Preparation of zeolite beta[P].Europe Patent,0159847.1985?10?30.
[4]BONETTO L,CAMBLOR M A,CORMA A,et al.Optimization of zeolite-βin cracking catalysts influence of crystallite size[J].Appl Catal A:General,1992,82(1):37?50.
[5]SAKTHIVEL A,IIDA A,KOMURA K,et al.Nanosizedβ-zeolites with tunable particle sizes:Synthesisby the dry gel conversion(DGC)method in thepresence of surfactants,characterization and catalyticproperties[J].Micropor Mesopor Mater,2009,119:322?330.
[6]CHEN S,YANG Y R,ZHANGK X,et al.BETA zeolitemade from mesoporous material and its hydrocracking performance[J].Catal Today,2006,116(1):2?5.
[7]BLOMSM E,MARTENS J A,JACOBS P A.Mechanisms of heptaneisomerization on bifunctional Pd/H-beta zeolites[J].J Catal,1996,159(2):323?331.
[8]LIUY F,ZHOU Y,JIANG H,et al.Deactivation mechanism of beta-zeolite catalyst for synthesis of cumene by benzene alkylation with sopropanol[J].Chin J Chem Eng,2017,25(9):1195?1201.
[9]ZHOU Y,JIANG H,LIU Y F,et al.Highly efficient synthesis of cumene via benzene isopropylation over nano-sized beta zeolite in a submerged ceramic membrane reactor[J].Sep Purif Technol,2016,170:49?56.
[10]XU L,SHI C,ZHANG Z S.Enhancement of low-temperature activity over Cu-exchanged zeolite beta from organotemplate-free synthesis for the selective catalytic reduction of NOx with NH3 in exhaust gas streams[J].Micropor Mesopor Mater,2014,200:304?310.
[11]XIA Y,ZHAN W C,GUO Y,et al.Fe-beta zeolite for selective catalytic reduction of NOx with NH3:Influence of Fe content[J].Chin J Catal,2016,37(12):2069?2078.
[12]XIE B,SONG J,REN L,et al.Organotemplate-free and fast route for synthesizing beta zeolite[J].Chem Mater,2008,20(14):4533?4535.
[13]WU Q M,WANG X,QI G D,et al.Sustainable synthesis of zeolites without addition of both organotemplates and solvents[J].J Am Chem Soc,2014,136(10):4019?4025.
[14]CONNER W C,TOMPSETT G,LEE K H,et al.Microwave synthesis of zeolites:?1.Reactor engineering[J].J Phys Chem B,2004,108(37):13913?13920.
[15]CHEN X X,YAN W F,GAO X J,et al.Fabrication of silicalite-1crystals with tunable aspect ratios by microwave-assisted solvothermal synthesis[J].Micropor Mesopor Mater,2009,119(1/3):217?222.
[16]MURAZA O,BAKARE I A,TAGO T,et al.Controlled and rapid growth of MTT zeolite crystals with low-aspect-ratio in a microwave reactor[J].Chem Eng J,2013,226:367?376.
[17]杨杰,吴伟,周亚静,等.SAPO-31分子筛的微波加热合成、表征及催化性能[J].催化学报,2011,32(7):1234?1241.YANG J,WU W,ZHOU Y J,et al.Chin J Catal(in Chinese),2011,32(7):1234?1241.
[18]许磊,王公慰,魏迎旭,等.MCM-41介孔分子筛合成研究[J].催化学报,1999,20(3):251?255.XU L,WANG G W,WEI Y X,et al.Chin J Catal(in Chinese),2009,20(3):251?255.
[19]SLANGEN P M,JANSEN J C,VAN BEKKUM H.The effect of ageing on the microwave synthesis of zeolite NaA[J].Micropor Mater,1997,9(5-6):259?265.
[20]CHANDRASEKHAR S,PRAMADA P N.Microwave assited synthesis of zeolite A from metakaolin[J].Micropor Mesopor Mater,2008,108:152?161.
[21]FANG Y T,HU Y H,LIANG X H,et al.Microwave hydrothermal synthesis and performance of NaA zeolite monolithic adsorbent with honeycomb ceramic matrix[J].Micropor Mesopor Mater,2018,259:116?122.
[22]KATSUKI H,FURUTA S.Microwave versus conventionalhydrothermal synthesis of NaY zeolite[J].J Porous Mater,2001,8(1):5?12.
[23]KOO J B,JIANG N Z,SARAVANAMURUGAN S,et al.Direct synthesis of carbon-templating mesoporous ZSM-5 using microwave heating[J].J Catal,2010,276(2):327?334.
[24]SAKTHIVEL A,LIDA A,KOMURA K,et al.Nanosizedβ-zeolites with tunable particle sizes:Synthesis by the dry gel conversion(DGC)method in the presence of surfactants,characterization and catalytic properties[J].Micropor Mesopor Mater,2009,119(1-3):322?330.
[25]ZHAO J P,CUNDY C,DWYER J.Synthesis of zeolitesin a microwave heating environment[J].Stud Surf Sci Catal,1997,105(97):181?187.
[26]KIM D S,CHANG J S,HWANG J S,et al.Synthesis of zeolite beta in fluoride media under microwaveirradiation[J].Micropor Mesopor Mater,2004,68(1/3):77?82.
[27]MURAZA O,ABDUL-LATEEF A,TAGO T,et al.Microwaveassisted hydrothermal synthesis of submicron ZSM-22 zeolites and their applications in light olefin production[J].Micropor Mesopor Mater,2015,206:136?143.
[28]JURY F A,POLAERT I,ESTEL L,et al.Enhancement of synthesis of ZSM-11 zeolite by microwave irradiation[J].Micropor Mesopor Mater,2014,198:22?28.
[29]FUKASAWA T,HORIGOME A,KARISMA A D,et al.Utilization of incineration fly ash from biomass power plants for zeolite synthesis from coal fly by microwave hydrothermal treatment[J].Adv Powder Technol,2018,29(3):450?456.
[30]BAI L,NAN G Z,WANG Y H,et al.Ultrafast microwave synthesis of all-silica DDR zeilite[J].Micropor Mesopor Mater,2016,228:54?58.
[31]BOURGEAT-LAMI E,DI RENZO F,FAJULA F,et al.Mechanism of the thermal decomposition of tetraethylammonium in zeolite[J].J Phys Chem,1992,96(9):3807?3811.
[32]孔德金,邢宇,陈波,等.抑制β沸石骨架脱铝的焙烧研究[J].化学物理学报,2002,15(2):127?131.KONG D J,XING Y,CHEN B,et al.Chin J Chem Phys(in Chinese),2002,15(2):127?131.
