212 (2015) 73--Seed-directed synthesis of EMT-type zeolite from an organic-template-free system

Seed-directed synthesis of EMT-type zeolite from anorganic-template-free systemQin Mou,Niu Li*,Shouhe XiangKey Laboratory of Advanced Energy Materials Chemistry,Ministry of Education,College of Chemistry,Nankai University,94Weijin Road, Tianjin300071,PR Chinaa r t i c l e i n f oArticle history:Received17December2014 Received in revised form17March2015Accepted23March2015 Available online1April2015Keywords:EMT zeoliteEMC-2Seed crystalsTemplate-free18-Crown-6ether a b s t r a c tEMT-type zeolite has been prepared by usage of seed directed method from an organic-template-free system(named as EMC-2-SOF).Powder X-ray diffraction(XRD)patterns verified that the diffraction patterns of EMC-2-SOF matched very well with EMC-2synthesized using18-crown-6ether as template. EMT-type zeolite with complete diffraction patterns was prepared at high OHÀ/SiO2ratio(more than2.0) and low temperature(50 C)for3days.It has been found that,without organic template,calcined EMC-2 (denoted as EMC-2-C)showed better directing effect than as-synthesized one for the synthesis of EMC-2-SOF.Besides,the variation of SiO2/Al2O3molar ratio in original gel for synthesizing EMC-2-SOF was affected by OHÀ/SiO2ratio.A bestfit between the ratio of SiO2/Al2O3and OHÀ/SiO2has been achieved.At OHÀ/SiO2¼2.0,the relative crystallinity of EMC-2-SOFfirst increased,then got to100%at SiO2/ Al2O3¼50,andfinally decreased with SiO2/Al2O3ratio increasing.Meanwhile,by changing H2O/SiO2 ratio from46.6to30,yield of EMC-2-SOF increased from15.8to33.4wt.%.A relationship of mutual compensation among three intensive parameters in preparing zeolites(alkaline,temperature and crystallization time)has been used to improve the crystallinity of EMC-2-SOF.When gels with SiO2/ Al2O3¼25,OHÀ/SiO2¼2.0,H2O/SiO2were crystallized at55 C for12e20h,all the samples had crystallinity above100%with the yield over25wt.%.©2015Elsevier Inc.All rights reserved.1.IntroductionAs a pure phase,zeolite EMC-2(EMT type)wasfirst synthesized by Delprato and coworkers in1990by employing18-crown-6ether as structure direction agent(SDA)[1].It is a hexagonal polymorph of faujasite with a stacking of faujasite sheets differing from cubic phase of zeolite Y[2].This stack makes zeolite EMC-2possessing two types of cages:hypocage with0.61nm3void volume and hypercage with1.24nm3,pared with zeolite Y, which comprises only one supercage(1.15nm3void volume)with four12-ring windows,the hypercage of zeolite EMC-2comprises five12-ring windows[3e6].Hence,its bigger cavities and more windows may deal with nerve-wracking problem faced by zeolite Y with the proportion of bulky saturated hydrocarbons and aromatics increasing in crude oil[7].Usually,zeolite EMC-2is synthesized using18-crown-6ether as SDA,which is poisonous.Many approaches have been used in the past decades to reduce its content in the reacting mixture,for instance,adding surfactant or auxiliary agent of Na3PO4$12H2O[8,9], adopting continuous tumbling method during the entire aging and crystallization period[10],using a steam-assisted crystallization (SAC)method[2],etc.Even though the molar ratio of18-crown-6 ether/Al2O3has been greatly decreased to0.14[10],it still exists.On the other hand,the intergrowth of FAU/EMT phase has attracted many attentions since some properties of the intergrowth phases are better than those of the pure end members[11e13].However, another poisonous organics,15-crown-5ether or di-(azacrown ether)should be used[14].Up to2012,a template-free method was reported to synthesize ultra-small EMT type zeolite at30 C for36h at high alkaline(called as UEOF-2)[15,16].X-ray diffraction(XRD) pattern of these samples showed partial diffraction peaks of EMT-type zeolite,such as the diffraction of plane(100)and(101)at 2q¼5.87 and6.65 ,respectively.However,it lacks the diffraction of (103)plane of EMC-2at2q¼11.05 ,which has been recognized as one of the typical diffraction of zeolite EMC-2[13,17e20].Using seed crystals in place of organic template have made progress on organic-free synthesis of many zeolites[21e30].Seed crystals in the original gel can be the substrate zeolite for the*Corresponding author.Tel.:þ862223509932.E-mail address:liniu@(N.Li).Contents lists available at ScienceDirectMicroporous and Mesoporous Materials journal h omepage:w /l ocate/micro meso/10.1016/j.micromeso.2015.03.0231387-1811/©2015Elsevier Inc.All rights reserved.Microporous and Mesoporous Materials212(2015)73e79growth of crystal with the same or related structure [31e 43].In the present paper,we reported an organic-template-free method to synthesize pure EMT-type zeolite (denoted as EMC-2-SOF)with EMC-2seed assisting.The resulted products possessed high crys-tallinity with the XRD pattern matching very well with what syn-thesized by using 18-crown-6ether as template.2.Experiment 2.1.MaterialsThe following materials were used as source materials:sodium aluminate (NaAlO 2,Tianjin Guangfu Fine Chemical Research Insti-tute,China,98%)as an aluminum source,silica sol (Qingdao Makall,China,SiO 2¼27wt.%,H 2O ¼73wt.%)as a silica source and NaOH (Tianjin Jiangtian Chemical Technology Co.,Ltd.,China,!96.0%)aqueous solution as an alkali source.The 18-crown-6(Alfa Aesar,China,99%)ether was used as an SDA for the synthesis of zeolite EMC-2seed crystals.2.2.Synthesis of EMC-2seed crystalsEMC-2were synthesized following the method in literature [1]with the molar composition being 10SiO 2:1Al 2O 3:2.4Na 2O:1(18-crown-6ether):140H 2O.Starting gel were prepared as follows:NaAlO 2was dissolved into NaOH aqueous solution.Then the silica sol and 18-crown-16ether were added into the mixture with agitation for 2h.The starting gel was aged for 24h at room tem-perature.After that,the aluminosilicate gel was transferred into 20mL steel-stainless autoclave with a polytetra fluoroethylene liner for crystallization at 110 C for 15days under static condition.The solid product was filtered,washed with deionized water until a near neutral pH was achieved,dried overnight in room temperature.In order to remove the SDA cations,the as-prepared EMC-2seed crystals would be calcined at 550 C for 5h in air to obtain EMC-2-C.2.3.Seed directed synthesis of EMT-type zeolite from an organic-free routeWithout organic template,high-crystallization zeolite EMC-2-SOF was synthesized from the gel with the composition:(25e 50)SiO 2:1Al 2O 3:(25e 50)Na 2O:(750e 2330)H 2O:seed.EMC-2-C was used as seed crystals with 20wt.%relative to silica source.The starting gel were prepared as follow:an Al source was dissolved into NaOH aqueous solution,then silica sol was dropped into the mixture and then agitated for 1h.The EMC-2-C crystals were added just before transferring the gel into steel stainless autoclave.The gel crystallized at 50 C for 16e 168h under static condition.The solid product was filtered,washed and dried in air.2.4.CharacterizationThe powder XRD patterns was recorded on Bruker-D8using CuK a radiation (tube current 40mA,voltage 40kV).The scanning electron microscopy (SEM)images were obtained with a JEOL JSM-7500F scanning electron microscopy.The chemical analysis was used to analyze the SiO 2/Al 2O 3ratios of products.RamanTable 1Conditions for forming EMC-2from an organic-template-free system with seed assistant (20wt.%).Sample OH À/SiO 2SiO 2/Al 2O 3H 2O/SiO 2T/ C Time/h Y-solid wt.%Crystal./%Y-SOF wt.%ES-1310046.6503Â2414.034 4.8ES-235046.6503Â2413.273.29.7ES-333546.6503Â2417.68515.8ES-432546.6503Â24þimpurity*ES-5210046.6503Â2413.48311.1ES-625046.6503Â2422.510022.5ES-725020503Â2416.595.115.7ES-823546.6503Â2422.273.216.2ES-922546.6503Â2426.06115.8ES-1022540503Â2436.48430.6ES-1121546.6503Â24þimpurity ES-12110046.6507Â2416.187.814.1ES-1315046.6503Â2425.465.916.7ES-1415046.6507Â2425.565.816.8ES-1513546.6507Â24e 58.5e ES-1611546.6507Â24e 36.6e ES-1711046.6507Â24e 29.8e ES-181 5.1546.6507Â24FAU ES-190.85046.6503Â2434.746.316.1ES-200.85046.6507Â2439.245.918.0ES-210.65046.6503Â245531.717.4ES-220.65046.6507Â2436.243.715.8*þimpurity:there is impurity in the product;Y-solid:yield of solid;Y-SOF:yield ofEMC-2-SOF.Fig.1.XRD patterns of synthesized samples (A)without seed,OH À/SiO 2¼2,SiO 2/Al 2O 3¼25,crystallization at 50 C for 3days;(B)EMC-2-SOF synthesized by using 20wt.%EMC-2-C seed crystals from the gel with OH À/SiO 2¼2,SiO 2/Al 2O 3¼25at 50 C for 3days;(C)EMC-2synthesized by using 18-crown-16ether as template.Q.Mou et al./Microporous and Mesoporous Materials 212(2015)73e 7974investigation was performed on a Renishaw inVia Microscope.The laser used was Argon ion laser with 514.5nm excitation source with power output of 25mW.3.Results and discussion3.1.Synthesis of zeolite EMC-2-SOF with seed crystals assistant Adding EMC-2as seed crystals lead to the formation of EMC-2-SOF in a wide range of gel composition with SiO 2/Al 2O 3ratio from 10to 100,OH À/SiO 2ratio from 0.6to 3.0,H 2O/SiO 2ratio from 20to 46.6,temperature from 50to 70 C,and the period for crystalliza-tion being 16e 168h (Table 1).XRD patterns shows the presence of (103)plane diffraction of EMC-2-SOF at 2q ¼11.05 ,which matches well with that of pure zeolite EMC-2(Fig.1B,C)[1]and cannot be found in sample without seed crystal assistant (Fig.1A).Seed directing method not only getrid of organic templates,but also lead to the formation of pure phase EMT-type zeolite.High alkalinity is a typical condition in the seed-directing route to prepare zeolites.For example,OH À/SiO 2gets to 0.5in the seed-directing route to prepare zeolite Beta [22],while in the routine way using TEAOH as template,OH À/SiO 2is only about 0.2.This distinction also exists in the formation of EMC-2-SOF.An 18-crown-6ether directed EMC-2is usually obtained at low alkalinity (OH À/SiO 2<0.48)[48],whereas for EMC-2-SOF,the suitable ratio of OH À/SiO 2gets to 1.0e 3.0.With OH À/SiO 2¼3in the original gel,variation of SiO 2/Al 2O 3ratio from 15to 100leads to signi ficant changes in the products.SiO 2/Al 2O 3ratio changes from 15to 25,some impurities coexist with EMC-2-SOF in the product (Fig.2A,2B).Increasing SiO 2/Al 2O 3ratio to 35,impurities disappeared.The relative crystallinity of this sample gets to 85%relative to organic directed EMC-2(Fig.1A,ES-3).When SiO 2/Al 2O 3ratio is higher than 35(at 50or 100),the relative crystallinity of EMC-2-SOF turns to decrease rapidly (Table 1ES-1and ES-2).At OH À/SiO 2¼2,the relative crystallinity show similar trend to that of OH À/SiO 2¼3with SiO 2/Al 2O 3ratio varying from 25to 100.The difference is that the relative crystal-linity of sample ES-6getting to 100%at SiO 2/Al 2O 3¼50(Fig.3a).Decreasing OH À/SiO 2to 1,obtained samples always have a lower crystallinity in all the range of SiO 2/Al 2O 3ratio (from 25to 100),indicating the insuf ficient alkalinity (Fig.3a).A best fit of SiO 2/Al 2O 3and OH À/SiO 2ratio to give high crystallinity of EMC-2-SOF has been found:with SiO 2/Al 2O 3ratio below 35and OH À/SiO 2at about 2(Fig.3b,Table 1).However,if we focus on the yield of EMC-2-SOF,it has been found embarrassedly that in most cases the yield of most products is lower than 20wt.%,which is just the addition of seed crystals (20wt.%).So it is much important to make clear the situation of seed crystals during the crystallization.3.2.Effect of seed crystals on the formation of ECM-2-SOFBy adding 20wt.%EMC-2-C as seed crystals,a gel with SiO 2/Al 2O 3¼25,OH À/SiO 2¼2,has been crystallized at 50 C for 0e 72h.The XRD patterns of products are showed in Fig.4a.The original gel displays some trace peaks of EMT structure coming from seed crystals (Fig.4a-0h).These peaks increase rapidly aftercrystallizedFig.2.XRD patterns of synthesized samples with OH À/SiO 2¼3at 50 C for 7days with 20wt.%seed crystals,(A)original gel SiO 2/Al 2O 3¼15;(B)original gel SiO 2/Al 2O 3¼25;(C)original gel SiO 2/Al 2O 3ratio ¼35;with OH À/SiO 2¼2at 50 C for 3days with 20wt.%seed crystals,(D)original gel SiO 2/Al 2O 3¼50.Fig.3.(a)The relationship between SiO 2/Al 2O 3ratio and relative crystallinity with OH À/SiO 2ratio ¼1,2and 3;(b)the relationship between OH À/SiO 2ratio and relative crystallinity with original gel SiO 2/Al 2O 3¼25,35and 50.Q.Mou et al./Microporous and Mesoporous Materials 212(2015)73e 797524h (Fig.4a-24h e 72h).Is it the formation of EMC-2-SOF,or the residual seed crystals with all of others dissolved?In order to verify it,seed crystals have been treated solely under OH À/SiO 2¼2at 50 C.It has been found that only half of them remained after 72h (Fig.4b).It means that seed crystals can be partly dissolved under this condition.Meanwhile,a seed-free gel with SiO 2/Al 2O 3¼25has also been heated under OH À/SiO 2¼2at 50 C for 72h with a lot ofFAU-type crystals being obtained (Fig.1C).It means that the initial gel have not dissolved completely,and can crystallize under this condition.Thus,if the yield of EMC-2-SOF is lower than 10wt.%,it can be considered as coming from seed.When the yield gets over 10wt.%,the extra product should be attributed to seed crystals growing.Furthermore,as SiO 2/Al 2O 3ratio of EMC-2-SOF is only about 5.1(Table 2)and lower than that of seed crystals (SiO 2/Al 2O 3¼7e 10)[1e 6],higher yield means more crystal growth.All of these indicate that,similar to the work on seed directing synthesis of zeolite BEA [41e 45],the partial dissolving seed crystals become the substrate for the growth and reconstruction of EMC-2-SOF.Fig.5show the SEM images of seed crystals,seed treated under OH À/SiO 2¼2at 50 C for 72h and EMC-2-SOF.They display the partial dissolving of seed crystals and the morphology after growing.Raman investigation has also traced the time evolution of the gel during crystallization (Fig.6).In Raman spectra,bandatFig.4.XRD patterns of (a)original gel with SiO 2/Al 2O 3¼25for 0e 72h,respectively by adding 20wt.%seed crystals;(b)seed crystal of EMC-2-C (A),and treating under OH À/SiO 2¼2at 50 C for 72h (B).Table 2The relationship of OH À/SiO 2,SiO 2/Al 2O 3ratio and the SiO 2/Al 2O 3molar ratio of EMC-2-SOF.OH À/SiO 2ratio in original gelSiO 2/Al 2O 3ratio Original gelEMC-2-SOF 250 5.553355.16Fig.5.SEM images of (A e B):EMC-2synthesized by using organic template;(C e D):EMC-2treated in OH À/SiO 2¼2system at 50 C for 72h;(E e F):EMC-2-SOF obtained under OH À/SiO 2¼2with 20wt.%EMC-2as seed.Q.Mou et al./Microporous and Mesoporous Materials 212(2015)73e 7976498cm À1is correlated with the formation of even-numbered rings such as 4-rings,and the band around 1125cm À1corresponds to the stretching vibration of T-O.Formation of these two bands suggest the construction of the framework of EMC-2-SOF.It can be observed that,compared to seed crystal,these two bands are very weak in the Raman spectrum of the initial gel.With crystallization time over 24h,intensity of these two bands increase remarkably.This is in good agreement with XRD results.The directing effects of seed crystals have also been investigated using three forms of EMT type crystals.They are as-synthesized EMC-2,EMC-2-C (EMC-2calcined at 550 C for 5h)and H-EMC-2(EMC-2-C exchanged by NH 4þin 0.2M NH 4Cl solution,then calcinedat 550 C for 2h).Surely,the form of the seed crystals has shownsigni ficant difference for preparing EMC-2-SOF.EMC-2-C show thebest effect for preparing EMC-2-SOF with higher crystallinity compared to the other two seed crystals (Fig.7B,C).Furthermore,content of the seed crystals also in fluences the crystallinity of resulted products.In the case of SiO 2/Al 2O 3¼15,OH À/SiO 2¼3.0and H 2O/SiO 2¼46.6,the diffraction intensity of products first in-crease and then decrease with the seed/SiO 2ratio increasing from 5wt.%to 25wt.%(Fig.8).When 5wt.%seed has been used,XRD pattern of the resulted sample lacks the diffraction peak of (103)plane (Fig.8A).This peak appears when 15wt.%seed has been used (Fig.8B)and reaches the maximum value with the seed/SiO 2ratio being 20wt.%(Fig.8C).Further increasing seed content,impurity phase appears (Fig.8D).So directing effect of the seed crystals is determined by its amount.In order to obtain pure EMC-2-SOF,the seed/SiO 2ratio has been kept at 20wt.%in the research.3.3.Increasing the yield of EMC-2-SOF by optimizing crystallization conditionsIncreasing the yield is a dif ficult problem for seed-directing route of zeolite preparation.Many efforts have been made to get yield of zeolites exceeding 35wt.%[39,43e 47].Directing ef ficiency of seed crystals is usually determined by crystallization conditions,which depend on the structure type and composition of speci fied zeolite.For example,high silica zeolite Beta with 5-ring as the main second building unit cannot be formed from a system with OH À/SiO 2ratio over 0.7,even if seed-directing method has been used [39,44e 46].On contrast,zeolite structures containing 4-ring and 6-ring as the building unit (including EMC-2-SOF)usually form at low SiO 2/Al 2O 3ratio under high alkaline (OH À/SiO 2¼ 2.0e 3.3)[43,47e 49].Our investigations above have con firmed the crystal-lization conditions of OH À/SiO 2ratio (1e 3),SiO 2/Al 2O 3ratio (25e 50)in the gel and crystallization temperature (50e 70 C)for growing EMC-2-SOF,which is the base for optimization.It is well known that low SiO 2/Al 2O 3ratio,OH À/SiO 2ratio,and H 2O/SiO 2ratio favor the increasing of zeolites yield.At SiO 2/Al 2O 3¼25under OH À/SiO 2¼2,a little change of H 2O/SiO 2ratio ranging from 46.6to 40leads to not only the crystallinity of EMC-2-SOF increasing from 61%to 84%,but also its yield going up from 15.8wt.%to 30.6wt.%(Table 1,ES-9and ES-10).A series of changesFig.6.Raman spectra of seed crystal and the gels obtained at different crystallization time.Fig.7.XRD patterns of EMT-type zeolites (A)EMC-2synthesized by using 18-crown-16ether as template;(B,C,and D)EMC-2-SOF synthesized by using 20wt.%EMC-2,H-EMC-2and EMC-2-C seed crystals,respectively from the gel with OH À/SiO 2ratio ¼3,SiO 2/Al 2O 3¼15at 50 C for 7days;(E)EMC-2-SOF synthesized by using 20wt.%EMC-2-C seed crystals from the gel with OH À/SiO 2ratio ¼3,SiO 2/Al 2O 3¼35at 50 C for 7days.Fig.8.XRD patterns of synthesized samples,OH À/SiO 2ratio ¼3,SiO 2/Al 2O 3¼15at 50 C for 7days with different seed crystals content (A)5wt.%;(B)15wt.%;(C)20wt.%;(D)25wt.%.Q.Mou et al./Microporous and Mesoporous Materials 212(2015)73e 7977from 46.6to 20,all the yields of EMC-2-SOF samples increase to exceeding 20wt.%with the maximum of yield being 33.4at H 2O/SiO 2¼30(Table 3,ES-2-4to ES-2-8).However,their crystallinity are below 90.2%.Generally,increasing OH À/SiO 2ratio,solubility of silica increase accompanying with silica polymerization changing.The polymeri-zation degree of silicate decrease radically in a solution when alkalinity higher than OH À/SiO 2¼1[42,50].In the presence of 18-crown-6ether as template to synthesize EMC-2,faujasite layers can be formed at 110 C with OH À/SiO 2¼0.48and assembled by [Na e 18-crown-6]þto form EMT structure and inhibits impurities [6].High alkaline results in FAU or the intergrowth of FAU/EMT structure [51].EMC-2-SOF grows on the surfaces of seed crystals of EMC-2-C at low temperature.Surely,higher alkaline (OH À/SiO 2>3)not only leads to the corrosion of seed crystals and loss their directing role as substrate for the growth of crystals,but also de-creases zeolite yield.Alkaline,temperature and crystallization time,which called as ATT,are three intensive parameters in preparing zeolites with some interconnection among them.Under OH À/SiO 2¼2,with the temperature increasing from 50 C to 55 C,impurity appears.So the period of crystallization is decreased from 72h to 24,20and 16h.Results have shown that relative crystal-linity of all these samples (Table 3ES-2-9to ES-2-13)have increased to over 100%with their yields getting above 25wt.%.Especially,when seed crystals have been added after the gel had been treated at 50 C for 2h,the crystallinity of EMC-2-SOF has reached 112%(Table 3ES-2-13).It gives us some inspiration for the next work.4.ConclusionsSeed crystals have been used to synthesize zeolite EMC-2-SOF in the absence of 18-crown-6ether.EMT-type zeolite with XRD pat-terns matched very well with what obtained by using 18-crown-6ether as template has been prepared.The variation of SiO 2/Al 2O 3molar ratio in original gel for synthesizing EMC-2-SOF was affected by OH À/SiO 2ratio.A best fit between SiO 2/Al 2O 3and OH À/SiO 2ratio has been found.At OH À/SiO 2¼2.0,the relative crystallinity of EMC-2-SOF first increased and then decreased with SiO 2/Al 2O 3ratio increasing,and gots to 100%at SiO 2/Al 2O 3¼50.By changing H 2O/SiO 2ratio from 46.6to 30,yield of EMC-2-SOF increased from 15.8to 33.4wt.%.A relationship of mutual compensation among threeintensive parameters (alkaline,temperature and crystallization time)in preparing zeolites has been found and used to improve the crystallinity of EMC-2-SOF.AcknowledgmentsWe thank the Natural Science Foundation of Tianjin(12JCYBJC12700),MOE (IRT13R30)for financial support.References[1] F.Delprato,L.Delmotte,J.L.Guth,L.Huve,Zeolites 10(1990)546e 552.[2]M.Matsukata,K.Kizu,M.Ogura,E.Kikuchi,Cryst.Growth Des.1(2001)509e 516.[3]M.W.Anderson,K.S.Pachis, F.Pr ebin,S.W.Carr,O.Terasaki,T.Ohsuna,V.J.Alfredsson,mun.23(1991)1660e 1664.[4] C.Wu,K.Chao,J.Chem,Soc.Faraday Trans.91(1995)167e 173.[5]N.Hanif,M.W.Anderson,V.Alfredsson,O.Terasaki,Phys.Chem.Chem.Phys.2(2000)3349e 3357.[6] E.J.P.Feijen,K.D.Vadder,M.H.Bosschaerts,J.Am.Chem.Soc.116(1994)2950e 2957.[7]P.B.Venuto, E.T.Habib,Fluid Catalytic Cracking Zeolite Catalysis,MarcelDecker,Inc.,New York,1979.[8]J.Sun,M.Sun,C.Nie,Q.Z.Li,mun.24(1999)2459e 2460.[9]Y.Luo,J.Sun,W.Zhao,J.Yao,Q.Z.Li,Chem.Mater.14(2002)1906e 1908.[10]R.Wendelbo,M.St €ocker,H.Junggreen,H.B.Mostad,D.E.Akporiaye,Micro-porous Mesoporous Mater.28(1999)361e 375.[11]H.Li,J.N.Armor,Microporous Mater.9(1997)51e 57.[12]L.N.Belandría,C.S.Gonz alez,F.Aguirre,E.Sosa,A.Uzc a tegui,G.Gonz a lez,J.Brito,S.L.Gonz alez-Cort e s,F.E.Imbert,J.Mol.Catal.A Chem.281(2008)164e 172.[13] A.M.Goossens,B.H.Wouters,P.J.Grobet,V.Buschmann,Eur.J.Inorg.Chem.5(2001)1167e 1181.[14]J.Dhainaut,T.J.Daou, A.Chappaz,N.Bats, B.Harbuzaru,pisardi,H.Chaumeil,A.Defoin,L.Rouleau,J.Patarin,Microporous Mesoporous Mater.174(2013)117e 125.[15] E.P.Ng,D.Chateigner,T.Bein,V.Valtchev,S.Mintova,Science 335(2012)70e 73.[16] E.P.Ng,J.M.Goupil, A.Vicente, C.Fernandez,R.Retoux,V.Valtchev,S.Mintova,Chem.Mater.24(2012)4758e 4765.[17]J.P.Arhancet,M.E.Davis,Chem.Mater.3(1991)567e 569.[18] F.Chen,J.Ma,Z.Dong,R.Liu,J.Nanosci,Nanotechnology 14(2014)7293e 7299.[19]M.Khaleel,A.J.Wagner,K.Andre Mkhoyan,M.Tsapatsis,Angew.Chem.Int.Ed.53(2014)9456e 9461.[20]N.S.John,S.M.Stevens,O.Terasaki,M.W.Anderson,Chem.Eur.J.16(2010)2220e 2230.[21]G.Majano,A.Darwiche,S.Mintova,V.Valtchev,Ind.Eng.Chem.Res.48(2009)7084e 7091.[22] B.Xie,J.Song,L.Ren,Y.Ji,J.Li,F.S.Xiao,Chem.Mater.20(2008)4533e 4535.[23]G.Majano,L.Delmotte,V.Valtchev,S.Mintova,Chem.Mater.21(2009)4184e 4191.Table 3Optimizing crystallization conditions for forming EMC-2with seed assistant (20wt.%).Sample OH À/SiO 2SiO 2/Al 2O 3H 2O/SiO 2T/ C Time (h)Y-solid wt.%Crystal./%Y e SOF wt.%ES-2-123546.6503Â2422.27516.6ES-2-223540503Â24þimpurity*74ES-2-323535503Â24þimpurity 85ES-2-422546.6503Â2426.06115.8ES-2-522540503Â2436.48430.6ES-2-622530503Â243790.233.4ES-2-722530502Â2428.682.923.7ES-2-822520503Â2434.265.922.5ES-2-9225305524þimpurity 105ES-2-1022530552025.610225.6ES-2-1122530551625.010025.0ES-2-1222530552þ1627.410527.4ES-2-1322530582þ1230.911230.9ES-2-14225307020þimpurity 96ES-2-1522530701625.985.422.1ES-101 1.85046.6503Â2423.897.723.2ES-102 1.82530552Â2432.887.828.8ES-1031.65046.6503Â2427.748.813.5*þimpurity:there is impurity in the product;Y-solid:yield of solid;Y-SOF:yield of EMC-2-SOF;2þ12:before adding seed crystals,the gel is heated hydrothermally at 50 C for 2h,then add seed crystals and crystalized at some temperature for 12h.Q.Mou et al./Microporous and Mesoporous Materials 212(2015)73e 7978[24]Y.Kamimura,W.Chaikittisilp,K.Itabashi,A.Shimojima,T.Okubo,Chem.Asian J.5(2010)2182e2191.[25]K.Iyoki,Y.Kamimura,K.Itabashi,A.Shimojima,T.Okubo,Chem.Lett.39(2010)730e731.[26]Y.Kamimura,K.Itabashi,T.Okubo,Microporous Mesoporous Mater.147(2012)149e156.[27]Y.Kamimura,K.Iyoki,S.P.Elangovan,K.Itabashi,A.Shimojima,T.Okubo,Microporous Mesoporous Mater.163(2012)282e290.[28]Z.Wu,J.Song,Y.Ji,L.Ren,F.S.Xiao,Chem.Mater.20(2008)357e359.[29]T.Yokoi,M.Yoshioka,H.Imai,T.Tatsumi,Angew.Chem.Int.Ed.48(2009)9884e9887.[30]M.Yoshioka,T.Yokoi,M.Liu,H.Imai,S.Inagaki,T.Tatsumi,MicroporousMesoporous Mater.153(2012)70e78.[31]G.T.Kerr,J.Phys.Chem.70(1966)1047e1050.[32]G.T.Kerr,J.Phys.Chem.72(1968)1385e1386.[33] B.Lu,T.Tsuda,Y.Oumi,K.Itabashi,T.Sano,Microporous Mesoporous Mater.76(2004)1e7.[34]S.Kasahara,K.Itabashi,K.Igawa,Stud.Surf.Sci.Catal.28(1986)185e192.[35]R.D.Edelman,D.V.Kudalkar,T.Ong,J.Warzywoda,R.W.Thompson,Zeolites9(1989)496e502.[36]P.K.Dutta,J.Bronic,Zeolites14(1994)250e255.[37]L.Gora,K.Streletzky,R.W.Thompson,G.D.G.Phillies,Zeolites19(1997)98e106.[38]M.Itakura,I.Goto,A.Takahashi,T.Fujitani,Y.Ide,Microporous MesoporousMater.144(2011)91e96.[39]K.Honda,A.Yashiki,M.Itakura,Y.Ide,M.Sadakane,T.Sano,MicroporousMesoporous Mater.142(2011)161e167.[40]K.Nishi,R.W.Thompson,in:K.Schüth,S.W.Sing,J.Weitkamp(Eds.),Hand-book of Porous Solids,vol.2,WILEY-VCH,Germany,2002,p.736.[41]Q.Wu,X.Wang,X.Meng,C.Yang,Y.Liu,Y.Jin,Q.Yang,F.S.Xiao,MicroporousMesoporous Mater.186(2014)106e112.[42]T.Moteki,T.Okubo,Chem.Mater.25(2013)2603e2609.[43]Y.Kamimura,S.Tanahashi,K.Itabashi, A.Sugawara,T.Wakihara,A.Shimojima,T.Okubo,J.Phys.Chem.C115(2011)744e750.[44](a)A.Ogawa,K.Iyoki,Y.Kamimura,S.P.Elangovan,K.Itabashi,T.Okubo,Microporous Mesoporous Mater.186(2014)21e28;(b)C.W.Bunn,H.Emmett,Faraday Soc.Discuss.5(1949)119e132;(c)P.H.Egli,S.Zerfoss,Faraday Soc.Discuss.5(1949)61e66.[45] B.Xie,H.Zhang,C.Yang,S.Liu,L.Ren,L.Zhang,X.Meng,B.Yilmaz,U.Müller,F.S.Xiao,mun.47(2011)3945e3947.[46]K.Itabashi,Y.Kamimura,K.Iyoki,A.Shimojima,T.Okubo,J.Am.Chem.Soc.134(2012)11542e11549.[47]H.J.Lee,Y.M.Kim,O.S.Kweon,I.J.Kim,J.Eur.Ceram.Soc.27(2007)581e584.[48]Y.M.Liu,Z.Z.Yang,C.L.Yu,X.H.Gu,N.P.Xu,Microporous Mesoporous Mater.143(2011)348e356.[49] F.Dougnier,J.L.Guth,mun.9(1995)951e952.[50]R.R.Xu,W.Q.Pang,Chemistry of Zeolites and Porous Materials,Science Press,Beijing,2004.[51]O.Terasaki,T.Ohsuna,V.Alfredsson,J.O.Bovin, D.Watanabe,S.W.Carr,M.W.Anderson,Chem.Mater.5(1993)452e458.Q.Mou et al./Microporous and Mesoporous Materials212(2015)73e7979。