Ti-ZSM-5和B-ZSM-5分子筛大单晶的合成

具有ZSM-5结构的含钛和含硼分子筛是催化性能良好的新型杂原子分子筛,可分别作为碳氢化合物的氧化反应^[1]和制备高纯异丁烯的催化剂^[2]。近年来,有关这2种分子筛的合成已见报道^[1~4]。但其合成均采用碱性介质,成核和晶化都比较快,因此未能得到生长完美的杂原子ZSM-5型分子筛大单晶。     

弱酸性介质中Fe-ZSM-5型分子筛的合成与鉴定

在弱酸性介质中,NH_4F存在下,以四丙基溴化铵(TPABr)为模板剂,采用水热合成法成功地合成了Fe-ZSM-5型分子筛。合成中pH值为5—7。该分子筛原料为铵型,经高温灼烧后可直接转化为氢型。X射线衍射、扫描电镜及电子探针、红外光谱、顺磁共振谱、Si高分辨固体核磁共振谱、差热分析等对Fe-ZSM-5型分子筛的的研究确证了Fe对Fe-ZSM-5型沸石骨架的同晶取代。X射线光电子能谱和穆斯堡尔谱对Fe-ZSM-5分子筛原粉的研究表明,Fe-ZSM-5分子筛中铁的价态是以三价和二价共存。     

弱酸性介质中Ga-ZSM-5型分子筛的合成与鉴定

本文报道在弱酸性介质中, NH4F存在下, Ga-ZSM-5型分子筛的合成, 这种新的合成途径, 克服了在碱性介质中合成的缺点, 用多种手段研究了Ga-ZSM-5型分子筛结构与性能的关系, 为Ga对ZSM-5沸石骨架的同晶取代提供了充分的证据.     

碱金属盐对ZSM-5分子筛晶化的影响

Effect of different alkali metal salts on the crystal size and the crystallization rate of ZSM-5 zeolite was de-tailedly investigated in this paper. The samples prepared by adding the different alkali metal salts were character-ized by using XRD， TEM， TG-DSC， BET and IR techniques. The XRD results showed that， for the nanosized ZSM-5 zeolite， the characteristic peaks broadened on the XRD patterns in comparison with the microsized ZSM-5 zeolite. The SEM results verified that the crystal size of zeolites prepared by adding different alkali metal salts had different results， and adding NaCl， NaC₂H₃O₂ and KCl showed the better effect of reducing crystal size， which are about of 40～60nm size. The crystallization curve of adding the different alkali metal salts suggested that the crystallization rate was significantly affected by the anions in the alkali metal salt besides the cations. Moreover， the crystal size likewise depended on the anion in the alkali metal salt. In addition， the BET results suggested that the nanosized ZSM-5 zeolite possessed a larger outer surface area in comparison with the microsized ZSM-5 zeolite. The thermostability of the samples was determined by TG-DSC technique， indicating that the nanosized ZSM-5 zeolite had a poor thermostability as compared with the microsized ZSM-5 zeolite. The possible difference of the samples with different crystal sizes on IR spectra was also given.     

高硅ZSM-5分子筛和二次合成Ti-ZSM-5分子筛的结构

运用度角旋转（MAS）和交叉极化（CP）等核磁共振波谱和红外光谱技术，分别对采用不同模板剂制备的高硅ZSM－5分子筛和以此为母体，经气固同晶取代法得到Ti－ZSM－5分子筛的结构特性进行了研究．结果表明：在水热法合成高硅ZSM-5分子筛过程中，模板剂明显制约着所制得的分子筛的结构特性．通过选用合适的模板剂，可直接获得具有正交晶系结构的高硅ZSM－5分子筛．在随后的气固相同晶取代过程中，钛原子通过占据分子筛骨架中的缺陷位进入骨架，形成具有一定Ti／Si比例的钛硅分子筛（Ti－ZSM－5）。骨架结构中缺陷位的含量直接影响分子筛的载钛量。     

低温晶化对B-ZSM-5和Ti-ZSM-5物化性能的影响

 以改进方法合成的B-ZSM-5分子筛为母体,采用气固相法合成了Ti-ZSM-5分子筛,并以XRD,FT-IR,UV-Vis,XRF,SEM,ICP-AES和MAS NMR等手段对B-ZSM-5和Ti-ZSM-5进行了表征,考察了Ti-ZSM-5对苯酚羟基化反应的催化性能. 结果表明,合成B-ZSM-5时的前期低温晶化有助于晶粒的减小; 以其为母体制备的Ti-ZSM-5对苯酚羟基化反应具有优异的催化性能. 在n(PhOH)/n(H2O2)=3,n(Me2CO)/n(PhOH)=2.7,m(cat)/m(PhOH)=5%,T=353 K和t=6 h的反应条件下,苯酚转化率可达20%以上.     

气相转移法合成ZSM-5/SAPO-5复合分子筛

以磷酸、拟薄水铝石和硅溶胶为原料, 三乙胺为模板剂, 采用气相转移法合成了一系列ZSM-5/SAPO-5复合分子筛. 产物经X射线衍射、扫描电镜、X射线能量散射谱、红外光谱及N2 静态吸附法等手段对其进行了表征, 证明合成材料是以ZSM-5为核、SAPO-5为壳的双结构分子筛. 实验结果表明, 干胶制备条件及液相组成都影响复合分子筛的结晶. 晶化温度的提高和晶化时间的延长有利于分子筛结晶度的提高. VPT法可以减小SAPO-5和复合分子筛颗粒的直径, 改善SAPO-5在ZSM-5分子筛表面的分布. 重油裂化结果表明, 核壳结构复合分子筛对生成低碳烯烃的性能优于机械混合的样品.     

以异丙胺为模板剂合成ZSM-23分子筛

系统考察了异丙胺-硅溶胶-偏铝酸钠-水体系中合成ZSM-23分子筛的影响因素.结果表明,当投料SiO2/Al2O3比为60～150时能够合成出晶相单一、结晶度良好的ZSM-23分子筛.SiO2/Al2O3比、模板剂用量、体系的碱度以及水量均能影响合成产物的晶型.同时模板剂用量和SiO2/Al2O3比对ZSM-23分子筛的形貌影响很大.在优化的条件下,稳定合成了不同形貌的ZSM-23分子筛.     

一种在堇青石蜂窝陶瓷上合成ZSM-5分子筛的新途径

Cordierite honeycombs are widely used as mono lith reactors in high gas flux circumstances due to their high thermal stability and low-pressure drop,such as catalytic converters in automotive emission control. In recent years, some attempts have been made to support zeolites onto cordierite honey combs[1-4]. In view of the relative complex config uration of the cordierite honeycombs, there have been some difficulties to obtain a zeolite layer with an even and enough thickness on every channel wall by the traditional hydrothermal technique. In the present paper, we for the first time apply vapor phase transport (VPT) technique to the synthesis of ZSM-5 onto cordierite honeycombs. And, to verify the feasibility of this technique, we prepared the Cu/ZSM-5 monolith catalyst by ion exchange, and tested its catalytic performance for NO reduction with C3H8.     

杂原子分子筛B－ZSM－5的合成与表征

在碱性介质（ｐＨ＝１０）中，用四丁基溴化铵、硅溶胶、硼酸在水溶液中合成了一种新型杂原子分子筛──Ｂ－ＺＳＭ－５型分子筛。用Ｘ射线衍射、扫描电镜、热重等方法进行了表征和研究。     

微酸性介质中V－ZSM－5的合成与结构表征

在含氟的弱酸性介质中,以四丙基溴化铵为模板剂,以NH₄VO₃和VO²⁺为钒源合成出V-ZSM-5分子筛,运用XRD、SEM、IR、XPS、ESR等手段对其结构进行了表征,结果表明,钒进入了分子筛骨架,并且主要以正四价态存在。     

非碱性介质中分子筛的合成

分子筛的合成通常是采用含碱金属离子的强碱性体系,通过水热晶化法实现~[1,2]的.得到的分子筛原粉不但必须通过铵离子交换和焙烧才能转变为氢型催化剂,而且在该体系中晶体的粒度也较小.Guth等人~[3]首次报道了在非碱性介质F-离子存在下直接合成铵型ZSM-5的工作.除用四丙基溴化铵合成ZSM-5及其杂原子分子筛外~[4],尚未见到在非碱性介质中合     

Alcohol-Assisted Synthesis of Sheet-Like ZSM-5 Zeolites with Controllable Aspect Ratios

Sheet-like ZSM-5 has been regarded as a promising material for catalytic applications due to its diffusion superiority. However, it still remains a challenge to obtain a desirable sheet-like morphology because of the complex synthesis process of zeolites. Here, a facile strategy for synthesizing sheet-like ZSM-5 is developed by only adding ethanol as zeolite growth modifier in the synthesis gel. It is thought that ethanol might be preferentially absorbed on the {010} surface of zeolite crystals, interact with the exposed silicon hydroxyl groups on the crystal {010} facet, and suppress the growth of b axis, resulting in the sheet-like shape. Through finely tunning synthesis parameters, sheet-like ZSM-5 crystals with thin b-axis thickness of 90 nm and different aspect ratios could be obtained. Owing to its shorter diffusion path and optimized acidity, sheet-like ZSM-5 exhibits better catalytic performance than conventional ZSM-5 in the alkylation of benzene with ethanol.     

合成乙苯ZSM—5催化剂的FT—IR研究

ZSM-5沸石由于具有独特结构,作为新型的择形催化剂广泛应用于石油化工催化反应中.人们普遍认为这些催化反应是由于沸石的酸中心引起的,尤其是B酸中心,因此对此做了较多的研究.我们选用不同反应时间,苯与乙烯气相烷基化合成乙苯ZSM-5催化剂,用吡啶吸附方法研究了ZSM-5催化剂的酸性,结合催化剂活性考察数据,得到了一些有意义的信息.     

FTIR Spectra of Hexene-1 Adsorbed on ZSM-5 Zeolites

HZSM-5, Pt-exchanged and impregnated PtHZSM-5 zeolites were prepared, which have different characteristics of OH group, and the IR spectra of hexene-1 adsorbed on these zeolites were investigated.     

在含乙醇的硅铝凝胶中合成ZSM-5沸石

用含乙醇的硅铝凝胶水热晶化合成ZSM-5沸石.实验表明,乙醇能够促进ZSM-5沸石晶体的成核和生长,具有明显的模板剂作用.向含乙醇的凝胶中加入晶种可以进一步缩短晶化诱导期和晶化时间,并减小分子筛的晶粒度.晶种的粒度与分子筛产物的晶粒度有一定对应关系.采用搅拌晶化也能明显地减小ZSM-5沸石的晶粒度,同时影响晶体形貌.通过优化晶化条件和凝胶组成,成功合成出硅铝比在30～240范围内、结晶度较高的ZSM-5沸石分子筛,所得沸石孔道畅通,热稳定性、水热稳定性高,且具有较强酸性,具有良好的应用前景.