Synthesis of Aluminum‐Rich Analcime Using an Ethylene Diamine Derivative as Template

The hydrothermal synthesis of analcime (ANA) with N,N′‐dibenzyl‐N,N,N′,N′‐tetramethylethylenediamine (DBTMED) as template was systematically studied. The various parameters that affect the crystallization of analcime, such as temperature, time, Al source, and Si/Al ratio were investigated. Systematic variations of these parameters revealed that ANA was obtained from the reaction mixture with the optimized ratios of SiO₂/Al₂O₃ = 5–9.5 in presence of DBTMED, whereas template‐free clear solution methods require SiO₂/Al₂O₃ ratio of greater than 25. When experiments were conducted at 130 and 150 °C for 4 days, a mixture of analcime and zeolite P was present in the samples, and a pure analcime sample could be obtained with heating in the temperature range 160–180 °C. When microwave and conventional heating were used, analcime could be obtained after 2 days. The obtained products were characterized by XRD, SEM, and IR spectroscopy.     

Recrystallization of Zeolite Y to Analcime and Zeolite P with <SC>d</SC>‐Methionine as Structure‐Directing Agent (SDA)

In this study, the synthesis of template free zeolite Y and its recrystallization to two types of pure zeolite P and analcime in the presence of the amino acid d‐methionine as structure‐directing agent were investigated. The recrystallization occurred solely when specific heating cycles were applyed. A completely crystallized phase of zeolite Y for the mixture of zeolite P and analcime was observed in the presence of d‐methionine at a concentration of 0.015 <SC>m</SC>. The effect of different Si/Al ratios (2.3–9.3), crystallization temperatures (40–160 °C), and crystallization times (28–96 hours) on the achievement of two different zeolite types were studied as well. Pure zeolite P was obtained during conventional heating to 100 °C for 42 hours, whereas pure analcime zeolite was achieved by heating the mixture to 160 °C for 96 hours. The products were characterized by X‐ray diffraction, scanning electron microscopy, and IR spectroscopy.     

Ultrasonic‐Assistance and Aging Time Effects on the Zeolitation Process of BZSM‐5 Zeolite

The isomorphic substitution of boron into ZSM‐5 zeolite under static hydrothermal condition was investigated. Evaluation of hydrothermal synthesis of BZSM‐5 was performed by treating the synthesis mixture by different aging processes, namely, ultrasonic, static, stirring, and microwave‐assisted aging prior to the conventional hydrothermal treatment. The synthetic processes with different techniques of aging prior to the onset of conventional hydrothermal crystallization were compared with a process without any prior aging. The obtained results showed that the ultrasonic and microwave assisted aging shortened the crystallization time and altered the crystal size and the morphology of the obtained products. The characteristics of the synthesized products were obtained by FT‐IR spectroscopic, XRD and SEM techniques.     

铁掺杂方沸石的合成及其磁性化

采用水热合成法, 按摩尔比n(SiO2):n(Al2O3):n(Na2O):n(Fe3+):n(H2O)=2.3:1:3.9:(0.02, 0.04, 0.08):185配料, 三乙胺为模板剂, 草酸为铁离子的络合剂, 经过室温搅拌成胶, 170 ℃下于不锈钢反应釜晶化60 h, 合成了三种掺杂铁量不同的方沸石, 为了解决粉末沸石分子筛难以从使用料液中分离问题, 对合成铁掺杂方沸石700 ℃下进行氢气还原制得了磁性沸石. 利用X射线衍射(XRD)、傅立叶变换-红外(FT-IR)光谱和扫描电子显微镜(SEM)对制得的产品进行表征. 结果表明, 合成的铁掺杂方沸石与纯方沸石结构相同, 磁性化沸石结构发生了变化. 考察样品对水中氟离子和铅离子的吸附性能发现, 铁掺杂方沸石和磁性沸石对它们的吸附性能没有促进作用.     

Framework‐Substituted Bismuth Zeolite‐P: Synthesis and Characterization

Bismuth‐modified zeolite‐P (Bi‐ZP) was synthesized by hydrothermal methods during the phase transformation of analcime to zeolite‐P. The evolution of phase transformation of pure analcime to Bi‐ZP was investigated. The results showed that bismuth atoms were incorporated into the framework of the microporous zeolite‐P. The effect of various Bi/Al (0–3) and Si/Bi (1–5) mole ratios on the synthesis of bismuth modified zeolite were studied by X‐ray diffraction (XRD) technique and FT‐IR spectroscopy. Evolution of the growth process of Bi‐ZP spheres was carried out at different time intervals with XRD patterns and FE‐SEM images. The energy dispersive X‐ray (EDX) spectrum indicated the existence of bismuth atoms in the synthesized Bi‐ZP. Framework substitutions of bismuth were evidenced by a set of complementary characterizations such as diffusive reflectance UV/Vis (DRS) and Raman spectroscopy on the synthesized Bi‐ZP (Si/Bi = 1).     

Synthesis of Zeolite L. Tuning Size and Morphology

Summary. A convenient synthesis of zeolite L is presented. The size of the crystals can be tuned between 30 and 6000nm, spanning a volume range of seven orders of magnitude. The zeolite L crystals, which typically feature a cylindrical morphology, are synthesized with various aspect ratios ranging from elongated to disc-shaped. The importance of obtaining zeolite crystals with well-defined size and morphology is discussed in view of potential applications of zeolite L containing organic dye molecules as guests.This revised version was published online in February 2005. In the previous version the issue was not marked as a special issue, and the issue title and the editor was missing     

Isomorphous Substitution of Iron and Nickel into Analcime Zeolite

Studies on the effects of iron and nickel incorporation into the hydrothermal synthesis of ANA zeolite were carried out. The presented work reveals that pure Fe‐Al analcime is synthesized by using starting composition with a higher iron(III) content than reported in previous publications. Furthermore, the iron(III) and nickel(II) contents play important roles in the framework of the synthesized zeolite. XRD, FT‐IR spectroscopy, diffuse reflectance UV/Vis spectroscopy, nitrogen adsorption and SEM were used to characterize the synthesized zeolites. These investigations showed that loading of iron and nickel ions in ANA zeolite changes the pore size and morphology of analcime zeolite.     

Controlling of Solution Concentration on Nucleation During Hydrothermal Synthesis of Analcime

Hydrothermal experiments of analcime nucleation and glass dissolution were carried out in autoclaves under the conditions of autogeneous pressures, temperatures of 150 °C ～ 210 °C, and 0.25 M ～ 0.75 M NaOH solutions. The curves of the glass dissolution and analcime formation are S‐shaped. Yet, the two curves are essentially parallel to each other. The time required for a complete dissolution of glass or the commencement of analcime formation is shorter when the concentration of NaOH solution or the temperature is higher. The amount of the weight percent of analcime synthesized is obviously less than the glass dissolved at a given time of an experiment. The weight difference between glass dissolved and analcime (dehydrated) formed is calculated to be represented as the solution concentration. During an experiment, the solution concentration increases gradually to a maximum, then decreases slowly to a constant value with time. On the other hand, nucleation is also gradually increased to a maximum, then is decreased finally to zero with time in a bell‐shaped curve. It is clear that nucleation of analcime is mainly controlled by the solution concentration.     

The Effects of Various Sources and Templates on the Microwave‐assisted Synthesis of BZSM‐5 Zeolite

Isomorphic substitution of boron into ZSM‐5 zeolite under microwave‐assisted hydrothermal conditions was systematically studied. When microwave treatment and conventional heating were used, BZSM‐5 zeolite could be obtained within one day, whereas the synthesis of BZSM‐5 under conventional hydrothermal conditions took five days at 180 °C. Various parameters that affect the crystallization of BZSM‐5, such as templates, crystallization time, the silicon source and the Si/B ratio were investigated. Systematic variations of these parameters revealed that this zeolite can be obtained from the reaction mixture with optimized ratios of Si/B > 0.6. Among various tested sources, tetraethylorthosilicate (TEOS) turned out to be the best source for synthesis of borosilicate zeolite and further investigations were done with TEOS as silicon source. The obtained products were characterized by XRD, SEM, and IR spectroscopic techniques.     

双杂原子Ti—Fe—ZSM—5分子筛的合成与表征

在无碱离子存在下，分别采用四丙基溴化铵（ＴＰＡＢｒ）和价格低廉的１，６－己二胺（１，６－ＨＤＡ）和正丁胺（Ｒ－ＮＨ２）模板剂合成了双活性中心的Ｔｉ－Ｆｅ－ＺＳＭ－５分子筛，对沸石产物的我一及结构进行了表征，并利用苯酚羟基化反应及气相色谱分析方法证明其有双活性中心离子存在及协同作用的催化氧化性能。     

真空原位水热合成法快速合成A型分子筛膜

采用真空原位水热法在管状αAl2O3基膜上快速合成了A型分子筛膜;采用XRD和SEM方法表征了膜的性质;研究了真空度对A型分子筛膜性能的影响。在外加真空作用下,分子筛晶粒可以均匀、快速地迁移到基膜表面形成分子筛膜,从而可以在较短时间里合成均匀、连续的分子筛膜。     

Combinatorial Approach to the Hydrothermal Synthesis of Zeolites

One hundred or more solid-state syntheses can be conducted in parallel and employed for the combinatorial hydrothermal syntheses of zeolites by using a novel multiautoclave design. The operation of the multiautoclave was ascertained by the reinvestigation of the complete Na₂O-Al₂O₃-SiO₂ ternary system in a single experiment. In the picture on the right, the shaded areas on the left show the crystallization fields of the different phases obtained.     

Synthesis and Characterization of Titanium Silicalite Modified by Noble Metal

With good potentials for ulterior savings in capital and production costs, onsite hydrogen peroxide production followed by its conversion to organic oxides without refining, is being regarded as an attractive route and promising technology to the production of organic oxides. The key point of the direct oxidation technology is the design and preparation of the bifunctional catalysts used therein. Herein, we present such bifunctional solid materials, which is one new modified titanium silicalite with incorporated noble metal (denoted as NMTS) with a hollow structure, which means for example that it hasintra‐particle voids. The samples were characterized by various instruments. Its catalytic properties in the direct epoxidation of propylene were also investigated, the results showed that NMTS is an excellent catalyst for the direct preparation of organic oxides from one‐pot process.     

超声老化对MCM-49分子筛合成的影响

 以六亚甲基亚胺为模板剂,在静态水热合成条件下,考察了超声老化对MCM-49分子筛合成的影响. 结果表明,凝胶经超声老化处理后,即使使用比表面积小的硅源(硅胶或白碳黑)也能合成出不含杂晶且结晶良好的MCM-49分子筛. 超声老化处理缩短了MCM-49分子筛的晶化时间,扩大了分子筛的晶化范围,同时降低了模板剂的用量. 合成的MCM-49分子筛结晶度高,颗粒度小.     

ZSM-35 分子筛的静态合成和晶化机理

 以环己胺为有机模板剂, 硅溶胶为硅源, 采用静态合成法在 220 ºC 的水热体系中制得了 ZSM-35 分子筛纯相. 当初始凝胶中含有一定量的 K+时, 在晶化过程中, K+与Na+的共同作用可以很好地抑制混晶丝光沸石的生成, 且当 n(K+)/n(K+ + Na+) = 0.3 时, 制得的 ZSM-35 分子筛晶化度最高. 利用 X 射线衍射和紫外拉曼光谱对分子筛形成的最佳条件以及晶化机理进行了研究. 发现合成初期前体中含有五元环和六元环的硅物种构筑单元. 通过水热晶化过程, 与硅酸盐的五元环或六元环有关的 450 cm–1 处紫外拉曼谱峰增强, 在晶化后期, 随着无定形凝胶逐渐被消耗, 在 421, 312 和 215 cm–1 处出现新的 ZSM-35 结构的特征拉曼谱峰, 说明这些环物种相互聚集最终形成了 ZSM-35 分子筛.     

羟基自由基在沸石分子筛合成中的作用

沸石分子筛由于具有独特的形选催化作用及可调的酸性, 已成为化学工业中最重要的固体催化材料. 沸石分子筛的合成主要基于碱性条件下的水热晶化, OH^?被认为起到催化硅铝物种的解聚及聚合作用. 近年来, 研究者发现了羟基自由基加速分子筛的水热晶化机制. 通过利用紫外光照射或芬顿反应等物理或化学方法向分子筛合成体系引入羟基自由基, 可以实现沸石分子筛的加速晶化及高硅沸石分子筛的合成. 理论计算结果表明, 羟基自由基可以促进Si—O—Si 键的断裂和重新生成, 从而显著加快分子筛成核并促进硅原子进入骨架. 本综述介绍了羟基自由基在沸石分子筛晶化方面的最新研究进展, 探讨了羟基自由基的主要作用和优势, 并对沸石分子筛合成的羟基自由基路线发展前景进行了展望.     

磷酸盐辅助一步合成介孔Beta分子筛

在合成纳米Beta分子筛的体系中添加磷酸二氢钠等无机盐,通过一步晶化制备介孔Beta分子筛.纳米分子筛组装形成的二次粒子克服了传统纳米粒子难以过滤分离的问题,同时所形成的粒间介孔改善了分子在催化剂内的扩散从而提高催化反应效率.采用X射线衍射、扫描电镜、氮吸附-脱附和氨程序升温脱附等表征方法对材料进行表征,结果表明磷酸二氢钠的用量对介孔体积有很大影响.当NaH2PO4/SiO2摩尔比为0.1时,合成的材料具有较好的孔结构和酸性,并在叔丁醇与苯酚的液相烷基化反应中表现出最好的催化活性.     

Hydrothermal Stability of the Novel Zeolite Type LSX in Comparison to the Traditional 13X Modification

Ion‐exchanged LSX (Si/Al = 1.02) and 13X (Si/Al = 1.18) zeolite series (Li, Na, K, Rb, Ca, Sr, Ba exchanged) were hydrothermally treated at temperatures between 423 K and 513 K in liquid water under autogeneous water vapour pressure. Beside X‐ray powder diffraction, the molybdate method and the water sorption uptake have been used to characterize the treated samples. The LSX and 13X zeolites show a similar hydrothermal behaviour in spite of their different framework Si/Al ratios depending only on the type of introduced cations. Significant destabilizing effects were observed especially in presence of K and Rb cations as well as the bivalent Sr and Ba cations. The LSX zeolites are hydrothermally more stable than LTA zeolites of same cations despite their same chemical framework composition.     

高性能Silicalite-1分子筛膜的合成

 本文首次利用自制的多孔二氧化硅载体, 通过二次原位水热合成出具有较高分离性能的Silicalite-1分子筛膜, 对其进行了SEM表征, 并利用渗透气化装置对乙醇-水的分离能力进行了评价, 同时还研究了乙醇-水原料液温度对Silicalite-1分子筛膜分离性能的影响.     

Ultrasonic‐assisted Synthesis of Fe Nanoparticles in the Presence of Poly(N‐vinyl‐2‐pyrrolidone)

Zero‐valent iron particles were prepared by wet reduction chemistry assisted with ultrasonic treatment. Such prepared particles have uniform size, exhibit crystalline structure and show strong paramagnetic property. Their surface modification by coating poly(N‐vinyl‐2‐pyrrolidone) (PVP) was investigated. The resulting Fe(0)‐PVP particles were monodispersed and possessed enhancing magnetization saturation. Those synthesis conditions to control the particle size and distribution were exploited.