The Synthesis and Properties of Two Catalytically Important Zeolites

With his discovery of stilbite in 1756, Cronstedt [1] recognized the existence of a new group of minerals consisting of hydrated “aluminosilicates” of the alkali and alkaline earth cations. While several members of the group may have similar or nearly identical compositions, each possesses its own, unique crystal structure. At present there are 35 known naturally occurring zeolites. The crystal structures have been determined for 27 and all but about 10 have been prepared synthetically. This paper will present the definition of zeolites and focus on the synthesis and physicochemical properties of two catalytically and commercially important synthetic zeolites, zeolite Y and zeolite ZSM-5.     

TUN, IMF and -SVR Zeolites; Synthesis, Properties and Acidity

The effect of synthesis conditions on the preparation and properties of three novel zeolites TUN, IMF, and -SVR was investigated and compared with MFI. X-ray powder diffraction, infrared spectroscopy, chemical analysis, sorption measurements, and scanning electron microscopy were employed to characterize the textural and chemical properties of these zeolites. FTIR spectroscopy in combination with pyridine as probe molecule was used to describe the type, concentration and acid strength of these zeolites. Zeolite -SVR was synthesized with Si/Al ratios higher than 100 in contrast with TUN and IMF having Si/Al ratios about 20–30, respectively. TUN, MFI and IMF zeolites exhibit similar concentrations of Brønsted and Lewis acid sites and also similar acid strength of Brønsted sites. In contrast, the presence of one vacancy/unit cell in the case of -SVR zeolite substantially changes its acidic properties. Generally, zeolites TUN and IMF exhibit similar acidic properties in terms of acid strength and Brønsted to Lewis acid site ratio like MFI and due to their slightly larger pores higher activities in catalytic reactions are expected.     

纳米ZSM-5分子筛的合成研究

相比于微米ZSM-5分子筛,纳米ZSM-5分子筛具有孔道短,酸量多,外表面积大,抗积炭失活等优势。通过添加分散介质、分散剂、矿化剂及晶种导向剂等手段抑或通过不同的合成方法,可以得到纳米ZSM-5分子筛。文章综述了纳米ZSM-5分子筛的合成影响因素及合成方法。     

两种三苯胺衍生物的合成及其光谱性质研究

以三苯胺为起始原料,经过甲酰化反应、Claisen-Schmidt反应和Knoevenagel反应,较高产率地合成了两种具有D-A-D型结构的三苯胺衍生物。光谱分析发现,两种化合物的最大吸收波长分别位于450 nm和506 nm,对应的最大发射波长分别位于558 nm和633 nm,二者都具有较大的斯托克斯位移,从而有利于荧光材料的应用。     

多级孔沸石的合成进展

综述了多级孔沸石的合成策略,分别介绍了硬模板法、软模板法、后处理法,同时对各种合成手段的优缺点做了一定的比较。     

The State and Catalytic Properties of Platinum and Palladium in Faujasite-type Zeolites

The extensive body of literature published on the physicochemical and catalytic properties of metal zeolites has been reviewed in detail by Minachev and Isakov [1]. Industrial processes in petroleum chemistry involving metal zeolite systems have been examined by Bolton [2], Quite recently Rudham and Stockwell [3] presented a review covering many aspects of catalysis by faujasites. The scope of the present review is far more limited since only platinum and palladium faujasites will be considered and the subject will be further restricted by deliberately ignoring the important domain of bifunctional catalysis. So far little attention has been paid to the rapid progress made in the knowledge of very small particles supported on zeolites. During the past few years improved methods of particle size measurements, and new methods of evaluating the location, the structure, and the electronic properties of metal, and reliable measurements of intrinsic rates of reaction have provided much information on highly dispersed metal in zeolites which deserves to be known not only by people in the zeolite club but also by all those concerned with very small supported particles. Indeed, the choice of focusing our attention on palladium and platinum in faujasites was governed by the fact that these materials are the best known and the best suited to investigate the properties of highly divided metals. Thus, even with high loading, platinum in faujasites can be obtained in very homogeneous states of dispersion with particle sizes ranging down to nearly atomic scale. This is not true for most of the metal-zeolite systems where encaged species are always found together with unreduced cations and/or larger particles. This is not true either for platinum on other supports where wider size distribution and larger sizes are present and where minute loadings prevent detailed structural investigations.     

The Surface Properties of Zeolites as Studied by Infrared Spectroscopy

Although the remarkable structural and surface properties of those crystalline aluminosilicates classified as zeolites have been known for some considerable time, it is only quite recently that their catalytic properties have been recognized and utilized. The properties of zeolites as catalysts have been recently discussed in detail in this journal by Turkevich [1]. Many review articles give details of their structural [2–5] and surface [6–9] properties, as studied by classical methods. This review will be restricted to information on zeolites obtained by applying one of the newer methods of studying the solid-gas interface-infrared spectroscopy.     

The Surface Properties of Zeolites as Studied by Infrared Spectroscopy

Although the remarkable structural and surface properties of those crystalline aluminosilicates classified as zeolites have been known for some considerable time, it is only quite recently that their catalytic properties have been recognized and utilized. The properties of zeolites as catalysts have been recently discussed in detail in this journal by Turkevich [1]. Many review articles give details of their structural [2-5] and surface [6-9] properties, as studied by classical methods. This review will be restricted to information on zeolites obtained by applying one of the newer methods of studying the solid-gas interface-infrared spectroscopy.     

The Effect of Silanization on the Catalytic and Sorption Properties of Zeolites

Silanizing a zeolite can result in significant beneficial changes to their catalytic and sorptive properties. It has been shown, however, that it is necessary to carefully control the reaction conditions when silanizing a zeolite. Apart from considerations such as the different effects of using vapor or liquid deposition procedures and static or flow systems, deposition temperature and the number of silanization/calcination cycles are of great importance. By careful control of the number of cycles it is possible to systematically modify the diffusional properties of the zeolite while at the same time inertizing the external surface acidity. On the basis of the changes in adsorption properties of the silanized zeolite it is suggested that diffusional changes are more likely due to blockage of pore entrances,resulting in a greater diffusion pathway, than due to a controlled narrowing of the pore openings. By careful control of the number of cycles (i.e., silanization followed by calcination)it is possible to systematically change the diffusional properties to whatever extent is desired. It is shown that the amount of Si deposited/nm2 is a good indicator of the process of silanization. The conversion of TEOS and the products of the silanization reaction at different temperatures have been used to propose a reaction pathway. Results shown for a variety of reactions indicate that silanized zeolites are able to significantly increase the yield of particular isomers as a result of the diffusional constraints resulting from the silanization process.     

含噁二唑四枝分子的合成与非线性吸收

选择噁二唑基团作为多枝化合物的“枝”，以苯甲腈基和咔唑基团为分子的“核”，合成了两个四枝化合物（BO-G2和NO-G2），进行了核磁共振和质谱的表征．从结构上看，BO-G2和NO-G2分别具有“D-A-A’-A-D”和“D＇-A-D-A-D’”电荷转移特征，后者具有pn结．吸收光谱和荧光光谱证实，NO-G2具有较大的激发态和基态偶极矩差值，存在着明显的分子内电荷转移和非线性吸收．     

含聚氧化乙烯嵌段的二元多嵌段共聚物的合成和性能

用遥爪羟基聚苯乙烯与聚乙二醇和二氯甲烷在氢氧化钾存在下合成了氧亚甲基连接的聚氧乙烯 -聚苯乙烯多嵌段共聚物 ,采用FT -IR、1HNMR、分子量测定和凝胶渗透色谱分析表征共聚物的结构 ,研究了共聚物的乳化性能和相转移催化性能。结果表明 ,该类共聚物具有较好的乳化性能和相转移催化性能     

锂渣合成NaX分子筛结构表征和吸附特性研究

采用水洗分离和碱熔消化方法对硫酸法生产碳酸锂过程中排放的废弃锂矿渣(锂渣)进行预处理,然后用水热合成制备NaX分子筛(NaX-1、NaX-2)。分析了原料锂渣中石英含量以及预处理前后锂渣物相变化;用XRD、SEM和TG-DTA等手段对锂渣合成NaX-1、NaX-2分子筛的物相、晶体形貌和热稳定性进行了表征,用真空重量法测定其对水的吸附性能,并与NaX分子筛标样进行了对比。结果表明,原料锂渣中石英含量为14.1%(wt);采用水洗分离石英和碱熔消化后的锂渣均可作为合成NaX分子筛的原料,所合成的NaX-1、NaX-2分子筛均在6.1°、10.0°、15.4°、20.0°、23.3°、26.7°、30.9°等出现NaX分子筛特征衍射峰,其晶体规整,呈八面沸石型;用碱熔消化处理后的锂渣合成的NaX-2分子筛,晶体粒径为1~2μm,比用水洗分离石英后的锂渣合成的NaX-1分子筛晶粒(3~5μm)小;NaX-1、NaX-2分子筛具有良好的热稳定性,在800℃下未发生晶格结构破坏;NaX-1、NaX-2对水的平衡吸附量分别0.3234、0.3208 kg·kg-1,与NaX分子筛标样(0.3303 kg·kg-1)接近。     

二芳基乙烯类光致变色化合物的合成及其光电性质研究

在氮气及-78℃条件下,合成了两种二芳基乙烯类光致变色化合物1,2-双(2-甲基-5-(4-N,N-二甲氨基苯基)噻吩-3-基)全氟环戊烯(Ⅰa)和1,2-双(2-甲基-5-萘基噻吩-3-基)全氟环戊烯(Ⅱa),通过紫外-可见吸收光谱、荧光光谱、循环伏安法对其光谱特性和电化学性质进行了初步研究。在254nm紫外光照射下,Ⅰa和Ⅱa的氯仿溶液均由无色变为蓝色,最大吸收峰分别为620和570nm,在适当波长可见光照射下,均从有色态返回到无色态。通过UV-Vis光谱考察了这两种二芳基乙烯类化合物在溶液中的光致变色反应的动力学特征,实验结果表明,二芳基乙烯类光致变色化合物的闭环反应属于零级反应,开环反应为一级。电化学研究表明,在溶液中,Ⅰa和Ⅱa可发生不可逆的阳极氧化反应。     

两个新的苯并噻唑衍生物的合成与光物理性质

以苯并噻唑、苯乙酰基和吡啶阳离子为电子受体，二乙烯基苯为共轭桥，合成了两个新的A-π-A’型苯并噻唑衍生物：4-（2-苯并噻唑）-乙烯基查尔酮（1）和4-{4-[2-（苯并噻唑）乙烯基]苯乙烯基}-N-甲基吡啶碘盐（2）．研究了它们在溶液和固体基质中的光物理性质．研究发现：染料2由于具有较强的极性和较好的平面性，从而具有较长的吸收、发射峰和较强的荧光发射．有机染料在聚甲基丙烯酸甲酯／溶胶-凝胶复合玻璃中的发光行为与聚甲基丙烯酸甲酯和溶胶-凝胶玻璃二者的基质性质有关，同时由于固体基质中分子发生聚集的可能性降低，荧光强度相对于同浓度溶液增强，稳定性提高．     

Synthesis, Characterization, and Catalytic Properties of Nu-1, FU-1, and Related Zeolites

The discovery of the striking catalytic properties of the Mobil zeolite ZSM-5 has been followed by a large and intensive research effort both in catalysis promoted by ZSM-5 and in the synthesis and properties of other highly siliceous zeolites. While the distinctions between ZSM-5 and some of the claimed new zeolites are barely perceptible (it would perhaps be invidious to name these zeolites), other new. highly-siliceous zeolites differ markedly from ZSM-5/ZSM-11 in structure and consequently in other properties as well. Zeolites Nu-1 and FU-1 have now been fairly well characterized in both physical and catalytic properties. Although their crystal structures have not yet been determined, it is clear that they are different from ZSM-5 (and indeed, any other published zeolite structure).     

纳米级ZSM-12分子筛的合成及表征

采用双季铵盐模板剂溴代1,4-二氮甲基哌啶基-丁烷,通过动态水热晶化法成功制备了纳米级ZSM-12分子筛。采用X射线衍射、扫描电镜、透射电镜、红外光谱分析及N2吸附-脱附技术等测试方法对所得颗粒进行了研究。所合成的颗粒呈长条形状,长约150 nm,宽约30 nm。所得的ZSM-12沸石结晶体结构完整,无明显骨架缺陷,富含微孔和介孔孔隙。介孔孔隙来源于ZSM-12纳米晶粒之间的堆积孔隙。在酸分布上,所得的HZSM-12分子筛的中强酸及B酸比例较多,使得该沸石在催化反应中具备优良的反应活性。     

Catalytically Assisted Self-Propagating High-Temperature Synthesis of Tantalum Carbide Powders

The use of gas-phase iodine and carbon dioxide as transport agents in the tantalum/carbon/tantalum carbide combustion synthesis system has been examined to determine the effects of transport agents on product composition and microstructure. Two tantalum reactant particle sizes, a range of transport agent concentrations, and total pressures were studied. The effects of the combustion conditions on product morphology and composition were evaluated using scanning electron microscopy, nitrogen adsorption (specific surface area), and X-ray diffraction analyses. The results of the investigation indicate that the presence of the iodine vapor and carbon dioxide significantly enhances the combustion synthesis process, leading to higher conversion efficiencies and influencing product microstructure. The results are discussed in the context of gas-phase and solid-phase transport models.     

两类水处理剂的合成及其絮凝能力比较研究

文章以丙烯酰胺（AM）和二烯丙基二甲基氯化铵（DADMAC）为单体,过硫酸钾为引发剂,采用溶液聚合的方法制备聚丙烯酰胺（PAM）及其共聚物丙烯酰胺—二烯丙基二甲基氯化铵（P（AM–DADM AC））,其分子量通过凝胶渗透色谱（GPC）进行了表征。将两种聚合物配制成一定浓度的稀溶液,即非离子水处理剂（WTA）和阳离子水处...     

Synthesis of Dihydropyrimidinones Using Large Pore Zeolites

Abstract  

A series of dihydropyrimidin-2(1H)-one (DHPM) belongs to one of the important class of therapeutic and pharmacological active compound, were synthesized through the multicomponent reactions (MCRs) of aldehydes, ethyl acetoacetate and urea, followed by the heterogeneous catalyzed Biginelli reaction. In the present endeavour, medium (ZSM-5) and large pore zeolites (Y, BEA and MOR) as well as dealuminated zeolites BEA, were studied as catalysts. An excellent activity for DHPMs synthesis is achieved by optimizing accessibility of the reactants to the active sites and the surface polarity of zeolite catalysts. Moreover, the mechanism of Biginelli reaction was studied by means of GAUSSVIEW energy calculations of adsorbed acylimine intermediate on zeolite by using the density functional method (DFT).     

两个锌金属有机框架的制备及非线性光学性质研究

采用二茂铁单甲酸以及邻羧基苯甲酰二茂铁的钠盐与醋酸锌在甲醇中自组装,得到两个金属有机框架{[Zn(FcCOO)_2(bbbm)]·2H_2O}n(bbbm=1,4-双(1-苯并咪唑)丁烷(1)和{[Zn(o-OOCC_6H_4COFc)2(4,4'-bipy)(H_2O)2]·2Me OH·2H2O}n(4,4-bipy=4,4'-联吡啶)(2)。通过EA、IR以及X-ray等多种手段表征了其分子结构,主要对它们在DMF溶液中的三阶非线性光学性能进行了研究。