Zur Hydrierung von Kohlenwasserstoffen an Katalysatoren des Systems poröses Glas-Metall

The Hydrogenation of Hydrocarbons on Catalysts of the System Porous Glass-Metal The hydrogenation of hydrocarbons such as cyclohexen, benzene and styrene on metal catalysts (Ni, Pd, Pt) supported by porous glasses and zeolites was investigated in the gasphase. In dependence on the pore structure catalysts of the type porous glass-metal are able to a shape selective catalysis like zeolite catalysts.     

ZSM‐5 Zeolite Nanosheets with Improved Catalytic Activity Synthesized Using a New Class of Structure‐Directing Agents

A new series of multiquaternary ammonium structure‐directing agents, based on 1,4‐diazabicyclo[2.2.2]octane, was prepared. ZSM‐5 zeolites with nanosheet morphology (10 nm crystal thickness) were synthesized under hydrothermal conditions using multiquaternary ammonium surfactants as the zeolite structure‐generating agents. Both wide‐angle and small‐angle diffraction patterns were obtained using only a suitable structure‐directing agent under a specific zeolite synthesis composition. A mechanism of zeolite formation is proposed based on the results obtained from various physicochemical characterizations. ZSM‐5 materials were investigated in catalytic reactions requiring medium to strong acidity, which are important for the synthesis of a wide range of industrially important fine and specialty chemicals. The catalytic activity of ZSM‐5 materials was compared with that of the conventional ZSM‐5 and amorphous mesoporous aluminosilicate Al‐MCM‐41. The synthesis strategy of the present investigation using the new series of structure‐directing agents could be extended for the synthesis of other related zeolites or other porous materials in the future. Zeolite with a structural feature as small as the size of a unit cell (5–10 nm) with hierarchically ordered porous structure would be very promising for catalysis.     

An Extra‐Large‐Pore Pure Silica Zeolite with 16×8×8‐Membered Ring Pore Channels Synthesized using an Aromatic Organic Directing Agent

Extra‐large‐pore zeolites for processing large molecules have long been sought after by both the academia and industry. However, the synthesis of these materials, particularly extra‐large‐pore pure silica zeolites, remains a big challenge. Herein we report the synthesis of a new extra‐large‐pore silica zeolite, designated NUD‐6, by using an easily synthesized aromatic organic cation as structure‐directing agent. NUD‐6 possesses an intersecting 16×8×8‐membered ring pore channel system constructed by four‐connected (Q⁴) and unusual three‐connected (Q³) silicon species. The organic cations in NUD‐6 can be removed in nitric acid to yield a porous material with high surface area and pore volume. The synthesis of NUD‐6 presents a feasible means to prepare extra‐large pore silica zeolites by using assembled aromatic organic cations as structure‐directing agents.     

Phase Transformation Behavior of a Two‐Dimensional Zeolite

Understanding the molecular‐level mechanisms of phase transformation in solids is of fundamental interest for functional materials such as zeolites. Two‐dimensional (2D) zeolites, when used as shape‐selective catalysts, can offer improved access to the catalytically active sites and a shortened diffusion length in comparison with their 3D analogues. However, few materials are known to maintain both their intralayer microporosity and structure during calcination for organic structure‐directing agent (SDA) removal. Herein we report that PST‐9, a new 2D zeolite which has been synthesized via the multiple inorganic cation approach and fulfills the requirements for true layered zeolites, can be transformed into the small‐pore zeolite EU‐12 under its crystallization conditions through the single‐layer folding process, but not through the traditional dissolution/recrystallization route. We also show that zeolite crystal growth pathway can differ according to the type of organic SDAs employed.     

不同方法制备的脱铝Y沸石的孔结构

Y沸石脱铝有多种方法。由于在脱铝过程中发生水解、聚合、重排等反应,分子筛的孔结构将发生很大的变化,如形成空穴,甚至可导致骨架结构单元的崩塌,形成二次孔。由于不同的脱铝方法的脱铝机理不同,即使它们的脱铝程度一致,产生的孔结构也将不同,这必将导致它们的酸性质和催化性能的差异。目前关于Y沸石孔结构的研究报导还很少,尤其对SSY,US-SSY沸石孔结构的报导更为鲜见。本文用低温N_2吸附-脱附等温线和层厚t等方法,对四种不同方法制备的脱铝Y沸石(USY,DAY,SSY和US-SSY)的微孔、二次孔及其孔径分布(2.0～60.0nm)进行了初步研究,得到了一些有用的信息,为进一步研究其酸性质和催化性能打下了基础。     

Sustainable Synthesis of Pure Silica Zeolites from a Combined Strategy of Zeolite Seeding and Alcohol Filling

Currently, the synthesis of pure silica zeolites always requires the presence of organic structure‐directing agents (OSDAs), which direct the assembly pathway and ultimately fill the pore space. A sustainable route is now reported for synthesizing pure silica zeolites in the absence of OSDAs from a combined strategy of zeolite seeding and alcohol filling, where the zeolite seeds direct crystallization of zeolite crystals from amorphous silica, while the alcohol is served as pore filling in the zeolites. Very importantly, the alcohol could be fully washed out from zeolite pores by water at room temperature, which completely avoids calcination at high temperature for removal of OSDAs in the synthesis of pure silica zeolites.     

The influence of mechanical activation and the nature of a carrier on the structural and diffusion properties of zeolite-containing catalysts

The influence of mechanical activation and the nature of a carrier on the structural and diffusion properties of zeolite-containing catalysts, including the microporous and mesoporous structure of zeolites, was studied. Zeolite-matrix contacts were found to provide the accessibility of the inside volume of zeolite pores. In addition, new pores of a larger size appeared. The IR spectra of adsorbed molecules were used to determine the effective diffusion coefficients of methanol in the porous system of zeolites. It was shown that there was some optimum zeolite pore radius at which the largest diffusion coefficient was attained.     

N'-亚硝基去甲烟碱在沸石分子筛上的程序升温表面反应

使用程序升温表面反应技术，首次研究了沸石对于分子直径远大于其孔径的烟 草特有亚硝胺代表物N'-亚甲烟碱的（NNN）催化裂解作用．NNN依然能被沸石吸附 和催化裂解；沸石孔径和表面酸位都是影响催化分解N因素．计算表明：NNN很可能 以N-N-O官能团嵌人沸石孔道的形式进行吸附．介孔分子筛被首次用于催化裂催化 活性远远高于微孔沸石．     

An Extra-Large-Pore Pure Silica Zeolite with 16×8×8-Membered Ring Pore Channels Synthesized using an Aromatic Organic Directing Agent

Extra-large-pore zeolites for processing large molecules have long been sought after by both the academia and industry. However, the synthesis of these materials, particularly extra-large-pore pure silica zeolites, remains a big challenge. Herein we report the synthesis of a new extra-large-pore silica zeolite, designated NUD-6, by using an easily synthesized aromatic organic cation as structure-directing agent. NUD-6 possesses an intersecting 16×8×8-membered ring pore channel system constructed by four-connected (Q⁴) and unusual three-connected (Q³) silicon species. The organic cations in NUD-6 can be removed in nitric acid to yield a porous material with high surface area and pore volume. The synthesis of NUD-6 presents a feasible means to prepare extra-large pore silica zeolites by using assembled aromatic organic cations as structure-directing agents.     

Direct Synthesis of An Aluminosilicate POS Zeolite with Intersecting 12×11×11-Member-Ring Pore Channels by Using a Designed Organic Structure-Directing Agent

Large and extra-large pore zeolites have been widely applied in industrial areas as catalysts, adsorbents, etc. Among them, silica and/or aluminosilicate zeolites have been attracted great attention due to their excellent hydrothermal stability and strong acidity. However, a great deal of zeolite structures are still not available in the form of silica and/or aluminosilicate. Herein, we report the synthesis of pure silica and aluminosilicate large-pore zeolites, denoted as NUD-14 and Al-NUD-14, respectively, by using a designed cation 1-ethyl-4-phenylpyridinium as an organic structure-directing agent (OSDA). NUD-14 has an intersecting 12×11×11-member ring pore system, which is isostructural to the germanosilicate PUK-16 zeolite with a POS topology. The OSDAs can be completely removed from the framework by calcination. NUD-14 and Al-NUD-14 possess excellent acid and hydrothermal stabilities, superior to the germanosilicate POS zeolite. The incorporation of Al into the zeolite framework makes the Al-NUD-14 zeolite possess medium and strong acidities. The successful synthesis of NUD-14 consisting of a rare odd-member ring pore structure may provide a platform for interesting size- and shape-selective catalytic applications.     

The influence of pore structure on reaction mechanism of propylene dimerization in zeolite: A theoretical viewpoint

Molecular sieves have been widely used in the petrochemical industry as environment-friendly catalysts. The pore structure is an important factor influencing the catalytic performance of the zeolite. In this work, a combined Our own N-layered Integrated molecular Orbital and Molecular mechanics method was used to study the mechanism of propylene dimerization in four zeolites (ZSM-5, BEA, MCM-22, and MOR) with different pore structures. Comparing the stepwise mechanism and the concerted mechanism, it is found that the two mechanisms compete with each other in the macroporous BEA, MCM-22, and MOR zeolites, and both mechanisms are possible. However, in ZSM-5 zeolite with medium pore size, the propylene dimerization reaction tends to proceed according to the stepwise mechanism. Furthermore, no matter which mechanism is adopted, the activation energy of propylene dimerization reaction in MCM-22 is the smallest in the four zeolites, indicating that its MWW-type structure (A framework type defined by the International Zeolite Association) may be the most favorable pore structure for the reaction and possesses the highest catalytic activity.     

Fe-Zn-Zr/分子筛复合催化剂上CO2加氢合成异构烷烃Ⅰ.不同分子筛对催化剂性能的影响

 在Fe-Zn-Zr/分子筛复合催化剂上考察了不同类型的分子筛对CO2加氢反应性能的影响. 结果表明,不同分子筛对复合催化剂性能的影响不同,Fe-Zn-Zr/HY是合成异构烷烃有效的复合催化剂. 分子筛的酸性及酸强度对复合催化剂性能有较大的影响,中等强度和较高强度的酸性位有利于异构烃的生成.     

正电子湮没与沸石内静电场

本文测定了不同类型沸石的正电子寿命谱。发现o-Ps的湮没寿命, 与沸石静电场之间有良好的对应关系, 静电场愈强, 湮没寿命愈短。根据正电子寿命谱结果。含不同阳离子的Y沸石的静电场强弱次序为KY相似文献   

Structure of the first silicate molecular sieve with 18-ring pore openings, ECR-34

The three-dimensional microporosity of zeolite frameworks have allowed their widespread use in industry as heterogeneous catalysts, absorbents, and ion-exchangers. While the phosphate analogues of zeolites having up to 24 tetrahedral atoms in the pore openings are known, silicate-based zeolites have, until now, been limited to 14-membered ring pore openings. We now disclose the structure and characterization of the synthetic zeolite ECR-34, which can be prepared from a mixed alkali metal reaction gel containing tetraethylammonium (TEA) cations. Its structure has been determined from powder diffraction data and shows ECR-34 to be hexagonal with the dimensions a, b = 21.030(1) A, c = 8.530(1) A, containing one-dimensional, 18-ring pores with 10 A diameter free openings. ECR-34 is stable to 800 degrees C and is able to absorb and ion-exchange large organic molecules. The existence of ECR-34 suggests the potential of preparing other thermally stable silicate molecular sieves with extra-large pores.     

Synthesis of adamantane on zeolite catalysts

The synthesis of adamantane from tetrahydrodicyclopentadiene on zeolites with different framework structures was studied. The adamantane yield on HY zeolites is higher than on HM and HZSM-5 zeolites. Among various types of dealuminated HY zeolites the HEY and HUSY zeolites give higher adamantane yields than conventional HY zeolite. The changes in activity and selectivity of the main and side reactions are correlated with the acidity and the pore structure of the zeolites. To ion-exchange the HY and HUSY zeolites with Ni2+ and La3+ cations may further improve the activity and selectivity of the zeolite catalysts.     

A Stable Extra‐Large‐Pore Zeolite with Intersecting 14‐ and 10‐Membered‐Ring Channels

The development of inorganic frameworks with extra‐large pores (larger than 12‐membered rings) has attracted considerable attention because of their potential applications in catalysis, the separation of large molecules, and so forth. We herein report the synthesis of the new extra‐large‐pore zeolite NUD‐2 by using the supramolecular self‐assembly of simple aromatic organic cations as structure‐directing agents (SDAs). NUD‐2 is a high‐silicon‐content germanosilicate with interconnecting 14×10‐membered‐ring channels. The SDAs in NUD‐2 can be removed by calcination in air at 550 °C to yield permanent pores with a BET surface area of 500 m²g^?1. Both germanium and organic cations in NUD‐2 can also be removed by treatment with acid at lower temperature, thus not only affording recycling of germanium and SDAs, but also providing a highly stable siliceous zeolite. In addition, aluminum ions can be incorporated into the framework of NUD‐2. The NUD‐2 structure is yet another extra‐large‐pore zeolite synthesized by using the supramolecular self‐assembling templating approach, thus demonstrating that this approach is a general and applicable strategy for synthesis of new large‐ and extra‐large‐pore zeolites.     

不同来源的钛硅沸石的孔结构,酸性和催化性能

用气固相类质同晶取代和水热方法合成了Ｔｉ－ＺＳＭ－５和ＴＳ－１沸石，对它们的组成、孔结构、酸性和催化活性进行了比较。以季铵盐为模板剂水热合成的无铝ＴＳ－１沸石骨架Ｔｉ含量高，表面无强酸位，且随骨架Ｔｉ含量增加，沸石晶内由缺陷造成的二次孔数量增多。类质同晶取代的Ｔｉ－ＺＳＭ－５沸石骨架Ｔｉ含量有限，样品内尚保留部分骨架Ａｌ，沸石表面强弱酸位同时存在。增加沸石骨架Ｔｉ含量和晶内二次孔对提高苯酚过氧化氢     

改性Y沸石的孔结构与催化性能

测定了不同方法改性的Y沸石样品的N_2吸附和脱附等温线, 并计算了样品的微孔、大孔和二次孔的孔容和表面积, 以及样品的二次孔分布, 证实改性方法对样品的孔结构有显著的影响。同时, 还考察了不同尺码探针分子在改性Y沸石样品上的酸催化反应活性, 将所得数据与样品的酸量、酸强度和二次孔容相关联, 取得了满意的结果。说明对大尺码反应分子, 改性过程中生成的大孔径二次孔, 对提高沸石催化剂的反应活性是有利的。