使用四乙基氢氧化铵作为有机模板剂和常规硅铝源直接合成SSZ-13沸石分子筛

使用四乙基氢氧化铵作为有机模板剂,利用常规铝源和硅源而不需要高硅Y沸石作为起始原料,同时加入适量的沸石晶种直接合成了SSZ-13沸石分子筛.所合成的沸石产物结晶度好,具有良好的水热稳定性,并在氨选择性催化还原(NH₃-SCR)反应中显示出优异的催化性能,为其在工业上广泛应用提供了可能.     

由新型铜胺络合物模板剂设计合成活性优异的Cu-SSZ-13分子筛

以低廉的铜胺络合物为新型模板剂, 成功地合成了含铜的 SSZ-13 沸石分子筛 (Cu-ZJM-1). 在合成过程中, 铜胺络合物既是模板分子, 又是催化活性组分铜物种的直接来源. 理论计算表明, 该模板分子的构型与尺寸恰好与构成 SSZ-13 分子筛结构的 CHA 笼相匹配, 因而可以成功地导向该沸石分子筛结构. 采用 X 射线衍射、扫描电镜、氮气吸附、红外、紫外-可见吸收光谱、差热-热重分析、氨气程序升温脱附及氢气程序升温还原等手段对样品的性质及模板分子的状态进行了系统表征. 结果表明, 所制 Cu-ZJM-1 样品为结晶度很高的 SSZ-13 沸石结构, 硅铝比和铜负载量可调且铜处于高分散状态, 在 NH3 选择催化还原氮氧化物反应中表现出优异的催化性能.     

Polymethylated [4.1.1] Octanes Leading to Zeolite SSZ-50

In this communication, we report on the discovery of novel zeolite compositions, SSZ-50. The zeolite has the RTH topology but can be made over a large silica-to-alumina range including no aluminum at all. The surprising capability to produce a broad compositional range comes from the use of a single organo-cation guest molecule in the zeolite synthesis. The molecule is a specific derivative from within a family of 2-aza [4.1.1] bicyclo octanes that were prepared employing a sequence of organic synthesis steps from a starting ketone. Other cage-based zeolites like SSZ-35,-36,-39 and MTN arose from the use of the other derivatives in this series. We also comment on the tendency of a variety of polymethylated organo-cations to produce RTH, the closely related ITE, or the intergrowth structure, SSZ-36.     

Organocations in zeolite synthesis: fused bicyclo [l.m.0] cations and the discovery of zeolite SSZ-48

A set of zeolite synthesis experiments is described where lattice substitution is varied in the context of the structure of particular structure-directing organocations (at times referred to as templates). In this particular series, the organocations are constructed as members of a fused bicyclo organonitrogen class of compounds, described as having ring construction [l.m.n], where n = 0. We show that these compounds can best be achieved from starting cyclic ketones that are converted to imines via a Beckman rearrangement reaction. A particular approach to the Beckmann reaction works best in our hands. In some instances isomeric organocations are made and separated. Often their use in zeolite synthesis led to different products. There is a high correlation for the space-filling details of the guest organocations and the type of crystalline host lattice developed in the synthesis. In one instance involving isomers of a decahydroquinoline derivative, a new zeolite, SSZ-48, is discovered and contains only one of the isomers. Characterization of the isomers and their use in the zeolites is followed by (13)C MAS NMR analyses. Some details of the new zeolite are given and it is shown that a reasonable symmetry operation predicting a 14-ring zeolite could be generated under similar conditions to SSZ-48 (a 12-ring zeolite).     

The synthesis,characterization, and structure solution of SSZ-58: a novel two-dimensional 10-ring pore zeolite with previously unseen double 5-ring subunits

The synthesis, structure solution, and characterization of the novel zeolite SSZ-58 are described. SSZ-58 was synthesized under hydrothermal conditions using 1-butyl-1-cyclooctylpyrrolidinium cation as a structure-directing agent. The framework topology of SSZ-58 was determined with the FOCUS Fourier recycling method. SSZ-58 possesses 12 tetrahedral atoms in the asymmetric unit of its highest topological symmetry, and to date it is the most complex zeolite structure solved from powder data. Rietveld refinement of synchrotron powder X-ray diffraction data in space group Pmma confirmed the proposed model. SSZ-58 contains layers of atoms that are linked together by double five-membered rings (D5R), or 5(2)4(5) subunits, that have not been observed before in any zeolite or zeotype structures. SSZ-58 possesses a two-dimensional channel system consisting of 10-membered ring pores that intersect to form large cavities circumscribed by 12- and 16-membered ring pores.     

SSZ-39分子筛的合成及应用进展

近年来,小孔八元环SSZ-39分子筛因具有特殊的孔道结构和物理化学性质,在小分子择形催化反应中展现出相对优异的催化活性、抗积碳性和水热稳定性.本文概述了SSZ-39分子筛的合成历程,包括不同种类有机模板剂的使用、特定硅源铝源的选择以及凝胶组成的调控等;简要总结了SSZ-39分子筛在甲醇制低碳烯烃、氮氧化物的选择性催化还...     

利用适用于SAPO-34的有机结构导向剂合成SSZ-13分子筛

硅铝分子筛SSZ-13和硅磷铝分子筛SAPO-34已广泛应用于已商业化的催化应用中, 如甲醇制烯烃反应(MTO)和氨气选择性催化还原反应(NH₃-SCR). 目前, 已有多种商业化的有机结构导向剂(OSDA)可用于制备 SAPO-34, 而用于合成SSZ-13的OSDA仍主要依赖经典的N,N,N-三甲基-1-金刚烷基氢氧化铵(TMAdaOH). 因此, 寻找具有较高性价比且可导向合成高硅铝比(SAR)SSZ-13的OSDAs具有重要意义. 本文使用3种可制备SAPO-34的OSDAs[二异丙胺(DIPA)、 二丙胺(DPA)、 正丁胺(nBA)]替代部分TMAdaOH, 发现即使不加入晶种也可合成出SSZ-13. 采用粉末X射线衍射(PXRD)和固体核磁共振(ss-NMR)分析方法对制备的SSZ-13进行了系统研究. 结果显示, 所合成的具有可调变SARs的SSZ-13负载Cu之后, 在NH₃-SCR性能上与商业化催化剂相当. 此外, 通过研究DIPA和TMAdaOH合成SSZ-13的晶化机理发现, DIPA的加入可以加快结晶过程、 提高产率并防止非晶相的形成. 本文提出的观点可为寻找更高效和商业化的SSZ-13结构导向剂及合成具有特定性质的SSZ-13提供参考.     

A Cationic Oligomer as an Organic Template for Direct Synthesis of Aluminosilicate ITH Zeolite

There are a large number of zeolites, such as ITH, that cannot be prepared in the aluminosilicate form. Now, the successful synthesis of aluminosilicate ITH zeolite using a simple cationic oligomer as an organic template is presented. Key to the success is that the cationic oligomer has a strong complexation ability with aluminum species combined with a structural directing ability for the ITH structure similar to that of the conventional organic template. The aluminosilicate ITH zeolite has very high crystallinity, nanosheet‐like crystal morphology, large surface area, fully four‐coordinated Al species, and abundant acidic sites. Methanol‐to‐propylene (MTP) tests reveal that the Al‐ITH zeolite shows much higher selectivity for propylene and longer lifetime than commercial ZSM‐5. FCC tests show that Al‐ITH zeolite is a good candidate as a shape‐selective FCC additive for enhancing propylene and butylene selectivity.     

Mechanochemical Pretreatment for Efficient Solvent-Free Synthesis of SSZ-13 Zeolite

The economical and environmentally benign synthesis of SSZ-13 zeolite was possible due to the mechanochemical activation of dry reagents by planetary mill. Contrary to manual grinding in a mortar, the proposed automatized approach is scalable and reproducible. This solvent-free process provided a huge gain in product/gel ratios, significantly minimized reaction space and organic structure-directing agent use, and allowed for the elimination of agitation. Obtained materials were comparable to the product of “classical” syntheses. The use of different silica sources resulted in SSZ-13 zeolites with various characteristics: different Si/Al ratio and crystal size.     

高硅SSZ-13分子筛膜二次水热生长过程

采用稀释模板剂合成溶胶在管状莫来石支撑体上制备高硅SSZ-13分子筛膜以研究膜的二次水热生长过程。对433 K下二次生长2~72 h的膜和底料进行表征,XRD表明膜和底料中的SSZ-13特征峰均在6 h后出现。底料中的晶粒尺寸基本不随晶化时间的延长而变化。在298 K和0.4 MPa测试条件下,433 K晶化72 h的SSZ-13分子筛膜CO₂渗透通量为2.08×10^-7 mol·m^-2·s^-1·Pa^-1,CO₂/CH₄理想选择性为24。探讨了SSZ-13分子筛膜的生长过程：涂覆在支撑体上的晶种首先溶解并形成大量有序的结构单元,诱导溶胶中晶粒形成并快速生长,晶粒沉积在支撑体的表面共生形成无缺陷的膜层。     

Dual template synthesis of a highly mesoporous SSZ-13 zeolite with improved stability in the methanol-to-olefins reaction

The dual template synthesis of zeolite SSZ-13 by use of trimethyl-adamantanammonium hydroxide and a diquaternary-ammonium mesoporogen induces considerable mesoporosity without impeding zeolite microporosity. The strongly improved accessibility of Br?nsted sites in mesoporous SSZ-13 increases its stability during application as an acid catalyst in the methanol-to-olefins reaction.     

Structure and synthesis of SSZ-63: toward an ordered form of zeolite beta

The synthesis, characterization, and structure elucidation of the borosilicate zeolite SSZ-63 are described. SSZ-63 is synthesized using the 1-cyclodecyl-1-methylpyrrolidinium cation as a structure-directing agent. The structural model for SSZ-63 was determined by comparison of its powder X-ray diffraction pattern with those of zeolite beta and its polytype structures. Whereas conventional zeolite beta may be described as a random intergrowth of polytypes A and B, SSZ-63 is more accurately described as a random intergrowth of polytypes B and C(H) (the hypothetical polytype C proposed by Higgins). Polytype C(H) is essentially an ordered intergrowth (of polytypes A and B) in which one of the crystallographic projections is equivalent to those in polytype A and another projection is equivalent to those in polytype B. Unlike zeolite beta, which possesses significant disorder related to layer shifts along both the a- and b-crystallographic axes, the structure of SSZ-63 has little disorder associated with the translations of layers in the a-direction. DIFFaX simulations of the powder diffraction patterns, electron diffraction, and high-resolution transmission electron microsocopy data all support the proposed model.     

Controlling photochemical reactions via confinement: zeolites

Zeolites, aluminosilicates, with well-defined internal architecture containing cavities, channels or cages, can accommodate a large number of organic guest molecules. Internal structure of zeolites is studded with cations, the counter-ions of the anionic framework. The internal constrained structure and the cations serve as handles for chemists to control the behaviour of guest molecules included within zeolites. Photochemical reactions carried out in zeolite are highlighted in this review.     

Synthesis and Catalytic Properties of ZSM-5 Zeolite with Alkyl-polyamine Triethylene-tetramine as Directing Agent

With alkyl-polyamine triethylene-tetramine as the structure-directing agent,aluminosilicate zeolite ZSM-5(MFI) crystals were synthesized and characterized by XRD,SEM,FTIR,and TG-DTA. The results indicate that the organic amine has a certain influence on the crystal shape and size. The alkaline condition was in favor of the crystallization of ZSM-5 zeolite in the triethylene-tetramine system. The catalytic activity of as-synthesized crystals was examined for the aqueous hydroxylation of phenol with hydrogen ...     

DFT计算结合固体NMR研究富铝SSZ-13的铝分布和Br?nsted酸性

具有菱沸石(CHA)结构的SSZ-13分子筛在甲醇制烯烃(MTO)及柴油机车尾气氨选择性催化还原(NH_3-SCR)反应中具有重要的应用,采用富铝SSZ-13可以调节MTO反应的烯烃选择性和提升NH_3-SCR的低温脱硝活性,因此SSZ-13中的铝含量和分布与对应的酸性决定了其催化性能。本文采用密度泛函理论结合固体核磁共振实验研究了富铝和富硅HSSZ-13的Al位置与Br?nsted酸强度的内在关系。通过计算取代能发现,对于孤立Al位,质子位于Al周围4个不同O位时能量差异较小,最稳定的B酸位点是O(1)―H。对于富铝SSZ-13,两个Al原子位于同一六元环的对位是Al-Si-Si-Al (NNNN)序列中最稳定的结构,而Al-Si-Al (NNN)序列中能量最优的Al分布是两个铝原子排布于六棱柱上下不同的六元环上。通过计算最稳定构型下的质子亲和势、NH3脱附能和吸附氘代乙腈后的1H NMR化学位移,发现富铝SSZ-13中含有Si(2Al)分布的NNN序列导致了其Br?nsted酸强度弱于高硅的分子筛。分峰拟合29Si魔角旋转核磁共振(MASNMR)谱图表明富铝SSZ-13中Si(2Al)的含量在43%以上,而吸附氘代乙腈后的1H MAS NMR实验显示富铝SSZ-13的桥羟基化学位移向低场移动,进一步证明富铝SSZ-13具有较弱的Br?nsted酸强度。     

Structure-direction in zeolite synthesis

The concepts of structure-direction in the synthesis of clathrasils and high-silica molecular sieves are reviewed. The effects of size, geometry, and chemical nature of the organic structure-directing agent on the crystalline structures that are formed are discussed beginning with clathrasils (0-dimensional pore systems) and ending with 12-ring zeolites with 3-dimensional pore systems. Emphasis is focused on the energetic interactions between the organic guest and the inorganic framework. The energetic stability of porous frameworks is compared to the stability of dense pure-silica phases and the effects of trivalent (Al, B) and divalent (Zn) tetrahedral heteroatoms on the structure of zeolites formed is reviewed. The application of structure-directing concepts are described using the syntheses of ZSM-18 and SSZ-26 as examples, and the control over long-range order in zeolites by structure-directing effects is illustrated by the purposeful variation of the stacking probability of SSZ-33-CIT-1 and FAU-EMT intergrowths.     

碳化硅上生长Cu/SSZ-13分子筛及其NH3-SCR催化性能

汽车尾气和柴油不完全燃烧所释放的NOx严重污染了大气环境.为了降低对大气的污染,可将其催化还原成氮气.氨气选择性催化还原(NH3-SCR)是使用较广泛的机动车高效脱硝技术.用于催化脱硝反应的催化剂有多种类型,分子筛具有特殊的孔道结构和骨架结构及高比表面积,因而已广泛用作脱硝反应催化剂.与传统三效催化剂相比,分子筛催化剂总体表现出更好的脱硝催化活性,但在高温下不稳定,容易失活,不耐热冲击,水热稳定性差.SiC具有耐酸碱、耐腐蚀、抗氧化、耐磨及良好的热稳定性和导电性,因此作为催化剂载体近年来引起广泛关注.但是其本身也存在许多缺点,如比表面积低、表面性质不活泼、不利于金属物种分散等.因此,本文通过原位水热法将SSZ-13生长在SiC表面,制备出新型催化复合材料SSZ-13@SiC.采用X射线衍射(XRD)、扫描电子显微镜(SEM)和N2吸附-脱附等手段研究了不同碱量和晶化时间对SSZ-13在SiC表面生长的影响,负载Cu后获得Cu/SSZ-13@SiC作为催化剂,研究了SiC对Cu/SSZ-13中高温下脱硝活性的影响规律.结果表明,碱含量会影响SSZ-13在SiC表面的结晶程度.当SiO2/NaOH ≥ 0.1时,SSZ-13有杂相出现,并且结晶度都不高; 当SiO2/NaOH < 0.1时,SiC表面会生长成纯相的SSZ-13晶粒且具有较高的结晶度.晶化时间也会影响SSZ-13在SiC表面的覆盖程度: 反应1 d时,SiC表面会生长零星的SSZ-13晶粒; 2 d时,SSZ-13达到全面覆盖; 3 d后,SSZ-13在SiC上的生长达到饱和,其比表面积达到最大值,约为201.3 m2/g.通过离子交换将不同含量Cu离子交换到分子筛表面,其中Cu(1.71)/SSZ-13@SiC样品具有最佳的脱硝活性,接近200 °C时,NO转化率就达到90%以上,到高温500 °C时,NO转化率仍能保持在70%以上.相比于未负载的Cu/SSZ-13,Cu/SSZ-13@SiC催化剂在NH3-SCR测试中具有更高的高温催化活性,同时催化活性窗口明显拓宽.上述结果说明SiC对Cu/SSZ-13的高温催化活性具有一定的提高和稳定作用.     

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.     

以四乙基氢氧化铵为模板并通过转晶法合成高硅铝比的SSZ⁃13沸石分子筛

使用四乙基氢氧化铵为有机模板剂,以低硅铝比(nSiO2/nAl2O3)的Y分子筛为铝源,通过转晶法制备结晶度良好的SSZ?13沸石分子筛。从凝胶配比方面考察了不同原料组成对分子筛合成的影响,并通过X射线衍射(XRD)、扫描电子显微镜(SEM)及电感耦合等离子体(ICP)表征水热反应过程中的物相、形貌、硅铝比等变化,揭示分子筛合成过程。氨选择性催化还原(NH3?SCR)反应显示该分子筛具有优异的催化活性,为其工业上的广泛应用提供了可能性。     

Molecular recognition: minimizing the acid–base interaction of a tunable host–guest system changes the selectivity of binding

Two new receptors incorporating a 4-n-butyl aniline moiety has been designed, synthesized and evaluated for their binding properties towards a series of ureido-glycine derivatives. The host design is based on an urea adamantyl host motif known from large generations of poly(propylene imine) dendrimers functionalized with urea adamantyl moieties on the periphery. The design of the host molecules was directed towards a study of the effects of basicity of an amine function versus the effect of molecular recognition on the binding strength as seen from comparing the results obtained in the present work with previously guest–host studies. The guest–host interaction features an electrostatic interaction and multiple hydrogen binding interactions, where the main difference between the hosts described here and previously described is a substitution from an amine to aniline. Anilines are weaker bases than aliphatic amines and they generally give lower binding constants when treated with acidic guest molecules. The association constants have been measured using NMR titrations and the nature of the guest–host system is discussed based on these results. A general decrease in binding affinities is observed upon changing from the trialkyl amine hosts to the dialkyl aniline based hosts. One exception was observed where the weaker base host had stronger affinity to one of the guests. Thus, when the basicity of the host is decreased other factors influence the binding such as a better geometric fit. A crystal structure of one of the receptors has been solved and it shows no intramolecular hydrogen bonding.