TS—1分子筛骨架钛原子引入过程的研究

采用廉价的四丙基溴化铵（ＴＰＡＢｒ）的模板剂合成了ＴＳ－１分子筛，在晶化过程中，运用ＸＲＤ，ＩＣＰ，ＩＲ，＾２９ＳｉＭＡＳＮＭＲ和ＵＶ－Ｖｉｓ光谱等表征手段，系统地研究了钛原子引入分子筛骨架的机制，观察到钛原子随分子筛的形成同步进入骨架的规律，另外，尽管在晶化初期固相中没有ＴｉＯ２结晶出现，但存在分散态的ＴｉＯｘ物种，随晶化时间的延长，液相中钛物种之间聚合的几率增加，使固相中ＴｉＯ２晶体不断形成。     

SAPO-34分子筛晶化机理的研究

采用ＸＲＤ，ＳＥＭ，ＩＲ和ＣＰ／ＭＡＳ及ＭＡＳＮＭＲ等手段，对快速水热合成ＳＡＰＯ３４分子筛的全过程进行了监测，研究了由原始凝胶到ＳＡＰＯ３４结晶体过程中固相物质的组成结构随晶化时间的变化规律．结果表明，ＳＡＰＯ３４晶核的形成过程既是一个硅氧、磷氧和铝氧四面体由无序排列的胶团到有序排列的晶格骨架的重排过程，同时又是羟基缔合脱水环化的过程．晶化分为晶化前期和晶化后期两个阶段．晶化前期，硅原子直接参与晶核的形成和晶粒的长大过程，生成Ｓｉ（４Ａｌ）结构；晶化后期，少量硅以同时取代一对磷铝原子的方式进入分子筛骨架形成Ｓｉ（３Ａｌ），Ｓｉ（２Ａｌ），Ｓｉ（１Ａｌ），Ｓｉ（０Ａｌ）等多种硅结构．但在整个晶化过程中Ｓｉ（４Ａｌ）结构的生成并不排除硅单独取代磷机理的共同作用．     

Ti-β分子筛的合成、表征与催化性能

采用水热晶化法成功地合成了Ｔｉβ分子筛．运用ＸＲＤ，ＩＲ，ＵＶＶｉｓ和ＳＥＭ等多种现代物理技术表征了合成的Ｔｉβ分子筛样品的物化特性，证明了它具有ＢＥＡ拓扑结构，结晶良好，且钛原子进入了分子筛的骨架，无非骨架钛存在，晶粒大小约为０３μｍ．考察了合成路线、晶化时间等因素对Ｔｉβ分子筛的影响，发现不同合成路线只对结晶度有影响，晶化时间在１０～１２ｄ较好．探针反应结果表明，Ｔｉβ分子筛对苯乙烯氧化具有较好的催化性能．     

SAPO-34分子筛晶化过程中硅进入骨架的方式和机理

采用 Ｘ Ｒ Ｄ, Ｓ Ｅ Ｍ, Ｉ Ｒ 和 Ｎ Ｍ Ｒ 等手段考察了 Ｓ Ａ Ｐ Ｏ３４ 分子 筛的晶化过 程,深入研 究了晶化过程中硅进入 Ｓ Ａ Ｐ Ｏ３４ 晶格 骨架的方式和机理． 结果表明 ,在 Ｓ Ａ Ｐ Ｏ３４ 分子筛的整个晶化过程中没有 Ａｌ Ｐ Ｏ３４ 分 子筛晶相生成． 在 初始 凝 胶的 制备 过 程中, 模板 剂 的添 加和 混 合凝 胶的 老 化处 理对 Ｓ Ａ Ｐ Ｏ３４ 晶化过程的进行起着关键性的作用． 晶化前 期（ ＜ ２５ ｈ） , 硅原子直接参与晶核的形成和晶粒的长大过程,形成 Ｓｉ（４ Ａｌ） 结构,此阶段基本上 可以排除硅取代磷机理的作用; 晶化后期（ ＞ ２５ ｈ） ,少量硅以取代方式进入分子 筛骨架形成 Ｓｉ（ ｎ Ａｌ）（ ｎ ＝ ０ ～４） 多种硅结构     

超大孔Fe和V－Ti分子筛的合成

水热法合成了具有超大孔ＭＣＭ－４１分子筛结构的含Ｐｅ和Ｖ－Ｔｉ分子筛，通过ＸＲＤ、骨架ＩＲ、ＥＳＲ、￣（２９）ＳｉＭＡＳＮＭＲ、紫外漫反射等测试表征证实，Ｆｅ原子在ＦｅＭＣＭ－４１分子筛骨架上，Ｖ和Ｔｉ同时进入Ｖ－ＴｉＭＣＭ－４１分子筛骨架。ＦｅＭＣＭ－４１的骨架红外谱除Ｆｅ分子筛的特征吸收峰６６０ｃｍ￣（－１）外，还显示９６０ｃｍ￣（－１）峰，ＥＳＲ谱出现高对称八面体环境Ｆｅ（Ⅲ）信号（ｇ＝２．０）和扭曲四面体环境Ｆｅ（Ⅲ）信号（ｇ＝４．２），而Ｖ－ＴｉＭＣＭ－４１的骨架红外９６０ｃｍ￣（－１）峰强度分别随分子筛中钛或钒的含量线性增强。约在ｇ＝１．９８处出现的超精细结构ＥＳＲ信号表明Ｖ以分散的不流动的Ｖ￣（４＋）形式存在，化学分析结果表明骨架上Ｔｉ和Ｖ原子相互间不排斥。     

Ti—β分子筛的合成,表征与催化性能

采用水热晶化法成功地合成了Ｔｉ－β分子筛。运用ＸＲＤ，ＩＲ，ＵＶ－Ｖｉｓ和ＳＥＭ等多种现代物理技术表征了合成的Ｔｉ－β分子筛样品的物化特性，证明了它具有ＢＥＡ拓扑结构，结晶良好，且钛原子进入了分子筛的骨架，无非骨架钛存在，晶粒大小约为０．３Ζμｍ。考察了合成路线、晶化时间等因素对Ｔｉ－β分子筛的影响，发现不同合成路线只对结晶度有影响，晶化时间在１０￣１２ｈ较好。探针反应结果表明，Ｔｉ－β分子筛对苯     

Ti－Al pentasil型分子筛的表征及其热稳定性能

用气固相同晶取代法合成了Ｔｉ－ＡｌＺＳＭ－５和Ｔｉ－ＡｌＺＳＭ－１１型分子筛，并测定了它们的ＩＲ光谱、ＵＶ－Ｖｉｓ光谱以及晶胞参数，证实Ｔｉ进入了分子筛的骨架．热稳定性能的研究表明，Ｔｉ进入骨架后，分子筛热稳定性基本不变．另外，当高温处理时，Ｎａ型含钛分子筛的结晶度下降，直至转化为方石英，９６０ｃｍ－１处钛的特征峰不会消失．     

TS-2钛硅分子筛合成原料和方法的改进

以硅溶胶为硅源,钛酸四丁酯为钛源,四丁基氢氧化铵（ＴＢＡＯＨ）为模板剂,采用改进的方法合成了高结晶度的ＴＳ２分子筛,并对所合成样品用ＦＴＩＲ,ＸＲＤ,ＳＥＭ,２９ＳｉＭＡＳＮＭＲ,ＩＣＰ和Ｎ２吸附等方法进行了结构表征．实验中发现原料内添加适量氨水可使产品晶粒减小,骨架钛含量增加,比表面积和孔容增大,有利于提高其催化活性．另外,将晶化后母液中的ＴＢＡＯＨ循环使用,也能得到结晶度高和催化性能良好的ＴＳ２．采用本文推荐的合成原料和方法可大幅度降低ＴＳ２的合成成本     

硅源及晶化时间对SAPO-5分子筛结构及性质的影响

分别以硅凝胶和正硅酸乙酯为硅源，通过改变晶化时间合成了系列ＳＡＰＯ５分子筛．用ＸＲＤ，ＭＡＳＮＭＲ和ＳＥＭ对分子筛的结构和形貌进行了表征．结果表明，以硅凝胶为硅源时，凝胶中的铝有３种面体配位状态．加热晶化很容易使凝胶转化为ＳＡＰＯ５分子筛，合成物的晶形更加规则．在４８ｈ内，延长晶化时间有助于硅进入分子筛骨架，使残余的Ａｌ２Ｏ３·Ｈ２Ｏ进一步反应，使骨架硅和铝的面体配位环境更加对称；超过４８ｈ后，硅开始游离出分子筛骨架，并使部分ＳＡＰＯ５转化为ＳＡＰＯ３４．以正硅酸乙酯为硅源时，硅和铝的反应活性均较低，凝胶中ＡｌＰＯ４及Ａｌ２Ｏ３·Ｈ２Ｏ的量均比四面体配位铝的量大．只有当晶化时间超过４８ｈ时，反应物中Ａｌ２Ｏ３·Ｈ２Ｏ才能完全转化．在此反应体系中，延长晶化时间有助于ＳＡＰＯ５的生成，使分子筛骨架硅的取代量更大，晶形更加规则，骨架铝的对称性更好．     

超大孔Fe和V—Ti分子筛的合成

水热法合成了具有超大孔ＭＣＭ－４１分子筛结构的含Ｆｅ和Ｖ－Ｔｉ分子筛，通过ＸＲＤ，骨架ＩＲ，ＥＳＲ，＾２９ＳｉＭＡＳ ＮＭＲ，紫外漫反射等测试表征证实，Ｆｅ原子在ＦｅＭＣＭ－４１分子筛骨架上，Ｖ和Ｔｉ同是进入Ｖ－ＴｉＭＣＭ－４１分子筛骨架。     

疏水硅沸石Silicalite-I)结构性质的表征

用粉末XRD, FT-IR, 29^Si MAS NMR, 对高硅HZSM-5沸石及疏水硅沸石Silicalite I进行结构性质表征。在室温下, 疏水硅沸石具有ZSM-5的单斜对称性。它的红外骨架振动谱及高分辨29^Si固体核磁共振谱均显示出高的分辨率。在红外光谱中, 3700和3500cm^-1左右的表面Si-OH基振动消失。表明疏水硅沸石晶格中的[SiO~4]四面体排列完美。由-Si-O-Si-构成的微也表面, 具有优良的疏水性。     

Characterisation of zeolitic materials with a HEU-type structure modified by transition metal elements: definition of acid sites in nickel-loaded crystals in the light of experimental and quantum-chemical results

Nickel-loaded HEU-type zeolite crystals have been obtained by well-known synthetic procedures and characterised by X-ray fluorescence (XRF), scanning-electron microscopy/ energy-dispersive spectroscopy (SEM-EDS), FT-IR, diffuse reflectance UV/ Vis spectroscopy (DR(UV/Vis)S) and X-ray photoelectron spectroscopy (XPS) measurements as non-homoionic and non-stoichiometric substances containing exchangeable hydrated Ni2+ ions in the micropores and nickel hydroxide phases supported on the surface. Thermogravimetric analysis/differential gravimetry (TGA/DTG) and differential thermal analysis (DTA) demonstrated that full dehydration below approximately 400 degrees C follows a clearly endothermic process, whereas at higher temperatures the zeolite is amorphised and finally partially recrystallised to Ni(Al,Si) oxides, detected by powder X-ray powder diffraction (XRD). The solid acidity of NiHEU, initially determined by temperature-programmed desorption (TPD) of ammonia to be 8.93 mgg(-1) NH3, is attributed to the weak acid sites (fundamentally Lewis sites) resolved at approximately 183 degrees C, and to the strong acid sites (essentially Br?nsted sites) resolved at approximately 461 degrees C in the TPD pattern. A more sophisticated study based on in situ/ex situ FT-IR with in situ/ex situ 27Al MAS NMR and pyridine (Py) as a probe molecule, revealed that the Lewis acid sites can be attributed primarily to Ni2+ ions, whereas the Br?nsted ones can probably be associated with the surface-supported nickel hydroxide phases. The spectroscopic measurements in conjunction with powder XRD and 29Si MAS NMR data strongly suggest that distorted Al tetrahedra are formed during the dehydration process and Py chemisorption/complexation (NiHEU-Py), whereas the crystal structure is remarkably well preserved in the rehydrated material (NiHEU-Py/R). The structural, electronic, energetic and spectroscopic properties of all possible nickel(II) aqua and dihydroxy complexes absorbed in the zeolite micropores or supported on the zeolite surface were studied theoretically by density functional theory (DFT). The computed proton affinity, found to be in the range 182.0-210.0 kcalmol(-1), increases with increasing coordination number of the aqua and dihydroxy nickel(II) complexes.     

Silicalite-1分子筛氢键诱导晶化机制的固体核磁共振研究

The flexible chemical composition of the frameworks with tunable pore size and geometry of molecular dimensions makes zeolites widely used in chemical and petrochemical industry fields. The understanding of crystallization mechanism is important for a rational design of new zeolite with target structure and property, which however is still a big challenge in the field of material science. In this work, the specific spatial correlations/interactions between the SiO^-···HO―Si hydrogen bonds within the charged framework of silicalite-1 (MFI topology) zeolite and the alkyl chains of tetrapropylammonium ion (TPA⁺) organic structure direction agents (OSDAs) were studied by one-dimensional (1D) and two-dimensional (2D) solid state-NMR spectroscopy in combination with other techniques, with the aim to shed light into the crystallization mechanism of silicalite-1. The "solvent-free" route was used to study the crystallization process. Silicalite-1 crystals were also prepared following the hydrothermal synthesis route. The structural properties of as-synthesized TPA-silicalite-1 samples during the crystallization were characterized by XRD and scanning electron microscopy (SEM) images, which showed the evolution of long-range periodic structure and cyrtal growth. The ¹H-²⁹Si CP/MAS NMR experiments showed that the reorganization of the silica or silicates occurred in the crystallization process. The ^lH-¹³C CP/MAS NMR experiments performed on the samples synthesized with different time indicated that the TPA⁺ ions in the amorphous samples experienced a constrained environment, forming the inorganic-organic composites. The splitting of the methyl carbon signal from TPA⁺ ions was observed in the ¹³C NMR spectra, which is the direct reflection of the interactions between the methyl groups and the silicate framework in the straight and zig-zag channels of silicalite-1. Two types of SiO^-···H―OSi hydrogen bonds (SiO^-···H―OSi hydrogen bond in-cage and SiO^-···H―OSi hydrogen bond between lamellae) have been identified by 2D ¹H double quantum (DQ)-single quantum (SQ) MAS NMR and ²H MAS NMR during the crystallization of silicalite-1. The SiO^-···H―OSi hydrogen bonds between lamellae are formed and gradually transformed into the in-cage ones during the crystallization process. Their functions have been revealed in the formation of silicalite-1: the SiO^-···H―OSi hydrogen bond in-cage provides the stereoscopic counterbalance for the positive charges from TPA⁺ ions and this stereoscopic electrostatic interaction is the key factor to transform inorganic-organic composites with the MFI structure property, even though the long-range periodic MFI structures have not been established yet; the SiO^-···H―OSi hydrogen bond between lamellae acts as a connector to assemble the silicate species together to generate the zeolite framework. ²H MAS NMR spectra show that the SiOH nests exist in the zeolite framework even though the long-range periodic structures have been fully established.     

Synthesis and Characterization of Ti-ZSM-5 in a Non-alkaline Medium in the Presence of Fluoride Ions

Ti-ZSM-5 was synthesized by hydro thermal crystallization in the presence of fluoride via using a non-alkaline medium. pH values were 5~7. SEM showed perfect Ti-ZSM-5 crystals and a large single crystal growing from the favourable medium. Substitution of titanium for silicon in the ZSM-5 framework led to a decrease of crystal size and of the length/width ratio. Electron microprobe analysis indicated a homogeneous distribution of titanium in the ZSM-5 framework. The unit cell parameters of the Ti-ZSM-5 determined by XRD increased with an increase in titanium content in the framework. TiO4tetrahedron vibrations were found in the IR spectrum. Si(1Ti) peakwas seen in the 29Si MAS NMR spectrum at -1O1ppm(from TMS) and 13CMAS NMR analysis verified the effect of (C3H7)4N F- occluded in thechannels. XPS study on the precursors, calcined and H2O2 adsorbed Ti-ZSM-5 was performed and some interesting results were observed.     

HCl处理后局部有序Y沸石的二次晶化

将商品 Y 型沸石用 HCl 处理后, 运用 X 射线粉末衍射, 透射电镜和扫描电镜、红外光谱及 27Al 和 29Si 魔角旋转核磁共振对其进行了表征. 结果表明, 酸处理后 Y 沸石接近无定形, 其长程有序性遭到破坏, 但还保留部分局部结构. 以不同浓度酸处理后的 Y 沸石为前驱体, 在 150 oC, 0.3 mol/L NaOH 条件下采用蒸汽辅助干胶转化法进行二次晶化, 可以获得丝光沸石, 其相纯度与前驱体的 Si/Al 密切相关. 随 Si/Al 比不同, 所得丝光沸石形貌由纳米针状堆积逐渐向微米单块状变化, 且其比表面积可达 400 m2/g 以上, 微孔孔容在 0.19 cm3/g.     

高硅FAU沸石与甲胺吸附物的相互作用

合成高硅沸石中所用的模板剂胺类分子与沸石骨架 Si—O基团间的相互作用机理尚不清楚 .迄今为止 ,沸石与吸附胺之间的相互作用的研究还只限于测定沸石酸性质 [1,2 ]、表面羟基活性位或了解模板分子在沸石骨架中的位置和状态 [3,4 ] .甲胺、乙胺在骨架完美的高硅 FAU(Y型 )沸石上的亲和性指数 AT 值 ,即被吸附有机物脱附峰温与该有机物的沸点之差分别高达 1 60与 1 5 0℃[5] .而在高硅 MFI(Silicalite-1 )沸石上为 1 60与 1 2 7℃ [6 ] .与大多数有机物不同 ,被吸附的胺类脱附时的吸热效应十分明显 .上述现象表明胺与高硅沸石骨架 O2 -…     

"Extracting" the Key Fragment in ETS-10 Crystallization and Its Application in AM-6 Assembly

The mechanism of crystallization of microporous titanosilicate ETS-10 was investigated by Raman spectroscopy combined with (29) Si magic-angle spinning (MAS) NMR spectroscopy, DFT calculations, and SEM imaging. The formation of three-membered ring species is shown to be the key step in the hydrothermal synthesis of ETS-10. They are formed by means of a complex process that involves the interaction of silicate species in the reaction mixture, which promotes the dissolution of TiO(2) particles. These insights into the mechanism of ETS-10 growth led to the successful development of a new synthesis route to the vanadosilicate AM-6 that involves the use of intermediates that contain three-membered ring species as an initiator.     

Methane dehydrogenation and aromatization in the absence of oxygen on Mo/HZSM-5: A study on the interaction between Mo species and HZSM-5 by using Al and Si MAS NMR

By using a high-resolution solid state nuclear magnetic resonance spectrometer with ²⁷Al and ²⁹Si probes, the interaction between Mo species and HZSM-5 of frsol|Mo/HZSM-5 catalysts has been studied. The results show that there is a strong interaction between Mo species and HZSM-5 zeolite. The framework aluminum in the zeolite can be easily extracted by the introduction of Mo species. The extractability of framework aluminum by Mo species increases with increasing Mo loading and the calcination temperature. The extraction process leads to the formation of non-framework Al at first and then a new crystalline phase of Al₂(MoO₄)₃. The dealumination of the catalyst having a Mo loading of 15% and had been calcined at 973 K is so severe that all the aluminum in the framework are extracted and no framework Al could be detected by ²⁷Al MAS NMR. The catalyst, therefore, lost its catalytic activity for methane dehydrogenation and aromatization in the absence of oxygen. The Si/Al ratio measured from ²⁹Si MAS NMR further confirms the dealumination process observed by ²⁷Al MAS NMR. The MAS NMR results give us an evidence that Al₂(MoO₄)₃ crystallites are much less active for the reaction.     

Effect of molecular oxygen on the variable-temperature 29Si MAS NMR spectra of zeolite-sorbate complexes

Structure determinations of siliceous zeolite-sorbate host-guest complexes by solid-state NMR require highly resolved 29Si MAS NMR spectra. As the temperature is lowered, the 29Si MAS NMR spectra of many zeolite-sorbate complexes become broadened such that the resolution of the individual 29Si peaks is lost, limiting the application of solid-state NMR for structure determination. It is shown that the 29Si peak widths are related to the 29Si T2 relaxation times and that the source of the 29Si relaxation and the line broadening is paramagnetic molecular oxygen in the channels of the zeolite. Removal of the oxygen by purging the sample with nitrogen gas leads to a dramatic increase in the resolution of the 29Si MAS NMR spectrum of the p-dibromobenzene/ZSM-5 complex. An analysis of the individual 29Si T1 relaxation times reveals that the oxygen molecules are localized mainly in the zigzag channels of ZSM-5, suggesting that the p-dibromobenzene molecules are located in the channel intersections.     

UV-Raman and NMR spectroscopic studies on the crystallization of zeolite A and a new synthetic route

UV-Raman and NMR spectroscopy, combined with other techniques, have been used to characterize crystallization of zeolite A. In situ UV-Raman spectroscopy shows that the starting gel for crystallization of zeolite A contains a lot of four-ring (4R) building units and the appearance of six-ring (6R) building blocks is the signal for crystal formation. (29)Si NMR spectroscopy results suggest that the starting gel is double four-ring (D4R) rich and during crystallization of zeolite A both α and β cages appear. (27)Al NMR spectroscopy results indicate the absence of Al (2Si) species in the starting gel, suggesting the absence of single 4R building units in the starting gel. Furthermore, composition analysis of both solid and liquid samples shows that the solid rather than liquid phase predominates for the crystallization of zeolite A. Therefore, it is proposed that the crystallization of zeolite A mainly occurs in the solid phase by self-assembly or rearrangement starting from the zeolite building units mainly consisting of D4R. The essential role of D4R is directly confirmed by successful conversion from a solution of D4R to zeolite A in the presence of NaCl, and the importance of solid phase is reasonably demonstrated by the successful synthesis of zeolite A from a dry aluminosilicate gel. By considering that the solid phase has a major contribution to crystallization, a novel route was designed to synthesizing zeolite A from the raw materials water glass (Na(2)SiO(3) in aqueous solution) and NaAlO(2), without additional water and NaOH; this route not only simplifies synthetic procedures, but reduces water consumption.