同步X射线衍射与分子模拟研究AlPO_4-18骨架中N,N-二异丙基乙胺模板分子的位置和取向（英文）

Phase pure AlP O4 with the AlP O4-18(AEI) structure was synthesised using N,N- diisopropylethylamine as a template. Using a combination of X-ray powder diffraction and computational methods, the location and orientation of the N,N-diisopropylethylamine molecules inside the cages of the AEI structure were determined. Thermogravimetric analysis confirmed that the number of template molecules per unit cell was consistent with the diffraction study. We unequivocally show that only one template molecule is present in each cage of the crystalline AEI material. Our work demonstrates that a combined approach enables accurate structure resolution of such complex materials.     

SAPO-31分子筛的微波加热合成、表征及催化性能

分别以异丙醇铝和磷酸为铝源和磷源,二正丁胺为模板剂,采用微波加热法成功制得AlPO4-31分子筛,并对其晶化条件进行了优化.在优化的条件下同时合成了不同含硅量的SAPO-31分子筛,采用X射线衍射、N2物理吸附、扫描电镜、固体29Si核磁共振、程序升温脱附以及吡啶吸附的红外光谱等手段对其结构和酸性进行了表征,并考察了P...     

ZSM－5（核）／AlPO4－5（壳）双结构分子筛的合成与催化裂化性能

 采用X射线衍射、扫描电镜、X射线能量散射谱、红外光谱和核磁共振等多种物化方法对合成的ZSM－5（核）／AlPO4－5（壳）双结构分子筛进行了表征，证明这种材料具有以ZSM－5为核层、以AlPO4－5为壳层的双结构特征．考察了合成条件对ZSM－5（核）／AlPO4－5（壳）分子筛形貌的影响，发现ZSM－5分子筛的加入方式对产物的形貌有较大影响．重油裂化反应结果表明，ZSM－5（核）／AlPO4－5（壳）双结构分子筛的催化性能比ZSM－5和ZSM－5／AlPO4－5机械混合分子筛样品好，表现为原油转化率和低碳烯烃、汽油及柴油收率提高．     

Tripling of the unit cell volume of the non-centrosymmetric AlPO4-SOD after dehydration: a structural study of a reversible process

The structure of AlPO4-SOD, a microporous aluminophosphate synthesized in a quasi-nonaqueous system using dimethylformamide as template and solvent, was previously reported. Then, various solid state nuclear magnetic resonance techniques applied on the dehydrated compound at 200 degrees C were performed and suggested a rearrangement of one-third of the template molecules inside the sodalite cages and a tripling of the unit cell parameter c. We present here the structure determined from molecular modeling and Rietveld analysis on synchrotron data of AlPO4-SOD dehydrated under vacuum at 100 degrees C together with some solid state NMR experiments of the rehydrated product.     

New all-atom force field for molecular dynamics simulation of an AlPO(4)-34 molecular sieve

A force field of the triclinic framework of AlPO(4)-34, important in methanol-hydrocarbon conversion reactions, was developed using an empirical potential function. Molecular dynamics simulation of an AlPO(4)-34 triclinic framework segment of 1216 atoms, containing the template molecules isopropylamine and water, was performed with explicit consideration of atomic charges. The average RMS difference between instantaneous positions of the framework atoms during 1 ns simulation and their positions in the structure determined from single crystal X-ray diffraction was calculated, and the average structure of the flexible framework was determined. The computed Debye-Waller factors and simulated FTIR spectra are in good agreement with the experimental data. The new force field permits detailed molecular dynamics simulations of flexible, charged aluminophosphate molecular sieves which should lead to a better understanding of the catalytic processes and the crucial role played by templating molecules.     

Synthesis and pore formation study of amorphous mesoporous aluminophosphates in the presence of citric acid

Amorphous mesoporous aluminophosphates (AlPO) with high thermal stability were synthesized from Al(NO3)3 and H3PO4 in the presence of citric acid (CA). The effects of different synthetic conditions, such as pH value, citric acid content, and calcined temperature, on the formation of the mesoporous structure of AlPO materials were investigated. The results of N2 adsorption/desorption and other characterization means demonstrate that the presence of a certain amount of citric acid in the synthetic mixture can result in the formation of uniform mesoporous AlPO materials in a wide pH range from 3.5 to 10. Thermal gravimetry and differential thermal analysis suggest that the existence of a moderate interaction between citric acid and the AlPO network might be a critical factor in obtaining uniform mesostructure. Therefore, as an organic additive, citric acid can be regarded as a template for the mesopore formation of AlPO materials.     

SHG Materials Based on the AlPO4-5 Single Crystals

Large AlPO4-5 molecular sieve single crystals with high optical quality were synthesized hydrothermally by using TPA as template. As-synthesized crystals were calcined under O2 atmosphere to remove the organic templates in the channels. Disperse-Red-1 (DR1) and p-nitroaniline (pNA) molecules have been successfully incorporated into the one-dimensional channels of AlPO4-5 single crystals respectively by means of vapor phase diffusion. XRD patterns reveal that the loading of organic molecules has not destroyed the structures of AlPO4-5 crystals. Polarizing microscope and SHG results indicate that the DR1 and pNA molecules are well aligned in a preferred direction along the crystal channels. The different polarization-dependence SH intensity shows that different SHG processes occur in the DR1- and pNA-loaded AlPO4-5 crystals.     

正交晶系下AlPO_4－5类似物的骨架拓扑结构设计

ＡｌＰＯ_４－５分子筛是一种典型的具有十二元环主孔道的磷铝分子筛。它的骨架拓扑结构属六方晶系，我们发现这一结构可以演变成很多正交构型的骨架结构，本文采用计算机技术，在正交晶系中设计了与六方ＡｌＰＯ_４－５结构相关的６４种分子筛骨架拓扑结构，并计算了它们的理论ＸＲＤ谱图，讨论了它们存在的可能性，一个具有正交ＡｌＰＯ_４－５合成样品的ＸＲＤ谱图与所设计的结构中一个ＸＲＤ理论谱图吻合，证实了正交构型ＡｌＰＯ_４－５的存在。     

Molecular conformations of protonated dipropylamine in AlPO4-11, AlPO4-31, SAPO-34, and AlPO4-41 molecular sieves

The host-guest interactions in AlPO4-11, AlPO4-31, SAPO-34, and AlPO4-41 molecular sieves prepared using the same organic structure-directing agent, i.e., dipropylamine, are investigated by a combination of Raman, 13C and 1H MAS NMR, and computer modeling studies. It was found that the organic molecules trapped within the pores of these four AlPO4-based materials exist as their protonated form and adopt distinct conformations in order to fit well with the pore structure of each host. In particular, the presence of two different types of conformations of protonated dipropylamine in the circular 12-ring channels of AlPO4-31 has been ascertained.     

Computational investigation into the phase transitions from AlPO<Subscript>4</Subscript>-H<Subscript>3</Subscript>

Open-framework aluminophosphates constitute an important family of materials due to their enormous potential applications in catalysis, exchange and gas separation, such as aluminosilicate zeolites. These compounds, whose formations are promoted by the presence of organic templates, are constructed from alternation of AlO4 and PO4 tetrahedral with an Al/P ratio of unity. However, there are quite a number of AlPOs that contain 5- or 6-coordinated Al atoms which are coordinated to extra-fram…     

高质量AlPO4 -5分子筛大单晶的合成与表征

The AlPO4-5 molecular sieve has been synthesized hydrothermally by using tripropylamine (TPA) as the template, and pseudoboehmite and orthophosphoric acid as aluminum and phosphorus sources, respectively. The single crystals of AlPO4-5 with different sizes have been obtained by varying the molar ratio of reactants and the crystallization conditions (such as the temperature and time). The typical molar ratio of the reactive mixture is Al2O3∶P2O5∶TPA∶C2H5OH∶H2O∶HF=1∶1.2∶2.66∶80∶1000∶0.7, and perfect AlPO4-5 large single crystals with the maximum length up to 2.0 and 0.31 mm transverse dimension have been prepared by crystallizing the mixture at 457 K for 48 h. Scanning Electron Microscopy (SEM) has been employed to observe the sizes and morphologies of the large single crystals of AlPO4-5. The structure of AlPO4-5 single crystal has been refined by the SMART 1000 single crystal diffractometer.     

微孔磷酸铝AIPO4-HDA的热分解过程研究

采用差热-热重-质谱(TG-DTA-MS)、粉末X射线衍射(XRD)、红外光谱(FTIR)和固体核磁(Solid-State-MAS-NMR)等技术详细地研究了微孔磷酸铝晶体AlPO4-HDA中模板剂的热分解过程.结果表明,该模板剂的热分解分3步进行:第一步是模板剂和无机骨架之间的部分氢键断裂;第二步为模板剂的Hof-mann降解反应和β-消除反应;第三步是残留积碳的氧化分解反应.固体MASNMR的研究结果表明,随着模板剂的脱出.无机骨架中铝和磷的配位状态发生了变化.     

Statics and dynamics of ethane molecules in AlPO(4)-5: a molecular dynamics simulation study.

From an experimental perspective, there has been disagreement among researchers on whether ethane would display single-file or normal diffusive behavior in the channels of AlPO(4)-5. Pulsed field gradient nuclear magnetic resonance measurements implied single-file diffusion, while quasielastic neutron scattering showed normal diffusion. In this paper we present the results of extensive classical molecular dynamics simulations of the diffusion of ethane molecules adsorbed in AlPO(4)-5. Our aim is to provide microscopic details of the static and dynamic properties of the adsorbed molecules in order to verify whether the conditions for the single-file regime can be achieved in a nondefective AlPO(4)-5 crystal structure.     

基于特征选择的决策树方法在磷酸铝AlPO4-5定向合成中的应用

分子筛类开放骨架材料的合成与结构关系研究对实现这类材料的定向合成起着至关重要的作用. 本文在建立开放骨架磷酸铝合成反应数据库的基础上, 提出了利用基于特征选择的决策树(C5.0)方法, 考察了不同反应条件(即各反应特征参数)对磷酸铝分子筛AlPO4-5生成的影响. 基于决策树模型, 利用8个反应特征参数,可以有效预测磷酸铝分子筛AlPO4-5的生成, 准确率达到88.18%, 接收者操作特性(ROC)曲线下面积(AUC)达到90%. 研究结果表明, 在众多的反应特征参数中, 有机模板剂的几何尺寸参数, 特别是模板剂的次长距离, 是影响AlPO4-5分子筛合成的重要因素.     

A combined experimental and theoretical evaluation of the structure of hydrated microporous aluminophosphate AlPO4-18

Water adsorption in the microporous aluminophosphate AlPO4-18 is studied by a combination of solid-state NMR, X-ray diffraction, and density functional theory calculations. The change of the framework structure upon hydration is moderate, and NMR gives local information on the environment of Al and P atoms. The structural distribution of water molecules in the channels has been explored by a combination of first-principle molecular dynamics simulations and of static geometry optimizations. Two starting points have been considered for the calculations. If the structure of the dehydrated aluminophosphate is used, the simulation result is not satisfactory with an incomplete hydration and no agreement with NMR results. Starting from a partial refinement of the aluminophosphate framework for the hydrated system, a structure with six tetrahedral and six octahedral Al atoms in the unit cell is obtained, involving twelve water molecules coordinated to Al atoms and twelve others in the channels, and in good agreement with experimental data.     

SAPO-18/SAPO-34共晶分子筛的合成及表征

以三乙胺(TEA)和N,N-二异丙基乙胺(DIEA)为双模板剂经恒温水热晶化法合成了SAPO-18(AEI结构)与SAPO-34(CHA结构)两相共生的SAPO分子筛. 考察了DIEA用量、 硅铝比及晶化时间等因素的影响, 并通过X射线衍射(XRD)、 扫描电子显微镜(SEM)和氨气程序升温脱附(NH₃-TPD)等手段对所得样品的晶相、 形貌和酸性进行了表征. 结果表明, 当n(DIEA)/n(Al₂O₃)=0.2, n(SiO₂)/n(Al₂O₃)=0.6, 晶化时间为4 d时, 得到形貌规整, 结晶度高且AEI/CHA结构比为74:26的共生相SAPO分子筛. 随着晶化时间的延长, SAPO-18在AEI/CHA共生相中所占比例逐渐上升, 表明SAPO-5, SAPO-34和SAPO-18三者中SAPO-18的热力学稳定性最高. 二甲醚制烯烃(DTO)催化性能测试结果表明, AEI/CHA共晶结构比为74/26的共生相分子筛具有较高的催化活性和双烯(C₂⁼+C₃⁼)选择性(84.29%), 同时积碳生成速率较慢.     

Syntheses and characterizations of heteroatom-containing open-framework aluminophosphates

Two heteroatom-containing open-framework aluminophosphates, (C(3)H(4)N(2))(2)FeAl(3)P(4)O(16) and (C(3)H(4)N(2))(2)CrAl(3)P(4)O(16) (denoted as MAPO-CJ50, M = Fe, Cr), have been synthesized by using imidazole as the template under solvothermal conditions. The structure of FeAPO-CJ50 is determined by single-crystal X-ray diffraction, and its analogous structure CrAPO-CJ50 is identified by powder X-ray diffraction. The 3-dimensional framework of MAPO-CJ50, constructed by MO(4)N(2) octahedra, AlO(4) tetrahedra, and PO(4) tetrahedra, contains interconnecting 10- and 8-ring channels. Imidazole molecules are coordinated with framework M(3+) ions and interact with each other through π-π stacking interactions in the channels. These two compounds show photoluminescent properties due to ligand-to-metal charge transfer. Magnetic measurements reveal that there are antiferromagnetic interactions between M(3+) ions in the frameworks of FeAPO-CJ50 and CrAPO-CJ50.     

VPI—5分子筛热相变转化成ALPO4—8的研究

VPI-5是具有十八元环超大孔道的磷酸铝分子筛,在加热过程中,随着孔道中的水分子的脱除,其骨架结构转化成具有十四元环孔道的AlPO_4-8分子筛。采用XRD及骨架结构模型计算等方法研究了这一相变过程,并对相变机理进行了探讨。     

气相转移法合成ZSM-5/SAPO-5复合分子筛

以磷酸、拟薄水铝石和硅溶胶为原料, 三乙胺为模板剂, 采用气相转移法合成了一系列ZSM-5/SAPO-5复合分子筛. 产物经X射线衍射、扫描电镜、X射线能量散射谱、红外光谱及N2 静态吸附法等手段对其进行了表征, 证明合成材料是以ZSM-5为核、SAPO-5为壳的双结构分子筛. 实验结果表明, 干胶制备条件及液相组成都影响复合分子筛的结晶. 晶化温度的提高和晶化时间的延长有利于分子筛结晶度的提高. VPT法可以减小SAPO-5和复合分子筛颗粒的直径, 改善SAPO-5在ZSM-5分子筛表面的分布. 重油裂化结果表明, 核壳结构复合分子筛对生成低碳烯烃的性能优于机械混合的样品.     

Template-Free Synthesis of AlPO 4 -H1 by Microwave Heating

Microwave heating enhanced the crystallization of aluminophosphate gels, and AlPO 4 -H1 was successfully obtained without using organic template reagents in a short reaction time. The use of amorphous aluminum hydroxide as an aluminum source and the addition of hydrochloric acid were found to be essentially important to obtain AlPO 4 -H1 as a single phase. Nitrogen and water adsorption properties were studied by measuring the adsorption isotherms.