Sorption and Diffusion of p-Xylene and o-Xylene in Aluminophosphate Molecular Sieve AlPO4-11

This paper presents experimental results for equilibrium and diffusion of C₈ aromatics in laboratory synthesised crystals of AlPO₄-11. The samples were prepared by the hydrothermal method, starting from pseudobohemite (CONDEA), 85% phosphoric acid, water and di-isopropilamine as organic template. Adsorption and diffusion data were obtained mainly by gravimetry at temperatures between 60–100°C. Saturation capacities were found in the range of 4 wt%. Equilibrium constants were estimated using virial plots yielding heats of adsorption between 10–12 Kcal/mol at low coverage. Intracrystalline diffusivities at higher temperatures (150–180°C) were also measured, using the Zero-Length-Column (ZLC) method. Diffusivities from both methods (gravimetric and ZLC) agreed reasonably well and followed a typical Arrhenius behaviour, with low activation energy (ca. 7 Kcal/mol).     

磷酸铝分子筛AlPO4-5,AlPO4-11及AlPO4-20的合成与性能

以有机胺或季胺盐作为模板剂,用水热法合成了AlPO₄-5,AlPO₄-11及AlPO₄-20分子筛。所得样品用X-射线衍射图及红外先谱图进行表征。差热分析表明这些样品直到～950℃无结构破坏,所测样品的吸附等温线表明在AlPO₄-5及AlPO₄-11上水的吸附容量大于碳氢化合物。     

二甲苯在AlPO4-5分子筛中吸附的分子模拟研究

采用巨正则蒙特卡罗法(GCMC)研究了二甲苯异构体在AlPO4-5中的吸附，得到了有关吸附平衡常数、吸附热、吸附等温线及吸附位等信息．结果表明，在303K时，邻二甲苯的吸附量高于其它异构体；而在523和573K时，对二甲苯的吸附量最高．低吸附量时二甲苯的平均势能基本不发生变化，而高吸附量时二甲苯的平均势能随着吸附量增加而降低，尤其邻二甲苯的平均势能变化更加明显．由此对二甲苯各异构体在AlPO4-5中的吸附量差别以及它们在分子筛中的排列方式进行了讨论．     

AlPO4-5分子筛中二氯苯吸附的分子模拟

采用巨正则蒙特卡罗法（GCMC）研究了二氯苯异构体在AlPO4-5中的吸附，得到了有关吸附热、吸附等温线及吸附位等信息.结果表明，在373 K时，邻二氯苯的吸附量高于对二氯苯；而在523和573 K时，对二氯苯的吸附量高于邻二氯苯.二氯苯的平均势能随着吸附量的增加而降低.讨论了二氯苯异构体在AlPO4-5中的吸附量与它们在分子筛中的排列方式的关系.     

磷酸铝分子筛骨架结构及其稳定性的模拟计算

采用晶格能极小化技术模拟计算了块磷铝矿和１２种磷酸铝分子筛的骨架晶格，包括ＡｌＰＯ４－３１，ＡｌＰＯ４－１１，ＡｌＰＯ４－８，ＡｌＰＯ４－５，ＡｌＰＯ４－２０，ＡｌＰＯ４－１６，ＡｌＰＯ４－１７，ＡｌＰＯ４－３５，ＡｌＰＯ４－５２，ＡｌＰＯ４－１８和ＶＰＩ－５，预测了它们的几何构型和晶格能，讨论了计算晶格能和骨架结构间的关系，结果表明，随着骨架密度的增大，晶格能呈降低趋势，骨架的相对稳定性增强。     

Sorption of C6 Alkanes in Aluminophosphate Molecular Sieve, AlPO4-5

Sorption of C₆ alkanes viz.,n-hexane, 2-methylpentane, 2,2-dimethyl butane, 2,3-dimethyl butane, cyclohexane and methyl cyclopentane in AlPO₄-5 is studied and sorption capacity and thermodynamic parameters (H⁰, H, G, S and S_a) at various sorption coverage for these sorbates have been estimated. The initial heat of sorption (H⁰) is found to increase with the degree of branching in the alkane chain. The sorbate-sorbate interactions are found to be more prominent during the sorption of doubly branched alkanes and cyclic alkanes and a higher sorption capacity has been observed for cyclic alkanes. Based on the results obtained, a packing model has been proposed for various C₆ alkanes inside the AlPO₄-5 channel.     

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.     

Synthesis and Characterization of Magnesium Substituted Aluminophosphate Molecular Sieves with AEL Structure

MAPO-11 molecular sieves were synthesized by hydrothermal methods. The influence of precursor of magnesium, Mg/Al ratio, synthesis temperature, synthesis time and the type of template on the formation and properties of MAPO-11 molecular sieves was examined. The samples were characterized by the techniques of X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric/differential thermogravimetric analysis (TG-DGA), etc. The results show that the shape and size of crystal were influenced by the precursor of Mg, the Mg/Al ratio and the type of template, and the TG-DGA analysis shows that MAPO-11 molecular sieves as-synthesized have poor thermal stability.     

磷铝分子筛的制备与应用进展

综述了近三年来磷铝分子筛最新的研究进展,包括磷铝分子筛水热法、溶剂热、离子热制备的合成进展,相比传统方式的制备,制备方法有所创新,条件有所优化,成本有所降低,制备出来的结构和形貌也与以往不同。然后分类总结了磷铝分子筛作为催化剂应用,相比以往磷铝分子筛可催化的化学反应变多,制备出来的改性或介孔磷铝分子筛的催化活性变强和使用寿命边长,最后对其的发展前景作了评述。     

Gel Chemistry in Synthesis of AIPO4 Molecular Sieves

The chemistry of ternary systems, Al₂O³-P₂O₅-H₂O, particularly on addition of an acid or an amine as fourth component was investigated with ³¹P and ²⁷Al NMR spectroscopy.     

新型磷酸铝分子筛AlPO_4-CJ_2的合成与结构研究

在Al_2O_3-P_2O_5-六次甲基四胺-H_2O体系中,水热合成出新型磷酸铝分子筛(AlPO_4-CJ_2),培养了单晶,经多晶X射线衍射、四圆单晶结构测定及红外光谱研究证明,AlPO_4-CJ_2具有空旷的骨架结构,沿(100)和(001)方向具有8元环孔道,骨架中Al原子以AlO_5(三角双锥)和AlO_5F(扭曲八面体)形式存在,水分子氧的桥联产生Al—O—Al连接模式。     

微波辐射条件下混合溶剂体系中AlPO4-5分子筛的晶貌控制

在微波辐射条件下于混合溶剂体系中实现了AlPO4-5分子筛晶体的形貌控制. 实验结果表明, AlPO4-5分子筛晶体的长径比(c/a)随体系中乙二醇与水体积比的增大而减小, 其长径比可以在1.7~6.3之间调变. 当在体系中加入晶种诱导时, 产物晶粒的大小随加入晶种量的增加和诱导时间的延长而明显减小. 在正丁醇与水的混合体系中, 当正丁醇与水的体积比达到5∶1时, 可以形成哑铃形的特殊晶貌.     

H（Mg,Co）AlPO4—5杂原子分子筛的酸性质测定

以红外光谱和程序升温脱附法研究了H(Mg,Co)AlPO_4-5分子筛的酸性,样品红外谱图中的3820和3680cm~(-1)谱峰分别归属于v_(Al—OH)和v_(p—OH),而3660～3568cm~(-1)谱峰则分别归属于HMgAlPO_4-5和HCoAlPO_4-5分子筛的M(OH)P(M=Mg,Co)基团的振动,酸强度顺序为:Co(OH)P>Mg(OH)P>P(OH)>Al(OH),吡啶吸附的红外光谱揭示,H(Mg,Co)AlPO_4-5分子筛具有较高酸强度的B酸和L酸中心。NH_3-TPD表明分子筛的酸强度顺序为H(Co)AlPO_4-5>H(Mg)AlPO_4-5>>AlPO_4-5。     

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.     

AlPO4-5分子筛模板剂的量子化学计算

以23种有机分子作为模板剂用于AlPO₄-5分子筛的合成,利用分子图形技术研究这些有机分子的形状和尺寸,采用量子化学PM3方法研究这些有机分子的电子性质,计算它们与AlPO₄-5分子筛骨架模型簇之间的相互作用能。结果表明,量子化学计算数据可以作为寻找合成AlPO₄-5分子筛新型模板剂时的重要参考依据。     

Synthesis and Characterization of AlPO4-11 and MAPO-11 Single Crystals

The preparation of two types of molecular sieves AlPO4-11 and MAPO-11 is reported. The particle size of the latter is hundreds of microns, about 10 times larger than that of the former. The XRD, IR and DTA spectra have demonstrated that magnesium has been introduced into the framework of AlPO4-11. The successful preparation of large single crystal of MAPO-11 will open up a new area for the preparation of large molecular sieves crystals in the future. The large MAPO-11 crystal compound is a promising host for the host-guest assembly of composite materials.     

Effect of Pore Structure and Acidity of Molecular Sieves on C_8 Aromatic Performance

我们成功合成了几种具有典型结构的分子筛,并考察了这些分子筛的孔结构、酸性以及在碳八芳烃异构化反应中的反应性能.结果表明,对于碳八芳烃异构化反应,孔结构和酸性起着重要作用,孔结构决定了反应的类型或方式,而酸性质与反应的活性和选择性密切相关,一个好的碳八芳烃异构化催化剂要同时具备适宜的孔道结构和酸性.     

Sorption of Benzene in CoAlPO4-5 Molecular Sieves

The sorption isotherms of benzene in CoAlPO₄-5 at temperatures of 323–399 K were measured by the gravimetric technique. The sorption capacity and isosteric heat were estimated and interpreted on the basis of the pore topologies of the molecular sieves. The isotherms followed the typical Type-I shape, and could be well fitted with Langmuir and Dubinin-Radushkevich equations. The initial heats of sorption at zero coverage could be well explained by the surface curvature model. The isosteric heats of sorption varied with the coverage, which may suggest a shift of molecular packing manner in the sorbed phase.     

MgAPO-11 分子筛的合成、表征及其催化正己烷裂解反应的动力学研究

以二异丙基胺为有机模板剂,采用静态水热法合成了具有不同镁含量的镁铝磷酸盐分子筛MgAPO-11,并利用X射线衍射、扫描电子显微镜、傅里叶变换红外光谱、魔角旋转核磁共振和电感耦合等离子体原子发射光谱等方法对其进行表征.当0相似文献   

磷酸铝分子筛AlPO4-12的合成与性能研究

用乙二胺作模报剂,在水热体系中合成了磷酸铝分子筛ＡＩＰＯ４－１２,考察了反应混合物的初始ＰＨ值和乙二胺用量对产物结晶相的影响,产品的化学组成与文献值吻合。用ＸＲＤ、ＳＥＭ、ＩＲ、ＤＴＡ、化学分析和吸附等方法,对样品进行了表征及物化性能的研究,用丙酸与正丁醇的酯化为典型反应,考究了ＡＩＰＯ４－１２分子筛的催化性能,实验结果表明,ＡＩＰＯ４－１２具有良好的吸附性能、很高的热稳定性（骨架倒塌温度为９９７