高铝沸石的钙离子交换动力学研究

由于含磷洗涤剂的使用所带来的环境危害日益严重，高铝沸石作为洗涤剂助剂三聚磷酸钠的替代品已获得广泛的应用。作为洗涤剂助剂，沸石的Ca２＋、Mg２＋离子交换性能是影响其助洗效果的主要因素之一犤１，２犦。但目前对沸石的离子交换性质的研究多集中在离子交换平衡等温线的研究犤３～６犦，涉及沸石离子交换动力学的研究却鲜有报道。作为硬水的软化剂，洗涤剂用沸石对Ca２＋、Mg２＋离子的交换速率大小对洗涤效果的意义更为重要犤１犦。沸石的离子交换过程包括离子由溶液中扩散到沸石表面，再由沸石表面扩散到沸石孔道中的离子位等步骤…     

新型洗涤剂用沸石MAP的合成及其性能表征

在ＳｉＯ_２－Ａｌ_２Ｏ_３－Ｎａ_２Ｏ－Ｈ_２Ｏ体系中,采用加入晶种的方法水热合成出新型洗涤剂用沸石－ＭＡＰ。其硅铝比（Ｓｉ／Ａｌ）在 １．０７－１．１３之间,平均晶粒直径小于０．４μｍ,钙离子交换容量为２９０～３１３ ｍｇＣａＣＯ_３／ｇ（干沸石）,非离子表面活性剂的吸附量在 ８３～ １００ｇ ｏｉｌ／１００ｇ（沸石）之间。本文着重考察了影响合成 ＭＡＰ沸石的因素,确定了ＭＡＰ沸石会成的最佳范围,并对其物理化学性质进行了表征。     

三取代钨硅杂多配合物的导电性和磁性

合成了α－ＮａｍＨｎ［ＳｉＷ９Ｍ３（Ｈ２Ｏ）３Ｏ３７］·１６Ｈ２Ｏ（Ｍ＝Ｃｏ（Ⅱ），Ｎｉ（Ⅱ），Ｖ（Ⅴ）杂多配合物），通过ＩＣＰ，ＩＲ，ＵＶ，ＴＧ－ＤＴＡ，ＸＰＳ，ＥＰＲ，极谱等手段进行了表征．配合物在室温下的电导率σ值达１×１０－３Ｓ·ｃｍ－１，３４３Ｋ时可达１×１０－２Ｓ·ｃｍ－１，是有实用化前景的新型固体电解质．变温磁化率结果表明α－Ｎａ１０［ＳｉＷ９Ｃｏ３（Ｈ２Ｏ）３Ｏ３７］·１６Ｈ２Ｏ和α－Ｎａ１０［ＳｉＷ９Ｎｉ３（Ｈ２Ｏ）３Ｏ３７］·１６Ｈ２Ｏ具有反铁磁性．     

As-V-O簇合物对乙苯选择氧化反应的催化活性

通过水热方法合成了簇合物［Ｎ（ＣＨ３）４］４［Ａｓ８Ｖ１４Ｏ４２（８Ｈ２Ｏ）］及其相近的同多及杂多钒氧簇Ｋ６Ｖ１０Ｏ２８·９Ｈ２Ｏ，ＮａＫＶ２Ｏ６，（Ｈ２Ｅｎ）０．５Ｖ２Ｏ５，（Ｈ２Ｅｎ）３（ＶＯ）９（ＰＯ４）８，Ｎａ３ＶＯ（ＨＰＯ４）（ＰＯ４）·Ｈ２Ｏ．运用ＸＲＤ和ＩＲ等手段表征了［Ｎ（ＣＨ３）４］４［Ａｓ８Ｖ１４Ｏ４２（８Ｈ２Ｏ）］的结构．该类化合物对于催化乙苯过氧化氢选择氧化制苯乙酮具有较高的催化活性．通过比较含钒与不含钒化合物的活性情况，讨论了催化氧化的活性中心．     

在水蒸气气氛中合成沸石分子筛及其特性

无定型硅铝凝胶－Ｎａ２Ｏ－Ａｌ２Ｏ３－ＳｉＯ２－Ｈ２Ｏ在水蒸气相中可以晶化合成出ＬＴＡ，ＦＡＵ和ＭＯＲ沸石晶体。本文重点研究了ＭＯＲ沸石的晶化条件和物理化学特性。     

四苯氧基酞菁镁、锰、铝和锌的合成和性质

合成了新的酞菁配合物４，４，４，４－四苯氧基酞菁镁［ＴＰｈＯＰｃＭｇ（Ⅱ）］，锰［ＴＰｈＯＰｃＭｎ（Ⅱ）Ａｃ］，铝［ＴＰｈＯＰｃＡｌ（Ⅲ）Ｃｌ］，锌［ＴＰｈＯＰｃＺｎ（Ⅱ）］测定了它们的ＩＲ，ＵＶ－Ｖｉｓ光谱，在ＤＭＦ中的氧化还原半波电势（Ｅ１／２），电子转移速度常数，在乙腈中的荧光性质及锰的配合物在不同电位下的光谱变化情况。     

合成沸石用溶液组分的中间控制分析

沸石是天然和合成水合钠 (钾、钙、钡 )铝硅酸盐矿物的通称。合成沸石基于铝硅酸盐外配位层和沸石分子中碱 (碱土 )金属、铝、硅之间摩尔比的不同以及合成条件的差异 ,而有多种型号。其中常用的Ｎａ Ａｌ Ｓｉ结构框架的就有 4Ａ、 13Ｘ、Ｙ、丝光沸石等类型[1] ,而 4Ａ沸石经ＫＣｌ或ＣａＣｌ2 部分交换处理后 ,生成 3Ａ (Ｋ Ｎａ Ａｌ Ｓｉ)或 5Ａ (Ｃａ Ｎａ Ａｌ Ｓｉ)沸石 ;13Ｘ型 (Ｎａ Ａｌ Ｓｉ)经ＣａＣｌ2 交换后生成10Ｘ (Ｃａ Ｎａ Ａｌ Ｓｉ)沸石。因此 ,Ｎａ Ａｌ Ｓｉ型合成沸石是制取其它合成沸石的基础。本文介绍的合成沸…     

氟氯有机化合物对HZSM-5分子筛改性过程中氟和氯的作用

利用ＸＲＤ，ＭＡＳ，ＮＭＲ，ＩＲ和ＸＰＳ等手段研究了ＣＦ４－ｎＣｌｎ改性的ＨＺＳＭ－５分子筛的体相和表面结构的变化。结果表明，改性过程中Ｆ和Ｃｌ均能使ＨＺＳＭ－５脱铝和脱硅。Ｃｌ可以使沸石骨架ＳｉＯ２／Ａｌ２Ｏ３升高，而Ｆ除使沸石骨架脱铝外，还会极化其晶格。Ｆ比Ｃｌ更容易在沸石表面富集。Ｆ和Ｃｌ是通过取代Ｏ或ＯＨ与沸石表面Ｓｉ或Ａｌ作用的。改性后的沸石表面有数种含氟表面物种存在。     

以拟薄水铝石为铝源合成的β沸石的表征和催化性能(英文)

考察了以拟薄水铝石为铝源、固体硅胶为硅源、四乙基氢氧化铵为模板剂时不同晶化混合液ＳｉＯ２／Ａｌ２Ｏ３比和不同晶化温度对β沸石合成的影响。ＸＲＤ、ＴＧＡ、ＩＣＰ及ＳＥＭ研究结果表明,在晶化混合液ＳｉＯ２／Ａｌ２Ｏ３比为２０至５０之间、晶化温度为１４０℃～１６０℃范围内能合成出高结晶度的β沸石,且β沸石硅铝比与晶化混合液硅铝比呈良好的线性关系：ＴＧＡ总失重量随β沸石硅铝比增加而增加,晶化温度对β沸石的晶粒度没有明显影响。此外,所制备的Ｈβ沸石对甲苯与Ｃ９芳烃歧化和烷基转移反应具有良好的催化性能。     

杂原子B—ZSM—35沸石的干法合成,表征及CO＋H2反应性能的研究

首次利用吸附态模板剂在Ｎａ２Ｏ－ＳｉＯ２－Ｂ２Ｏ３－ＤＥＡ干粉体系中合成了杂原子Ｂ－ＳＺＭ－３５沸石，ＸＲＤ，ＳＥＭ，ＩＲ，及ＣＯ加氢反应研究了其物理化学特性。结果表明，Ｂ原子同晶取代Ａｌ原子进入ＺＳＭ－３５沸石骨加。     

Retaining60Co2+ ions from residual water on zeolites

The ion exchange between⁶⁰Co²⁺ ions contained in residual radioactive water and zeolites of the NaA, NaX and CaA types was studied. The more advanced retaining of⁶⁰Co²⁺ ions occurs for the NaA zeolite with the higher exchange capacity, as compared to NaX. With the CaA zeolite, a very weak ion exchange with⁶⁰Co²⁺ ions was observed.     

Study of intracrystalline diffusion in zeolites 6. Comparison of the results obtained by the method of densitometry of light and the adsorption method

The use of the method of densitometry of light passing through a layer of zeolite crystals permits determining the limiting stage of diffusion during adsorption by zeolites. Diffusion in transport pores and external heat exchange play the basic role in adsorption of benzene by NaX zeolite, while diffusion in crystals is the determining mechanism of transport in adsorption of water by NaA and NaX zeolites. The diffusion coefficients of water in NaX zeolite have an order of magnitude of 10^–17 m²/sec and increase with an increase in the degree of filling. An explanation for the anomalous behavior of the kinetic adsorption curve for brief times of adsorption of water by zeolite is proposed.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1224–1228, June, 1990.     

Heats of immersion of some ion-exchanged A and X zeolites of divalent cations

Heats of immersion in water (integral heats of hydration) of anhydrous zeolites NaA, CdA, ZnA, CoA, NaX, CdX, ZnX, CoX and NiX have been determined calorimetrically at 25°C. Sodium in NaA and NaX has been replaced by divalent cations to the extent of 70–100% . The data are correlated to the size of the cations and to the standard enthalpy changes of the corresponding ion-exchanged equilibria. The latter values are analysed in terms of three processes: hydration of ions in solution, hydration of zeolites, and electrostatic binding energy of cations to the zeolite framework.     

Gibbs ensemble Monte Carlo simulation of supercritical CO2 adsorption on NaA and NaX zeolites

Adsorption of supercritical carbon dioxide on two kinds of zeolites with identical chemical composition but different pore structure (NaA and NaX) was studied using the Gibbs ensemble Monte Carlo simulation. The model frameworks for the two zeolites with SiAl ratio being unity have been chosen as the solid structures in the simulation. The adsorption behaviors of supercritical CO2 on the NaA and NaX zeolites, based on the adsorption isotherms and isosteric heats of adsorption, were discussed in detail and were compared with the available experimental results. A good agreement between the simulated and experimental results is obtained for both the adsorbed amount and the bulk phase density. The intermediate configurational snapshots and the radial distribution functions between zeolite and adsorbed CO2 molecules were collected in order to investigate the preferable adsorption locations and the confined structure behavior of CO2. The structure behaviors of the adsorbed CO2 molecules show various performances, as compared with the bulk phase, due to the confined effect in the zeolite pores.     

Chromium removal from water using LTA zeolites: effect of pH

The effect of pH changes on the ability of the synthetic zeolite NaA to remove Cr(3+) from water by ion exchange was investigated. The exchange rate was improved by working near neutrality. Despite of the occurrence of simultaneous adsorption, precipitation or cation exchange phenomena, spectroscopic analyses of samples taken at different contact times suggested the presence of an unique chromium environment in the solid phase. The increase in pH observed during the ion exchange favored polymerization-precipitation of chromium species present in solution, which, in turn, improved the metal removal capacity of zeolite NaA above the values expected for a pure cationic exchange reaction.     

碱金属卤化物与NaA分子筛之间的固态离子交换反应

在低于碱金属卤化物熔点的温度下热处理碱金属卤化物和脱水NaA分子筛干混样品时,一部分分散到分子筛内孔的金属离子能够与脱水分子筛进行程度不同的固态离子交换反应,生成的非挥发性NaCl产物将扩散到分子筛笼外单独结晶或剩余的原卤化物形成溶体.热处理温度愈度,离子交换度愈大;在一定温度下热处理干混样品,存在最大离子交换度.     

In situ SAXS/WAXS of zeolite microwave synthesis: NaY, NaA, and beta zeolites.

A custom waveguide apparatus is constructed to study the microwave synthesis of zeolites by in situ small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS). The WR-284 waveguide is used to heat precursor solutions using microwaves at a frequency of 2.45 GHz. The reaction vessels are designed to include sections of thin-walled glass, which permit X-rays to pass through the precursor solutions with minimal attenuation. Slots were machined into the waveguide to provide windows for X-ray energy to enter and scatter from solutions during microwave heating. The synthesis of zeolites with conventional heating is also studied using X-ray scattering in the same reactor. SAXS studies show that the crystallization of beta zeolite and NaY zeolite is preceded by a reorganization of nanosized particles in their precursor solutions or gels. The evolution of these particles during the nucleation and crystallization stages of zeolite formation depends on the properties of the precursor solution. The synthesis of NaA and NaX zeolites and sodalite from a single zeolite precursor is studied by microwave and conventional heating. Microwave heating shifts the selectivity of this synthesis in favor of NaA and NaX over sodalite; conventional heating leads to the formation of sodalite for synthesis from the same precursor. The use of microwave heating also led to a more rapid onset of NaA zeolite product crystallization compared to conventional heating. Pulsed and continuous microwave heating are compared for zeolite synthesis. The resulting rates of formation of the zeolite products, and the relative amounts of the products determined from the WAXS spectra, are similar when either pulsed or continuous microwave heating is applied in the reactor while maintaining the same synthesis temperature. The consequences of these results in terms of zeolite synthesis are discussed.     

Effect of zeolite properties on ground-state and triplet-triplet absorption, prompt and oxygen induced delayed fluorescence of tetraphenylporphyrin at gas/solid interface

The ground-state and transient absorption, prompt and delayed fluorescence of tetraphenylporphyrin (TPP) adsorbed onto the external surface of different zeolites was monitored using diffuse-reflectance steady-state and laser flash photolysis. The delayed fluorescence (DF) of TPP detected in the presence of O2 is attributed to the energy transfer from 3TPP to 3O2 to form 1O2 and subsequent energy transfer from 1O2 to some other 3TPP within the organised molecular ensembles on the zeolite surface. The spectroscopic and kinetic parameters, namely the yield of DF (2-20% relative to prompt fluorescence), depend on the zeolite properties: the observed differences were correlated with the acid-base properties of the two zeolite series studied in this work (KA, NaA, CaA) and (NaA, NaX, NaY).     

Synthesis of NaX and NaY Zeolites from Tunisian Kaolinite as Base Catalysts: An Investigation of Knoevenagel Condensation

The synthesis of Faujasite‐type zeolites with high purity has been successfully performed from Tunisian kaolinite and the effects of different crystallization parameters on the final products were widely investigated. The alkaline fusion of kaolinite followed by hydrothermal treatment lead to zeolite NaX synthesis whereas the classic hydrothermal transformation of metakaolinite produces NaY zeolite. The results show that an increase in the synthesis temperature and time has improved the crystallization process of the zeolite NaX whereas the SiO₂/Al₂O₃ and the Na₂O/SiO₂ molar ratios were the key parameters to obtain a pure zeolite NaY. The highest specific surface areas obtained with the optimal crystallization conditions were 554 m2 g^?1 and 592 m2 g^?1 for respectively NaX and NaY zeolites. The basic properties of NaX and NaY zeolites were explored in the Knoevenagel condensation of benzaldehyde with ethyl cyanoacetate at 140 °C as a test reaction in the absence of solvent. The influence of ion exchange with cesium cation on the catalytic activity of prepared catalysts was also investigated. It was found that the NaX provided higher activity than that of NaY catalyst due to its lower Si/Al ratio whereas a cesium exchange conferred higher basicity to the prepared Na‐faujasite.