水热条件下坡缕石在NaOH溶液中的行为及结构变化

分别用1,2和3 mol·L^-1的NaOH溶液,在不同的温度条件下对坡缕石进行了侵蚀实验。对反应后的固相产物进行了XRD和SEM分析,对浸出液中的金属阳离子进行了原子吸收光谱分析。讨论了反应温度和碱溶液浓度对碱溶后产物的影响。XRD和SEM结果表明,c_NaOH≤2 mol·L^-1时,坡缕石经碱溶液侵蚀后,可以生成蒙脱石和方沸石,其中反应温度的升高有利于方沸石的形成,碱溶液浓度的升高有利于蒙脱石的形成。当碱溶液浓度达到3 mol·L^-1,反应温度为200 ℃时,最终产物为SiO₂。浸出液的定量分析结果显示,坡缕石与碱溶液的反应过程中,Na⁺对八面体阳离子的置换具有选择性,置换顺序为：Al³⁺＞Fe³⁺(Fe²⁺)＞Mg²⁺。     

V-TiO2/凹凸棒石复合光催化材料的制备与研究

以凹凸棒石为载体,钛酸四丁酯为前驱体,采用溶胶-凝胶法制备了V-TiO2/凹凸棒石复合光催化材料.通过X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电镜(TEM)以及紫外-可见漫反射光谱(UV-Vis DRS)对材料的晶体结构、微观形貌及光学性能进行了表征.研究表明:凹凸棒石显著提高了材料的吸附能力,有效抑制了催化剂纳米粒子的团聚;以10 mg/L的罗丹明B溶液为目标降解物,研究了不同热处理温度下制备的V-TiO2/凹凸棒石(V掺量0.5;)在模拟太阳光下的降解效果,结果表明:400℃下煅烧2h的样品性能最优;与其它对照材料相比,V-TiO2/凹凸棒石(V掺量0.5;)复合光催化材料性能更优.     

Effect of Solvents Treatment on Microstructure and Dispersion Properties of Palygorskite

Palygorskite was dispersed by various organic solvents and water, and the effects of solvent types on its microstructure, dispersion degree, and colloidal properties were investigated by infrared spectroscopy (IR), x-ray diffraction (XRD), and nitrogen adsorption-desorption isotherm (BET), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and rheological analyses. It was found that dimethyl sulfoxide and dimethyl formamide molecules may attach onto the surface of palygorskite and cause a complete disappearance of micropores. Solvent parameters govern the dispersion degree of palygorskite, and dimethyl sulfoxide and dimethyl formamide are good solvents to disperse palygorskite aggregates in contrast to ethanol and isopropanol. Colloidal stability and rheological tests suggested dimethyl sulfoxide-dispersed palygorskite can form more stable suspension with higher shear stress and modulus, but isopropanol-dispersed palygorskite may rapidly subside in suspension and show poor colloidal properties.     

硅烷化凹凸棒石负载H5PMo10V2O40催化合成苯甲醛乙二醇缩醛

以酸活化的凹凸棒石（Pa）为原料,用3-氨丙基三乙氧基硅烷（APTES）嫁接法制备了以3-氨丙基三乙氧基硅烷（3-aminopropyl—triethoxysilane,APTES）硅烷化凹凸棒石（PaAms）为载体负载Keggin型H5PMo10V2O40杂多酸催化剂（PMoV／PaAPTES）,并用红外光谱分析、X...     

凹凸棒石负载的Cu-Mn-Ce催化剂上甲苯氧化反应性能

采用浸渍法制备了凹凸棒石(PG)负载Cu-Mn-Ce催化剂,运用X射线衍射、透射电镜和H2程序升温还原等方法对催化剂进行了表征,并将催化剂用于氧化降解甲苯反应中,考察了不同活性组分、Ce添加量以及催化剂焙烧温度对催化剂活性的影响,探讨了催化剂中活性组分的存在形式及与催化氧化活性的关联.结果表明,催化剂中Cu,Mn和Ce...     

生物质焦油组分甲苯在镍/凹凸棒石上的二氧化碳催化重整

 以大比表面积的天然纳米矿物材料凹凸棒石 (PG) 为载体, 采用等体积浸渍法制备了 Ni/PG 催化剂. 运用 X 射线衍射、透射电镜和 CO₂ 程序升温脱附对 Ni/PG 催化剂进行了表征, 并用于以甲苯为生物质焦油模型化合物的 CO₂ 催化重整反应. 考察了反应温度、CO₂ 浓度以及催化剂中 Ni 负载量对甲苯与 CO₂ 重整性能的影响. 结果表明, 吸附在催化剂表面的 CO₂ 存在三个脱附峰, 其中高温脱附 CO₂ 与反应密切相关; 随着 CO₂ 浓度、Ni 负载量和反应温度的增加, 甲苯转化率和 H₂ 产率升高. 在 800 ^oC, CO₂/PhCH₃ 摩尔比为 0.2~0.26 时, 甲苯转化率达最高; 而在 CO₂/PhCH₃ 摩尔比为 0.2 时, H₂ 产率最高. 催化剂上积炭量随 CO₂ 浓度的增加和反应温度的升高而显著降低.     

Some thermal characteristics of a mineral mixture of palygorskite,metahalloysite, magnesite and dolomite

An industrial raw material taken from Sivrihisar (Eskişehir, Turkey) region was heat-treated at different temperatures in the range of 100–1000°C for 2 h. The volumetric percentage of the particles having a diameter below 2 μm after staying in an aqueous suspension of the material was determined as 67% by the particle size distribution analysis. The mineralogical composition of the material was obtained as mass% of 32% palygorskite, 10% metahalloysite, 35% magnesite, 20% dolomite and 3% interparticle water by using the acid treatment, X-ray diffraction and thermal analysis (TG, DTA) data. The temperature ranges were determined for the endothermic dehydrations for the interparticle water as 25–140°C, for the zeolitic water as 140–320°C, and for the bound water as 320–480°C, in the palygorskite. The temperature range for the endothermic dehydroxylation and exothermic recrystalization of the palygorskite is 780–840°C. The temperature range for the endothermic dehydroxylation of the metahalloysite and calcinations of magnesite are coincided at 480–600°C. Dolomite calcined in the temperature range of 600–1000°C by two steps. The zig-zag changes in the specific surface area (S/m² g⁻¹) and specific micro and mesopore volume (V/cm³ g⁻¹) as the temperature increases were discussed according to the dehydrations in the palygorkskite, dehydroxylation of palygorskite and metahalloysite, and calcinations in magnesite and dolomite.     

Stabilization of aqueous suspensions of palygorskite by thermal vapour pressure shock explosion (TSE) treatment

A device was constructed in which a clay suspension is hermetically heated at 220°C for a few minutes. This thermal treatment is accompanied by a pressure increase in the cell. Once the valve is opened, there is a fast release of the pressure inside the cell and a sudden evolution of the interparticle water. This shock leads to a quasi explosion of the clay particle. This technique was named thermal vapour pressure shock explosion (TSE). The effect of TSE treatment on the properties of palygorskite suspensions was investigated. Palygorskite suspensions in water are rather unstable and particles smaller than 3 μm in size are not found before a TSE treatment. Stabilization of the suspension can be obtained by TSE treatments and/or by using a dispersing agent such as pyrophosphate, or both. As a result of TSE treatments smaller particles are obtained, the dispersiveness of the particles is improved and electrophoretic mobility is increased. Electron microscopy scans showed that the aggregates of needles which form the palygorskite fibres, disintegrate to separated thin needles as a result of the TSE treatment. Dedicated to Professor Lisa Heller-Kallai on the occasion of her 65^th birthday