SO42-改性的锆交联黏土固体酸催化合成柠檬酸三丁酯

制备了SO4 2 -改性的锆交联黏土固体酸催化剂 (A) ,用于柠檬酸 (B)和正丁醇 (C)的酯化反应 ,与浓硫酸 ,钠基膨润土和锆交联黏土作催化剂的情况相比 ,SO4 2 -改性的锆交联黏土作催化剂时柠檬酸的转化率和产物的纯度更高。同时考察了催化剂用量w(A)、酸醇量比n(B)∶n(C)、反应时间 (t)、反应温度 (θ)对其催化合成柠檬酸三丁酯 (D)的影响 ,并对合成的产物进行红外光谱分析及气相色谱分析。实验结果表明 :SO4 2 -改性的锆交联黏土固体酸催化柠檬酸与正丁醇的酯化反应的最佳反应条件为 :反应温度为 15 0℃ ,n(B)∶n(C) =1∶4,反应时间 3 .5h ,催化剂用量占反应投料总质量的百分比w(A) =1.2 % ,柠檬酸的转化率达 96 .6 0 % ,反应产物柠檬酸三丁酯的质量分数w(D) >99 0 0 %     

交联粘土合成及其在C3H6选择性催化还原NOx中的应用研究

用不同的交联剂溶液与钠基土进行交联反应,合成了不同交联粘土(Al-PILC、Zr-PILC、Ti-PILC).以合成的交联粘土作为载体负载Cu及其它金属活性组分,考察了富氧条件下C3H6选择性还原NO反应的催化活性.与Cu/Al-PILC、Cu/Zr-PILC相比,Cu/Ti-PILC显示了很好的低温活性和较宽的活性温度范围.Cu的负载方法影响催化剂活性, 浸渍法制备的催化剂比离子交换法制备的催化剂活性好.用N2吸附等温线、孔径分布以及漫反射红外光谱研究了交联过程及活性组分的负载对交联粘土结构的影响.钠基土经TiO2交联柱撑后,孔结构和孔径分布有了很大的改变,比表面积和孔容大幅增加.负载活性组分Cu没有改变Ti-PILC的孔结构,只是减少了比表面和孔容.漫反射红外光谱研究发现,经TiO2柱撑后,粘土结构羟基减少,交联剂与粘土结构羟基发生了交联作用.     

SO42-改性的锆交联黏土固体酸催化合成柠檬酸三丁酯

制备了SO42-改性的锆交联黏土固体酸催化剂(A),用于柠檬酸(B)和正丁醇(C)的酯化反应,与浓硫酸,钠基膨润土和锆交联黏土作催化剂的情况相比,SO42-改性的锆交联黏土作催化剂时柠檬酸的转化率和产物的纯度更高.同时考察了催化剂用量w(A)、酸醇量比n(B)∶n(C)、反应时间(t)、反应温度(θ)对其催化合成柠檬酸三丁酯(D)的影响,并对合成的产物进行红外光谱分析及气相色谱分析.实验结果表明SO42-改性的锆交联黏土固体酸催化柠檬酸与正丁醇的酯化反应的最佳反应条件为反应温度为150 ℃,n(B)∶n(C) = 1∶4,反应时间3.5 h,催化剂用量占反应投料总质量的百分比w(A) =1.2%,柠檬酸的转化率达96.60%,反应产物柠檬酸三丁酯的质量分数w(D)>99.00%.     

羟基锆交联累托石的制备及性能研究

以钠化累托石为原料进行改性 ,制备出羟基锆交联累托石 ,并研究了羟基锆交联累托石对COD模拟废水的吸附性能。试验结果表明 ,该交联剂可由 0 2mol/L的ZrOCl2 ·8H2 O溶液在 85℃下回流 1 2h制得 ;然后将其添加到累托石的悬浮液 (质量分数为 6 % )内 ,在 6 5℃下 ,再搅拌 2 5h ;生成物的BET法表面积为 9 2 5 0m2 g。     

锆基柱撑膨润土的水热法制备及其MTO催化性能

以钠基膨润土为原料,ZrOCl2.8H2O为柱化剂的锆源,采用水热合成法制备了锆基柱撑膨润土（Zr-PILM）,结合XRD对产物进行表征,探讨了锆/土比和焙烧温度对甲醇制备低碳烯烃（Methane-to-Olefin,简称MTO）的影响。结果表明：Zr-PILM的d001值随着锆/土比的增加而增大,锆/土比从15mmol/g增加为30mmol/g时,d001值仅增大了0.03nm,说明膨润土可交换容积已基本达到饱和;经过300℃焙烧其d001可达2.16nm;对比同样经过500℃焙烧的柱撑前后膨润土,Zr-PILM的d001值由柱撑前的0.96nm变为2.01nm,说明其保留了层间结构,热稳定性提高;Zr-PILM催化MTO反应可使甲醇转化率达到95.01%,低碳烯烃的选择性达到68.24%。     

有机修饰钛交联粘土对染料废水的脱色性能研究

以甲基橙溶液为模拟染料废水,研究了十六烷基三甲基溴化铵修饰的钛交联粘土对染料废水的脱色性能。结果表明:有机修饰钛交联粘土对染料废水的脱色性能较原土、钠改性蒙脱土、钛交联粘土有显著提高。在室温条件下,当吸附剂用量为2.0g/L,脱色时间为40min,溶液pH值在4～8之间时,甲基橙的脱色率达95%以上。     

纳米级铈锆氧化物固溶体在催化剂中的应用

对以铈锆氧化物固溶体Ce0.75Zr0.25O2为助剂的催化剂进行了活性评价.实验结果表明:固-固化学反应法制备的Ce0.75Zr0.25O2固溶体与传统的共沉淀法制备的Ce0.75Zr0.25O2固溶体在三效催化剂中作为催化助剂的作用是相当的,对模拟汽车尾气起到了很好的净化作用.还研究了Ce0.75Zr0.25O2对交联粘土(PILC)催化剂Cu/CeTi-PILC的丙烯选择性催化还原一氧化氮反应的影响.实验证明:Ce0.75Zr0.25O2固溶体能提高催化剂5%Cu/CeTi-PILC对C3H6和一氧化氮的催化活性,起燃温度明显降低,其中C3H6起燃温度降低了15℃;一氧化氮起燃温度降低了112℃.     

锆铝复合层柱黏土固体超强酸的制备及催化性能

研究了用金属离子掺杂及硫酸根改性提高层柱黏土酸性的方法.由取代法制得锆铝复合交联剂,经离子交换制得锆铝复合交联黏土,再经SO42-改性制得锆铝复合层柱黏土固体超强酸催化剂.利用X射线衍射、红外光谱、氨吸附程序升温脱附、比表面积及孔径分布分析等对催化剂结构进行了表征.实验确定了锆铝复合交联黏土SO42-改性最佳工艺条件.以乙酸正丁酯合成反应为探针对催化剂的活性进行了测试.结果表明:锆铝复合交联剂被成功引入蒙脱石的层间.经SO42-改性后的锆铝复合层柱黏土,其固体酸性得到了强化,是一种比表面积较大且孔径分布较为均匀的固体超强酸催化材料.在硫酸铵溶液浓度为200 g/L,焙烧温度为400～500 ℃的SO42-改性的条件下,乙酸的转化率达93.4%,反应中无副产物产生,催化剂具有良好的重复使用性能.     

椰油酰胺丙基甜菜碱改性粘土/丁腈橡胶纳米复合材料的结构与性能

采用椰油酰胺丙基甜菜碱（CAB）对粘土进行改性,制备改性粘土/丁腈橡胶（NBR）纳米复合材料,并对其结构与性能进行研究。结果表明：改性后的粘土层间距增大,NBR与改性粘土形成了有序插层型纳米复合材料,不同种类的有机粘土在橡胶基体中均达到纳米分散;随着CAB用量的增大,改性粘土在橡胶基体中的分散变好,填料网络结构增强,复合材料的硬度、拉伸强度、拉断伸长率、撕裂强度增大,定伸应力变化不大;与有机粘土I.30P和I.44P相比,当粘土阳离子交换容量与CAB的摩尔比为1∶5时,改性粘土对NBR的补强效果最佳。     

流化催化裂化汽油吸附脱硫金属氧化物吸附剂

制备了不同的金属氧化物吸附剂并采用不同方法进行改性,在常压、温度为360℃、液时空速为1 h-1的条件下,采用固定床吸附法考察了吸附剂改性前后的脱硫性能.结果表明:MoO3和MnO2的脱硫效果较好,对硫含量为511.10 μg/g的流化催化裂化(FCC)汽油脱硫,脱硫率达60%以上;CuO-MoO3,MoO3-MgO和MoO3-Fe2O3复合金属氧化物吸附剂对FCC汽油的脱硫效果可达75%以上,其中脱除乙硫醇效果最好的是CuO-MoO3,脱除噻吩效果最好的是MoO3-MgO,脱除二苯并噻吩效果最好的是MoO3-Fe2O3;采用等体积浸渍法对MoO3和MnO2改性后,对FCC汽油吸附脱硫效果有所增强,其中对MoO3改性效果较好的是NiO,脱硫率可达90.1%,对MnO2改性效果较好的是CoO,脱硫率可达93.2%.     

Cerium Containing Al- and Zr-Pillared Clays: Promoting Effect of Cerium (III) Ions on Structural and Catalytic Properties

Ce³⁺ containing Al- and Zr-pillared clays were prepared by co-hydrolysis and co-intercalation methods, respectively. The materials were characterized by XRD, IR and near IR techniques. The expansion in the clay lattice as a result of pillaring was confirmed from X-ray diffraction study. The basal spacing for the pillared clay materials was observed typically in the range of 18–23 Å. The IR and near IR studies were employed to show the presence of acidic and non-acidic hydroxyl groups in the pillared clays. The IR peak at 3630 cm⁻¹ corresponding to the structural hydroxyl groups was more intense in pillared clays than in the parent clay. This peak is retained even after calcination at 500^∘C. Various overtone and combination bands were observed in the NIR range of 1200–2500 nm for the pillared clay materials. Pillaring with Al- and Zr-inorganic polycations enhanced the catalytic activity of the parent clays for dehydration of cyclohexanol. The presence of Ce³⁺ ions in the pillared clays was found to influence catalytic activity and stability of the Brønsted acidic sites. The stabilizing effect of cerium ion in the pillared clays is attributed to the competitive site occupancy and prevention of octahedral migration of the catalytically active protons.     

Synthesis of pillared clays with Al13-Fe and Al13-Fe-Ce polymers in solid state assisted by microwave and ultrasound: Characterization and catalytic activity

A new methodology for the synthesis of pillared clays with the Al₁₃-Fe and Al₁₃-Fe-Ce polymers in solid state was developed by using microwaves and ultrasound in the aging of the olygomeric solution, in the precipitation of the corresponding sulphates, and in the intercalation of the polymer with the powdered clay. This methodology reduces significantly the water consumption in the intercalation process, and the time for the synthesis of both the polymer in the solid state, and the pillared clay. The resulting polymers were characterized by XRF, XPS, XRD and SEM. The XRF analysis showed that a high percentage of Fe and Ce associated to Al₁₃-Fe and Al₁₃-Fe-Ce sulphates, was dissociated during the exchange process with nitrate. Using XPS analyses we established the presence of Ce (III) in the polymers. By means of XRD and SEM we determined that Al₁₃ and Al₁₃-Fe sulphates present a monoclinical structure, whereas the Al₁₃-Fe-Ce sulphates present two crystalline phases, monoclinical and cubical, whose cell parameters are slightly different from those of the sulphates reported in literature. The XRD, XRF and sortometry analyses showed that the pillared clays (synthesized with the proposed methodology), show more intense and remarkably homogenous pillaring signals, and also better textural properties than the clays pillared by the conventional method of synthesis. The catalytic activity was assessed in the phenol oxidation in dilute aqueous medium at 25 °C and at atmospheric pressure. The solids synthesized showed similar catalytic properties than those reported for the solids synthesized by the conventional method.     

Generation and characterization of catalytic nanocomposite materials of highly isolated iron nanoparticles dispersed in clays

Nanostructured metallic iron particles in montmorillonite matrix have been prepared at ambient temperature through iron intercalation followed by reduction of resulting iron pillared montmorillonite with potassium borohydride. The resulting nanocomposites have been characterized by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDX), transmission electron microscopy (TEM), UV–VIS-diffuse reflectance spectrometer (UV–VIS). The catalytic performances of resulting nanocomposites have been evaluated by probe phenol oxidation reaction with hydrogen peroxide. The results reveal that the nanosized iron polyoxocations intercalated clays can be successfully obtained by conventional synthesis of pillared clays, and after reduction of pillars, the highly dispersed zero-valent iron nanoparticles in clay matrix with diameter in the range of 3–10 nm can be successfully yielded. Over the nanocomposites catalyst prepared at a molar ratio of [CO ₃ ²⁻ ]/[Fe³⁺] = 0.5, the catalytic conversion of phenol oxidation is 49.5% with a 67.4% of selectivity to carbon dioxide and tar. The iron species dispersed in clay matrix may provide the catalytic active sites and the size of iron species has an effect on selectivity. More highly isolated iron nanoparticles dispersed in clays could lead to higher catalytic deep oxidation.     

Effect of Ultrasound on the Structural and Textural Properties of Al–Fe Pillared Clays in a Concentrated Medium

A modification of bentonite with the Al–Fe mixed system in a concentrated medium was performed, assisting the intercalation with ultrasound. The solid pillaring agent and clay powder were placed in a dialysis membrane in contact with a minimum amount of water, and ultrasound was used to promote species exchange. Al–Fe pillared clays (2, 5 and 10 mol% Fe) were characterized by XRF, CEC, XRD, H₂-TPR and N₂ adsorption at 77 K, revealing changes in the structural and textural properties of the modified clays in the presence of ultrasound during the intercalation. The catalytic properties of pillared clays were evaluated by using the catalytic wet peroxide oxidation of phenol in a diluted aqueous medium, showing an activity comparable to that of a solid modified through the conventional method.     

Isomerization of 1-butene catalyzed by ion-exchanged,pillared and ion-exchanged/pillared clays

A natural smectite clay (STx-1, USA) was ion-exchanged with Al, Fe or pillared with polyoxocations of the same metals. Samples were also prepared by combining these two treatments. The prepared solids were characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD), thermogravimetric analysis (TGA), TPD of ammonia and N₂ adsorption. The catalytic activity was evaluated by using the isomerization of 1-butene at 300 °C. XRF results showed an increase in the content of Al or Fe thus giving evidence that these metals were effectively exchanged or deposited over the starting material. Al- and Fe-pillared clays showed a significant increase of the surface area. Ion-exchanged clays showed similar surface areas to that of the starting clay. From XRD patterns only the Al-pillared clay gave an increase of the d-spacing. The synthesized pillared clays were superior catalysts for the isomerization of 1-butene than the ion-exchanged clays; the ion-exchanged/pillared clays showed a similar catalytic behavior as that of the parent pillared clays. The Al-pillared clay was the best catalyst for the reaction and its efficiency was related to the high acidity and high surface area.     

Dehydrogenation of Ethylbenzene on Alumina–Chromia-Pillared Saponites

A natural saponite was intercalated and pillared with hydroxy-aluminium–chromium oligomers. The intercalation solutions were characterized by visible spectroscopy and the pillared saponites mainly by chemical analyses, X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS) and nitrogen adsorption. The catalytic behaviour of these materials in the dehydrogenation of ethylbenzene was investigated. The selectivity to styrene was found to increase as the chromium content of the pillared clays decreased.     

Physicochemical and catalytic properties of Zr-pillared montmorillonite with varying pillar density

Preparation, characterization and catalytic activity of Zr-pillared clays with different pillar density, starting from Ni²⁺ exchanged clay, are described. The physicochemical characteristics of the pillared clays have been evaluated using X-ray diffraction (XRD), thermogravimetric analysis (TGA), infrared (IR), UV–visible diffuse reflectance spectroscopy (UV–VIS-DRS) and sorptometric studies. The decrease in the cation exchange capacity (CEC) of the Ni²⁺ exchanged clay depends upon the pretreatment temperature. The migration of the Ni²⁺ ions into vacant octahedral sites was observed in IR spectroscopy. The acidity of the pillared clays was calculated from TG analysis of the adsorbed n-butyl amine. Alkylation of phenol with methanol was carried out over these catalysts. Good correlation was observed between the alkylation activity and acidity of the pillared materials. Both O and C-alkylation was observed during the reaction. The pillared materials with lesser pillar density were found to be more selective towards anisole which can be attributed to the control in acidic properties of the materials.     

无机层柱粘土材料的制备和应用研究新进展

概述了近年来无机层柱粘土材料新的制备方法,如微波法和超声波法,及其相应的结构表征手段和结构特点,并就基于无机层柱粘土的表面酸性、柱撑体的催化氧化性以及材料多孔性、吸附性等的新应用进行了评述.     

Recent Advances in the Synthesis and Catalytic Applications of Pillared Clays

New methods have been developed in recent years that are now being successfully applied in the preparation of pillared interlayered clays (PILCs). Variations in the procedures concern different parameters involved in the synthesis, such as the starting clay, the intercalating solution, the intercalation process, and the drying and calcination steps of the pillared solids, among others. In the present article, the latest results obtained when introducing modifications in the chemical aspects of PILC synthesis are reviewed. These include (1) pillaring with mixed solutions containing two or more cations, (2) using coordination or organometallic compounds, (3) using polymers and surfactants, (4) pillaring of acid-activated clays, and (5) enhancement of PILC acidity. A separate section is devoted to the specific features of preparing these solids in amounts large enough to make their manufacture on an industrial scale economically feasible. Recent developments in the catalytic applications of PILCs are also reviewed, with emphasis on the progressively more extended use of these materials as catalytic supports.     

Evaluation of the Microporosity of Aluminium Pillared Montmorillonite: Optimisation of the Exchange Process

Aluminium pillared clays were synthesised under various experimental conditions starting from a sodium montmorillonite clay (Hithix). The influence of sonication, successive exchange and a constant pH during and after the intercalation process were investigated as important synthesis parameters in the optimisation of these materials. The concentration of aluminium in the pillaring solution, the ratio of Al/clay and the aging time and temperature were kept constant throughout this work. This optimisation is necessary in order to obtain high-quality Al-PILCs, as could be deduced from a theoretical study on the potential and limitations of pillared clay substrates. The ultrasonic treatment of the suspension during the synthesis is responsible for a significant increase in porosity. Despite the promising nature of the successive exchange technique, a reduction of the porosity is observed. Instead of a homogenisation process, an accumulation of aluminium in the interlayer space occurred. This expected homogenisation takes place when the synthesis of the pillared clay was carried out at constant pH. In this case, nitrogen BET surface areas of 458 m²/g and micropore volumes of 0.17 cm³/g were obtained after calcination of the intercalated clays at 400°C.