S2O2-8/ZrO2-Al2O3-SiO2固体超强酸的制备及催化活性研究

采用共沉淀法制备S2O2-8/ZrO2-Al2O3-SiO2固体超强酸催化剂.通过单因素实验考察了三种金属最佳配比、陈化时间、S2O2-8的最佳浓度、浸泡时间、焙烧温度、焙烧时间等对固体酸酸强度的影响.研究表明,固体超强酸S2O2-8/ZrO2-Al2O3-SiO2的最佳制备条件是:n(Zr)∶n(Al)∶n(Si)=1∶2∶1,陈化时间5 h,S2O2-8的浓度为0.75 mol/L,浸渍时间3 h,焙烧温度400 ℃,焙烧时间4 h.此外,还利用红外光谱对样品结构进行了表征,利用酯化反应对其催化活性进行了初步研究.     

SO42-/Fe2O3-Al2O3-TiO2固体超强酸的制备及催化活性研究

采用共沉淀法制备SO42-/FeO3-Al2O3-TiO2固体超强酸.通过正交实验考察了3种金属最佳配比,陈化时间,硫酸浸渍浓度,浸渍时间,焙烧温度,焙烧时间等因素对酸强度的影响.研究表明,SO42-/Fe2O3-Al2O3-TiO2固体超强酸最佳制备条件是:n(Fe):n(AL):n(Ti)=1:2:2,陈化时间3h,浸渍H2SO4浓度1.0mol·L-1,浸渍用量15mL·g-1,浸渍时问20min,焙烧温度500℃,焙烧时间5h.此外,还利用红外光谱对催化剂进行了结构表征,利用酯化反应对其催化活性进行了初步研究.     

S_2O_8~(2-)/ZrO_2-Al_2O_3-TiO_2固体超强酸的制备及催化活性研究

本文采用单因素实验法,研究了固体超强酸催化剂S2O82-/ZrO2-Al2O3-TiO2的制备工艺。结果表明,S2O28-/ZrO2-Al2O3-TiO2的最佳制备条件为:n(Zr)∶n(Al)∶n(Ti)=1∶3∶1,(NH4)2S2O8浸渍液浓度0.5mo.lL-1,浸渍时间2h,焙烧温度300℃,焙烧时间6h。此外,用红外光谱对固体酸进行了结构表征,以乙酸正丁酯的酯化反应对其酸催化活性进行了初步研究。     

S2O2-8/ZrO2-Al2O3-TiO2固体超强酸的制备及催化活性研究

本文采用单因素实验法,研究了固体超强酸催化剂S2O2-8/ZrO2-Al2O3-TiO2的制备工艺.结果表明,S2O2-8/ZrO2-Al2O3-TiO2的最佳制备条件为:n(Zr):n(Al):n(Ti)=1:3:1,(NH4)2S2O8浸渍液浓度0.5mol·L-1,浸渍时间2h,焙烧温度300℃,焙烧时间6h.此外,用红外光谱对固体酸进行了结构表征,以乙酸正丁酯的酯化反应对其酸催化活性进行了初步研究.     

S2O82-/ZrO2-TiO2固体超强酸催化剂的制备及其酯化性能

利用共沉淀和低温陈化法制备S2O82-/ZrO2-TiO2固体超强酸作为合成硬脂酸正丁酯的催化剂.通过XRD、FT-IR和SEM对催化剂进行表征,考察n(Zr)∶n(Ti)、焙烧温度、浸渍液浓度和浸渍时间对催化剂催化活性的影响,以酯化合成硬脂酸正丁酯实验为探针,同时考察反应温度和n(硬脂酸)∶n(正丁醇)对酯化率的影响.结果表明,在n(Zr)∶n(Ti) =2∶2、浸渍液(NH4)2S2O8浓度0.5 mol·L-1、浸渍时间6h、焙烧温度500℃、n(硬脂酸)∶n(正丁醇)＝1∶3、催化剂用量0.2 g、反应温度120℃和反应时间3h条件下,酯化率可达98.69％.     

SO42-/Fe2O3-Al2O3-SiO2固体超强酸的制备及催化活性研究

采用化学共沉淀和单因素法制备新型固体超强酸催化剂SO42/Fe2O3-Al2O3-SiO2,研究得到催化剂的最佳制备条件为:铁、铝、硅物质的量之比1:2:1,陈化时间6h,浸渍硫酸浓度0.75mol/L,浸渍时间40min,焙烧温度500℃,焙烧时间5 h.用红外光谱对固体酸进行了表征,以乙酸正丁酯的酯化反应对其催化活性进行了初步研究.     

稀土Sm促进的S2O82-/SnO2-Fe2O3固体酸的制备及表征

以(NH4) 2S2O8溶液为浸渍溶液,采用溶胶-凝胶法制备了添加稀土Sm元素的固体酸催化剂S2O82-/SnO2-Fe2O3-Sm2O3,采用FT-IR、XRD、TG-DTA等分析方法对催化剂进行表征.将催化剂应用于乙酸正丁酯的合成反应,考察了铁锡元素摩尔比、浸渍液浓度、焙烧温度、焙烧时间和稀土含量等条件对固体酸催化性能的影响,得到催化剂的最佳制备条件为:铁锡元素摩尔比为1∶4,(NH4)2S2O8浸渍液浓度为2.0 mol/L,焙烧温度为500℃,焙烧时间为2.5h,添加稀土氧化钐含量为3％,乙酸正丁酯的酯化率最高达98％以上.添加稀土Sm元素的催化剂稳定性能良好,再生实验表明催化剂结焦及S2O2-基团的流失是催化剂失活的主要原因.     

SO^2-4／ZrO2-La2 O3固体超强酸催化合成邻苯二甲酸二丁酯

采用ZrOCl2·8H2O和La(NO3)3·9H2O共沉淀法制备固体超强酸SO2-4/ZrO2-La2O3催化剂.固体超强酸SO2-4/ZrO2-La2O3制备条件为nZr/nLa为6 ∶ 1,-15 ℃陈化24 h,120 ℃干燥12 h,浸渍液硫酸浓度为0.5 mol/L,浸渍4 h,120 ℃干燥1 h,600 ℃焙烧4 h.将此固体超强酸用于邻苯二甲酸酐和正丁醇合成邻苯二甲酸二丁酯的酯化反应,考察了正丁醇和邻苯二甲酸酐的物质的量比、催化剂用量、反应时间、反应温度对酯化反应的影响.结果表明,醇酐的物质的量比为3.5 ∶ 1,催化剂用量为所用邻苯二甲酸酐的2.7%,反应时间3 h,反应温度160 ℃条件下酯化收率达91.6%.     

填料型La2O3/Al2O3-Al催化剂的制备及其催化性能

以n水硝酸镧[La(NO3)3·n H2O]为原料,阳极氧化铝(Al2O3-Al)为载体,采用水热合成法将活性组分负载在Al2O3-Al上,制备了填料型固体碱催化精馏元件La2O3/Al2O3-Al,以丙酮缩合制备二丙酮醇为探针反应,考察了制备条件对催化剂性能的影响。采用XRD、SEM对催化剂的性能进行了表征。结果表明,活性组分La2O3均匀分散在载体Al2O3-Al表面上。当La(NO3)3·n H2O与氨水(NH3·H2O)的摩尔比为1∶8,油浴温度为160℃,油浴时间10 h,N2保护下焙烧温度为550℃,焙烧时间为2 h时,催化剂的活性最高,此时丙酮转化率为4.1%,二丙酮醇选择性98%。     

固体超强酸S_2O_8~(2-)/TiO_2-SiO_2催化合成柠檬酸三丁酯

研究了用S2O82-浸渍钛硅复合氧化物,制得固体超强酸S2O82-/TiO2 SiO2。用柠檬酸与丁醇的酯化反应来考察制备催化剂的各因素对反应的影响,当反应时间为6h,以及制备催化剂的n(Ti)∶n(Si)为1∶1,(NH4)2S2O8溶液的浓度为0.3mol/L,浸渍时间为8h,焙烧温度为400℃及焙烧时间为5h等情况下制得的催化剂具有很高的催化活性。在合适的条件下,用于催化柠檬酸和正丁醇的酯化反应,可得无色透明的酯化产物柠檬酸三丁酯,酯化率较高,且催化剂可重复使用。     

钕-铝系稀土色料的研制

通过钕-铝系列色料合成实验,分析不同配比及不同矿化剂等对色料呈色效果的影响,确定最佳工艺方法。对实验结果进行XRD及色度分析,确定其主晶相为钕酸铝,试样的明度均在70以上,色彩鲜艳亮丽。     

Polycrystalline In2O3 and In2O3/Y2O3 photoanodes

Single crystal In₂O₃ shows promise as a photoanode for the decomposition of water. Because of various difficulties in the preparation of the single crystal material, two simple techniques were developed for the preparation of polycrystalline In₂O₃ anodes. One method involves the thermal decomposition of the nitrate while the other utilizes the chemical vapour deposition technique. Voltammograms and photoresponse spectra of these anodes are compared to the single crystal material. Among other observations, it is noted that the quantum efficiencies of the thermally decomposed films are comparable to the single crystal material. It is also shown that the on-set potential can be shifted to more negative values by forming the mixed oxide In₂O₃/Y₂O₃.     

Phase equilibrium in binary La2O3-Dy2O3 and ternary CeO2-La2O3-Dy2O3 systems

Cerium oxide doped with oxides of rare earth elements is a multifunctional material, a wide range of uses which is associated with its unique physicochemical properties. Phase diagrams of multicomponent systems are the physicochemical basis for the creation of new materials with improved characteristics.In this work, phase equilibria in ternary CeO₂–La₂O₃–Dy₂O₃ and binary La₂O₃–Dy₂O₃ systems in the whole concentration range were studied. No new phases have been identified in these systems. An isothermal section of the phase diagram of the CeO₂–La₂O₃–Dy₂O₃ system at a temperature of 1500 °С is constructed. No new phases have been detected in the system. It was found that in the studied ternary system solid solutions are formed on the basis of (F) modification of CeO₂ with structure of fluorite type, monoclinic (B), cubic (C) and hexagonal (A) modifications of Ln₂O₃.In the La₂O₃–Dy₂O₃ binary system (1500–1100 °С) three types of solid solutions are formed: based on hexagonal modification A-La₂O₃, monoclinic modification B-Dy₂O₃ and cubic modification C-Dy₂O₃ separated by two-phase fields (A+B) and (B+C), respectively. The boundaries of the regions of homogeneity of solid solutions based on A-La₂O₃ are determined by compositions containing 35–40, 20–25, 15–20 mol% Dy₂O₃ at 1500, 1250, 1100 °C, respectively. From the obtained data it follows that the solubility of Dy₂O₃ in the hexagonal modification of lanthanum oxide is 39 mol% at 1500 °C, 23 mol. % at 1250 °C and 16 mol% at 1100 °C. The limits of existence of solid solutions based on monoclinic B-modification are determined by compositions containing 30–35, 65–60 (1250 °С), 35–40, 55–60 (1100 °С) 40–45, 70–75 (1500 °C) mol% Dy₂O₃.In the studied system, with a decrease in temperature from 1500° to 1100°C, there is a decrease in the solubility of La₂O₃ in the crystal lattice of cubic solid solutions of C-type from 16 to 10 mol%.     

Na2O-Al2O3-Fe2O3系烧结过程中铝、铁的反应行为

以Al2O3, Fe2O3和Na2CO3为原料,对Na2O-Al2O3-Fe2O3系烧结过程中的反应行为进行了详细研究. 基于溶出率与时间、温度的关系,证明Na2O×Al2O3和Na2O×Fe2O3的生成反应动力学都服从Zhuralev-Lesokin-Tempelman模型,表观活化能分别为186.59和80.92 kJ/mol,表明Na2O×Fe2O3比Na2O×Al2O3在动力学上更易形成;Al2O3易与Na2O×Fe2O3反应形成Na2O×Al2O3和Fe2O3,在1273 K烧结30 min,所得熟料Al2O3溶出率达98.51%;Fe2O3对Na2O×Al2O3的形成有双重作用,在1273 K下可加速Na2O×Al2O3的形成,超过1323 K,促使Na2O×Al2O3分解成Na2O和b-Al2O3,且随着温度升高或时间延长,分解程度增高,从而导致熟料中Al2O3溶出率显著降低.     

Fe2O3-MnO-Cr2O3-La2O3系统紫色颜料的制备及表征

采用溶胶均匀共沉淀法于低温下合成了含少量稀土氧化物La2O3的紫色颜料，并采用颜色测定、SEM、XRD等手段对颜料的颜色、检度及结晶构造等进行了表征。     

Separation of Phases by Spinodal Decomposition in the Systems Al2O3−Cr2O3 and Al2O3−Cr2O3−Fe2O3

Separation of phases was investigated in the hexagonal (rhombohedral) systems Al₂O₃−Cr₂O₃ and Al₂O₃−Cr₂O₃−Fe₂O₃. The binary system shows a miscibility gap with a T_c of 950°C; the miscibility gap for the ternary system was determined for a constant Cr₂O₃ content of 16.6 mol%. Dark field transmission electron microscopy of solid solutions annealed within the miscibility gap showed dark and light lamellas ∼50 to 200 Å thick. X-ray diffraction results for the solid solutions in the ternary system indicated that, in the early stages of annealing, broadening occurred only on (hkl) reflections where l≠0. There was no major change in the X-ray diffraction patterns of the annealed solid solutions in the binary system. Electron diffraction results indicated, however, that phase separation in both systems proceeded in the [001] direction. Solid solutions in the binary system separated very slowly; the separation could be enhanced hydrothermally. The mechanism of the separation of phases in both systems is spinodal and proceeds as follows: solid solution→intermediate modulated phase→equilibrium phases.     

ß-Al2O3 synthesis from m-Al2O3

-Al₂O₃ formation fromm-Al₂O₃ was found by a new convenient technique. By thermal decomposition of a complex compound, trioxalatoaluminate Na _x (NH₄)_3–x [Al(C₂O₄)₃]yH₂O(0.091 x 0.333;y= 3), a very fine powder ofm-Al₂O₃ was formed. The decomposition process was examined by thermal analysis and X-ray diffraction and the phase relation of the system Na₂O-Al₂O₃ in the midtemperature region between 600 and 1200° C is discussed briefly. The tablet ofm-Al₂O₃ was fired at 1600° C for 30 min to prepare dense-Al₂O₃ ceramics, the apparent density of which was greater than 95% of the theoretical value. The sintered tablet was examined from the structural point of view and the electrical conductivity was measured by an a.c. method to verify that the procedure of the complex decomposition is a suitable technique for-Al₂O₃ synthesis.     

Bactericidal Effectiveness of O3, O3/H2O2 and O3/TiO2 on Clostridium perfringens

The purpose of this research is to evaluate the bactericidal capacity of different Advanced Oxidation Treatments (AOTs) based on ozone: ozone, ozone/hydrogen peroxide and ozone/titanium dioxide on a wild strain of Clostridium perfringens, a fecal bacterial indicator in drinking water. The dose of ozone consumed ranges from 0.6 mg L^?1 min^?1 to 5.13 mg L^?1 min^?1 depending on the process and on the sample. In the treatments combined with O₃, H₂O₂ dose utilized is 0.04 mM and TiO₂ dose, 1 g L^?1. In order to evaluate the influence of natural organic matter and suspension solids over the disinfection rate, treatments are performed with two types of water – natural water from Ebro River (Zaragoza, Spain) and NaCl solution 0.9%. To achieve 4 log units of inactivation, 3.6 mg O₃ L^?1 is necessary in O₃ treatment, 4.25 mg O₃ L^?1 in O₃/TiO₂ system and 2.7 mg O₃ L^?1 in O₃/H₂O₂ after processing the natural water. In NaCl solution, to get the same inactivation, 0.42 mg O₃ L^?1 is necessary in O₃ treatment, 1.15 mg O₃ L^?1 in O₃/TiO₂ system and 0.06 mg O₃ L^?1 in O₃/H₂O₂ process. Even though the three treatments studied have a high bactericidal activity due to the number of surviving bacteria decreases to non-detectable levels, O₃/H₂O₂ is the most effective system for eliminating C. perfringens cells in a lower contact time, followed by O₃ and finally O₃/TiO₂ system.     

Oxide/oxide composites in the system Cr2O3-Y2O3-Al2O3

Ceramic compacts in the systems Al₂O₃–Y₂O₃, Cr₂O₃–Y₂O₃ and Y₃(Cr_yAl_1-y)₅O₁₂ (Cr-doped YAG) were prepared by solid state reaction in calcined co-precipitated powder mixtures of appropriate compositions. Various solid-solution phases were formed, e.g. Y₃(Al_1-xCr_x)₅O₁₂, YAl_yCr_1-yO₃ and Al_2-xCr_xO₃. Composite materials in the pseudo-binary or ternary systems Al₂O₃–Y₃Al₅O₁₂, Cr₂O₃–Y₂O₃ and Y₃(Al_1–xCr_x)₅O₁₂–YAl_yCr_1–yO₃–(Al_zCr_1−z)₂O₃ were obtained by hot-pressing appropriate powder precursors at 1600–1650°C for 1 h. The microstructure of the prepared materials was studied in a scanning electron microscope with element analysis facilities. X-ray diffraction was used to reveal the phases present and their lattice parameters. The chemical compatibility of these phases was investigated. The results are discussed with a special emphasis on the solubility of Cr in the YAG structure, and on the compatibility relationship between Cr-doped YAG and its neighbouring phases. A gel-coating process for preparing Al₂O₃–YAG composites with tailored microstructures is also described.