柠檬酸溶胶凝胶法合成CeO_2/ZnO/Al_2O_3纳米紫外屏蔽材料

以六水合硝酸铈、六水合硝酸锌以及九水合硝酸铝为原料,采用柠檬酸溶胶凝胶法制备了纳米CeO_2/ZnO/Al_2O_3紫外屏蔽材料。采用X射线衍射(XRD)、扫描电镜(SEM)、傅里叶红外光谱仪(FTIR)和紫外可见分光光度计(UV-Vis)等测试手段对样品进行了表征。结果表明,样品为30～50 nm纳米团状颗粒,并在UVA紫外区域比与同等条件下合成的CeO_2/ZnO更好的吸收。CeO_2/ZnO/Al_2O_3样品在紫外光照射下90 min RhB溶液脱色率仅为23%,具有优良的紫外屏蔽性能,且与CeO_2/ZnO相比没有光催化性。     

CeO_2-CuO/ZnO/Al_2O_3催化合成二乙基甲苯二胺及性质

采用柠檬酸为络合剂,溶胶-凝胶法制备系列CeO_2-CuO/ZnO/Al_2O_3,在3.0 MPa压力和220~230℃反应条件下,甲苯二胺(TDA)和乙烯催化合成二乙基甲苯二胺(DETDA)为探针反应,考察其催化性能,其中CeO_2掺杂量为3%,催化活性最高。通过X射线衍射(XRD)、傅里叶红外光谱(FT-IR)、差热重量分析法(DTG-DTA)、核磁氢谱1 H NMR对CeO_2-CuO/ZnO/Al_2O_3、DETDA、TDA进行检测和表征,揭示了它们的微观结构和内在规律性。XRD检测发现CeO_2掺杂量增多,CeO_2-CuO/ZnO/Al_2O_3衍射峰强度增强,提高了晶化程度,金属原子存在协同效应,增多了活性中心。FT-IR揭示了DETDA内部化学键键型,拥有甲基、亚甲基的多取代芳胺。DTG-DTA检测出的质量变化与热效应两种信息,DETDA的DTG-DTA曲线在66.0、271.0℃存在二个吸热峰,分别为氨基脱离苯环、DETDA的分解产生。通过1 H NMR对DETDA、TDA检测,得到DETDA、TDA的氢原子的数目分别为18和10,分子中各个氢核对应所归属的吸收峰,分别和它们分子式中的氢原子数目吻合。CeO_2-CuO/ZnO/Al_2O_3催化合成DETDA,反应条件温和,工艺流程简单,容易实现高效率和连续化工业生产,因此具有广阔的发展前景。     

CeO_2-CuO/ZnO/Al_2O_3用于1,5-戊二醇气相催化脱氢制备δ-环戊内酯的研究

采用溶胶-凝胶法制备了CeO_2-CuO/ZnO/Al_2O_3,通过XRD检测了CeO_2-CuO/ZnO/Al_2O_3,揭示了CeO_2-CuO/ZnO/Al_2O_3微观结构和内在规律。结果发现,金属离子之间存在协同效应,以1,5-戊二醇气相催化脱氢制备δ-环戊内酯为探针反应,评价其催化活性,3%CeO_2的CuO/ZnO/Al_2O_3呈现出最高催化活性。催化反应的最佳反应条件:反应温度为563 K,气时空速为5 h-1,反应时间为5 h,V(氢气)∶V(1,5-戊二醇)=2.0∶1,p(H2)=0.12 MPa,此时,1,5-戊二醇的转化率为93.0%,δ-环戊内酯的选择性和收率最大值分别达到94.0%、87.4%。该方法为1,5-戊二醇气相催化脱氢制备δ-环戊内酯的中试和工业放大性研究提供了基础数据和实验依据。     

Hydrogen production from steam reforming of methanol over CuO/ZnO/Al2O3 catalysts: Catalytic performance and kinetic modeling

A series of CuO/ZnO/Al_2O_3, CuO/ZnO/ZrO_2/Al_2O_3 and CuO/ZnO/CeO_2/Al_2O_3 catalysts were prepared by coprecipitation and characterized by N_2 adsorption, XRD, TPR, N_2O titration and HRTEM. The catalytic performances of these catalysts for the steam reforming of methanol were evaluated in a laboratory-scale fixed-bed reactor at 0.1 MPa and temperatures between 473 and 543 K. The results showed that the catalytic activity depended greatly on the catalyst reducibility and the specific surface area of Cu. An approximate linear correlation between the catalytic activity and the Cu surface area was found for all catalysts investigated in this study.Compared to CuO/ZnO/Al_2O_3, the ZrO_2-doped CuO/ZnO/Al_2O_3 exhibited higher activity and selectivity to CO,while the CeO_2-doped catalyst displayed lower activity and selectivity. Finally, an intrinsic kinetic study was carried out over a screened CuO/ZnO/CeO_2/Al_2O_3 catalyst in the absence of internal and external mass transfer effects. A good agreement was observed between the model-derived effluent concentrations of CO(CO_2) and the experimental data. The activation energies for the reactions of methanol-steam reforming, water-gas shift and methanol decomposition over CuO/ZnO/CeO_2/Al_2O_3 were 93.1, 85.1 and 116.5 k J·mol~(-1), respectively.     

CeO2/γ-Al2O3脱硫剂的制备及脱硫动力学研究

采用浸渍法制备了0.03gCeO_2/g(γ-Al_2O_3)脱硫剂,X-射线衍射(XRD)表明CeO_2在γ-Al_2O_3载体表面的分布状态是亚单层分布。采用热重分析方法研究了0.03gCeO_2-g(γ- Al_2O_3)脱硫反应的本征动力学,随着SO_2浓度和温度的增加,CeO_2转化率也会增加,得到动力学方程为R=1.14×10~(-4)·exp(-1508.39/T)·C_(SO_2)mg/mgs。动力学参数活化能是12540.78 J/mol,对SO_2的反应级数是1级,指前因子是1.14×10~(-4)mg(mg·s)~(-1)。0.03gCeO_2/g(γ- Al_2O_3)脱硫剂是可再生的,硫化时间过长会降低脱硫剂的可再生性。     

介孔Ag/AgCl/CeO2的制备及其photo-CWPO体系的催化性能

以六水合硝酸铈、硝酸银和嵌段共聚物F127为原料,采用微波辅助软模板法、沉积-沉淀法和光还原法制备了有序介孔Ag/AgCl/CeO_2催化剂。通过XRD、SEM、EDS、TEM、N2吸附-脱附和UV-vis DRS对该催化剂的形貌、结构及化学组成进行了表征与测试。建立了光-催化湿式过氧化反应体系(photo-CWPO),考察了Ag/AgCl/CeO_2在可见光照射下对丙烯腈废水的催化湿式过氧化(CWPO)降解性能。结果表明:制备的Ag/AgCl/CeO_2具有有序的介孔结构,Ag和Ag Cl在CeO_2表面形成,最佳Ag负载量为2 mmol时获得样品的比表面积为317.5 m2/g,在可见光区有较强的吸收,禁带宽度2.9 eV。微波辅助快速制备的Ag/AgCl/CeO_2催化剂在photo-CWPO体系比单独CWPO体系具有更高的催化性能。Ag负载量、催化剂及H2O_2投加量、pH可影响化学需氧量(COD)的去除率。当丙烯腈废水COD质量浓度为500 mg/L,催化剂用量为200 mg,H2O_2(质量分数30%)投加量为8 mL,反应60 min时,COD去除率可达90%。     

Cu/ZnO/Al_2O_3催化剂用于醋酸仲丁酯加氢制备仲丁醇联产乙醇

采用固定床反应器,研究共沉淀法制备的Cu/ZnO/Al_2O_3催化剂用于醋酸仲丁酯催化加氢制备仲丁醇联产乙醇的催化性能,并考察反应温度、氢酯物质的量比、反应压力和空速对反应的影响。结果表明,Cu/ZnO/Al_2O_3催化剂表现出优良的催化性能,在反应温度210℃、氢酯物质的量比15、反应压力4.0MPa和空速1.0h-1条件下,醋酸仲丁酯转化率大于99%,仲丁醇选择性大于99%,乙醇选择性大于97%。推测Cu/ZnO/Al_2O_3催化剂上醋酸仲丁酯加氢制备仲丁醇联产乙醇的反应网络,仲丁醇与乙醇的脱氢反应和脱水反应、烯烃饱和加氢反应和酯交换反应是该体系在Cu/ZnO/Al_2O_3催化剂上存在的主要副反应。     

Ni-CeO_2/Al_2O_3催化剂的制备、表征及其生物质合成气甲烷化性能研究

采用共浸渍法制备了添加不同助剂(CeO_2、ZrO_2、Co_3O_4、Y_2O_3、V_2O_5)的一系列Ni基催化剂,采用XRD、SEM、BET、H_2-TPR等对催化剂的结构进行表征,对Ni含量、助剂含量、浸渍顺序、焙烧温度、还原温度、空速等条件进行优化,并考察了催化剂的生物质合成气甲烷化性能。结果表明:助剂CeO_2、ZrO2、Y_2O_3、V_2O_5的加入均能提高催化剂对CO甲烷化的催化活性,其中6Ni-3CeO_2/Al_2O_3的催化活性、稳定性和抗积碳能力最好;采用6Ni-3CeO_2/Al_2O_3催化剂,在V(H_2)∶V(CO)∶V(N_2)=0.45∶0.15∶0.40、空速为20 000h-1、常压、350℃下,CO即可完全转化,甲烷选择性达到90%,较6Ni/Al_2O_3催化剂提高了16%,CO完全转化温度较6Ni/Al_2O_3催化剂低50℃。6Ni-3CeO_2/Al_2O_3催化剂的Ni含量明显低于文献报道,应用于生物质合成气催化加氢转化为甲烷,CO转化率达到80.5%,有效地解决了生物质合成气中CO含量高于民用燃气标准的问题。     

聚苯胺/纳米Al_2O_3复合材料的制备及其防腐性能研究

在纳米Al_2O_3粒子存在的情况下,以苯胺单体为原料,过硫酸铵为氧化剂,采用化学氧化聚合法制备了聚苯胺/纳米Al_2O_3,复合物。分别用扫描电子显微镜(SEM)、X射线衍射仪(XRD)、紫外-可见分光光度计(UV-vis)和傅里叶变换红外光谱(FTIR)对产物进行形貌观察和结构表征。将涂覆含有聚苯胺和聚苯胺/纳米Al_2O_3,复合物涂层的碳钢片,浸泡于质量分数为3.5%的NaCl溶液中,通过开路电位、极化曲线和交流阻抗来评价涂层的防腐性能。结果表明,涂层中含有聚苯胺/纳米Al_2O_3复合物的碳钢片抗腐蚀能力强于含聚苯胺的碳钢片,腐蚀电位最高,腐蚀电流密度最小;而裸钢片腐蚀电位最小,腐蚀电流密度最大。     

对CeO_2/Cu-Co-O/Al_2O_3催化剂的表征分析及其催化燃烧甲苯的性能研究

以γ-Al_2O_3为载体,采用等体积浸渍法制备了CeO_2/Cu-Co-O/Al_2O_3催化剂。采用SEM、XPS、XRD等技术对催化剂的微观结构和理化性质进行了表征。在固定床反应器上,以甲苯为目标污染物进行了CeO_2/Cu-Co-O/Al_2O_3催化剂的催化燃烧性能研究,考察了焙烧温度对其催化活性的影响。结果表明,所制备的催化剂表面的铜主要以Cu⁽²⁺⁾和Cu(2+)和Cu⁺的化学价态存在,钴主要以Co+的化学价态存在,钴主要以Co⁽²⁺⁾和Co(2+)和Co⁽³⁺⁾的化学价态存在,铈主要以Ce(3+)的化学价态存在,铈主要以Ce⁽⁴⁺⁾的化学价态存在。当焙烧温度达到600℃时,甲苯转化率达到最高,催化活性最佳。     

Self-organized nano-crystallisation of BaF2 from Na2O/K2O/BaF2/Al2O3/SiO2 glasses

In glasses with the compositions (100 ? x)(2Na₂O·16K₂O·8Al₂O₃·74SiO₂)xBaF₂ (with x = 0 to 6), the glass transition temperature decreases with increasing BaF₂-concentration. Samples with x = 6 were thermally treated at temperatures in the range from 500 to 600 °C for 5–160 h. This leads to the crystallisation of BaF₂. The quantity of crystalline BaF₂ increases with increasing time of thermal treatment, while the mean crystallite size remains constant within the limits of error. The glass transformation temperature of partially crystallised samples increases with increasing crystallisation time and approaches a value equal to the temperature, at which the samples were treated. This is explained by the formation of a highly viscous layer enriched in SiO₂ which is formed during crystallisation. This layer acts as a diffusion barrier and hinders further crystal growth.     

The System Na2O-CaO-SiO2-H2O

A portion of the quaternary phase diagram for Na₂O-CaO-SiO₂-H₂O has been constructed. Plotting concentrations as their 10th roots allows compounds having solubilities which differ by several orders of magnitude to be represented on a single diagram. The compositional relationships among sodium-substituted calcium silicate hydrate, calcium-substituted sodium silicate hydrate, calcium bydroxide, a quaternary compound of approximate composition 0.25Na₂O · CaO · SiO₂· 3H₂O, sodium hydroxide monohydrate, and miscellaneous sodium silicate hydrates are presented. The quaternary diagram constructed shows the quaternary compound to exist in equilibrium with sodium-substituted calcium silicate hydrate and calcium hydroxide. Conditions in concrete pore solutions which favor the formation of this quaternary compound may also favor the occurrence of the alkali-silica reaction.     

Prediction of Immiscibility Boundaries of the Systems K2O-SiO2, K2O-Li20-SiO2, K20-Na2O-Si02, and K2O-BaO-SiO2

In earlier work, a prediction method of the immiscibility boundary of a ternary silicate glass system was developed involving two known binary immiscibility boundaries and a measured immiscibility temperature of one ternary glass composition. In the present work, the method is extended to the case where one of the two binary immiscibility boundaries is not known and is applied as an example to ternary silicate systems containing K₂O. First, the immiscibility boundary of the system K₂O-SiO₂ is estimated by measuring the immiscibility temperatures of three glasses in the system K₂O-Li₂O (or Na₂O)-SiO₂. Using this result the immiscibility boundaries of the systems K₂O-Li₂O-SiO₂, K₂O-Na₂O-SiO₂, and K₂O-BaO-SiO₂ are estimated. The results agree reasonably well with the experimentally determined immiscibility temperatures at selected compositions.     

复合固体超强酸SO42-/ZrO2-Al2O3催化合成乳酸正丁酯的研究

合成了几种不同Zr、Al原子比的SO42-/ZrO2-Al2O3复合固体超强酸,将其用于催化乳酸与正丁醇的酯化反应,均有较好的催化活性,尤以ZrAl=12的催化效果最好,经济性优于ZrO2超强酸催化剂.其最佳反应条件为酸醇摩尔比为13,催化剂用量为乳酸质量的10%,反应时间2～2.5h,酯化率达96.9%.该催化剂具有制备容易、催化活性高、不污染环境、可重复使用的优点.     

Some Properties of the System Na2O-NaF-B2O2-H2O

It was first shown that the enamel slips which have the best suspnding characteristics contain equal amounts of Na₂O and B₂O₃ and at least a moderate amount of NaF. The solubilities of mixtures of Na₂O, NaF, and B₂O₃ were then investigated. The pH of these solutions and the primary crystalline phases separating on evaporation also were determined. The solubility data obtained at room temperature were summarized. When the solutions were evaporated, NaF was the first crystalline phase to separate from a large proportion of the mixtures investigated. It was concluded that the desirable handling characteristics of enamels whose mill liquors contain the proper proportion of Na₂O, NaF, and B₂O₃ are not due to the formation of complex salts but to the following combination of properties: (1) the presence of salts with a moderate solubility which changes very slightly with temperature, (2) a moderate pH of about 10 in a probably well-buffered solution, (3) a relatively stable crystalline material, NaF, as a primary phase, and (4) a secondary phase which crystallizes slowly with relatively little shrinkage.     

固体超强酸SO^2—4／TiO2催化合成尿囊素的研究

用固体超强酸SO42/TiO2为催化剂,以尿素和乙醛酸为原料合成了尿囊素。得到最佳条件为TiO2在1mo1·L-1H2SO4溶液中浸渍12h,再在600℃焙烧3h;尿素与乙醛酸摩尔比3.51,催化剂9％,时间3h,温度72℃～75℃,产率达57.4％。     

Photocatalytic activity of Cu2O/TiO2, Bi2O3/TiO2 and ZnMn2O4/TiO2 heterojunctions

Cu₂O/TiO₂, Bi₂O₃/TiO₂ and ZnMn₂O₄/TiO₂ heterojunctions were studied for potential applications in water decontamination technology and their capacity to induce an oxidation process under VIS light. UV–vis spectroscopy analysis showed that the junctions-based Cu₂O, Bi₂O₃ and ZnMn₂O₄ are able to absorb a large part of visible light (respectively, up to 650, 460 and 1000 nm). This fact was confirmed in the case of Cu₂O/TiO₂ and Bi₂O₃/TiO₂ by photocatalytic experiments performed under visible light. A part of the charge recombination that can take place when both semiconductors are excited was observed when a photocatalytic experiment was performed under UV–vis illumination. Orange II, 4-hydroxybenzoic and benzamide were used as pollutants in the experiment. Photoactivity of the junctions was found to be strongly dependent on the substrate. The different phenomena that were observed in each case are discussed.     

Phase Diagrams for the Systems MgCl2-MgF2, CaCl2-MgF2, and NaCl-MgF2

Equilibrium phase diagrams for the systems MgCl₂-MgF₂, CaCl₂-MgF₂ and NaCl-MgF₂ were determined by differential thermal analysis, thermal analysis, and temperature-composition equilibrium techniques. Simple eutectics were observed at 78.0±0.5 mol% MgCl₂ and 628°±2°C in the MgCl₂-MgF₂ system, at 87.5±0.5 mol% CaCl₂ and 694°±2°C in the CaCl₂-MgF₂ system, and at 95.5±0.5 mol% NaCl and 786°±3°C in the NaCl-MgF₂ system. The phase diagrams determined for these systems were compared with phase diagrams that were computed using Temkin's model. The phase diagrams of the CaCl₂-MgF₂ and NaCl-MgF₂ systems were also compared with diagrams that were computed using the expression suggested by Flood et al. for reciprocal systems. The experimentally determined and computed phase diagrams agreed for the MgCl₂-MgF₂ system but not for the CaCl₂-MgF₂ and NaCl-MgF₂ systems.     

Crystallization of zeolite L from Na2O-K2O-Al2O3-SiO2-H2O system

Zeolite L powder was prepared from the substrate mixture of Na₂O-K₂O-Al₂O₃-SiO₂-H₂O system at temperatures of 373-443 K. In order to investigate the factors which influence the synthesis outcome, a reference system which yields zeolite L in a reproducible manner was chosen and subjected to controlled changes in synthesis parameters. The crystalline zeolite L samples obtained were characterized by elemental chemical analysis, X-ray diffraction (XRD), and scanning electron microscopy (SEM). It was established that phase purity, morphology, and the size of crystals of crystalline product were affected by molar ratios of the substrate, such as SiO₂/Al₂O₃, (K₂O+Na₂O)/SiO₂, Na₂O/(K₂O+Na₂O), and H₂O/(K₂O+Na₂O). Amorphous silica powder (Zeosil) was the preferred silica source, and the crystallization rate was promoted by introducing gel aging, seeding, and rapid heating rate.