Mo/MCM-41-Type mesoporous materials doubly promoted with Fe and Ni for hydrotreating reactions

A Si-MCM-41-type material was synthesized and impregnated with a Mo solution in order to get a 15% MoO₃ by weight. Then, it was doubly promoted with Ni and Fe in different proportions. Information on the structure of the precursors was revealed by XRD, TPR and surface area techniques. XRD results showed that the mesoporous materials were not affected for the successive impregnations carried out; while, their specific surface areas was partially blocked. These solids were tested for vanadyl octaethyl porphyrin hydrodeporphirinization (HDP), and individual and competitive reactions of dibenzothiophene (DBT) hydrodesulfurization (HDS) and 2-methyl naphthalene (2MN) hydrogenation (HYD).The DBT HDS activity was higher than 2MN HYD, and the presence of Fe in the catalysts did not produce a synergetic effect for this reactions. However, HDP activities of doubly promoted catalysts were superior to the monopromoted ones.     

Preparation of fine,uniform nitrogen- and sulfur-modified TiO2 nanoparticles from titania nanotubes

TiO₂ nanoparticles modified with nitrogen and sulfur were prepared from titania nanotubes by a facile wet chemistry method. The samples synthesized with different thiourea/TiO₂ ratios showed a uniform nanoparticle size distribution centred at approximately 10 nm with a developed specific surface area of 246 m² g^-1. These modified nanosized photocatalysts exhibited higher photocatalytic activity for the degradation of gaseous isopropanol than unmodified titania nanotubes under visible illumination. This could be attributed to the synergistic effects of a large specific surface area, strong absorption in the visible region, a redshift in the adsorption edge, and surface adsorption modification induced by nitrogen and sulfur compounds.     

Gas sensor based on ordered mesoporous In2O3

We present the preparation of a semiconductor gas sensor based on ordered mesoporous In₂O₃. The In₂O₃ was synthesized by structure replication procedure from cubic KIT-6 silica. A detailed analysis of the morphology of the mesoporous powders as well as of the prepared sensing layer will be shown. Unique properties arise from the synthesis method of structure replication such as well defined porosity in the mesoporous regime and nanocrystallites with high thermal stability up to 450 °C. These properties are useful for the application in semiconducting gas sensors. Test measurements show sensitivity to methane gas in concentrations relevant for explosion prevention.     

TiO2膜/硅胶复合微球的制备及光催化性能

采用硅胶微球为载体,以TiO2溶胶为涂膜液,制备TiO2膜/硅胶复合微球,用XRD,FT-IR和显微镜等对催化剂的物相、形貌行了表征,并考察其对甲基橙溶液的光催化降解性能.结果表明:TiO2膜和硅胶微球之间存在化学键合作用,涂膜5层微球粒径为0.5～3mm,呈白色,水溶液中透明,是理想的光催化材料.其光催化性能随涂膜层数和催化剂用量的增加而增大,涂膜的5层微球甲基橙降解率可达85%.     

TiO2纳滤膜的制备及其离子截留性能

以钛酸四异丙酯为前驱体,通过聚合溶胶路线制备出平均尺寸约1.2 nm的TiO2溶胶.采用浸浆法,经过一次涂膜,在平均孔径约为3nm的片状γ-Al2O3/α-Al2O3支撑体上制备出完整无缺陷的TiO2纳滤膜.详细考察了煅烧温度对非担载膜(TiO2粉末)和TiO2纳滤膜性能的影响.在350℃的煅烧温度下制备出孔径约为1.5nm的TiO2纳滤膜,该膜对PEG的截留分子量为890,纯水渗透通量为5.3 L/(m2 h)(8×105Pa,20℃);并详细考察了该膜对NaCl、CaCl2、Na2SO4、MgCl2和Ni(NO3)25种溶液的截留性能.结果表明,在pH=4,压力5×105Pa的条件下,Ti-350膜对0.025 mol/L CaCl2和MgCl2溶液的离子截留率分别达到96.5%和92.8%.     

Effects of sol aging on mesoporous silica thin films organization

Cetyltrimethylammonium bromide (CTAB) templated mesoporous silica thin films were deposited on glass slides by evaporation-induced self-assembly (EISA) process using a dip-coating method. The effects of sol aging on the mesophase structure of the thin films organization were investigated. Identification of the structures was accomplished by coupling X-ray diffraction (XRD) and transmission electron microscope (TEM) investigations, and corresponding sol was characterized by ²⁹Si solution state nuclear magnetic resonance (²⁹Si NMR) and UV-Vis spectrophotometer for studying the mesophase structure evolution. Results indicate that sol aging has great effects on the mesophase structure of the films organization, which includes degree of order and phase transformation of mesoporous silica thin films. To obtain a better understanding of the effects of sol aging on the mesophase structure, the theories of apparent mass fractal dimension and charge density matching were introduced to explain the self-assembly process.     

低温等离子体技术应用于二氧化钛光催化剂制备与改性

概述了近年来低温等离子体技术制备、改性二氧化钛技术,涉及磁控溅射技术、等离子体增强化学气相沉积、等离子体金属掺杂及非金属掺杂改性等方面的国内外研究进展,并在此基础上对今后低温等离子体技术应用于二氧化钛的发展进行了展望。     

氮镧共掺杂TiO2纳米粉的溶剂热法制备及其可见光催化性能

以TiCl4为钛源,乙醇为溶剂,采用溶剂热法制备了不同氮、镧掺杂量的TiO2纳米粉;以甲基橙为目标降解物,考察了纳米粉在可见光下的光催化性能;采用XRD、FT-IR、UV-Vis等方法表征其结构及光吸收性能.结果表明:溶剂热法制备的TiO2以锐钛矿为主相,N、La掺杂可以促进其向金红石相转变,并且在TiO2表面生成Ti-O-N键和Ti-O-La键.氮、镧掺杂TiO2纳米粉表现较好的可见光催化性能,其中掺杂4%N,0.4%La(物质的量比)光催化剂的吸收红移至580 nm,并且在可见光下的催化活性比纯TiO2提高了5.5倍.     

银含量对射频磁控溅射法制备Ag-TiO_2薄膜能隙和相结构的影响

采取射频磁控溅射法在硅和石英衬底上淀积Ag-TiO_2纳米薄膜,利用X射线衍射仪和紫外可见分光计分析薄膜的相结构和光学性能,研究银含量对Ag-TiO_2薄膜相结构和能隙的影响.结果表明:银含量影响Ag-TiO_2薄膜的相结构,薄膜中的银为金属Ag(Ag~0),随着银含量(0~40%,体积分数)的增加,薄膜的能隙先减后增,但是仍然小于纯TiO_2薄膜的能隙,银的添加明显地改善了TiO_2薄膜对可见光的吸收.     

不同晶型纳米二氧化钛的水热合成

水热法合成了不同晶型、形貌和大小的纳米二氧化钛。利用X射线衍射(XRD)和透射电镜(TEM)对所得的样品进行了表征。研究了pH值、水热反应温度和水热反应时间对纳米二氧化钛晶型、形貌和晶粒尺寸的影响。结果表明,前驱体pH值是决定产品晶型、晶粒尺寸和形貌的主要因素。随着水热反应温度的升高,纳米二氧化钛的晶粒尺寸逐渐变大,但pH=3.0时所形成的锐钛矿型纳米二氧化钛的晶粒尺寸却几乎不变;随着水热反应时间的延长,金红石型纳米二氧化钛晶粒的生长速度最快,而锐钛矿型的纳米二氧化钛的晶粒生长速度则最慢。