Pt/TiO2催化剂上顺酐选择加氢制丁酸

 采用溶胶-凝胶法和超临界乙醇干燥技术制备了Pt/TiO2催化剂,利用X射线衍射、透射电子显微镜、低温N2吸附和X射线光电子能谱等测试手段对催化剂进行了表征,考察了Pt含量、催化剂还原温度和助剂K的含量对其催化顺酐选择加氢制丁酸性能的影响. 结果表明,催化剂还原温度为500 ℃时,反应的主产物为丁酸; 添加适量的K助剂可以提高催化剂中Pt的分散度, K组分起到了电子给予体的作用,使催化剂表面的Pt呈富电子状态,有利于催化剂表面上反应物的吸附和产物的脱附,使催化剂的活性得到明显提高.     

用微波技术制备NiW/TiO2-Al2O3加氢脱硫催化剂

 采用微波技术制备了NiW/TiO2-Al2O3加氢脱硫催化剂,并用NH3-TPD,Py-FT-IR,TPR和TPS(程序升温硫化)对催化剂进行了表征; 以噻吩为模型化合物,在中压固定床微反装置上考察了催化剂的加氢脱硫性能. 结果表明,在w(TiO2)=15%的催化剂样品中,微波处理的催化剂的活性比常规催化剂高. 微波处理改变了载体和催化剂表面的酸性质,催化剂样品表面的强酸酸量减少,弱酸和中强酸酸量增加. 微波处理的催化剂的还原性能和硫化性能均好于常规法制备的催化剂. 这可能是微波技术制备的催化剂具有较高加氢脱硫活性的原因.     

高性能黑色纳米二氧化钛材料研究

二氧化钛是最重要的光电半导体材料之一, 纳米二氧化钛作为最重要的光催化剂所面临的巨大挑战是无法吸收可见光而导致太阳能利用效率低下. 拓展二氧化钛的光谱响应范围是提高其太阳能利用效率的关键. 最近发展的可以有效吸收可见光的黑色二氧化钛受到广泛关注, 我们针对黑色纳米二氧化钛材料展开了一系列工作, 发展出多种黑色二氧化钛材料的制备方法, 获得了太阳能高吸收、 高效光催化的材料. 本文综合了我们的部分研究工作, 概述了所制备黑色纳米二氧化钛的物化性质、 制备方法及其应用, 并提出了该材料的研究方向.     

稀土元素(Ce/Nd/Eu/Gd)与N共掺金红石相TiO2的第一性原理研究

基于密度泛函理论的第一性原理平面波超软赝势计算方法,计算分析了纯金红石相TiO2,Ce、Nd、Eu和Gd四种稀土元素单掺杂金红石相TiO2,以及与N共掺金红石相TiO2的晶体结构、电子结构和光学性质.由掺杂前后的结果分析发现,掺杂后晶胞膨胀,晶格发生畸变;费米能级上移进入导带,导带底部引入杂质能级,提高了掺杂体系的电导率和对可见光的响应;光学性质、介电函数和吸收谱掺杂体系峰值比纯TiO2小,反射谱和能量损耗谱出现红移现象.     

Osteoblast and Chrondrocyte Proliferation in the Presence of Alumina And Titania Nanoparticles

Proliferation of osteoblasts (bone-forming cells) and chondrocytes (cartilage-synthesizing cells) exposed to different sizes of alumina as well as titania particles at various concentrations (from 10,000 to 100g/ml of culture media) was investigated in the present in vitro study. Compared to respective conventional (i.e., micron) particle size ceramics, results provided the first evidence of increased osteoblast and chondrocyte proliferation in the presence of nanoparticles. Material characterization studies revealed that the only difference between respective ceramic particles was nano- and conventional-dimensions; specifically, phase, charge, and chemical properties were similar between different size alumina and titania particles, respectively. Thus, the present study provided the first evidence of a less detrimental effect of nano- as compared to conventional-dimension wear debris on cell function; such wear debris may result from friction between articulating components of orthopedic implants composed of novel nanophase ceramic materials. In this manner, results provided additional evidence to the literature that nanophase ceramics may become the next generation of bone prosthetic materials with improved osseointegrative (i.e., ability to bond to juxtaposed bone in situ) properties.     

Syntheses of spherical silica and titania from alkoxides on a laboratory scale

Summary A process to synthesize silica and titania as spherical packing materials has been investigated on the laboratory scale by the sol-gel method. The silica and titania obtained were tested under normal-phase separation conditions for comparison of their retention characteristics silica witha a commercial. The silica was found to be similar in its retention behaviour to the commercial silica. The titania showed basic properties and strongly retained acidic compounds.     

Kinetics of interaction of toluene with a pre-oxidized vanadia/titania catalyst

A kinetic model for the interaction of toluene with a pre-oxidized vanadia/titania catalyst has been developed. The model is based on two types of oxygen sites and includes 5 steps. It describes satisfactorily the transient behavior of toluene and products (benzaldehyde, CO₂) in the temperature range of 523-633 K. This revised version was published online in August 2006 with corrections to the Cover Date.     

Sol-Gel Processed TiO2-Based Nano-Sized Powders for Use in Thick-Film Gas Sensors for Atmospheric Pollutant Monitoring

Sol-gel routes were used to prepare pure and 5 at% and 10 at% Ta- or Nb-dope TiO₂ nano-sized powders. The thermal decomposition behaviour of the precursors was studied using simultaneous thermogravimetric and differential thermal analysis (TG/DTA). X-ray diffraction (XRD) analysis showed that the powders heated to 400°C were crystalline in the anatase TiO₂ structure. The pure TiO₂ powder heated to 850°C showed the rutile structure. The addition of Ta and Nb inhibited the anatase-to-rutile phase transformation up to 950–1050°C. Ta was soluble in the titania lattice up to the concentration of 10 at%, while the solubility of Nb was 5 at%. Thick films were fabricated with these powders by screen printing technology and then fired for 1 h at different temperatures in the 650–1050°C range. Scanning electron microscopy (SEM) observations showed that the anatase-to-rutile phase transformation induces a grain growth of about one order of magnitude for pure TiO₂. The addition of Ta and Nb is effective to keep the TiO₂ grain size at a nanometric level even at 950°C, though grain growth was observed with increasing temperature. The gas-sensitive electrical response of the thick films were tested in laboratory, in environments with CO in dry and wet air. Conductance measurements showed a good gas response only for the nanostructured titania-based films. For field tests, the prototype sensors were placed beside a conventional station for atmospheric pollutant monitoring. The electrical response of the thick films was compared with the results of the analytical instruments. The same trend was observed for both systems, demonstrating the use of gas sensors for this aim.     

Effect Of The Preparation Method On The Dispersion Of Metallic Particles In Rh/Tio2 Systems

In Rh/TiO₂ systems, the dispersion of Rh particles depends on the reduction temperature and on the preparation method. The capacity for H₂ adsorption is larger for those samples reduced at low than at high temperature.