超临界流体干燥法制备TiO2/ Fe2O3 和TiO2/ Fe2O3/ SiO2 复合纳米粒子及光催化性能

以TiCl₄ 、Fe (NO₃ )₃·9H₂O 和Na₂SiO₃19H₂O 为原料, 采用溶胶凝胶法结合超临界流体干燥法(SCFD)制备了纳米级TiO₂/ Fe₂O₃ 和TiO₂/ Fe₂O₃/ SiO₂ 复合光催化剂。以光催化降解苯酚对所得催化剂的催化活性进行了评价。结果表明, 纳米TiO₂/ Fe₂O₃ 复合粒子与单组分TiO₂ 比较, 复合粒子光催化活性高于单组分的TiO₂, 6h 苯酚降解率高达95.9 %。SiO₂ 的加入可以抑制纳米粒子粒径的长大和晶相的转变, 增强TiO₂ 纳米粒子的热稳定性。复合光催化剂中Fe₂O₃ 最佳掺入量为0.06 %, SiO₂ 最佳掺入量为10 %(摩尔分数) 。并用XRD、TEM 和FTIR 等手段进行了表征。TiO₂ 以锐钛矿型形式存在, SiO₂ 以无定性形式存在。比较了不同制备方法制得的TiO₂/ Fe₂O₃ 复合光催化剂, 得出超临界干燥法制备的光催化剂具有粒径小、比表面积大、分散性好、光催化活性高等特点。采用超临界流体干燥可直接得锐钛型纳米复合光催化剂。     

Effect of controlling nano-sized copper by silver in copper-based catalyst on catalytic oxidation of toluene

Catalytic oxidation of VOC (toluene) over a copper based catalyst was carried out to assess its properties and performance. The Brunauer Emmett Teller (BET) method, X-ray diffraction (XRD), temperature programmed reduction (TPR), N2O pulse titration and energy dispersive spectroscopy (EDS) were used to characterize a series of 5 wt% Cu/gamma-Al2O3 catalysts modified with silver. The experimental results revealed that the addition of silver to 5 wt% Cu/gamma-Al2O3 catalyst highly enhanced its catalytic activity. With increasing addition amount of silver, the light-off curve for complete oxidation of toluene shifted to lower temperature. In addition, the increase of the addition amount of silver caused the copper particle size of 5 wt% Cu/gamma-Al2O3 catalyst to gradually increase. Subsequently, it demonstrated that the increase in the copper particle size is closely associated with the increase in catalytic activity.     

Catalytic activity of CuOn-La2O3/gamma-Al2O3 for microwave assisted ClO2 catalytic oxidation of phenol wastewater

In order to develop a catalyst with high activity and stability for microwave assisted ClO2 catalytic oxidation, we prepared CuOn-La2O3/gamma-Al2O3 by impregnation-deposition method, and determined its properties using BET, XRF, XPS and chemical analysis techniques. The test results show that, better thermal ability of gamma-Al2O3 and high loading of Cu in the catalyst can be achieved by adding La2O3. The microwave assisted ClO2 catalytic oxidation process with CuOn-La2O3/gamma-Al2O3 used as catalyst was also investigated, and the results show that the catalyst has an excellent catalytic activity in treating synthetic wastewater containing 100 mg/L phenol, and 91.66% of phenol and 50.35% of total organic carbon (TOC) can be removed under the optimum process conditions. Compared with no catalyst process, CuOn-La2O3/gamma-Al2O3 can effectively degrade contaminants in short reaction time and with low oxidant dosage, extensive pH range. The comparison of phenol removal efficiency in the different process indicates that microwave irradiation and catalyst work together to oxidize phenol effectively. It can therefore be concluded from results and discussion that CuOn-La2O3/gamma-Al2O3 is a suitable catalyst in microwave assisted ClO2 catalytic oxidation process.     

Passivation of pigment-grade TiO(2) particles by nanothick atomic layer deposited SiO(2) films

Pigment-grade TiO(2) particles were passivated using nanothick insulating films fabricated by atomic layer deposition (ALD). Conformal SiO(2) and Al(2)O(3) layers were coated onto anatase and rutile powders in a fluidized bed reactor. SiO(2) films were deposited using tris-dimethylaminosilane (TDMAS) and H(2)O(2) at 500?°C. Trimethylaluminum and water were used as precursors for Al(2)O(3) ALD at 177?°C. The photocatalytic activity of anatase pigment-grade TiO(2) was decreased by 98% after the deposition of 2?nm SiO(2) films. H(2)SO(4) digest tests were performed to exhibit the pinhole-free nature of the coatings and the TiO(2) digest rate was 40 times faster for uncoated TiO(2) than SiO(2) coated over a 24?h period. Mass spectrometry was used to monitor reaction progress and allowed for dosing time optimization. These results demonstrate that the TDMAS-H(2)O(2) chemistry can deposit high quality, fully dense SiO(2) films on high radius of curvature substrates. Particle ALD is a viable passivation method for pigment-grade TiO(2) particles.     

不同载体Mn-Ce催化剂的制备及其脱硝性能

以TiO_2、SiO_2及Al_2O_3为载体,采用分步共混法制备了三种均质整体式Mn-Ce负载型催化剂,探究了不同载体对催化剂脱硝活性、N2选择性及机械强度的影响。结果表明,以TiO_2和SiO_2为载体的催化剂80℃的脱硝率接近90%,而以Al2O3为载体的催化剂仅达46%。催化剂的表征发现这与Mn-Ce/TiO2和Mn-Ce/SiO2催化剂的比表面积和表面酸量较Mn-Ce/Al2O3更大、更多有关。而三种催化剂的N2选择性在80~200℃之间均接近100%,然而Mn-Ce/SiO2催化剂200℃以上N2选择性比其余两种催化剂差。三种催化剂的机械强度为Mn-Ce/TiO2Mn-Ce/SiO2Mn-Ce/Al2O3,其微观形貌显示这与催化剂体相结构的密实状况有关,各催化剂的活性组分氧化物均以无定形态存在。     

TiO2/SiO2薄膜中的相界扩散及晶化行为研究

本文研究了溶胶一凝胶法制备TiO2／SiO2复合薄膜的晶化行为以及复合薄膜与过渡层的相界扩散采用X-ray衍射分析了50TiO2／50SiO2薄膜中TiO2的析晶特征，研究表明，随热处理温度的升高，薄膜的结构由非晶转变为在SiO2玻璃网络中析出的锐钛矿相，再到锐钛矿和金红石二相共存，最后转变为金红石相，并伴随有磷石英和方石英的析出，且其晶粒尺寸也在逐渐增大．AES分析给出了过渡层的气孔率对复合膜中Ti的扩散能力的影响以及复合膜与过渡层之间碳的分布．SEM及EDS进一步揭示了薄膜表面存在亚微米不均匀区域，在此区域中碳的含量较高．在氧气中，提高热处理温度，可以降低碳的含量.     

Effect of CeO2 doping on catalytic activity of Fe2O3/gamma-Al2O(3) catalyst for catalytic wet peroxide oxidation of azo dyes

In order to find a catalyst with high activity and stability for catalytic wet peroxide oxidation (CWPO) process under normal condition, with Fe(2)O(3)/gamma-Al(2)O(3) and Fe(2)O(3)-CeO(2)/gamma-Al(2)O(3) catalysts prepared by impregnation method, the effect of CeO(2) doping on the structure and catalytic activity of Fe(2)O(3)/gamma-Al(2)O(3) for catalytic wet peroxide oxidation of azo dyes at 25 degrees C and atmospheric pressure is evaluated using BET, SEM, XRF, XRD, XPS and chemical analysis techniques, and test results show that, better dispersion and smaller size of Fe(2)O(3) crystal can be achieved by adding CeO(2), and the content of chemisorbed oxygen can also be increased on the surface of catalyst. CWPO experimental results indicate that azo dyes in simulated wastewater can be efficiently mineralized and the catalytic activity of Fe(2)O(3)-CeO(2)/gamma-Al(2)O(3) can be increased by about 10% compared with that of Fe(2)O(3)/gamma-Al(2)O(3) because of the promotion of the structural and redox properties of the ferric oxide by ceria doped. Leaching tests indicate that Fe(2)O(3)/gamma-Al(2)O(3) and Fe(2)O(3)-CeO(2)/gamma-Al(2)O(3) are stable with a negligible amount of irons found in the aqueous solution after reaction for 2h. It can therefore be concluded from results and discussion that in comparison with Fe(2)O(3)/gamma-Al(2)O(3), Fe(2)O(3)-CeO(2)/gamma-Al(2)O(3) is a suitable catalyst, which can effectively degrade contaminants at normal temperature and atmospheric pressure.     

磁性纳米TiO2/SiO2/Fe3O4光催化剂的制备及表征

以纳米Fe3O4磁粉为核心，采用溶胶一凝胶法制备了TiO2／SiO2／Fe3O4复合光催化剂．用XRD、TEM及元素分析对其结构和表面形貌进行了表征．以具有偶氮染料结构的甲基橙水溶液为目标反应物，评价其光催化活性．结果表明，所制TiO2／SiO2／FeaO4样品为双层包覆型结构，SiO2为中间层，最外层是锐钛矿型的TiO2,该复合光催化剂对甲基橙溶液有较高的光催化活性，并具有可利用其磁性回收重用的特点，应用前景广泛。     

Effects of Additive AlCl3 on Crystal Phase, Particle Size and Microstructural Parameters of Nanocrystalline TiO2 Prepared by HF-PCVD

Nanocrystalline TiO2 was prepared by high frequency plasma chemical vapor deposition (HF-PCVD). The effects of additive AlCl3 on crystal phase, particle size and microstructurai parameters of TiO2 nanocrystallites were investigated by X-ray diffraction(XRD) and transmission electron microscopy (TEM). The nanocrystallites obtained experimentally are mixture of anatase and rutile, the uniform diameters of particles are about 30 nm. The phase transformation from anatase to rutile was accelerated by AlCl3, and rutile content is increased from 26.7 wt pct to 53.6 wt pct with increasing of addition of AlCl3 from 0.0 wt pct to 5.0 wt pct. The particle size is reduced and the size distribution becomes very narrow. The crystal lattice constants have the trend to decrease, and celi volumes appear as shrinkable     

Aqueous phase reforming of glycerol over the Pd loaded Ni/Al2O3 catalysts

Bifunctional catalysts containing (0.5-1.5 wt%) palladium and 15 wt% of Nickel supported on gamma-Al2O3 were prepared via an impregnation technique and catalysts were characterzed by XRD BET surface area and SEM, respectively. The aqueous phase reforming of glycerol (APR) was conducted over alumina-supported catalysts at different reaction conditions for catalytic activity. Finally, we concluded that the 1.0 wt% Pd 15 wt% Ni/gamma-Al2O3 catalyst evidences higher conversion, hydrogen selectivity, lower alkane selectivity and CO production. This indicate that Pd loaded Ni/gamma-Al2O3 could be a potential catalyst for the APR of glycerol.     

纳米TiO2薄膜光催化剂的制备及性能研究

以钛酸四丁酯作为前驱体,用溶胶一凝胶法,在玻璃载体上煅烧制备了纳米TiO2薄膜光催化剂,利用扫描电子显微镜（SEM）、X射线衍射（XRD）等表征技术研究了TiO2薄膜的形貌和特性,其光催化性能用4支20W紫外石英杀菌灯照射TiO2薄膜分解亚甲基兰染料溶液表征,结果表明,该催化剂具有锐钛班红石混合晶相和纳米花状结构,纳米TiO2薄膜的光催化能力随着镀膜层数的增加而增加。     

二氧化钛纳米晶的光催化活性研究

以苯酚的光催化降解为模型反应,研究了锐钛矿相和金红石相二氧化钛纳米晶（７￣４０ｎｍ）的光催化活性。与市售的氧化钛相比,两种晶相的纳米氧化钛均有很高的光催化活性,锐钛矿相氧化钛对苯酚的深度矿化有更高的选择性。ＴｉＯ２吸附的水及羟基会降低氧化钛的光催化活性。由于粒径减小使氧化钛的吸收带边界蓝移,粒径小的氧化钛有更高的催化活性,粒径〈１５ｎｍ时,显示出量子尺寸效应。     

Growth of TiO2 with thermal and plasma enhanced atomic layer deposition

We show a comparative study of the TiO2 ALD with TTIP and either O2 or O2-plasma on Si/SiO2 substrates. In particular we compare the surface morphology and crystalline phase by means of Atomic Force Microscopy (AFM), X-ray Photoelectron Spectroscopy (XPS) and X-ray Absorption Spectroscopy (XAS) for different O2-plasma procedures upon changing the time between cycles and the N2-purging pressure. The AFM images show that already these parameters may induce structural changes in the TiO2 films grown by ALD, with the formation of crystallites with average lateral width varying between 15 and 80 nm. By means of XAS we also found that the crystallites have mixed anatase and rutile crystalline phases and that smaller crystallites have a greater rutile component than the larger ones.     

电参数对Ti6Al4V合金微弧氧化陶瓷膜结构特性的影响

采用交流微弧氧化法于Na₂SiO₃-KOH-(NaPO₃)₆。溶液中在Ti6A14V表面形成了氧化物陶瓷膜.研究了微弧氧化电压与频率对陶瓷膜的生长速率、组织形貌和相组成的影响.结果表明:随电压的升高或频率的减小,膜层的生长速率增加,膜层的表面质量变得粗糙.相对致密均匀的膜层主要由TiO₂(锐钛矿相及金红石相)相组成,电压与频率电参数影响膜层的相组成,随电压的升高和频率的减小,膜层中锐钛矿相TiO₂的相对含量减小,金红石相TiO₂的相对含量增加,并成为主晶相.     

Preparation and characterization of magnetically separable photocatalyst (TiO2/SiO2/Fe3O4): effect of carbon coating and calcination temperature

TiO2/SiO2/Fe3O4 composite was synthesized by sol-gel technique for silica and titania coatings on magnetite core to enable recovery after photocatalytic degradation. Carbon coating was also carried out by calcination of TiO2/SiO2/Fe3O4 under nitrogen atmosphere in presence of PVA as a source of carbon to enhance the adsorption of organic compounds on catalyst surface and to get better activity. All prepared samples were characterized using EDX, CN analyzer, XRD, BET and SEM. Degradation of methyl orange dye was used to assess the photocatalytic performance of the prepared samples. Calcination temperature was found to affect rate of reaction because of the formation of rutile phase at high calcination temperature. Carbon coated samples unexpectedly exhibited lower rate of reaction at almost all calcination temperatures.     

双微乳液法制备掺杂Fe~(3+)的纳米TiO_2及其光催化性能

为了研究双微乳液法在制备纳米级光催化剂的应用,以TiCl4和NH3.H2O为原料,采用十六烷基三甲基溴化铵-正丁醇-环己烷-水微乳体系制备Fe3+掺杂纳米TiO2,对粉末的晶体结构进行X射线衍射表征,并以其对p-甲酚的降解考察其光催化活性。结果表明,在较小的掺杂量时,Fe3+掺杂量的提高可以提高TiO2的光催化活性,进一步提高掺杂量将引起光催化活性的降低;掺杂Fe3+可导致纳米TiO2的粒径减小;Fe3+的半径较小以及Fe2O3的熔点较低均有利于TiO2从锐钛矿向金红石的相变;当Fe3+掺杂摩尔分数为0.06%,煅烧温度为550℃时,纳米TiO2的光催化活性最高,此时形成TiO2的锐钛矿和金红石相的混晶;乳液中含水量也会影响晶相的组成和粒径大小,随着含水量增加产物中出现了一定比例的金红石相。     

Steam reforming of glycerol into hydrogen over nano-size Ni-based hydrotalcite-like catalysts

Steam reforming (SR) of glycerol for the production of hydrogen was investigated over the nano-sized Ni-based catalysts. The Ni-based catalysts were prepared by solid phase crystallization and impregnation methods, and characterized by N2 physisorption, CO chemisorption, XRD, SEM, and TEM techniques. The Ni/gamma-Al2O3 catalyst showed higher conversion and H2 selectivity. However, it was slowly deactivated due to the carbon formation on the surface of catalyst and the sintering. It was found that the Ni based hydrotalcite-like catalyst (spc-Ni/MgAl) showed higher catalytic activity to prevent carbon formation than Ni/gamma-Al2O3 catalyst in the SR of glycerol.     

Supported Cu(II) polymer catalysts for aqueous phenol oxidation

Supported Cu(II) polymer catalysts were used for the catalytic oxidation of phenol at 30 degrees C and atmospheric pressure using air and H(2)O(2) as oxidants. Heterogenisation of homogeneous Cu(II) catalysts was achieved by adsorption of Cu(II) salts onto polymeric matrices (poly(4-vinylpyridine), Chitosan). The catalytic active sites were represented by Cu(II) ions and showed to conserve their oxidative activity in heterogeneous catalysis as well as in homogeneous systems. The catalytic deactivation was evaluated by quantifying released Cu(II) ions in solution during oxidation, from where Cu-PVP(25) showed the best leaching levels no more than 5 mg L(-1). Results also indicated that Cu-PVP(25) had a catalytic activity (56% of phenol conversion when initial Cu(II) catalytic content was 200 mg L(Reaction)(-1)) comparable to that of commercial catalysts (59% of phenol conversion). Finally, the balance between activity and copper leaching was better represented by Cu-PVP(25) due to the heterogeneous catalytic activity had 86% performance in the heterogeneous phase, and the rest on the homogeneous phase, while Cu-PVP(2) had 59% and CuO/gamma-Al(2)O(3) 68%.     

Catalytic combustion of ethyl acetate on supported copper oxide catalysts

Total oxidation of ethyl acetate on supported copper oxide catalysts was investigated. The catalysts have been prepared by wet impregnation method and characterized by XRD, TEM and XPS. Among the catalysts with the supports of TiO2, CeO2/TiO2 and CeO2-ZrO2/TiO2, CeO2-ZrO2 solid solutions doped TiO2 supported catalyst gives the highest catalytic activity. Catalyst with the composition of 5 wt.% CuO/10 wt.% CeO2-ZrO2-TiO2 shows the total oxidation of ethyl acetate at about 270 degrees C with the 100% CO2 selectivity. The characterization studies of supported copper oxide catalysts showed that the highly dispersed CuO is one of the active phase which contacts intimately with the support, the action of the interface between the components was not be ignored.     

TiO2/SiO2复合薄膜的晶化特征和结构转变研究

对TiO2／SiO2复合薄膜的晶化特征进行了分析，研究表明，随着TiO2含量的增加，其晶化温度降低，而由锐钛矿相完全转变为金红石相的速度减慢．SiO2的析晶温度也随着TiO2含量的增加而降低，即TiO2具有诱导SiO2析晶的作用．锐钛矿晶粒尺寸的增加幅度随着TiO2含量的降低和热处理温度的升高而增大．其晶粒尺寸的大小与热处理时间的平方根成正比．认为由于TiO2含量的不同，造成薄膜中由锐钛矿相完全转变成金红石相的速度差异主要来自于薄膜中应力的作用．