TiO2纳米纤维的电纺制备与表征

以PVP作为络合剂与Ti（C4H9O）4反应制得前驱体,采用静电纺丝法制得PVP／TiO2纳米复合纤维后在马弗炉中煅烧,并采用SEM、TG—DTA、XRD等对纳米纤维进行了表征。结果表明：适当增加Ti（C4H9O）4浓度、增加静电电压、减小喷射速度和升高煅烧温度,电纺丝纤维直径变细;PVP／TiO2复合纤维煅烧至550℃时得到的为纯TiO2;经400℃、600℃、700％、900％煅烧后分别得到开始出现锐钛矿型的TiO2、以锐钛矿型的TiO2为主、以金红石型的TiO2为主和完全金红石晶型的TiO2纳米纤维。     

纳米TiO2光催化氧化机理及研究进展

本文探讨了TiO2光催化氧化机理及影响催化反应的因素，综述了在降解有机染料、净化空气和杀菌方面的研究进展。     

纳米TiO2光催化氧化机理及应用

介绍了纳米ＴｉＯ２光催化氧化有机物的机理及其研究进展和实际应用,并对目前光催化氧化技术发展中存在的问题及今后的研究方向提出一些看法。     

TiO2纳米纤维光催化降解罗丹明B溶液

采用静电纺丝技术,以硫酸钛为钛源,成功制备出TiO2纳米纤维。利用XRD和SEM等分析手段对纳米纤维进行了表征。以罗丹明B为降解物,考察了焙烧温度对光催化效果的影响。结果表明,TiO2纳米纤维对罗丹明B可达到较高的降解率。     

强化纳米TiO2光催化氧化能力的研究进展

在光催化技术理论的基础上,概述了纳米TiO2光催化剂的发展概况和特点及纳米TiO2光催化剂降解有机物的机理.重点介绍了目前纳米二氧化钛光催化剂的改良和光催化效率提高的新技术,实验室研究和实际应用上存在的主要问题和技术难点,对这些问题提出了建议与解决方法,并对今后高级氧化水处理技术的应用、发展作了展望.     

TiO2纳米纤维的静电纺丝法制备及其应用

二氧化钛(TiO2)是重要的多功能无机半导体材料,TiO2纳米纤维结合了TiO2特性与纳米特征,克服了粉状TiO2某些应用缺点,因此在众多领域具有潜在应用价值.静电纺丝是制备TiO2纳米纤维的重要方法,其工艺方法有共混法、同轴法、共轭法、并列法和模板法等,不同电纺工艺可以得到不同的产物形貌和性质.本文综述了电纺TiO2纳米纤维的工艺方法现状及应用研究进展,展望了其发展方向和应用前景.     

静电纺TiO2-SiO2复合纳米纤维的制备及其光催化性能研究

采用静电纺丝技术制备了PVP-TiO2-SiO2前驱体复合纳米纤维,利用视频显微镜观察了其成纤状态和形貌结构;经600℃煅烧得到TiO2-SiO2复合纳米纤维,利用FT-IR、XRD、SEM和分光光度计对TiO2-SiO2复合纳米纤维的形成、晶型结构、形貌和光催化降解性能进行了表征。结果表明,经600℃煅烧后,PVP-TiO2-SiO2复合纳米纤维中的PVP被有效的去除,制得无定形TiO2-SiO2复合纳米纤维,且纤维呈圆柱形;TiO2-SiO2复合纳米纤维对亚甲基蓝染液具有良好的光催化效果,且光催化效率随TiO2-SiO2复合纳米纤维用量的增加而提高。     

纳米TiO2在废水处理中的光催化活性

介绍了纳米TiO2光催化降解废水中有机污染物的机理,系统评述了纳米TiO2的粒径、晶型、掺杂、负载和废水处理体系中催化剂投加量、pH值、外加氧化剂、无机盐及光强等因素对其催化活性的影响。展望了纳米TiO2在降解工业废水处理中的应用前景,认为：提高纳米TiO2的光催化效率,扩展纳米TiO2的吸收光谱范围和开发纳米TiO2的负载技术是光催化法处理废水应用研究领域今后的主要发展方向。     

Gd~(3+)掺杂TiO_2纳米纤维的制备、表征及其光催化性能

采用静电纺丝技术并结合溶胶-凝胶方法制备TiO2和TiO2/Gd2O3纳米纤维,采用差热-热重分析(TG-DTA)?场发射扫描电镜(FE-SEM)、红外光谱(FTIR)、X射线粉末衍射(XRD)对材料进行表征,通过亚甲基蓝光降解反应研究其催化性能。结果表明,掺杂Gd3+可以强烈抑制TiO2由锐钛矿相向金红石相的转变,抑制晶粒生长,减少晶粒尺寸;Gd3+掺杂TiO的纳米纤维对亚甲基蓝的光催化活性明显提高。     

纳米TiO2光催化氧化SO2影响因素初探

采用溶胶-凝胶法制备的纳米TiO2光催化氧化SO2并考察了影响纳米TiO2光催化氧化SO2反应的影响因素,包括光强、反应温度、反应时间和SO2的初始浓度。结果显示:反应到一定时间后(大概1h),低浓度的SO2的光催化氧化效率都较稳定;对于较高浓度的SO2,其光催化氧化效率随着光辐照强度的增强而呈现出上升的趋势;在0～120℃的反应温度范围内,光催化氧化效率随着温度的升高而升高;SO2的初始浓度小于1090mg/m3时,光催化氧化效率随SO2初始浓度的增加而升高。     

木质素磺酸钠在TiO2/水界面的吸附特性

木质素磺酸钠在固体表面的吸附特性决定了其应用性能,利用红外和紫外分光光度仪,采用剩余质量分数法研究了温度、pH值、无机盐和氢键破坏剂脲对木质素磺酸钠在TiO₂/水界面吸附动力学和等温吸附性能的影响,初步探讨了其在固液界面的吸附作用机理。结果表明,该吸附为单层多点式吸附,随着温度升高和pH值减小,木质素磺酸钠在TiO₂/水界面的吸附速率常数和饱和吸附量均增大,而离子强度的增大和脲的加入却使吸附速率常数减小;木质素磺酸钠在TiO₂/水界面的吸附驱动力为静电、疏水和氢键作用,疏水作用力可显著增加其吸附量。     

Selective oxidation of methanol to dimethoxymethane over acid-modified V2O5/TiO2 catalysts

Selective oxidation of methanol to dimethoxymethane (DMM) was conducted in a fixed-bed reactor over an acid-modified V₂O₅/TiO₂ catalyst. The influence of the acid modification on its structure, redox and acidic properties, and catalytic performance for methanol oxidation were investigated. The results indicated that the content of vanadia in the catalyst exhibits a vital influence on the dispersion of vanadium species, while the acid modification can enhance its surface acidity. Proper amounts of the acid (W() = 15%) and V₂O₅ (W(V₂O₅) = 15%) components loaded in the acid-modified V₂O₅/TiO₂ catalyst are able to build a bi-functional circumstance that is favorable for the formation of DMM with high activity and selectivity. As a result, for the selective oxidation of methanol, the H₂SO₄-modified V₂O₅/TiO₂ catalyst gives a much higher DMM yield at 150 °C than the unmodified one.     

UV/H2O2氧化联合Ca(OH)2吸收同时脱硫脱硝

在小型紫外光-鼓泡床反应器中,对UV/H₂O₂氧化联合Ca(OH)₂吸收同时脱除燃煤烟气中NO与SO₂的主要影响因素[H₂O₂浓度、紫外光辐射强度、Ca(OH)₂浓度、NO浓度、溶液温度、烟气流量以及SO₂浓度]进行了考察。采用烟气分析仪和离子色谱仪分别对尾气中的NO₂和液相阴离子作了检测分析。结果显示:在本文所有实验条件下,SO₂均能实现完全脱除。随着H₂O₂浓度、紫外光辐射强度和Ca(OH)₂浓度的增加,NO的脱除效率均呈现先大幅度增加后轻微变化的趋势。NO脱除效率随烟气流量和NO浓度的增加均有大幅度下降。随着溶液温度和SO₂浓度的增加,NO脱除效率仅有微小的下降。离子色谱分析表明,反应产物主要是SO₄^2-和NO₃^-,同时有少量的NO₂^-产生。尾气中未能检测到有害气体NO₂。     

SO2 and NO removal from flue gas over V2O5/AC at lower temperatures — role of V2O5 on SO2 removal

Supporting V₂O₅ onto an activated coke (AC) has been reported to significantly increase the AC's activity in simultaneous SO₂ and NO removal from flue gas. To understand the role of V₂O₅ on SO₂ removal, V₂O₅/AC is studied through SO₂ removal reaction, surface analysis, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) techniques. It is found that the main role of V₂O₅ in SO₂ removal over V₂O₅/AC is to catalyze SO₂ oxidation through a VOSO₄-like intermediate species, which reacts with O₂ to form SO₃ and V₂O₅. The SO₃ formed transfers from the V sites to AC sites and then reacts with H₂O to form H₂SO₄. At low V₂O₅ loadings, a V atom is able to catalyze as many as 8 SO₂ molecules to SO₃. At high V₂O₅ loadings, however, the number of SO₂ molecules catalyzed by a V atom is much less, due possibly to excessive amounts of V₂O₅ sites in comparison to the pores available for SO₃ and H₂SO₄ storage.     

Cu-Cr2O3催化剂上二氟乙酸甲酯催化加氢合成二氟乙醇

采用共沉淀法制备了Cu-Cr₂O₃催化剂,考察了铜含量对Cu-Cr₂O₃催化剂的二氟乙酸甲酯加氢合成二氟乙醇性能的影响。运用X射线衍射(XRD)、程序升温还原(TPR)、BET和Raman光谱技术对该催化剂进行了表征。结果表明,还原态Cu-Cr₂O₃催化剂物相主要由Cu和Cr₂O₃组成,然而30Cu-Cr₂O₃和50Cu-Cr₂O₃催化剂存在少量CuCr₂O₄和CuCrO₂复合氧化物。随着铜含量的增加,Cu-Cr₂O₃催化剂的二氟乙酸甲酯单程转化率呈现先上升后下降的趋势,而二氟乙醇选择性保持在70%左右; 30Cu-Cr₂O₃催化剂的二氟乙酸甲酯单程转化率达到最大值97%。Cu-Cr₂O₃催化剂的二氟乙酸甲酯加氢反应比速率随着铜含量的增加呈现增大的趋势,反应比速率的提高可能与催化剂中CuCr₂O₄和CuCrO₂物种的存在有关。     

新型CO2低温捕集与N2/O2分离复合系统性能分析

提出了一种CO₂低温捕集液化与N₂/O₂分离的新型复合系统,并且对该系统的性能以及优势进行了分析。这一系统不仅将CO₂低温捕集液化与N₂/O₂的分离结合起来,而且能达到降低能耗与减少投资的目的。采用理论分析和软件模拟相结合的方法,对该系统进行可行性分析。结果显示,这一新型系统不仅能量消耗低于传统醇胺吸收捕集CO₂的系统,该新型复合系统捕集1 t CO₂耗能3.29 GJ·t^-1,而传统MDEA吸收法耗能4.11 GJ·t^-1。而且在该系统中,CO₂分离液化的同时,可以获得副产物N₂与O₂。本研究阐明了一种CO₂低温捕集液化与N₂/O₂分离复合系统的新思想。     

XANES study of polyaniline-V2O5 and sulfonated polyaniline-V2O5 nanocomposites

In this work, two materials for secondary lithium battery cathodes formed by polyaniline-V₂O₅ and sulfonated polyaniline-V₂O₅, which have a higher charge capacity than the V₂O₅ xerogel, were synthesized. X-ray absorption and Fourier transform infrared spectroscopies were employed to analyze the short-range interactions in these materials. Based on these experiments, it was possible to observe significant differences in the symmetry of the VO₅ units, and this was attributed to the intimate contact between V₂O₅ and the polymers, and to some flexibility of the VO₅ square pyramids due to the low range order of the nanocomposites.     

N2O5/HNO3体系中硝解DADN的反应动力学

采用高效液相色谱跟踪检测了不同温度条件下N₂O₅/HNO₃体系硝解DADN时反应底物、中间体和产物浓度随时间的变化情况。通过对303、313、323、333 K温度下实验数据的分析,计算得到各步的反应速率常数,并最终求得DADN到SEX和SEX到HMX两步的反应活化能分别为2.3996×10⁴ J·mol^-1和1.6598×10⁴ J·mol^-1,指前因子分别为2.2000×10⁴ h^-1和6.5178×10² h^-1。同时,通过柱分离得到的中间产物经结构鉴定为SEX,对其硝基机理进行了分析,实验证明DADN的硝解反应分两步进行,是一级连串反应过程,控制步骤是SEX到HMX。     

Photocatalytic degradation of omethoate using NaY zeolite-supported TiO2

The degradation of omethoate was conducted using H₂O₂ as oxidant, TiO₂ supported on NaY zeolite as photocatalyst and a 300W lamp as light source. The effect of the calcination temperature of the photocatalyst, the amount of TiO₂ loaded on NaY zeolite, the photocatalyst amount, the pH value and the radiation time on the degradation ratio of omethoate were investigated. The results show that TiO₂/NaY zeolite photocatalyst prepared by sol-gel method had good photocatalysis. The photocatalytic optimum oxidation conditions of omethoate are as follows: the calcination temperature of the photocatalyst is 550°C,the amount of TiO₂ loaded on NaY zeolite is 35.2 wt-%, the amount of photocatalyst is 5 g/L, pH = 8 and the radiation time is 180 min. Under these conditions, the removal ratio of omethoate is up to 93%.     

Enhancement of the visible light photocatalytic performance of C-doped TiO2 by loading with V2O5

V₂O₅ was loaded on the surface of C-doped TiO₂ (C-TiO₂) by incipient wetness impregnation in order to enhance the visible light photocatalytic performance. The physicochemical properties of the C-TiO₂/V₂O₅ composite were characterized by XRD, Raman, TEM, XPS, UV–vis diffuse reflectance spectra, and PL in detail. The result indicated that a heterojunction between C-TiO₂ and V₂O₅ was formed and the separation of excited electron–hole pairs on C-TiO₂/V₂O₅ is greatly promoted. Thus, this composite photocatalyst exhibited enhanced visible light photocatalytic activity in degradation of gas-phase toluene compared with the pristine C-TiO₂.