流化床气相水解制备高纯二氧化钛

针对TiCl_4气相水解制备TiO_2粉体存在Cl含量高的问题,开展了流化床TiCl_4气相水解制备高纯TiO_2。系统地研究了反应条件、煅烧后处理对TiO_2粉体的纯度、形貌、晶型、比表面积的影响。结果表明,TiO_2内部结构和晶型的转变有利于Cl的脱除;提高煅烧温度使TiO_2的内部结构由多孔疏松向致密结构转变,晶型结构由锐钛矿相向金红石相转变,从而有利于提高Cl的脱除率;与空气煅烧比较,水蒸气气氛下的脱氯效率明显提高,归因于水蒸气与TiO_2颗粒内残余的多羟基氯化物进一步反应;氢气气氛下可进一步提高Cl的脱除率,800℃煅烧2 h后Cl的脱除率达到95%,主要归因于氢气还原TiO_2使其晶型结构发生转变。     

TiO2晶型对微波加热制备TiB2粉体的影响

为探究TiO₂晶型(锐钛矿型和金红石型)对微波加热制备TiB₂粉体的影响,分别以锐钛矿型和金红石型TiO₂为钛源,B₄C为硼源,炭黑为碳源,在微波加热的条件下通过硼热/碳热还原法快速制备了TiB₂粉体,探讨了TiO₂晶型对微波加热制备TiB₂粉体的物相组成、显微结构以及C和O杂质含量的影响。结果表明：在微波加热条件下,2种晶型TiO₂原料在1 450℃反应20 min后均可制备纯相TiB₂粉体,其中金红石型TiO₂制备的TiB₂粉体呈规则的六方片状结构,晶粒发育较为完善。而锐钛矿型TiO₂制备的TiB₂则为近似球状结构。相比较,金红石型TiO₂作为硼源更有利于制备高纯度、晶型完整的TiB₂粉体。     

煅烧温度对Fe/TiO2复合粉体光催化性能的影响

采用溶胶-凝胶法制备合成Fe/TiO₂纳米复合粉体,用紫外光照射甲基橙溶液的降解实验,通过降解率比较粉体的光催化性能。通过XRD、SEM、UV-Vis等分析手段对粉体的结构和光学性能进行了表征。结果表明,不同的煅烧温度对TiO₂粉体的光催化性能有显著影响,随着煅烧温度的升高,逐渐向金红石相发生转变;450℃的煅烧条件下,甲基橙的降解率最好。     

Ti/nanoTiO2-ZrO2修饰电极电催化氧化葡萄糖

在无水乙醇和乙酰丙酮混合溶液中,电解Ti金属制得前驱体Ti（OCH₂CH₃）_（4-y）（acac）_y,再加入ZrCl₄,将上述溶液直接水解、干燥后在450℃煅烧2 h,粉体通过X射线衍射（XRD）分析表明：纳米TiO₂-ZrO₂粉体呈单分散结构。通过凝胶涂抹、煅烧得到高活性的     

TiO2、ZnO和TiO2/ZnO三种氧化物粉体材料的抗菌性能对比

氧化物具有化学性质稳定、原材料丰富易得的优点,其作为抗菌材料日益受到关注。对氧化物的抗菌性能及影响因素开展深入研究,能够为新型抗菌材料的开发提供科学依据。通过溶胶-凝胶法制备出了TiO₂/ZnO复合粉体,并将其与TiO₂、ZnO进行对比,分别对它们的晶相结构、微观形貌和粒径进行了表征。利用大肠杆菌ATCC25922作为受试菌株,通过抑菌环试验和菌液接触试验对3种氧化物粉体材料的抗菌性能进行测试。考察了钛锌比、光照等条件对抗菌效果的影响。结果表明,所使用的TiO₂主要由锐钛矿相和金红石相组成,ZnO主要为六方纤锌矿相,制备出的TiO₂/ZnO则主要是锐钛矿型TiO₂在六方纤锌矿型ZnO的孔隙间沉积而成,这3种粉体材料的粒径由大到小分别为TiO₂/ZnO、TiO₂和ZnO。从抑菌环和菌液接触试验的结果可以看出,ZnO粉体材料的抗菌效果明显优于TiO₂粉体材料,ZnO和TiO₂/ZnO在黑暗条件下仍有良好的抗菌性能,但在可见光照射条件下抗菌效果更佳。ZnO含量是TiO₂/ZnO复合材料抗菌性能的关键因素。制备TiO₂/ZnO粉体材料时的煅烧温度对其抗菌性能没有明显影响。     

不同晶型TiO2消光PET的流变性能研究

分别以金红石型二氧化钛(TiO₂)粉体和锐钛矿型TiO₂粉体为消光剂,通过原位聚合制备不同TiO₂粉体含量的消光聚对苯二甲酸乙二醇酯(PET),研究了不同晶型TiO₂消光PET的流变性能。结果表明:在剪切速率()为4000~7000 s^-1,金红石型TiO₂和锐钛型TiO₂消光PET熔体的表观黏度(η_a)随的变化幅度均较小,均具有良好的纺丝稳定性;相同温度下,金红石型TiO₂消光PET的非牛顿指数(n)小于锐钛型TiO₂消光PET,但随着温度升高,金红石型TiO₂消光PET的n上升幅度大,其η_a对变化更为敏感;在常规纺丝条件下,金红石型TiO₂消光PET的黏流活化能(E_η)明显小于锐钛型TiO₂消光PET,TiO₂含量较低时金红石型TiO₂消光PET的η_a对温度变化的敏感程度较小;相同温度下,金红石型TiO₂消光PET熔体的结构黏度指数(η)高于锐钛型TiO₂消光PET;在纺丝温度有波动的情况下,金红石型TiO₂消光PET可纺性好,但其纺丝工艺窗口较窄,应采用更高的纺丝温度以获得良好的纺丝效果。     

层序空间多孔结构TiO2实现高效光催化CO2还原

以葡萄糖为原料，经一步水热法生成葡萄糖基碳球(GCs)，粒径约500nm，利用微乳液聚合法合成粒径约270nm的聚苯乙烯微球(PSs)。通过真空抽滤，制备了GCs和PSs层层组装的多级模板，TiCl₄完全浸润模板并经干燥和高温煅烧，获得了空间层序多级孔结构的TiO₂。采用X射线衍射(XRD)、扫描电子显微镜(SEM)、N₂吸附-脱附等手段表征了所制备催化剂的形貌、组分和孔结构。在饱和CO₂气氛下加入H₂O，利用催化剂在模拟太阳光条件进行光催化还原试验。结果表明：经过7h的光催化测试，相较于商用P25和无空间结构的TiO₂，层序空间多孔TiO₂生成还原产物CO的产率均得到明显提高。其中，空间复合多级孔TiO₂在结构失配的情况下仍表现出较高的CO产率。结合实验结果和表征证实：纳米微球层所形成的层序空间多孔TiO₂具有较高的比表面积和丰富的孔结构，有利于形成大量表面活性位点。三维网状多孔结构暴露出...     

超临界干燥法制备TiO2/凹凸棒复合光催化剂

以凹凸棒为载体,四氯化钛为钛源,通过溶胶-凝胶法结合超临界干燥法制备TiO₂/凹凸棒复合光催化材料。采用XRD、SEM、TEM、BET、XPS等方法对材料的结构、形貌及催化性能进行表征。研究结果表明：超临界干燥可增大复合材料的比表面积,抑制TiO₂发生晶型转变。凹凸棒吸附特性良好,增加了材料表面的活性位点,显著提高催化剂的光催化活性。不同煅烧温度下的TiO₂均为锐钛矿型,粒径约为20 nm,呈不规则短棒状,成功负载于凹凸棒上。在400℃煅烧2 h条件下,催化剂3 h后对亚甲基蓝的降解率可达98.4%。     

色氨酸辅助合成光催化活性增强的球形纳米TiO2

以L-色氨酸（L-Trp）为生物模板,采用简单水解及煅烧后制备了球形结构TiO₂纳米光催化剂。通过X射线衍射、扫描电子显微镜、红外光谱、紫外-可见漫反射光谱、光致发光光谱和N₂吸附-解吸等方法对制得的TiO₂纳米材料进行表征。在催化剂合成过程中,L-Trp作为生物模板发挥至关重要的作用,能够指导球形结构纳米TiO₂的形成。考察了不同煅烧温度下制备的TiO₂样品光催化活性,结果表明550℃时制备的TiO₂样品具有优异的光催化活性,紫外光照射30min对甲基橙溶液的降解率达到95%左右,主要是由于较大比表面积和球形结构的协同效应。光催化剂稳定性实验表明,所制备的TiO₂纳米材料可作为一种实用有效的光催化剂用于紫外光照射下降解有机染料。同时,对L-Trp辅助下球形结构TiO₂纳米颗粒的可能生长机理进行讨论。     

烟气中水蒸气对钙基吸收剂碳酸化的影响特性

在循环煅烧/碳酸化反应系统上考察煅烧气氛和碳酸化气氛中水蒸气含量以及CO₂分压对钙基吸收剂成型颗粒碳酸化的影响,通过对钙基吸收剂微观结构分析(扫描电镜、氮吸附分析)以理解水蒸气影响碳酸化特性的机理。结果表明,煅烧气氛和碳酸化气氛中的水蒸气均可提高钙基吸收剂的碳酸化转化率,水蒸气含量分别为10%和5%时,吸收剂的碳酸化性能较好;水蒸气在碳酸化气氛中对高铝水泥改性吸收剂的改善作用较石灰石显著。煅烧气氛中的CO₂分压越高,烧结现象越严重,降低钙基吸收剂的捕集效率;碳酸化气氛CO₂分压提高,有利于提高钙基吸收剂的碳酸化转化率。烟气中水蒸气丰富了吸收剂的微观孔隙,使得吸收剂捕集CO₂性能得到改善。     

TiO2与SiO2掺杂对Al2O3相转变的研究

通过球磨混合法,制备TiO2、SiO2和TiO2+SiO2掺杂的Al2 O3粉体,经不同温度煅烧后进行X射线衍射(XRD)测试,比较研究这三种掺杂对Al2 O3粉体相转变温度的影响.研究结果表明,TiO2、SiO2掺杂对γ-Al2 O3向α-Al2 O3的相转变均有促进作用.在掺杂质量分数为0.5％的情况下,二者可分别...     

Preparation and characterization of nitrogen-doped mesoporous titania with high specific surface area

Nitrogen-doped mesoporous titania aerogel photocatalysts were prepared by supercritical drying technique with carbon dioxide (SCCO₂) and calcination the urea impregnated TiO₂ aerogel at 773 K under NH₃ or N₂ + NH₃aq gaseous atmosphere. The pore properties were investigated from nitrogen adsorption measurement at 77 K. The prepared N-doped TiO₂ aerogel had a high specific surface area (116 m²/g), a total pore volume (0.33 cm³/g) and a sharp pore radius distribution (r_peak = 4.2 nm). The doping of the nitrogen atom into the TiO₂ lattice is expected from X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD), and UV–Vis spectroscopy. Nitrogen states in the lattice and crystalline structure were measured using X-ray photoelectron spectroscopy and X-ray diffractometry. The N-doped TiO₂ aerogel absorbed well into the visible region up to 600 nm.     

Dielectric behavior of Nb2O5-doped TiO2/epoxy thick films

TiO₂/epoxy composite thick films containing the TiO₂ powders doped with 4 and 10 vol% Nb₂O₅ heat treated under vacuum at 1050 and 1150 °C, were prepared by the screen printing and curing steps. The Nb₂O₅-doped TiO₂ ceramic bulks demonstrated a higher effective dielectric constant at different densification environments, as compared with pure TiO₂. The dielectric properties of the TiO₂/epoxy thick films were improved if the heat-treated 4 vol% Nb₂O₅-doped TiO₂ powder was incorporated instead of the un-doped and heat-treated 10 vol% Nb₂O₅-doped TiO₂ powders. The disadvantage of the doped TiO₂ having higher dielectric loss tangent could be minimized after its powder was properly treated and mixed with epoxy to form the TiO₂/epoxy composite. A best result with the dielectric constant of 23 and the loss tangent of 0.046 was obtained for the 40 vol% TiO₂/epoxy composite thick films, where the TiO₂ powder was doped with 4 vol% Nb₂O₅ followed by calcination at 1000 °C in air and heat treatment at 1150 °C under vacuum.     

Characterization and photocatalytic activity of N-doped TiO2 prepared by thermal decomposition of Ti–melamine complex

Nitrogen doped spherical TiO₂ has been prepared by thermal decomposition of Ti–melamine complex in air atmosphere. A clear shift in the onset light absorption from UV region (<400) to visible region (>520 nm) has been observed for the N-doped samples. It has been deduced from the optical absorption spectra that the higher calcination temperature results in the decrease in the amount of N-doping. The XRD results revealed the phase transition of TiO₂ from anatase to rutile crystalline phase, starting at calcination temperature ≥600 °C. The electron microscopic images reveal the formation of spherical and flakes of TiO₂ nanocrystals (25 nm). The chemical nature of N in the N-TiO₂ has been evolved through X-ray photoelectron spectroscopy. The presence of different types of N species have been observed corresponding to different oxidation states and the presence of Ti–N and O–Ti–N have been confirmed from the observed binding energy values. Photocatalytic decomposition of methylene blue has been carried out both in the visible region and UV + visible region. In the visible region, N-TiO₂ showed higher activity compared to the undoped commercial TiO₂ (Degussa P25).     

TiO2 coating types influencing the role of water vapor on the photocatalytic oxidation of methyl ethyl ketone in the gas phase

Four TiO₂-based materials, named A, B, C and D, are used to investigate the influence of water vapor on the gas–solid adsorption and heterogeneous photocatalytic oxidation of gaseous methyl ethyl ketone (MEK). Two of the photocatalysts (A and B) are constituted of powdered TiO₂ deposited onto two different supports (ordinary glass and non-woven cellulose fibers). The other ones (C and D) are composed of a thin film of TiO₂ coated on glass substrates. The effect of water vapor on MEK initial conversion rates is studied for the four photocatalytic materials using the Langmuir–Hinshelwood model at the initial time. On the concentrations range where the model hypotheses are verified, adsorption constants K and kinetics constants k are calculated for experiments under both dry and humid atmosphere. When the relative humidity is increased, the evolution of these constants shows that water vapor acts differently depending on the form of deposited TiO₂ (powder and film).     

阵列型TiO2纳米管光催化降解VOCs性能

通过二次阳极氧化电化学方法制备纳米孔/纳米管复合结构的阵列型TiO₂纳米管（2-step TiO₂ NTs）,实验证明这种结构的TiO₂ NTs对大气中的挥发性有机化合物（volatile organic compounds,VOCs）有着十分优异的降解效果。本文通过气态甲醇的光催化降解来评估比较一次氧化生成的TiO₂纳米管（1-step TiO₂ NTs）和2-step TiO₂ NTs的催化效果。实验结果表明,二次阳极氧化电化学方法所生成的TiO₂ NTs的纳米结构对光致电荷的产生有着十分重要的推动作用。之所以2-step TiO₂ NTs的纳米孔/纳米管复合结构能够显著提高VOCs的降解效率,是由于这种特殊的结构能够更加有利于电子的传递,同时能够有效地抑制光生电子和空穴的复合。最后,通过实验数据阐述了2-step TiO₂ NTs光催化活性的增强机理,这种新结构显示出更小的带隙、更高效的光生电子/空穴分离效率和VOCs降解性能。     

H2气氛中TiOx的形成及其对Ni/TiO2催化剂顺酐液相加氢性能的影响

采用等体积浸渍法制备了Ni/TiO₂催化剂,利用N₂物理吸附、H₂-TPR、XRD、H₂-TPD及CO-TPSR等表征手段研究H₂气氛中随着热处理温度升高,Ni/TiO₂催化剂结构和织构变化规律,并考察催化剂的顺酐液相加氢性能。研究表明,随着热处理温度的升高,催化剂C-C键加氢活性逐渐增高,而CO加氢活性先增高后降低。产生这一现象的原因与TiO_x物种随H₂气氛中热处理温度的升高而逐渐增多有关。     

Synthesis of nanosized TiO2/SiO2 particles in the microemulsion and their photocatalytic activity on the decomposition of p-nitrophenol

Nanosized pure TiO₂ particles were prepared by hydrolysis of TTIP in the sodium bis(2-ethylhexyl)sulfosuccinate (AOT) reverse micelles. TiO₂/SiO₂ nanoparticles were also prepared from TEOS as a silicon source and TTIP as a titanium source. These particles were characterized by TEM, XRD, FT-IR, BET, TGA and DTA. From thermal analysis and XRD analysis, the anatase structure of pure titania appeared in the 300–600 °C calcination temperature range and the rutile structure was showed above 700 °C. However, no rutile phase was observed for the TiO₂/SiO₂ particles up to 800 °C. The crystallite size decreased and the surface area of TiO₂/SiO₂ particles monotonically increased with an increase of the silica content. From FT-IR analysis, the band for Ti–O–Si vibration was observed and the band intensity for Si–O–Si vibration increased with an increase of the silica content. The micrographs of TEM showed that the TiO₂/SiO₂ nanoparticles had a spherical and a narrow size distribution. In addition, TiO₂/SiO₂ particles showed higher photocatalytic activity than pure TiO₂ and the TiO₂/SiO₂ (90/10) particles showed the highest activity on the photocatalytic decomposition of p-nitrophenol.     

煅烧温度对Mo-Mn/TiO2催化剂脱硝脱汞活性的影响

研究了浸渍法制备Mo-Mn/TiO₂（MMT）催化剂过程中煅烧温度（300℃、450℃、600℃、750℃）对Mo-Mn/TiO₂（MMT）催化剂协同脱硝脱汞活性的影响。结果表明,较低的煅烧温度更有利于MMT催化剂的协同脱硝脱汞性能,同时可有效降低SO₂对催化剂活性的抑制作用,最佳煅烧温度为300℃。利用BET、XRD、H₂-TPR、FTIR和XPS等表征手段对催化剂的理化性质进行了表征,结果表明较低的煅烧温度有利于提高催化剂中活性成分所占的比例,增加金属氧化物在TiO₂载体表面的分散度,提高催化剂的低温还原性能。随着煅烧温度的升高,催化剂的比表面积和孔容均逐渐减小,平均孔径先增大后减小,且在高温下发生烧结;MnO₂逐渐向Mn₂O₃转变,锐钛矿型TiO₂逐渐向金红石型转变,同时MoO₃由非晶态逐渐向晶态的转化,致使催化剂的协同脱硝脱汞活性下降。