Effects of silica additive on the NH_3-SCR activity and thermal stability of a V_2O_5/WO_3-TiO_2 catalyst

V2O5/WO3‐TiO2 and V2O5/WO3‐TiO2‐SiO2 catalysts were prepared by a wetness impregnation method, and both the catalysts were hydrothermally aged at 750℃ in 10 vol%H2O/air for 24 h. The catalysts were evaluated for NOx conversion using NH3 as the reductant. Hydrothermal ageing decreased the NOx conversion of V2O5/WO3‐TiO2 catalyst severely over the entire measured tem‐perature range. Interestingly, the NH3‐SCR activity of the silica‐modified catalyst at 220–480℃ is enhanced after ageing. The catalysts were characterized by X‐ray diffraction, nitrogen adsorption, X‐ray fluorescence, Raman spectroscopy, H2 temperature‐programmed reduction, and NH3 temper‐ature‐programmed desorption. The addition of silica inhibited the phase transition from anatase to rutile titania, growth of TiO2 crystallite size and shrinkage of catalyst surface area. Consequently, the vanadia species remained highly dispersed and the hydrothermal stability of the V2O5/WO3‐TiO2 catalyst was significantly improved.

WO_3-TiO_2复合光催化材料的水热合成及其光催化性能

以无水Ti(SO4)2和Na2WO4为原料,采用一步水热法制备了WO3-TiO2复合光催化材料。利用X射线衍射(XRD)、红外光谱(FT-IR)、扫描电子显微镜(SEM)和紫外-可见吸收光谱(UV-Vis)对复合材料的结构和性质进行了表征。研究了WO3-TiO2复合材料对罗丹明B的光催化降解能力,结果表明,可见光(高压汞灯)照射下,WO3-TiO2复合材料的光催化性能优于P25粉末以及相同条件下制备的TiO2粉末,0.1g WO3-TiO2粉末(WO3摩尔分数2%)对20mL罗丹明水溶液(1×10-5 mol/L)进行光催化降解,5h后降解率达到了98.09%。

WO_3-TiO_2/SBA-15的制备及其光催化氧化脱硫性能

采用孔道内水解法制备了WO_3-TiO_2/SBA-15催化剂用于光催化氧化柴油脱硫,利用XRD、SEM、EDS、N2吸附-脱附、FT-IR、TG-DTA和UV-vis等技术对该催化剂进行了表征,考察了WO_3和TiO_2负载量、焙烧温度和焙烧时间对其光催化氧化脱硫性能的影响。结果表明,WO3和Ti O2负载量分别为1.6%和15%,焙烧温度500℃,焙烧时间为3 h条件所制备的催化剂性能最佳;在该条件下制备的WO_3-TiO_2/SBA-15催化剂仍保持SBA-15的六方介孔结构,模拟柴油的脱硫率高达87.9%,且具有良好的回收再生性能。

Sol-gel法制备介孔WO_3-TiO_2复合材料及其光催化性能

以非离子表面活性剂P123为结构导向剂,采用溶胶-凝胶法,通过调整P123与(W+Ti)的摩尔比例,经500℃煅烧制备出一系列不同介孔特性的WO3-TiO2复合光催化材料。利用X射线衍射图谱(XRD)、扫描电子显微镜(SEM)、紫外-可见吸收光谱(UV-Vis)、比表面积分析仪(BET)对复合材料的形貌、孔结构及光谱性质进行表征。研究了介孔WO3-TiO2复合材料对罗丹明B的吸附/光催化降解能力。结果表明,以P123为模板剂所制备的介孔WO3-TiO2复合材料表现出较好的吸附/光催化性能,可见光照射下,0.5g的P123、(W+Ti)摩尔比为0.6%的复合材料经500℃煅烧,对200mL罗丹明B(10mmol/L)的吸附降解率140min后达到97.7%。

锰掺杂WO_3-TiO_2复合光催化剂的制备及其性能研究

溶胶-凝胶和浸渍相结合的方法制备锰掺杂WO3-TiO2复合光催化剂,RXD表征,考察WO3和Mn2+掺入量、焙烧温度、焙烧时间及催化剂用量对光催化降解甲基橙的影响。结果表明,500℃焙烧2 h,掺杂量n(Mn2+)∶n(WO3)∶n(TiO2)=0.8∶1∶100时,光催化活性最高,光催化降解甲基橙溶液,120 m in后,降解率达90%,比单纯TiO2的光催化活性提高81%。

负载型纳米复合半导体WO3-TiO2／AC光催化降解刚果红废水

采用溶胶-凝胶-浸渍-焙烧法制备了负载型纳米复合半导体WO3-TiO2/AC光催化剂,以偶氮染料刚果红为目标降解物,通过正交实验优化了刚果红废水的降解条件,并对其光催化动力学进行了探讨。结果表明,刚果红废水的最佳降解条件为:催化剂投加量10 g/L,pH=7,H2O2用量为3.5 mL/L。在最佳条件下,当刚果红废水起始浓度为40 mg/L时,反应120 min后,刚果红溶液的去除率可达95.21%,较相同条件下TiO2/AC对刚果红染料的降解率提高了19.57%。光催化剂对刚果红的光催化降解符合Langmuir-Hinshelwood(L-H)模型。

超声场作用下薄膜型WO_3-TiO_2光催化剂制备与性能表征

在超声场作用下采用溶胶-凝胶法制备了纳米WO3-TiO2复合光催化剂。利用薄膜对罗丹明B溶液的光催化降解作用,考察了钨酸铵掺杂量、镀膜层数、烧结温度、烧结时间、基质、pH值、溶解氧及超声波等因素对光催化活性的影响,并与普通溶胶-凝胶法进行了比较。结果表明,在超声场作用下,溶胶的胶凝时间显著缩短,光催化剂颗粒粒径明显减小,催化活性显著提高,当钨酸铵掺杂量为0.5%(质量分数)、多孔钛片为基质、镀膜9层、575℃下烧结1 h得到的WO3-TiO2薄膜的光催化活性最高。该温度下制备的WO3-TiO2薄膜几乎均为金红石型TiO2。

Photoelectrocatalytic reduction of CO_2 into formic acid using WO_(3-x)/TiO_2 film as novel photoanode

A novel WO3-x/TiO2 film as photoanode was synthesized for photoelectrocatalytic（PEC） reduction of CO2 into formic acid（HCOOH）. The films prepared by doctor blade method were characterized with X-ray diffractometer（XRD）, scanning electron microscope（SEM） and transmission electron microscope（TEM）. The existence of oxygen vacancies in the WO3-x was confirmed with an X-ray photoelectron spectroscopy（XPS）, and the accurate oxygen index was determined by a modified potentiometric titrimetry method. After 3h of photoelectrocatalytic reduction, the formic acid yield of the WO3-x/TiO2 film is 872 nmol/cm^2, which is 1.83 times that of the WO3/TiO2 film. The results of PEC performance demonstrate that the introduction of WO3-x nanoparticles can improve the charge transfer performance so as to enhance the performance of PEC reduction of CO2 into formic acid.

TiO2-Loaded WO3 Composite Films for Enhancement of Photocurrent Density

Titanium dioxide （TiO2） loaded tungsten trioxide （WO3） composite films are prepared by an E-beam vapor system. Associated with the existence of a heterojunction at the interface of TiO2 and WO3, the prepared TiO2-WO3 composite film shows enhanced photocurrent density, four times than the pure WO3 film illuminated under xenon lamp, and higher incident-photon-to-current conversion e^ciency. By varying the initial TiO2 film thickness, such composite structures could be optimized to obtain the highest photocurrent density. We believe that thin TiO2 films improve the light response and increase the surface roughness of WO3 films. Furthermore, the existence of the heterojunction results in the e^cient charge carriers＇ separation, transfer process, and a lower recombination of electron-hole pairs, which is beneficial for the enhancement of photocurrent density.

WO_3-TiO_2/SBA-15的光催化氧化柴油脱硫性能

以钛酸四正丁酯为钛源、钨酸钠为钨源、SBA-15为催化剂载体,采用孔道内水解法制备WO_3-TiO_2/SBA-15样品,并用XRD、BET对其进行表征,并将其应用于模拟柴油的光催化氧化脱硫实验,考察催化剂用量、n(O)/n(S)、反应温度、反应时间等对光催化氧化脱硫的影响。结果表明:在催化剂用量为4g/L、n(O)/n(S)为8、反应温度为50℃、反应时间为2h的条件下,模拟柴油的脱硫率可达87.9%,催化剂重复使用5次后脱硫率仍可达到64.9%。表明WO_3-TiO_2/SBA-15催化剂具有较好的光催化氧化脱硫性能和再生性能。

WO_3-TiO_2-ZnO溶胶的制备及其光致变色性能研究

采用溶胶-凝胶法分别制备了WO3,TiO2和ZnO溶胶,在此基础上以一定比例混合后形成WO3-TiO2-ZnO和WO3-TiO2溶胶。利用透射电镜和紫外-可见分光光度计对其进行了表征。结果表明,WO3-TiO2-ZnO溶胶粒子尺寸分布在10~25nm范围,WO3-TiO2-ZnO溶胶比WO3溶胶和WO3-TiO2溶胶具有更好的光致变色性能。用500W汞灯照射80s后,WO3-TiO2-ZnO溶胶由无色变为蓝色,变色后的溶胶在无光照6h左右后由蓝色恢复到无色,具有很好的光致变色行为的可逆性。

WO_3-TiO_2纳米复合光催化剂的制备及其对曙红Y的光催化降解

通过溶胶-凝胶法制取掺杂三氧化钨的纳米TiO2复合光催化剂,并通过对染色剂曙红Y进行光催化降解,讨论催化剂用量、加入氧化剂H2O2量等因素对光催化剂降解效率的影响。研究结果表明:在酸性环境的条件下,加入催化剂量为0.15g、双氧水用量为2mL时复合光催化剂有较好降解效果。

WO_3-TiO_2光阳极的制备及其光解水制氢性能研究

以钛酸四丁酯和钨酸钠为主要原料,采用溶胶-凝胶法制备了WO_3-TiO_2复合光阳极,WO_3所占的质量分数分别为0.5%、1%、2%和3%。采用XRD和SEM表征了WO_3-TiO_2光阳极的结构,研究了WO3掺杂、热处理温度对薄膜结构和光解水制氢性能的影响。结果表明,WO_3掺杂提高了TiO_2光阳极的光解水制氢速率。当WO_3掺杂量为2%、热处理温度为400℃、WO_3-TiO_2复合光阳极为高结晶度的锐钛矿晶型时,光催化活性最好,光解水制氢速率为5.8μmol/h。

半导体表面化学沉积制备WO3-TiO2薄膜的组织及电化学性能

采用化学沉积制备方法,添加不同的封端剂(十二烷基苯磺酸钠SDBS或聚乙二醇PEG)制备得到半导体用纳米WO3-TiO2薄膜,并表征该材料的电致变色性能。研究结果表明:加入SDBS的WO3-TiO2薄膜相邻片之间有较大间隙,形成了众多裂纹并发生了颗粒团聚现象。所有WO3-TiO2薄膜试样在着色态条件下透射光谱曲线发生了短波偏移。添加PEG的WO3-TiO2薄膜的着色态与褪色态并没有出现透过率显著改变的情况,综合选择SDBS作为薄膜封端剂时可以获得更优的变色效果。在相同时间中以SDBS作为封端剂来制得的WO3-TiO2薄膜形成了比利用PEG作为封端剂制得的WO3-TiO2薄膜更大的电流密度,且可以获得更多离子注入,及薄膜着色与褪色电流的稳定性更优。

WO_3-TiO_2复合空心球的制备及其光催化性能

以钛酸四正丁酯和偏钨酸铵为原料,采用水热-模板法制备复合WO3-TiO2光催化剂。利用X射线衍射（XRD）、扫描电子显微镜（SEM）、比表面积（BET）和紫外-可见漫反射（UV-Vis DRS）等手段对催化剂的结构和光学性能进行表征。结果表明：WO3-TiO2复合半导体中的TiO2为锐钛矿晶型,焙烧后的WO3-TiO2呈中空球形结构,粒径在320 nm左右,且粒径分布均匀,其比表面积和平均孔径分别为40.95 m2/g和16.91 nm,WO3-TiO2复合半导体的紫外-可见吸收边带较TiO2的红移约50 nm,并在400~500 nm处有吸收。光降解甲基橙（MO）实验显示：经过80 min光照后,WO3-TiO2复合半导体在紫外和可见光下对甲基橙的降解率分别为99.2%和81%,而TiO2的仅为64%和25%,且在紫外和可见光下WO3-TiO2复合半导体的表观速率常数分别是TiO2的3.2和4.9倍左右。

WO_3-TiO_2-SO_4^(2-)固体超强酸合成柠檬酸三丁酯

用TiO2 ·nH2 O和H2 WO4混合 ,其中w(H2 WO4) =10 % ,然后用c(H2 SO4) =1mol/L的溶液浸渍 ,在 5 5 0℃焙烧 2h ,可制得Ho≤ - 14 .5 2的WO3 TiO2 SO42 -固体超强酸催化剂 ,用于柠檬酸和正丁醇的酯化反应 ,实验结果表明最佳反应条件为 :反应温度 15 5℃ ,醇酸物质的量比为 3.9∶1,反应时间 4h ,催化剂用量占总投料质量的 1.5 % ,柠檬酸的转化率达 98%。

WO_3-TiO_2-SO_4^(2-)固体超强酸的制备及应用研究

TiO2 ·nH2 O和H2 WO4 混合 ,其中w(H2 WO4 ) =10 % ,然后用c(H2 SO4 ) =1mol/L的溶液浸渍 ,在 6 0 0℃焙烧 3h ,可制得Ho≤ - 14 5 2的WO3 TiO2 SO4 2 -固体超强酸。其w(SO3) =4 7% ,总酸量为 0 85mmol/g ,比表面积为 110m2 /g。用其催化乙酸丁酯液相酯化反应 ,乙酸转化率可达 96 %

WO_3-TiO_2复合材料的制备及其光催化应用研究进展

TiO_2被认为是一种应用于分解有机污染物和裂解水制氢较好的光催化剂,但由于其较宽的禁带宽度,使得其只能吸收紫外光才能激发光催化活性。将禁带宽度较窄的WO_3与TiO_2复合后可以有效地提高在可见光下的光催化活性。主要介绍了近几年来WO_3-TiO_2复合材料制备方法,以及其在光催化降解及水制氢方面的应用,最后展望了该复合材料的发展方向。

WO_3-TiO_2/C@Fe_3O_4纳米复合粉体的制备及对甲基橙的太阳光催化降解

以纳米Fe_3O_4粉体为原料与葡萄糖溶液采用高压水热反应制备C@Fe_3O_4纳米载体,并以其为核采用溶胶-凝胶法制备了WO_3-TiO_2/C@Fe_3O_4纳米复合粉体.通过X射线衍射(XRD)、傅立叶红外光谱(FT-IR)、透射电镜(TEM)等进行了表征,并测定了其对甲基橙溶液的太阳光催化性能.结果表明,pH=5时,WO_3-TiO_2/C@Fe_3O_4纳米复合粉体对甲基橙的催化活性最高,太阳光照射6 h后降解率达到45.3%,并能实现粉体与甲基橙溶液的有效分离.

Anticorrosion of WO₃-Modified TiO₂Thin Film Prepared by Peroxo Sol-Gel Method

The aim of this study was to develop a method to prepare WO3-TiO2 film which has high anticorrosion property when it was coated on type 304 stainless steel. A series of WO3-modified TiO2 sols were synthesized by peroxo-sol gel method using TiCl4 and Na2WO4 as the starting materials. TiCl4 was converted to Ti(OH)4 gel. H2O2 and Na2WO4 were added in Ti(OH)4 solution and heated at 95°C. The WO3-TiO2 sol was transparent, in neutral (pH^7) solution, stable suspension without surfactant, nano-crystallite and no annealing is needed after coating, and very stable for 2 years in stock. WO3-TiO2 sol was formed with anatase crystalline structure. These sols were characterized by XRD, TEM, and XPS. The sol was used to coat on stainless steel 304 by dip-coating. The WO3-TiO2 was anatase in structure as characterized by X-ray diffraction. There were no WO3 XRD peaks in the WO3-TiO2 sols, indicating that WO3 particles were very small, possibly incorporating into TiO2 structure, providing the amount of WO3 was very small. The TiO2 particles were rhombus shape. WO3-TiO2 had smaller size area than pure TiO2. The SEM results showed that the film coated on the glass substrate was very uniform. All films were nonporous and dense films. Its hardness reached 2 H after drying at 100°C, and reached 5 H after annealing at 400°C. The WO3-TiO2 film coated on 304 stainless steel had better anticorrosion capability than the unmodified TiO2 film under UV light illumination. The optimum weight ratio of TiO2: WO3 was 100:4.