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1.
Titania supported samples on different types of silica have been prepared through a sol–gel method followed by hydrothermal processing. The photocatalytic activity of the samples was tested for free cyanides photo-oxidation. As compared to commercial TiO2 all the synthesised materials showed not only similar photocatalytic efficiencies but improved recovery properties. The degradation of iron(III) cyanocomplexes was also studied in the absence or presence of titania catalyst. In all cases, a photoinduced CN− released from the complex takes place through a homogeneous process. The further oxidation of those cyanides ions to cyanate species is significantly enhanced in the presence of the catalyst in which mesostructured SBA-15 silica is used as support. 相似文献
2.
通过溶胶凝胶法,经多次涂覆在SBA-15上负载掺杂镍的纳米TiO2,得到SBA-15/NiO/TiO2复合物;再以TiO2中还原态金属镍为催化剂,通过化学气相沉积法(CVD),在SBA-15/NiO/TiO2表面原位生长碳纳米管,制得SBA-15/Ni/TiO2/CNTs复合材料。通过XRD、SEM、TEM、UV-Vis和Raman等方法考察了SBA-15/Ni/TiO2/CNTs复合材料的结构和性能,并通过降解亚甲基蓝溶液评价其光催化活性。结果表明,SBA-15/Ni/TiO2/CNTs复合光催化剂的催化活性较SBA-15/NiO/TiO2显著提高。 二次涂覆掺杂镍的二氧化钛制得的复合光催化剂的催化活性高于一次涂覆。 相似文献
3.
Javier Marugn María-Jos Lpez-Muoz Jos Aguado Rafael van Grieken 《Catalysis Today》2007,124(3-4):103-109
The distribution of two different phases in a mixed oxide material could be investigated through several physicochemical characterization techniques. However, the estimation of the fraction of the total surface area corresponding to each oxide is a very difficult task. In this work, we present a novel procedure for the determination of the titanium dioxide surface in titania–silica materials. This new method is based on the measurement of the phosphorus content of the mixed oxide after reaction with phenylphosphonic acid. The quantification of the TiO2 surface has permitted the comparison of the catalytic activity of different materials in processes in which titanium dioxide is the only catalytically active phase and silica behaves as an inert support, as, for instance, in photocatalytic reactions. The activity of several TiO2/SiO2 photocatalysts for cyanide and methanol photooxidation have been analysed and compared with pure TiO2 materials in terms of equal mass of semiconductor, photonic efficiency and active surface area. The results suggest the possibility of achieving surface activity rates even higher than the material Degussa P25 when using nanocrystalline titania supported on silica. 相似文献
4.
在多巴胺修饰的水基TiO_2纳米微粒(TiO_2NPs)悬浮液中,以正硅酸乙酯为硅源,十六烷基三甲基溴化铵为模板剂,分别采用碱性水热方法或酸性溶胶-凝胶方法,制备了有序介孔TiO_2-SiO_2(TiO_2NPs/MCM-41或TiO_2NPs/SBA-3)。采用XRD、TEM、ICP和N2吸附-脱附实验对样品进行表征。结果表明,制备的介孔TiO_2-SiO_2在TiO_2高负载质量分数(23.98%TiO_2NPs/MCM-41、17.27%TiO_2NPs/SBA-3)时,仍能保持长程有序的介孔氧化硅结构。TiO_2NPs随机地嵌入在有序介孔氧化硅孔道所组成的网络结构中。在可见光下催化甲基橙降解反应中,反应时间120 min时,在P25上甲基橙相对浓度降为57%,在TiO_2NPs/MCM-41上降为33%,而在TiO_2NPs/SBA-3上降为5.7%。 相似文献
5.
采用溶胶-凝胶法制备系列BixTi1-xO_2光催化剂以及N和Bi共掺杂Ti O_2光催化剂,采用XRD、UV-Vis、N2-物理吸附和TEM等对催化剂进行微观结构表征,以普通节能灯为光源,考察催化剂光催化氧化室内甲醛的性能。结果表明,在Bi掺杂的Ti O_2光催化剂体系中,Bi0.15Ti0.85O_2光催化剂催化降解甲醛效果最佳,400℃焙烧2.5 h,节能灯光照48 h,可将(1.05±0.05)mg·m-3甲醛降解至0.08 mg·m-3,甲醛转化率92.8%,达到室内空气质量标准。当N与Bi共掺杂时,节能灯光照24 h,Bi0.15Ti0.85O_2-N(0.2)光催化剂表现出最佳的光催化氧化降解甲醛性能,即可将甲醛由(1.05±0.05)mg·m-3降解至0.082 mg·m-3,甲醛转化率达92.0%,较Bi0.15Ti0.85O_2催化剂光催化效率提高50%。 相似文献
6.
O. Guaitella F. Thevenet E. Puzenat C. Guillard A. Rousseau 《Applied catalysis. B, Environmental》2008,80(3-4):296-305
Plasma/catalyst combination is an active solution to reach high conversion rates at low energetic cost. TiO2 is one of the catalysts frequently used in dielectric barrier discharges. Plasma/TiO2 synergy was already exhibited but the mechanisms still have to be understood. This work distinguishes three main effects involved in the synergy: (a) effect of catalyst on the injected power, (b) the effect of porosity on C2H2 oxidation, and (c) the photocatalytic degradation of C2H2 on TiO2 under plasma exposure. Different glass fibres-based catalytic materials coated with SiO2 and/or TiO2 nano-particles are used to separate these three contributions regarding to C2H2 conversion. It is reported that at constant voltage the injected power is mainly increased by the presence of glass fibres. C2H2 oxidation is mainly enhanced by the macroporosity of glass fibres and in a minor way by the nano-particles. The production of O atoms close to the surface is probably responsible for the higher C2H2 removal efficiency with porous material. The photocatalytic activity of TiO2 is negligible in the plasma except if additional UV lamps are used to activate TiO2. With external UV, photocatalytic activity is more efficient in the plasma phase than in a neutral gas phase. This plasma/photocatalysis synergy is due to the use of O atoms in photocatalytic mechanisms. 相似文献
7.
Won Young Jung Seung Hee Baek Jin Sup Yang Kwon-Taek Lim Man Sig Lee Gun-Dae Lee Seong Soo Park Seong-Soo Hong 《Catalysis Today》2008,131(1-4):437-443
Titanium substituted SBA-15 mesoporous materials have been successfully prepared by conventional hydrothermal method and they were also used as support on TiO2 loaded SBA-15 photocatalysts. The synthesized materials were characterized by XRD, UV–vis DRS, FT-IR, BET and TEM. We also examined the activity of these materials as photocatalysts for the decomposition of orange II. The incorporation of titanium into framework of SBA-15 makes the pore diameter and pore volume to decrease and slightly decreases the surface area compared to SBA-15. In addition, the pore size distribution becomes broaden with an increase of titanium amount in the SBA-15 framework. For Ti-SBA-15 and TiO2 loaded Ti-SBA-15 photocatalysts, the IR absorption at 960 cm−1 commonly accepted the characteristic vibration of Ti–O–Si bond. From the TEM images, the regular silica morphology is maintained in the case of Ti-SBA-15(Si/Ti = 50) but the Ti-SBA-15 sample having Si/Ti ratio = 10 partially destroys the hexagonal highly ordered structure and the mesopore structure is disappeared by the clogging of mesopore channels by the titanium dioxides particles for the 50 wt.% TiO2/Ti-SBA-15 samples. The photocatalytic activity increases with an increase of Ti content (decrease of Si/Ti ratio) and with an increase of TiO2 loading content. 相似文献
8.
二维共轭碳材料/TiO2复合光催化剂制备及表征 总被引:1,自引:0,他引:1
选用两种二维共轭碳材料石墨烯(GR)和石墨炔(GD),通过水热合成的方法原位生长制备TiO_2-GR和尿素分散的TiO_2-GR以及TiO_2-GD复合材料光催化剂,对3种复合材料催化剂的表面形貌和物相结构进行表征,并测试3种催化剂光催化剂性能。结果表明,石墨烯和石墨炔的加入,对TiO_2起到明显的分散作用,TiO_2颗粒与石墨烯和石墨炔紧密结合;尿素的加入使TiO_2-GR颗粒尺寸进一步减小,TiO_2分散度进一步提高。在模拟太阳光辐射下,一定时间内光催化剂光降解有机染料亚甲基蓝和甲基橙,结果表明,二维共轭碳材料石墨烯和石墨炔的加入使复合材料光催化剂TiO_2-GR和TiO_2-GD的光催化性能为纯TiO_2光催化剂的1. 67倍和1. 68倍,复合材料光催化剂表现出更优秀的催化性能。 相似文献
9.
Surface bond-conjugated TiO2/SiO2 was prepared by means of the impregnation method. Based on the results of XRD, FTIR, XPS and BET measurements, the growth of titania (predominantly anatase) on the silica substrate seems to occur by anchoring of the TiO2 phase through Ti–O–Si cross-linking bonds. The structure model of TiO2/SiO2 was proposed. Compared to B–TiO2, the most efficient catalyst is 30 wt.% TiO2/SiO2 (Ims30), which showed three times higher photoactivity for the degradation of reactive 15 (R15). In addition, the catalyst had a higher photoactivity on a silica of smaller particle size than on the silica of larger particles. Silica gel plays the basic role of dispersion and support for power TiO2. The isoelectric point of the catalyst was 3.0 pH units by the measurement of zeta-potential, indicating the presence of the surface acidity of the catalyst. The photodegradation and the adsorption of R15 and cationic blue X-GRL (CBX) were investigated with the change of initial aqueous pH. 相似文献
10.
Javier Marugn Dirk Hufschmidt María-Jos Lpez-Muoz Volker Selzer Detlef Bahnemann 《Applied catalysis. B, Environmental》2006,62(3-4):201-207
Hydroxyl radical species are considered to be responsible for many oxidation pathways of chemical compounds initiated by advanced oxidation technologies and particularly in heterogeneous photocatalytic processes. However, not many attempts have been made to quantify the generation rate of these species for newly developed photocatalysts, especially for the large number of supported photocatalysts synthesized during the last years. This work focuses on the evaluation of the photonic efficiency for the hydroxyl radical generation on several silica-supported TiO2 photocatalysts recently developed. The study has been carried out by using methanol as hydroxyl radical scavenger. The influence of the mesoporous structure of the support and of its titania loading on the photonic efficiency of the materials has been analyzed. The importance of diffusional restrictions within the porous structure of the support has also been investigated by using a larger hydroxyl radical scavenger molecule, namely n-butanol. 相似文献
11.
K. Venkata Subba Rao Machiraju Subrahmanyam Pierre Boule 《Applied catalysis. B, Environmental》2004,49(4):239-249
When TiO2 is immobilized on organic fibres, pumice stone or polymer film, the photocatalytic efficiency decreases slowly during long-term use. The efficiency of immobilized photocatalysts were tested on 500 ml of a 5×10−5 M solution of acid orange-7 (a classical azo dye) before and after treatment of 10−3 M solution of acid orange-7 during 4 weeks. It was observed that the efficiency was reduced approximately four, five and 10 times with polymer film containing TiO2, TiO2 on organic fibres and TiO2 on pumice stone, respectively, after 4 weeks of use. Volumes treated were 40, 45 and 60 l, respectively. Nevertheless, the decomposition rate stays a little higher with TiO2 on pumice stone than with the two other catalysts tested. The photocatalytic activity of immobilized TiO2 was significantly reduced also during treated with wastewaters. For immobilized photocatalysts used, the decrease of activity is considered to be caused by the elimination of some particles from the catalyst surface during use and also by fouling of catalyst surface by the formation of by-products during the course of degradation process. 相似文献
12.
T. Docters J. M. Chovelon J. M. Herrmann J. P. Deloume 《Applied catalysis. B, Environmental》2004,50(4):58-226
Titania photocatalysts were synthesised by the molten salts method by reaction of a titanium precursor with three different alkali metal nitrates (LiNO3, NaNO3, KNO3). The titania powders obtained have been characterised using TEM, XRD, BET and UV-Vis absorption spectroscopy. Their photoactivities were evaluated by degrading a commercial sulfonylurea herbicide, Prosulfuron®. It has been found that the rate constants increased in the following order: Li2 prepared in KNO3, with a rate constant 1.4 times smaller than that of P25. The effect of calcination was also studied, especially for the sample prepared in NaNO3 (TiO2[Na]). An improvement in photocatalytic activity was observed when TiO2[Na] was calcined in the region of 700–800 °C. Even though the photocatalytic activities obtained did not exceed or even equal to that of Degussa P25, nevertheless, this study constitutes the first attempt to synthesise titania photocatalysts by the molten salts method. 相似文献
13.
为了提高TiO2的光催化氧化脱硫(PODS)活性,利用负载和复合的协同作用,将TiO2与g-C3N4复合,并负载于双介孔二氧化硅(BMMS)上,制备了TiO2–g-C3N4/BMMS。以含二苯并噻吩(DBT)的十二烷溶液为模拟油,评价了催化剂的催化性能;优化了反应条件并提出了催化反应机理。结果表明:TiO2–g-C3N4/BMMS具有明显的双介孔结构,TiO2与g-C3N4已实现复合并负载于BMMS上,TiO2–g-C3N4活性组分在载体上分散良好,与单一TiO2相比对光的吸收能力增强,催化活性有明显提高,优化后的反应条件为,催化剂用量3%(质量分数),O/S摩尔比为10:1,萃取剂与模拟油体积比为1:1,此时脱硫率可达96.6%,且重复使用8次后脱硫率仍保持85%以上,PODS过程中的主要活性中间物种是·O2–和h+。 相似文献
14.
以钛酸四丁酯为前驱体,硅藻土为载体,采用溶胶-凝胶法制备TiO_2/硅藻土负载型光催化剂。以硝酸镧为镧源,采用等体积浸渍-焙烧法制备La~(3+)/TiO_2硅藻土光催化剂。通过XRD和SEM对制备的催化剂进行表征,以亚甲基蓝溶液模拟有机废水,考察n(Ti)∶n(Si)及La3+掺杂量对催化剂光催化性能的影响,结果表明,硅藻土可提高TiO_2分散性,降低TiO_2晶粒尺寸,并抑制其由锐钛矿相向金红石相的转变。在n(Ti)∶n(Si)=1∶1、焙烧温度550℃和La3+掺杂质量分数1%条件下,La~(3+)/TiO_2硅藻土光催化剂的光催化活性较好,紫外光连续照射180 min,亚甲基蓝降解率可达99.9%。 相似文献
15.
Hiromi Yamashita Masaru Harada Junko Misaka Masato Takeuchi Bernaurdshaw Neppolian Masakazu Anpo 《Catalysis Today》2003,84(3-4):191-196
The application of metal ion-implantation method has been made to improve the electronic properties of the TiO2 photocatalyst to realize the utilization of visible light. The photocatalytic properties of these unique TiO2 photocatalysts for the purification of water have been investigated. By the metal ion-implantation method, metal ions (Fe+, Mn+, V+, etc.) are accelerated enough to have the high kinetic energy (150 keV) and can be implanted into the bulk of TiO2. TiO2 photocatalysts which can absorb visible light and work as a photocatalyst efficiently under visible light irradiation were successfully prepared using this advanced technique. The UV-Vis absorption spectra of these metal ion-implanted TiO2 photocatalysts were found to shift toward visible light regions depending on the amount and the kind of metal ions implanted. They were found to exhibit an effective photocatalytic reactivity for the liquid-phase degradation of 2-propanol diluted in water at 295 K under visible light (λ>450 nm) irradiation. The investigation using XAFS analysis suggested that the substitution of Ti ions in TiO2 lattice with implanted metal ions is important to modify TiO2 to be able to adsorb visible light. 相似文献
16.
Hiromi Yamashita Shinichi Kawasaki Shuai Yuan Kazuhiro Maekawa Masakazu Anpo Michio Matsumura 《Catalysis Today》2007,126(3-4):375-381
Using the F− media, the hydrophobic zeolite and mesoporous silica can be synthesized. These hydrophobic porous materials exhibit the high ability for the adsorption of organic compounds diluted in water and become the useful supports of photocatalyst. The hydrophobic Ti-Beta(F) zeolite prepared in the F− media exhibited high efficiency than the hydrophilic Ti-Beta(OH) zeolite prepared in OH− media for the liquid-phase photocatalytic degradation of 2-propanol diluted in water to produce CO2 and H2O. The TiO2 loaded on the hydrophobic mesoporous silica HMS(F) (TiO2/HMS(F)), which was synthesized using tetraethyl orthosilicate, tetraethylammonium fluoride as the source of the fluoride and dodecylamine as templates, also exhibited the efficient photocatalytic performance for the degradation. The amount of adsorption of 2-propanol and the photocatalytic reactivity for the degradation increased with increasing the content of fluoride ions on these photocatalysts. The efficient photocatalytic degradation of 2-propanol diluted in water on Ti-Beta(F) zeolite and TiO2/HMS(F) mesoporous silica can be attributed to the larger affinity for the adsorption of propanol molecules on the titanium oxide species depending on the hydrophobic surface properties of these photocatalysts. 相似文献
17.
Aqueous dispersion containing TiO2 particles was firstly prepared and then mixed with silicone or acrylic additives to establish a treating bath. And the fibrous TiO2 photocatalysts were produced by padding three woven fabrics including cotton, polyester and flax fabrics as support materials with this treating bath and some factors affecting the preparation process were discussed. Moreover, the fibrous TiO2 photocatalysts were characterized by X-ray diffractometer, infrared Fourier transform spectrometer and scanning electron microscope, and evaluated with respect to the removal efficiency of ammonia under UV irradiation in air stream by a specifically designed photocatalytic reactor and environmental condition simulated chamber. The results showed that ammonia gas could well be decomposed by the fibrous TiO2 photocatalysts based on cotton and flax fabrics. Increasing the dosage of TiO2 aqueous dispersion led to the improved ammonia decomposition level of the fibrous TiO2 photocatalysts. The additives caused the reduced ammonia decomposition level of the fibrous TiO2 photocatalysts, but provided it with the enhanced resistance to water washing. The ammonia photocatalysis of the fibrous TiO2 photocatalysts was not much affected by curing temperature and dyed cotton fabrics when preparing. 相似文献
18.
用硝酸银和钛酸正丁酯为原料,采用溶胶-凝胶-微波辐射干燥法合成银掺杂TiO_2光催化剂TiO_2-Ag。为了提高催化剂的光催化活性和降解有机污染物的速率,用微波辅助Ti O2-Ag光催化剂降解有机污染物。通过扫描电子显微镜、红外光谱法、紫外可见光谱法和荧光光谱法对TiO_2-Ag催化剂进行测试和表征。以甲基橙为有机污染物,分别在太阳光照射和微波、紫外、紫外-微波条件下降解甲基橙以考察催化剂的光催化活性。结果表明,TiO_2-Ag光催化剂最佳制备条件为:银掺杂量n(Ag+)∶n(Ti~(4+))=0.003,离子液体用量3.0 m L,微波干燥功率210 W,微波干燥时间20 min,焙烧温度650℃,焙烧时间3 h,此条件下制备的TiO_2-Ag光催化剂在太阳光照射4 h下,紫外光照、微波辐射和紫外光照-微波辐射分别辐射55 min后,甲基橙降解率分别为98.70%、98.79%和99.05%。 相似文献
19.
20.
N. Bouazza M.A. Lillo-Rdenas A. Linares-Solano 《Applied catalysis. B, Environmental》2008,77(3-4):284-293
In a previous study we have shown that the pelletization of titanium dioxide, a convenient step for gas phase applications, causes an important activity lost. Such activity lost can be partially recovered pelletizing in presence of carbon materials. Porosity, as well as carbon conductivity of the selected carbon material, is important. Based on these previous results, we analyze the pelletization of TiO2 in presence of “white additives”, such as MCM-41, zeolites, metal–organic framework, SiO2, Al2O3, glass wool and quartz wool. Our results show that the activities of these composite photocatalytic pellets are higher than that of 100% TiO2-pellets. Pellets containing MCM-41, precipitated SiO2, glass wool and quartz wool present the highest propene conversions. Attention has been paid to the effect of porosity and UV-absorbance on the resulting photocatalytic activity. Although it is difficult to find a correlation between the porosity of these “white additives” and the photocatalytic activity of the TiO2-based materials, additives with no porosity or with some mesoporous contribution seem to be desired to maximize the activity. The different catalytic activities for the studied photocatalysts could not be explained on basis of their UV-absorption and further research is currently being performed trying to deep into the reasons for such behaviour. Comparison of the photocatalytic activities for pellets containing the above-mentioned “white additives” with those of a TiO2/carbon photocatalyst having the highest porosity and conductivity among all those studied highlights the superior performance of the samples containing “white additives”. 相似文献