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1.
Khadijeh Beigom Ghoreishi Nilofar Asim Zatil Amali Che Ramli Zeynab Emdadi M. Ambar Yarmo 《Journal of Porous Materials》2016,23(3):629-637
Recent improvements in the performance of photocatalysts made it possible to tackle pollution through environment friendly methods. This study investigates the modification of the photocatalytic activity of TiO2 by employing WO3 and conductive polymers, namely, polyaniline (Pani) and polypyrrole (Ppy). Basing on our previous improvement of TiO2 using a conductive polymer and activated carbon (AC), this study determines the activated carbon forms of TiO2. The prepared composites are characterized using X-ray powder diffraction, transmission electron microscopy, Fourier transform infrared, thermogravimetric analysis, Brunauer–Emmet–Teller, and UV–Vis spectroscopy. The specific surface area of the mesoporous composites is as follows: WO3/TiO2·AC (Pani) > WO3/TiO2·AC (Ppy) > WO3/TiO2·Pani > WO3/TiO2·Ppy (127 > 98 > 68 > 44 m2 g?1), which exhibited a similar trend to the photocatalytic performances (100 > 95 > 91 > 72 % conversion rate). This result could be attributed to higher porosity, surge of charge separation, and photo-responding range extension induced by the synergistic effect of WO3, conducting polymers, and TiO2 in the samples. 相似文献
2.
As a new type of photoelectrode, TiO2/Ni thin-film electrode was prepared by dip-coating technique. The structural and surface morphology of electrode was examined
by X-ray diffraction (XRD) and scanning electron microscope (SEM). Effects of initial phenol concentration, pH value, number
of film layers, voltage of electrical bias applied, variation of inorganic salt type and types of dissolved gas on the photoelectrocatalytic
(PEC) degradation of phenol using ultraviolet (UV) illuminated TiO2/Ni thin-film electrode were investigated. The mechanism of PEC degradation of phenol was also studied by analyzing reaction
intermediates. 相似文献
3.
TiO2-Al2O3 mixed oxides with different compositions ranging from 40wt-% to 95wt-% of TiO2 were prepared by sol-gel method and impregnated with different amounts of VO x . Supports and catalysts were characterized by X-ray diffraction (XRD), physisorption, temperature preprogrammed reduction (H2-TPR), and ammonia temperature programmed desorption (NH3-TPD). TiO2 content in the support had obvious effect on the crystal structure, texture characteristic, acid property, and catalytic activity in dehydrogenation of ethylbenzene (EB) with carbon dioxide. The highest catalytic activity was acquired when the TiO2 content was 50 wt-%. 相似文献
4.
Mi Ran Lee Myung-June Park Wonjin Jeon Jae-Wook Choi Young-Woong Suh Dong Jin Suh 《Korean Journal of Chemical Engineering》2011,28(11):2142-2147
Reactor modeling for the oxidative coupling of methane over Na2WO4/Mn/SiO2 catalyst was addressed in the present study. The catalyst loading part was designed to be thicker than the inlet and outlet
parts to reduce the rates of side reactions in the gas phase, and the optimal aspect ratio (L to D ratio) for no pressure
drop and minimum side reactions was determined in experimental studies. Experiments were also conducted under a variety of
operating conditions such as gas hourly space velocity (GHSV), CH4/O2 ratio and reaction temperature, and partial least-squares model was applied to predict the performance of the reactor. The
validity of the developed model was corroborated by the comparison with experimental data, and normalized parametric sensitivity
analysis was carried out. Finally, the genetic algorithm (GA) was applied to determine the optimal conditions for maximum
production of ethane and ethylene. 相似文献
5.
Nattapong Kasempremchit Piyasan Praserthdam Suttichai Assabumrungrat 《Korean Journal of Chemical Engineering》2016,33(10):2842-2848
We examined the catalyst bed design of MgO and WO3/SiO2 for production of propylene via metathesis of 1-butene. WO3/SiO2 was used as a bi-functional catalyst for isomerization and metathesis reactions. Addition of MgO was proposed to help improve the isomerization activity and hence the propylene yield. Experimental studies were carried out to determine activity and reaction kinetics of 1-butene isomerization over MgO isomerization catalyst and 1-butene metathesis over WO3/SiO2 bi-functional catalyst for designing a suitable catalyst bed. Two types of catalyst bed arrangement—physically mixed bed and separated bed—were considered and compared by computer simulation. The simulations reveal that adding MgO in the separated bed by packing MgO before WO3/SiO2 offers superior propylene yield to the physically mixed bed. The appropriate %MgO loading in catalyst bed which offers a maximum propylene yield was found to vary (3 and 23%), depending on operating condition. 相似文献
6.
Zhixiong Zhou Lihua Zhu Jing Li Heqing Tang 《Journal of Applied Electrochemistry》2009,39(10):1745-1753
Uniform TiO2/SiO2 composite films were prepared on ITO substrates by electrodeposition, and highly photoelectrocatalytic (PEC) activity of
the composite films was observed toward the degradation of methyl orange (MO) in aqueous solutions. It was further found that
their PEC activity was dependent on the electrodeposition parameters including deposition time, solution pH and SiO2 content. Under the optimized condition, the PEC degradation of MO on TiO2/SiO2 composite film electrode could be enhanced about 14 times relative to that on neat TiO2 film electrode. The high PEC activity of the TiO2/SiO2 composite film electrode was mainly attributed to the enhancement of the charge separation of photo-generated electron-hole
pairs by the dispersion of SiO2 nanoparticles in the TiO2 matrix with the aid of the applied electric field. 相似文献
7.
N. V. Lebukhova V. S. Rudnev P. G. Chigrin K. S. Makarevich I. B. Lukiyanchuk N. F. Karpovich 《Catalysis in Industry》2011,3(3):294-300
Two methods were used to obtain a catalytically active oxide coating on the surface of titanium for the catalytic afterburning
of diesel soot: plasma electrochemical formation of an oxide film on the surface of titanium and extraction pyrolytic deposition
of the Li2Cu2(MoO4)3 compound. The Li2Cu2(MoO4)3/TiO2 + SiO2/Ti compositions synthesized by the single-step extraction pyrolytic treatment of the oxidized surface of titanium ensured
a high burning rate of soot of ∼300°C. The subsequent deposition of Li2Cu2(MoO4)3 lowers the activity of the catalyst, due probably to the growth of molybdate phase crystallites and the filling of open oxide
film pores. Double lithium-copper molybdate is able to reduce appreciably the concentration of CO in the oxidation products
of soot. The advantages of these methods are the possibility of forming high-cohesion durable coatings on surfaces of any
complexity, the simplicity of their implementation, and high productivity and low cost. The obtained results can be recommended
for use in developing methods for creating composite coatings on catalytic soot filters. 相似文献
8.
Wei Peng Jie Liu Chenxu Li Fuxing Zong Wensi Xu Xing Zhang Zhendong Fang 《Korean Journal of Chemical Engineering》2018,35(8):1662-1672
Heterogeneous catalysts with low cost, environmentally friendly, highly effective and ready separation from aqueous solution are highly desirable. Magnetic CuO-Fe3O4 nanoparticles, a type of non-toxic bimetallic transition metal oxide, is a promising heterogeneous catalyst for activation of peroxymonosulfate (PMS) to generate reactive oxygen species (ROS) that has not been previously investigated. In this study, the activation of PMS by CuO-Fe3O4 nanoparticles was evaluated using the degradation of 4-chlorophenol as a model reaction. Several critical factors such as pH, catalyst dosage and PMS concentration were investigated. CuO-Fe3O4/PMS system demonstrated a wide effective pH range to degrade 4-chlorophenol, namely 5.5 to 9.5. With the increase of the catalyst dosage, the degradation efficiency of 4-chlorophenol appeared to increase first and then decrease, that the inflection point was 0.5 g/L. Elevated PMS concentration obviously improved the decomposition of 4-chlorophenol; however, the plateau was reached when the PMS concentration was 8 mM. Further increase in PMS concentration would not significantly improve the removal efficiency. Through examining the effects of scavengers and electron spin resonance (ESR) analyses, CuO-Fe3O4 nanoparticles were proven to activate PMS through a non-radical and radical pathway to generate singlet oxygen, sulfate radicals and hydroxyl radicals. Based on results, CuO-Fe3O4 nanoparticles were effective, environmentally friendly and low cost catalysts for efficient activation of PMS. These features make CuO-Fe3O4 nanoparticles a readily available heterogeneous catalyst to activate PMS for refractory organic pollutants degradation in advanced oxidation processes (AOPs). 相似文献
9.
Philomena Schlexer Hsin-Yi Tiffany Chen Gianfranco Pacchioni 《Catalysis Letters》2017,147(8):1871-1881
10.
Vanadium oxide supported on zirconia modified with WO3 was prepared by adding Zr(OH)4 powder into a mixed aqueous solution of ammonium metavanadate and ammonium metatungstate followed by drying and calcining
at high temperatures. The characterization of prepared catalysts was performed by using FTIR, Raman, and XRD. In the case
of calcination temperature at 773 K, for samples containing low loading V2O5 below 18 wt%, vanadium oxide was in a highly dispersed state, while for samples containing high loading V2O5 equal to or above 18 wt%, vanadium oxide was well crystallized due to the high V2O5 loading on the surface of ZrO2. The ZrV2O7 compound was formed through the reaction of V2O5 and ZrO2 at 873 K, and the compound decomposed into V2O5 and ZrO2 at 1,073 K, these results were confirmed by FTIR and XRD. Catalytic tests for 2-propanol dehydration and cumene dealkylation
have shown that the addition of WO3 to V2O5/ZrO2 enhanced both catalytic activity and acidity of V2O5-WO3/ZrO2 catalysts. The variations in catalytic activities for both reactions are roughly correlated with the changes of acidity. 相似文献
11.
Zhi-Yuan Yang Guang-Yu Shen Yun-Peng He Xiao-Xia Liu Shui-Jin Yang 《Journal of Porous Materials》2016,23(3):589-599
The composite semiconductor photocatalyst TiO2/SiO2 was prepared by template-hydrothermal method using carbon spheres as the template. The structural and optical properties of TiO2/SiO2 were characterized by XRD, SEM, BET, UV–Vis DRS, TG-DTA, PL techniques. The formation of hydroxyl radical on the surface of TiO2/SiO2 was studied with terephthalic acid as the probe molecule, combined with fluorescence technique. The results showed that the specific surface area of TiO2/SiO2 composite was 327.9 m2/g, and the specific surface area of TiO2/SiO2 was larger than that of pure TiO2. Photocatalytic degradation of rhodamine B showed that TiO2/SiO2 composite oxide under visible light illumination 40 min, the degradation rate was 98.6 % and the degradation rate of pure TiO2 was only 11.9 %. The apparent first-order rate constant of TiO2/SiO2 was 33 times that of pure TiO2 and more than 6 times that of P25 when the molar ratio of Ti to Si was 1:1 under visible light irradiation. Moreover, it’s also as much as 5 times that of pure TiO2 and is more than 1 times that of P25 under UV light irradiation 25 min. Based on the experimental results, ·O2 ? and h+ were suggested to be the major active species which was responsible for the degradation reaction. The increased photocatalytic activity of TiO2/SiO2 may be mainly attributed to effectively suppressing the recombination of hole/electron pairs. After the photocatalyst TiO2/SiO2 was reused 5 times, the degradation rate of rhodamine B could reach 89.2 % under visible light irradiation. Moreover, The composite semiconductor photocatalyst TiO2/SiO2 was selective towards the degradation of rhodamine B. 相似文献
12.
Inhak Song Seunghee Youn Hwangho Lee Do Heui Kim 《Korean Journal of Chemical Engineering》2016,33(9):2547-2554
A mechanical mixture of CeO2 and TiO2 powder with a small amount of sulfate was applied for the selective catalytic reduction (SCR) of NO with NH3. After calcination at 500 oC, the mixed sample showed significantly enhanced activity and selectivity compared to the uncalcined one and, moreover, demonstrated even higher activity than the conventional V2O5/TiO2 catalyst above 300 °C. Combined characterization results revealed that the main active sites were newly formed sulfate species on CeO2, the number of which increased with calcination. Temperatureresolved DRIFT spectra provided convincing evidence about the migration of sulfate species from TiO2 to CeO2, as confirmed from the shift of v(S=O) band as a result of the mechanical mixing and the subsequent calcination. 相似文献
13.
Chuanmin Chen Wenbo Jia Songtao Liu Yue Cao Bing Zhao Jianqiao Wang 《Korean Journal of Chemical Engineering》2018,35(3):637-644
CuCl2-SCR catalysts prepared by an improved impregnation method were studied to evaluate the catalytic performance for gaseous elemental mercury (Hg0) oxidation in simulated flue gas. Hg0 oxidation activity of commercial SCR catalyst was significantly improved by the introduction of CuCl2. Nitrogen adsorption, XRD, XRF and XPS were used to characterize the catalysts. The results indicated that CuCl2 was well loaded and highly dispersed on the catalyst surface, and that CuCl2 played an important role for Hg0 catalytic oxidation. The effects of individual flue gas components on Hg0 oxidation were also investigated over CuCl2-SCR catalyst at 350 oC. The co-presence of NO and NH3 remarkably inhibited Hg0 oxidation, while this inhibiting effect was gradually scavenged with the decrease of GHSV. Further study revealed the possibility of simultaneous removal of Hg0 and NO over CuCl2-SCR catalyst in simulated flue gas. The mechanism of Hg0 oxidation was also investigated. 相似文献
14.
Wathanyoo Owpradit Okorn Mekasuwandumrong Joongjai Panpranot Artiwan Shotipruk Bunjerd Jongsomjit 《Polymer Bulletin》2011,66(4):479-490
This article reveals the dependence of crystalline phases in titania on the intrinsic activity during in situ polymerization
of ethylene/1-hexene using the zirconocene/dMMAO catalyst to produce LLDPE/TiO2 nanocomposites. First, the TiO2 nanoparticles having different crystalline phases were employed as the nanofillers by impregnation with dMMAO to obtain dMMAO/TiO2. Then, copolymerization of ethylene/1-hexene using zirconocene catalyst was performed in the presence of dMMAO/TiO2. It was found that the catalytic activity derived from the anatase TiO2 (A) was about four times higher than that obtained from the rutile TiO2 (R). This was likely due to higher intrinsic activity of the active species present on the TiO2 (A). In addition, increased [Al]dMMAO/[Zr]cat ratios apparently resulted in enhanced activities for both TiO2 (A) and TiO2 (R). However, the TiO2 (R) showed less deactivation upon increased [Al]dMMAO/[Zr]cat ratios. This can be attributed to strong interaction between dMMAO and TiO2 (R) as proven by the TGA measurement. The microstructure of the LLDPE/TiO2 obtained was found to be random copolymer for both TiO2 (A) and TiO2 (R). 相似文献
15.
16.
Mouza Al Ruqaishy Faisal Al Marzouqi Kezhen Qi Shu-yuan Liu Sreejith Karthikeyan Younghun Kim Salma Mohamed Zahran Al-Kindy Alex Tawanda Kuvarega Rengaraj Selvaraj 《Korean Journal of Chemical Engineering》2018,35(11):2283-2289
TiO2 microspheres were successfully synthesised by simple solution phase method by using various amount of titanium butoxide as precursor. The prepared TiO2 were characterized by X-ray diffraction (XRD), UV-vis diffuse reflectance absorption spectra (UV-DRS), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). XRD analysis revealed that the as-synthesized TiO2 microsphere poses an anatase phase. The photocatalytic degradation experiments were carried out with three different dyes, such as methylene blue, brilliant black, reactive red-120 for four hours under UV light irradiation. The results show that TiO2 morphology had great influence on photocatalytic degradation of organic dyes. The experimental results of dye mineralization indicated the concentration was reduced by a high portion of up to 99% within 4 hours. On the basis of various characterization of the photocatalysts, the reactions involved to explain the photocatalytic activity enhancement due to the concentration of titanium butoxide and morphology include a better separation of photogenerated charge carriers and improved oxygen reduction inducing a higher extent of degradation of aromatics. 相似文献
17.
Lixin Zhang Chunmei Xie Hongfang Jiu Yajuan Meng Qing Zhang Yuying Gao 《Catalysis Letters》2018,148(9):2812-2821
The hollow TiO2@g-C3N4 composites were synthesized by a facile stirring method. The phase compositions, optical properties, and morphologies of the samples were characterized via X-ray diffraction, scanning electron microscope, transmission electron microscopy, high resolution transmission electron microscopy, fourier transform infrared spectroscopy, N2 adsorption–desorption, UV–Vis diffuse reflectance spectroscopy and Photoluminescence. The photocatalyitc performance was evaluated by reduction carbon dioxide under visible light irradiation. The results indicated that TiO2@g-C3N4 nanocomposites displayed higher photocatalytic activity compared with pure g-C3N4. The increased photocatalytic activity of TiO2@g-C3N4 nanocomposites can be attributed to facilitating the photo-induced electron–hole separation efficiency and enhancing the photo-induced electron migration. 相似文献
Graphical Abstract
18.
PSA [poly-(styrene-methyl acrylic acid)] latex particle has been taken into account as template material in SiO2 hollow spheres preparation. TiO2-doped SiO2 hollow spheres were obtained by using the appropriate amount of Ti(SO4)2 solution on SiO2 hollow spheres. The photodecomposition of the MB (methylene blue) was evaluated on these TiO2-doped SiO2 hollow spheres under UV light irradiation. The catalyst samples were characterized by XRD, UV-DRS, SEM and BET. A TiO2-doped SiO2 hollow sphere has shown higher surface area in comparison with pure TiO2 hollow spheres. The 40 wt% TiO2-doped SiO2 hollow sphere has been found as the most active catalyst compared with the others in the process of photodecomposition of
MB (methylene blue). The BET surface area of this sample was found to be 377.6 m2g−1. The photodegradation rate of MB using the TiO2-doped SiO2 catalyst was much higher than that of pure TiO2 hollow spheres. 相似文献
19.
Simona Ostachaviciute Jonas Baltrušaitis Eugenijus Valatka 《Journal of Applied Electrochemistry》2010,40(7):1337-1347
Thin films of bare and Se-containing tungsten trioxide (WO3) on AISI304-type stainless steel were prepared by electrochemical deposition using peroxy-tungstate solutions. The obtained
films were characterized by X-ray diffraction, photoelectron spectroscopy, scanning electron microscopy, thermal and photovoltammetry
analyses. The oxidation of methylene blue, phenol, and methanol was used to evaluate the photoelectrocatalytic activity of
the prepared films. It has been established that the incident photon-to-current efficiency (IPCE) in 0.1-M K2SO4 decreases as the concentration of methylene blue and phenol increases. On the contrary, the IPCE values increase with the
increase in initial concentration of methanol. The bulk electrolysis experiments revealed that the prepared films are stable
and can be used for photoelectrochemical oxidation of methanol. 相似文献
20.
Maamar Fedailaine Sabrina Berkani Mohamed Trari 《Korean Journal of Chemical Engineering》2016,33(7):2027-2033
The photo-electrochemical characterization of the hetero-system CoFe2O4/TiO2 was undertaken for the Ni2+ reduction under solar light. The spinel CoFe2O4 was prepared by nitrate route at 940 °C and the optical gap (1.66 eV) was well matched to the sun spectrum. The flat band potential (-0.21 VSCE) is more cathodic than the potential of Ni2+/Ni couple (-0.6 VSCE), thus leading to a feasible nickel photoreduction. TiO2 with a gap of 3.2 eV is used to mediate the electrons transfer. The reaction is achieved in batch configuration and is optimized with respect to Ni2+ concentration (30 ppm); a reduction percentage of 72% is obtained under sunlight, the Ni2+ reduction is strongly enhanced and follows a first order kinetic with a rate constant of 4.6×10-2 min-1 according to the Langmuir-Hinshelwood model. 相似文献