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1.
Catalytic efficiency, stability and environmental applicability of five iron(III) oxide nanopowders differing in surface area and crystallinity were tested in degradation of concentrated phenolic aqueous solutions (100 g/L) at mild temperature (30 °C), initially almost neutral pH and equimolar ratio of hydrogen peroxide and phenol. The catalyst properties were easily controlled by varying in reaction time during isothermal treatment of ferrous oxalate dihydrate in air at 175 °C. Although the catalytic efficiency clearly increases with the surface area of the nanopowders, it is not due to the solely heterogeneous catalytic mechanism as would be expected. The amorphous Fe2O3 nanopowders possessing the largest surface areas (401 m2 g−1, 386 m2 g−1) are the most efficient catalysts evidently due to their highest susceptibility to leaching in acidic environment arising as a consequence of phenol degradation products. Thus, these amorphous samples act partially as homogeneous catalysts, which was confirmed by a high concentration of leached Fe(III) ions in the solution (19 ppm). The crystalline hematite (α-Fe2O3) samples, varying in surface area between 337 m2 g−1 and 245 m2 g−1, are generally less efficient when compared to the amorphous powders, however their catalytic action is almost exclusively heterogeneous as only 3 ppm of leached Fe(III) was found in the reaction systems catalyzed by nanohematite samples. A significant difference in relative contributions of heterogeneous and homogenous catalysis was definitely established in buffered reaction systems catalyzed by amorphous Fe2O3 and nanocrystalline hematite. The nanohematite sample exhibiting the highest heterogeneous action was tested at decreased initial phenol concentration (10 g/L), which is closer to the real contents of phenol in waste waters, and at different hydrogen peroxide/phenol molar ratios to consider its environmental applicability. At the hydrogen peroxide/phenol ratio equal to 5, no traces of the leached iron were detected and the phenol conversion of 84% was reached. Moreover, such a high degree of conversion is accompanied by a decrease of the chemical oxygen demand (COD) from the initial value of 11.23 g/L to 4.22 g/L after 125 min. This fact indicates that the considerable fraction of primary reaction products was totally degraded. 相似文献
2.
Morphology-dependent redox and catalytic properties of CeO2 nanostructures: Nanowires, nanorods and nanoparticles 总被引:1,自引:0,他引:1
The redox features and the catalytic activities of ceria nanowires, nanorods and nanoparticles were comparatively studied. The morphology-dependent phenomenon is closely related to the nature of the exposed crystal planes. The CeO2 nanoparticles mainly expose the stable {1 1 1} plane on the surface, whereas the rod-shaped nanostructures preferentially expose the reactive {1 1 0} and {1 0 0} planes, giving higher oxygen storage capacity and catalytic activity for CO oxidation. Although both the CeO2 nanorods and the CeO2 nanowires predominantly expose the reactive {1 1 0} and {1 0 0} planes, the CeO2 nanowires favor to expose a large proportion of active planes on the surface, resulting in a much higher activity for CO oxidation than the nanorods. 相似文献
3.
Nitikon Wongwaranon Okorn Mekasuwandumrong Piyasan Praserthdam Joongjai Panpranot 《Catalysis Today》2008,131(1-4):553
Nanocrystalline α-Al2O3 and Ni-modified α-Al2O3 have been prepared by sol–gel and solvothermal methods and employed as supports for Pd catalysts. Regardless of the preparation method used, NiAl2O4 spinel was formed on the Ni-modified α-Al2O3 after calcination at 1150 °C. However, an addition of NiO peaks was also observed by X-ray diffraction for the solvothermal-made Ni-modified α-Al2O3 powder. Catalytic performances of the Pd catalysts supported on these nanocrystalline α-Al2O3 and Ni-modified α-Al2O3 in selective hydrogenation of acetylene were found to be superior to those of the commercial α-Al2O3 supported one. Ethylene selectivities were improved in the order: Pd/Ni-modified α-Al2O3–sol–gel > Pd/Ni-modified α-Al2O3-solvothermal ≈ Pd/α-Al2O3–sol–gel > Pd/α-Al2O3-solvothermal Pd/α-Al2O3-commerical. As revealed by NH3 temperature program desorption studies, incorporation of Ni atoms in α-Al2O3 resulted in a significant decrease of acid sites on the alumina supports. Moreover, XPS revealed a shift of Pd 3d binding energy for Pd catalyst supported on Ni-modified α-Al2O3–sol–gel where only NiAl2O4 was formed, suggesting that the electronic properties of Pd may be modified. 相似文献
4.
Domna A. Constantinou Jos Luis G. Fierro Angelos M. Efstathiou 《Applied catalysis. B, Environmental》2009,90(3-4):347-359
The steam reforming of phenol towards H2 production was studied in the 650–800 °C range over a natural pre-calcined (air, 850 °C) calcite material. The effects of reaction temperature, water, hydrogen, and carbon dioxide feed concentrations, and gas hourly space velocity (GHSV, h−1) were investigated. The increase of reaction temperature in the 650–800 °C range and water feed concentration in the 40–50 vol% range were found to be beneficial for catalyst activity and H2-yield. A similar result was also obtained in the case of decreasing the GHSV from 85,000 to 30,000 h−1. The effect of concentration of carbon dioxide and hydrogen in the phenol/water feed stream was found to significantly decrease the rate of phenol steam reforming reaction. The latter was probed to be related to the reduction in the rate of water dissociation as evidenced by the significant decrease in the concentration of adsorbed bicarbonate and OH species on the surface of CaO according to in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS)-CO2 adsorption experiments in the presence of water and hydrogen in the feed stream. Details of the CO2 adsorption on the CaO surface at different reaction temperatures and gas atmospheres using in situ DRIFTS and transient isothermal adsorption experiments with mass spectrometry were obtained. Bridged, bicarbonate and unidentate carbonate species were formed under CO2/H2O/He gas mixtures at 600 °C with the latter being the most populated. A substantial decrease in the surface concentration of bicarbonate and OH species was observed when the CaO surface was exposed to CO2/H2O/H2/He gas mixtures at 600 °C, result that probes for the inhibiting effect of H2 on the phenol steam reforming activity. Phenol steam reforming reaction followed by isothermal oxygen titration allowed the measurement of accumulated “carbonaceous” species formed during phenol steam reforming as a function of reaction temperature and short time on stream. An increase in the amount of “carbonaceous” species with reaction time (650–800 °C range) was evidenced, in particular at 800 °C (4.7 vs. 6.7 mg C/g solid after 5 and 20 min on stream, respectively). 相似文献
5.
Hui Dong Zhaohui Li Ximing Xu Zhengxin Ding Ling Wu Xuxu Wang Xianzhi Fu 《Applied catalysis. B, Environmental》2009,89(3-4):551-556
Delafossite-structured oxides AgMO2 (M = Al, Ga, In) were successfully synthesized using fluoro(ethylene-propylene) (FEP) pouch via a facile hydrothermal method. The obtained samples were characterized by X-ray diffraction (XRD), BET surface area measurement, UV–vis diffuse reflectance spectroscopy (DRS), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The photocatalytic activity of the as-prepared samples was evaluated by the degradation of rhodamine B (RhB) and methyl orange (MO) under visible light irradiation. All three samples showed photocatalytic activity for RhB and MO degradation under visible light irradiations and their photocatalytic activity followed the order of AgInO2 > AgGaO2 > AgAlO2. The relative high photocatalytic activity of AgInO2 can be attributed to its high quantity of the surface hydroxyl groups. The photocatalytic mechanism of AgInO2 was proposed and its stability was also investigated. 相似文献
6.
Iron oxide and TiO2 were immobilized on modified polyvinyl fluoride films in a sequential process. Synergic effects of iron oxide and TiO2 on the polymer film were observed during the heterogeneous degradation of hydroquinone (HQ) in the presence of H2O2 at pH close to neutrality and under simulated solar irradiation. Within the degradation period, little iron leaching (<0.5 mg/L) was observed.The surface of commercial polyvinyl fluoride (PVF) film was modified by TiO2 under light inducing oxygen group (C–OH, CO, COOH) formation on the film surface. During this treatment, TiO2 nanoparticles simultaneously bind to the film, leading to PVFf–TiO2. The possible mechanistic pathway for the TiO2 deposition and the nature of the polymer–TiO2 interaction are discussed. Furthermore PVF and PVFf–TiO2 were immersed in an aqueous solution for the deposition of iron oxide layer by hydrolysis of FeCl3, leading to PVF–Fe oxide and to PVFf–TiO2–Fe oxide respectively.HQ degradation and mineralization mediated by PVFf–TiO2, PVF–Fe oxide and PVFf–TiO2–Fe oxide were investigated under different conditions. Remarkable synergistic effects were observed for PVFf–TiO2–Fe oxide possibly due to Fe(II) regeneration, accelerated by electron transfer from TiO2 to the iron oxide under light. 相似文献
7.
Satoshi Horikoshi Takashi Miura Masatsugu Kajitani Natsuko Horikoshi Nick Serpone 《Applied catalysis. B, Environmental》2008,84(3-4):797-802
The photoassisted degradation (HPLC-UV absorption), dehalogenation (HPLC-IC) and mineralization (TOC decay) of the flame retardants tetrabromobisphenol-A (TBBPA) and tetrachlorobisphenol-A (TCBPA) were examined in UV-irradiated alkaline aqueous TiO2 dispersions (pH 12), and for comparison the parent bisphenol-A (BPA, an endocrine disruptor) in pH 4–12 aqueous media to assess which factor impact most on the photodegradative process. Complete degradation (2.7–2.8 × 10−2 min−1) and dehalogenation (1.8 × 10−2 min−1) of TBBPA and TCBPA occurred within 2 h of UV irradiation, whereas only 45–60% mineralization (2.3–2.7 × 10−3 min−1) was complete within 5 h for the flame retardants at pH 12 and ca. 80% for the parent BPA. Factors examined in the pH range 4–12 that impact the degradation of BPA were the point of zero charge of TiO2 particles (pHpzc; electrophoretic method), particle or aggregate sizes of TiO2 (light scattering), and the relative number of OH radicals (as DMPO–OH adducts; ESR spectroscopy) produced in the UV-irradiated dispersion. Dynamics of BPA degradation (2.0–2.4 × 10−2 min−1) were pH-independent and independent of particle/aggregate size, but did correlate with the number of OH radicals, at least at pHs 4 to 8–9, after which the rates decreased somewhat at pH > 9 with decreasing adsorption owing to Coulombic repulsive forces between the very negative TiO2 surface and the anionic forms of BPA (pKas ca. 9.6–11.3), even though the number of OH radicals continued to increase at the higher pHs. 相似文献
8.
Impact of supercritical drying and heat treatment on physical properties of titania/silica aerogel monolithic and its applications 总被引:1,自引:0,他引:1
TiO2–SiO2 monolithic aerogels were homogeneously prepared using sol–gel method. Critical point of drying of TiO2–SiO2 gels with ethanol was studied for 30, 60, 90 and 120 min. Subsequently, the gels were dried with supercritical ethanol, resulting in amorphous aerogels that crystallized following heat treatment at 550 °C from 1 to 5 h. The TiO2–SiO2 aerogels were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and surface area measurements. The molar ratio of SiO2:TiO2 was 6 and the synthetic strategy revealed that TiO2–SiO2 aerogel, had a surface area 868 m2/g, particle size 40 nm, density 0.17 g/cm3 and 80% porosity. The finding indicated that from economic point of view, TiO2–SiO2 gel should be supercritical dried for 30 min and heat-treated for 5 h. The TiO2–SiO2 aerogel monoliths photocatalyst synthesized using sol–gel method provided insight into the characteristics that make a photocatalyst material well-suited for photodegradation of phenol and cyanide in an industrial waste stream containing Cl−, S2− and NH4+. Interestingly, after multiple reuse cycles (i.e. ≥7), photodegradation systems with regenerated photocatalyst showed a slightly decreasing of photoactivity 2–4%. The overall kinetics of photodegradation of either phenol or cyanide using TiO2–SiO2 aerogel photocatalyst was found to be of first order. 相似文献
9.
CeO2–TiO2 (Ce:Ti = 0.25–9, molar ratio) catalysts were synthesized by a sol–gel method and the catalytic performances were evaluated in the selective synthesis of isobutene and isobutane from CO hydrogenation under the reaction conditions of 673–748 K, 1–5 MPa and 720–3000 h−1. The physical properties, such as specific surface area, cumulative pore volume, average pore diameter, crystal phase and size, of the catalysts were characterized by N2 adsorption/desorption and XRD. All the CeO2–TiO2 composite oxides showed higher surface areas than pure TiO2 and CeO2. No TiO2 phase was detected on the samples of CeO2–TiO2 in which TiO2 contents were in the range of 10–50 mol%. Crystalline Ce2O3 was detected in CeO2–TiO2 (8:2). The reaction conditions, temperature, pressure and space velocity, had obvious influences on the CO conversion and distribution of the products over CeO2–TiO2 (8:2) catalyst. 相似文献
10.
Chaoying Ni Xiazhang Li Zhigang Chen Hui-Yin Harry Li Xinqiao Jia Ismat Shah John Q. Xiao 《Microporous and mesoporous materials》2008,115(3):247-252
Mesoporous CeO2 particles are synthesized using a sol–gel method involving Pluronic P123 or F127 tri-block copolymer and cerium acetate hydrate. Transmission electron microscopy reveals well defined meso-channels of about 10 nm in diameter and a wall framework consisting of highly oriented polycrystalline CeO2. The [0 0 1] axis of the crystals is found to be aligned parallel to the meso-channels, and lattice coherency of [1 0 0] or [0 1 0] also exists in perpendicular plane to the channel. A cooperative self-assembly of the tri-block copolymer and Ce4+ species is believed to occur, along with the precipitation of nano-crystalline CeO2 in the sol–gel process. It is proposed that the preferential orientation may result from a favored linkage of the low-order Miller indices {0 0 1} planes of CeO2 to the PEO segment in the PEO–PPO–PEO tri-block copolymer micelles. The unique structural characteristics of meso-CeO2 appear to contribute to maintaining the pore integrity during the synthesis as well as in a post-fabrication in situ TEM heating test. 相似文献
11.
A. Naydenov P. Konova Pen. Nikolov F. Klingstedt N. Kumar D. Kovacheva P. Stefanov R. Stoyanova D. Mehandjiev 《Catalysis Today》2008,137(2-4):471
A silica-supported Ag system made by the incipient wetness impregnation method was investigated in the reaction of heterogeneous catalytic decomposition of ozone. It was established that the catalytic ozone decomposition on Ag/SiO2 proceeded in the temperature interval −40 °C to 25 °C as a first order reaction with activation energy of 65 kJ/mol (pre-exponential factor 5.0 × 1014 s−1). Based on the results from the instrumental methods (SEM, XRD, XPS, EPR, TPD) it can be concluded that in presence of ozone the silver is oxidized to a complicated mixture of Ag2O3 and AgO. Due to the high activity and stability of the Ag/SiO2 catalyst, it is promising for neutralization of waste gases containing ozone. 相似文献
12.
Valerio Choque Narcís Homs Renata Cicha-Szot Pilar Ramírez de la Piscina 《Catalysis Today》2009,142(3-4):308
Ru-based catalysts supported on Ta2O5–ZrO2 and Nb2O5–ZrO2 are studied in the partial oxidation of methane at 673–873 K. Supports with different Ta2O5 or Nb2O5 content were prepared by a sol–gel method, and RuCl3 and RuNO(NO3)3 were used as precursors to prepare the catalysts (ca. 2 wt.% Ru). At 673 K high selectivity to CO2 was found. An increase of temperature up to 773 K produced an increase in the selectivity to syngas (H2/CO = 2.2–3.1), and this is related with the transformation of RuO2 to metallic Ru as was determined from XRD and XPS results. At 873 K and with co-fed CO2 an increase of the catalytic activity and CO selectivity was found. A TOF value of 5.7 s−1 and H2/CO ratio ca. 1 was achieved over Ru(Cl)/6TaZr. Catalytic results are discussed as a function of the support composition and characteristics of Ru-based phases. 相似文献
13.
G.H. Yue X. Wang L.S. Wang P. Chang R.T. Wen Y.Z. Chen D.L. Peng 《Electrochimica acta》2009,54(26):6543-6547
Fe1−xCox nanowires in self-assembled arrays with varying compositions were produced by the template-assisted pulsed electrochemical deposition method. The structural and magnetic properties of the arrays were investigated using several experimental techniques. TEM analyses indicated that the nanowires were regular, uniform, 8 μm in length and 50 nm in diameter. The results of X-ray diffraction indicated that the body-centered-cubic (bcc) (α), face-centered-cubic (fcc) (γ), and hexagonal-close-packed (hcp) () Fe–Co phases appeared in different compositions. Magnetic measurements showed that the coercivity and squareness of the hysteresis loops of the Fe1−xCox changed with their compositions, which may be attributable to shape anisotropy. The room temperature 57Fe Mössbauer spectra of the arrays of the Fe1−xCox nanowires revealed strong shape anisotropy. 相似文献
14.
Xue-Lian Liang Xin Dong Guo-Dong Lin Hong-Bin Zhang 《Applied catalysis. B, Environmental》2009,88(3-4):315-322
A type of Pd–ZnO catalysts supported on multi-walled carbon nanotubes (MWCNTs) were developed, with excellent performance for CO2 hydrogenation to methanol. Under reaction conditions of 3.0 MPa and 523 K, the observed turnover-frequency of CO2 hydrogenation reached 1.15 × 10−2 s−1 over the 16%Pd0.1Zn1/CNTs(h-type). This value was 1.17 and 1.18 times that (0.98 × 10−2 and 0.97 × 10−2 s−1) of the 35%Pd0.1Zn1/AC and 20%Pd0.1Zn1/γ-Al2O3 catalysts with the respective optimal Pd0.1Zn1-loading. Using the MWCNTs in place of AC or γ-Al2O3 as the catalyst support displayed little change in the apparent activation energy for the CO2 hydrogenation, but led to an increase of surface concentration of the Pd0-species in the form of PdZn alloys, a kind of catalytically active Pd0-species closely associated with the methanol generation. On the other hand, the MWCNT-supported Pd–ZnO catalyst could reversibly adsorb a greater amount of hydrogen at temperatures ranging from room temperature to 623 K. This unique feature would help to generate a micro-environment with higher concentration of active H-adspecies at the surface of the functioning catalyst, thus increasing the rate of surface hydrogenation reactions. In comparison with the “Parallel-type (p-type)” MWCNTs, the “Herringbone-type (h-type)” MWCNTs possess more active surface (with more dangling bonds), and thus, higher capacity for adsorbing H2, which make their promoting action more remarkable. 相似文献
15.
Huan-ping Wang Shi-qing Xu Shui-qin Lu shi-long Zhao Bao-ling Wang 《Ceramics International》2009,35(7):2715-2718
The effects of B2O3 additives on the sintering behavior, microstructure and dielectric properties of CaSiO3 ceramics have been investigated. The B2O3 addition resulted in the emergence of CaO–B2O3–SiO2 glass phase, which was advantageous to lower the synthesis temperature of CaSiO3 crystal phase, and could effectively lower the densification temperature of CaSiO3 ceramic to as low as 1100 °C. The 6 wt% B2O3-doped CaSiO3 ceramic sintered at 1100 °C possessed good dielectric properties: r = 6.84 and tan δ = 6.9 × 10−4 (1 MHz). 相似文献
16.
The degradation of hydroquinone (HQ) and nalidixic acid (NA) mediated by TiO2 and iron oxide immobilized on functionalized polyvinyl fluoride films (PVFf–TiO2–Fe oxide) in the presence of H2O2 under simulated solar light has been examined. The results show that the contribution of homogeneous photo-Fenton oxidation to the initial mineralization process was low. The degradation rates were not dependant of initial pH. Heterogeneous photocatalytic activity of PVFf–TiO2–Fe oxide was enhanced by increasing temperature, NaCl addition and by long-term utilization.The PVFf–TiO2–Fe oxide surface was characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) at different states of utilization. Correlations between the catalyst surface composition and degradation kinetics are discussed. Long-term stability evaluated by repetitive pollutant degradations was outstanding. The presence of TiO2 seems to (i) limit contact between polymer film and highly reactive radicals in the solution and (ii) act as a charge trap. Moreover, during the photocatalysis mediated by PVFf–TiO2–Fe oxide, some leaching of supported iron increased the amount of the top TiO2 layer exposed to the light increasing the synergistic effects between the two oxides leading to enhanced pollutant degradation. 相似文献
17.
Guoyi Bai Xinxin Fan Hailong Wang Jianzhong Xu Fei He Huisen Ning 《Catalysis communications》2009,10(15):2031-2035
Co-precipitation, impregnation and ultrasonic sol–gel (USG) methods have been used to prepare Cu–Cr–Fe/γ-Al2O3 catalysts, which were further used to synthesize 2-methylpiperazine. The catalysts were characterized by XRD, XPS, TG/DSC, BET, TPR, AAS and TEM. It is found that preparation method can greatly impact the catalytic performance of the catalysts, the Cu–Cr–Fe/γ-Al2O3 catalyst prepared by the ultrasonic sol–gel method proved to be the most active and stable for this reaction. The dispersion and stabilization of Cu0 in the reduced catalysts are attributed to the existence of CuCr2O4 and Fe2O3. A surprising copper migration was detected by XPS analysis for the Cu–Cr–Fe/γ-Al2O3-USG catalyst after the calcination process, which may be crucial to the high activity and stability of this catalyst. 相似文献
18.
J. B. Wang K. Li X. L. Zhong Y. C. Zhou X. S. Fang C. C. Tang Y. Bando 《Nanoscale research letters》2009,4(10):1135-1140
The field emission properties of SnO2 nanowires fabricated by chemical vapor deposition with metallic catalyst-assistance were investigated. For the as-fabricated
SnO2 nanowires, the turn-on and threshold field were 4.03 and 5.4 V/μm, respectively. Considerable enhancement of field emission
of SnO2 nanowires was obtained by a post-annealing process in oxygen at high temperature. When the SnO2 nanowires were post-annealed at 1,000 °C in oxygen, the turn-on and threshold field were decreased to 3.77 and 4.4 V/μm,
respectively, and the current density was increased to 6.58 from 0.3 mA/cm2 at the same applied electric field of 5.0 V/μm. 相似文献
19.
Steven Corthals Joris Van Nederkassel Jan Geboers Hendrik De Winne Jasper Van Noyen Bart Moens Bert Sels Pierre Jacobs 《Catalysis Today》2008,138(1-2):28
Dry reforming of methane was studied over Ni catalysts supported on γAl2O3, CeO2, ZrO2 and MgAl2O4 (670 °C, 1.5 bar, 16–20 l CH4 mlcatalyst−1 h−1). It is shown that MgAl2O4 supported Ni catalysts promoted with both CeO2 and ZrO2 are promising catalysts for dry reforming of methane with carbon dioxide. Within a certain composition range, the simultaneous promotion with CeO2 and ZrO2 has great influence on the amount of coke and the catalyst service time. XRD analyses indicate that formation of crystalline CexZr1−xO2 mixed oxide phases occurs on double promotion. In particular, incorporation of low amounts of Zr in the CeO2 fluorite structure provides stable dry reforming catalysis. As shown with TPR, promotion leads to a higher reduced state of Ni. SEM, XRD and TPR analyses demonstrate that highly dispersed, doubly promoted Ni catalysts with a strong metal-support interaction are essential for stable dry reforming and suppression of the formation of carbon filaments. 相似文献
20.
Komateedi N. Rao Benjaram M. Reddy B. Abhishek Yeong-Hui Seo Nanzhe Jiang Sang-Eon Park 《Applied catalysis. B, Environmental》2009,91(3-4):649-656
The present study was undertaken to investigate the influence of ceria on the physicochemical and catalytic properties of V2O5/TiO2–ZrO2 for oxidative dehydrogenation of ethylbenzene to styrene utilizing CO2 as a soft oxidant. Monolayer equivalents of ceria, vanadia and ceria–vanadia combination over TiO2–ZrO2 (TZ) support were impregnated by a coprecipitation and wet impregnation methods. Synthesized catalysts were characterized by using X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, temperature programmed reduction, transmission electron microscopy and BET surface area methods. The XRD profiles of 550 °C calcined samples revealed amorphous nature of the materials. Upon increasing calcination temperature to 750 °C, in addition to ZrTiO4 peaks, few other lines due to ZrV2O7 and CeVO4 were observed. The XPS V 2p results revealed the existence of V4+ and V5+ species at 550 and 750 °C calcinations temperatures, respectively. TEM analysis suggested the presence of nanosized (<7 nm) particles with narrow range distribution. Raman measurements confirmed the formation ZrTiO4 under high temperature treatments. TPR measurements suggested a facile reduction of CeO2–V2O5/TZ sample. Among various samples evaluated, the CeO2–V2O5/TZ sample exhibited highest conversion and nearly 100% product selectivity. In particular, the addition of ceria to V2O5/TZ suppressed the coke deposition and allowed a stable and high catalytic activity. 相似文献