An effect of iron(III) oxides crystallinity on their catalytic efficiency and applicability in phenol degradation—A competition between homogeneous and heterogeneous catalysis

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.     

Morphology-dependent redox and catalytic properties of CeO2 nanostructures: Nanowires, nanorods and nanoparticles

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.     

Performance of Pd catalysts supported on nanocrystalline α-Al2O3 and Ni-modified α-Al2O3 in selective hydrogenation of acetylene

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.     

The phenol steam reforming reaction towards H2 production on natural calcite

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).     

Visible light-induced photocatalytic activity of delafossite AgMO2 (M = Al, Ga, In) prepared via a hydrothermal method

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.     

Synergistic effect of TiO2 and iron oxide supported on fluorocarbon films. Part 1: Effect of preparation parameters on photocatalytic degradation of organic pollutant at neutral pH

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 PVF^f–TiO₂. The possible mechanistic pathway for the TiO₂ deposition and the nature of the polymer–TiO₂ interaction are discussed. Furthermore PVF and PVF^f–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 PVF^f–TiO₂–Fe oxide respectively.HQ degradation and mineralization mediated by PVF^f–TiO₂, PVF–Fe oxide and PVF^f–TiO₂–Fe oxide were investigated under different conditions. Remarkable synergistic effects were observed for PVF^f–TiO₂–Fe oxide possibly due to Fe(II) regeneration, accelerated by electron transfer from TiO₂ to the iron oxide under light.     

Photodegradation of tetrahalobisphenol-A (X = Cl, Br) flame retardants and delineation of factors affecting the process

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 (pH_pzc; 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 (pK_as ca. 9.6–11.3), even though the number of OH radicals continued to increase at the higher pHs.     

Impact of supercritical drying and heat treatment on physical properties of titania/silica aerogel monolithic and its applications

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.     

CO hydrogenation to iso-C4 hydrocarbons over CeO2–TiO2 catalysts

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.     

Oriented polycrystalline mesoporous CeO2 with enhanced pore integrity

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.     

Decomposition of ozone on Ag/SiO2 catalyst for abatement of waste gases emissions

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.     

Study of ruthenium supported on Ta2O5–ZrO2 and Nb2O5–ZrO2 as catalysts for the partial oxidation of methane

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.     

Structure and magnetic properties of Fe1−xCox nanowires in self-assembled arrays

Fe_1−xCo_x 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 Fe_1−xCo_x changed with their compositions, which may be attributable to shape anisotropy. The room temperature ⁵⁷Fe Mössbauer spectra of the arrays of the Fe_1−xCo_x nanowires revealed strong shape anisotropy.     

Carbon nanotube-supported Pd–ZnO catalyst for hydrogenation of CO2 to methanol

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%Pd_0.1Zn₁/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%Pd_0.1Zn₁/AC and 20%Pd_0.1Zn₁/γ-Al₂O₃ catalysts with the respective optimal Pd_0.1Zn₁-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.     

Dielectric properties and microstructures of CaSiO3 ceramics with B2O3 addition

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).     

Synergistic effect of TiO2 and iron oxide supported on fluorocarbon films: Part 2: Long-term stability and influence of reaction parameters on photoactivated degradation of pollutants

The degradation of hydroquinone (HQ) and nalidixic acid (NA) mediated by TiO₂ and iron oxide immobilized on functionalized polyvinyl fluoride films (PVF^f–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 PVF^f–TiO₂–Fe oxide was enhanced by increasing temperature, NaCl addition and by long-term utilization.The PVF^f–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 PVF^f–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.     

Effects of the preparation methods on the performance of the Cu–Cr–Fe/γ-Al2O3 catalysts for the synthesis of 2-methylpiperazine

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.     

Considerable Enhancement of Field Emission of SnO2 Nanowires by Post-Annealing Process in Oxygen at High Temperature

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.     

Influence of composition of MgAl2O4 supported NiCeO2ZrO2 catalysts on coke formation and catalyst stability for dry reforming of methane

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 ml_catalyst⁻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 Ce_xZr_1−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.     

Effect of ceria on the structure and catalytic activity of V2O5/TiO2–ZrO2 for oxidehydrogenation of ethylbenzene to styrene utilizing CO2 as soft oxidant

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.