Synthesis and characterization of packed mesoporous tungsteno-silicates: application to the catalytic dehydrogenation of 2-propanol

Trens, Philippe; Stathopoulos, Vassilis N.; Hudson, Michael J.; Pomonis, P.J.

doi:10.1016/j.apcata.2003.12.004

Cited by 17 publications

(12 citation statements)

References 27 publications

(23 reference statements)

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“…The corresponding adsorption-desorption isotherms are depicted in Figure 1b. In all cases, maxima at pore diameters higher than 3 nm are obtained, implying the presence of mesopores which can be further corroborated by the existence of adsorption-desorption isotherms of type IV with hysteresis loop at a relative pressure above 0.5 ( Figure 1b) [33,35,46,47]. As observed in Table 1 and Figure 1a, the incorporation of iron into the ceria lattice results in a decrease in pore volume and average pore diameter, with the sample of rod-like morphology exhibiting the highest reduction percentages (60% and 53%, respectively), while nanocubes and nanopolyhedra show a much lower percentage decrease, namely 27% and 29% in pore volume and 15% and 3.8% in average pore diameter, respectively.…”

Section: Textural and Structural Characteristics (Bet/xrd)supporting

confidence: 62%

Facet-Dependent Reactivity of Fe2O3/CeO2 Nanocomposites: Effect of Ceria Morphology on CO Oxidation

et al. 2019

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Ceria has been widely studied either as catalyst itself or support of various active phases in many catalytic reactions, due to its unique redox and surface properties in conjunction to its lower cost, compared to noble metal-based catalytic systems. The rational design of catalytic materials, through appropriate tailoring of the particles’ shape and size, in order to acquire highly efficient nanocatalysts, is of major significance. Iron is considered to be one of the cheapest transition metals while its interaction with ceria support and their shape-dependent catalytic activity has not been fully investigated. In this work, we report on ceria nanostructures morphological effects (cubes, polyhedra, rods) on the textural, structural, surface, redox properties and, consequently, on the CO oxidation performance of the iron-ceria mixed oxides (Fe2O3/CeO2). A full characterization study involving N2 adsorption at –196 °C, X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), temperature programmed reduction (TPR), and X-ray photoelectron spectroscopy (XPS) was performed. The results clearly revealed the key role of support morphology on the physicochemical properties and the catalytic behavior of the iron-ceria binary system, with the rod-shaped sample exhibiting the highest catalytic performance, both in terms of conversion and specific activity, due to its improved reducibility and oxygen mobility, along with its abundance in Fe2+ species.

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Section: Textural and Structural Characteristics (Bet/xrd)supporting

confidence: 62%

Facet-Dependent Reactivity of Fe2O3/CeO2 Nanocomposites: Effect of Ceria Morphology on CO Oxidation

et al. 2019

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“…From these values and applying the Arrhenius equation, the corresponding values of apparent activation energy (Ea) and the preexponential factor (k o ) have been calculated for each ACM and they are summarized in Table 2. The values that were obtained for the apparent activation energies were quite similar, ranging from 100 to 130 kJ/mol and of the same order than those that were obtained for different inorganic catalysts (heteropolyacids, zeolites,…) [38,39] and powder activated carbons that were obtained by chemical activation with phosphoric acid from different lignocellulosic waste [11,15].…”

Section: Resultsmentioning

confidence: 62%

Acid Mesoporous Carbon Monoliths from Lignocellulosic Biomass Waste for Methanol Dehydration

et al. 2019

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Activated carbon monoliths (ACMs), with 25 cells/cm2, were prepared from the direct extrusion of Alcell, Kraft lignin and olives stones particles that were impregnated with phosphoric acid, followed by activation at 700 °C. These ACMs were used as catalysts for methanol dehydration reaction under air atmosphere. ACM that was prepared from olive stone and at impregnation ratio of 2, OS2, showed the highest catalytic activity, with a methanol conversion of 75%, a selectivity to dimethyl ether (DME) higher than 90%, and a great stability under the operating conditions studied. The results suggest that the monolithic conformation, with a density channel of 25 cells/cm2 avoid the blockage of active sites by coke deposition to a large extent. Methanol conversion for OS2 was reduced to 29% in the presence of 8%v water, at 350 °C, although the selectivity to DME remained higher than 86%. A kinetic model of methanol dehydration in the presence of air was developed, while taking into account the competitive adsorption of water. A Langmuir-Hinshelwood mechanism, whose rate-limiting step was the surface reaction between two adsorbed methanol molecules, represented the experimental data under the conditions studied very well. An activation energy value of 92 kJ/mol for methanol dehydration reaction and adsorption enthalpies for methanol and water of −12 and −35 kJ/mol, respectively, were obtained.

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“…X-ray diffraction (XRD) measurement was carried out using a Rigaku D/Max-IIIC diffractometer (RIGAKU Corp; Tokyo, Japan) with CuKα radiation (λ = 0.1541 nm) over the range 2θ = 10-70 • at room temperature, operated at 35 kV and 25 mA at the rate of 3 • /min scan speed [25][26][27]. Fourier transform infrared (FTIR) spectroscopy was performed on a PerkinElmer FT-IR spectrometer (Thermo Fisher Scientific, Leicestershire, UK) employing attenuated total reflection (ATR) method.…”

Section: Characterization Of Catalystsmentioning

confidence: 99%

“…Fourier transform infrared (FTIR) spectroscopy was performed on a PerkinElmer FT-IR spectrometer (Thermo Fisher Scientific, Leicestershire, UK) employing attenuated total reflection (ATR) method. A Brunauer-Emmett-Teller (BET) technique was recorded on the nitrogen adsorption-desorption at 76 K using a Micromeritics 3 Flex version 5.00 (Micromeritics, Norcross, GA, USA) after degassing [25][26][27]. Morphology of the synthesized materials was determined with scanning electron microscopy (SEM) ZEISS EVO LS10 (Carl Zeiss Microscopy, Hamburg, Germany), of 0.2-30 kV acceleration voltage and 0.5 pA-5 µA probe current, coupled to energy dispersive spectroscopy (EDS) detector (Carl Zeiss SmartEDX, Hamburg, Germany), with samples attached to sample holder and coated with gold using sputter-coating (SEM Coating System Machine).…”

Section: Characterization Of Catalystsmentioning

confidence: 99%

Enhanced Photocatalytic Activity of CuWO4 Doped TiO2 Photocatalyst Towards Carbamazepine Removal under UV Irradiation

et al. 2021

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Abatement of contaminants of emerging concerns (CECs) in water sources has been widely studied employing TiO2 based heterogeneous photocatalysis. However, low quantum energy yield among other limitations of titania has led to its modification with other semiconductor materials for improved photocatalytic activity. In this work, a 0.05 wt.% CuWO4 over TiO2 was prepared as a powder composite. Each component part synthesized via the sol-gel method for TiO2, and CuWO4 by co-precipitation assisted hydrothermal method from precursor salts, underwent gentle mechanical agitation. Homogenization of the nanopowder precursors was performed by zirconia ball milling for 2 h. The final material was obtained after annealing at 500 °C for 3.5 h. Structural and morphological characterization of the synthesized material has been achieved employing X-ray diffraction (XRD), Fourier transform infra-red (FTIR) spectroscopy, Brunauer–Emmett–Teller (BET) N2 adsorption–desorption analysis, Scanning electron microscopy-coupled Energy dispersive X-ray spectroscopy (SEM-EDS), Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and UV-Vis diffuse reflectance spectroscopy (UV-vis DRS) for optical characterization. The 0.05 wt.% CuWO4-TiO2 catalyst was investigated for its photocatalytic activity over carbamazepine (CBZ), achieving a degradation of almost 100% after 2 h irradiation. A comparison with pure TiO2 prepared under those same conditions was made. The effect of pH, chemical scavengers, H2O2 as well as contaminant ion effects (anions, cations), and humic acid (HA) was investigated, and their related influences on the photocatalyst efficiency towards CBZ degradation highlighted accordingly.

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Synthesis and characterization of packed mesoporous tungsteno-silicates: application to the catalytic dehydrogenation of 2-propanol

Cited by 17 publications

References 27 publications

Facet-Dependent Reactivity of Fe2O3/CeO2 Nanocomposites: Effect of Ceria Morphology on CO Oxidation

Facet-Dependent Reactivity of Fe2O3/CeO2 Nanocomposites: Effect of Ceria Morphology on CO Oxidation

Acid Mesoporous Carbon Monoliths from Lignocellulosic Biomass Waste for Methanol Dehydration

Enhanced Photocatalytic Activity of CuWO4 Doped TiO2 Photocatalyst Towards Carbamazepine Removal under UV Irradiation

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