Effect of acid on the crystalline phase of TiO2 prepared by hydrothermal treatment and its application in the oxidative steam reforming of methanol

Eaimsumang, Srisin; Prataksanon, Piyachat; Pongstabodee, Sangobtip; Luengnaruemitchai, Apanee

doi:10.1007/s11164-019-04031-8

Cited by 19 publications

(4 citation statements)

References 48 publications

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“…Griboski et al [11] ascribe the system reactivity of the system Zn/TiO 2 to the zinc titanate presence and Deshmane et al [12] relate the reactivity to the TiO 2 dispersion, no consideration about zinc textural properties are reported and there is no ZnO evidence. Eaimsumang et al [13] studied the effect of the morphology and crystalline phases of pristine TiO 2 on oxidative steam reforming of methanol, showing that rutile or mixed phases are more active than anatase.…”

Section: Introductionmentioning

confidence: 99%

The effect of nanocrystalline TiO2 on structure and catalytic activity of CuO–ZnO in combined methanol reforming

Pinzari¹

2023

Reac Kinet Mech Cat

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CuO–ZnO (CZ) and CuO–ZnO/TiO2 (CZT) catalysts have been prepared by co-precipitation, characterized by X-ray diffraction, surface area measurements and chemical analysis and tested in the combined methanol reforming reaction. Catalytic tests have been performed in the temperature range 200–400 °C with a GHSV = 55.000 h−1, after H2 reducing pretreatment at 250 °C or 450 °C. It is shown that nanocrystalline TiO2 influences the CuO–ZnO nanosized structure, reducibility and reactivity. TiO2 slightly increases ZnO crystallite size of the fresh catalyst. Moreover, it causes the CuO chemical reduction to nanosized Cu2O on exhaust catalyst pretreated in hydrogen at 250 °C, this improves the reaction with higher methanol conversion and hydrogen production. On the contrary, TiO2 reduces CuO to submicron Cu0 and greatly increases ZnO crystallite size on the exhaust catalyst pretreated in hydrogen at 450 °C, this treatment weakens the reaction, with lower methanol conversion and hydrogen production. In both cases, nanocrystalline TiO2 presence is able to decrease the CO formation: independently of the hydrogen pretreatment temperature. This ability of the nanocrystalline TiO2 is ascribed to the presence of the oxygen vacancies, which act as electron donors that contribute to hinder CO2 and H2 surface adsorption for steric, electrostatic and probabilistic factors.

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Section: Introductionmentioning

confidence: 99%

The effect of nanocrystalline TiO2 on structure and catalytic activity of CuO–ZnO in combined methanol reforming

Pinzari¹

2023

Reac Kinet Mech Cat

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“…However, using various acids affects the micro-structural and optical, and photocatalytic properties of TiO 2 . For example, incorporating HCl, acetylacetone, or acetic acid as acid catalysts during the preparation of titania precursor results in a bandgap energy that is larger (ranging from 3.3 to 3.7 eV) [20,21] compared to the theoretical bandgap energy (3.0-3.2 eV) of TiO 2 .…”

Section: Introductionmentioning

confidence: 99%

Phase Composition, Microstructure, and Optical Characteristics of Spin‐Coated La‐TiO₂ and Fe–TiO₂

Liboon

Cabo

Unabia

et al. 2023

Physica Status Solidi (a)

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Herein, TiO 2 , La-added, and Fe-added TiO 2 coatings are synthesized by sol-gel spin coating using acid catalyst-free titania precursors, and their microstructural and optical characteristics are studied. The possible reaction mechanism for synthesizing TiO 2 -based coatings using catalyst-free precursor is presented and correlated to their microstructural characteristic. TiO 2 coatings are developed and found to be anatase in phases having submicron morphological features. The anatase composition of TiO 2 coating decreases with increasing La or Fe ion concentrations. This manifests the inhibitory effect of increasing La and Fe ions to the formation of anatase TiO 2 . Moreover, the addition of La ions caused no significant changes in the reflectance spectra and bandgap energy of TiO 2 . In contrast, a remarkable red shift was observed with increasing Fe ion concentration. The calculated bandgap decreases from 3.261 to 2.096 eV with the addition of 7.5 mol% Fe ions, attributed to the formation of new energy states below the conduction band of TiO 2 induced by the Fe ion. These results suggested that a low-cost Fe added-TiO 2 material can be synthesized using an acid catalyst-free precursor that could extend the photocatalytic efficiency of TiO 2 to the visible light region.

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“…On the other hand, in materials science related research TPR is often used to study phase changes, growth, nucleation, diffusion, and related kinetics, all led to the development of different models over the years [11][12][13][14]. In general, two temperature domains exist during TPR, one at a low temperature (up to 250-300 • C) mostly due to the reduction of dispersed metal oxide clusters/particles to metals [15] and the other above that, and can have a contribution from the reduction of the support (in the case of reducible oxides) such as TiO 2 , CeO 2 , and Fe 2 O 3 , among others [16][17][18]. The majority of TPR studies are conducted for more commonly used noble metals such as Pt, Pd and Rh while Ir has received less attention.…”

Section: Introductionmentioning

confidence: 99%

Study of the Kinetics of Reduction of IrO2 on TiO2 (Anatase) by Temperature-Programmed Reduction

et al. 2023

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The interaction between IrO2 and TiO2 (anatase) in non-isothermal reduction conditions has been studied by the temperature programmed reduction technique. IrO2 clusters are of sizes between 0.5 and 0.9 nm as determined from High Resolution Transmission Electron Microscopy (HRTEM). Largely, two main regions for reduction were found and modeled at ca. 100 and 230 °C. The first region is attributed to the partial reduction of IrO2 clusters, while the second one is due to reduction of the formed crystalline (rutile IrO2), during TPR, to Ir metal. Two methods for calculating kinetic parameters were tested. First, by applying different ramping rates on a 3.5 wt.% IrO2/TiO2 using Kissinger’s method. The apparent activation energy values for the first and second reduction regions were found to be ca. 35 and 100 kJ/mol, respectively. The second method was based on fitting different kinetic models for the experimental results in order to extract qualitative information on the nature of interaction during the reduction process. It was found that the first reduction is largely due to the amount of IrO2 (reactant concentration) while the second one involved phase boundary effect as well as nucleation.

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Effect of acid on the crystalline phase of TiO2 prepared by hydrothermal treatment and its application in the oxidative steam reforming of methanol

Cited by 19 publications

References 48 publications

The effect of nanocrystalline TiO2 on structure and catalytic activity of CuO–ZnO in combined methanol reforming

The effect of nanocrystalline TiO2 on structure and catalytic activity of CuO–ZnO in combined methanol reforming

Phase Composition, Microstructure, and Optical Characteristics of Spin‐Coated La‐TiO₂ and Fe–TiO₂

Study of the Kinetics of Reduction of IrO2 on TiO2 (Anatase) by Temperature-Programmed Reduction

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Effect of acid on the crystalline phase of TiO2 prepared by hydrothermal treatment and its application in the oxidative steam reforming of methanol

Cited by 19 publications

References 48 publications

The effect of nanocrystalline TiO2 on structure and catalytic activity of CuO–ZnO in combined methanol reforming

The effect of nanocrystalline TiO2 on structure and catalytic activity of CuO–ZnO in combined methanol reforming

Phase Composition, Microstructure, and Optical Characteristics of Spin‐Coated La‐TiO2 and Fe–TiO2

Study of the Kinetics of Reduction of IrO2 on TiO2 (Anatase) by Temperature-Programmed Reduction

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Phase Composition, Microstructure, and Optical Characteristics of Spin‐Coated La‐TiO₂ and Fe–TiO₂