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Bunsho Ohtani - One of the best experts on this subject based on the ideXlab platform.
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enhanced photocatalytic activity of bismuth tungsten mixed oxides for Oxidative Decomposition of acetaldehyde under visible light irradiation
Catalysis Communications, 2012Co-Authors: Fumiaki Amano, Kohei Nogami, Bunsho OhtaniAbstract:Abstract Russelite bismuth tungstate (Bi 2 WO 6 ) flake-ball particles prepared by a hydrothermal reaction method have been reported to be visible-light-responsive photocatalysts for mineralization of organic compounds. Here, we report new bismuth-tungsten mixed oxide particles with a tungsten-to-bismuth ratio (W/Bi ratio) in feed of 1.0, which is two-times higher than the stoichiometric ratio of Bi 2 WO 6 (W/Bi = 0.50). Compared to the conventional Bi 2 WO 6 flake-ball particles, the tungsten-rich particles exhibited a narrow band gap (2.70 eV), large specific surface area due to the rectangular platelet nanostructure, and high level of photocatalytic activity for Oxidative Decomposition of acetaldehyde.
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role of molecular oxygen in photocatalytic Oxidative Decomposition of acetic acid by metal oxide particulate suspensions and thin film electrodes
Electrochemistry, 2008Co-Authors: Bunsho Ohtani, Yasuyuki NoharaAbstract:The role of molecular oxygen (O2) in the photocatalytic Decomposition of a model compound, acetic acid, was studied using suspensions and electrodes of metal oxide particles, titanium(IV) oxide (TiO2) or tungsten(VI) oxide (WO3). Results for photocurrent efficiency in photoelectrochemical measurements revealed that reaction of O2 with radicals liberated by positive holes increases the overall rate of photocatalytic Oxidative Decomposition of acetic acid.
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development of a novel photocatalytic reaction system for Oxidative Decomposition of volatile organic compounds in water with enhanced aeration
Journal of Photochemistry and Photobiology A-chemistry, 2003Co-Authors: Roberto Villacres, Shigeru Ikeda, Tsukasa Torimoto, Bunsho OhtaniAbstract:Abstract A novel photocatalytic reaction system, composed of solution and gas spaces that are divided by a thin Teflon film and titanium(IV) oxide (TiO2)-coated mesh or cloth, for the treatment of contaminated aqueous solutions was developed to be operated with enhanced aeration without bubbling of air in the solution. First, the photocatalytic activities of TiO2 particles immobilized on two kinds of support material, stainless steel mesh (SSM) and fiberglass cloth (FGC), were investigated for photocatalytic oxidation of 2-propanol, as a model volatile organic compound, dissolved in aerated aqueous solution. The TiO2 particles immobilized on both support materials exhibited photocatalytic activity to oxidize 2-propanol into acetone and carbon dioxide (CO2), and the activity levels of the TiO2 particles immobilized on the two kinds of support materials were comparable. Presumably due to the presence of a small amount of metal species originating in SSM that might work as reduction catalysts, molecular hydrogen (H2) was also liberated on the TiO2-immobilized SSM. Results of analysis of weight loss after photoirradiation suggested that the stability of the TiO2-immobilized FGC was better than that of the TiO2-immobilized SSM. On the basis of these results, FGC was employed in construction of a photocatalytic reactor equipped with an oxygen (O2)-permeable Teflon membrane in order to make oxygen pass from a gas space to a solution space and to keep the surface of the immobilized TiO2 photocatalyst, facing an aqueous solution containing volatile organic compounds, saturated with dissolved O2. From the results of photocatalytic Oxidative Decomposition of 2-propanol, it was clarified that the surfaces of TiO2 particles could be sufficiently supplied with O2 from the gas space through the membrane to accelerate the oxidation.
Azfar Hassan - One of the best experts on this subject based on the ideXlab platform.
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nanosize effects of nio nanosorbcats on adsorption and catalytic thermo Oxidative Decomposition of vacuum residue asphaltenes
Canadian Journal of Chemical Engineering, 2017Co-Authors: Nedal N Marei, Amjad Elqanni, Nashaat N Nassar, Gerardo Vitale, Maryam Hmoudah, Azfar HassanAbstract:The nanosize effects of NiO nanosorbcats on adsorption and post-adsorption catalytic thermo-Oxidative Decomposition of vacuum residue (VR) n-C5 asphaltenes was investigated using a UV-vis spectrophotometer and thermogravimetric analyzer coupled with a mass spectrometer and presented in this study. Sizes between 5 and 80 nm of different-sized NiO nanosorbcats were employed. Batch adsorption experiments were carried out for the considered asphaltenes in toluene solutions, monitored via UV-vis spectrophotometry. The macroscopic adsorption isotherms were described by implementing the solid-liquid equilibrium (SLE) model. The findings showed that thermally cracked vacuum residue (VR) n-C5 asphaltenes interact to different extents with different-sized NiO nanosorbcats. A normalized surface area basis was used for the amount of VR n-C5 asphaltene adsorbed per nm2 of NiO surface, which was the highest for NiO nanoparticles of size 80 nm, with 5 nm size being the lowest. Thermogravimetric analysis of VR n-C5 asphaltenes was also achieved and the reaction products were explored by a mass spectrometer. The Kissinger-Akahira-Sunose (KAS) isoconversional model was used to describe the reaction mechanism and to confirm the validity of the catalytic role of the different particle sizes of NiO nanosorbcats. The highest catalytic activity was for smallest NiO when compared to the highest NiO nanosorbcats. Furthermore, the results of thermodynamic transition state parameters of activation; changes in Gibbs free energy (ΔG‡), entropy (ΔS‡), and enthalpy (ΔH‡) highlighted the catalytic activity of NiO nanosorbcats towards VR n-C5 asphaltenes oxidation. These findings exhibit the significance of textural properties and nanosize of nanoparticles during adsorption and thermal catalytic processing of asphaltenes. This article is protected by copyright. All rights reserved
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theoretical and thermogravimetric study on the thermo Oxidative Decomposition of quinolin 65 as an asphaltene model molecule
RSC Advances, 2016Co-Authors: Ismail Badran, Nashaat N Nassar, Nedal N Marei, Azfar HassanAbstract:In this study, the thermal oxidation of an asphaltene model molecule, Quinolin-65, was investigated using the density functional theory (DFT) and the second-order Moller–Plesset (MP2) perturbation theory. The reactions studied involved thermal Decompositions as well as the interactions between the model molecule and singlet atomic (O1D) and molecular (O21Δ) oxygen. The theoretical study was performed under conditions similar to those of the uncatalyzed thermal oxidation of asphaltenes. A new reaction pathway for the loss of the olefin chain in Quinolin-65 via a 1,3-hydrogen shift mechanism was revealed. Thermogravimetric analysis of Quinolin-65 was also performed and the reaction products were probed by a mass spectrometer. Both the theoretical study and the thermogravimetric analysis concluded that the thermo-Oxidative Decomposition of Quinolin-65 is a complex multi-step reaction process, which involves different reaction pathways. The thermodynamic parameters obtained in this study showed that the reaction process should start with the loss of the olefin chain in the Quinolin-65 molecule, followed by the oxidation of the aromatic chain, to produce mainly, H2O, CO2, and SO2.
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maghemite nanosorbcats for methylene blue adsorption and subsequent catalytic thermo Oxidative Decomposition computational modeling and thermodynamics studies
Journal of Colloid and Interface Science, 2016Co-Authors: Amjad Elqanni, Nashaat N Nassar, Gerardo Vitale, Azfar HassanAbstract:Abstract In this study methylene blue (MB) has been investigated for its adsorption and subsequent catalytic thermo-Oxidative Decomposition on surface of maghemite (γ-Fe2O3) nanoparticles. The experimental adsorption isotherm fit well to the Freundlich model, indicating multi-sites adsorption. Computational modeling of the interaction between the MB molecule and γ-Fe2O3 nanoparticle surface was carried out to get more insights into its adsorption behavior. Adsorption energies of MB molecules on the surface indicated that there are different adsorption sites on the surface of γ-Fe2O3 confirming the findings regarding the adsorption isotherm. The catalytic activity of the γ-Fe2O3 nanoparticles toward MB thermo-Oxidative Decomposition has been confirmed by subjecting the adsorbed MB to a thermo oxidation process up to 600 °C in a thermogravimetric analyzer. The experimental results showed a catalytic activity for post adsorption oxidation. The oxidation kinetics were studied using the Ozawa–Flyn–Wall (OFW) corrected method. The most probable mechanism functions were fifth and third orders for virgin MB and MB adsorbed onto γ-Fe2O3 nanoparticles, respectively. Moreover, the results of thermodynamic transition state parameters, namely changes in Gibbs free energy of activation ( Δ G ‡ ) , enthalpy of activation ( Δ H ‡ ) , and entropy of activation ( Δ S ‡ ) , emphasized the catalytic activity of γ-Fe2O3 nanoparticles toward MB oxidation.
Toshio Okuhara - One of the best experts on this subject based on the ideXlab platform.
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selective Oxidative Decomposition of ammonia in neutral water to nitrogen over titania supported platinum or palladium catalyst
Applied Catalysis A-general, 2000Co-Authors: Junji Taguchi, Toshio OkuharaAbstract:Abstract Selective Oxidative Decomposition of NH3 (1000 ppm) in water to N2 (wet oxidation) was achieved with precious metal-supported catalysts at 433 K under 8 atm of O2 without alkalization of the solution. As a support for Pt, an anatase TiO2 (P-25) was superior in activity, while NO2− and NO3− were formed at concentrations of about 3 and 4 ppm, respectively, at 6 h. The activity for N2 formation was in the order of Pt > Ru > Pd > Rh ⪢ Cu, Co, and Ni, when the TiO2 (P-25) was used as the support. It was further found that Pd/TiO2 (P-25) gave 100% selectivity to N2; no undesirable NO2− and NO3− were detected in the solution nor any N2O in the gas phase. Increase in the loading amount of Pd from 0.25 to 1.0 wt% on TiO2 (P-25) effectively enhanced catalytic activity, while retaining high selectivity.
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selective Oxidative Decomposition of ammonia in water to nitrogen catalyzed by platinum supported titania
Chemistry Letters, 1999Co-Authors: Junji Taguchi, Teruyuki Nakato, Toshio OkuharaAbstract:Selective Oxidative Decomposition of NH3 (or NH4+) in water to N2 was achieved with 0.5 wt%Pt/TiO2 catalyst at 433 K under 8 atm of O2 without alkalization of the solution; NH3 of 1000 ppm was exclusively converted to N2 and undesirable products, NO2− and NO3− in the solution and N2O in the gas phase were little formed.
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catalytic removal of trimethylamine an offensive odor component by selective Oxidative Decomposition to n2 co2 and h2o over copper exchanged zeolites
Chemistry Letters, 1992Co-Authors: Hiroki Kuwabara, Toshio Okuhara, Makoto MisonoAbstract:Copper-exchanged zeolites catalyzed the Oxidative Decomposition of (CH3)3N to N2, CO2, and H2O. The selectivity to N2 was 92% and the formation of NOx was less than 5 ppm, when 8000 ppm of (CH3)3N with O2 (20%) was flowed over copper-exchanged Y zeolite at 573 K.
Lijuan Yuan - One of the best experts on this subject based on the ideXlab platform.
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visible light induced efficiently Oxidative Decomposition of p nitrophenol by cdte tio2 nanotube arrays
Chemical Engineering Journal, 2013Co-Authors: Hui Feng, Thanhthuy Tran T, Lan Chen, Lijuan YuanAbstract:Abstract The photocatalytically Oxidative Decomposition of p-Nitrophenol (PNP) with the CdTe nanoparticles-modified TiO 2 nanotube arrays (CdTe/TiO 2 NTAs) as catalyst was investigated under visible light (400 nm λ 2 NTAs show much higher degradation rate (0.0312 min −1 ) than the unmodified TiO 2 NTAs (0.0071 min −1 ). The enhanced photocatalytic activity is attributed to the extended absorption in the visible light resulting from the narrow-band-gap semiconductor CdTe and the effective separation of photogenerated carriers. The photocatalytic activity of the photocatalyst is decreased by hole scavengers, indicating an Oxidative degradation route with the photogenerated holes acting as the oxidant.
Arnaud Demortiere - One of the best experts on this subject based on the ideXlab platform.
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Oxidative Decomposition products of synthetic NaFePO4 marićite: nano-textural and electrochemical characterization
European Journal of Mineralogy, 2019Co-Authors: Fabrice Brunet, Camille Crouzet, Sorina Cretu, Renald David, Matthieu Courty, Arnaud Demortiere, Nadir RechamAbstract:44 Single-phase maricite, NaFePO4, was synthesized from monosodium phosphate and 45 iron oxalate at 750°C, at atmospheric pressure. Thermal treatment of synthetic maricite in air 46 indicated Oxidative Decomposition into Na3Fe 3+ 2(PO4)3 nasicon and-Fe2O3 at temperatures 47 above 225°C. Intergrowth of the reaction products is found to occur at the nanoscale without 48 identified crystallographic relationship with the maricite precursor. Electrochemical activity of 49 the reaction product is confirmed with the reversible insertion of one Na at 2.55 V vs Na + /Na 0. 50 Keywords: sodium iron phosphate; maricite; sodium-ion batteries; Oxidative Decomposition; 51 NASICON 52 53 54
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Oxidative Decomposition products of synthetic nafepo4 maricite nano textural and electrochemical characterization
European Journal of Mineralogy, 2019Co-Authors: Fabrice Brunet, Camille Crouzet, Sorina Cretu, Renald David, Matthieu Courty, Arnaud DemortiereAbstract:44 Single-phase maricite, NaFePO4, was synthesized from monosodium phosphate and 45 iron oxalate at 750°C, at atmospheric pressure. Thermal treatment of synthetic maricite in air 46 indicated Oxidative Decomposition into Na3Fe 3+ 2(PO4)3 nasicon and-Fe2O3 at temperatures 47 above 225°C. Intergrowth of the reaction products is found to occur at the nanoscale without 48 identified crystallographic relationship with the maricite precursor. Electrochemical activity of 49 the reaction product is confirmed with the reversible insertion of one Na at 2.55 V vs Na + /Na 0. 50 Keywords: sodium iron phosphate; maricite; sodium-ion batteries; Oxidative Decomposition; 51 NASICON 52 53 54
