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Showing papers on "Partial oxidation published in 2009"


Journal ArticleDOI
TL;DR: In this article, the mechanisms of Co/ceria catalyst deactivation during steam reforming, oxidative steam reforming and partial oxidation of ethanol were explored by comparing the results from different characterization techniques with those obtained from catalytic testing in a fixed-bed reactor.

211 citations


Journal ArticleDOI
Hideto Imai1, Koichi Izumi1, Masashi Matsumoto1, Yoshimi Kubo1, Kazuo Kato1, Yasuhiko Imai1 
TL;DR: XANES analysis indicated that the charge transfer from platinum to the adsorbed oxygen species was almost constant and rather small, that is, about 0.5 electrons per oxygen, up to two monolayers of oxygen, which means that ionic polarization hardly develops at this stage of the surface platinum's "oxide" growth.
Abstract: The electrochemical oxidation behaviors of the surfaces of platinum nanoparticles, one of the key phenomena in fuel cell developments, were investigated in situ and in real time, via time-resolved hard X-ray diffraction and energy dispersive X-ray absorption spectroscopy. Combining two complementary structural analyses, dynamical and inhomogenous structural changes occurring at the surfaces of nanoparticles were monitored on an atomic level with a time resolution of less than 1 s. After oxidation at 1.4 V vs RHE (reversible hydrogen electrode) in a 0.5 M H(2)SO(4) solution, longer Pt-O bonds (2.2-2.3 A that can be assigned to OHH and/or OH species) were first formed on the surface through the partial oxidation of water molecules. Next, these species turned to shorter Pt-O bonds (2.0 A, adsorbed atomic oxygen), and atomic oxygen was incorporated into the inner part of the nanoparticles, forming an initial monolayer oxide that had alpha-PtO(2)-like local structures with expanded Pt-Pt bonds (3.1 A). Finally, quasi-three-dimensional oxides with longer Pt-(O)-Pt bonds (3.5 A, precursor for beta-PtO(2)) grew on the surface, at almost 100 s after oxidation. Despite the very complex oxidation mechanism on the atomic level, XANES analysis indicated that the charge transfer from platinum to the adsorbed oxygen species was almost constant and rather small, that is, about 0.5 electrons per oxygen, up to two monolayers of oxygen. This means that ionic polarization hardly develops at this stage of the surface platinum's "oxide" growth.

192 citations


Journal ArticleDOI
TL;DR: With the addition of oxalate oxidase, these glycerol/air biofuel cells have yielded power densities of up to 1.32 mW cm–2, and have the ability to operate at high fuel concentrations.
Abstract: Glycerol has drawn increasing attention as a prospective fuel because it has many desirable qualities and is abundant due to the fact that it is a by-product of biodiesel production Qualities such as nontoxicity, extremely low vapour pressure, low flammability and high energy density make glycerol very appealing as an energy source Previous research has shown that partial oxidation of glycerol can occur at enzymatic bioanodes of biofuel cells utilising PQQ-dependent alcohol dehydrogenase (PQQ-ADH) and PQQ-dependent aldehyde dehydrogenase (PQQ-AldDH) In this paper, we describe the use of glycerol for a fuel in an enzymatic biofuel cell that utilizes a three-enzyme cascade on the anode that can accomplish the complete oxidation of glycerol The bioanode that was developed contained PQQ-ADH, PQQ-AldDH and oxalate oxidase immobilised within a tetrabutylammonium-modified Nafion membrane Our previous research has shown that glycerol is an effective fuel with the PQQ-ADH and PQQ-AldDH but still was unable to be fully oxidised With the addition of oxalate oxidase, these glycerol/air biofuel cells have yielded power densities of up to 132 mW cm–2, and have the ability to operate at high fuel concentrations The oxidation products were confirmed with 13C NMR and comprised mainly 13C-labelled carbonate and glycerate

172 citations


Journal ArticleDOI
TL;DR: In this article, home-prepared (HP) rutile TiO2 catalysts were used for the selective photocatalytic oxidation of 4methoxybenzyl alcohol to 4-methoxidebenzaldehyde in aqueous suspension.

158 citations


Journal ArticleDOI
TL;DR: In this paper, a mathematical model considering an autothermal reformer consisting of two distinct sections; a combustion section and a catalytic bed section was proposed and the results of the model were compared by ATR process published data.

115 citations


Journal ArticleDOI
TL;DR: In this paper, the effects of copper content, reaction temperature and O2 concentration on catalytic activity were investigated for steam reforming (SRM) and oxidative steam reforming of methanol (OSRM).

112 citations


Journal ArticleDOI
TL;DR: In this paper, the thermal partial oxidation process of methane was investigated numerically and experimentally using CHEMKIN tools to determine the practical operating conditions and the effects of air preheating temperature, thermal load and air ratio on the reforming process.

104 citations


Journal ArticleDOI
TL;DR: In this paper, an octahedral molecular sieves of the type K-OMS-2 (cryptomelane structure) with different morphologies and specific surface areas in the range of 20 −135m2−g−1 were prepared via synproportionation of KMnO4 and Mn2+ salts, either in acidic aqueous suspension (reflux method) or by a solid-state reaction, and via oxidation of MnSO4 either by K2Cr2O7 or by molecular oxygen in aaqueous solution.
Abstract: Manganese-based octahedral molecular sieves of the type K-OMS-2 (cryptomelane structure) with different morphologies and specific surface areas in the range of 20–135 m2 g−1 were prepared via synproportionation of KMnO4 and Mn2+ salts, either in acidic aqueous suspension (reflux method) or by a solid-state reaction, and via oxidation of MnSO4 either by K2Cr2O7 or by molecular oxygen in aqueous solution. For the reflux method, the influence of K+ cations for the formation of the OMS-2 structure was proven. When KMnO4 is replaced by Ba(MnO4)2, the anion in the Mn2+ salt exerts a strong influence on the synthesis product. All materials were characterized by elemental analysis (ICP-OES), XRD, nitrogen sorption, scanning electron microscopy and TGA. For the oxidation of benzyl alcohol with molecular oxygen in liquid toluene at 110 °C, the catalytic activity of the K-OMS-2 materials is directly correlated to their specific surface area ABET. Since ABET increases with decreasing average crystallite diameter, the catalytic conversion presumably occurs at the outer crystallite surface. These relations are independent of morphology or synthesis procedure. The K-OMS-2 materials are more active than crystalline manganese oxides (MnO, Mn2O3, Mn3O4, β-MnO2), but less active than amorphous MnO2. Regeneration of deactivated K-OMS-2 catalysts can be achieved by calcining at 300 °C in air, partly due to the reversible desorption of water.

104 citations


Journal ArticleDOI
TL;DR: In this article, the equilibrium compositions, the carbon deposition boundaries, and the electromotive forces for the direct utilization and partial oxidation of methanol and ethanol in SOFC as a function of the fuel utilization are obtained.

101 citations


Journal ArticleDOI
TL;DR: In this article, the performance of NiCu-based catalysts for partial Oxidation of Methane (CPOM) to synthesis gas was studied over supported NiCu based catalysts prepared by wet impregnation procedure.

97 citations


Journal ArticleDOI
TL;DR: In this paper, a two-temperature numerical model based on comprehensive heat transfer and chemical mechanisms is found to be in a good qualitatively agreement with experimental data, and the maximum hydrogen yield was close to 50% for all fuels, and carbon monoxide yield is close to 80%.

Journal ArticleDOI
TL;DR: In this article, the authors examined the electrooxidation of CO adsorbed on a polycrystalline Pt electrode in the potential region of hydrogen absorption by fast time-resolved surface-enhanced infrared absorption spectroscopy coupled to voltammetry or chronoamperometry.
Abstract: Electro-oxidation of CO adsorbed on a polycrystalline Pt electrode in the potential region of hydrogen absorption is examined by fast time-resolved surface-enhanced infrared absorption spectroscopy coupled to voltammetry or chronoamperometry. Oxidation dynamics at a weak preoxidation peak around 0.5 V (vs RHE) and the main oxidation peak around 0.7 V observed in stripping voltammetry are focused. IR spectra show that the shift of bridge-bonded CO to atop sites triggers the partial oxidation of CO adsorbed at atop sites to yield the preoxidation peak. It is also shown that CO on terraces becomes very mobile in the main oxidation region after some amount of CO being oxidized via a nucleation-and-growth mechanism and that terrace CO is oxidized faster than CO adsorbed at step edges. The result is interpreted in terms of a Langmuir−Hinshelwood type mechanism involving adsorbed CO and an oxygen-containing species (most likely OH) adsorbed at steps. The oxidation mechanism is essentially identical to that propo...

Journal ArticleDOI
TL;DR: In this article, the autothermal catalytic partial oxidation (CPO) of methane was performed at short contact times (∼8ms) over three Rh-based catalysts.

Journal ArticleDOI
TL;DR: In this article, NiO strongly interacted with support formed small nickel particles (about 4nm for NiSC which is abbreviation of Ni/SiO 2 prepared with Nickel citrate precursor) after reduction.

Journal ArticleDOI
TL;DR: In this paper, transition metal oxides (Ti, V, Mo, Cr, etc.) incorporated within the framework of zeolites were found to exhibit high and unique photocatalytic reactivity as single-site heterogeneous catalysts for various reactions such as the decomposition of NOx (NO, N 2 0) into N 2 and O 2, the reduction of CO 2 with H 2 0 to produce CH 4 and CH 3 0H, the preferential oxidation of CO in the presence of H 2 (PROX), the partial oxidation of various hydrocarbons with O

Journal ArticleDOI
TL;DR: In this paper, the X-ray absorption spectroscopy (XAS) was used to study the structure and distribution of the catalysts inside a catalytic quartz glass microreactor.

Journal ArticleDOI
TL;DR: Insight is provided into syngas and hydrogen production from methanol and ethanol partial oxidation, particularly highlighting catalytic chemistry.
Abstract: Hydrogen-powered fuel cell vehicles feature high energy efficiency and minor environmental impact. Liquid fuels are ideal hydrogen carriers, which can catalytically be converted into syngas or hydrogen to power vehicles. Among the potential liquid fuels, alcohols have several advantages. The hydrogen/carbon ratio is higher than that of other liquid hydrocarbons or oxygenates, especially in the case of methanol. In addition, alcohols can be derived from renewable biomass resources. Catalytic partial oxidation of methanol or ethanol offers immense potential for onboard hydrogen generation due to its rapid reaction rate and exothermic nature. These benefits stimulate a burgeoning research community in catalyst design, reaction engineering, and mechanistic investigation. The purpose of this Minireview is to provide insight into syngas and hydrogen production from methanol and ethanol partial oxidation, particularly highlighting catalytic chemistry.

Journal ArticleDOI
TL;DR: In this paper, the mesoporous SBA-15 support was used for hydrogen production from methanol by partial oxidation and steam reforming reactions and the physicico-chemical characteristics of the synthesized SBA15 support were confirmed by XRD, N 2 adsorption, SEM and TEM analyses.

Journal ArticleDOI
TL;DR: In this paper, the performance of molybdenum dioxide (MoO 2 ) as a catalyst for the partial oxidation of isooctane was investigated, and it was shown that an oxygen-to-carbon ratio (O/C) of 0.72 seems to stabilize the catalytic performance.
Abstract: The present investigation is focused on the performance of molybdenum dioxide (MoO 2 ) as a catalyst for the partial oxidation of isooctane. Metallic character and high oxygen mobility exhibited by this oxide appear to enhance its catalytic activity, which can be explained in terms of the Mars–van Krevelen mechanism. An oxygen-to-carbon ratio (O/C) of 0.72 seems to stabilize the catalytic performance, which could reach H 2 yields of 78% and carbon conversions of 100%, at 700 °C and 1 atm, after 20 h on stream. In addition, the catalyst was tested for sulfur tolerance using thiophene as model sulfur compound. Our findings indicate that the catalytic activity is barely affected even at sulfur concentrations as large as 500 ppm, after 7 h on stream. Finally, the catalyst performance was compared to that of a nickel catalyst using premium gasoline as fuel. MoO 2 displayed a stable performance whereas the Ni catalyst deactivated due to coke formation.

Journal ArticleDOI
TL;DR: The CPOx of glycerol is explored using a nebulizer to mix droplets with air at room temperature for reactive flash volatilization and results in a maximum in H(2) production at a steam/carbon ratio of 2:3 over a Rh-Ce catalyst.
Abstract: Glycerol, a commodity by-product of the biodiesel industry, has value as a fuel feedstock and chemical intermediate. It is also a simple prototype of sugars and carbohydrates. Through catalytic partial oxidation (CPOx), glycerol can be converted into syngas without the addition of process heat. We explored the CPOx of glycerol using a nebulizer to mix droplets with air at room temperature for reactive flash volatilization. Introducing this mixture over a noble-metal catalyst oxidizes the glycerol at temperatures over 600 degrees C in 30-90 ms. Rhodium catalysts produce equilibrium selectivity to syngas, while platinum catalysts produce mainly autothermal non-equilibrium products. The addition of water to the glycerol increases the selectivity to H(2) by the water gas shift reaction and reduces non-equilibrium products. However, water also quenches the reaction, resulting in a maximum in H(2) production at a steam/carbon ratio of 2:3 over a Rh-Ce catalyst. Glycerol without water produces a variety of chemicals over Pt, including methylglyoxal, hydroxyacetone, acetone, acrolein, acetaldehyde, and olefins.

Journal ArticleDOI
TL;DR: In this article, Ni catalysts supported on commercial α-Al 2 O 3 modified by addition of CeO 2 and/or ZrO 2 were prepared in the present work, and the principal objective was to evaluate the behavior of these systems and the support effect on the stability.

Journal ArticleDOI
TL;DR: A series of Nb-containing hematites, Fe2−xNbxO3 (%Nb = 0.00, 1.49, 5.00 and 9.24) was prepared using the conventional co-precipitation method as mentioned in this paper.
Abstract: A series of Nb-containing hematites, Fe2−xNbxO3 (%Nb = 0.00, 1.49, 5.00 and 9.24) was prepared using the conventional co-precipitation method. Mossbauer and temperature-programmed reduction (TPR) measurements suggested the formation of the crystalline phase with partial substitution of Fe3+ by Nb5+ in the structure. N2 adsorption/desorption revealed that the presence of Nb has a remarkable effect on the textural properties of the material with an increase in the BET surface area. The reactivity of Fe2−xNbxO3 was investigated using the oxidation of the methylene blue dye used as a model pollutant. The obtained results showed that the presence of Nb seems not to act directly promoting the H2O2 decomposition, but improving the dye oxidation. The analysis using the ESI-MS technique showed partial oxidation observed through different intermediates before the mineralization. This suggests the use of Nb-doped hematite as an efficient catalyst in degradation reactions in the presence of H2O2 or ultraviolet light.

Journal ArticleDOI
TL;DR: In this article, the thermal behavior of Rh-coated honeycomb monoliths was studied under representative operating conditions, at steady state and during light-off, and the feasibility of small-scale production of syngas via CH4 catalytic partial oxidation relies on thermal management of the short contact time reactor.
Abstract: The present study consists of an experimental and theoretical study of the performance of Rh-coated honeycomb monoliths for methane partial oxidation. The thermal behavior of Rh-coated honeycomb monoliths was studied under representative operating conditions, at steady state and during light-off. Model analysis (based on a dynamic heterogeneous reactor model that incorporates a kinetic scheme of the process independently developed, and well-assessed correlations for heat and mass transfer) provided a key for interpreting the observed effects. The comprehension of how transport phenomena and surface kinetics affect the reactor behavior leads to the conclusion that the feasibility of small-scale production of syngas via CH4 catalytic partial oxidation relies on thermal management of the short contact time reactor and not the obtainment of high syngas yields (which is not a challenging task). Severe operating conditions (and high surface temperatures) can deplete the catalyst activity and cause unstable reac...

Journal ArticleDOI
TL;DR: In this paper, a supported Ni catalysts with a core/shell structure at the multibubble sonoluminescence (MBSL) condition and their catalytic tests for methane decomposition by partial oxidation were performed.

Journal ArticleDOI
TL;DR: Rutile exhibited the highest yield to p-anisaldehyde at a rate of the same order of magnitude of that showed by the other samples, which have been characterised by an in situ ATR-FTIR investigation carried out in conditions simulating the photoreaction ones.
Abstract: TiO2 catalysts of anatase, rutile and brookite phase were prepared at low temperature and tested for carrying out the photocatalytic partial oxidation of 4-methoxybenzyl alcohol to 4-methoxybenzaldehyde (p-anisaldehyde) in organic-free water suspensions. Traces of 4-methoxybenzoic acid and open-ring products were the only by-products present, CO2 being the other main oxidation product. Rutile exhibited the highest yield to p-anisaldehyde (62% mol) at a rate of the same order of magnitude of that showed by the other samples. Commercial rutile and anatase photocatalysts were also used for the sake of comparison. The samples have been characterised by an in situ ATR-FTIR investigation carried out in conditions simulating the photoreaction ones.

Journal ArticleDOI
TL;DR: In this article, a hydrocarbon-selective catalytic reduction (HC-SCR) silver-alumina monolith catalyst has been prepared and tested for NO x emissions control in a diesel engine.

Journal ArticleDOI
TL;DR: In this article, a spatiotemporal operando X-ray absorption study of a highly dynamic process, the ignition of the noble metal catalyzed partial oxidation of methane, is presented, which combines temperature profiling by IR-thermography and catalytic activity measurements by online mass spectrometry gives insight into the first stages of the reaction toward hydrogen and carbon monoxide.
Abstract: We present a spatiotemporal operando X-ray absorption study of a highly dynamic process, the ignition of the noble metal catalyzed partial oxidation of methane. Evolvement and propagation of the platinum component’s structural changes are investigated with a high-speed X-ray camera, which in combination with temperature profiling by IR-thermography and catalytic activity measurements by online mass spectrometry gives insight into the first stages of the ignition of the reaction toward hydrogen and carbon monoxide.

Journal ArticleDOI
01 Feb 2009-Energy
TL;DR: In this paper, a gliding arc reformer was proposed to produce hydrogen-rich gas from methane, which has two reactors including a plasma reactor and a catalytic effect and CO 2 input concentration.

Journal ArticleDOI
Xueqin Wang1, Junping Wu1, Mingwei Zhao1, Yufen Lv1, Guiying Li1, Changwei Hu1 
TL;DR: In this article, the partial oxidation of toluene by hydrogen peroxide with catalytic amount of bis (acetylacetonato) oxovanadium (VO(acac)2) in acetic acid is studied in detail.
Abstract: The partial oxidation of toluene by hydrogen peroxide with catalytic amount of bis (acetylacetonato) oxovanadium (VO(acac)2) in acetic acid is studied in detail. Benzaldehyde is found to be the main product in the reaction, and V51NMR and ESI-MS are used to detect the possible intermediate species. The effect of reaction parameters, such as the amounts of catalyst and hydrogen peroxide used, the reaction temperature, and reaction time on the reaction are investigated. The mechanism of toluene partial oxidation is also studied, and the hydroxyl radical is found to be the key active species. The solvent acetic acid coordinates with vanadium atom, and the toluene partial oxidation passes through cage reaction to form the C6H5CH·(OOH) radical, which promptly decomposes to benzaldehyde and hydroxyl radical. C6H6CH2OOCH2C6H6 is also found to be one possible intermediate.

Journal ArticleDOI
TL;DR: Haynes et al. as mentioned in this paper showed that the presence of organosulfur compounds hinders the catalytic partial oxidation (CPOX) of logistic fuels into a H 2 -rich gas stream for fuel cells.