NO Reduction Reaction Research Articles

Reduction of NO with Fe(ii) and subsequent regeneration of Fe(ii) in a fuel cell

We report complete reduction reaction of NO into N2 by oxidizing Fe2+ into Fe3+. To regenerate Fe2+ as a NO absorbent from Fe3+, the H2–Fe3+ fuel cell supplied by Fe3+-containing solution at the cathode is utilized producing maximum power density of 110 mW cm−2 at 70 °C.

The investigation of SCR reaction on sulfated CaO

AbstractThe catalytic activity of sulfated CaO in the selective catalytic reduction (SCR) reaction of NO with NH3 in the presence of O2 was investigated. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), Brunauer–Emmett–Teller (BET), SEM, XRD, NH3‐TPD (temperature programmed desorption), and NO‐TPD were used to characterize the catalyst of sulfated CaO and analytical grade CaSO4. The BET results indicated that the surface area decreased as the sulfation extent increased due to pore plug. SEM analysis revealed the surface morphology of the sulfated CaO with different sulfation extent. XRD results suggested that the sulfated CaO was hexagonal CaSO4. NH3‐TPD and NO‐TPD experiments indicated that NH3 was more likely to be absorbed on the sulfated CaO than NO, and as the sulfation extent increased, the acid sites reduced because of the decreasing surface area, but the acid strength of surface acidity increased. Based on the characterization and SCR reaction results, NH3 adsorption on CaO and CaSO4, and then reaction with O2 or NO would be the possible reaction route on sulfated CaO. Copyright © 2010 Curtin University of Technology and John Wiley & Sons, Ltd.

CO Oxidation and NO Reduction on a MgO(100) Supported Pd Cluster: A Quantum Chemical Molecular Dynamics Study

Dynamics of the CO oxidation NO reduction reaction on thin MgO (100) supported Pd clusters has been studied by quantum chemical molecular dynamics (QCMD). Chemical changes, change of adsorption states, and structural changes were investigated. We observed that CO adsorption occurs molecularly, whereas NO adsorption occurs first molecularly on the Pd cluster, but it is then dissociatively adsorbed on Pd cluster after interacting with CO. Oxygen atoms resulting from the NO dissociation react with adsorbed CO and form CO2 that desorbs from the Pd cluster, whereas the remaining N atom diffuses in the lattice of the Pd cluster. NO dissociation has been found to be the key step for this reaction. Furthermore, from the molecular dynamics and electronic structure calculations, we have identified a number of consequences for the interpretation and modeling of diffusion experiments demonstrating the coverage. As far we know, this is the first QCMD based simulation of the dynamics of CO oxidation, NO reduction, and ...

Research on Plasma Chemistry Reactions in C3H6/NO/O2/N2 Mixture Gases

A DBD-type (dielectric barrier discharge) NTP (non-thermal plasma) reactor was designed and an experimental system was established, in order to study the mechanism of plasma chemistry reactions in a gas mixture of C3H6/NO/O2/N2. This paper is focused on a. the effects of the initial concentrations of both NO and O2 upon NO conversion rate and the variations of NOx and O3 concentrations versus SED (specific energy density) when mixed gases of NO/O2/N2 passed the NTP reactor; b. the effects of the initial concentration of C3H6 upon NO oxidation and reduction reactions in mixed gases of NO/N2/C3H6 and NO/N2/O2/C3H6. The conclusions drawn are as follows. a. When the mixed gases of NO/O2/N2 passed the NTP reactor, NO was simultaneously involved in oxidation and reduction reactions with the former dominant and NO2 concentration increased at the NTP reactor outlet. The NO conversion rate decreased with the increase of the initial concentration of NO and O2, the O3 concentration firstly increased and then decreased with the increase in SED value. b. NO reduction reaction was very weak and energy consumption was very high in a mixed gases of NO/N2. However, when C3H6 was added, the NO conversion rate was significantly increased. When C3H6 was added to the mixed gases of NO/O2/N2, the NO conversion rate was significantly increased and the energy consumption was considerably reduced.

ChemInform Abstract: The Surface Science Approach Toward Understanding Automotive Exhaust Conversion Catalysis at the Atomic Level

This review focuses on the reactions and catalysts used for control of emissions of exhaust gases for gasoline-fueled automobiles with emphasis on fundamental understanding of the surface processes. Attention is paid to three-way catalysts, which simultaneously enhance the conversion of CO, hydrocarbons, and nitrogen oxides. The mechanisms of the CO oxidation and nitrogen oxide reactions, the specific differences in behavior of Pt, Pd, and Rh, the effect of alloy formation, and the role of ceria used as additive in three-way catalysts are discussed. Results of surface science studies are compared with results reported for supported catalysts. For CO oxidation, there is excellent agreement between results obtained for single crystal surfaces and supported catalysts. The kinetics of the reactions on pure metals can be understood on the basis of the kinetics parameters obtained from single-crystal studies. For the NO reduction reactions, there is qualitative agreement between results obtained with single-crystal and supported catalysts. The major effects of alloy formation can be understood on the basis of the surface composition.

Mean-field study of the synergic effect of the CO–NO reaction on a heterogeneous substrate of interconnected sectors

A mean-field theory study is made of the behaviour of a kinetic model of the reduction reaction of NO by CO catalyzed by a surface with simple heterogeneity consisting of two interconnected sectors that differ in their NO dissociation activation energy. A synergistic effect is manifested in the activity, apparent activation energy, and reaction order of the system. This situation, analogous to that observed in the literature in the case of a heterogeneous catalytic particle, is used in the paper to analyze a real case of a bimetallic catalyst.

Reduction Behaviors of Nitric Oxides on Copper-decorated Mesoporous Molecular Sieves

‡§ In this study, NO reduction behaviors of copper-loaded mesoporous molecular sieves (Cu/MCM-41) have been investigated. The Cu loading on MCM-41 surfaces was accomplished by a chemical reduction method with different Cu contents (5, 10, 20, and 40%). N2/77 K adsorption isotherm characteristics, including the specific surface area and pore volume, were studied by BET’s equation. NO reduction behaviors were confirmed by a gas chromatography. From the experimental results, the Cu loading amount on MCM-41 led to the increase of NO reduction efficiency in spite of decreasing the specific surface area of catalysts. This result indicates that highly ordered porous structure in the MCM-41 and the presence of active metal particles lead the synergistical NO reduction reactions due to the increase in adsorption energy of MCM-41 surfaces by the Cu particles.

NO Reduction by CO Catalyzed with Au/TiO2 in Oxygen-rich Condition

AbstractGold nanoparticles supported on titania catalysts with different Au loadings were prepared and evaluated in the reaction of NO reduction by CO in an oxygen rich condition. The crystalline structures of the Au/TiO2 materials were refined with Rietveld method. TiO2 support chiefly contains anatase phase, having a crystalline size ranged from 5 to 15 nm. Au particles have an average crystal size approximately 2-5 nm as Au concentration less 3 wt %. In the reaction of NO + CO + O2, the Au/TiO2catalysts show a selectivity to 100 % N2, neither NO2 nor N2O was yielded in the reaction temperature between 25 and 400 °C, which strongly indicates that Au/TiO2catalysts are much superior to the other catalysts like Pt/TiO2 catalysts on which N2O was usually produced in the reaction temperature below 200 °C and NO2 was produced in the reaction temperature above 300 °C under a similar reaction condition.

2P110 亜鉛置換型NORを利用したNO還元反応の解析(ヘム蛋白質,第48回日本生物物理学会年会)

2P110 亜鉛置換型NORを利用したNO還元反応の解析(ヘム蛋白質,第48回日本生物物理学会年会)

Density-functional theory calculation on the nitrogen oxide reduction reaction with carbon monoxide on a titanium dioxide nanocluster

The density functional theory was used for simulation of the NO reduction reaction with carbon monoxide on a reduced Ti8O15 nanocluster. The reaction proceeds on oxygen vacancies formed via the removal of terminal or bridging O atoms. In the case of adsorption of two NO molecules of such sites, a stable adsorption complex with the bidentate ligand ‥ONNO is produced. When a CO molecule approaches one of the O atoms of this cycle, the following exothermic reaction yielding N2 and CO2 adsorbed on the Ti8O16 cluster takes place: 2NO+ CO + Ti8O15 → N2+ Ti8O16 · CO2. The proposed model of the reaction agrees well with experimental data.

Study of low-temperature selective catalytic reduction of NO by ammonia over carbon-nanotube-supported vanadium

In this article, low-temperature selective catalytic reduction (SCR) reaction of NO on carbon nanotube-supported vanadium (V 2O 5/CNT) catalysts was carried out. When compared with activated carbon as a support catalyst, carbon nanotubes with low load of V 2O 5 show excellent catalytic activity than that of activated carbon, and the catalytic activity of V 2O 5/CNT catalysts increases markedly in the presence of SO 2. The transient reaction experiment shows that the reaction of V 2O 5/CNT catalyst for low-temperature SCR of NO follows the mechanism of Eley–Rideal, namely by the reaction between the adsorbed NH 3 and NO in the gaseous or a weakly adsorbed state.

Thermally Stable CeO2–ZrO2–La2O3 Ternary Oxides Prepared by Deposition–Precipitation as Support of Rh Catalyst for Catalytic Reduction of NO by CO

The work mainly reported that CeO2–ZrO2–La2O3 mixed oxide was synthesized by deposition–precipitation method and used as support of Rh catalyst. The physicochemical properties of the resultant CeO2–ZrO2–La2O3 mixed oxides were characterized by X-ray powder diffraction (XRD), Vis-Raman, N2 adsorption, transmission electron microscopy, temperature-programmed reduction, and oxygen storage capacity and the catalytic activities of Rh-loaded CeO2–ZrO2–La2O3 catalysts were evaluated by the reduction reaction of NO by CO. The combination of XRD and Raman results demonstrates that the resultant CeO2–ZrO2–La2O3 mixed oxides have a mixed phase comprised mainly of m-phase, c-phase, and t-phase. Compared with the counterpart prepared by co-precipitation method, Rh-loaded CeO2–ZrO2–La2O3 catalysts prepared by the deposition–precipitation method exhibited higher heat tolerance and better catalytic activity for the reduction of NO by CO as well as more uniform and discrete nanoparticles. The structural and textural characteristics caused by synthesis technique and the high dispersity of Rh on the materials are dominant contributors to the improvement of catalytic performance.

A new preparation method of Au/ferric oxide catalyst for low temperature CO oxidation

A new preparation method of Au/α-Fe 2O 3 catalyst for CO oxidation reaction was proposed in this paper. The method includes only a simple modification of the conventional coprecipitation method, adding HAuCl 4 solution after the growth of iron hydroxide grain to a certain size, but significantly influenced the catalytic activity in the reaction. In the characterization study, XRD (X-ray diffractometer) analysis, TEM (transmission electron microscope) observation, and N 2 adsorption measurement showed similar results among the samples calcined at the same temperature, but the effect of the preparation method appeared in the CO adsorption measurement among the samples calcined at 200 °C. Catalysts having high CO adsorption ability also performed well in CO oxidation tests. The CO adsorption and oxidation studies indicated that the proposed preparation method results in stable and effective loading of Au, compared to the conventional coprecipitation method. In the CO oxidation test, the catalyst prepared by the proposed mixing scheme achieved complete CO conversion for more than 3000 h at 25 °C, space velocity 100,000 h −1, and 500 ppm CO. The selectivity for the CO oxidation was confirmed using reformed gas containing excess H 2. In addition, the NO reduction reaction was favored over CO oxidation by the catalyst. Thus, we were able to load Au on the α-Fe 2O 3 effectively and demonstrate its potential as an environmental catalyst.

Experimental Study of the Effects of CO2on the Noncatalytic Reduction Reaction of NO by Carbonaceous Materials

In a fixed bed reactor with a quartz tube, the effects of the concentration of CO2 in the feed gas on the uncatalyzed reaction between soot produced in a natural gas diffusion flame and NO were investigated. They were compared with CO2 effects on reactions involving candle soot and bituminous coal char. The presence of CO2 in the feed gas exerted no influence on the reaction of NO with natural gas soot. However, it did result in a lower initial temperature in the reaction of candle soot or coal char with NO, and separated the whole initial reaction process into two stages. At higher CO2 concentrations, more NO reduction occurred in the reaction with candle soot or coal char during the initial reaction process. However, no dramatic changes in the amount of NO reduction were observed for natural gas soot. The addition of CO2 seemed to have no effect on the apparent activation energy of the NO−natural gas soot reaction, while a lowering of the apparent activation energy was observed in the reaction of NO with candle soot or coal char as the CO2 concentration increased. The abundant C(O) complexes formed during sample gasification by CO2 were assumed to play an important role in the enhancement of the reaction.

Effect of surface heterogeneity steps-terraces in a mean field model for the catalytic CO-NO reaction

Based on a model proposed by Olsson et al. (Surf. Sci. 2003, 529, 338), a study is made through a mean field scheme of the effect of steps-terraces superficial heterogeneity, whose energy differences have been determined recently by means of density functional theory (DFT), in the catalytic reduction reaction of NO by CO over palladium. Several aspects are seen, such as the relation between the activities produced in both sectors of the surface as a function of temperature and the energy difference between them, the activity and coverage versus the temperature and the gas phase concentration curves, and the effect on these variables of the activation energy values on the steps of some stages of the kinetic mechanism. The system shows a reaction order with respect to CO and NO that changes sign between low and high temperatures, from negative to positive in the case of CO and the opposite for NO.

Óxidos do tipo perovskita para reação de redução de no com CO

In this work, the perovskite-type oxides LaNiO3, LaMnO3, La0,7Sr0,3NiO3 and La0,7Sr0,3MnO3 were prepared by co-precipitation and tested in the NO reduction with CO at 400 and 500 oC for 10 h. The catalysts were characterized by X-ray diffraction, temperature programmed reduction with hydrogen, nitrogen adsorption and chemical analysis. The nonstoichiometric oxygen was quantified by temperature programmed reduction, and the catalytic tests showed that the La0,7Sr0,3MnO3 catalyst presented the higher performance for the reduction reaction of NO with CO. The partial substitution of lanthanum by strontium increased the NO conversion and the N2 yield.

Monte Carlo Simulations of a Recent Kinetics Mechanism for the Reduction Reaction of NO by CO on Percolation Clusters

Abstract The behavior of a recent kinetics mechanism for the reduction reaction of NO by CO on the surface of a series of percolation clusters is studied by means of Monte Carlo simulations using experimental rate constant values from the literature. The structural sensitivity of the reaction is observed through the production curves and phase diagrams. The kinetics phase transitions and the relation between production and the mean number of nearest neighbors of the cluster’s active site, the temperature and the pressure of the gas-phase components are analyzed.

Monte Carlo study of the influence of the structural heterogeneity of the surface in the CO–NO reaction on Pd and its relation with experimental data

The reduction reaction of NO by CO over Pd is studied by means of a Monte Carlo simulation. A reaction mechanism similar to that established previously in the literature for Rh and a set of recently published kinetics parameters for Pd determined from experimental work are assumed. The heterogeneous effects of the catalytic substrate are analyzed by simulating various surfaces: a uniform square and hexagonal lattice, the incipient percolation cluster (IPC) fractal, and a lattice formed by a cluster distribution supported on a deterministic fractal. The results interpret reasonably the experimental data published recently in the case of crystals and supported catalysts.

Time Decay of the Activity of the Reduction Reaction of NO by CO on a Pd/Al2O3 Catalyst

An experimental study is made of the time decay of activity of the CO–NO reaction on a Pd/Al2O3 looking at the effect on reaction order and apparent activation energy. The optimum kinetics parameters fitting the steady state data at moderate pressures are determined. The time decay curves are analyzed through various catalyst deactivation models.

Electrocatalytic reduction of [formula omitted] in a neutral solution on an electrodeposited film of amorphous Pd 33Ni 60P 7 alloy

An amorphous Pd 33Ni 60P 7 alloy was prepared by electrodeposition in a bath containing 0.02 mol L −1 PdCl 2, 0.04 mol L −1 NiSO 4 · 6H 2O, 0.24 mol L −1 H 3PO 3, 0.32 mol L −1 H 3BO 3, and 0.08 mol L −1 ethylenediamine (C 2H 8N 2), under conditions of pH 4.0, 50 °C and 25 mA cm −2. The amorphous structure of the Pd 33Ni 60P 7 deposit was confirmed with X-ray diffraction (XRD) analysis. The activity of electrocatalytic reduction of nitrate on the amorphous Pd 33Ni 60P 7 deposit was studied with cyclic voltammetric (CV) technique in a neutral 0.1 mol L −1 KClO 4 solution with or without KNO 3. The results indicate that the Pd 33Ni 60P 7 alloy deposit exhibits a higher activity for the reduction of the nitrate in comparison with the electrodeposited films of Pd, Ni and Pd–Ni, which could be owing to its amorphous structure. The reduction reaction of NO 3 - on the electrode is a totally irreversible process.