NO Oxidation Rate Research Articles

The promotional effects of cerium on the catalytic properties of Al2O3-supported MnFeOx for NO oxidation and fast SCR reaction

To reveal the cooperative effects of cerium with manganese and iron on the catalytic oxidation of NO to NO2 and the catalytic activity in the fast selective catalytic reduction (SCR) reaction, Ce–MnFeOx/Al2O3 catalysts were prepared with different amounts of cerium doping. The results showed that the oxidation rate of NO to NO2 achieved by MnFeOx/Al2O3 was obviously improved with cerium doping. The highest catalytic activity, corresponding to NOx conversion >95.5% within the range of 100–350 °C and NO oxidation rate of 55.1% at 350 °C, was obtained when using Ce1.0–MnFeOx/Al2O3 (Ce:Fe:Mn = 1:2:16), Furthermore, according to characterization by scanning electron microscopy (SEM), X-ray diffraction (XRD), H2-temperature-programmed reduction (TPR), NH3-temperature-programmed desorption (TPD), NO-TPD, and X-ray photoelectron spectroscopy (XPS) techniques, the active element dispersion and combination of iron and manganese were both enhanced with cerium doping, while the metal oxide crystallinity was reduced. Cerium doping improved the Mn4+/(Mn2+ + Mn3+ + Mn4+) and Fe3+/(Fe2+ + Fe3+) ratios, while increasing the amounts of lattice oxygen and oxygen vacancies, thereby promoting the oxidation rate of NO to NO2 and ultimately facilitating the fast SCR reaction. However, excess cerium doping led to crystallization of ceria. This study revealed that Ce1.0–MnFeOx/Al2O3 has potential for application as an excellent catalyst with efficient catalytic activity in NO preoxidation and the fast SCR reaction.

Shape-controlled synthesis of MnOx–CeO2 oxides and their catalytic performance in NO oxidation

MnOx–CeO2 nanocubes and nanorods with the pure fluorite-type ceria crystalline structure have been synthesized, in order to investigate the effect of catalysts shape in NO oxidation. The results indicated that both of the nanomaterials growing from Ce(OH)3 nanorods nuclei, and higher hydrothermal temperature and alkali concentration facilitated the conversion of nanorods to nanocubes. During the synthesis process, manganese ions could incorporate into the ceria lattice without affecting its crystalline structure and growth mechanism. The morphology of this binary oxide determines NO oxidation rate, while the specific reaction rate on the reactive {100} planes was two times higher than that on the {111} planes, due to co-effect of the valence state of manganese ions, surface energy and the ratio of surface lattice oxygen species. The results could provide guidance for understanding of the importance of catalyst design in NO oxidation.

Gas-phase oxidation of NO at high pressure relevant to sour gas compression purification process for oxy-fuel combustion flue gas

Abstract The removal of NO from oxy-fuel combustion is typically incorporated in sour gas compression purification process. This process involves the oxidation of NO to NO2 at a high pressure of 1–3 MPa, followed by absorption of NO2 by water. In this pressure range, the NO conversion rates calculated using the existing kinetic constants are often higher than those obtained experimentally. This study aimed to achieve the regression of kinetic parameters of NO oxidation based on the existing experimental results and theoretical models. Based on three existing NO oxidation mechanisms, first, the expressions for NO conversion against residence time were derived. By minimizing the mean-square errors of NO conversion ratio, the optimum kinetic rate constants were obtained. Without considering the reverse reaction for NO oxidation, similar mean-square errors for NO conversion ratio were calculated. Considering the reverse reaction for NO oxidation based on the termolecular reaction mechanism, the minimum mean-square error for NO conversion ratio was obtained. Thus, the optimum NO oxidation rate in the pressure range 0.1–3 MPa can be expressed as follows: − d NO / d t = d NO 2 / d t = 0.0026 NO 2 O 2 − 0.0034 NO 2 2 Detailed elementary reactions for N2/NO/NO2/O2 system were established to simulate the NO oxidation rate. A sensitivity analysis showed that the critical elementary reaction is 2NO + O2 ⇌ 2NO2. However, the simulated NO conversions at a high pressure of 10–30 bar are still higher than the experimental values and similar to those obtained from the models without considering the reverse reaction for NO oxidation.

Optimization of NO oxidation by H2O2 thermal decomposition at moderate temperatures.

H2O2 was adopted to oxidize NO in simulated flue gas at 100–500°C. The effects of the H2O2 evaporation conditions, gas temperature, initial NO concentration, H2O2 concentration, and H2O2:NO molar ratio on the oxidation efficiency of NO were investigated. The reason for the narrow NO oxidation temperature range near 500°C was determined. The NO oxidation products were analyzed. The removal of NOx using NaOH solution at a moderate oxidation ratio was studied. It was proven that rapid evaporation of the H2O2 solution was critical to increase the NO oxidation efficiency and broaden the oxidation temperature range. the NO oxidation efficiency was above 50% at 300–500°C by contacting the outlet of the syringe needle and the stainless-steel gas pipe together to spread H2O2 solution into a thin film on the surface of the stainless-steel gas pipe, which greatly accelerated the evaporation of H2O2. The NO oxidation efficiency and the NO oxidation rate increased with increasing initial NO concentration. This method was more effective for the oxidation of NO at high concentrations. H2O2 solution with a concentration higher than 15% was more efficient in oxidizing NO. High temperatures decreased the influence of the H2O2 concentration on the NO oxidation efficiency. The oxidation efficiency of NO increased with an increase in the H2O2:NO molar ratio, but the ratio of H2O2 to oxidized NO decreased. Over 80% of the NO oxidation product was NO2, which indicated that the oxidation ratio of NO did not need to be very high. An 86.7% NO removal efficiency was obtained at an oxidation ratio of only 53.8% when combined with alkali absorption.

Role of cerium in improving NO reduction with NH3 over Mn–Ce/ASC catalyst in low-temperature flue gas

Mn–Ce mixed oxide was loaded onto activated semi-coke (ASC) via impregnation method and the low temperature selective catalytic reduction (SCR) of NO with NH3 was investigated. The NO conversion and NO oxidation rates were both influenced by the ratios of Ce/(Mn+Ce), and Mn–Ce(0.3)/ASC with loading 5% (mass ratio) Mn–Ce oxides performed the highest catalytic conversion rate of 96.6% and NO oxidation rate of 18.4% at 250°C and GHSV=6000h−1. The changes of physical properties, microstructure, functional groups, crystal structure, surface atomic state, redox property and acid strength for the catalysts were characterized by BET, SEM, FT-IR, XRD, XPS, H2-TPR and NH3-TPD. The results showed that surface functional groups were increased after nitric acid treatment and abundant oxygen groups were observed on semi-coke surface, which were considered to be beneficial for the gas adsorption. Ce doping could raise the Mn4+/Mnx+ rate which played a vital role in catalytic reaction, enhancing the amount of weak and strong acid sites, increasing oxygen vacancies and accelerating the molecular oxygen turning into reactive oxygen species, which could enhance the NO oxidation activity thus contributed to the denitration efficiency.

Experimental assessment of the bifunctional NH3-SCR pathway and the structural and acid-base properties of WO3 dispersed on CeO2 catalysts

A bifunctional pathway for selective catalytic reduction (SCR) with NH3 was established using a mixture of WO3/ZrO2 possessing strong acidity and CeO2 possessing moderate redox activity. The physical mixture (tight contact) of WO3/ZrO2 (4.2 W/nm2) and CeO2 provided enhanced SCR reactivity but did not improve the redox property assessed by NO oxidation. No improvement of the SCR conversion, however, was observed for mixtures of individual pellets (loose contact), suggesting the requirement of submicrometer-level proximity of the acidic sites to the redox centers. WO3/CeO2 (5.3 W/nm2) with intermediate acidic strength had higher SCR and NO oxidation rates than the aforementioned physical mixture of WO3/ZrO2 and CeO2. The weakly basic sites (OH species) on CeO2 were replaced stoichiometrically with strongly acidic sites on the WO3 domains along with an increase in the W density (0–24.4 W/nm2), and monoclinic WO3 crystallites then formed at approximately 10 W/nm2. The dispersed WO3 was in a distorted octahedral environment in all WO3/CeO2 samples. The intrinsic SCR reactivity was controlled by only the W surface density; the SCR rate (per surface area) increased within the polytungstate submonolayer region (<5–10 W/nm2) and then nearly reached a plateau. The NO oxidation rate also increased with an increase of the W density in a similar trend to the SCR rate, which is indicative of the formation of redox-active centers, rendering the synergetic enhancement of SCR reactivity. These findings and conclusions reached here provide useful guidance for new bifunctional strategies to achieve practical SCR performance.

NO oxidation on Fe- and Cu-zeolites mixed with BaO/Al2O3: Free oxidation regime and relevance for the NH3-SCR chemistry at low temperature

Oxidative activation of NO is commonly regarded as a key step in the low-temperature mechanism of Standard SCR on metal-promoted zeolite catalysts for NH3-SCR of NOx. In the present work, we systematically investigate the dynamics of NO oxidation as well as the reactivity of NO+NO2 with adsorbed and gas-phase NH3 on Fe-ZSM-5 and Cu-CHA catalysts, using chemical trapping techniques. The approach is based on physically mixing the metal promoted zeolite catalyst with a NOx trap material, i.e. BaO/Al2O3. We show that in these combined systems, as long as NOx storage sites are available, the initial rate of NO oxidative activation is substantially higher than over the metal promoted zeolite alone, as measured in conventional steady-state activity tests for NO oxidation to NO2. Similar dynamics with enhanced initial NO conversions are observed also in the case of metal promoted zeolite catalysts with preadsorbed NH3, suggesting a close analogy between the role of BaO in the chemical trapping runs and the role of adsorbed NH3 in Standard SCR conditions, both species removing effectively the NO oxidation products from the gas phase and therefore preventing their inhibitory action. These novel findings are relevant to estimate correctly the intrinsic kinetics of the NO oxidative activation over metal-promoted zeolite SCR catalysts, and may help to explain the so far unresolved divergence between the rate of NO oxidation to NO2 and the rate of the Standard SCR reaction. We show, in fact, that the rate of uninhibited NO oxidation is able to sustain the Standard SCR activity over both Fe- and Cu-zeolite catalysts.

Promotional effect of iron modification on the catalytic properties of Mn-Fe/ZSM-5 catalysts in the Fast SCR reaction

A series of Mn-Fe/ZSM-5 catalysts with varying amounts of iron doping were prepared via the impregnation method and their catalytic activities in Fast SCR and NO oxidation evaluated. It was found that NOx (NO+NO2) conversion using the iron-modified catalysts was obviously improved, probably due to the interaction between manganese and iron. Mn-Fe/ZSM-5 with a molar ratio of Fe/Mn=0.49 exhibited the highest activity, achieving >96.15% NOx conversion at 100°C and stabilizing at about 100% conversion at between 150 and 250°C. The properties of the catalysts were characterized using ICP, BET, XRD, H2-TPR, NH3-TPD and XPS techniques. XRD analysis revealed that the coexistence of manganese and iron oxides promoted the dispersion of active components and lowered the crystallinity, while the XPS results showed that iron doping increased the ratio of Mn4+, increasing levels of oxygen vacancy and lattice oxygen, thereby facilitating the oxidation of NO to NO2 and ultimately accelerating the Fast SCR process. However, excessive iron loading can lead to the agglomeration of active components. Furthermore, Mn-Fe(0.490)/ZSM-5 also exhibited superior performance in terms of NO oxidation, with the maximum NO oxidation rate of 55.88% recorded at 300°C, indicating the former's potential as a pre-oxidation catalyst for the Fast SCR reaction.

Basic rules of NO oxidation by Fe2+/H2O2/AA directional decomposition system

AbstractBasic rules of NO oxidation by a Fe2+/H2O2/AA directional decomposition system were researched based on the technical background of flue gas NOx removal. Effects of gas‐liquid interfacial area, main gas, and solution parameters on NO oxidation efficiency (η) were analyzed. The results showed that adequate contact area was the precondition for high η by a Fe2+/H2O2/AA system. η decreased with the increase in NO concentration, which illustrated that this method would be efficient in oxidizing NO at a low concentration. η tended to decrease linearly with the growth in gas flow, however, the NO oxidation rate (v) rose with the increase in NO concentration and gas flow. η increased with the initial concentrations of H2O2 and Fe2+, but the amplitude decreased. Controlling the initial concentrations of H2O2 and Fe2+ to achieve reasonable synergies between generation rate and consumption rate of ·OH could weaken the invalid consumption of reactants. η increased with the increase in temperature in the range 30–60 °C, but it nearly did not change with temperature after 60 °C. This oxidation technology and the traditional wet flue gas desulphurization technology exhibited temperature synergy. Under typical pH of wet desulphurization, η and H2O2 consumption rate did not change obviously.

Facile synthesis of double cone-shaped Ag4V2O7/BiVO4 nanocomposites with enhanced visible light photocatalytic activity for environmental purification

Abstract Ag4V2O7/BiVO4 photocatalysts with double cone-shaped nanostructure were successfully synthesized by a facile sodium polyphosphate-assisted hydrothermal method. The results demonstrate that coupling Ag4V2O7 with BiVO4 can promote the separation of photoinduced charge carriers and enhance the photon absorption efficiency. Experimental results indicate that Ag4V2O7/BiVO4 composites exhibit the enhanced photocatalystic activity for degradation of methylene blue (MB) and oxidation of NO in high concentrate (1600 ppb) compared to the pure BiVO4 under visible light irradiation (λ > 420 nm). The composite with 0.08 mol% Ag4V2O7 has the highest photocatalytic activity. MB degradation rate can reach 98.48% in 1 h and NO oxidation rate can reach 52.83% in 0.5 h on 0.08-Ag4V2O7/BiVO4, which are about 2.90 and 3.11 times higher than that of pure BiVO4 respectively. The excellent activity can be attributed to the efficient charge transfer between Ag4V2O7 and BiVO4, and active species h+ and O2− play important roles during MB degradation and NO oxidation. In addition, this composite exhibits favorable stability during the cycling experiment, suggesting it may be a promising visible light active photocatalyst for environmental applications.

Impact of PtOx formation in diesel oxidation catalyst on NO2 yield during driving cycles

Operation of a platinum-based diesel oxidation catalyst under lean conditions leads to the partial transformation of metallic Pt sites into platinum oxides (PtOx) with considerably lower NO oxidation rate. The varying NO2 yield depending on PtOx coverage significantly influences the performance of other devices following in a diesel exhaust aftertreatment line: particulate filter (soot oxidation) and SCR or LNT catalyst (NOx reduction).In this paper, we present a global kinetic model of a diesel oxidation catalyst, including PtOx formation induced by reactions with O2 and NO2, PtOx reduction by CO, hydrocarbons and NO, and PtOx thermal decomposition, and use it to reveal the extent of NO2 yield variation in four standard driving cycles for passenger car emission tests: NEDC, FTP, US06 and SC03. During a single driving cycle, the NO2 yield decreases by 3–10% relative to the original level of the reduced catalyst. The PtOx formation is a slow process and stabilizes only after approximately four repeated driving cycles. The stabilized NO2 yield is 7–27% (relative) lower than with the reduced catalyst, depending mainly on the history of operating temperatures. The largest variation is observed around 250–300°C. At lower temperatures, PtOx are partly reduced during CO and hydrocarbon peaks in the engine exhaust during dynamic operation. At higher temperatures, PtOx start to decompose and NO oxidation becomes limited by equilibrium.

Mechanistic assessments of NO oxidation turnover rates and active site densities on WO3-promoted CeO2 catalysts

The effects of NO, NO2 and O2 pressures on NO oxidation rates and UV-visible spectra are used here to assess the elementary steps and the number and type of redox-active sites involved in NO oxidation on CeO2 promoted by contact with WO3 domains. The reversible chemisorption of O2 on vacancies (∗) and the subsequent dissociation of O2∗ assisted by NO to form O∗ and NO2 are the kinetically-relevant steps on surfaces with O∗ coverage set by NO−NO2 equilibration. O2p→Ce4f ligand-to-metal charge transfer (LMCT) bands probe the rate constants for O2∗ formation and desorption at catalytic conditions; their comparison with those derived from rate data confirms the mechanistic conclusions and the involvement of CeO2 surfaces promoted by contact with WO3 domains. These data allow an accurate assessment of the number and type of redox-active sites, thus allowing reactivity comparisons among catalysts based on turnover rates. The number of redox-active sites increased with increasing W surface density (2.1–9.5W/nm2), but NO oxidation turnover rates were essentially unchanged. These elementary steps and active structures differ markedly from those that mediate NO oxidation on Pt, PdO, RhO2 and Co3O4 catalysts. Turnover rates are similar on WO3/CeO2 and Pt-based catalysts at practical temperatures of diesel exhaust treatment (∼500K), but WO3/CeO2 catalysts exhibit much higher rates based on catalyst mass (>10-fold), thus rendering useful as less costly and more resilient alternatives to noble metals. These findings illustrate a method to probe the number and type of redox-active sites and conceptual insights into the pathways that mediate the chemisorption and activation of O2 by isolated vacancies and the subsequent dissociation of OO bonds by assistance from co-reactants.

Hydrothermal Aging Effects on Fe/SSZ-13 and Fe/Beta NH3–SCR Catalysts

Fe/SSZ-13 and Fe/beta catalysts with similar Fe loading and Si/Al ratios were prepared via solution ion-exchange under N2. These catalysts, in both freshly prepared and hydrothermally aged forms, were characterized with temperature-programmed reduction/desorption and a few spectroscopic methods to elucidate changes to Fe species and zeolite acidity during hydrothermal aging. The catalytic properties were further studied using standard/fast SCR and NO/NH3 oxidation reactions. For both catalysts, aging causes Fe-ion clustering and Al–Fe interactions. A clear correlation is found between standard NH3–SCR and NO oxidation activities indicating that higher NO oxidation rates enable fast SCR even under standard SCR conditions. For fast SCR, higher pore opening and lower acidity in beta zeolite-based catalysts mitigate NH4NO3 deposition.

Simultaneous Oxidation and Absorption of NOx and SO2 in an Integrated O3 Oxidation/Wet Atomizing System

The simultaneous removal of NOx and SO2 was demonstrated by an integrated O3 oxidation/wet atomizing system. The dielectric barrier discharge with silicone rubber dielectrics was used for generating O3 to oxidize NO and SO2. The O3 yield and O3 energy yield were evaluated to be 13.3 g/h and 53.7 g/kWh, respectively. NO was effectively oxidized by O3, while SO2 was not significantly oxidized because the reaction rate of NO oxidation was much higher than that of SO2. The highest oxidation efficiencies of NO and SO2 were 97 and 8%, respectively. NOx and SO2 were absorbed as aqueous ions with a mist of H2O2 solution supplied by an ultrasonic humidifier. The total removal efficiencies of NOx and SO2 were 88.8 and 100%, respectively. NO and SO2 were oxidized to NO2, HNO3, N2O5, and SO3 by O3. These species were absorbed to form NO3–, HSO3–, and SO42– by reactions with the H2O2 solution.

Macrokinetics of NO Oxidation by Vaporized H2O2 Association with Ultraviolet Light

The macrokinetics of NO oxidation by vaporized H2O2 association with ultraviolet light was evaluated. The effects of various influencing factors on the NO oxidation rate were investigated, such as the H2O2 concentration, the H2O2 pH, the reaction temperature, the UV energy density, the UV light wavelength, the coexistence of gases (SO2 and O2), and the radical scavenger tert-butanol. The NO oxidation was conformed to a pseudo-first-order kinetics pattern under the experimental conditions. The rate constants determined at 373–413 K fitted the Arrhenius equation well, yielding an apparent activation energy of 20.8 kJ/mol. The experimental results indicated that both UV power density and UV light wavelength exhibited significant influences on NO oxidation, and decreasing pH and increasing O2 concentration could enhance NO oxidation. A mechanism of NO oxidation was also proposed.

Photocatalytic concrete pavements: Laboratory investigation of NO oxidation rate under varied environmental conditions

Concrete pavements containing TiO2 can be used for air pollution control by oxidizing NOX under UV-bearing sunlight. This study employed a bench-scale photoreactor to estimate NO oxidation rates for varied environmental conditions. Rates correlated positively with NO inlet concentration and irradiance and negatively with relative humidity. No correlation occurred with flow rate. A decrease in slab moisture (previously unstudied) positively correlated with NO oxidation rate at 0–2% loss of saturated mass, but negatively correlated at losses greater that 2%. Although prior researchers deemed temperature insignificant, data indicated a positive correlation. Overall, rates ranged from 9.8 to 64nmol·m−2·s−1.

DFT Analysis of NO Oxidation Intermediates on Undoped and Doped LaCoO3 Perovskite

Perovskites are of interest as low-cost replacements for Pt-based NO oxidation catalysts. While the mechanism of Pt-catalyzed NO oxidation is fairly well understood, such is not the case for the oxides. The perovskite LaCoO3 itself has been shown to have good NO oxidation activity, and Sr substitution improves NO oxidation rates and reduces NO2 inhibition. In this work, we report density functional theory (DFT) results for the adsorption of NOx (x = 1, 2) to the undoped and Sr doped (100) LaO and CoO2 terminated LaCoO3. Further, we used first-principles thermodynamic models to determine the most common surface species under NO oxidation conditions. Nitrates and adsorbed NO are most stable on the LaO and CoO2 terminations, respectively. We explored the relative free energies of surface and vacancy-mediated pathways for NO oxidation. The vacancy-mediated pathways suffer from energetically costly removal of surface oxygen, while the surface pathway is most feasible for NO oxidation to occur. The perovskite s...

Oxyfuel derived CO2 compression experiments with NOx, SOx and mercury removal—Experiments involving compression of slip-streams from the Callide Oxyfuel Project (COP)

Oxyfuel combustion is a CO2 capture technology which is approaching commercial demonstration. Of practical interest is the use of the compression circuit to allow low-cost cleaning options for various flue gas impurities. This work has focussed on three species – NOx SOx and Hg – and their removal during compression of “real” oxyfuel flue gas sampled as a slip stream from the demonstration Callide Oxyfuel Project. The flue gas slip stream was compressed using a bench-scale piston compressor developed to allow measurements of impurity concentrations after each compression stage using adjustable pressures. Several operating configurations were investigated including variable pressures from 5 to 30bar, interstage temperature changes and flow rate. Slip streams taken before and after SOx removal allowed the impact of mixed NOx/SOx gases to also be investigated. The results from the “real” oxyfuel flue gas experiments for the three species were similar to those performed in the laboratory using synthetic flue gas and reported previously. The capture of SO2 was found at be greater at low pressures than NOx capture, with 90% removal of SO2 by a pressure of 10bar, with NOx capture extending to higher pressures. The effect of residence time during compression had the greatest influence at higher pressures (>10bar) where the kinetic rate of NO oxidation to NO2 increases less with pressure increase. Capture of NOx was increased from 55% to 75% by doubling the residence time in the compressor and could be further extended to 83% by increasing back end pressure from 24bar to 30bar. Lowering the temperature during compression produced the greatest NOx and Hg capture. Overall, the results indicate that capture of mercury during compression occurred as a consequence of high pressure, longer residence time and concentration of NO2.

Oxidation of zeolite acid sites in NO/O2 mixtures and the catalytic properties of the new site in NO oxidation

The NO oxidation reaction kinetics over a number of zeolite structures were investigated at temperatures above 423K using plug-flow microreactors and in situ FTIR spectroscopy. Fast catalytic NO oxidation rates (up to 1000×) are observed over H- and Na-exchanged zeolite frameworks (BEA, MFI, and CHA) at temperatures above 423K with respect to the gas-phase reaction. NO oxidation rates increase with temperature over H- and Na-zeolites, while siliceous zeolites display little activity. Activation energies scale in the order of CHA<MFI<BEA (40.8–55.5kJmol−1), and application of transition state theory shows that the formation of the activated complex is an enthalpically controlled process that benefits from smaller zeolite pore size. In all samples, rates are proportional to NO and O2 concentrations, in contrast to low-temperature catalytic rates Loiland et al. [33], which are second order in NO and first order in O2. This difference indicates that a new reaction mechanism is operative above 423K. In-situ FTIR studies reveal that NO+ coordinated at framework sites in the zeolite pores (SiO−(NO+)Al) plays a direct role in the catalysis, and they also reveal that the NO oxidation rate is proportional to the amount of NO+ present in the sample. Furthermore, it is found that NO+ is in equilibrium with gas-phase NO and that desorption of NO+ (as NO) yields an oxidized acid site (SiOAl). No evidence of NO+ formation is observed over the siliceous zeolite samples. A working model of the reaction mechanism for the high-temperature NO oxidation reaction is proposed for acidic zeolites that is consistent with the observed form of the rate equation and the observed NO+ reaction intermediate.

Characterization and activity of N doped TiO2 supported VPO catalysts for NO oxidation

Nitrogen (N) doped TiO2 supported vanadium phosphorus oxide (VPO) catalysts were prepared and tested for catalytic oxidation of NO. The experimental results showed that 0.1V(5)PO/TiN(1) was the optimal catalyst for NO oxidation and the NO conversion could reach 61% at temperature of 350°C. The physico–chemical properties of 0.1V(5)PO/TiN(1) catalyst were characterized by Brunauer–Emmett–Teller measurements (BET), Photoluminescence (PL), X–ray photoelectron spectroscopy (XPS), Infrared spectroscopy measurements of NH3 adsorbed on catalysts (NH3–IR), and Infrared Fourier transform spectroscopy (FTIR). The PL and XPS spectra revealed that the oxygen storage capacity and catalytic activity of VPO/Ti catalyst can be improved by nitrogen doping. The H2–TPR profile also indicated that V(5)PO/TiN(1) catalyst had a superior redox property. Activity test results and FTIR spectra showed that 0.1V(5)PO/TiN(1) catalysts had a superior resistivity to SO2 and the NO oxidation rate is above 50% at temperature of 350°C when SO2 concentration is 200ppm to 800ppm.