Experimental and detailed kinetic modeling study of the high pressure oxidation of methanol sensitized by nitric oxide and nitrogen dioxide

The perturbation of the combustion by NO_x is important in several practical systems (recent NO_x-reduction strategies, combustion with exhaust-gas recirculation in diesel and HCCI engines and for mild combustion). New experimental results were obtained for the oxidation of methanol in absence and in presence of NO or NO₂ in a fused silica jet-stirred reactor operating at 10 atm, over the temperature range 700-1100 K. Probe sampling followed by on-line FTIR analyses and off-line GC-TCD/FID analyses permitted to measure the concentration profiles of the reactants, stable intermediates and the final products. A detailed chemical kinetic modeling of the present experiments was performed. An overall good agreement between the present data and this modeling was obtained. The oxidation of methanol is significantly sensitized by NO₂, whereas the effect of NO is more limited. According to the proposed model, the mutual sensitization of the oxidation of methanol and NO proceeds through the NO to NO₂ conversion by HO₂. The increased production of OH resulting from the oxidation of NO by HO₂ promotes the oxidation of the fuel. A simplified reaction scheme can be proposed for the NO-seeded oxidation of methanol: NO + HO₂ ⇒ NO₂ + OH followed by OH + CH₃OH ⇒ H₂O + CH₂OH and CH₃O. The enhanced oxidation of methanol by addition of NO₂ is also due to additional OH production through: NO₂ + HO₂ ⇒ HONO + O₂, NO₂ + H ⇒ NO + OH and HONO ⇒ NO + OH followed by OH + CH₃OH ⇒ CH₂OH and CH₃O. The further reactions CH₂OH + O₂ ⇒ CH₂O + HO₂; CH₃O ⇒ CH₂O + H; CH₂O + OH ⇒ HCO; HCO + O₂ ⇒ HO₂ and H + O₂ ⇒ HO₂ complete the sequence whether NO or NO₂ is added.     

Experimental and kinetic modeling study of C2H4 oxidation at high pressure

A detailed chemical kinetic model for oxidation of C₂H₄ in the intermediate temperature range and high pressure has been developed and validated experimentally. New ab initio calculations and RRKM analysis of the important C₂H₃ + O₂ reaction was used to obtain rate coefficients over a wide range of conditions (0.003-100 bar, 200-3000 K). The results indicate that at 60 bar and medium temperatures vinyl peroxide, rather than CH₂O and HCO, is the dominant product. The experiments, involving C₂H₄/O₂ mixtures diluted in N₂, were carried out in a high pressure flow reactor at 600-900 K and 60 bar, varying the reaction stoichiometry from very lean to fuel-rich conditions. Model predictions are generally satisfactory. The governing reaction mechanisms are outlined based on calculations with the kinetic model. Under the investigated conditions the oxidation pathways for C₂H₄ are more complex than those prevailing at higher temperatures and lower pressures. The major differences are the importance of the hydroxyethyl (CH₂CH₂OH) and 2-hydroperoxyethyl (CH₂CH₂OOH) radicals, formed from addition of OH and HO₂ to C₂H₄, and vinyl peroxide, formed from C₂H₃ + O₂. Hydroxyethyl is oxidized through the peroxide HOCH₂CH₂OO (lean conditions) or through ethenol (low O₂ concentration), while 2-hydroperoxyethyl is converted through oxirane.     

Theoretical rate coefficients for the reaction of methyl radical with hydroperoxyl radical and for methylhydroperoxide decomposition

The kinetics of the CH₃ + HO₂ bimolecular reaction and the thermal decomposition of CH₃OOH are studied theoretically. Direct variable reaction coordinate transition state theory (VRC-TST), coupled with high level multireference electronic structure calculations, is used to compute capture rates for the CH₃ + HO₂ reaction and to characterize the transition state of the barrierless CH₃O + OH product channel. The CH₂O + H₂O product channel and the CH₃ + HO₂ → CH₄ + O₂ reaction are treated using variational transition state theory and the harmonic oscillator and rigid rotor approximations. Pressure dependence and product branching in the bimolecular and decomposition reactions are modeled using master equation simulations. The predicted rate coefficients for the major products channels of the bimolecular reaction, CH₃O + OH and CH₄ + O₂, are found to be in excellent agreement with values obtained in two recent modeling studies. The present calculations are also used to obtain rate coefficients for the CH₃O + OH association/decomposition reaction.     

NO-methanol interaction on the surface of Pt(3 3 2)

The interaction between NO and CH₃OH on the surface of stepped Pt(3 3 2) was investigated using Fourier transform infra red reflection-absorption spectroscopy (FTIR-RAS) and thermal desorption spectroscopy (TDS). At 90 K, pre-dosed CH₃OH molecules preferentially adsorb on step sites, suppressing the adsorption of NO molecules on the same sites. However, due to a much stronger interaction with Pt, at 150 K and higher, the adsorption of NO molecules on step sites is restored, giving rise to peaks closely resembling those of NO molecules adsorbed on clean Pt(3 3 2) surface. Adsorbed CH₃OH is very reactive on this surface, and is readily oxidized to formate in the presence of O₂, even at 150 K. In contrast, reactions between CH₃OH and co-adsorbed NO are slight to non-existent. There are no new peaks in association with intermediates resulting from CH₃OH-NO interactions. It is concluded that the reduction of NO with CH₃OH on Pt(3 3 2) does not proceed through a mechanism of forming intermediates.     

Air-broadening coefficients of the HO2 radical in the 2ν1 band measured using cw-CRDS

In this paper we present measurements of the air-broadening coefficients of HO₂ at room temperature in the 2ν₁ band around 1.5 microns. The HO₂ radicals were created by flash photolysis of SOCl₂ in a flow of O₂/CH₃OH mixtures. To observe air-broadening, N₂ (79%) and O₂ (21%) were added using calibrated flow controllers and a total pressure controller. The total pressure was monitored in parallel using a capacitive pressure gauge. Air-broadening coefficients at 296 K were determined for 34 absorption lines between 6631 and 6671 cm⁻¹. The air-broadening coefficients of HO₂ show a rotational dependence (decreasing from about 0.14 cm⁻¹/atm for N″ = 3 to about 0.09 cm⁻¹/atm for N″ = 10). No evidence for collisional narrowing was observed.     

A DFT study on the formation of CH3O on Cu2O(1 1 1) surface by CH3OH decomposition in the absence or presence of oxygen

The formation mechanism of CH₃O by the adsorption and decomposition of CH₃OH on clean and oxygen-precovered Cu₂O(1 1 1) surface has been investigated with density functional theory method together with the periodic slab models. Two possible formation pathways of CH₃O by CH₃OH decomposition on oxygen-precovered (O_pre) Cu₂O(1 1 1) surface were proposed and discussed. One is the O-H bond-cleavage of CH₃OH with H migration to O_pre to form CH₃O; the other is the C-O bond-scission of CH₃OH with CH₃ migration to O_pre leading to CH₃O_pre. The calculated results show that the O-H bond-breaking path has the lowest activation barrier 26.8 kJ mol⁻¹, the presence of oxygen-precovered on Cu₂O(1 1 1) surface exhibits a high surface reactivity toward the formation of CH₃O by the O-H bond-cleavage of CH₃OH, and reduce the activation barrier of O-H bond-cleavage. The C-O bond-breaking path was inhibited by dynamics, suggesting that the O atom of CH₃O is not from the oxygen-precovered, but comes from the O of CH₃OH. Meanwhile, the calculated results give a clear illustration about the formation mechanism of CH₃O in the presence of oxygen and the role of oxygen at the microscopic level.     

Shock tube measurements of ignition delay times and OH time-histories in dimethyl ether oxidation

Ignition delay times and OH concentration time-histories were measured in DME/O₂/Ar mixtures behind reflected shock waves. Initial reflected shock conditions covered temperatures (T₅) from 1175 to 1900 K, pressures (P₅) from 1.6 to 6.6 bar, and equivalence ratios (?) from 0.5 to 3.0. Ignition delay times were measured by collecting OH^∗ emission near 307 nm, while OH time-histories were measured using laser absorption of the R₁(5) line of the A-X(0,0) transition at 306.7 nm. The ignition delay times extended the available experimental database of DME to a greater range of equivalence ratios and pressures. Measured ignition delay times were compared to simulations based on DME oxidation mechanisms by Fischer et al. [7] and Zhao et al. [9]. Both mechanisms predict the magnitude of ignition delay times well. OH time-histories were also compared to simulations based on both mechanisms. Despite predicting ignition delay times well, neither mechanism agrees with the measured OH time-histories. OH Sensitivity analysis was applied and the reactions DME ↔ CH₃O + CH₃ and H + O₂ ↔ OH + O were found to be most important. Previous measurements of DME ↔ CH₃O + CH₃ are not available above 1220 K, so the rate was directly measured in this work using the OH diagnostic. The rate expression k[1/s] =  1.61 × 10⁷⁹T^−18.4 exp(−58600/T), valid at pressures near 1.5 bar, was inferred based on previous pyrolysis measurements and the current study. This rate accurately describes a broad range of experimental work at temperatures from 680 to 1750 K, but is most accurate near the temperature range of the study, 1350-1750 K. When this rate is used in both the Fischer et al. and Zhao et al. mechanisms, agreement between measured OH and the model predictions is significantly improved at all temperatures.     

Thermal reactions of 2-iodoethanol on Cu(1 0 0)

Temperature-programmed reaction/desorption, X-ray photoelectron spectroscopy, and reflection-absorption infrared spectroscopy have been employed to investigate the reactions of ICH₂CH₂OH on Cu(1 0 0) under ultrahigh-vacuum conditions. ICH₂CH₂OH can dissociate on Cu(1 0 0) at 100 K, forming a -CH₂CH₂OH surface intermediate. Density functional theory calculations predict that the -CH₂CH₂OH is most probably adsorbed on atop site. -CH₂CH₂OH on Cu(1 0 0) further decomposes to yield C₂H₄ below 270 K. No evidence shows the formation of -CH₂CH₂O- intermediate in the reactions of ICH₂CH₂OH on Cu(1 0 0) in contrast to the decomposition of BrCH₂CH₂OH on Cu(1 0 0) and ICH₂CH₂OH on Ag(1 1 1) and Ag(1 1 0), exhibiting the effects of carbon-halogen bonds and metal surfaces.     

Theoretical study on the kinetics for OH reactions with CH3OH and C2H5OH

Kinetics and mechanisms for reactions of OH with methanol and ethanol have been investigated at the CCSD(T)/6-311 + G(3df, 2p)//MP2/6-311 + G(3df, 2p) level of theory. The total and individual rate constants, and product branching ratios for the reactions have been computed in the temperature range 200-3000 K with variational transition state theory by including the effects of multiple reflections above the wells of their pre-reaction complexes, quantum-mechanical tunneling and hindered internal rotations. The predicted results can be represented by the expressions k₁ = 4.65 × 10⁻²⁰ × T^2.68 exp(414/T) and k₂ = 9.11 × 10⁻²⁰ × T^2.58 exp(748/T) cm³ molecule⁻¹ s⁻¹ for the CH₃OH and C₂H₅OH reactions, respectively. These results are in reasonable agreements with available experimental data except that of OH + C₂H₅OH in the high temperature range. The former reaction produces 96-89% of the H₂O + CH₂OH products, whereas the latter process produces 98-70% of H₂O + CH₃CHOH and 2-21% of the H₂O + CH₂CH₂OH products in the temperature range computed (200-3000 K).     

Measurements of H2O2 in low temperature dimethyl ether oxidation

H₂O₂ is one of the most important species in dimethyl ether (DME) oxidation, acting not only as a marker for low temperature kinetic activity but also responsible for the “hot ignition” transition. This study reports, for the first time, direct measurements of H₂O₂ and CH₃OCHO, among other intermediate species concentrations in helium-diluted DME oxidation in an atmospheric pressure flow reactor from 490 to 750 K, using molecular beam electron-ionization mass spectrometry (MBMS). H₂O₂ measurements were directly calibrated, while a number of other species were quantified by both MBMS and micro gas chromatography to achieve cross-validation of the measurements. Experimental results were compared to two different DME kinetic models with an updated rate coefficient for the H + DME reaction, under both zero-dimensional and two-dimensional physical model assumptions. The results confirm that low and intermediate temperature DME oxidation produces significant amounts of H₂O₂. Peroxide, as well as O₂, DME, CO_, and CH₃OCHO profiles are reasonably well predicted, though profile predictions for H₂/CO₂ and CH₂O are poor above and below ～625 K, respectively. The effect of the collisional efficiencies for the H + O₂ + M = HO₂ + M reaction on DME oxidation was investigated by replacing 20% He with 20% CO₂. Observed changes in measured H₂O₂ concentrations agree well with model predictions. The new experimental characterizations of important intermediate species including H₂O₂, CH₂O and CH₃OCHO, and a path flux analysis of the oxidation pathways of DME support that kinetic parameters for decomposition reactions of HOCH₂OCO and HCOOH directly to CO₂ may be responsible for model under-prediction of CO₂. The H abstraction reactions for DME and/or CH₂O and the unimolecular decomposition of HOCH₂O merit further scrutiny towards improving the prediction of H₂ formation.     

High-temperature measurements of the rates of the reactions CH2O + Ar → Products and CH2O + O2 → Products

The two-channel thermal decomposition of formaldehyde [CH₂O], (1a) CH₂O + Ar → HCO + H + Ar, and (1b) CH₂O + Ar → H₂ + CO + Ar, was studied in shock tube experiments in the 2258-2687 K temperature range, at an average total pressure of 1.6 atm. OH radicals, generated on shock heating trioxane-O₂-Ar mixtures, were monitored behind the reflected shock front using narrow-linewidth laser absorption. 1,3,5 trioxane [C₃H₆O₃] was used as the CH₂O precursor in the current experiments. H-atoms formed upon CH₂O and HCO decomposition rapidly react with O₂ to produce OH via H + O₂ → O + OH. The recorded OH time-histories show dominant sensitivity to the formaldehyde decomposition pathways. The second-order reaction rate coefficients were inferred by matching measured and modeled OH profiles behind the reflected shock. Two-parameter fits for k_1a and k_1b, applicable in this temperature range, are:

     

Configuration dependence of photon stimulated ion desorption from methyl ester compounds induced by core excitation

Photon stimulated ion desorption (PSID) from methyl ester terminated self-assembled monolayer (MHDA-SAM, HS(CH₂)₁₅COOCH₃) and methyl mercaptoacetate (MA, HSCH₂COOCH₃) on Ag has been investigated using soft X-ray in the C and O K-edge regions. In MHDA-SAM on Ag, site-selective ion desorption has been clearly observed at resonant core excitations of C_1s, O_1s(OCH₃) → σ^∗(OCH₃) and O_1s(OCH₃) → σ^∗(COCH₃). Ion intensity in MA on Ag is obviously reduced for (n = 1-3) at C_1s, O_1s(OCH₃) → σ^∗(OCH₃) excitations, and no site-selective reaction at O_1s(OCH₃) → σ^∗(COCH₃) excitations has been observed. These reactions may be influenced by configurational difference of reactive sites. It is suggested that surface effects on the selective reaction due to positioning methyl ester group near the surface plays an important role.     

Kinetic study of chlorine behavior in the waste incineration process

The waste incineration atmosphere was simulated as HCl/H₂O/O₂/CO₂/N₂ in order to experimentally study chlorine behavior as temperature ranges from 1173 to 1473 K and residence time varies. The results show that Cl radicals, produced by the decomposition of HCl at high temperature, mainly recombine to form Cl₂ and HCl at the quenching section. It was found that temperature, residence time, cooling rate and feeding gas composition influence Cl₂ concentration. To thoroughly understand this reaction system, a kinetic model was developed and validated against experimental results. The key reactions and main pathway were found out with the use of sensitivity and rate of production analysis (ROP). The reaction HCl + O₂ → Cl + HO₂ was shown to initiate the reaction system, and it was found that a significant amount of Cl₂ was simultaneously produced by the following high temperature reaction: Cl + HOCl → Cl₂ + OH. In the cooling process, the main consumption reactions of Cl radicals were H₂O + Cl → HCl + OH, OH + Cl → HCl + O and Cl + Cl + M → Cl₂ + M. Among these, the first two reactions can be used to explain the effect of H₂O on the concentration of Cl radical at high temperature. In addition, the influence of the quenching rate on the distribution of chlorine was found to occur because of the varying effects that temperature change causes to the different Cl radical consumption reactions.     

Measurements of nitrogen-broadening coefficients in the ν3 band of the hydroperoxyl radical using a continuous wave quantum cascade laser

Mid-infrared absorption spectroscopy was applied to the detection of the hydroperoxyl radical (HO₂) in pulsed laser photolysis combined with a laser absorption kinetics reactor. The transition of the ν₃ vibrational band assigned to the O-O stretch mode around 1065 cm⁻¹ was probed with a thermoelectrically cooled, continuous wave, mid-infrared, distributed feedback quantum cascade laser (QCL). The HO₂ was generated through 355 nm photolysis of Cl₂/1,4-c-C₆H₈/O₂ mixtures. The mid-infrared absorption spectrum of the HO₂ radical was recorded between 1064 and 1065.5 cm⁻¹. The absorption line shapes were well represented by the Voigt profile. The nitrogen-broadening coefficients of the HO₂ radical at 295 K were determined for four absorption lines around 1065 cm⁻¹. Mid-infrared absorption detection using a QCL as a spectroscopic light source is a powerful method in spectroscopic and kinetics studies of the HO₂ radical.     

Facile fabrication of Zn/Zn5(OH)8Cl2·H2O flower-like nanostructure on the surface of Zn coated with poly (N-methyl pyrrole)

Zn/Zn₅(OH)₈Cl₂·H₂O flower-like nanostructures was electrodeposited on the coated Zn with poly (N-methyl pyrrole) in 0.1 M Zn (NO₃)₂ and 0.1 M KCl solution. The morphology and the structure of the Zn/Zn₅(OH)₈Cl₂·H₂O were characterized by Field Emission Scanning Electron Microscopy (FESEM), Fourier transform infrared (FT-IR) spectroscopy and X-ray diffraction analysis (XRD). The FT-IR results showed special peaks at 908 and 728 cm⁻¹ related to Zn₅(OH)₈Cl₂·H₂O. The FESEM results indicated that Zn/Zn₅(OH)₈Cl₂·H₂O consists of a flower-like nanostructure and these flower-shaped structures contain many shaped nanopetals with the thickness of 27.8 nm. The XRD result confirmed that the major phase of electrodeposited product in 0.1 M KCl as supporting electrolyte was Zn₅(OH)₈Cl₂·H₂O. The ability of PMPy to create a thin film and the existence of several pores in its matrix act as a mold for the growth of Zn/Zn₅(OH)₈Cl₂·H₂O flower-like nanostructure. The trapping of Cl⁻ and OH⁻ within pores can be considered as the reason for the formation of flowerlike Zn/Zn₅(OH)₈Cl₂·H₂O nanostructures in 0.1 M KCl.     

Methanol oxidation up to 100 atm in a supercritical pressure jet-stirred reactor

Methanol (CH₃OH) has attracted considerable attention as a renewable fuel or fuel additive with low greenhouse gas emissions. Methanol oxidation was studied using a recently developed supercritical pressure jet-stirred reactor (SP-JSR) at pressures of 10 and 100 atm, at temperatures from 550 to 950 K, and at equivalence ratios of 0.1, 1.0, and 9.0 in experiments and simulations. The experimental results show that the onset temperature of CH₃OH oxidation at 100 atm is around 700 K, which is more than 100 K lower than the onset at 10 atm and this trend cannot be predicted by the existing kinetics models. Furthermore, a negative temperature coefficient (NTC) behavior was clearly observed at 100 atm at fuel rich conditions for methanol for the first time. To understand the observed temperature shift in the reactivity and the NTC effect, we updated some key elementary reaction rates of relevance to high pressure CH₃OH oxidation from the literature and added some new low-temperature reaction pathways such as CH₂O + HO₂ = HOCH₂O₂ (RO₂), RO₂ + RO₂ = HOCH₂O (RO) + HOCH₂O (RO) + O₂, and CH₃OH + RO₂ = CH₂OH + HOCH₂O₂H (ROOH). Although the model with these updates improves the prediction somewhat for the experimental data at 100 atm and reproduces well high-temperature ignition delay times and laminar flame speed data in the literature, discrepancies still exist for some aspects of the 100 atm low-temperature oxidation data. In addition, it was found that the pressure-dependent HO₂ chemistry shifts to lower temperature as the pressure increases such that the NTC effect at fuel-lean conditions is suppressed. Therefore, as shown in the experiments, the NTC phenomenon was only observed at the fuel-rich condition where fuel radicals are abundant and the HO₂ chemistry at high pressure is weakened by the lack of oxygen resulting in comparatively little HO₂ formation.     

The reaction of hydroxyethyl radicals with O2: A theoretical analysis and experimental product study

Reactions of α-hydroxyethyl (CH₃CHOH) and β-hydroxyethyl (CH₂CH₂OH) radicals with oxygen are of key importance in ethanol combustion. High-level ab initio calculations of the potential energy surfaces of these two reactions were coupled with master equation methods to compute rate coefficients and product branching ratios for temperatures of 250-1000 K. The α-hydroxyethyl + O₂ reaction is controlled by the barrierless entrance channel and shows negligible pressure dependence; in contrast, the reaction of the β isomer displays pronounced pressure dependence. The high pressure limit rate coefficients of both reactions are about the same at the temperatures investigated. Products of the reactions were monitored experimentally at 4 Torr and 300-600 K using tunable synchrotron photoionization mass spectrometry. Hydroxyethyl radicals were produced from the reaction of ethanol with chlorine atoms and the β isomer was also selectively produced by the addition reaction C₂H₄ + OH → CH₂CH₂OH. Formaldehyde, acetaldehyde, vinyl alcohol and H₂O₂ products were detected, in qualitative agreement with the theoretical predictions.     

Synthesis and Sm/Sm doping effects on photoluminescence properties of Sr4Al14O25

Complete and partial samarium reduction was achieved under strong reducing atmosphere by solid-state and combustion synthesis of Sr_3.96Sm_0.04Al₁₄O₂₅. Dependence of different fluxing agents on the formation of various strontium aluminates was examined. The samples were investigated by X-ray powder diffraction, temperature dependent luminescence decay and photoluminescence measurements. Excitation with UV radiation resulted in sharp and well resolved emission lines of samarium ions. Distinct temperature behavior for Sm²⁺ and Sm³⁺ were detected in the range of 100-500 K. Estimated emission thermal quenching values (TQ_1/2) for divalent samarium were approximately 270 K while for trivalent state around 660 K. Measured luminescence decay values of Sm²⁺ are substantially lower than for Sm³⁺,≈1.7 and ≈2.7 ms, respectively. The spectral feature of Sm²⁺ emission spectrum indicates that dopant occupies low symmetry site in Sr₄Al₁₄O₂₅ compound.     

Exploring the low-temperature oxidation chemistry of 1-butene and i-butene triggered by dimethyl ether

In order to better understand the low-temperature oxidation chemistry of alkenes, 1-butene and i-butene oxidation experiments triggered by dimethyl ether (DME) were conducted in a jet-stirred reactor at 790 Torr, 500–725 K and the equivalence ratio of 0.35. Low-temperature oxidation intermediates involved in alcoholic radical chemistry and allylic radical chemistry were detected by using synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS). To better interpret the experimental data, a kinetic model was proposed based on our low-temperature oxidation model of DME and comprehensive oxidation models of 1-butene and i-butene in literature. Based on present experimental results and modeling analysis, alcoholic radical chemistry initiated by OH addition is mainly responsible for the low-temperature chain propagation of butenes, since the Waddington mechanism plays a dominant role compared with the chain-branching pathways through the second O₂ addition. Allylic radical+HO₂ reactions producing alkenyl hydroperoxides and fuel+O₂ serve as the major chain-branching and chain-termination pathways, respectively, and they are competitive in the negative temperature coefficient (NTC) region. In contrast, chain-branching pathways originating from allylic radical+O₂ and alkyl-like radical+O₂ reactions have little contribution to the OH formation. Comparison with the simulation results of butane/DME mixtures demonstrates that butenes can largely inhibit the reactivity of DME at low temperatures due to its reduced low-temperature chain-branching process. However, in the NTC region, butenes may not be good OH absorbents since the allylic radicals can convert HO₂ to OH and consequently enhance the oxidation reactivity.     

The role of co-adsorbed O2 on the catalytic reduction of NO with C2H5OH on the surface of Pt(3 3 2)

The influence of pre-dosed O₂ on the catalytic reduction of NO with ¹³C₂H₅OH on the surface of stepped Pt(3 3 2) was investigated using Fourier transform infra red reflection-absorption spectroscopy (FTIR-RAS) and thermal desorption spectroscopy (TDS). We show that the oxidation of ¹³C₂H₅OH with O₂ is a very effective reaction, occurring at 150 K and giving rise to acetate. The presence of NO does not lead to any evident oxidation of ¹³C₂H₅OH irrespective of the annealing temperature. For the case of O₂ + ¹³C₂H₅OH + NO co-adlayers, oxidation of ¹³C₂H₅OH also takes place at 150 K. However, no new surface species that are supposed to be an intermediate for the production of N₂ are detected.The influence of O₂ on the production and desorption of N₂ is intimately related to both O₂ and ¹³C₂H₅OH coverage. The presence of pre-dosed O₂ does not greatly promote N₂ desorption. In fact, N₂ desorption is suppressed quantitatively with increasing O₂ coverage, after which unreacted, or left-over O atoms appear and remain on steps. It is concluded that the presence of pre-dosed O₂ does not play a role of activating reactants in the catalytic reduction of NO with ¹³C₂H₅OH on the surface of Pt(3 3 2).