Kinetic Analysis of O<sub>2</sub>- and NO<sub>2</sub>-Based Oxidation of Synthetic Soot

Wang-Hansen, Carolin; Soltani, Soheil; Andersson, Bengt

doi:10.1021/jp307789r

Cited by 15 publications

(10 citation statements)

References 42 publications

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“…Calculated adsorption energies and structural parameters for the binding of NO to the defected Mn-doped CeO 2 (111) surface. , which has superior oxidation activity (Wang-Hansen et al, 2013). Consequently, the activity of the catalyst surface is enhanced because active oxygen is formed for oxidation reactions.…”

Section: Co-adsorption Of No and O 2 On Defective Mn-doped Ceo 2 (111mentioning

confidence: 99%

NO Adsorption and Oxidation on Mn Doped CeO2 (111) Surfaces: A DFT+U Study

Liu¹,

Zheng²,

Wang³

et al. 2018

Aerosol Air Qual. Res.

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The adsorption of NO molecules on Mn-doped CeO 2 (111) surfaces for NO oxidation has been studied by employing the periodic density functional theory plus U (DFT+U) method. Through our calculations, it is demonstrated how Mn-doped CeO 2 with superior NO oxidation activity benefits from the high mobility of the oxygen near the Mn cations. On unreduced Mn-doped CeO 2 (111) surfaces, the NO molecule preferentially interacted with the first neighboring O of the Mn cation, with the N also bonding to an Mn cation (E ads = -3.30 eV) or Ce cation (E ads = -2.90 eV). When NO adsorbs on the surface of defective Mn-doped CeO 2 with O 2 adsorbed in advance, an ONOO* four atoms species is formed on the surface (E ads = -2.51 eV and -2.02 eV), which is an intermediate and can decompose into NO 2 , NO 2 * and O*. The adsorption structure with higher adsorption energy has a closer geometry to NO 2 , indicating a deeper oxidation of NO. The calculation results indicate that the presence of Mn only has a strong effect on the nearby oxygen atoms and that the Mndoped CeO 2 surface has similar properties to a noble metal in NO oxidation catalysis. In DOS plots, the spin of the electron state of the adsorption structures involving the oxidation of NO is symmetric, indicating that electron transfer occurs from the slab to NO and strong covalent bonds are formed between N and O on the slab, which can also be confirmed by the charge density difference plots.

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Section: Co-adsorption Of No and O 2 On Defective Mn-doped Ceo 2 (111mentioning

confidence: 99%

NO Adsorption and Oxidation on Mn Doped CeO2 (111) Surfaces: A DFT+U Study

Liu¹,

Zheng²,

Wang³

et al. 2018

Aerosol Air Qual. Res.

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“…Oxidation of organic carbonaceous residues to CO and CO 2 by HNO 3 /NO x is well known in mass spectrometry research of NO 2 and HNO 3 27,28. Soot oxidation research and the automobile industry make use of carbon oxidation under high NO x conditions [29][30][31][32]. For instance, high NO x levels and enhanced temperatures in the vehicle exhaust are used to facilitate regeneration of diesel particulate filters and to burn off carbonaceous deposits to CO 2 .…”

mentioning

confidence: 99%

Inorganic Salt Interference on CO₂⁺ in Aerodyne AMS and ACSM Organic Aerosol Composition Studies

Pieber

Haddad

Slowik

et al. 2016

Environ. Sci. Technol.

105

121

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Aerodyne aerosol mass spectrometer (AMS) and Aerodyne aerosol chemical speciation monitor (ACSM) mass spectra are widely used to quantify organic aerosol (OA) elemental composition, oxidation state, and major environmental sources. The OA CO fragment is among the most important measurements for such analyses. Here, we show that a non-OA CO signal can arise from reactions on the particle vaporizer, ion chamber, or both, induced by thermal decomposition products of inorganic salts. In our tests (eight instruments, n = 29), ammonium nitrate (NHNO) causes a median CO interference signal of +3.4% relative to nitrate. This interference is highly variable between instruments and with measurement history (percentiles P = +0.4 to +10.2%). Other semi-refractory nitrate salts showed 2-10 times enhanced interference compared to that of NHNO, while the ammonium sulfate ((NH)SO) induced interference was 3-10 times lower. Propagation of the CO interference to other ions during standard AMS and ACSM data analysis affects the calculated OA mass, mass spectra, molecular oxygen-to-carbon ratio (O/C), and f. The resulting bias may be trivial for most ambient data sets but can be significant for aerosol with higher inorganic fractions (>50%), e.g., for low ambient temperatures, or laboratory experiments. The large variation between instruments makes it imperative to regularly quantify this effect on individual AMS and ACSM systems.

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“…Plots of the average, axial and radial temperature profiles for different configurations are shown in Figure . Axially, a temperature gradient of ∼32 °C is established over a single, 2‐cm long catalyst, which can result in roughly 70 % error in the estimated reaction rate constant for a typical oxidation reaction of soot with oxygen, based on the kinetic parameters extracted from the literature . Therefore, an inert monolith of the same length as the catalyst is inserted upstream the catalyst, which provides a higher radial heat transfer, resulting in a more uniform radial temperature profile at the inlet of the catalyst.…”

Section: Resultsmentioning

confidence: 99%

CFD characterization of monolithic reactors for kinetic studies

et al. 2014

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A laboratory reactor for kinetic studies has been simulated using computational fluid dynamics (CFD). Analysis of temperature distribution within the system shows that adding an inert monolith upstream the catalyst enhances heat conduction and therefore significantly reduces radial temperature gradients. Adjustment of the heating coil plays an important role as well by allowing the gas phase to smooth out the radial temperature profile. Radiative heat transfer and its effects on both the heat losses from the catalyst and on the measurements with an unprotected thermocouple have been particularly investigated. In order to prevent both the falsifying effect of radiation and the influences from the ongoing reaction, thermocouples should be placed and shielded inside a clogged channel. An inert monolith that is placed downstream the catalyst effectively serves as a radiation shield and drastically reduces both axial and radial gradients. Studies of the dispersion in the system reveal that the FTIR's gas cell is the most important source of the overall broadening in the concentration signal, with the reactor tube being the next major source of the distortion. An algorithm based on the Tikhonov regularization method has been developed for calculating the deconvolution of the concentration data, which has refined the time‐resolution in transient experiments from 20 to 2 s.

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Kinetic Analysis of O₂- and NO₂-Based Oxidation of Synthetic Soot

Cited by 15 publications

References 42 publications

NO Adsorption and Oxidation on Mn Doped CeO2 (111) Surfaces: A DFT+U Study

NO Adsorption and Oxidation on Mn Doped CeO2 (111) Surfaces: A DFT+U Study

Inorganic Salt Interference on CO₂⁺ in Aerodyne AMS and ACSM Organic Aerosol Composition Studies

CFD characterization of monolithic reactors for kinetic studies

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Kinetic Analysis of O2- and NO2-Based Oxidation of Synthetic Soot

Cited by 15 publications

References 42 publications

NO Adsorption and Oxidation on Mn Doped CeO2 (111) Surfaces: A DFT+U Study

NO Adsorption and Oxidation on Mn Doped CeO2 (111) Surfaces: A DFT+U Study

Inorganic Salt Interference on CO2+ in Aerodyne AMS and ACSM Organic Aerosol Composition Studies

CFD characterization of monolithic reactors for kinetic studies

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Kinetic Analysis of O₂- and NO₂-Based Oxidation of Synthetic Soot

Inorganic Salt Interference on CO₂⁺ in Aerodyne AMS and ACSM Organic Aerosol Composition Studies