Oxidation of Alkyl Ions, CnH2n+1+ (n = 1−5), in Reactions with O2 and O3 in the Gas Phase

Williams, Skip; Knighton, W. B.; Midey, Anthony J.; Viggiano, A. A.; Irle, Stephan; Morokuma, Keiji

doi:10.1021/jp031099+

Cited by 10 publications

(12 citation statements)

References 46 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Finally, the prevalence of ionic reactivity in the plasma produced by +DC corona can also explain the higher [CO]/[CO 2 ] ratio, with respect to a −DC corona 19. Thus, it was recently reported that alkyl cations react with ozone to form HCO + [Equation (20)] 42 …”

Section: Discussionmentioning

confidence: 99%

“…CO is then expected to be efficiently released by HCO + via fast exothermic proton transfer to any stronger base present in the plasma, notably water and ozone42 (proton affinity data are 594, 691 and 625.5 kJ · mol −1 for CO, H 2 O and O 3 , respectively) 34. Non ionic routes for the production of CO are known from studies of the tropospheric degradation of VOCs 14.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

DC Corona Electric Discharges for Air Pollution Control, 2—Ionic Intermediates and Mechanisms of Hydrocarbon Processing

Marotta

Callea

Ren

et al. 2008

Plasma Processes & Polymers

View full text Add to dashboard Cite

A mechanistic study is reported on i‐octane and hexane processing with +DC and −DC corona in air at room temperature and pressure. Current/voltage profiles are matched with the ion analysis data obtained by APCI mass spectrometry. With a −DC corona, the hydrocarbons do not modify the negative ion population with respect to uncontaminated air. In contrast, with a +DC corona many hydrocarbon‐derived positive ions form. O(3P) and •OH were also investigated using chemical probes (ozone formation and CO oxidation, respectively). The results, combined with efficiency and product data, suggest that with −DC corona radical initiation steps occur, whereas with +DC corona ionic reactions prevail.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

DC Corona Electric Discharges for Air Pollution Control, 2—Ionic Intermediates and Mechanisms of Hydrocarbon Processing

Marotta

Callea

Ren

et al. 2008

Plasma Processes & Polymers

View full text Add to dashboard Cite

show abstract

“…This obser-vation suggests that hydride abstraction from R ϩ might be an important route for [M Ϫ H] ϩ formation within atmospheric air plasmas. Specifically, hydride abstraction from i-octane is estimated to be exothermic for the major fragments observed, i.e., C 7 H 15 ϩ (⌬H r ϭ Ϫ39.9 kJ mol Ϫ1 [22,37]) and t-C 4 H 9 ϩ (⌬H r ϭ Ϫ62.1 kJ mol Ϫ1 [22,37,42]). …”

Section: Cyclohexanementioning

confidence: 99%

“…Thus, reaction with 2,4-dimethylpentane also produces C 4 H 10 NO ϩ , rather than the direct cleavage product C 3 H 8 NO ϩ , the 2-propyl cation/HNO complex. An additional proton transfer step (exothermic by 202.8 kJ mol Ϫ1 [37,42]) is required in this case to form the C 4 H 10 NO ϩ product ion (Scheme 4). Scheme 3.…”

Section: Cyclohexanementioning

confidence: 99%

A mass spectrometry study of alkanes in air plasma at atmospheric pressure

Marotta

Paradisi

2008

J. Am. Soc. Mass Spectrom.

View full text Add to dashboard Cite

The positive APCI-mass spectra in air of linear (n-pentane, n-hexane, n-heptane, n-octane), branched [2,4-dimethylpentane, 2,2-dimethylpentane and 2,2,4-trimethylpentane (i-octane)], and cyclic (cyclohexane) alkanes were analyzed at different mixing ratios and temperatures. The effect of air humidity was also investigated. Complex ion chemistry is observed as a result of the interplay of several different reagent ions, including atmospheric ions O 2 ϩ• , NO ϩ , H 3 O ϩ , and their hydrates, but also alkyl fragment ions derived from the alkanes. Some of these reactions are known from previous selected ion/molecule reaction studies; others are so far unreported. The major ion formed from most alkanes (M) is the species [M Ϫ H] ϩ , which is accompanied by M ϩ• only in the case of n-octane. Ionic fragments of C n H 2nϩ1 ϩ composition are also observed, particularly with branched alkanes: the relative abundance of such fragments with respect to that of [M Ϫ H] ϩ decreases with increasing concentration of M, thus suggesting that they react with M via hydride abstraction. The branched C 7 and C 8 alkanes react with NO ϩ to form a C 4 H 10 NO ϩ ion product, which upon collisional activation dissociates via HNO elimination. The structure of t-Bu ϩ (HNO) is proposed for such species, which is reasonably formed from the original NO ϩ (M) ion/molecule complex via hydride transfer and olefin elimination. . For air pollution control, different types of reactors and power supplies are being developed and tested for production of nonthermal plasmas by means of electrical discharges [3]. Following an initial phase devoted to prove the feasibility and competitiveness of the process in terms of energy and cost efficiency, research is presently focusing on the characterization of the chemistry-i.e., the products being released and the underlying chemical mechanisms-to develop a more efficient and cleaner process [5].In nonthermal plasmas, which are conveniently produced by electric corona discharges in air at atmospheric pressure, high-energy electrons induce ionization, excitation, and dissociation of the bulk gas molecules, N 2 and O 2 . The resulting reactive species, ionic and neutral as well as thermalized electrons, can attack molecules of organic pollutants present in the air, such as hydrocarbons and other volatile organic compounds (VOCs), and initiate a chain of reactions leading eventually to their oxidation. It is generally accepted that nonthermal plasma-induced VOC oxidation proceeds via VOC-derived organic radicals, R • , which are trapped by molecular oxygen and undergo further reactions as described for their tropospheric oxidation [6], leading eventually to CO 2 . As for the origin of such VOC-derived radicals, i.e., the nature of the initiation steps of nonthermal plasma-induced VOC decay, reactions of VOC molecules with neutrals and radicals, notably O( 3 P) and • OH, are usually envisioned. However, increasing numbers of literature reports suggest that in some cases ionic initiation steps might prevail [7][8][9...

show abstract

“…Therefore, one of the key links between combustion and plasma chemistry that remain are with ions, electrons, and excited species. Among ions, electrons and excited species, there has been some work on their effects in combustion systems, but the governing kinetics are weakly understood [23][24][25]. The hope is that the inclusion of ions, electrons, and excited species will open up the possibility of new and faster reaction pathways that can enhance critical combustion phenomena significantly with a high degree of chemical selectivity.…”

Section: Introductionmentioning

confidence: 99%

Flame propagation enhancement by plasma excitation of oxygen. Part II: Effects of O2(a1Δg)

Ombrello

Won

et al. 2010

Combustion and Flame

Self Cite

207

113

View full text Add to dashboard Cite

a b s t r a c tThe isolated effect of O 2 (a 1 D g ) on the propagation of C 2 H 4 lifted flames was studied at reduced pressures (3.61 kPa and 6.73 kPa). The O 2 (a 1 D g ) was produced in a microwave discharge plasma and was isolated from O and O 3 by NO addition to the plasma afterglow in a flow residence time on the order of 1 s. The concentrations of O 2 (a 1 D g ) and O 3 were measured quantitatively through absorption by sensitive off-axis integrated-cavity-output spectroscopy and one-pass line-of-sight absorption, respectively. Under these conditions, it was found that O 2 (a 1 D g ) enhanced the propagation speed of C 2 H 4 lifted flames. Comparison with the results of enhancement by O 3 found in part I of this investigation provided an estimation of 2-3% of flame speed enhancement for 5500 ppm of O 2 (a 1 D g ) addition from the plasma. Numerical simulation results using the current kinetic model of O 2 (a 1 D g ) over-predicts the flame propagation enhancement found in the experiments. However, the inclusion of collisional quenching rate estimations of O 2 (a 1 D g ) by C 2 H 4 mitigated the over-prediction. The present isolated experimental results of the enhancement of a hydrocarbon fueled flame by O 2 (a 1 D g ), along with kinetic modeling results suggest that further studies of C n H m + O 2 (a 1 D g ) collisional and reactive quenching are required in order to correctly predict combustion enhancement by O 2 (a 1 D g ). The present experimental results will have a direct impact on the development of elementary reaction rates with O 2 (a 1 D g ) at flame conditions to establish detailed plasma-flame kinetic mechanisms.

show abstract

Oxidation of Alkyl Ions, C_nH₂_n₊₁⁺ (n = 1−5), in Reactions with O₂ and O₃ in the Gas Phase

Cited by 10 publications

References 46 publications

DC Corona Electric Discharges for Air Pollution Control, 2—Ionic Intermediates and Mechanisms of Hydrocarbon Processing

DC Corona Electric Discharges for Air Pollution Control, 2—Ionic Intermediates and Mechanisms of Hydrocarbon Processing

A mass spectrometry study of alkanes in air plasma at atmospheric pressure

Flame propagation enhancement by plasma excitation of oxygen. Part II: Effects of O2(a1Δg)

Contact Info

Product

Resources

About