摘要:

AbstractThe gas‐phase reaction of ozone with C5C10alkenes(eight 1‐alkenes, four 1,1‐disubstituted alkenes, and cyclohexene) has been investigated at atmospheric pressure and ambient temperature (285–293 K). Cyclohexane was added to scavenge the hydroxyl radical, which forms as a product of the ozone‐alkene reaction. The reaction rate constants, in units of 10−18cm3molecule−1s−1, are 9.6±1.6 for 1‐pentene, 9.7±1.4 for 1‐hexene, 9.4±0.4 for 1‐heptene, 12.5±0.4 for 1‐octene, 8.0±1.4 for 1‐decene, 3.8±0.6 for 3‐methyl‐1‐pentene, 7.3±0.7 for 4‐methyl‐1‐pentene, 3.9±0.9 for 3,3‐dimethyl‐1‐butene, 13.3±1.4 for 2‐methyl‐1‐butene, 12.5±1.1 for 2‐methyl‐1‐pentene, 10.0±0.3 for 2,3‐dimethyl‐1‐butene, 13.7±0.9 for 2‐ethyl‐1‐butene, and 84.6±1.0 for cyclohexene. Substituent effects on alkene reactivity are examined. Steric effect appear to be important for all 1,1‐disubstituted alkenes as well as for those 1‐alkenes that bears‐butyl andt‐butyl groups. The results are briefly discussed with r

ISSN:0538-8066    

DOI:10.1002/kin.550271102

出版商:John Wiley&Sons, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe oxidation kinetics of malic acid by vanadium(V) in aqueous sulphuric acid was investigated at 303 K by monitoring the appearance of vanadium(IV) at 760 nm. The reaction showed first‐order behavior with respect to vanadium(V), malic acid, and hydrogen ion concentration, respectively, regardless of the ionic strength. The reaction rate is enhanced by an increase in ionic strength and a decrease of the dielectric constant of the medium by addition of methanol. The activation parameters were estimated by varying the temperature in the range of 293 K to 313 K to 313 K. An oxidation mechanism is proposed, involving different vanadium(V) species produced in the presence of sulphuric acid. © 1995 John Wiley&Sons, I

ISSN:0538-8066    

DOI:10.1002/kin.550271103

出版商:John Wiley&Sons, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractSynthesis of ethyl tert‐butyl ether (ETBE) from ethanol (EtOH) and tert‐butyl alcohol (TBA) in the liquid phase was studied by using ion exchange resin, Amberlyst 15 (A15) in the H+form and heteropoly acid, H0.5Cs3.5SiW12O40(HPA). Experiments were carried out in a stirred batch reactor with different temperatures under atmospheric pressure. It was found that water will inhibit the reaction rates greatly and the dehydration of TBA could not be neglected in this study.A kinetics model which considered the inhibition of water and the decrease of volume was proposed. The experimental results agreed well with the model. © 1995 John Wiley&Sons,

ISSN:0538-8066    

DOI:10.1002/kin.550271104

出版商:John Wiley&Sons, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractSimultaneous, quantitative, narrow‐line laser absorption measurements of CN time‐histories at 388.444 nm and OH time‐histories at 306.687 nm have been made in incident and reflected shock wave experiments using dilute mixtures of nitiric acid (HNO3) and HCN in argon. The thermal decomposition of HNO3serves as a rapid source of OH upon shock‐heating, and the OH subsequently reacts predominantly with the HCN in the test gas mixture. The rate coefficient for the reactionwas determined in the temperature range 1120–1960 K via detailed kinetics modeling of the simultaneously acquired CN and OH measurements. These data are in good agreement with lower temperature measurements of the rate of the reverse reaction (−1a) when recent values of the heats of formation of CN and HCN are used. The expression\documentclass{article}\pagestyle{empty}\begin{document}$$ k_{1a} \, = \,3.90\, \times \,10^6 T^{1.83} \exp (- 5179/T)cm^3 mol^{ - 1} s^{ - 1}, $$\end{document}valid for temperatures 500 to 2000 K, effectively represents the experimental measurements. The estimated uncertainty of the expression fork1ais ±30%, based on the experimental uncertainties of the individual rate coefficient studies. Analysis of the decay region of the experimental OH time‐histories yielded the total rate coefficientk1(all product channels) for the reaction of HCN with OH for temperatures ranging from 1490 to 1950 K. These measurements are consistent with a previous theoretical analysis of the three primary addition‐isomerization‐dissociation processes for the HCN + OH reaction at combustion temperatures when the contribution tok1from reaction (1a) is included. © 1995 J

ISSN:0538-8066    

DOI:10.1002/kin.550271105

出版商:John Wiley&Sons, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractLiquid CO2sequestration in a bathymetric depression at depths greater than 3700 m in the ocean has been proposed as a mitigation strategy for the reduction of atmospheric CO2emissions. Kinetic studies on the dissolution of CO2from the liquid CO2pool, the diffusion in the ocean, and advection of CO2by the bottom ocean current are carried out. A thin membrane of CO2hydrate on the liquid CO2pool controls the CO2dissolution into the overlaying seawater, the thickness of a static layer between the surface of liquid CO2and the upper bottom ocean current reduces the CO2diffusion, and the bottom ocean current dilutes the CO2concentration. These effects are explicity formulated in an equation, and it is predicted that ocean CO2sequestration at a depth larger than 3700 m will greatly reduce the pH change caused by CO2dispersion in the ocean. © 1995 John Wiley&Sons, Inc

ISSN:0538-8066    

DOI:10.1002/kin.550271106

出版商:John Wiley&Sons, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractWe propose a new high temperature pathway for NO formation that involves the reaction of NNH with oxygen atoms. This reaction forms the HNNO* energized adduct via a rapid combination reaction; HNNO* then rapidly dissociates to NH + NO. The rate constant for O + NNH  NH + NO is calculated via a QRRK chemical activation analysis to be 3.3 × 1014T−0.23exp(+510/T) cm3mol−1s−1. This reaction sequence can be an important or even major route to NO formation under certain combustion conditions. The presence of significant quantities of NNH results from the reaction of H with N2. The H + N2 NNH reaction is only ca. 6 kcal/mol endothermic with a relatively low barrier. The reverse reaction, NNH dissociation, has been reported in the literature to be enhanced by tunneling. Our analysis of NNH dissociation indicates that tunneling dominates. We report a two‐term rate constant for NNH dissociation: 3.0 × 108+ [M] {1.0 × 1013T0.5exp(−1540/T)} s−1. The first term accounts for pressure‐independent tunneling from the ground vibrational state, while the second term accounts for collisional activation to higher vibration states from which tunneling can also occur. ([M] is the total concentration in units of mol cm−3.) Use of this dissociation rate constant and microscopic reversibility results in a large rate constant for the H + N2reaction. As a result, we find that NNH  H + N2can be partially equilibrated under typical combustion conditions, resulting in NNH concentrations large enough for it to be important in bimolecular reactions. Our analysis of such reactions suggests that the reaction with oxygen atoms is especially important. ©

ISSN:0538-8066    

DOI:10.1002/kin.550271107

出版商:John Wiley&Sons, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe rate coefficients of the reactions of NCO radicals with NO and NO2: (1) NCO + NO → products (293–836 K) and : (2) NCO + NO2→ products (294–774 K) were measured by means of laser photolysis and laser induced fluorescence technique in the indicated temperature ranges. NCO radicals were produced from the reaction of CN, from photodissociation of ICN or BrCN, with O2. The concentration of NCO was monitored with a dye laser set at 414.95 nm. We determinedk1= 1.73 × 10−5T−2.01exp(−470/T) cm3molecule−1s−1that agrees with published results at room temperature and confirms the temperature dependence of an early report. A non‐Arrhenius negative temperature dependence ofk2was observed in this work that agrees satisfactorily with results for a shock tube18near 1250 K. We obtainedk2= 6.4 × 10−10T−0.646exp(164/T) cm3molecule−1s−1for 1250 K ≥T≥ 294 K by combining data of these two measurements. Our result at 294 K and the temperature dependence disagree with results of two previous investigat

ISSN:0538-8066    

DOI:10.1002/kin.550271108

出版商:John Wiley&Sons, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe kinetics of C2H5O2and C2H5O2radicals with NO have been studied at 298 K using the discharge flow technique coupled to laser induced fluorescence (LIF) and mass spectrometry analysis. The temporal profiles of C2H5O were monitored by LIF. The rate constant for C2H5O + NO → Products (2), measured in the presence of helium, has been found to be pressure dependent:k2= (1.25±0.04) × 10−11, (1.66±0.06) × 10−11, (1.81±0.06) × 10−11at P (He) = 0.55, 1 and 2 torr, respectively (units are cm3molecule−1s−1). The Lindemann‐Hinshelwood analysis of these rate constant data and previous high pressure measurements indicates competition between association and disproportionation channels: C2H5O + NO + M → C2H5ONO + M (2a), C2H5O + NO → CH3CHO + HNO (2b). The following calculated average values were obtained for the low and high pressure limits ofk2aand fork2b:k 2a0= (2.6±1.0) × 10−28cm6molecule−2s−1,k 2ax= (3.1±0.8) × 10−11cm3molecule−1s−1andk2bca. 8 × 10−12cm3molecule−1s−1. The present value ofk 2a0, obtained with He as the third body, is significantly lower than the value (2.0±1.0) × 10−27cm6molecule−2s−1recommended in air. The rate constant for the reaction C2H5O2+ NO → C2H5O + NO2(3) has been measured at 1 torr of He from the simulation of experimental C2H5O profiles. The value obtained fork3= (8.2±1.6) × 10−12cm3molecule−1s−1is in good agreement with pre

ISSN:0538-8066    

DOI:10.1002/kin.550271109

出版商:John Wiley&Sons, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractAn economical postprocessing method for estimating feature sensitivity coefficients is presented. This method uses precomputed elementary sensitivity coefficients calculated by standard methods to obtain a perturbed solution using a linear approximation to the Taylor series expansion. The perturbed solution is then used for simple feature sensitivity calculations. This approach avoids costly repetitive integrations for each model parameter and can be readily implemented with available computer codes which solve for species profiles and elementary sensitivities. The method was tested using a practical example of a CH flame profile and shown to be in good agreement with a brute‐force sensitivity analysis performed for the same conditions. It is also suggested that the method can be readily extended to simultaneous sensitivity analysis of multiple responses or to sensitivity analysis with respect to a functional combination of model parameters. © 1995 John Wiley&Sons, I

ISSN:0538-8066    

DOI:10.1002/kin.550271110

出版商:John Wiley&Sons, Inc.    

年代:1995

数据来源: WILEY

ISSN:0538-8066    

DOI:10.1002/kin.550271101

出版商:John Wiley&Sons, Inc.    

年代:1995

数据来源: WILEY