Experimental and modeling study of the oxidation of isobutene

This article describes an experimental and modeling study of the oxidation of isobutene. The low-temperature oxidation was studied in a continuous-flow stirred-tank reactor operated at constant temperature (from 833 to 913 K) and pressure (1 atm), with fuel equivalence ratios from 3 to 6 and space times ranging from 1 to 10 s corresponding to isobutene conversion yields from 1 to 50%. The main carbon containing products were analyzed by gas chromatography. The ignition delays of isobutene-oxygen-argon mixtures with fuel equivalence ratios from 1 to 3 were measured behind shock waves. Reflected shock waves permitted to obtain temperatures from 1230 to 1930 K and pressures from 9.5 to 10.5 atm. A mechanism has been proposed to reproduce the profiles obtained for the reactants consumption and the products formation during the slow oxidation and to compute the ignition delays in the shock tube. Simulations were performed using CHEMKIN II. A correct agreement between the simulated values and the experimental data has been obtained in both apparatuses. The main reaction paths have been determined for both series of measurements by a sensitivity and rate of production analysis. © 1998 John Wiley & Sons, Inc. Int J Chem Kinet 30: 629–640, 1998     

Experimental and modeling study of the oxidation of xylenes

This paper describes an experimental and modeling study of the oxidation of the three isomers of xylene (ortho‐, meta‐, and para‐xylenes). For each compound, ignition delay times of hydrocarbon–oxygen–argon mixtures with fuel equivalence ratios from 0.5 to 2 were measured behind reflected shock waves for temperatures from 1330 to 1800 K and pressures from 6.7 to 9 bar. The results show a similar reactivity for the three isomers. A detailed kinetic mechanism has been proposed, which reproduces our experimental results, as well as some literature data obtained in a plug flow reactor at 1155 K showing a clear difference of reactivity between the three isomers of xylene. The main reaction paths have been determined by sensitivity and flux analyses and have allowed the differences of reactivity to be explained. © 2006 Wiley Periodicals, Inc. Int J Chem Kinet 38: 284–302, 2006     

Experimental and modeling study of the oxidation of benzene

This paper describes an experimental and modeling study of the oxidation of benzene. The low‐temperature oxidation was studied in a continuous flow stirred tank reactor with carbon‐containing products analyzed by gas chromatography. The following experimental conditions were used: 923 K, 1 atm, fuel equivalence ratios from 1.9 to 3.6, concentrations of benzene from 4 to 4.5%, and residence times ranging from 1 to 10 s corresponding to benzene conversion yields from 6 to 45%. The ignition delays of benzene–oxygen–argon mixtures with fuel equivalence ratios from 1 to 3 were measured behind shock waves. Reflected shock waves permitted to obtain temperatures from 1230 to 1970 K and pressures from 6.5 to 9.5 atm. A detailed mechanism has been proposed and allows us to reproduce satisfactorily our experimental results, as well as some data of the literature obtained in other conditions, such as in a plug flow reactor or in a laminar premixed flame. The main reaction paths have been determined for the four series of measurements by sensitivity and flux analyses. © 2003 Wiley Periodicals, Inc. Int J Chem Kinet 35: 503–524, 2003     

Experimental and modeling study of the oxidation of toluene

This paper describes an experimental and modeling study of the oxidation of toluene. The low‐temperature oxidation was studied in a continuous flow stirred tank reactor with carbon‐containing products analyzed by gas chromatography under the following experimental conditions: temperature from 873 to 923 K, 1 bar, fuel equivalence ratios from 0.45 to 0.91, concentrations of toluene from 1.4 to 1.7%, and residence times ranging from 2 to 13 s corresponding to toluene conversion from 5 to 85%. The ignition delays of toluene–oxygen–argon mixtures with fuel equivalence ratios from 0.5 to 3 were measured behind reflected shock waves for temperatures from 1305 to 1795 K and at a pressure of 8.7 ± 0.7 bar. A detailed kinetic mechanism has been proposed to reproduce our experimental results, as well as some literature data obtained in other shock tubes and in a plug flow reactor. The main reaction paths have been determined by sensitivity and flux analyses. © 2004 Wiley Periodicals, Inc. Int J Chem Kinet 37: 25–49, 2005     

Experimental and modeling study of methyl cyclohexane pyrolysis and oxidation

Although the combustion chemistry of aliphatic hydrocarbons has been extensively documented, the oxidation of cyclic hydrocarbons has been studied to a much lesser extent. To provide a deeper understanding of the combustion chemistry of naphthenes, the oxidation of methylcyclohexane was studied in a series of high-temperature shock tube experiments. Ignition delay times for a series of mixtures, of varying methylcyclohexane/oxygen equivalence ratios (phi=0.5, 1.0, 2.0), were measured over reflected shock temperatures of 1200-2100 K and reflected shock pressures of 1.0, 2.0, and 4.0 atm. A detailed chemical kinetic mechanism has been assembled to simulate the shock tube results and flow reactor experiments, with good agreement observed.     

Experimental and chemical kinetic modeling study of 3-pentanone oxidation

Shock tube ignition delay times have been measured for 3-pentanone at a reflected shock pressure of 1 atm (±2%), in the temperature range 1250-1850 K, at equivalence ratios of 0.5-2.0 for O(2) mixtures in argon with fuel concentrations varying from 0.875 to 1.3125%. Laminar flame speeds have also been measured at an initial pressure of 1 atm over an equivalence ratio range. Complementary to previous studies [Pichon S., Black, G., Chaumeix, N., Yahyaoui, M., Simmie, J. M., Curran, H. J., Donohue, R. Combust. Flame, 2009, 156, 494-504; Serinyel, Z.; Black, G.; Curran, H. J.; Simmie, J. M. Combustion Sci. Tech., 2010, 182, 574-587], laminar flame speeds of 2-butanone have also been measured, and relative reactivities of these ketones have been compared and discussed. A chemical kinetic submechanism describing the oxidation of 3-pentanone has been developed and detailed in this paper; rate constants for unimolecular fuel decomposition reactions have been treated for falloff in pressure with nine-parameter fits using the Troe Formulism. Both compounds treated in this work may be used as fuel tracers, thus further ignition delay time measurements have been carried out by adding 3-pentanone to n-heptane in order to test the effect of the blend on ignition delay timing. It was found that the autoignition characteristics of n-heptane remained unaffected in the presence of 15% 3-pentanone in the fuel, consistent with results obtained using acetone and 2-butanone [Pichon S., Black, G., Chaumeix, N., Yahyaoui, M., Simmie, J. M., Curran, H. J., Donohue, R. Combust. Flame, 2009, 156, 494-504; Serinyel, Z.; Black, G.; Curran, H. J.; Simmie, J. M. Combustion Sci. Tech., 2010, 182, 574-587].     

Experimental and modeling study of shock‐tube oxidation of acetylene

Nine mixtures of acetylene and oxygen diluted in argon were studied behind reflected shock waves at temperatures of 1150–2132 K and pressures of 0.9–1.9 atm. Initial compositions were varied from very fuel‐lean to moderately fuel‐rich, covering equivalence ratios of 0.0625–1.66. Two more mixtures with added ethylene were used to boost the sensitivity to reactions of vinyl oxidation. The progress of reaction was monitored by laser absorption of CO molecules. The collected experimental data were subjected to extensive detailed chemical kinetics analysis. The initial kinetic model was assembled based on recent literature data and then optimized using the solution mapping technique. The analysis was extended to include recent experimental observations of Hidaka and co‐workers (Combust Flame 1996, 107, 401). The derived model reproduces closely both sets of experimental data, the result obtained by modifying nine rate coefficients and three enthalpies of formation of intermediate species. The identified parameter tradeoffs and justification for the changes are discussed. © 2003 Wiley Periodicals, Inc. Int J Chem Kinet 35: 391–414, 2003     

Experimental and kinetic modeling study of the oxidation of cyclopentane and methylcyclopentane at atmospheric pressure

Cyclopentane and methylcyclopentane oxidation was investigated in a jet-stirred reactor at atmospheric pressure, over temperatures ranging from 900 to 1250 K, for fuel-lean, stoichiometric, and fuel-rich mixtures at a constant residence time of 70 ms. The initial mole fraction of both fuels was kept constant at 1000 ppm. The reactants were highly diluted by a flow of nitrogen to ensure thermal homogeneity. Samples of the reacting mixture were analyzed online and off-line by Fourier transform infrared spectroscopy and gas chromatography. A detailed kinetic mechanism consisting of 590 species involved in 3469 reactions was developed, and simulation results were compared to these new experimental data and previously reported ignition delays. Reaction pathways analysis as well as sensitivity analyses were performed to get insights into the differences observed during the oxidation process of cyclopentane and methylcyclopentane.     

Experimental and modeling study of the oxidation of 1‐pentene at high temperature

Ignition delay times of 1‐pentene–oxygen–argon mixtures have been measured behind shock wave, the onset of ignition being detected by OH radical emission. Mixtures contained 1 or 2% of hydrocarbon for equivalence ratios ranging from 0.5 to 2. Reflected shock waves allowed temperatures from 1130 to 1620 K and pressures from 7.3 to 9.5 atm to be obtained. A detailed mechanism of combustion of 1‐pentene has been automatically generated using EXGAS software. This mechanism has been validated by comparing the results of the simulations to the experimental ignition delay times. The main reaction pathways have been derived from flow rate and sensitivity analyses at different temperatures. Comparisons with 1‐butene and 1‐hexene in the same conditions show that 1‐pentene has a higher reactivity which seems to be due to its decomposition to give ethyl radicals, which rapidly yields very reactive hydrogen atoms, while the decomposition of 1‐butene and 1‐hexene leads to less reactive methyl radicals. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 37: 451–463, 2005     

Homogeneous mono-and bimetallic catalysts for the oxidation of cyclohexene

In the absence of solvent, the first-row transition-metal acetylacetonate complexes and RuCl₂(PPh₃)₃ give fairly high turnovers for the allylic oxidation of cyclohexene under atmospheric pressure of oxygen. Synergetic effect is observed for the oxidation of cyclohexene by using M(acac)_n−RuCl₂(PPh₃)₃ bimetallic catalysts.     

Further study on the synthesis of F-containing porphyrins and their catalytic activity on oxidation of cyclohexene

Reaction of tetrakis(p-allyloxyphenyl)porphyrin and perfluoroalkanesulfonyl bromides givestetrakis(p-polyfluoroalkoxylphenyl)substituted porphyrins.The yields are over 90%.The synthesis ofthe metal ion complexes of these F-containing porphyrins is also reported.Preliminary results on thestudy of the catalytic activity of the manganese(Ⅲ)complexes of various fluorinated porphyrins onoxidation of cyclohexene indicate that the introduction of R_F group into porphyrin contributes to thestability of the catalysts.     

A comprehensive modeling study of hydrogen oxidation

A detailed kinetic mechanism has been developed to simulate the combustion of H₂/O₂ mixtures, over a wide range of temperatures, pressures, and equivalence ratios. Over the series of experiments numerically investigated, the temperature ranged from 298 to 2700 K, the pressure from 0.05 to 87 atm, and the equivalence ratios from 0.2 to 6. Ignition delay times, flame speeds, and species composition data provide for a stringent test of the chemical kinetic mechanism, all of which are simulated in the current study with varying success. A sensitivity analysis was carried out to determine which reactions were dominating the H₂/O₂ system at particular conditions of pressure, temperature, and fuel/oxygen/diluent ratios. Overall, good agreement was observed between the model and the wide range of experiments simulated. © 2004 Wiley Periodicals, Inc. Int J Chem Kinet 36: 603–622, 2004     

Shock-tube and modeling study of chloroethane pyrolysis and oxidation

The high-temperature pyrolysis and oxidation of chloroethane were studied behind reflected shock waves using single-pulse, time-resolved IR absorption (3.39 μm), time-resolved UV absorption (306.7 nm), and time-resolved IR emission (4.24 μm) methods. The studies were performed over the temperature range 900–1650 K at total pressures between 0.8 and 3.2 atm. From a computer simulation study, a 201-reaction mechanism that could explain all of our data was constructed. The reactions at high temperatures were discussed in detail. It was found that, in the chloroethane pyrolysis and oxidation under our experimental conditions, reactions (1)–(7) and (9) and the submechanism of ethylene were important to predict our data. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 40: 320–339, 2008     

Experimental and modeling study of the oxidation of 1‐butyne and 2‐butyne

Ignition delays were measured behind shock waves in the cases of hydrocarbon–oxygen–argon mixtures containing 1‐butyne or 2‐butyne (1 or 2% of hydrocarbons for equivalence ratios from 0.5 to 2). Reflected shock waves permitted to obtain temperatures from 1100 to 1600 K and pressures from 6.3 to 9.1 atm. A detailed mechanism of the reactions of 1‐butyne and 2‐butyne has been explained in the line of the mechanism developed previously for the reaction of C₃–C₄ unsaturated hydrocarbons (propyne, allene, 1,3‐butadiene) [Int J chem Kin 1999, 31, 361]. It is based on the most recent kinetic data values published in the literature and is consistent with thermochemistry. This mechanism has been validated by comparing the results of our simulations to the experimental results obtained for ignition delays in our shock tube and to measurements of species obtained during thermal decomposition [Int J Chem Kin 1995, 27, 321; J Phys Chem 1993, 97, 10977]. The main reaction pathways have been derived from flow‐rate and sensitivity analyses. © 2002 Wiley Periodicals, Inc. Int J Chem Kinet 34: 172–183, 2002; DOI 10.1002/kin.10035     

环己烯可控选择性催化氧化的最新进展（英文）

环己烯是一种价格低廉易得的大宗化工原料,通常由苯选择性加氢来合成.该化合物虽然分子结构简单,但却有两个不同的反应位点.随着反应所发生的位点与反应深度的不同,环己烯的氧化反应可生成一系列不同氧化程度与官能团的产物的混合物.环己烯双键的氧化反应,可生成环氧环己烷,而环氧环己烷进一步水解,则生成1,2-环己二醇,其中,随着使用不同催化剂导致的反应机理差异,产物可分别为顺式或反式结构.在强氧化剂作用下,环己烯双键充分氧化,可生成己二酸.环己烯烯丙基C-H键氧化,则可随着反应深度的不同分别生成2-环己烯醇与2-环己烯酮.上述环己烯氧化产物都是重要的有机化工中间体.其中,环氧环己烷是农药杀螨剂的主要原料,也用作合成表面活性剂、橡胶助剂等有用产品;1,2-环己二醇可用于合成化工中间体邻苯二酚;环己烯醇与环己烯酮是生产除草剂、香水、药物的原料;己二酸则是合成重要产品尼龙-6,6的原料.因此,随着市场需求的变化,对环己烯氧化反应进行选择性控制,提高其中某种产物的选择性,是重要的化工合成技术,有着巨大的应用潜力;从而控制反应历程与深度是有机化工合成工艺研究中最具有挑战性的研究课题之一,有很好的科学意义.目前,人们对环己烯的选择性控制氧化反应已进行了广泛的研究.该反应可使用金属催化剂,包括铁、钴、镍、锰、铬、钒、钨、铜、钛、金、银、铋、锇、钼、镉等;也可以使用无金属催化剂如磺酸、2,2,2-三氟苯乙酮、类石墨相碳化氮(g-C3N4)等.反应可使用化学氧化剂,如间氯过氧苯甲酸、醋酸碘苯、过氧叔丁醇等,也可使用更加清洁的过氧化氢、分子氧.研究表明,催化剂的种类、用量,以及反应溶剂、温度、氧化剂等一系列外在条件,可以影响环己烯氧化反应的选择性.本文以反应所使用的氧化剂归类,总结了该课题的最新研究进展,以期对从事环己烯可控选择性氧化的学术与工业研究人员有所帮助.     

Experimental and modeling study of the autoignition of cyclopentene

Ignition delay times of cyclopentene–oxygen–argon mixtures were measured behind reflected shock waves. Mixtures contained 0.5% or 1% of hydrocarbons for equivalence ratios ranging from 0.5 to 1.5. Reflected shock wave conditions were as follows: temperatures from 1300 to 1700 K and pressures from 7 to 9 atm. When compared with the previous results obtained under similar conditions, it can be observed that the reactivity of cyclopentene is much lower than that of cyclohexene, but very close to that of cyclopentane. A kinetic mechanism recently proposed for the combustion of cyclopentene in a flame has been used to model these results, and a satisfactory agreement is obtained. The main reaction pathways have been derived from the flow rate, simulated temporal profiles of products, and sensitivity analyses. © 2007 Wiley Periodicals, Inc. Int J Chem Kinet 40: 25–33, 2008     

Experimental and modeling study of ice melting

Differential scanning calorimetry (DSC) is applied to analyse the process of ice melting. Experimental results were compared to those obtained by a numerical simulation in which a conventional enthalpy formulation was applied. The effects of various parameters on the kinetics of transformations and therefore the shape of curves has been analysed and the importance of temperature gradients inside the sample evaluated.