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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Kinetics of the Methyl-Vinyl Radical + O-2 Reactions Associated with Propene Oxidation
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Kinetics of the Methyl-Vinyl Radical + O-2 Reactions Associated with Propene Oxidation

机译：与丙烯氧化相关的甲基乙烯基自由基+ O-2反应的动力学

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摘要

The bimolecular rate coefficients of reactions CH3CCH2 + O-2 (1) and cis/trans-CH3CHCH + O-2 (2a/3a) have been measured using a tubular laminar flow reactor coupled with a photoionization mass spectrometer (PIMS). These reactions are relevant in the combustion of propene. Pulsed excimer laser photolysis of a ketone or a bromide precursor molecule at 193 or 248 nm wavelength was used to produce radicals of interest homogeneously along the reactor. Time-resolved experiments were performed under pseudo-first-order conditions at low pressure (0.3-1.5 Torr) over the temperature range 220-660 K. The measured bimolecular rate coefficients were found to be independent of bath gas concentration. The bimolecular rate coefficients possess negative temperature dependence at low temperatures (T 420 K) and appear to be independent of temperature at high temperatures (T 420 K). Observed products of the reaction CH3CCH2 + O-2 were CH3 and H2CO, while for the reaction cis/trans-CH3CHCH + O-2, observed products were CH3CHO and HCO. Current results indicate that the reaction mechanism of both reactions is analogous to that of C2H3 + O-2. Methyl substitution of the vinyl radical changes its reactivity toward O-2 upward by ca. 50% if it involves the alpha-position and downward by ca. 30% if the methyl group takes either of the beta-positions, respectively.
机译：反应的双分子率系数CH 3 CCH 2 + O-2（1）和CIS / TRAN-CH3CHCH + O-2（2A / 3A）已经使用与光离子型质谱仪（PIMS）耦合的管状层状流量反应器来测量。这些反应在丙烯的燃烧中是相关的。在193或248nm波长下使用酮的脉冲准分子激光光解或溴化物前体分子用于沿反应器均匀地产生感兴趣的自由基。在低压（0.3-1.5托）上在220-660k的低压（0.3-1.5托）下在伪第一阶条件下进行时间分辨实验。发现测量的双分子率系数与浴气体浓度无关。双分子率系数在低温下具有负温度依赖性（T <420 k），并且似乎与高温下的温度无关（T＆ 420 k）。观察到的反应产物CH 3 CCH 2 + O-2是CH 3和H 2 CO，而对于反应CIS / TREN-CH3CHCH + O-2，观察产物是CH3CHO和HCO。目前的结果表明，两种反应的反应机理类似于C 2 H 3 + O-2的反应机理。乙烯基的甲基取代改变其对o-2向上的反应性。如果它涉及Alpha-Location和Down By Ca.如果甲基分别服用β位置，则30％。

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