甲苯和对二甲苯在1050 ~ 1400k间与分子氧反应的动力学研究

Symposium (International) on Combustion Pub Date : 1998-01-01 DOI:10.1016/S0082-0784(98)80407-4

R.A. Eng , C. Fittschen , A. Gebert , P. Hibomvschi , H. Hippler , A.-N. Unterreiner

引用次数: 21

摘要

研究了甲苯与分子氧在反射激波下的反应。在1050 ~ 1400k的温度范围内，在2 ~ 4bar的总压力下，研究了0.5 ~ 1mol %甲苯和5 ~ 10%氧在氩气中的混合物。我们用时间分辨紫外吸收法在257 nm处跟踪了苯自由基的形成速度。用简单的反应机理数值再现了测量到的苯自由基的浓度-时间分布。对于初始反应c6h5ch3 +O2→C6H5CH2+HO2(R1)，速率系数k1为k1=3×1014exp[−180kj/molRT] cm3mools (1050K<T<1400K)，准确度为30%。测定了后续反应C6H5CH3+HO2→C6H5CH2+H2O2(R2)的反应速率常数k2为，k2=3×1014exp (- 92kj/molRT) cm3mol (1150K<T<1250K)。在氩气中，0.25-0.5 mol%的对二甲苯和2.5-10 mol%的氧的混合物被冲击加热到1130 - 1380 K之间。我们用时间分辨紫外吸收法在265 nm处观察对甲基苄基自由基的形成。然而，我们发现对甲基苄基自由基的产率很低，我们将其归因于这些自由基与分子氧的快速反应。根据这一低产率，我们估计了反应的速率常数k3/k4的上限为:p−CH3C6H4CH3+O2→p−CH3C6H4CH2+HO2(R3)p−CH3C6H4CH2+O2→p−CH2C6H4CH2+HO2(R4)。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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Kinetic investigations of the reactions of toluene and of p-xylene with molecular oxygen between 1050 and 1400 K

The reaction of toluene with molecular oxygen was studied behind reflected shock waves. Mixtures of 0.5–1 mol% toluene and 5–10% oxygen in argon were investigated in the temperature range between 1050 and 1400 K at total pressures between 2 and 4 bar. We followed the rate of formation of the benzyl radicals by time-resolved UV absorption at 257 nm. The measured concentration-time profiles of the benzyl radicals were numerically reproduced using a simple reaction mechanism. For the initial reaction $C_{6} H_{5} C H_{3} + O_{2} \to C_{6} H_{5} C H_{2} + H O_{2} (R 1)$ a rate coefficientk₁ of $k_{1} = 3 \times 10^{14} exp [\frac{- 180 kj / mol}{R T}] \frac{{cm}^{3}}{mol s} (1050 K < T < 1400 K)$ was determined with an accuracy of 30%. The rate constant k₂of the subsequent reaction $C_{6} H_{5} C H_{3} + H O_{2} \to C_{6} H_{5} C H_{2} + H_{2} O_{2} (R 2)$ was determined to be. $k_{2} = 3 \times 10^{14} exp [\frac{- 92 kj / mol}{R T}] \frac{{cm}^{3}}{mol s} (1150 K < T < 1250 K)$ The reaction of p-xylene with molecular oxygen was investigated using the same technique. Mixtures of 0.25–0.5 mol % p-xylene and 2.5–10 mol% oxygen in argon were shock-heated to temperatures between 1130 and 1380 K. We followed the formation of p-methyl-benzyl radicals by time-resolved UV absorption at 265 nm. However, we found a very low yield of p-methyl-benzyl radicals, which we attribute to a fast reaction of these radicals with molecular oxygen. From this low yield, we estimated for ratio k₃/k₄ of the rate constants for the reactions $\begin{matrix} p - C H_{3} C_{6} H_{4} C H_{3} + O_{2} \to p - C H_{3} C_{6} H_{4} C H_{2} + H O_{2} (R 3) \\ p - C H_{3} C_{6} H_{4} C H_{2} + O_{2} \to p - C H_{2} C_{6} H_{4} C H_{2} + H O_{2} (R 4) \end{matrix}$ an upper limit of 0.01..

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Symposium (International) on Combustion

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