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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Pyrolysis mechanisms of thiophene and methylthiophene in asphaltenes
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Pyrolysis mechanisms of thiophene and methylthiophene in asphaltenes

机译：噻吩和甲基噻吩在沥青质中的热解机理

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The pyrolysis mechanisms of thiophene in asphaltenes have been investigated theoretically using density functional and ab initio quantum chemical techniques. All of the possible reaction pathways were explored using B3LYP, MP2, and CBS-QB3 models. A comparison of the calculated heats of reaction with the available experimental values indicates that the CBS-QB3 level of theory is quantitatively reliable for calculating the energetic reaction paths of the title reactions. The pyrolysis process is initiated via four different types of hydrogen migrations. According to the reaction barrier heights, the dominant 1,2-H shift mechanism involves two competitive product channels, namely, C _2H_2 + CH_2CS and CS + CH_3CCH. The minor channels include the formation of CS + CH_2CCH_2, H_2S + C_4H_2, HCS + CH_2CCH, CS + CH_2CHCH, H + C_4H_3S, and HS + C _4H_3. The methyl substitution effect was investigated with the pyrolysis of 2-methylthiophene and 3-methylthiophene. The energetics of such systems were very similar to that for unsubstituted thiophene, suggesting that thiophene alkylation may not play a significant role in the pyrolysis of asphaltene compounds.
机译：理论上已经使用密度泛函和从头算量子化学技术研究了噻吩在沥青质中的热解机理。使用B3LYP，MP2和CBS-QB3模型探索了所有可能的反应途径。计算出的反应热与可用的实验值的比较表明，CBS-QB3理论水平对于计算标题反应的高能反应路径在定量上是可靠的。热解过程是通过四种不同类型的氢迁移引发的。根据反应势垒高度，主要的1,2-H转移机理涉及两个竞争产物通道，即C _2H_2 + CH_2CS和CS + CH_3CCH。次要通道包括CS + CH_2CCH_2，H_2S + C_4H_2，HCS + CH_2CCH，CS + CH_2CHCH，H + C_4H_3S和HS + C _4H_3的形成。通过2-甲基噻吩和3-甲基噻吩的热解研究了甲基取代作用。这种系统的能量学与未取代的噻吩的非常相似，这表明噻吩烷基化可能在沥青质化合物的热解中不发挥重要作用。

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