Abstract Isoprenoids have been synthesized in large quantities through metabolic engineering method using some microorganisms as hosts and biomass as carbon resources. An isoprenoid cyclic hydrocarbon, p-menthane, is considered as a promising “drop-in” fuel to substitute traditional cycloalkane components, however, its pyrolysis data is lacking so far which is a significant part of the fuel combustion chemistry, especially under high pressures. In this work, pyrolysis experiments of p-menthane were carried out in a tandem micro-reactor under temperature of 450–800 °C and pressure of 2 MPa. 39 species were identified and quantified by online GC–MS/FID, based on which some initial pyrolysis pathways were determined. The early production of 4-methyl-1-cyclohexene and 1-isopropyl-1-cyclohexene indicates that methyl and isopropyl scission happen at the initial stage followed by H-transfer reaction and dehydrogenation. The activation energy Ea and pre-exponential factor A of the overall reaction were calculated as 225 kJ mol−1 and 1.17 × 1012 s−1, respectively. For secondary reactions, many conjugated dienes such as 1,3-butadiene and 2-methyl-1,3-butadiene and small olefins such as ethylene and propene are generated through the ring-opening pathways. Benzene and toluene are the most abundant products among aromatics detected which are formed through dehydrogenation and demethylation of some early species like 4-methyl-1-cyclohexene and side-chain scission of aromatics. A particular product 1,3-hexadien-5-yne was detected which is generated through ring-opening pathways followed by H-transfer and demethylation reactions and could isomerized to benzene. A lumped kinetic model was proposed to describe the pyrolysis of p-menthane which exhibited good agreement with the experimental data.

中文翻译：

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使用在线 GC-MS/FID 在串联微反应器中高压热解类异戊二烯烃对薄荷烷

摘要 以某些微生物为宿主，生物质为碳资源，通过代谢工程方法大量合成了类异戊二烯。类异戊二烯环烃对薄荷烷被认为是替代传统环烷烃组分的有前途的“插入式”燃料，然而，迄今为止缺乏其热解数据，这是燃料燃烧化学的重要组成部分，尤其是在高压下. 在这项工作中，对薄荷烷的热解实验在串联微反应器中进行，温度为 450-800 °C，压力为 2 MPa。通过在线 GC-MS/FID 鉴定和量化了 39 种物质，在此基础上确定了一些初始热解途径。4-甲基-1-环己烯和1-异丙基-1-环己烯的早期生产表明甲基和异丙基断裂发生在初始阶段，随后发生H-转移反应和脱氢。整个反应的活化能 Ea 和指前因子 A 分别计算为 225 kJ mol-1 和 1.17 × 1012 s-1。对于二次反应，许多共轭二烯（如 1,3-丁二烯和 2-甲基-1,3-丁二烯）和小烯烃（如乙烯和丙烯）通过开环途径生成。苯和甲苯是检测到的芳烃中含量最丰富的产物，它们是通过一些早期物种（如 4-甲基-1-环己烯）的脱氢和去甲基化以及芳烃的侧链断裂形成的。一个特定的产品 1, 检测到 3-己二烯-5-炔，它是通过开环途径产生的，然后是氢转移和去甲基化反应，可以异构化为苯。提出了一个集总动力学模型来描述对薄荷烷的热解，该模型与实验数据非常吻合。