Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.
Department of Civil, Chemical, Environmental, and Materials Engineering (DICAM), Alma Mater Studiorum, University of Bologna, Bologna 40126, Italy.
J Phys Chem A. 2023 Apr 13;127(14):3231-3245. doi: 10.1021/acs.jpca.2c07545. Epub 2023 Mar 31.
The combustion and pyrolysis behaviors of light esters and fatty acid methyl esters have been widely studied due to their relevance as biofuel and fuel additives. However, a knowledge gap exists for midsize alkyl acetates, especially ones with long alkoxyl groups. Butyl acetate, in particular, is a promising biofuel with its economic and robust production possibilities and ability to enhance blendstock performance and reduce soot formation. However, it is little studied from both experimental and modeling aspects. This work created detailed oxidation mechanisms for the four butyl acetate isomers (normal-, sec-, tert-, and iso-butyl acetate) at temperatures varying from 650 to 2000 K and pressures up to 100 atm using the Reaction Mechanism Generator. About 60% of species in each model have thermochemical parameters from published data or in-house quantum calculations, including fuel molecules and intermediate combustion products. Kinetics of essential primary reactions, retro-ene and hydrogen atom abstraction by OH or HO, governing the fuel oxidation pathways, were also calculated quantum-mechanically. Simulation of the developed mechanisms indicates that the majority of the fuel will decompose into acetic acid and relevant butenes at elevated temperatures, making their ignition behaviors similar to butenes. The adaptability of the developed models to high-temperature pyrolysis systems was tested against newly collected high-pressure shock experiments; the simulated CO mole fraction time histories have a reasonable agreement with the laser measurement in the shock tube. This work reveals the high-temperature oxidation chemistry of butyl acetates and demonstrates the validity of predictive models for biofuel chemistry established on accurate thermochemical and kinetic parameters.
由于轻酯和脂肪酸甲酯作为生物燃料和燃料添加剂的相关性，它们的燃烧和热解行为已经得到了广泛的研究。然而，对于中链烷基醋酸酯，特别是具有长烷氧基的那些，仍然存在知识空白。乙酸丁酯是一种很有前途的生物燃料，具有经济和强大的生产可能性，能够提高调合料的性能并减少烟尘的形成。然而，从实验和建模两方面来看，对其研究都很少。本工作使用反应机理生成器，针对正丁酯、仲丁酯、叔丁酯和异丁酯这四种乙酸丁酯异构体，在 650 到 2000 K 的温度范围和高达 100 大气压的压力下，创建了详细的氧化机理。每个模型中约有 60%的物种具有来自已发表数据或内部量子计算的热化学参数，包括燃料分子和中间燃烧产物。对控制燃料氧化途径的基本主反应、反烯和 OH 或 HO 夺取氢原子的动力学也进行了量子力学计算。所开发的机理模拟表明，在高温下，大部分燃料将分解为乙酸和相关的丁烯，使其点火行为类似于丁烯。开发模型对高温热解系统的适应性通过与新收集的高压激波实验进行了测试；在激波管中，模拟的 CO 摩尔分数时间历程与激光测量具有合理的一致性。这项工作揭示了乙酸丁酯的高温氧化化学，并证明了基于准确热化学和动力学参数建立的生物燃料化学预测模型的有效性。
