Pressure-Dependent Competition among Reaction Pathways from First- and Second-O2 Additions in the Low-Temperature Oxidation of Tetrahydrofuran

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• 作者：Ivan O. Antonov ; Judit Zádor ; Brandon Rotavera ; Ewa Papajak ; David L. Osborn ; Craig A. Taatjes ; Leonid Sheps
• 刊名：Journal of Physical Chemistry A
• 出版年：2016
• 出版时间：August 25, 2016
• 年：2016
• 卷：120
• 期：33
• 页码：6582-6595
• 全文大小：697K
• 年卷期：0
• ISSN：1520-5215

文摘

We report a combined experimental and quantum chemistry study of the initial reactions in low-temperature oxidation of tetrahydrofuran (THF). Using synchrotron-based time-resolved VUV photoionization mass spectrometry, we probe numerous transient intermediates and products at P = 10–2000 Torr and T = 400–700 K. A key reaction sequence, revealed by our experiments, is the conversion of THF-yl peroxy to hydroperoxy-THF-yl radicals (QOOH), followed by a second O₂ addition and subsequent decomposition to dihydrofuranyl hydroperoxide + HO₂ or to γ-butyrolactone hydroperoxide + OH. The competition between these two pathways affects the degree of radical chain-branching and is likely of central importance in modeling the autoignition of THF. We interpret our data with the aid of quantum chemical calculations of the THF-yl + O₂ and QOOH + O₂ potential energy surfaces. On the basis of our results, we propose a simplified THF oxidation mechanism below 700 K, which involves the competition among unimolecular decomposition and oxidation pathways of QOOH.