Insight into the high-temperature oxidation kinetics of acetylene: A first-principles molecular dynamics study

The study on high-temperature oxidation kinetics and kinetic modeling of acetylene (C₂H₂) has significant importance for its engineering applications. In this paper, the first-principles molecular dynamics method is used to simulate the C₂H₂ oxidation under high temperatures for the first time. Our results show that there are 38 intermediates and 225 elementary reactions in the process of C₂H₂ oxidation. The formation mechanisms of "prompt" CO₂, as well as gas pollutants CHOCHO and HCOOH are revealed in depth. Four intermediates, CHCHO, CHOCO, CHOCHO and HCOOH, which have significant controversy in current kinetic models, are verified. And a new intermediate, CHOCO₂, is discovered. Meanwhile, our simulation also shows that radicals, such as HO₂, OH, O, etc. play a key role in promoting the oxidation of intermediates in the early stage of C₂H₂ oxidation. Combined with quantum chemical calculations, a detailed chemical kinetic model of C₂H₂/air (FP-C₂H₂) is built and verified by simulating ignition delay time, species concentration in the flow reactor and premixed laminar flame speed. Our studies provide novel insight for understanding the complex chemical reaction kinetics, and environmental and human health threats from air pollutant formation during C₂H₂ combustion.