Shock-tube study of methane pyrolysis in the context of energy-storage processes

Abstract

Abstract The thermal decomposition of methane (10\u202f mol% in inert gases) was investigated behind reflected shock waves. Product spectra were measured via GC/MS after reactions with initial temperatures between 1285 and 2400\u202fK at pressures of 1.5\u202fbar in a single-pulse shock tube and of 30\u202fbar in a high-pressure shock tube with rapid gas sampling via a fast opening valve. In the 1.5-bar experiments, additional time-resolved absorption measurements in the mid-IR were carried out. The temporal variation in CH 4 concentration was measured at 836–2495\u202fK and 1.8\u202fbar with interband-cascade lasers near 3.39\u202fµm. Time-resolved temperatures were determined via CO two-line thermometry with two quantum-cascade lasers near 4.56 and 4.85\u202fµm for initial post-shock temperatures of 1715–2573\u202fK at 2.2\u202fbar. The results were compared to simulations based on three different literature mechanisms (Cai and Pitsch, 2015; Porras et al., 2017; Wang et al., 2007) as well as with the new rate constant of methane dissociation from Wang et al. (2016).