Nascent Decomposition Pathways of CH 4 Pyrolysis in Gas-Phase Metal Halides.

We have performed a combined quantum mechanical and microkinetic modeling study to understand the nascent decomposition pathways of methane pyrolysis, catalyzed by gas-phase ZnCl ₂ , in a constant pressure batch reactor at 1273 K. We find that ZnCl ₂ catalyzes methane pyrolysis with an apparent activation energy of 227 kJ/mol. We have also performed sensitivity analysis on a reaction network comprising initiation, termination, and primary propagation reactions. The results suggest that the whole reaction network can be simplified to four reactions, which contributes to the initial rate of methane decomposition. Based on these insights, we have also explored the catalyzing effects of gas-phase AlCl ₃ , CoCl ₂ , CuCl ₂ , FeCl ₂ , and NiCl ₂ for methane decomposition. Our calculations suggest that gas-phase CuCl ₂ and NiCl ₂ are the most active catalysts among the metal halides studied in this work.