Numerical modeling of n -hexane pyrolysis with an optimized kinetic mechanism in a hydrogen plasma reactor

Abstract The physicochemical mechanisms underlying the pyrolysis of n -hexane in a high temperature Ar-H 2 environment were investigated for a plasma pyrolysis process. An optimal chemical kinetics model was developed using the Reaction Mechanism Generator, an automated tool for constructing reaction mechanisms. This model was validated through 0-D analyses, where simulation results were compared with existing kinetic models (LLNL, JetSurf) and experimental data from conventional n -hexane pyrolysis. Subsequently, 1-D analyses were conducted to identify the optimal operational flow rate in the plasma pyrolysis reactor, the results of which informed detailed axisymmetric 2-D computational fluid dynamics (CFD) modeling of the plasma reactor. The CFD simulations reveal that fluid mixing dynamics play a dominant role in determining the extent of conversion and product selectivity, highlighting the limitations of lower-dimensional models in capturing essential transport phenomena. Notably, the simulations indicate a higher C 2 monomer selectivity of approximately 50% under plasma-based n -hexane pyrolysis, in contrast to the roughly 30% selectivity achieved via conventional fossil-fuel-based methods. These findings underscore the potential advantages of plasma-driven pyrolysis and represent a critical step toward a comprehensive understanding of the complex thermochemical behavior governing plasma-assisted processes.