Kinetic assessment of supercritical methylcyclohexane dehydrogenation: Experimental and CFD modeling

To address hypersonic vehicle thermal management via endothermic dehydrogenation, this work studies methylcyclohexane (MCH) dehydrogenation kinetic over Pt/SiO₂ under supercritical conditions. Power-law modeling shows a near-zero MCH order, with hydrogen promoting cracking and isomerization. A Langmuir-Hinshelwood-Hougen-Watson (LHHW) model accurately describes dehydrogenation and cracking (R² > 0.95), identifying the first H₂ loss and surface reaction as their respective rate-determining steps, but fails for isomerization. An optimal hybrid LHHW/power-law model for dehydrogenation and side-reactions (R² = 0.97, MSE < 10^–5) is developed. CFD simulations using this kinetics reveal radial temperature gradients exceeding axial variations, intensifying at high wall temperatures. Cold spot position depends primarily on space velocity, while its temperature responds mainly to wall heating. This advances optimization strategies for catalytic reactors and thermal management.