Extension to multiple temperatures of a three-reaction global kinetic model for methane dehydroaromatization

An alternative to flaring of surplus natural gas is methane dehydroaromatization (MDA) to benzene (C₆H₆) over a bifunctional molybdenum/zeolite catalyst. Byproducts include H₂, C₂H₄, and naphthalene (C₁₀H₈). While an MDA detailed elementary reaction mechanism is now available, a simpler global kinetic model is more useful for engineering and screening calculations. A literature three-step reaction model exists but with rate constants only at 950 K. In the current work, Arrhenius parameters for the three global reactions have been determined over 948–1023 K based on a regression of major gas species concentration data generated from Chemkin® simulations of a packed bed reactor running the detailed MDA mechanism. In addition, the three-step model is used to illustrate the need to remove H₂, perhaps through a membranous reactor wall, in order to overcome strong equilibrium CH₄ conversion limitations. Such H₂ removal, though, improves C₁₀H₈ selectivity at the expense of C₆H₆.