Modelling and kinetics of the toluene/methylcyclohexane-based hydrogen storage system

Abstract

The coupling of toluene and methylcyclohexane is one of the most promising liquid organic hydrogen carriers. In this study, the kinetics models of toluene hydrogenation and methylcyclohexane dehydrogenation are established. The reactions were carried out in fixed bed reactors, and the kinetics parameters were fitted with the obtained data. In this experiment, hydrogenation and dehydrogenation reactions were carried out under ambient pressure. Ni/SGA_C_nTES catalyst was employed for toluene hydrogenation, the fitting activation energy $E_a$ is 36.27 kJ/mol, and the preexponential factor $k_0$ is 1212 s⁻¹. Meanwhile, the catalyst of Pt/MgAl₂O₄ was for methylcyclohexane dehydrogenation, the fitting activation energy $E_a$ is 83.92 kJ/mol, and the preexponential factor $k_0$ is 7.28 × 10⁶ s⁻¹. Aspen Plus was used to simulate on a larger scale and determine the optimal process conditions: the optimum reaction conditions for toluene hydrogenation were determined to be 185°C and 0.3 MPa, and the optimized hydrogen flow rate is 3970 kg/d (The molar ratio is 5.88). Additionally, the optimal conditions for methylcyclohexane dehydrogenation are 325°C and 0.15 MPa.