Reactor stability for the hydrogenation of liquid organic hydrogen carriers

Liquid Organic Hydrogen Carriers (LOHCs) are promising alternatives for the safe storage and transportation of hydrogen. Among the available LOHCs, the toluene/methylcyclohexane pair has attracted significant attention owing to its favourable hydrogen-storage capacity, chemical stability, and compatibility with existing fuel infrastructures. However, the development of efficient catalytic systems and the understanding of reactor-scale operability remain critical challenges for their industrial deployment. In this work, an integrated experimental and numerical framework is proposed for the assessment of toluene hydrogenation processes. A Ru/CNF catalyst was synthesized and deeply characterized. The catalyst was subsequently tested in a laboratory-scale trickle-bed reactor under different operating conditions of temperature and hydrogen pressure. A Langmuir-Hinshelwood-Hougen-Watson (LHHW) kinetic model accounting for competitive adsorption phenomena and gas-liquid mass transfer effects was developed and calibrated using the experimental data. Kinetic parameters were estimated through a robust multi-start optimization strategy based on weighted residuals and a Soft-L1 objective function. The validated kinetic model was subsequently integrated into a dynamic reactor framework representative of an industrial-scale hydrogenation unit. Dynamic simulations, eigenvalue analysis, Strozzi-Zaldívar divergence assessment, and pseudo-arc-length continuation studies were performed to evaluate reactor operability and safety. The results demonstrated stable reactor operation throughout the investigated conditions, with no evidence of multiplicity, hysteresis phenomena, or thermal runaway behaviour. Furthermore, a batch-to-continuous start-up strategy was shown to significantly reduce the time required to reach the desired operating regime compared with conventional continuous start-up procedures.