Thermally manageable and scalable reactor configurations towards efficient hydrogen release from liquid organic hydrogen carriers

Abstract

In the global pursuit to minimize carbon emissions, hydrogen has emerged as a prominent alternative energy solution. This research introduces a thermally efficient, scalable, and potentially carbon–neutral system for releasing hydrogen, employing methylcyclohexane as a liquid organic hydrogen carrier (LOHC). Our heat supply mechanism utilizes benzyltoluene as a liquid–gas phase change material (PCM) to facilitate effective heat transfer from the heating units to the reactor. We have developed catalysts with high dispersion and Pt loading of Pt/γ-Al2O3 that maintain performance over extended periods, achieving a hydrogen extraction rate of 2.3 Nm3H2(g)/h (equivalent to 5 kgH2/day) in a bench-scale reactor. The bench-scale setup achieves near-equilibrium conversion at a space velocity of 2 LLOHC/(Lcat-h) and 310 °C. The PCM-enhanced system supports a scalable catalytic bed design and simplifies heat supply and startup through the use of various heating methods. We then compare catalytic dehydrogenation reactor setups using single and hybrid heat sources; the former includes an internal Joule heater, offering simplicity and reduced heat loss but depends heavily on electrical energy, while the latter combines the internal Joule heater with an external fuel combustor, facilitating rapid startup albeit with increased heat loss. Lastly, we suggest future research directions to address existing technological hurdles and to expand the application of this system in scaling up hydrogen release processes.