Boosting power density of hydrogen release from LOHC systems by an inverted fixed-bed reactor design

Hydrogen storage and transportation in form of charged Liquid Organic Hydrogen Carrier (LOHC) systems is attractive as these hydrocarbon-based carrier molecules can provide hydrogen using the existing infrastructure for fossil fuels. For hydrogen release on board of heavy-duty vehicles, however, the limited volumetric power density of the hydrogen release units was so far seen as a critical factor. Herein, we show that the power density achieved in perhydro benzyltoluene dehydrogenation in a classical fixed-bed dehydrogenation reactor can be doubled by applying an inverted multi-tubular reactor with upstream LOHC flow and hydrogen release in the reactor housing and crossflow heating through perpendicular heating tubes. The resulting power densities of up to 0.76kW(H2-LHV) L-reactor-outside(-1) (with respect to the total reactor housing), and 2.34kW(H2-LHV) L-reactor-inside(-1) (with respect to inner reactor volume) bring on-board hydrogen release of LOHC-bound hydrogen much closer to technical reality. This very impressive increase in power density is mainly due to the fact, that the inverted arrangement of catalyst bed and heat transfer tubes offers a much higher catalyst volume per reactor volume compared to a classical fixed-bed reactor.