Benzyltoluene/perhydro benzyltoluene – pushing the performance limits of pure hydrocarbon liquid organic hydrogen carrier (LOHC) systems?

Sustainable Energy & Fuels Pub Date: 2022-02-10 DOI: 10.1039/D1SE01767E

Abstract

LOHC technologies enable safe and efficient hydrogen logistics using the existent fuel infrastructure. This study presents benzyltoluene (H0-BT)/perhydro benzyltoluene (H12-BT) as a highly attractive technical LOHC system. Compared with the well-established LOHC systems toluene/methylcyclohexane and dibenzyltoluene (H0-DBT)/perhydro dibenzyltoluene (H18-DBT), the H0-BT/H12-B system combines high volumetric storage density and excellent robustness in hydrogenation/dehydrogenation cycles with low viscosity for easy handling under colder operation conditions. Herein, we report repeated hydrogenation and dehydrogenation cycles in semi-continuous operation at 290 °C with a commercial Pt on alumina catalyst and technical quality LOHC material. Reaction rates for both hydrogen uptake and release are generally found higher compared to those of the DBT-based LOHC system under identical reaction conditions. Side-product formation is very low during cycling the H0-BT/H12-BT system and can be traced back to a very low activity towards deep dehydrogenation forming the cyclisation product methylfluorene in four different regioisomers. Furthermore, we present the experimentally determined hydrogenation/dehydrogenation equilibrium of H0-BT/H12-BT in the temperature range between 220 and 360 °C and for total pressures of 1 and 9 barabs.

Graphical abstract: Benzyltoluene/perhydro benzyltoluene – pushing the performance limits of pure hydrocarbon liquid organic hydrogen carrier (LOHC) systems
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