Chemical utilization of hydrogen from fluctuating energy sources – Catalytic transfer hydrogenation from charged Liquid Organic Hydrogen Carrier systems

Denise Geburtig,Patrick Preuster,Andreas Bösmann,Karsten Müller,Peter Wasserscheid

doi:10.1016/j.ijhydene.2015.10.013

Abstract

Liquid Organic Hydrogen Carrier (LOHC) systems offer a very attractive way for storing and distributing hydrogen from electrolysis using excess energies from solar or wind power plants. In this contribution, an alternative, high-value utilization of such hydrogen is proposed namely its use in steady-state chemical hydrogenation processes. We here demonstrate that the hydrogen-rich form of the LOHC system dibenzyltoluene/perhydro-dibenzyltoluene can be directly applied as sole source of hydrogen in the hydrogenation of toluene, a model reaction for large-scale technical hydrogenations. Equilibrium experiments using perhydro-dibenzyltoluene and toluene in a ratio of 1:3 (thus in a stoichiometric ratio with respect to H2) yield conversions above 60%, corresponding to an equilibrium constant significantly higher than 1 under the applied conditions (270 °C).

Highlights

As the production of electricity from wind and sun is highly intermittent in character, storage technologies are required to adapt production to demand
We focus on the transfer hydrogenation from perhydro-dibenzyltoluene to toluene
The here reported results show very interesting technical potential for the use of hydrogen-charged Liquid Organic Hydrogen Carrier (LOHC) systems as source of hydrogen in the chemical industry via a direct transfer hydrogen reaction. This utilization of hydrogencharged LOHC systems would create a direct link between hydrogen production from unsteady renewable sources via electrolysis and its high-added value use in the chemical industry in steady-state hydrogenation processes

Summary

Introduction

As the production of electricity from wind and sun is highly intermittent in character, storage technologies are required to adapt production to demand. Besides energetic use of the produced hydrogen, the latter can be used as feedstock in catalytic hydrogenation reactions This economically very interesting way of hydrogen utilization often requires transport of hydrogen from the place of renewable electricity production to a chemical production site. In this context, chemical hydrogen storage and transport systems are highly interesting. Chemical hydrogen storage and transport systems are highly interesting These should allow storing large amounts of hydrogen and release of pure hydrogen on demand. For both requirements the application of Liquid Organic Hydrogen Carrier (LOHC) systems is very attractive. LOHC systems consist of a pair of high-boiling, liquid organic molecules e a hydrogen-lean compound and a hydrogen-rich compound e that can be reversibly transformed into each other by catalytic hydrogenation and dehydrogenation reactions [4e7]

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