Catalytic hydrogen combustion as heat source for the dehydrogenation of liquid organic hydrogen carriers using a novel compact autothermal reactor

The experimental performance of an autothermal hydrogen release unit comprising a perhydro benzyltoluene (H12-BT) dehydrogenation chamber and a catalytic hydrogen combustion (CHC) chamber in thermal contact is discussed. In detail, the applied set-up comprised a multi-tubular CHC heating based on seven parallel tubes with the reactor shell containing a commercial dehydrogenation catalyst. In this way, the CHC heated the endothermal LOHC dehydrogenation using a part of the hydrogen generated in the dehydrogenation. The proposed heating concept for autothermal LOHC dehydrogenation offers several advantages over state-of-the-art heating concepts, including minimized space consumption, high efficiency, and zero NO_x emissions. During performance tests the process reached a minimum hydrogen combustion fraction of 37 %, while the minimum heat requirement for the dehydrogenation reaction for industrial scale plants is 33 %. The reactor orientation (vertical vs horizontal) and the flow configuration (counter-current vs. co-current) showed very little influence on the performance demonstrating the robustness of the proposed reactor design.