Electrochemical\nHydrogenation of a Liquid Organic\nHydrogen Carrier Using a Pd Membrane Reactor

Liquid organic hydrogen carriers (LOHCs) store hydrogen\nin the\nchemical bonds of organic molecules. Unsaturated molecules, like toluene,\ncan store hydrogen at densities comparable to compressed gas, but\nhave the distinct advantage of being transportable as liquids under\nambient conditions. Thermochemical hydrogenation using H<sub>2(g)</sub> requires high temperatures and pressures, whereas electrochemical\nhydrogenation can proceed at ambient conditions and without H<sub>2(g)</sub>. However, the electrochemical hydrogenation of toluene\nis limited by the low solubility of toluene (<6 mM) in water. Here,\nwe demonstrate the hydrogenation of neat liquid toluene electrochemically\nby using a palladium membrane reactor. We show that this reactor prevents\ntoluene permeation to the anode chamber, which is a persistent issue\nfor other forms of electrochemical hydrogenation. This paper outlines\nhow the membrane reactor also overcomes many other issues associated\nwith electrochemical hydrogenation, thereby enabling the hydrogenation\nof LOHCs without H<sub>2(g)</sub>.