Hydrogen and Chemicals from Renewable Alcohols by OrganoMetallic Electro Reformer (OMER)

The production of hydrogen by electrolysis of water is a well-established technology but it does not have a significant commercial impact due to its high energy cost. A recent strategy for reducing the energy cost of electrolytic hydrogen production involves the replacement of water oxidation at the anode of the electrolytic cell with the oxidation of a soluble substrate, like a bioalcohol, whose oxidation potential is much lower than that of water. This leads to a significant reduction of the potential required to produce hydrogen. The original idea presented here, consists in coupling the partial oxidation of renewable alcohols promoted by an organometallic complex [Rh(OTf)(trop2NH){P(4-n-butyl-Ph)3}] (trop2NH=bis(5-H dibenzo[a,d]cyclohepten-5-yl)-amine; OTf- = CF3SO3- = triflate; (see 1@C in figure 1 for a structure plot) with the cathodic hydrogen evolution reaction (2). We report an electrolytic device that achieves the simultaneous selective production of carboxylate compounds and high-purity hydrogen gas. This electrolyzer, that we call OrganoMetallic ElectroReformer (OMER), in contrast to electrolysis technologies based on nanoparticles, offers potentially enormous advantages as in principle every single metal atom is catalytically active, thus allowing a vastly reduced metal loading. At the same time, this technology is capable of providing simultaneously high levels of pure hydrogen production and chemicals of industrial importance by the exploitation of bioalcohols. The absence of oxygen production in the anode compartment facilitates the production of hydrogen at elevated pressures. Consequently, we hypothesize the exploitation of bioalcohol electroreforming as an essential component of the biorefinery platform using this new class of electrolyzers based on organometallic complexes.