Decarbonization of Chemical Manufacturing Using a Membrane Reactor

Membrane reactors use electricity and water to drive hydrogenation reactions without H₂ gas. In these reactors, a palladium membrane physically separates the site of electrochemical hydrogen formation from the site of chemical hydrogenation. This separation broadens the scope of reaction conditions (e.g., solvents) that can be studied and simplifies reagent handling and purification compared to existing electrochemical hydrogenation methods. We leveraged this feature of the membrane reactor to demonstrate the industrially-relevant hydrogenation of furfural (an important biomass derivative) into furfuryl alcohol (84% selectivity) and tetrahydrofurfuryl alcohol (98% selectivity). To achieve these selectivities, we designed and built a novel membrane reactor design that enabled high-throughput testing of combinations of solvents, catalysts (identities and thicknesses), and applied currents. One key finding was that employing bulky solvents with weak nucleophilicity suppressed side product formation to enable these high selectivities. These solvents are not compatible with conventional electrochemical hydrogenation, but they are compatible with the membrane reactor. This work highlights the utility of the membrane reactor for selective furfural hydrogenation without H2 gas, and presents the opportunity to decarbonize a >350,000 ton/year hydrogenation industry.