Ternary Alloys Enable Efficient Production of Methoxylated Chemicals via Selective Electrocatalytic Hydrogenation of Lignin Monomers

Abstract

We explore the selective electrocatalytic hydrogenation of lignin monomers to methoxylated chemicals, of particular interest, when powered by renewable electricity. Prior studies, while advancing the field rapidly, have so far lacked the needed selectivity: when hydrogenating lignin-derived methoxylated monomers to methoxylated cyclohexanes, the desired methoxy group (−OCH 3 ) has also been reduced. The ternary PtRhAu electrocatalysts developed herein selectively hydrogenate lignin monomers to methoxylated cyclohexanesmolecules with uses in pharmaceutics. Using X-ray absorption spectroscopy and in situ Raman spectroscopy, we find that Rh and Au modulate the electronic structure of Pt and that this modulating steers intermediate energetics on the electrocatalyst surface to facilitate the hydrogenation of lignin monomers and suppress C−OCH 3 bond cleavage. As a result, PtRhAu electrocatalysts achieve a record 58% faradaic efficiency (FE) toward 2-methoxycyclohexanol from the lignin monomer guaiacol at 200 mA cm −2 , representing a 1.9× advance in FE and a 4× increase in partial current density compared to the highest productivity prior reports. We demonstrate an integrated lignin biorefinery where wood-derived lignin monomers are selectively hydrogenated and funneled to methoxylated 2-methoxy-4-propylcyclohexanol using PtRhAu electrocatalysts. This work offers an opportunity for the sustainable electrocatalytic synthesis of methoxylated pharmaceuticals from renewable biomass.

In situ reconfiguration of plasma-engineered copper electrodes towards efficient electrocatalytic hydrogenation

“…This deduction allows for the correlation of ECH kinetics with binding energies, consistent with the recent identification of lignin electrochemical reduction. 39…”

Efficient electrocatalytic hydrogenation of cinnamaldehyde to value-added chemicals

“…Guaiacol was selected as a suitable internal standard for this quantitative analysis. The activity of the reaction was evaluated using the following indicators: 28,31,32 Faradaic efficiency (FE) of products:…”

“…4. Since FE and current density are the main factors determining the plant-gate levelized cost of target products, 32 we calculated the boundary conditions of profit and found that the lowest economically practicable FE for our developed reaction system is 29.5% at a current density of 50 mA cm −2 , at which the corresponding plant-gate levelized cost of COL equals its market price of 8955.20 $ per ton. Actually, this work has achieved an FE of 41.15% for COL at a current density of 50 mA cm −2 and the corresponding TEA result revealed that the plant-gate levelized cost of ECH technology for COL is about 5532.37 $ per ton, far lower than its market price.…”

Advances in Catalytic Depolymerization of Lignin

“…As a result, PtRhAu electrocatalysts achieve a record 58 % faradaic efficiency toward 2-methoxycyclohexanol from the lignin monomer guaiacol at 200 mA/cm 2 . [132]…”

“…It was found that Rh and Au modulate the electronic structure of Pt and this modulating steers intermediate energetics on the electrocatalyst surface to facilitate the hydrogenation of lignin monomers and suppress C‐OCH 3 bond cleavage. As a result, PtRhAu electrocatalysts achieve a record 58 % faradaic efficiency toward 2‐methoxycyclohexanol from the lignin monomer guaiacol at 200 mA/cm 2 [132] …”