(532k) Electrocatalytic Upgrading of Model Compounds Derived from Pyrolysis Oil

The production of renewable fuels has become necessary as fossil fuels continue to deplete past the point of no return.¹ Biomass pyrolysis has emerged as a promising solution for the production of liquid fuels due to its ability to convert high carbon content feeds into fuel. Pyrolysis oils, however, struggle from low yields and increased heteroatom content.² In order to solve this problem, pyrolysis oils must undergo an upgrading step to remove heteroatoms such as oxygen and nitrogen and increase the fuels hydrogen saturation. Conventionally, upgrading has occurred through thermochemical processes using high temperatures (>300 °C) and high-pressure hydrogen (10-20 MPa).³ Recently researchers have proposed electrochemical upgrading as a greener, less intensive alternative which requires milder temperatures (30-80 °C) and eliminates the hydrogen demand through in situ hydrogen generation.³ Though initial results on electrocatalytic upgrading have been promising, few researchers report appreciable yields of fully deoxygenated products and the efficiency remains low at high current densities.³

This work presents the upgrading of bio-oil model compounds in an electrochemical cell (H-Cell), wherein the anode and cathode are separated by a Nafion^® 117 membrane. Preliminary results shown in Figure 1 highlight the de-oxygenation of phenol to cyclohexanol, cyclohexanone, and cyclohexane in under 120 min. The work showcases the potential for electrochemical upgrading of pyrolysis oils, achieving greater than 50% conversion in 120 minutes at 100 mA of constant current. This work aims to further study phenol, guaiacol and vanillin as model pyrolysis oil constituents to aid in understanding the role of the electrode support, active metal, and electrolyte on oxygen removal and hydrogenation efficiency.

References

(1) Green Chem., 2016, 18, 4145

(2) Bioresource Technology 189 (2015) 30–35

(3) ChemSusChem 2021, 14, 1037–1052.