Electrochemical hydrogenation of the hydrophobic oily phase of pinewood and wheat-straw pyrolysis oils in methanol

Abstract

Efficient electrochemical hydrogenation (ECH) of organic compounds is essential for sustainability, promoting chemical feedstock circularity and synthetic fuel production. Yet in bio-oil, phase separation in aqueous media restricts ECH to the aqueous fraction and leaves the hydrophobic oily phase comparatively inaccessible. Herein, we test whether methanol catholytes can directly engage the hydrophobic oily phase of pinewood and wheat-straw pyrolysis oils in an H-type cell. Using a PtRu/ACC cathode with NaCl or TBAHFP dosed by mass, we tracked composition as internal-standard-normalised GC–MS responses with qualitative FTIR support and assessed cathode condition by SEM/EDS. Phenolic responses decreased preferentially; FTIR indicated reduced aromatic character with condition-dependent O–H and aliphatic C–H envelopes, and additive choice set a trade-off with surface condition. This paper establishes chemical tractability of oily-phase ECH in methanol under mild conditions and identifies additive-dependent degradation as a dominant practical constraint.