Pinewood and wheat straw bio-oil aqueous phase electrochemical hydrogenation utilising a PtRu/ACC catalyst

Abstract

Bio-oil from biomass pyrolysis contains a wide range of oxygenated compounds, limiting its direct use as a fuel due to chemical instability and low energy density. This study investigates the application of electrochemical hydrogenation (ECH) as an alternative to the conventional hydrogenation process to upgrade bio-oil derived from wheat straw and pinewood. Experiments were conducted in a two-chamber electrochemical cell, with ECH conditions optimised based on prior research. Platinum–ruthenium on activated carbon cloth (PtRu/ACC) was selected as the catalyst for ECH reactions. The process preferentially reduced phenolic and carbonyl compounds while increasing the concentration of alcohols, as confirmed by gas chromatography-mass spectrometry (GC-MS) and Fourier transform infrared spectroscopy (FTIR) analyses. The ECH study revealed substantial reductions in phenolic compounds, notably p-cresol (62.1%) and phenol (29.3%), alongside an increase in alcohol content from 49.3% to 56.5% in pinewood-derived bio-oil. These chemical transformations demonstrate ECH's potential as a milder, more sustainable alternative to traditional hydrodeoxygenation processes. This study provides insights into the ECH process and suggests future directions for optimising bio-oil upgrading and supporting the development of renewable fuels.Engineering and Physical Sciences Research Council (EPSRC)The authors are grateful for the pyrolysis liquid supplied for this research from the Biochar CleanTech Accelerator project. Innovate UK Project No. 10055261. The authors also wish to thank UK EPSRC (EP/T518104/1) for supporting the work published in the paper through an EPSRC Doctoral Training Partnership Funding.Sustainable Energy & Fuel