Catalytic hydrotreatment of pyrolysis oil phenolic compounds over Pt/Al2O3 and Pd/C

A batch catalytic slurry reactor system was used to study the hydrodeoxygenation (HDO) of pyrolysis oil model compounds at high conversions and conditions similar to petroleum hydrotreatment reactors. The lignin fraction of pyrolysis oil was represented in this study by anisole, m-cresol and phenol, both individually and blended in pairs. Experiments were run from 250 °C to 350 °C using platinum on alumina (Pt/Al2O3) or palladium on carbon (Pd/C) in a Parr reactor at 50 bar. The Pt/Al2O3 catalysts exhibited ring saturation, demethylation and hydrodeoxygenation, with temperature-dependent pathway shifts. Tests with blended pairs yielded no secondary reactions but competitive adsorption for catalyst active sites was observed. Tests with Pd/C showed ring saturation followed by methanol abstraction. Rate constants and adsorption parameters were fitted to a Langmuir-Hinshelwood model for each catalyst and compound. Arrhenius relationships for those rate constants and surface adsorption parameters were then calculated. When used in a slurry reactor model with catalyst-specific reaction data, the product composition, hydrogen consumption, and energy requirements are well predicted for a known feed and set of reactor conditions.