Phenolic Compound Production by Kraft Lignin Pyrolysis: Effect of Temperature and Pumice as a Natural Catalyst

Abstract

The valorization of lignin derived from the pulp and paper industry has attracted significant interest due to its high aromatic content and its potential as a renewable feedstock for value-added chemicals. In this study, the production of phenolic compounds from Kraft lignin through pyrolysis at different temperatures was investigated. Experiments were conducted in a Parr Series 4740 reactor at 450, 500, and 550 °C, both in the absence and presence of pumice as a natural catalyst. The vapors generated during the process were condensed to obtain bio-oil, while biochar was recovered as the solid residual fraction. The resulting bio-oil was subjected to liquid–liquid extraction to isolate the aromatic fraction enriched in phenolic compounds. The results showed that both temperature and catalyst presence significantly influenced product distribution. In particular, the addition of pumice increased the bio-oil yield from 6.88 % to 24.28 % at 550 °C, indicating a strong catalytic effect on the conversion of lignin-derived intermediates into condensable aromatic compounds. GC–MS analysis revealed the presence of phenols, methylphenols and methoxyphenols, which are consistent with the thermal depolymerization of guaiacyl units in Kraft lignin. These findings demonstrate the potential of catalytic pyrolysis of Kraft lignin using pumice as a natural catalyst for the production of phenolic compounds.