Production of phenolic chemicals from hydrolysis lignin via catalytic fast pyrolysis

Abstract

Catalytic fast pyrolysis of hydrolysis lignin was investigated in a drop-tube fixed bed reactor at different temperatures ranging between 400–800 °C using zeolite X as a catalyst for the production of phenolic chemicals. The yield of low molecular weight monomeric phenolics increased considerably while increasing the pyrolysis temperature from 400 °C to 450 °C, but decreased with further increasing the pyrolysis temperature. Zeolite X remarkably increased the yield of monomeric phenolic compounds in the catalytic fast pyrolysis of hydrolysis lignin at all temperatures (400–800 °C) compared to fast pyrolysis. No significant changes were observed in the catalyst properties (crystallinity and textural structure) during fast pyrolysis of lignin. The superb activity of the zeolite X catalyst might be owing to its strong acidity and low pore volume. Under the best reaction conditions tested in this study (450 °C, with zeolite X catalyst), the bio-oil yield was 50.5% in relation to the dry lignin, and the content of monomeric phenolics (mainly guaiacol, syringol, 4-methoxy-3-(methoxymethyl) phenol and metoxyeugenol) was 146.2 mg/g of bio-oil.