Pyrolysis Products Distribution of Enzymatic Hydrolysis Lignin with/without Steam Explosion Treatment by Py-GC/MS

Abstract

This paper investigated the pyrolytic behaviors of enzymatic hydrolysis lignin (EHL) and EHL treated with steam explosion (EHL-SE) by pyrolysis-gas chromatography/mass spectrometer (Py-GC/MS). It was shown that the main component of the pyrolysis products was phenolic compounds, including G-type, H-type, S-type, and C-type phenols. With different treatment methods, the proportion of units in phenolic products had changed significantly. Meanwhile, proximate, elemental, and FTIR analysis of both lignin substrates were also carried out for a further understanding of the lignin structure and composition with or without steam explosion treatment. FTIR result showed that, after steam explosion treatment, the fundamental structural framework of the lignin substrate was almost unchangeable, but the content of lignin constituent units, e.g., hydroxyl group and alkyl group, evidently changed. It was noticeable that 2-methoxy-4-vinylphenol with 11% relative content was the most predominant pyrolytic product for lignin after steam explosion treatment. Combined with the above analysis, the structural change and pyrolysis product distribution of EHL with or without steam explosion treatment could be better understood, providing more support for the multi-functional utilization of lignin.