The Critical Analysis of Catalytic Steam Explosion Pretreatment of Corn Stalk, Lignin Degradation, Recovery, and Characteristic Variations

Abstract

The lignin degradation and its structural change as a result of catalytic steam explosion pretreatment can be considered of great importance for both the subsequent fermentation and the further utilization of the lignin fraction. This work investigated the degradation mechanism and change in the characteristics of lignin during dilute sulphuric-acid catalytic steam explosion (SE) pretreatment and ammonia catalytic steam explosion (AE) pretreatment of corn stalk. For this purpose, two types of lignin samples obtained from the two pretreatments of aqueous products and solid residues were fractionated, and they were then characterized by a series of comprehensive analyses that consisted of gas chromatography-mass spectroscopy (GC-MS), ion chromatography (IC), Fourier transform infrared (FT-IR), Carbon-13 nuclear magnetic resonance (13C NMR), Carbon-Hydrogen two-dimensional heteronuclear single quantum coherence (13C-1H 2D HSQC), pyrolysis-GC-MS (Py-GC-MS), and field emission scanning electron microscopy (FE-SEM). Overall, the characteristic diversity of the lignin provides useful reference for high-value applications of lignin.

Keywords

• Corn stalk; Lignin; Pretreatment; Degradation; 2D HSQC