Glass bead-catalyzed depolymerization of poplar wood lignin into low-molecular-weight products

In this study, a kind of non-precious glass bead catalyst was prepared by a subcritical water treatment method for the depolymerization of poplar lignin. The subcritical water treatment time significantly affected the surface morphology, surface area, and active metal content of glass bead catalysts. Flaky and fibrous morphologies were found on the glass bead surface after it was treated for 60 min and 120 min, respectively. Based on the GC-MS results of monomeric products, the glass beads treated for 60 min had higher catalytic activity as compared to those treated for 120 min. The characterization results of lignin residues suggest that the glass beads are effective to prevent the repolymerization of lignin. Furthermore, the glass bead catalysts can be recycled to catalyze the depolymerization of lignin, and the yield of the monomeric products remains above 12 wt%.