PNNL

Abstract

Mechanochemical reactions are performed to depolymerize organosolv lignin with sodium hydroxide in a mixer ball mill. GPC analysis reveals rapid depolymerization into small oligomers occurs within minutes of milling time, followed by a slower reduction in average molecular weight over the next 8 hours of milling. Additionally, monomeric products are identified and quantified by GC-MS. Depolymerization appears to be limited by the occurrence of condensation reactions. Suppression of these condensation reactions can be achieved through the addition of methanol as a scavenger or adjustment of the moisture content of the feedstock. These modifications result in lower average molecular weights and higher monomeric yields. These results are an important step towards designing an efficient pathway for lignin valorization.