Gasification of α-O-4 linkage lignin dimer in supercritical water into hydrogen and carbon monoxide: Reactive molecular dynamic simulation study

Gasification of lignin in supercritical water is an efficient and clean way to convert biomass to high value-added fuel. The gasification mechanism of alpha-O-4 linkage lignin dimer in supercritical water is investigated by using ReaxFF reactive molecular dynamic simulation in this study. The gasification process of alpha-O-4 linkage lignin dimer, the effects of temperature and alpha-O-4 linkage lignin dimer/H2O ratio on the gasification of alpha-O-4 linkage lignin dimer are investigated. The results indicated that the major products of alpha-O-4 linkage lignin dimer are H2 and CO, and the yield of former is higher than that of latter. The first stage of the gasification process of alpha-O-4 chain lignin dimers under supercritical water conditions is the pyrolysis of alpha-O-4 chain lignin dimers, in which the alpha-O-4 bonds are broken to generate corresponding C5-C10 products. The conversion of C5-C10 and other C1 -C4 products to H-2 and CO is promoted by the H2O molecules. This work could provide an environmentally friendly, efficient and viable way for the conversion of lignin into high value-added fuel and relieve the stress of energy shortages and environmental pollution.