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

•Gasification mechanism of α-O-4 linkage lignin dimer in supercritical water is studied.•Gasification process of α-O-4 linkage lignin dimer in supercritical water is described.•Effects of temperature and α-O-4 linkage lignin dimer/H2O ratio are analyzed.•H2 and CO rich gaseous products could be selectively achieved.