ReaxFF-MD simulation investigation of the degradation pathway of phenol for hydrogen production by supercritical water gasification

Wastewater from the thermochemical conversion of coal and biomass contains a significant amount of phenolic structures compounds.The degradation of these phenolic compounds to hydrogen-rich gasses can prevent envi-ronmental pollution and save energy.Supercritical water(SCW)gasification of phenol is experimentally studied and a reactive force field molecular dynamics(ReaxFF-MD)simulation is conducted to investigate the catalytic mechanism of Ni/Al2 O3 in the phenol degradation.The experimental results indicate that Ni/Al2 O3 facilitates the conversion of phenol to 1-ethoxy butane via ring opening,which is a crucial step for complete gasification.The ReaxFF-MD simulation demonstrated that Ni facilitates the formation of H3 O free radicals and Ni-phenol inter-mediates.H3 O free radicals can be decomposed into H2 and OH free radicals.Both the generated OH free radical and Ni-phenol intermediate promote the ring-opening reaction of phenol.Ni promotes the direct decomposition of phenol into C1,C2,and C3 fragments,which is beneficial for further complete gasification.