Chemical reactions of oily sludge catalyzed by iron oxide under supercritical water gasification condition

Supercritical water gasification is a promising technology in dealing with the degradation of hazardous waste,such as oily sludge,accompanied by the production of fuel gases.To evaluate the mechanism of Fe_(2)O_(3) catalyst and the migration pathways of heteroatoms and to investigate the systems during the process,reactive force field molecular dynamics simulations are adopted.In terms of the catalytic mechanisms of Fe_(2)O_(3),the surface lattice oxygen is consumed by small carbon fragments to produce CO and CO_(2),improving the catalytic performance of the cluster due to more unsaturated coordination Fe sites exposed.Lattice oxygen combines with*H radicals to form water molecules,improving the catalytic performance.Furthermore,the pathway of asphaltene degradation was revealed at an atomic level,as well as products.Moreover,the adsorption of hydroxyl radical on the S atom caused breakage of the two C-S bonds in turn,forming·HSO intermediate,so that the organic S element was fixed into the inorganic liquid phase.The heteroatom O was removed under the effects of supercritical water.Heavy metal particles presented in the oily sludge,such as iron in association with Fe_(2)O_(3) catalyst,helped accelerate the degradation of asphaltenes.