Effect of sulfur compounds on solid deposition on metals and Inconel 718 from thermal decomposition of n-dodecane

The effects of the different sulfur compounds usually present in jet fuels on deposit formation on metal surfaces from thermal stressing of hydrocarbons were studied. A model hydrocarbon, n-dodecane, was chosen as fuel, and model sulfur compounds (thiophene, 3-methylbenzothiophene, and benzyl-phenyl-sulfide) were added to n-dodecane before thermal stressing in a flow reactor. The addition of thiophene and 3-methylbenzothiophene significantly inhibited the carbon deposition on Fe and Ni foils probably because of the surface active site blockage by the adsorption of the sulfur species. Even benzylphenylsulfide (BPS) addition inhibited carbon deposition from n-dodecane on Fe and Ni surfaces. BPS addition promoted carbon deposition on Inconel 718, which did not collect much deposit from neat dodecane stressing, or stressing with the thiophenic sulfur species. The formation of Fe and Ni sulfides on the surface of Inconel 718 could disrupt the surface stability of the alloy established by the presence of minor components.