Kinetics of mesophase formation in a stirred tank reactor and properties of the products—VI. Catalysis by iron benzoate and naphthoate

Abstract

Iron benzoate and naphthoate were studied as catalyst precursors of an iron-catalyzed pyrolysis of a coal-tar pitch as a technical hydrocarbon mixture and of anthracene as an aromatic model compound. The results are compared with those obtained with ferrocene, which has been studied previously. Both iron compounds are decomposed by formation of iron clusters at a much lower temperature than ferrocene. For this reason the catalytic effect of iron is found at shorter reaction times and particularly at lower temperatures. Anthracene is converted to a semi-coke at temperatures as low as 444 °C. In pitch pyrolysis, the catalytic activity of iron is limited, because the iron is poisoned by formation of iron sulfides. With iron benzoate, but not with iron naphthoate, the nucleation and growth of mesophase spheres is strongly influenced. Spherulites are nearly equal in size and have a reduced tendency to coalesce up to very high spherulite content. The surface of the spheres is disturbed by segregated material containing iron sulfide. Similar results were also found with ferrocene.