Kinetics of mesophase formation in a stirred tank reactor and properties of the products

Abstract

The kinetics of mesophase formation from a petroleum pitch and a coal tar pitch were studied in argon and hydrogen atmospheres of 1 MPa pressure at temperatures between 390 and 460°C using a stirred tank reactor. The kinetics of mesophase formation could be described by a first-order rate equation. The petroleum pitch was found to be more reactive than the coal tar pitch. The coke yield and the density of the pyrolysis residues are proportional to the tetrahydrofuran insoluble content (THF-IS) of the residues (i.e., they are independent of the pyrolysis condition under which the THF-IS was formed). The glass transition temperatures and the widths of the glass transition interval increase exponentially with increasing THF-IS content, with the exception of some products deviating from the general exponential relationship. Viscosity measurements yielded higher apparent viscosities for the products produced in hydrogen and minimum apparent activation energies for flow at THF-IS contents near 55%.