Structure and carbonization properties of pitches produced catalytically from aromatic hydrocarbons with HF BF₃

Carbonization properties of pitches synthesized from some aromatic hydrocarbons by the aid of HF BF₃ were studied under atmospheric 1.1 and 3.1 MPa pressures. The highest coke yields obtained under atmospheric pressure and 3.1 MPa were 64% and 85%, respectively, both of which were observed with anthracene pitch. Pyrene pitch exhibited a low coke yield of 37% under atmospheric pressure, but as high as 85% under 3.1 MPa. The pitches were revealed with ¹H-NMR and FD-MS to consist essentially of oligomers of starting aromatic rings such as dimers, trimers, and tetramers. The oligomers carried significant amounts of naphthenic hydrogens, which provide their low softening point and enable the development of an anisotropic flow texture when the pitch was carbonized. The carbonization scheme is discussed in relation to the coke yield.