GAS-PHASE PYROLYSIS OF COAL-RELATED AROMATIC-COMPOUNDS IN A COILED TUBE FLOW REACTOR .1. BENZENE AND DERIVATIVES

The decomposition of a series of aromatic hydrocarbons has been studied in a flow reactor to obtain a data set of thermal stabilities of coal-related compounds. The behaviour of alkylated benzenes generally can be predicted by the dissociation energies of the weakest bond. The presence of alkene or alkyne entities in the products or in the initial compound causes a decrease in apparent activation energies. The stability of a series of derivatives of benzene with other functional groups decreases in the sequence methoxy, thio, carbaldehyde, phenoxy, hydroxy, phenyl and cyano; in general these cannot be related directly to weakest bonds. The introduction of more substituents in the phenyl ring generally decreases stability. The kinetic data obtained predict which organic compounds are to be expected in emissions from coal pyrolysis and imperfect combustion in relation to practical reaction conditions.