Kinetics of the HDO of methyl-substituted phenols

The kinetics of the hydrodeoxygenation (HDO) of a series of mono- and dimethyl substituted phenols were determined in a batch autoclave reactor using a sulfided commercial CoMo catalyst. Under the reaction conditions employed (5 MPa, 300°C), the reaction proceeded by two independent parallel paths, one leading to an aromatic product and the other to a naphthenic product. Kinetic analysis showed both paths to be inhibited by reactant. The addition of ammonia suppressed both paths about equally, while H2S depressed the aromatic path appreciably more. Steric hindrance was observed when a methyl group was adjacent to the OH group. It is proposed that different active sites are responsible for the two reaction paths, one for CO bond cleavage and another for hydrogenation.