Rates, Products, and Mechanism in the Gas-Phase Hydrogenolysis of Phenol between 922 and 1175 K

Article abstract of DOI:10.1021/j100346a040

The termolysis of 0.6-6 volpercent phenol in H2 at atmospheric pressure has been examined between 922 and 1175 K.Two major initial overall reactions were observed, yielding benzene and CO, respectively: C6H5OH + H2 -> C6H6 + H2O (3) and C6H5OH -> C5H6 + CO (4).Secondary products include methane, acetylene, ethylene, ethane, naphthalene, indene, and smal amount of other hydrocarbons; these products appear to steam mainly from the C₅ species(s) formed in the course of reaction 4.Dibenzofuran was the only observed oxygen-containing product, and for a 6percent phenol feed, . + C6H5OH -> C6H6 + HO^. (22), for which log k₂₂ = (9.85 +/- O.15) - (5387 +/- 334 cal.mol^-1)/2.3RT was derived based on an equilibrium concentration of H^..Reaction 4 proceeds via phenoxy radicals, formed by H^. + C6H5OH -> C6H5O^. + H2 (30), and decomposing via C6H5O^. -> CO + C5H5^. (29).No evidence for the previously suggested direct molecular route from phenol to CO and cyclopentadiene (CP) was found; our results show that this route could account for f⁰₂₉₈(C6H5O^.)_g ca. 9 kcal.mol^-1 is derived.