HYDROGENATION OF POLYNUCLEAR AROMATIC-HYDROCARBONS .2. QUANTITATIVE STRUCTURE-REACTIVITY CORRELATIONS

A consistent data base of reaction pathways, kinetics, and mechanisms for catalytic hydrogenation of one-, two-, three-, and four-fused arom atic ring compounds allowed for correlation of their Langmuir-Hinshelw ood-Hougen-Watson (LHHW) rate law parameters with molecular structure. A total of 68 hydrogenation and dehydrogenation rate law parameters f or 28 aromatic and hydroaromatic compounds were summarized into 7 para meters for quantitative structure/reactivity correlations (QS/RC) that characterized the associated set of series of homologous reactions, i .e. reaction families. Evaluation of the 28 LHHW adsorption constants was accomplished by imposing a correlation betwen the adsorption const ant and the number of aromatic rings and the number of saturated carbo ns. Surface reaction rate constants correlated with the enthalpy of hy drogenation and the highest bond order in the aromatic ring being satu rated. Semiempirical molecular orbital calculations provided acceptabl e estimates of the enthalpy of reaction, which, via compensation, prov ided estimates of the entropy of reaction, and thus equilibrium consta nts. The overall parity between measured parameters and those predicte d by the 10 QS/RC parameters was very good, and allowed for 88% reduct ion in the number of parameters needed to model the saturation kinetic s of polynuclear aromatic hydrocarbons.