Kinetic study of the HDN of quinoline over NiMo(P)/Al2O3 catalysts

Abstract

The kinetics of the hydrodenitrogenation (HDN) of quinoline was studied over NiMo(P)/Al2O3 catalysts at 623 K, 3.0 MPa and PH2S=6.5 kPa. Langmuir-Hinshelwood rate equations were used to model the experimental results, which involved variations in space time as well as in initial reactant partial pressure. The HDN of quinoline, 5,6,7,8- tetrahydroquinoline and decahydroquinoline were compared. The results show that the reactions of decahydroquinoline to 2-propylcyclohexylamine and of 1,2,3,4-tetrahydroquinoline to 2-propylaniline to hydrocarbons are the slowest steps in the HDN network of quinoline. Three different kinds of catalytic sites responsible for those elementary HDN steps were distinguished. The adsorption constants of quinoline-type compounds on the catalytic site for the hydrogenation of a phenyl ring are 10≈20 times larger than that of 2-propylaniline, which quantitatively explains the low reactivity of 2-propylaniline in the HDN of quinoline.