Hydrogen transfer promoted ring growth during catalytic resid hydroprocessing

Abstract

A model feedstock consisting of dibenzothiophene, dibenzofuran, quinoline, and phenanthrene dissolved in heptane has been hydroprocessed in a flow reactor at 6.89 MPa and 400 °C over a series of nickel-molybdate catalysts. Under simultaneous processing, the main product of dibenzothiophene hydrodesulphurization was diphenyl, the main product of quinoline hydrodenitrogenation was propylcyclohexane, and that of dibenzofuran hydrodeoxygenation was cyclohexyl benzene. Sulphur was removed without the need for saturation of the sulphur-containing ring. For both nitrogen and oxygen removal, the ring containing the hetero atom was saturated before scission of the CN or CO bond. The main products of the hydroprocessing of phenanthrene were hydroderivatives of varying degrees of saturation. Very little hydrocracking took place under our conditions, and this occurred predominantly by successive saturation and cracking of terminal rings. With increasing catalyst acidity, the rates of all reactions studied increased, as did the degree of hydrocracking relative to hydrogenation. Coke formation on the catalyst also increased markedly with acidity.