Abstract: Using silica gel to remove nitrogen compounds in FCC naphtha, four feeds having various nitrogen contents and the same hydrocarbon compositions and sulfur content were obtained. During the selective HDS treatment of these four FCC naphtha feeds, the effect of nitrogen compounds on the hydrogenation of olefin saturation (HYDO) was studied in a fixed-bed pilot plant over a commercial CoMo/Al2O3 catalyst, under the conditions of a reaction temperature of 285 ℃, a hydrogen partial pressure of 1.6 MPa, a LHSV of 4.0h-1 and a H2/oil volume ratio of 400. Results showed that during the selective HDS process, nitrogen compounds could inhibit the HYDO reactions, and the inhibition on linear olefins and cyclic olefins was more significant than that on branched olefins. With the same olefin saturation rate, the RON loss of product from feed having higher nitrogen content was less than that from feed having lower nitrogen content.

Key words: olefin, octane number, gasoline stock, nitrogen, hydrogenation reaction