Identification and reactivity of nitrogen molecular species in gas oils

Nitrogen molecular species in several gas oils were analyzed by gas chromatograph with an atomic emission detector (GC-AED) and mass spectrometer (GC-MS). Nitrogen species in gas oils were divided through acidic extraction into basic species (such as aniline, quinoline, benzoquinoline, and their derivatives) and nonbasic species (such as indole, carbazole, and their derivatives). To be mostly identified, their distribution depended on the cutting point and origins of gas oils. Denitrogenation reactivities of nitrogen species in gas oils were followed in the hydrotreating reactions at 340 degrees C under 5MPa of H-2 to quantify by GC-AED their respective reactivities in GOs, The reactivities orders and reactivity dependence on their chemical structures and matrix compositions are discussed on molecular bases. The reactivity order was found as indole > methylated aniline > methylated indole > quinoline > benzoquinoline > methylated benzoquinoline > carbazole > methylated carbazoles. The number and position of methyl groups were very influential on the reactivities of carbazole derivatives. Methyl groups neighboring the N atom inhibited remarkably the HDN reactions. Comparison of the reactivities of the same species in the GOs must be discussed by taking account of all components and products in the respective oil.