Transformation of Nitrogen Compounds through Hydrotreatment of Saudi Arabia Atmospheric Residue and Supercritical Fluid Extraction Subfractions

Abstract

Atmospheric residue (AR) from Saudi Arabia (SZAR) was subjected to supercritical fluid extraction fractionation (SFEF) and four extractable subfractions (SFEF-1–4) and an unextractable end-cut were obtained. SZAR and SFEF-1–4 were subjected to hydrotreatment (HDT) in a continuous mini fixed-bed reactor. Three commercial catalysts were used to remove the impurity in the feedstock. The composition and structural transformation of nitrogen (N)-containing compounds were investigated. Electrospray ionization (ESI) Fourier transform–ion cyclotron resonance mass spectrometry (FT-ICR MS) was used for molecular characterization of N-containing compounds of SZAR, extractable SFEF subfractions, and HDT products. Results showed that N1 class species with high aromaticity and/or low carbon number exhibited higher catalytic hydrogenation reactivity. N1 class species with lower aromaticity were removed regardless of chain length.