Changes of Composition and Molecular Structures of Atmospheric Residues during Hydrotreating

Better understanding changes in composition and molecular structures of atmospheric residue (AR) duringhydrotreating is important for improving the hydrotreating performance of AR. The hydrotreating of an AR was carried out in a series of fixed bed reactors loaded with HDM and HDS catalysts, respectively. The AR and its products were fractionated into saturates, aromatics, resins and asphaltenes (SARA) and analyzed by using the gel permeation chromatography with an ultraviolet detector (GPC-UV) and with an inductively coupled plasma mass spectrometer (GPC-ICP-MS), X-ray diffraction(XRD), 13C nuclear magnetic resonance (NMR) and electron spin resonance (ESR). The hydrotreating not only decreased the contents of S, N, V, Ni, resins and asphaltenes, but also changed the composition, structure and distribution of the remained resins and asphaltenes as well as the remained S, N, V and Ni compounds in AR products. Almost all metals (V and Ni) existed in both the resins (47%) and asphaltenes (53%) fractions of A...