Asphaltene genesis influence on the low-sulfur residual marine fuel sedimentation stability

Abstract

• Genesis and structure of asphaltenes affect the stability of residual marine fuel. • Thermodestructive asphaltenes reduce the stability of residual marine fuel rapidly. • There is a residual marine fuel stability rank (TSA) from the asphaltenes genesis. This paper describes the results of studies carried out to determine the influence of asphaltene genesis on the low-sulfur residual marine fuel sedimentation stability, based on RMG 380 commercial fuel as an example. The composition and structural features of potentially acceptable residual components of marine fuels asphaltenes (vacuum residues, asphalt, visbreaker residues, heavy pyrolysis resins) and crude oil (for comparison) asphaltenes – 9 types in total – were comprehensively characterized by FT-IR, XRD, SEM, XRF, CNH analyses. The gross formulas of the examined asphaltenes were established by determining the molecular weight and elemental composition. The dependence of asphaltene genesis influence on stability was assessed by adding them in an amount of 1 to 5 wt% into RMG 380 marine fuel base compositions of constant composition according to “total sediment aged” (TSA) index. It was determined that when the asphaltene content of the studied stock types increases above 4 %, the stability of the fuel compositions, and consequently the asphaltene solubility, in the base hydrocarbon system (based on RMG 380 as an example) decreases in the following series: Asphalt → Vacuum residue → Crude oil → Visbreaker residue → Heavy pyrolysis resin.