Post the enforcement of the Global Sulphur Cap 2020, large amounts of marine fuel have been produced as a mixture of two or more components to achieve a sulfur level of less than 0.5 wt %. This has led to the wider use of diluents or cutter stocks from different origins to comply with the quality requirements of the ISO 8217 standard. These can often be bio- or alternative components with a lower level of stability. This makes it crucial to select components that are compatible and form a homogeneous mixture. The ISO 8217 standard provides commercial and operational protection; however, the stability of the fuel deteriorates over time. Therefore, the purpose of this study was to develop an adequate component or additive to improve the colloidal stability of marine fuels. A set of laboratory-prepared samples was used to verify the positive effects of the addition of a light cycle oil and also a newly developed additive (containing 30 wt % naphthalene as the simple diaromatic hydrocarbon in tetralin). The prepared fuels (with effective additive dosage), when stored for 60 days, maintained the total sediment accelerated (TSA) parameters, confirming the stability of the fuels. The additive converted the unsaleable fuel into fuel that complied with the requirements of ISO 8217. The developed additive can be used for industrial applications in marine fuel production.

This paper focuses on the evaluation of the fuel properties of Fischer–Tropsch diesel blends with conventional diesel. Incorporating this advanced fuel into conventional diesel production will enable the use of waste materials and non-food materials as resources, while contributing to a reduction in dependence on crude oil. To evaluate the suitability of using Fischer–Tropsch diesel, cetane number, cetane index, CFPP, density, flash point, heat of combustion, lubricity, viscosity, distillation curve, and fuel composition ratios using multidimensional GC × GC-TOFMS for different blends were measured. It was found that the fuel properties of the blended fuel are comparable to conventional diesel and even outperform conventional fuel in some parameters. All measurements were performed according to current standards, thus ensuring the repeatability of measurements for other research groups or the private sector.

The stability of marine fuels is traditionally a very hot topic, especially in the beginning of so-called sulphur cap. The sulphur cap is the process of reducing the maximum level of sulphur content (from 3.5 to 0.5 wt%) in marine fuels, which are being used on deep sea from the first of January 2020. After this change, the large amount of marine fuels will be produced as a mixture of two or more components to achieve required sulphur level. Higher amounts of cutter stocks will increase the likelihood of decreased stability or compatibility of the marine fuels. Therefore, a reliable stability tests or their combination will be very important for marine fuels evaluation. However, only total sediment after aging is defined as a standard method according to ISO 8217 for stability testing. This method is not suitable for all the analysed marine fuels, so we verified using of microscopy for this type of evaluation. The set of marine fuels samples was tested using microscopy, results were processed and correlated with other selected qualitative parameters. The microscopy was evaluated as a suitable method for testing of marine fuels stability. This method could be used for very fast evaluation in industrial as well as research laboratories in combination with standard methods.

Petroleum heavy vacuum gas oil (HVGO) containing 10 wt.% of petroleum wax was hydrocracked at 390–430 °C and under the pressure of 18 MPa over a Ni W/amorphous silica-alumina catalyst in a continuous-flow fixed-bed reactor. The hydrocracking of a reference feed (neat HVGO) was carried out under the same reaction conditions. The physico-chemical properties of primary products obtained via laboratory atmospheric-vacuum distillation (heavy naphtha, middle distillates and distillation residue) were evaluated. Most products prepared from the mixed feedstock had a similar or lower density and sulfur content than the products obtained from the hydrocracking of the neat HVGO. The heavy naphtha fractions obtained from mixed feedstock contained slightly more n-alkanes and iso-alkanes and less naphthenes and aromatics. Similarly, middle distillates obtained from the mixed feedstock contained slightly more n-alkanes and less aromatics and had cetane index higher by up to 2 units.

Maritime transport is a significant contributor to the environmental pollution. For this reason, the maximum sulfur content in liquid marine fuels has been drastically reduced since January 1st 2020 for deep sea areas. This reduction can be solved by diluting the conventional high sulfur fuels with suitable low sulfur components. However, mixing two or more components with each other carries a potential risk of incompatibility or instability of the final product, especially in the case of longer storage and subsequent transportation to the end consumers. For the above reasons, this work deals with the mapping of alternative raw materials that could be used to produce very low sulfur fuel oils (VLSFO) with a sulfur level up to 0.5 wt%. A total of 5 raw materials (1 conventional fuel oil – HSFO and 4 alternative raw materials) were characterized. The individual raw materials were compared to each other with regard to the quality properties required for marine fuels according to the ISO 8217. Subsequently, the suitability of these raw materials for further mixing was outlined in order to meet the required quality parameters for marine fuel mixing.