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.

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.

Nowadays, the co-processing of middle distillates with vegetable oils is well established at an industrial scale. However, it is necessary to utilize waste oils (used cooking oils/animal fats) to obtain second-generation biofuels. The present work studies the suitability of animal fat as a feedstock for co-processing with atmospheric gas oil, paying particular attention to catalyst activity in terms of hydrotreating effectiveness and hydrotreated gas oil quality, including cold flow properties. The co-processing experiment was carried out in a fixed bed reactor for more than 260 hours, under industrial operating conditions (362–377 °C, 5.8 MPa, LHSV 1 h⁻¹, H₂ 317 Nm³ m⁻³) and an atmospheric gas oil/animal fat ratio of 90/10 wt%. The addition of animal fats did affect the hydrodesulfurisation efficiency (>99.6%). However, the co-processing affected the hydrodenitrogenation efficiency (>94.0%) more and the hydrotreated gas oil quality in the longer term. Furthermore, in the case of cold flow properties, 100 ppm seems to be the optimal value for depressant additivation to improve significantly the CFPP value (up to 10 °C). Overall, our results suggest that, while it is necessary to implement a previous cleaning step, animal fats are a suitable and promising blending feedstock candidate for co-processing with medium distillates to produce advanced biofuels.

This study aimed to determine the effect of the supplied pyrolysis oils (oils obtained from the pyrolysis of used tyres and the depolymerisation of plastics) on the activity of the hydrodesulphurisation catalyst. Each pyrolysis oil was added at 20% weight to a standard feedstock and processed on pilot plant reactors under the set conditions of a commercial unit, including an activated catalyst. Following the catalyst stabilisation, the standard material was changed to the mixture with the pyrolysis oils. The reaction conditions, particularly the reaction temperature, were controlled. The results of the product analyses were compared with the EN 590 standard for evaluating diesel fuel; the hydrogenated mixed fuel meets most requirements. Only the density, flash point, distillation curve and lubricity have minor deviations, which could be adjusted by treating the sample before or after hydrogenation. The properties of the products, in terms of the low-temperature properties, were also investigated. The tyre-derived pyrolysis oils showed improved low-temperature properties, possibly due to the higher levels of the aromatic hydrocarbons. The pyrolysis oil obtained from the depolymerisation of the plastics was found to be more suitable for use in refineries without substantially impacting the existing technologies. For the tyre-derived pyrolysis oils, higher reaction temperatures were required for processing, which could affect the catalyst operation.