Kerosene from the hydrocracking is commonly used to produce JET fuel. Depending on the deactivation of the catalyst, the aromatic content of such kerosene increases to a level where it can no longer be used for JET fuel production. The objective of this study was to determine whether the aromatic content of kerosene from hydrocracking can be reduced under the conditions used for hydrotreating straight-run middle distillates. The kerosene obtained from a real hydrocracker unit was investigated in a laboratory fixed-bed unit packed with a Ni-Mo/Al₂O₃ catalyst. Aromatics content was analyzed utilizing ASTM D6379 (HPLC). As a result of the hydrogenation, the aromatic content was reduced from 22.6 to 14.5 wt.% (3 MPa) and 3.0 wt.% (6 MPa). The product contained 60–70 wt.% cycloalkanes. The smoke point was improved by 3.3 mm (3 MPa) up to 9.7 mm (6 MPa), and the cetane index by 1.1 or 3.9 units, respectively. The (H/C)_at ratio in kerosene increased from 1.89 to 1.98. Furthermore, no significant cracking occurred during the hydrogenation. Overall, we demonstrate that the aromatic content of such kerosene can be very well controlled by downstream hydrogenation under conditions common in oil refineries for the desulfurization of middle distillates.

Determination of olefins in pyrolysis oils from waste plastics and tires is crucial for optimizing the pyrolysis process and especially for the further advanced valorization of these oils in terms of the circular economy. Identifying olefins, even using high-resolution techniques like GC×GC, is challenging without TOF-MS, which allows modification of the ionization step. Currently, the only method for determining olefins in plastic pyrolysis oils is GC-VUV, recently standardized as ASTM D8519. However, TOF-MS and VUV are not affordable instruments for many research teams working on plastics recycling. This paper introduces a simple method for the selective micro-scale adsorption of olefins over AgNO₃/SiO₂, followed by the GC×GC-FID analysis. Olefins are determined indirectly from the loss of chromatographic area in respective hydrocarbon groups before and after removal. Only 50 μL sample and 15 min of sample separation are needed. Our method was extensively validated and provides a reliable determination of olefin content in a wide range of pyrolysis oils from plastics and tires and their products after mild hydrotreatment. It is affordable to all researchers and industrial companies working on plastics recycling by thermochemical processes as it does not require an MS detector.

This study compares the hydrotreating of the mixture of petroleum middle distillates and the same mixture containing 20 wt % of rapeseed oil. We also study the effect of the temperature and the weight hourly space velocity (WHSV) on the co-hydrotreating of gas oil and rapeseed oil mixture. The hydrotreating is performed over a commercial hydrotreating Ni-Mo/Al₂O₃ catalyst at temperatures of ca. 320, 330, 340, and 350 °C with a WHSV of 0.5, 1.0, 1.5, and 2.0 h⁻¹ under a pressure of 4 MPa and at a constant hydrogen flow of 28 dm³·h⁻¹. The total conversion of the rapeseed oil is achieved under all the tested reaction conditions. The content of the aromatic hydrocarbons in the products reached a minimum at the lowest reaction temperature and WHSV. The content of sulphur in the products did not exceed 10 mg∙kg⁻¹ at the reaction temperature of 350 °C and a WHSV of 1.0 h⁻¹ and WHSV of 0.5 h⁻¹ regardless of the reaction temperature. Our results show that in the hydrotreating of the feedstock containing rapeseed oil, a large amount of hydrogen is consumed for the dearomatisation of the fossil part and the saturation of the double bonds in the rapeseed oil and its hydrodeoxygenation.