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The use of depressant additives is the most effective and cost-effective way to improve the low-temperature properties of diesel fuels, like the cloud point, cold filter plugging point and pour point. However, the effectiveness of depressant additives depends on the composition of the diesel fuel and the content of certain groups of hydrocarbons in it. In this work, the effect of adding individual hydrocarbons of various groups and structures on the effectiveness of depressant additives is studied. This study is carried out on model aromatic (toluene, tetralin) and n-paraffin hydrocarbons (cetane, heptadecane, heneicosane, docosane) in various concentrations. It is shown that the most negative effect on the depressant additives’ effectiveness is due to the content of the most polar aromatic hydrocarbons and light n-paraffins in the composition of diesel fuel, and the most positive effect is exerted by the content of heavy n-paraffins in small quantities. It is proposed to involve small concentrations (1–3% vol.) of heavy n-paraffin hydrocarbons (heneicosane, docosane) to increase the effectiveness of the depressant additive. It has been established that for the more effective action of the depressant, it is necessary to take into account the content and structure of individual hydrocarbons in the diesel fuel’s composition.

Nowadays, there is a need to search for new renewable energy sources from which it is possible to obtain hydrocarbons that are similar in composition and properties to hydrocarbons of petroleum origin. This is due to a significant increase in demand for natural minerals and, as a consequence, the depletion of their reserves. Today, the most promising alternative renewable energy sources are various vegetable oils, which are used both in their pure form, adding them to commercial mineral fuels, and as products of catalytic processing using various catalysts. However, most studies in the field of alternative energy show that the use of fuels obtained from vegetable oils is limited by their properties as well as the climatic conditions of the areas where biofuels can be used. In this work, we propose an integrated approach to the processing of vegetable oils, which allows us to obtain products of a wide fractional composition with improved operational properties. This approach consists of sequential processing of vegetable oils, first using a CoMo/Al2O3 hydrotreating catalyst in order to obtain classical long-chain hydrocarbons with unsatisfactory properties, and then using a zeolite catalyst, ZSM-5 type, which is characterized by the active occurrence of cracking, isomerization, and aromatization reactions, which are accompanied by a decrease in the length of the hydrocarbon chain of the hydrocarbons obtained during the hydrotreating process and, as a result, improving the physicochemical and low-temperature properties of the resulting processed products.

Diesel fuel is the main fuel for transport and power generation for remote areas, especially the Arctic. For these territories, it is important to produce low-freezing fuel grades. The most effective way to improve the low-temperature properties of diesel fuels (cloud point, pour point, and cold filter plugging point) is the use of depressant additives. Existing research shows that the depressant additives’ effectiveness is influenced by many factors. The most important factors are diesel fuel composition, additive concentration, and the temperature of additive introduction into the fuel (adding temperature). The purpose of this work is to find ways to increase the efficiency of depressant additives for the production of low-freezing diesel fuels by choosing the most effective additive concentration and adding temperature for fuels of various compositions. During the work, low-temperature properties were determined and the effectiveness of three depressant additives was assessed on four samples of diesel fuel at four concentrations (0.5, 1.0, 2.0, and 5.0 c.u., where c.u. (conditional unit) is the concentration recommended by the manufacturer of the additives). In addition, low-temperature properties for blends of six depressant additives and two samples of diesel fuel at five adding temperatures (15, 25, 35, 45, and 55 °C) were determined. In this work, in contrast to existing works, it was established for the first time that the composition of the fuel affects not only the depressant additives effectiveness, but also the dependence of the additive effectiveness on the concentration in which it is used. It is shown that the higher the content of paraffins in the composition of the diesel fuel, the less the depressant additive’s effectiveness in relation to cold filter plugging point depends on the concentration and the more the depressant additive’s effectiveness in relation to the power point depends on the concentration. An inverse relationship was revealed for the content of aromatic hydrocarbons in diesel fuel. It was also found for the first time that an increase in the adding temperature of depressant additives up to 35–55 °C enhances the effectiveness of their action in relation to the cold filter plugging point (maximum at 6–7 °C). It is shown that the greater additive effect on the cold filter plugging point of the diesel fuel, the more strongly the depressant effectiveness depends on the adding temperature. The work provides recommendations for obtaining the most low-freezing classes of fuel based on the samples considered. The regularities identified in the work will make it possible, depending on the composition of the fuel, to select the optimal concentration of the additive and the temperature of its adding, which will increase the efficiency of the additives, as well as the volume of low-freezing grades of diesel fuel production.

The use of depressant additives is the most common method for producing diesel fuels with improved low-temperature properties. However, the depressants effectiveness largely depends on the composition of the diesel fuel, in particular on the content of n-paraffinic hydrocarbons, which to the greatest extent determine the low-temperature properties of the fuel. The work revealed the regularities of the n-paraffins addition influence on the depressant additives effectiveness. It was found that the addition of n-paraffins to blends of diesel fuels with depressants in low concentrations (0.05–0.50% wt.) enhances the depressants effectiveness in relation to the cold filter plugging point: maximum at 6–16 °C depending on the diesel fuel sample. It is shown that the effect is observed for DF of various compositions, various depressants, and also n-paraffins of various compositions. It was established that the positive effect of adding n-paraffins increases with the heavier added n-paraffins. Recommendations have been developed for obtaining diesel fuels with improved low-temperature properties and enhancing the depressant additives effectiveness: for a sample of straight-run diesel fuel F1, it is recommended to use a blend of fuel, depressant A1 and 0.50% wt. n-paraffins, separated from heavy gasoil; for a sample of straight-run diesel fuel F2, it is recommended to use a blend of fuel, depressant A2 and 0.50% wt. n-paraffins, separated from heavy gasoil or a blend of fuel, depressant A1 and 0.05% wt. n-paraffins, separated from highly paraffinic oil fraction. The revealed patterns and the developed recommendations will allow increasing the production of low-freezing DF brands, and also offer a resource-efficient option for using heavy gas oil fractions. The results obtained in the work contribute to expanding the understanding of the mechanism of interaction between diesel fuel hydrocarbons and the active ingredients of depressant additives.

The process of hydrogen-free upgrading of diesel fraction on ZSM-5 type zeolite catalyst was implemented at the laboratory catalytic unit under the conditions of varying the process temperature. The composition and characteristics of the feedstock diesel fraction and the obtained upgrading products were investigated. The obtained diesel fraction upgrading products were tested for compliance with the standards. The directions of hydrocarbon transformations in the process of upgrading on a zeolite catalyst were considered. The influence of the upgrading process temperature on the composition and characteristics of the obtained products was estimated. For the first time, the optimal technological parameters for the implementation of the upgrading process on a zeolite catalyst from the perspective of the production of arctic diesel fuel were determined.

Natural gas liquids are a by-product of natural gas preparation, one of the most common and environmentally friendly energy sources. In natural gas fields located in remote areas, there is no resource-efficient way to use natural gas liquids. However, natural gas liquids are a valuable hydrocarbon feedstock for the production of motor fuels, in particular motor gasolines. The aim of this work is to develop a method for obtaining motor gasolines by processing natural gas liquids on a zeolite catalyst, taking into account the influence of the particle size of the zeolite catalyst, the technological parameters of the process, and the composition of the feedstock. As part of the work, for the first time, regularities of the influence of zeolite catalyst particle size, technological parameters of the process and the composition of feedstock on the composition and characteristics of the resulting processed products were revealed. A database about the composition and characteristics of natural gas liquids, obtained from various gas fields in Western Siberia of the Russian Federation, has been accumulated. During the study, it was found that the optimal particle size of the zeolite catalyst is 0.50–1.00 mm; optimal technological parameters are a temperature of 375 °C, pressure 2.5 atm. and the feedstock space velocity 2 h−1. It is shown that the processing of natural gas liquids of various compositions on a zeolite catalyst, on average, makes it possible to increase their detonation resistance by more than 16 points. The results obtained indicate the prospects of using the process for the production of motor gasoline. The paper presents a number of blending recipes for obtaining fuels, both within the framework of production at the fields and at processing plants.

Experimental studies of the steam pyrolysis of oil sludge were performed using a flow-type pilot plant with 300 kg/h capacity (raw material) to obtain energy-valuable products, such as liquid hydrocarbons (30.4 wt%), semi-coke (39.6 wt%), non-condensable gas-phase compounds (26.5 wt%), and bitumen (3.5 wt%). The pyrolysis process was conducted at a temperature of 650 ° C and with a steam flow rate of 150 kg/h. Liquid hydrocarbons were considered a target product. Comprehensive studies of their physicochemical characteristics, atomization process, droplet ignition, and combustion were carried out. The studied sample had physicochemical characteristics similar to traditional fuel oil (calorific value—42.6 MJ/kg, sulfur content—0.8 wt%). The jet spraying angle was 25° in view of the improved rheological properties of the test sample, with a homogeneous jet structure and a predominant droplet diameter of no more than 0.4 mm. The flame combustion process was accompanied by the formation of microexplosions, the frequency and intensity of which depended on the temperature of the air (Tg = 450–700 °C). This study, in view of its applied nature, is of interest in the design of new installations and technological systems for hydrocarbon pyrolysis.