In terms of solutions, it is proposed to subject normal and weakly branched paraffin hydrocarbons to low temperature isomerization process [2]. In world practice, several modifications of the isomerization process are used, which differ in the catalysts used and the process conditions. The use of new modificated catalysts enable to increase the high octane components of modern gasolines, so that the involvement of saturated hydrocarbons to the process contributes to the solution of this problem.

Natural gasoline is the mixture of C₅-C₇ and C₇₊ paraffins, that have certain difficulties. For instance, the presence of C₇₊ n-paraffins can lead to the formation of undesirable gaseous products due to the hydrocracking or hydrogenolysis of branched isomeric structural hydrocarbons [3]. In order to maintain the high efficiency of isomerization process catalyst, it is necessary to limit the content of C_{7 +} paraffins in the feedstock. Furthermore, due to the importance of C₅-C₆ izomers which have high-octane number, it is important to increase the amount of normal and weakly branched paraffin hydrocarbons.

Experimental Part

The multicomponent catalysts consist of А(γ-Al₂O₃) or HMOR zeolite (SiO₂/Al₂O₃=17) and anion SO₄^2- modified sulfated zirconia (SZ). The components of the composite catalyst were prepared by modifying the initial MOR zeolite with cobalt, nickel or zirconium. The modification of the original zeolites was carried out by decationization, dealumination, ion-impregnation of various metals, impregnation with a solution of a sulfating agent (NH₄)₂SO₄, based on the number of ions.

As a active components ZrO (NO₃)₂∙ 2H₂O and (NH₄)₄W₅O₁₇ ∙ 2.5H₂O salts were used so as to prepare catalysts. For the synthesis of catalysts zirconium dioxide gel was obtained by hydrolysis of ZrOCl₂ with a solution of 25% ammonia at pH = 8-9 [3]. The deposition of the salts on the H-form of the zeolite was carried out by impregnation for 24 hours with further evaporation, drying, mixing with a binder component Al₂O₃ (25% of the catalyst mass) and subsequent heat treatment at different temperatures during 4 hours. The new prepared composite catalyst is 65 wt.% of Al₂O₃ or zeolite, 15% SZ and the rest is binder. The main features of the reaction resulting products have been done be means of «Auto System XL, Perkin Elmer» chromatography provided with the relevant computer program.

Results and Discussion

Catalytic isomerization process is one of the predominant processes in modern oil refining that is used in order to obtain high-octane isocomponents for motor fuels. The process should be carried out in such a way as to maintain a minimum yield of aromatics and olefins, which is achieved by selecting the catalyst and the process conditions.

In addition, important argument for the inclusion of an isomerization unit in the oil refining scheme is an increase in the octane stock of the entire gasoline stream, which makes it possible to reduce the “rigidity” of the reforming process. The latter leads to an increase in the yield of reformate and the concentration of aromatic hydrocarbons simultaneously decrease in commercial gasolines [4,5].

All components of the original natural gasoline over the Ni/MOR/SZ undergo considerable amount of changes. The content of the iso-C₅, n-C₅, and iso-C₆ components in the catalyst increases, while the content of the remaining components decreases. Among the changes noted, it is necessary especially to note a decrease in the concentration of hydrocarbons C₄, C₆ and ∑C_{7 +}. Changes in the distribution of hydrocarbons before and after contact with the catalyst are depend on temperature and process.

Table 1 – Conversion of natural gasoline over the Ni/MOR/S; WHSV= 2 h^-1; υ_Н2 =30 ml/min

As can be seen from the table 1, the contact of natural gasoline with the Ni/MOR/SZ catalyst allows not only isomerization of the C₅ and C₆ alkanes, but also the involvement of the heptane to the process. The conversion of this component in the temperature range of 150-200⁰C is around 40-49%, while the products of this conversion are only high-octane alkanes iso-C₅, iso-C₆ and n-C₅. It also should be noted that the C₆ components of natural gasoline are also involved in the formation of these components. In other words it is obvious that natural gasoline is significantly enriched in higher-octane components in one pass over the catalyst due to extremely declining of low-octane heptane components. The noted changes in the distribution of hydrocarbons contribute to a natural change in the octane quality of the mixture. The evaluation of the octane characteristics of the feedstock, presented in Table 1, indicates that in one pass over the catalyst, the RON of gasoline can increase by 17-23 points. Thus, compounding of reformate with the obtained fraction can become a perspective method for producing high-octane gasolines that meet modern requirements.

Conclusions

The possibility of using Н-zeolite/SO₄^2-(WO₄^2-)ZrO₂ catalytic systems for the conversion of hydrocarbon mixtures of natural gasoline at low temperatures of 140-200⁰С and the accumulation of C₅-C₆ alkanes are formed as a result of isomerization, decomposition of bimolecular intermediate and as well as the involvement of C_{7 +} alkanes to the process without the formation of undesirable gaseous alkanes can open new avenue for using such catalytic systems for isomerization processing (isoforming) of stabilized gasoline containing significant amounts of C_{7 +} alkanes.

Synthesis of mono  diethylene glycol – and diesters on the basis of C₄-C₁₀ fatty acids in the presence of salts of petroleum acids (cobalt-, zirconium- and zirconyl) (5-6% by weight of acid) and their properties were studied [1].

Ionic liquid was synthesized in the presence of 1,4-dimethylpyperazine hydrosulfate catalyst on the basis of valerian-, kapron acids and diphenylolpropane propylene oxide monoether with divalerianate, dicapronate esters components – alcohol: acid-1,05:2 ratio, at 80-90⁰C temperature for 5 hours . The difference between this catalyst and other catalysts is that the catalyst is taken in small amounts, which causes the reaction to be carried out under mild conditions, in a short time and without the formation of resin. Under these optimal conditions, the yield of the target product is 85-90%. Physico-chemical parameters of diesters were determined and their structures were identified by spectral methods. The synthesized diesters have been tested to improve the thermoxidation stability of diesel fuel and it has been determined that these diesters can be used as antioxidants in diesel fuel [2].

In the article [3], in the presence of nano-TiO₂ catalyst (1.2% by weight of acid), natural oil acid and diphenylolpropane propylene oxide monoether in a ratio of 2:1 mol at a temperature of 110-120⁰C was synthesized in 14-15 hours. Physicochemical parameters of the synthesized diaphragm were determined and identified by spectral methods. The article also shows the advantages of the catalyst in the etherification process and its testing as an antioxidant for diesel fuel.

It is known from the literature [4] that glycol esters of carbonic acids are mainly offered as plasticizers and are of great interest in this regard. It is known from the literature that petroleum acids are obtained on the basis of the reaction of alkali salts of ethylene glycol esters with dichloro ethane and that they are offered as plasticizers in the manufacture of polyvinyl chloride and rubber products. The researchers showed that alkyl esters in the presence of nano TiO₂ (P-25, PC-10) catalyst at 110-150⁰C for 3-3.5 hours in the presence of triethylene glycol, valerian, kapron, peralgon, etc. esters of carbonic acids were synthesized and tested as a plasticizer in polyvinyl chloride polymers.

In the study [5, 6] in the presence of a natural oil acid trimethylol-propane and a nano TiO₂ (PC-50) catalyst, a compound of ether was synthesized at 80⁰C with a yield of 80% for 6 hours, proposed as a plasticizer, and with dioctylphthalate industrial plasticizer. were compared. In the literature, synthetic petroleum acid was synthesized in the presence of nano TiO₂ and optimal conditions for the etherification reaction were found and the material balance of the process was established.

Ethylene glycol monoethers with aliphatic unsaturated acids have been synthesized to synthesize mixed diaphragms of ethylene glycol [7]. A KU-2-8H catalyst, a hetero catalyst, was used as the catalyst, and mixed unsaturated diaphragms based on oxyethers were synthesized, which were proposed as new monomers.

The petroleum acid taken as a raw material in the submitted research work was taken from Azerneft Oil Refinery. Naphthenic acid separated from kerosene-gasoyl fraction and benzoic acid as fatty acid were used as distilled petroleum acid. Mono and bis ethers were obtained on the basis of ethylene glycol taken as a raw material. First, the purified petroleum acid was expelled under vacuum, and then synthesis reactions were carried out on its basis. Physicochemical parameters of petroleum acid used as a raw material in the study were determined and given in Table 1.

Table 1 – Physicochemical properties of distilled petroleum acid (DNA)

Taking into account the above, the main purpose of our research was the synthesis of mono esters of natural petroleum acids and carbonic acids in the presence of ionic liquid catalysts. On the basis of synthesized mono esters, benzoic acid was used to synthesize diaphragm.

The live broadcast reaction was carried out in a three-throat flask equipped with a mechanical stirrer, a dropper funnel and a thermometer. To the flask was added 1 g/mol of petroleum acid in the amount of 10 g/mol of ethylene glycol, acid catalyst (ionic liquid N-methyl-pyrralidone hydrosulfate) in the amount of 5%, and benzene (100ml) as a solvent. The reaction was carried out at 80-90⁰ 0C for 5 hours. During the reaction, two layers are formed: the upper and the lower layer. The top layer is glycol ether of petroleum acid, and the bottom layer is the unreacted amount of ethylene glycol, which is separated from the reaction mixture by a separating funnel. After neutralizing the top layer, it was expelled in a vacuum and its physical and chemical properties were studied. Mono and bis ethers were synthesized by changing the molar content of the reactants. The etherification reaction was obtained with a yield of 80-90% for the following reaction:

Some physicochemical parameters of synthesized mono and bis ether: boiling point of mono glycol ether of petroleum acid145-240⁰C; acid number 0.5 mg KOH/g, Radiation coefficient, 1.4735; density 0.9765g/cm³.

Bis glycol ether of petroleum acid boiling point 195-295⁰C; acid number 1.0 mg KOH/g, Radiation coefficient 1.4680; density 0.9820g/cm³.

Ionic liquid N-methyl-pyrralidone hydrosulfate was used as a catalyst in the direct ether reaction. Our goal in using this catalyst was to be environmentally non-toxic, to avoid any resin during the reaction, and to obtain ether with high yield. The catalyst was obtained according to a known method in a three-necked flask equipped with a thermometer, drip funnel, mixer and water bath. Sulfuric acid is added dropwise to the system at 0⁰C for one hour. Then we carry out the reaction at room temperature for 24 hours. The resulting product is dried after washing the catalyst. The reaction takes N-methyl-pyrralidone and H₂SO₄ (98.8%) in a ratio of 1:1. The obtained catalyst was considered profitable because it can be used several times in the etherification reaction.

It has also been possible to obtain natural petroleum acid diaphragms with ethylene chloride. The experiment was carried out according to the above method, but with the participation of 40% alkali solution. The reaction was carried out according to the following scheme and was obtained with a yield of 85-90%.

In order to obtain carbon dioxide, the mono ether of carbonic acids (capron, caprylic) was carried out by the reaction with benzoic acid by the above-mentioned method: 

Here R – naphthenic, kapron (C5 H11-), enant (C6H13-) radical

Physicochemical parameters of natural petroleum acid and carbonic acid monoether are given in the table.

Table 2 – Physicochemical properties of natural petroleum acid and carbonic acid monoether

The direct esterification reaction was carried out with 1.2:1 mol of benzoic acid of the reagents involved in the reaction (naphthenic acid, caproic acid, caprylic acid), soluble in toluene medium with 5% catalyst (ionic liquid N-methylpyrrolidone hydrosulfate) for benzoic acid. The etherification reaction was carried out for 5-6 hours at a temperature of 110⁰C. The amount of water released during the reaction was 2 g. The resulting product is neutralized with 1% triethanol amine solution, the solvent is expelled, the obtained ethers are expelled in a vacuum.

Benzioate Naftenate diaper was expelled at a pressure of 250-330⁰C/0.8 kPa and physico-chemical parameters were determined:; d420 = 0.960; nd20 = 1.4780; acid number 0.7 mg KOH/g, yield 86%;

Benzoate kapronate diesel; d4²⁰ = 1,044; nd²⁰ = 1.4710; acid number 0.7 mg KOH/g, yield 85%;

Benzoate enanthate diesel; d4²⁰ = 1,031; nd²⁰ = 1.4752; acid number 0.5 mg KOH/g, yield 84.5%;

The structures of the obtained ethers were confirmed by modern analysis methods IR and NMR. It was taken on the Bruker spectrometer by ALFA IR-Fourier. In the IR spectral analysis, 710 for the benzene ring, 1110,1173 for the C-O-C bond, 1271 cm^-1, 1723 for the ether group, and the absorption band of the CH deformation and valence bond in the CH₂ and CH₃ groups were 1370-1450, 2850, 2927. In addition, in the CH₂ group close to the CO group, the absorption band of the CH bond was 1410 cm^-1, for the CO group C = O 1700 cm^-1, for the C-O 1170 and 1230 cm^-1.

Chemical slip signals for CH₂ and CH₃ groups according to NMR analysis

δ = 0.88-1.3m.h., characteristic for naphthene hydrocarbon protons 1.8-2m.h., signal for methylene protons 3.27-3.37m.h. was observed.

The synthesized diesters , including naphthenic acid monoethylene glycol benzoyl ether, were tested in PVC (polyvinyl chloride) resin as a plasticizer and compared with the standard dioctylphthalate (DOF) and confirmed to be replaceable. The direct esterification reaction was carried out in the presence of a mono, bisester ionic liquid catalyst of petroleum acid. N-methylpyrrolidone hydrosulfate was used as the catalyst for the ionic liquid. The catalyst is environmentally friendly and more cost-effective as it can be reused. Due to the short etherization time, no resin product was observed during the reaction and it was synthesized with high yield. The mono, bis ether of the synthesized petroleum acid has been proposed as a plasticizer due to its superior properties compared to the industrial catalyst.

The volume of mining in our country is increasing significantly every day. However, only 55-65% of these minerals have been used so far. The rest of the amount in the form of waste remains unused, polluting the atmosphere, hydrosphere and lithosphere [1].

The main directions for the integrated use of minerals and protection of mineral resources. It is known that the protection of mineral resources is understood as scientifically sound rational and careful use of minerals, the most complete technically accessible and economically feasible extraction of them, waste disposal.

The main measures for the protection of mineral resources are based on resource conservation:

- prevention of losses during the extraction, transportation of minerals, during their enrichment and processing, the use of finished products. Significant losses of minerals and environmental damage occur during the development of deposits by underground method.

According to the purpose of minerals, the following types are distinguished:

• Combustible minerals (oil, natural gas, oil shale, peat, coal).
• Ores (ores of ferrous, non-ferrous and precious metals).
• Hydromineral (underground mineral and fresh water).
• Gemstone raw materials (jasper, rhodonite, agate, etc.).
• Mining and chemical raw materials (apatite, phosphates, mineral salts, borates, clays, etc.
• Non-metallic minerals (building materials).

From what has been described, it can be seen that with the improvement of the properties of the mineral lands, it is possible to grow ecologically clean fertile plants, since macro- and microelements are available in the right amount. These minerals are not used, as they contain nutrients in small quantities. On the other hand, despite the use of a large number of machines and mechanisms, as well as labor, minerals are used by 55-65%. The nutrients contained in the used sludge are not used in the required form [2, 3]. If you use them in a complex, then the existing element replaces the missing one. All this will lead to the production of a new product so that the manufactured product will meet the needs of the republic. However, currently the republic needs 160-170 thousand tons of fertilizers and meliorant used to bring the mortgaged lands into use. It is a pity that fertilizers are bought from abroad at an expensive price, and the lack of ameliorant leads to an increase in hectares of inhabited land. Despite all this, most of the nutrient-rich sludge is not used. It remains in the rain and sun becomes unusable, and also violates the ecological balance. Along with these minerals, as well as sludge with large reserves is not used for soil improvement. Therefore, currently in the republic, the development of technologies, such compounds and the expansion of areas of use is of great importance. In this regard, it is relevant. joint use of sludge and minerals.

About drilling mud dumped around drilling rigs continues to be a source of dust – in summer, and in winter the cause of waterlogging, both in mountainous and lowland areas. This causes disturbance of the ecological balance, pollution of habitat, pastures, atmosphere, hydrosphere and lithosphere and is the cause of various diseases. 80-100 m³ of sludge is obtained from each operating well during the period of operation. On the other hand, drilling slurries are distinguished by the presence of numerous macro- and microelements, and can be used in the production of complex fertilizers, meliorants and other modified compounds with plant protection properties. Rational use of cheap and inexhaustible raw materials – waste from various industries is also relevant. Despite the fact that there are stages of invention and materials in the current direction, which show the use in various fields of sludge waste and their solutions obtained from oil drilling [4, 5]. However, the utilization of these inventions and materials is insufficient for the use of the oil industry, in particular drilling sludge. It turns out that this is due to the fact that the soils of the republic always need chemical reclamation of disturbed agricultural lands. Also, at the same time, the use of inexhaustible and cheap waste as the main raw material, polluting the atmosphere, the hydrosphere, the lithosphere, which generally prevents a violation of the ecological balance [6].

The purpose of our research is to develop a technology of compounds that is important in the cultivation of environmentally friendly, more resistant to natural phenomena (cold, heat, wind) plants, increasing the productivity and fertility of stony, sandy, saline and swampy soils, rich in numerous nutrients, macro- and microelements of drilling mud and potassium-containing minerals [7]. This goal is achieved by shifting drilling mud and compounds containing potassium in a ratio of 2,5 ¸ З,5 : 0,3¸ 0,5.

At the same time, materials coming out of oil wells in the form of sludge with the following chemical composition were used (table 1).

Table 1. Chemical composition of materials coming out of oil wells in the form of sludge during drilling

The Siyazan deposit of the Republic of Azerbaijan was used as compounds containing potassium of the following composition (mass %): Na₂O 1.61-2.00; MgO 2.10-2.90; A1₂O₃ 9.86-10.50; SiO₂ 61.50-62.0; P₂O₅ 0.89-1.01; K₂O 1.89-3.41; CaO 1.66-1.79; TiO₂ 0.81-0.93; MnO 0.11-0.13; Fe₂O₃ 1.60-1.70; CT 0.69-0.75; total 99.9-100. Spent phosphoric acid from various industries contains (mass %): H₃PO₄ 10.0-15.0; NO₃ 5.0-7.0; ZnO 0.3-0.5; MnO 0.10-0.12; the rest is H₂O.

Depending on the conditions, the yield of the resulting product with granule sizes of 1-5 mm is 89-94% with the following composition of nutrients (% by weight, part): P₂O₅ 2.5- 3.1; K₂O 2.6-3.0; H₂O 9.9-10.1; trace elements (Si, Zn, Mg, etc.) – 0.11-0.17 and granule hardness 1.7-2.4 MPa. The meliorant obtained from the screw press consists of (mass. %): P₂O₅ 0.4- 0.6; K₂O 0.2-0.3; H₂O 2.6-3.1.

After separation of the solid and liquid parts, the amounts of P2O5, K2O were determined in both samples. Si, Zn, Mg and Mn. It was found that, depending on the concentration of acid, the duration of residence of the dilute solution in the reactor and the screw press, about 89-92% of nutrients. Siyazan clay and Darydag water turn into liquid, the rest into solid phases [8].

Analyses of the waste (materials) used and the products obtained were carried out by spectrophotometric, chromatographic, atomic absorption spectrometric (AAS) research methods.

Other experiments were conducted similarly, the remaining 1, with different amounts of components used. The results are shown in table 2.

Table 2. Results with different amounts of components used

The proposed method of joint use of drilling slurries, Siyazan Darydag water of Nakhichevan makes it possible:

- to be used for the first time in agriculture and food production;

- plants, inexhaustible reserves of drilling sludge;

- use as a raw material containing potassium, Siyazan clay;

- use as raw materials containing boron, zinc and other trace elements.

Darydag waters of Siyazan;

- for the first time to produce crushing of a mixture of drilling slurries and Siyazan clays

- for the first time to develop a technology for obtaining organic mineral fertilizers and meliorant modified with numerous trace elements using a universal technology based on drilling mud, Siyazan clay, H₃RO₄ diluted with water Siyazan containing boron.zinc and other trace elements.

One of the stable global trends in the production of mineral fertilizers in recent years is the rise in the production and consumption of complex magnesium fertilizers. The rise in the use of high-concentration fertilizers, the rise in productivity, and hence the rise in the use of nutrients, including magnesium in the soil, make the task of compensating for magnesium losses more and more urgent. The methods of obtaining complex magnesium fertilizers during acid processing of various types of magnesium-containing raw materials are known. In this article, we studied the method of obtaining magnesium-containing mineral fertilizer with certain chemical-physical properties.
The research was conducted to prepare magnesium-containing fertilizers based on several types of local raw materials and products. Information about the rheological properties of the obtained suspensions was obtained at this time, which, in turn, made it possible to justify the optimal conditions and methods of introducing components containing magnesium, nitrogen, and potassium into the technological process.
The acquisition of mineral fertilizer by breaking down dolomite, a magnesium carbonate raw material, with sulfuric acid of different concentrations in a wide range of concentrations (30-70%) and adding a nitrogen-containing component to the obtained slurry was studied in the research.Basically, at low concentrations of acid, the decomposition of dolomite is completed in a relatively short time, and at relatively high concentrations of acid, the time required for the decomposition of dolomite is slightly extended.
In the research, 30-70%, at 60°C temperatures of 30-70% and 60°C, slurries obtained from the decomposition of dolomite were used.
The degree of decomposition of the raw material was calculated using the hora sample taken during the decomposition of dolomite with sulfuric acid.
At the time of crystallization of various solid phases, the nature of the mineral, the rate and concentration of sulfuric acid, the precipitating properties of magnesium phosphate salts, and the speed and degree of decomposition in all M: B ratios were found to have a significant effect.
The obtained results show that in all cases, the increase in the rate of decomposition as a function of time manifests itself as an important feature of the process and is known to affect the existing regularity. The physicochemical basis of the processes occurring during the purchase of magnesium-containing complex fertilizers by splitting phosphate raw materials or dolomite with acid and adding a nitrogen-containing component to the reaction was studied. Based on the literature data, it was concluded that, based on the analysis of the technological processes for the production of mineral fertilizers and equipment, it is necessary to decompose phosphate and magnesium-containing raw materials with sulfuric acid, then neutralize the resulting phosphate acid suspension, granulate it, and obtain a complex magnesium-containing fertilizer by drying the finished product more convenient.
The increase in the use of high-concentration fertilizers, the increase in productivity, and, in connection with this, the increase in the output of nutrients, including magnesium, make the problem of compensation for magnesium losses more and more urgent. Based on numerous agrochemical studies, it has been proven that magnesium-containing fertilizers have a positive effect on both the volume and quality of the crop against the background of NPK [1].
During the studies, the physicochemical properties of the application of magnesium-containing components at different stages of the production of superphosphate and complex magnesium-containing fertilizers, and the mineralogical composition and physical-mechanical properties of the products formed at separate stages of the production of complex magnesium-containing fertilizers were studied.
The analysis of the known methods of obtaining magnesium-containing fertilizers shows that the most interesting method is based on splitting phosphorite with nitric acid, and then mixing nitric acid with urea and potassium chloride. Using sulfuric and phosphoric acids, the authors studied the possibilities of applying magnesium-containing raw materials at different stages of phosphate raw material decomposition [4].
One of the most popular mineral fertilizers in the world market, 15:15:15:5, was selected as the base brand of fertilizers, and this fertilizer is considered a balanced full-complex magnesium-containing fertilizer [5].
During the research, the effect of the duration and temperature of the magnesium-containing raw materials decomposition process with acid, as well as the concentration of sulfuric acid on the decomposition process and the main technical indicators were studied.
The combined application of dolomite with phosphate raw materials has hurt both the content of different forms of P₂O₅ and the degree of decomposition. The decomposition of phosphate raw materials decreases, which is related to the magnesium contained in dolomite, the negative effect of which on the process of acid decomposition of phosphate ores was also noted by other authors [2, 3].
The analysis of the obtained results allows us to conclude that dolomite should be included in the suspension formed after the decomposition of the main part of phosphorite. The consumption of sulfuric acid with the combined application of primary phosphorus- and magnesium-containing raw materials was calculated based on the condition of co-degradation of phosphorite and dolomite, therefore, if only phosphorite is included, the actual amount of sulfuric acid that causes the decomposition of raw materials at the beginning of the process turns out to be more.
Let’s take a look at the value of the decomposition rate of raw materials containing magnesium and phosphorus with sulfuric acid with a concentration of 66% at a temperature of 60℃ for 90 minutes. The value of the decomposition rate during the joint decomposition of dolomite and phosphorite is equal to 84.43. During the decomposition of dolomite and then the inclusion of phosphorite, the decomposition rate is equal to 90.25. In the case of the decomposition of phosphorite and then the inclusion of dolomite, the decomposition rate is equal to 92.38. As we can see, the greatest degree of decomposition is possible in the case of inclusion of dolomite after the decomposition of phosphorite.
The results of the study of the effect of temperature on the general decomposition rate of phosphorite in the presence of dolomite are given in figure 1. The maximum decomposition rate of 96.42% is achieved at a temperature of 90єС, but decomposition at this temperature is accompanied by a significant thickening of the suspension. This fact is related to the negative effect of the formed magnesium phosphates, which is confirmed by literature data. The introduction of an additional liquid phase, which is necessary to achieve sufficient fluidity, is not desirable, because it will lead to a violation of the balance and a significant increase in energy costs in the drying phase for the next cycle [4]. Taking this into account, the optimal temperature is 80 ° C, at which the degree of decomposition reaches 91.34% and the resulting suspension maintains its fluidity.
It was determined that during the first 90 minutes, the main amount of raw material is decomposed, then when the decomposition time increases to 180 minutes and more, the suspension thickens until the fluidity is completely lost. This is explained both by the formation of calcium sulfate particles formed during the decomposition of phosphate raw materials and by the process of formation of crystals that make further processing of the resulting suspension impossible according to the existing technology. Thus, the optimal duration of the process should be 90-120 minutes.
However, even under these conditions, the maximum degree of decomposition does not exceed 90-92% when using only sulfuric acid. To obtain a specific brand of fertilizer in terms of nitrogen content, it is necessary to study together the process of adding the nitrogen-containing component by the technological balances performed.

Fig.1. Effect of temperature on the process of sulfuric acid decomposition of magnesium- and phosphorus-containing raw materials

The analysis of the obtained data allows us to conclude that the decomposition coefficient increases from 5% to 7% during the joint decomposition with a mixture of acids compared to the decomposition using only sulfuric acid. is the organization of a process: keeping the concentration of sulfuric acid in the liquid phase at 55 masses %, primary decomposition of phosphate raw materials with a mixture of sulfuric and phosphoric acids, phosphorus – 22 mass %, and subsequent introduction of magnesium-containing raw materials (dolomite) into one of the last sections of the reactor. The decomposition temperature is 80°C, and the total duration of the decomposition stage is 90-120 minutes. Under these conditions, the total decomposition rate of raw materials reaches 96.42%.
Based on the conducted research, the following scheme is proposed: stepwise decomposition of phosphate and magnesium-containing raw materials with sulfuric acid, the introduction of urea – a nitrogen-containing component into the suspension (it is known that the introduction of urea as a nitrogen-containing component improves the rheological properties. Urea can be fed into the process at any stage However, it is better to introduce urea into the suspension after the decomposition stage, characterized by the lowest viscosity and maximum fluidity) [4].
Thus, two possible options are offered for the implementation of the technological process, which includes different methods and the sequence of application of reagents, namely:
1) after splitting the phosphorite concentrate with acid, first dolomite is added to the phosphate suspension, and then nitrogen-containing component-urea.
2) decomposition of dolomite with acid and all subsequent stages are carried out according to the previous option.
As previously identified by the authors, when NPK fertilizer is produced, various chemical reactions occur at separate stages of the process, including ammonium salts and potassium chloride exchange reactions, the formation of double salts (phosphates and sulfates), as well as urea co-hydrolysis and dehydration of phosphoric acid with polyphosphate formation. interactions occur [5]. The course of these reactions leads to the fact that the resulting fertilizers are a multicomponent system, and the application of magnesium compounds undoubtedly contributes to the occurrence of additional processes and the complexity of the phase composition of fertilizers.
All magnesium in the resulting fertilizer is soluble in water, when dolomite is used, water-insoluble magnesium compounds are also present, although the decomposition of dolomite with a mixture of sulfuric and phosphoric acids occurs almost comprehensively.
Since dolomite is introduced into the reaction mixture at the initial stage (after the decomposition of phosphate raw materials), the process of magnesium sulfate formation can be represented by the following reaction equation:

If the amount of sulfuric acid taken for the decomposition of dolomite is less than the above-mentioned interval amount, the degree of decomposition of raw materials will reduce. Taking more than the specified interval amount of sulfuric acid taken for dolomite decomposition cannot be considered appropriate, because it does not diminish the degree of dolomite decomposition, but instead rises the consumption of sulfuric acid.
From the conducted studies, it was determined that the size of the dolomite particles has a significant effect on the decomposition rate [6].
Processing with acids During the processing of magnesium compounds, magnesium goes into solution in the form of soluble salts. For example, during the decomposition of dolomite with sulfuric acid, almost all magnesium in the raw material goes into the liquid phase. Currently, the rate of decomposition of carbonate compounds of magnesium and calcium in raw materials is high.
The determination of the activity of H⁺ ions in both pure and solutions neutralized with magnesium allows us to conclude that the activity of hydrogen ions is not directly proportional to the degree of neutralization of the acid.

Conclusions
1. During the research, it was determined the possibility of obtaining phosphorus-magnesium fertilizers by replacing phosphate raw materials with dolomite to a certain extent.
2. Splitting of phosphorite and dolomite with the presence of sulfuric acid was carried out separately, and our main priority in doing this was to make better the initial cracking conditions of the raw materials taken. A new technological method was intented to propose by processing the horras which formed together during the process.

Engine oils play a significant role in maintaining the performance and longevity of internal combustion engines. The use of proper additives in the production of engine oils maintains engine cleanliness and impedes the formation of impurities. The dissolution of additives in the base oils leads to interaction with the base oil components. The composition of the base oil, as well as the degree of its purification, significantly affects the effectiveness of the additives in it [1, 2].

It is important to evaluate the interactions of additives with the hydrocarbon classes, such as polyaromatic hydrocarbons and tar-asphaltene substances. These classes of hydrocarbons are involved in the process of polycondensation and formation of high-temperature deposits. On the other hand, they determine the colloidal stability of additives [3, 4]. Polyaromatic hydrocarbons and resinous-asphaltene substances in the lubricants are in the state of associates which complicates the assessment of the interactions of additives with them [5-7].

Experimental Part

The high-temperature catalytic oxidation method was used to get the most informative indicators of lubricants operating at high-temperatures and to study the changes in the physicochemical properties of the lubricating oils [8-10]. The method simulates the oxidation (thermochemical transformation) of lubricants in the most stressed temperature part of the engine cylinder, which allows to test lubricants in the most severe operating conditions and predict its operation in the engine [10, 11].

In order to evaluate the high-temperature properties of base oils, six samples (three petroleum fractions, as well as their mixture and two synthetic base oils) were subjected to high-temperature catalytic oxidation for 180 min. at 230°C (Table 1.).

Table 1. High-temperature deposit forming tendency of base oils

Results and Discussion

Synthetic base oils (PAO-4 and PAO-8) possessed the least tendency to form deposits and destruction of the base stock. Increasing the boiling point of petroleum fractions leads to the rising of the deposits. The formation of the small amount of sediment in synthetic oils is due to the presence of free double bonds in PAO. The presence of branched hydrocarbons, as well as methylene groups undesirably affects the high-temperature properties of base oils [3, 12].

During the exploitation process aging of engine oil occurs which is accompanied by a change in the structural group composition. The alteration in the composition of the base stock was evaluated after three-hour oxidation of the residue >500^⸰C (Table 2).

The initial fraction contains 81.58 % of “desirable” components – naphthenic-paraffinic and monocyclic aromatic hydrocarbons. Hydrocarbons which are prone to sedimentation account for 18.42%. The following ratio is observed after the three-hour oxidation process: the “desirable components”- 64.85 %, deposit formers – 35.15% which comprise of 9.24 % asphaltenes and copper naphthenate.

Table 2. Structural group composition of residue >500^⸰C

In order to assess the effect of various groups of hydrocarbons on the formation of deposits the correlation coefficient (R) was determined for various hydrocarbon groups of petroleum fractions (Table 2).

The correlation coefficient characterizes the static relationship between two random variables. Assuming that a strict order relation is given on the values of the variables, then a negative correlation – is a correlation in which an increase in one variable is associated with a decrease in another variable, while the correlation coefficient can be negative; a positive correlation under such conditions – is a correlation in which a rise in one variable is associated with an increase in another variable, however, the correlation coefficient can be positive [13].

In the case of naphthenic-paraffinic hydrocarbons the correlation coefficient is negative, which indicates that with an increase in the content of these hydrocarbons, the amount of deposit in the oil decreases, however in the case of other groups of hydrocarbons, the correlation coefficient is positive. The closer the value of the correlation coefficient is to 1 the greater the influence of the group hydrocarbons has on the formation of high-temperature deposits [14].

Bicyclic hydrocarbons, polycyclic hydrocarbons and resins have the greatest deposit forming tendency (Fig.1).

Fig.1. Influence of structural-group composition of residue on the formation of high-temperature deposits:
1 – bicyclic aromatic hydrocarbons; 2 – polycyclic aromatic hydrocarbons; 3 – resins

Conclusion

The assessment of the oxidation of lubricants by the high-temperature catalytic oxidation method showed that as the base oil oxidizes, the amount of bicyclic, polycyclic hydrocarbons and resin increases, that causes the rising of the high temperature deposit forming tendency of lubricating oils. The branching degree of hydrocarbons and the presence of unsaturated bonds influence the formation process of high-temperature deposits in the synthetic base oils.

Lubricating oils play a significant role in the increasing of life expectancy of internal combustion engines. Moreover, proper lubrication is an important factor to maintain better performance of automotive engines [1].

Base oils and a variety of chemical additives are the essential components for formulation of automotive lubricants that impact the lubrication system of modern engines. Therefore, creation of the interaction with base oils and additives are crucial for the efficient use of engine oils [2, 3]. The base oil composition influences the effectiveness of the detergent-dispersant additives in automotive lubricants [4]. Detergent-dispersant additives are most common additives used in modern motor oils. Furthermore, they are essential component in order to formulate of any engine oils [4-6].

Commercial additives are a solution of the active substance in oil-solvent. Oil-solvent can be synthetic and petroleum oil [2, 7]. The composition of oil-solvent of commercial additives can contain paraffin-naphthenic, aromatic (monocyclic, bicyclic, polycyclic) hydrocarbons and resins [8]. Bicyclic, polycyclic hydrocarbons and asphaltene and resins components can decrease the effectiveness of the action of additives. They are in the form of associates in the base oil, therefore they complicate the interaction of base oils with additives [3, 7, 8].

Experimental Part

Two commercial additives, petroleum high alkaline calcium sulfonate and high alkaline calcium alkyl salicylate are used in the research.

Standard research methods were used for determination of alkalinity and kinematic viscosity of base oils. Analytical methods (change in electrical conductivity, determination of structural group composition of base oils) were used in order to evaluate the interactions between additives and base oil components [9-12].

The electrical conductivity method for measurement of hydrocarbon liquids was used to study intermolecular interactions in the additives colloidal systems and oil-oxidation products. Determination of electrical conductivity was carried out on an electrometric installation. Any slight change in colloidal systems is accompanied by a change in their donor-acceptor properties, that is reflected in the indicator of the electrical conductivity [9-11].

The determination of chemical group composition method is chromatographic method that provides the separation of the sample into 6 groups: paraffin-naphthenic hydrocarbons, monocyclic aromatic hydrocarbons, bicyclic aromatic hydrocarbons, polycyclic aromatic hydrocarbons, resins, asphaltenes. Moreover, the high-temperature catalytic oxidation method was used to study the changes in the physical and chemical properties of the base oils and to get the indicators of lubricants at high-temperatures [10, 11].

Results and Discussion

The solvent-oil of commercial additives contains resins, polycyclic and bicyclic aromatic hydrocarbons, which can reduce the effectiveness of the additives (active substance) [8]. The active substance was isolated from commercial additives prepared with petroleum oil-solvents using a steam solvent (precipitation and decantation). The isolated active substance was dissolved in PAOM synthetic oil and a “purified” additive was obtained.

“Purified” calcium sulfonate interacts with 40-45% of resins, while commercial calcium sulfonate practically does not interact with resins. The process of chemical interaction of the “purified” additive is influenced by a drop in electrical conductivity with an increase in the concentration of resins (Fig.1).

Fig. 1. Influence of resins on the electrical conductivity of calcium sulfonate

1 – synthetic oil-solvent; 2 – petroleum oil-solvent

A slight abrupt change in the electrical conductivity of commercial calcium sulfonate in the region of 40-80% resin concentration in the additive-resin mixture indicates a variation in the solvate layer of additives. However, the replacing of the oil-solvent of calcium salicylate causes not only the changing of reactivity of “purified” additive, but also its nature of the interaction (Fig. 2).

Fig. 2. Influence of resins on the electrical conductivity of calcium salicylate

1 – synthetic oil-solvent; 2 – petroleum based oil-solvent.

The chemical interaction with resins (20-22% in the mixture with an additive) occurs in the case of commercial calcium salicylate, that is indicated by a drop in electrical conductivity followed by a steady constant value of electrical conductivity. The interaction of “purified” calcium salicylate occurs in steps. At the first stage, as in the case of a commercial additive, chemical interaction occurs with resins (18-20%), that is indicated by a drop in electrical conductivity. A further increase in electrical conductivity in the resin concentration of 20–45% shows the occurrence of colloidal process-solubilization (second stage). So, the difference in the reactivity of additives depends on the composition of the oil-solvent.

Dissolution of additives in the base oil leads to the formation of a new solvate shell. Moreover, physical changes occur in the structure of the additives. These processes affect the colloidal stability, the effectiveness of the lubricant additives.

The greatest interaction occurs between additives and bicyclic, polycyclic aromatic hydrocarbons, resins. These groups of hydrocarbons are sources of high-temperature deposits, while their presence in the base oil increases the colloidal stability of the additives.

Sulfonates and salicylates additives contain “strongly” polar groups and under the action of an electric field they are deposited. Dissolution of such additives in the base oil causes the physical interaction between the polar components of the base oil (polycyclic aromatic and resinous substances). Furthermore, these interconnections lead to a decrease in the formation of high temperature oxidation and an improvement in the colloidal stability of the lubricant additives.

Conclusion

Commercial additives prepared on the base of synthetic oil-solvents perform their functions 20-30% more efficiently compared to similar additives prepared on the base of petroleum oil-solvents. Replacement of petroleum oil-solvents with synthetic oil-solvents leads to the increasing of the reactivity of sulfonates and salicylates additives.

Modern stringent environmental requirements for gasolines suggest the limitations of aromatic hydrocarbons by maintaining their high anti-knock characteristics [1-3]. One of the solutions of this problem is a conversion of straight run gasolines or natural gasoline from high-temperature dehydrocyclization to low-temperature isomerization process [1, 4-6].

The isomerization process of C₅-C₆ alkanes plays an important role in the production of modern gasolines with a low content of aromatic hydrocarbons [7-9]. The isomerization process has very high technical and economic indicators compared to other processes that increase the octane number of fuel [3-5, 10].

Isomerate is practically indispensable in the production of motor fuels that meet the latest environmental requirements. Straight-run gasoline or natural gasoline containing C₅-C₆ paraffin hydrocarbons are the main feedstocks for production of environmentally friendly high-octane gasoline components [6, 11-14]. Conversion of straight-run gasoline or natural gasoline on composite catalytic systems containing tungstated or sulfated zirconium dioxide (ZrO₂), zeolite (MOR, HZSM-5) can lead to the production of eco-friendly high-octane gasolines with limited content of aromatics [1, 15].

Experimental Part

The main objects of study were anion-modified composite catalysts containing H-zeolite, such as mordenite and anion-modified sulfated zirconium dioxide or anion-modified tungstated zirconium dioxide. Zeolites modification was carried out by decationization and dealumination, ion-impregnation of various metals such as nickel or cobalt [12]. Zeolite catalysts were promoted using metal ions of salts obtained from nickel (NiNO₃), cobalt (CoSO₄∙7H₂O) and zirconium ZrO(NO₃)₂∙2H₂O, tungsten (NH₄)₆H₂W₁₂O₄₀  as a source of active components.

The content of SO₄^2- and WO₄^2- ions was controlled using solutions with a given content of ions, and their content in the obtained samples was controlled by elemental analysis (Agilent Technologies 7700 Series ICP-MS). The amount of SO₃ and WO₃ on ZrO₂ in the final samples was 6.1 and 11.8%, respectively.

Comparative analysis of reactants and reaction products was carried out directly at the inlet and outlet of the reactor (on-line mode) and analyzed using the Perkin-Elmer Autosystem XL gas chromatograph.

Results and Discussion

Sulfated (tungstated) composite catalytic systems containing zirconium dioxide (ZrO₂), zeolite (MOR, HZSM-5) and cobalt, nickel can involve natural gasoline in isomerization process with an increasing of C₅-C₆ paraffin hydrocarbons resources [1, 16]. The composition of natural gasoline considerably affects the efficiency of the process.

Natural gasoline is a mixture consisting mainly of C₅-C₇ alkanes. Such hydrocarbon composition is quite acceptable for isomerization process of natural gasoline to increase the concentration of iso-C₅-C₆ high octane components.

The composition of natural gasoline: gaseous alkanes C₄-(5.4%), iso-C₅ (25.5%), n-C₅ (19.3%), iso-C₆ (18.2 %), n-C₆ (8.6%), C₇₊ - 22.7%. The conversion of natural gasoline was carried out at atmospheric pressure, in the temperature range of 150-200⁰C. Natural gasoline conversion over Со/HMOR/WO^2-₄ ZrO₂ catalyst is presented in table 1.

Table 1. Natural gasoline conversion over Со/HMOR/WO^2-₄ ZrO₂ catalyst: LHSV=2,5 h^-1; τ=30 min

Conversion of natural gasoline on composite catalyst which combines the properties of anion-modified zirconia and H-zeolite, leads to significant changes in the distribution of hydrocarbons. Moreover, the most important of these changes are consumption of C₇₊ alkanes (C₇₊ conversion); reduction of C_4- alkanes and accumulation of C₅-C₆ alkanes, including high-octane iso-pentane and dimethylbutanes.

C_4- consumption is observed in the temperature range of 150-200⁰C. However, the consumption of C₇₊ occurs in the range of 150-180⁰C. Moreover in this temperature range the amount of isostructural C₅-C₆ alkanes increases.

Table shows 2 the results of natural gasoline conversion on Ni/HMOR/SO^2-₄ ZrO₂ catalyst. Conversion of the natural gasoline on Ni/HMOR/SO^2-₄ ZrO₂ allows increasing of isostructural C₅-C₆ alkanes and normal C₆ components and decreasing of С₄-, С₆ and С₇ components. The increase in the content of these hydrocarbons is a consequence of a similar decrease in other hydrocarbons, especially C₇₊. Ni/HMOR/SO^2-₄ ZrO₂ can convert natural gasoline and straight-run gasoline components and considerably increase the iso-C₅, n-C₅ and iso-C₆ components which are high octane resources.

Table 2. Natural gasoline conversion over Ni/HMOR/SO^2-₄ ZrO₂ catalyst LHSV= 2 h^-1; τ=30 min; υ_H2 =30 ml/min

Table 3. Influence of temperature on natural gasoline conversion over Ni/HMOR/SO^2-₄ ZrO₂ catalyst LHSV= 2 h^-1; τ=30 min; υ_H2 =30 ml/min

Table shows 3 influences of temperature on natural gasoline conversion on Ni/HMOR/SO^2-₄ ZrO₂ catalyst. Conversion of the natural gasoline on Ni/HMOR/SO²₄ ZrO₂ enables to isomerize C₅ and C₆ alkane hydrocarbons and to involve heptane in the process. Natural gasoline undergoes significant enrichment with high octane components due to extremely low octane heptane components.

Table 3 shows that in one pass over the sulfated based composite catalytic system the research octane number of gasoline increases by 15-22 points. So, reformate compounding with the resulting mixture can be the best method for production of high-octane gasolines.

The possibility of using the H-zeolite/SO^2-₄ ZrO₂ and H-zeolite /WO^2-₄ ZrO₂ catalytic systems for the conversion of components of natural gasoline between the temperature range 150-200ºС enable to increase the concentration of isostructural C₅-C₆ hydrocarbons and involve C₇₊ alkanes in the catalytic conversion process. Furthermore, the involvement of C₇₊ hydrocarbons in the catalytic processoccurs without the formation of C₁-C₃ alkanes.

Conclusion

The results of this research showed that C_4- gaseous alkanes are consumed in the conversion process of natural gasoline by forming high molecular weight of hydrocarbons. Moreover, the conversion of natural gasoline over sulfated (tungstated) composite catalytic systems containing zirconium dioxide (ZrO₂), zeolite (MOR, HZSM-5) and cobalt, nickel can open perspective opportunity for conversion of natural gasoline and straight run gasoline from high-temperature dehydrocyclization to low-temperature isomerization process.