RU2125080C1 - Method of removing organosulfur compounds from hydrocarbon stock - Google Patents

Abstract

FIELD: petroleum processing and petrochemical industry. SUBSTANCE: purification of hydrocarbon stock from organosulfur compounds is accomplished via oxidation of these compounds by contacting liquid hydrocarbon stock with working solution, in particular, sulfuric acid aqueous solution containing vanadium in oxidation state exceeding its minimum oxidation state value, after which resulting mixture is separated to yield purified liquid hydrocarbon stock and exhausted working solution containing vanadium reduced to oxidation state below its maximum value, and working solution is then regenerated. The latter operation is performed by precipitating reduced vanadium in the form of solid precipitate containing vanadium sulfates and their hydrates, separating and thermally decomposing solid precipitate into solid vanadium oxide and gaseous heat decomposition products, dissolving vanadium oxide in exhausted working solution to give regenerated working solution containing pentavalent vanadium predominantly in the form of ions bound to oxygen, hydrogen, and sulfur ions and/or atoms, to water molecules and/or sulfuric acid residues, and also nondissociated vanadium oxide molecules and/or their colloid particles. Precipitation is carried out by saturation and subsequent supersaturation of exhausted working solution with reduced vanadium, which is accomplished by reduction of vanadium in higher oxidation state by organosulfur compounds present in hydrocarbon stock. Heat decomposition of vanadium sulfate and/or acid hydrates of vanadyl sulfate proceeds simultaneously with oxidation of sulfur dioxide into sulfur trioxide at 450 to 550 C. Working solution is saturated with pentavalent vanadium by dissolving vanadium oxide obtained upon heat decomposition of solid precipitate, working solution containing 4-12 (preferably 6-10) M sulfuric acid. Concentration of vanadium in oxidation state exceeding its minimum value is usually at least 0.01 that of concentration of saturated solution of metal ions in sulfuric acid solution. Liquid hydrocarbon material is brought into contact with working solution in emulsion conditions. Sulfur trioxide obtained is dissolved in water to form sulfuric acid solution that is further added to working solution. Sulfur dioxide oxidation is carried out in presence of oxygen and vanadium catalyst at 400-700 C. Exhausted working solution separated from hydrocarbon material is fried of gum-like oxidation products by centrifugation and/or filtration. Separated hydrocarbon stock is fried of acid components and gum-like oxidation products by centrifugation followed by filtration using inert or alkaline filter material. Purified hydrocarbon stock is then distilled. EFFECT: enhanced purification efficiency and reduced power consumption. 15 cl, 1 dwg, 1 tbl

Description

 The present invention relates to the purification of hydrocarbons containing sulfur compounds, and more particularly it relates to a process for the desulfurization of liquid hydrocarbons containing organosulfur compounds by oxidizing and sulfonating these organosulfur compounds using a liquid regenerated solution containing transition metals.

 For economic and environmental reasons, there is an increasing need for liquid hydrocarbon mixtures containing very low levels of sulfur, such as automotive fuel, in which the sulfur content does not exceed 0.03 weight. % (300 ppm) or even 0.003 weight. % (30 ppm).

 Currently, hydrotreating is most often used for industrial cleaning of oil distillates. Hydrotreating, as you know, provides almost complete removal of mercaptans, sulfides and disulfides from liquid hydrocarbons, but the use of hydrotreating to reduce the thiophene content to 30 ppm is limited by price, therefore, the sulfur content in fuels and hydrocarbon feedstocks remains quite high, for example, 0.1- 0.2 weight %

 Although it is possible to use a multi-stage hydrotreating process that uses a successively increasing partial pressure of hydrogen and noble metal catalysts to remove thiophenes and other hard-to-remove sulfur compounds in many cases, this is considered impossible due to the high cost of installation and operation of such a process.

 An alternative approach is to extract and absorb sulfur compounds using selective solid sorbents, but thiophenes have low reactivity and the proposed sorbents do not provide the necessary cleaning efficiency.

 Some analogues are also known for oxidative desulfurization of petroleum products.

An electrical method for refining petroleum products is described in US Pat. No. 3,915,819, MKI ⁶ C 10 G 27/00 (1975). In accordance with this method, oil or petroleum products are mixed with an ionizing organic solvent (for example, methanol, toluene, etc.) and this mixture is subjected to direct current with a density of not less than 0.0001 A / cm ² and a voltage of 2-120 B. In order to accelerate this process, an aqueous salt solution or a solution of alkali or alkaline earth metal bases is introduced into the feed, providing a pH of 8-12. The process is conducted in an electrolyzer having two platinum cylindrical electrodes with a certain ratio of the areas of the anode and cathode for at least 4 hours. Desulphurization efficiency can reach 90%. The disadvantages of the method include: (1) it is necessary to ensure constant monitoring of the process parameters, since the values of current density, voltage and pH change during the process; (2) high energy consumption (due to the high resistance of the electrolyte, most of the energy consumed is spent on heating the electrolyte); and (3) the process lasts at least four hours, due to the poor conductivity of the electrolyte, which does not allow the use of high current densities.

U.S. Patent No. 4,101,635 MKI ⁶ C 10 G 29/00 describes a method for oxidizing sulfur dioxide by contacting a gas containing sulfur dioxide and an oxygen-containing gas with an aqueous solution containing pentavalent vanadium and divalent manganese as an oxidation catalyst, wherein a calcium compound and an oxygen-containing gas are added into the aqueous solution, the resulting gypsum is separated and the purified aqueous working solution is recycled for use as an oxidation catalyst. This method is not suitable for refining petroleum products, as they can be oxidized in the presence of oxygen.

US Patent No. 3,793,171 MKI ⁶ C 10 G 29/00 describes a process for the destruction of oxidizable impurities in a gas stream by contacting this gas stream with an aqueous acid stream containing an electrolytically regenerated oxidizing agent, and electrolytic regeneration of this oxidizing agent to further process additional amounts of gas stream . It is indicated that cobalt in the valence state +3 (Co III) is the most preferred oxidizing agent, other acceptable metals having at least two different ion-valence states are chromium (Cr VI / III), manganese (Mn III / II) silver (Hell II / I) and cerium (Ce IV / III).

 This method is not suitable for refining petroleum products, since with a high oxidation potential of the ions used in excess of 1.3 V, not only organo-sulfur compounds but also hydrocarbons can be oxidized.

 RF patent N 2101320 (Bull. Inventory N 1, 1998) describes a method for purifying petroleum products from sulfur, in which the oxidation of organosulfur compounds occurs upon contact of the petroleum product with a sulfuric acid solution containing transition metals, including vanadium, previously oxidized in an electrochemical cell. The working solution is regenerated in an electrochemical cell. This method provides a deep purification of petroleum products from organosulfur compounds, including thiophenes, but the electrochemical oxidation of metal ions requires a large consumption of electricity.

 To date, however, no practical, inexpensive, and efficient process has been created for the purification of liquid hydrocarbons, such as oil distillates, used for fuel or as hydrocarbon feedstocks and containing hard-to-remove thiophene sulfur compounds.

 The technical problem solved by this invention is to increase the cleaning efficiency and improve the quality of the raw materials being cleaned while reducing energy costs for refining petroleum products.

This problem is solved in that the cleaning of liquid hydrocarbon raw materials from organo-sulfur compounds is carried out by their oxidation by contacting the liquid hydrocarbon raw material with a working solution, which is an aqueous solution of sulfuric acid containing vanadium, which is in the oxidation state in excess of its minimum oxidation state, separation obtained in as a result of contacting the mixture to obtain a purified liquid hydrocarbon feedstock and a spent working solution containing vanadium, reduced minutes to a degree of oxidation less than the maximum, followed by regeneration solution. The spent working solution is regenerated by precipitation of reduced vanadium from it in the form of a solid precipitate containing vanadium sulfate salts and hydrates of these salts, separation of the solid precipitate and its thermal decomposition into solid vanadium (V) oxide and gaseous products of thermal decomposition, dissolution of the obtained vanadium oxide (V ) in the spent working solution to obtain a regenerated working solution containing vanadium ions that are in the oxidation state in excess of their minimum oxidation state. The working solution contains pentavalent vanadium, mainly in the form of ions bound to ions and / or atoms of oxygen, hydrogen and sulfur and water molecules and / or acidic residues of sulfuric acid, as well as undissociated molecules of vanadium oxide (V) and / or colloidal oxide particles vanadium (V). A solid precipitate in the spent solution is precipitated by saturation and subsequent supersaturation of the solution with reduced vanadium. The solution is supersaturated with reduced vanadium by converting vanadium, which is in an oxidation state exceeding the minimum oxidation state, into reduced vanadium, pentavalent vanadium is reduced to tetravalent vanadium by oxidation of organosulfur compounds present in hydrocarbon feedstocks. Basically, vanadium is deposited in the solid precipitate, which is in the oxidation state +4 in the form of vanadyl sulfate and / or vanadyl sulfate acid hydrates. Vanadyl sulfate and / or acidic hydrates of vanadyl sulfate are thermally decomposed into vanadium (V) oxide and gaseous products containing sulfur dioxide and trioxide. The thermal decomposition of vanadyl sulfate is carried out in the presence of oxygen, with the simultaneous oxidation of sulfur dioxide to trioxide at a temperature of 450 to 550 ^o C. At a temperature of less than 450 ^o C, the thermal decomposition does not completely and very slowly, at a temperature of more than 550 ^o C a significant effect on the process decompositions have adverse reactions leading to the conversion of vanadium (V) to vanadium (IV). The working solution is saturated with pentavalent vanadium by dissolving vanadium (V) oxide obtained by thermal decomposition of a solid precipitate, the working solution containing 4-12 M sulfuric acid per liter of solution, mainly 6-10 M sulfuric acid per liter of solution. The concentration of vanadium, which is in an oxidation state exceeding the minimum in the working solution, is mainly not less than 0.01 of the concentration of a saturated solution of metal ions in an aqueous solution of sulfuric acid. Contacting the liquid hydrocarbon feed with the working solution is carried out, forming emulsions of the feed and the solution. Sulfur dioxide obtained by thermal decomposition of a solid precipitate is oxidized to sulfur trioxide, which is dissolved in water to produce sulfuric acid, and the latter is added to the working solution. Mostly sulfur dioxide is oxidized in the presence of oxygen and a vanadium catalyst at a temperature of 400-700 ^° C. At lower and higher temperatures, the degree of conversion of SO ₂ to SO ₃ becomes very small. The mixture obtained by contacting the liquid hydrocarbon feed with the working solution is separated by settling or centrifugation to obtain a purified liquid hydrocarbon feed, and the spent working solution is regenerated. Separated from the hydrocarbon feedstock, the spent solution before its regeneration is purified from the resinous products of hydrocarbon oxidation by centrifugation and / or filtration. If it is not possible for other uses, the resinous products formed during the oxidation of hydrocarbon materials are subjected to thermal decomposition and oxidation in the presence of oxygen together with the thermal regeneration of the solid precipitate, and the heat released during the oxidation of the resinous products is used to carry out exothermic decomposition reactions of the solid precipitate. The separated hydrocarbon feed is subjected to purification from acidic components and gummy oxidation products by centrifugation followed by filtration to obtain a purified liquid hydrocarbon feed, using a filter containing an inert material or alkaline material, and after filtration, the purified liquid hydrocarbon feed is distilled.

 Mostly liquid hydrocarbon feeds with a reduced content of unsaturated and oxygen-containing compounds, condensed aromatic structures and with an organosulfur content of less than 1000 ppm are subjected to purification. For this, liquid hydrocarbon feedstocks are preliminarily purified from unsaturated, oxygen-containing compounds and compounds including condensed aromatic structures. Preliminary treatment of liquid hydrocarbon feeds is carried out by hydrotreating.

 After filtering, the purified liquid hydrocarbon feedstock can be passed through a sorbent capable of sorbing acidic components and gummy oxidation products for additional purification. The purified hydrocarbon feed is subjected to further purification from acidic products by contacting it with an alkali solution, followed by separation from the alkali solution and distillation.

The purification of hydrocarbon feed is carried out mainly at concentrations in the working solution of sulfuric acid 44-64 wt.%, Pentavalent vanadium 0.5-1 wt.%, At a temperature of 15-25 ^o C and atmospheric pressure.

 As used herein, “hydrocarbon feed” refers to any motor fuel (eg, gasoline, diesel, jet fuel), petrochemical feed, and the like. in the form of specific petroleum fractions or specific hydrocarbons. Liquid hydrocarbon feeds refined using this process can be petroleum products made from petroleum and refined products: coal, oil shale or bitumen sands, etc., and are usually mixtures of liquid hydrocarbons containing organosulfur compounds.

 Preferred feedstocks for the present process are pre-treated so as to substantially reduce the content of heteroatomic compounds by hydrotreatment or other suitable pre-treatment technology that also reduces the content of unsaturated or gum-forming compounds.

 This is because the present process works on the oxidation of organosulfur compounds. Unsaturated or oxygen-containing compounds and condensed aromatic structures can also be oxidized, yielding various by-products (e.g. resins), thereby reducing the desulfurization selectivity. Thus, it is generally undesirable to use the present technology for the purification of motor fuels of ionic composition (for example, containing esters and alcohols). The present invention is primarily intended for the fine purification of hydrocarbons that have been hydrotreated (for example, motor fuels that meet current standards - i.e., sulfur content <1000 ppm and <10000 ppm), and which do not, or contain very little oxidizable compounds. In this case, the present process provides selective removal of residual sulfur-containing, oxygen-containing and nitrogen-containing compounds.

 In the present process, an aqueous solution of sulfuric acid is used as a carrier of pentavalent vanadium.

 Aqueous solutions of sulfuric acid were used to remove organo-sulfur compounds from oil products using the so-called "sulfuric acid purification". In this process, an aqueous solution of sulfuric acid with an acid content of 2.5 to 18 moles per liter (2.5-18 M) (which corresponds to 20-96 wt.% Acid) is used to remove various organo-sulfur, unsaturated or gum-forming compounds.

The results of comparative tests of the present process and sulfuric acid purification are as follows:
a) Regime of concentrated sulfuric acid (i.e. 15-18 M).

 Sulfuric acid of this concentration removed about 40-50% of organosulfur compounds, and the addition of pentavalent vanadium in the solution did not improve the cleaning efficiency.

 b) Diluted sulfuric acid regimen (i.e. 12-15 M). Standard sulfuric acid purification is practically ineffective against thiophenes at such concentrations of sulfuric acid, but the addition of pentavalent vanadium provides almost complete removal of all organo-sulfur compounds.

However, solutions of 12-15M H ₂ SO ₄ with pentavalent vanadium substantially oxidize hydrocarbons, especially unsaturated and containing condensed aromatic structures.

 c) Regime of diluted sulfuric acid (i.e. 4-12 M).

 Standard sulfuric acid purification is practically ineffective against thiophenes at such concentrations of sulfuric acid, but the addition of pentavalent vanadium provides almost complete removal of all organo-sulfur compounds. The best results were obtained for a concentration of sulfuric acid in the range of 6-10 M, while the maximum efficiency was observed in the range of 7-10.

 c) Mode of low concentration of sulfuric acid (i.e. <4 M).

 Thiophenes were not removed if sulfuric acid of such a low concentration was used, although mercaptans and sulfur-oxygen compounds were removed.

 So, the preferred working range for the concentration of sulfuric acid in the solution is 4-12 M, the most preferred range for the concentration of sulfuric acid (i.e., providing maximum efficiency) is 6-10 M.

 In the present process, pentavalent vanadium is in an aqueous solution of sulfuric acid, and organosulfur compounds are in the hydrocarbon feed. This solution and raw materials, in practical cases, are mutually insoluble and, when mixed, form a heterophasic system. Then it turns out that the inter-liquid boundary makes possible the oxidation of organosulfur compounds with pentavalent vanadium and subsequent reactions of these organosulfur compounds with water or sulfuric acid. The cleaning speed and cleaning efficiency are affected by the border area and contact time. Therefore, it is desirable to mix the feed and the working solution, for example, forming an emulsion so that they are in close contact.

 Any known method that provides a boundary can be applied in order to implement the present process of desulfurization. And any known method can be used to separate the refined oil product and the solution. The choice of type of extractor is determined mainly by economic considerations.

 Pentavalent vanadium used in the present process in solution can be in the form of ions, which act as electron acceptors taken from organosulfur compounds. These ions change their charge during this interaction, pentavalent vanadium turns into tetravalent, which requires solution regeneration.

 The preparation of the working solution and its subsequent regeneration is done as follows. First, a solution is prepared consisting, for example, of a 9 M aqueous solution of sulfuric acid and a dissolved vanadium salt, in which vanadium is in the highest oxidative state. This metal salt can be of any type, for example, chlorides. Since the basic solution is sulfuric acid, it is preferable to use vanadium sulfate or vanadium pentoxide. In this case, no new ions appear in addition to those involved in the chemical process of hydrocarbon purification and additional side reactions are eliminated.

A solution of V ₂ O ₅ in 9M H ₂ SO _{4 was} adjusted to saturation with pentavalent vanadium and contacted with the hydrocarbon feed. In the process of oxidation of organosulfur compounds, pentavalent vanadium turns into tetravalent. V ₂ O _{5 was} added to the solution, saturate it again with pentavalent vanadium and contacted with the hydrocarbon feed. These operations are performed until the solution is first saturated and then supersaturated with tetravalent vanadium, which is formed from pentavalent organo-sulfur compounds during oxidation. A supersaturated solution of four valence vanadium precipitates a solid precipitate containing vanadyl sulfates and their acidic hydrates. This precipitate is thermally decomposed at a temperature of 450-550 ^o C on V ₂ O ₅ and gases containing SO ₂ and SO ₃ . Vanadium pentoxide is dissolved in a working solution, which becomes saturated with pentavalent and tetravalent vanadium, and the solution is in contact with the oil.

An important circumstance is that although standard designations of ions, such as V4 +, V5 +, are used, ions do not exist in an aqueous solution in exactly the same form. These ions are bound to water molecules, hydroxyl (OH-), acid residues (SO ₄ ^2- , HSO ₄ ^- ) or oxygen, or form complexes of two or more ions. Due to the nature of the process for purifying liquid hydrocarbon feeds, such hydration shells around ions and their bonds with oxygen are very important factors in this process. It is impossible to specialize the exact structure or properties of these shells of these ions or their complexes due to the fact that they are subject to changes depending on parameters that are not controlled during the cleaning process, for example, the concentration of hydrogen ions (H +), which also changes during oxidation ions of organosulfur compounds. Therefore, the concentration of hydrogen ions, and, probably, the type and properties of vanadium ions also change in time and in the reaction volume. In addition, undissociated molecules of tetravalent and pentavalent vanadium compounds and colloids of their compounds may exist in solution.

 The present desulfurization process is not truly catalytic, since pentavalent vanadium is a chemical reagent that is consumed during the heterophasic contact of the solution and liquid hydrocarbon feed. The term "consumed" means that this reagent is transformed during the oxidation of organosulfur compounds to another form (namely, to ions in a lower oxidative state). As long as such vanadium (V) ions are present in the solution in contact with the feed containing organosulfur compounds, the oxidation of organosulfur compounds occurs. Therefore, the lower limit of ion concentrations in the solution can be considered to be slightly larger than zero (the operability of this process was demonstrated with a concentration of pentavalent vanadium as low as 0.002 moles per liter of solution).

 The rate at which pentavalent vanadium is consumed will be determined by the rate of purification. For example, if the feed contains 3000 ppm of sulfur (i.e., about 0.1 mole of sulfur per liter of feed), and this sulfur is present as thiophene derivatives, then 0.6-0.8 moles of electrons (i.e. 6- 8 electrons per sulfur atom) must be accepted by pentavalent vanadium from organosulfur compounds. It does not really matter what exactly the concentration of pentavalent vanadium is, for example, if the ion concentration is 0.1 mol per liter of solution, then 6 liters of solution is required to purify 1 liter of the raw material from sulfur, if this concentration is 10 or 100 times less then a proportionately larger solution is needed.

 However, this ratio also gives only an estimate of the specific ion flow rate due to the fact that sulfur may exist in the form of other organosulfur compounds in commercial hydrocarbon feedstocks, or there may be incomplete sulfur removal. Uncontrolled adverse reactions are also possible that affect the specific consumption of pentavalent vanadium. Therefore, a range of 10-20 is a reasonable rough estimate of the preferred range of consumable electrons per atom of sulfur removed.

 In accordance with the above and the fact that the concentration of vanadium in the sulfuric acid solution is a difficult to control parameter, the concentration of pentavalent vanadium in the solution can vary from slightly more than zero to the concentration corresponding to the saturation point in the solution. Several concentration values were experimentally tested.

 The greatest efficiency of the cleaning process is achieved using a saturated solution of pentavalent vanadium. This concentration of the working solution is optimal for the deposition of tetravalent vanadium in the spent solution.

Sulfur dioxide produced by thermal decomposition of a solid precipitate is oxidized in the presence of oxygen and a catalyst (for example, vanadium) in SO ₃ , which is dissolved in water and sulfuric acid is obtained. The latter is added to the working solution to maintain a given concentration in it (for example, 9 M H ₂ SO ₄ ). Upon contact of the working solution with hydrocarbon feed, sulfuric acid is consumed in the sulfonation reactions of organosulfur compounds and hydrocarbons and leaves the purification process together with the resulting gummy products. If sulfuric acid recovered after thermal decomposition of a solid precipitate is not enough to maintain a given concentration of the working solution, then concentrated sulfuric acid from another source is added to it.

 The present process is preferably carried out at ambient temperature. Regenerated sulfuric acid has an elevated temperature, and after it is added to the working solution, its temperature also rises. Higher solution temperatures will lead to higher oxidation rates and heterophase reactions at the hydrocarbon / solution contact. Also, higher temperatures affect the concentration of a saturated metal salt solution, thereby increasing the maximum allowed concentration of pentavalent vanadium in the working solution.

 All these effects are positive in terms of the efficiency of the cleaning process. But on the other hand, an increase in temperature will also lead to an increase in the rates of adverse reactions, thereby making the process less selective (for example, leading to a greater yield of resins). Therefore, lower temperatures, generally speaking, are preferable to improve the selectivity of the process, and the working solution is cooled before it contacts the hydrocarbon feed.

In principle, for each type of hydrocarbon feedstock, the optimal temperature range can easily be determined, depending on the selected performance criteria (for example, the minimum resin yield or energy consumption, etc.)
The drawing shows a diagram of a plant for the purification of hydrocarbon feed from organosulfur compounds.

An apparatus for purifying oil products from organo-sulfur compounds contains: a reactor 1 for mixing a purified oil product (hydrocarbon feed) from tank 2 and a working solution coming from solution preparation reactor 3. A reactor 4 is connected in series to the oil product outlet from the reactor 1 for mixing the oil product with an alkaline solution, a distillation column 5 and a tank 6 for pure oil product. A device 7 for separating a solid precipitate from a working solution, a unit 8 for thermal regeneration of a solid precipitate of a catalyst, a reactor 9 for dissolving a solid catalyst, and a refrigerator 10, the outlet of which is connected to a reactor 3 for preparing a solution, are connected in series to the outlet of the spent working solution from the reactor 1. To the gas outlet from the block 8 for thermal regeneration of the solid precipitate of the catalyst are connected in series the reactor 11 for oxidizing sulfur dioxide (SO ₂ ) to sulfur trioxide (SO ₃ ) and the reactor 12 for dissolving SO ₃ in water, the outlet of the solution from which is connected to reactor 9. To the block 8 thermal regeneration of a solid precipitate of the catalyst connected to the source 13 of the oxidizing agent, such as air, and a source of heat 14. An oxidizer source 15, such as air, is connected to the SO ₂ oxidation reactor 11 in SO ₃ . A water source 16 is connected to the reactor 12, and the gas outlet from the reactor 12 is connected to the exhaust gas 17 of the gaseous products of combustion. A source 18 of concentrated sulfuric acid (H ₂ SO ₄ ) is connected to the reactor 9. A source of cooling water 19 is connected to the refrigerator 10. A water source 20 is connected to the solution preparation reactor 3. A water source 21, a source of calcium hydroxide Ca (OH) ₂ and a source of a mixture of sodium hydroxide (NaOH) and sodium carbonate (Na ₂ CO ₃ ) are connected to the reactor 4, and the output of the solid precipitate from the reactor 4 is connected to the solid sedimentation tank 24. A heat source 25 and a cooling water source 26 are connected to the distillation column 5. The output of non-condensable gases from the column 5 is connected to the hood 27, the output of the heavy fraction of petroleum products to the tank 28 of the heavy fraction, and the output of solid sediment to the tank 29 for sediment. The output of the solution from the device 7 separation of solid precipitate from the solution is connected to the reactor 3 of the preparation of the solution, and the output of resinous substances with a capacity of 30 for resin.

 Installation for implementing the method of technology for refining petroleum products is as follows.

The oil product coming from tank 2 and containing organosulfur compounds is mixed in reactor 1 with an aqueous solution coming from reactor 3 and containing sulfuric acid and vanadium compounds in which vanadium has a different oxidation state. The oil product and the aqueous solution are mutually poorly soluble, therefore, a two-phase system is formed in reactor 1, and oxidation and sulfonation reactions of organosulfur compounds occur at the interface between the oil product and the aqueous solution, resulting in the formation of sulfonic acids and other organic compounds containing sulfur and oxygen. Vanadium compounds with an oxidation state of +5: V ₂ O ₅ , VO ²⁺ are converted into compounds with an oxidation state of +4: VOSO ₄ VO ²⁺ in these oxidation reactions of organosulfur compounds.

The products of oxidation and sulfonation of organosulfur compounds are surface-active substances (surfactants) that concentrate at the oil-product interface and partially dissolve in an aqueous solution, where their further oxidation to simple oxides can continue: CO ₂ , H ₂ O, SO ₂ . Therefore, organosulfur compounds are removed from the hydrocarbon phase and are either concentrated at the interface or transferred to an aqueous solution. The process of purification of an oil product from organosulfur compounds is essentially an extraction process with chemical reactions at the interface.

 Moreover, in the oxidation and sulfonation reactions at the oil-product interface, first of all, organo-sulfur and other heteroatomic organic compounds enter, i.e. the extraction process is selective for those types of compounds that must be removed from the oil product.

 The selectivity of the extraction process is determined by the difference in the rates of oxidation and sulfonation reactions for different types of organic compounds. The oxidation and sulfonation rates increase in a number of compounds: alkanes, cycloalkanes, arenes, alkenes, and organosulfur compounds. The rates of these reactions also depend on the number of carbon atoms in the hydrocarbon skeleton of organic compounds, and the number of cyclic structures. Organic compounds with a large number of carbon atoms and cyclic structures are oxidized and sulfonated faster than lighter compounds.

 In this technology, the oxidation and sulfonation of organic compounds occurs upon their contact with an aqueous solution containing sulfuric acid and vanadium compounds. When sulfonating organic compounds with sulfuric acid, the reaction products are compounds containing oxygen and sulfur, as well as water. Therefore, the rates of sulfonation reactions and the equilibrium composition of the products strongly depend on the concentration of sulfuric acid in the solution. Sulfuric acid is a water-absorbing reagent. The reaction rates and the yield of sulfonation products of organic compounds increase with increasing concentration of sulfuric acid in solution. However, the selectivity of the processes of oxidation and sulfonation at the same time deteriorates - at a concentration of sulfuric acid of more than 15 M (15 mol of sulfuric acid per 1 liter of solution), almost all organic compounds are sulfonated with the formation of resinous products.

Therefore, this technology uses solutions predominantly with a concentration of less than 10 M, and the rates of oxidation and sulfonation reactions of organosulfur compounds selectively increase due to the introduction of pentavalent vanadium compounds into the solution, which are catalysts for oxidation and sulfonation processes. Depending on the concentration of sulfuric acid, pentavalent vanadium in the solution can exist in various forms: unstable colloids V ₂ O ₅ , undissociated V ₂ O ₅ molecules, and V ions with different contents of oxygen and hydrogen atoms and various hydrated and sulfate shells.

Empirically established the following:
1. In the presence of pentavalent vanadium, noticeable sulfonation and oxidation of all types of organosulfur compounds occurs when the concentration of sulfuric acid is more than 4 M. In this case, pentavalent vanadium turns into tetravalent.

 2. In the concentration range from 4 M to 10 M sulfuric acid, when petroleum products containing organo-sulfur compounds come into contact with the regenerated working solution, sulfonation and oxidation of mainly organo-sulfur compounds occurs, and hydrocarbons are oxidized and sulfonated to a much lesser extent than organo-sulfur compounds. At the same time, alkanes, cycloalkanes and arenes with one benzene ring practically do not undergo sulfonation and oxidation. Alkenes can noticeably sulfonate and oxidize, but to a much lesser extent than organosulfur compounds. Condensed hydrocarbons containing two or more benzene rings (e.g. naphthalene) are oxidized and sulfonated to form dark tarry products.

 3. The conversion rates of organosulfur compounds are reduced in the series: mercaptans, sulfides, disulfides, thiophenes. When the concentration of sulfuric acid is less than 4 M, only mercaptans are removed from the oil product, at 4-7 M - sulfides, and at 7-10 M - thiophenes. At a sulfuric acid concentration of more than 10 M, all types of organosulfur compounds can be removed from the oil product, but at the same time, already noticeable sulfonation of hydrocarbons begins.

 4. The degree of conversion of organosulfur compounds upon contact of an oil product with a solution increases with an increase in the content of pentavalent vanadium in the solution, and it becomes greatest when the solution is saturated with pentavalent vanadium. The dependence of the solubility of pentavalent vanadium on the concentration of sulfuric acid is not monotonic in nature, therefore, the catalytic activity of saturated solutions of pentavalent vanadium also does not monotonically change with a change in the concentration of sulfuric acid from 4 M to 10 M.

 Thus, on the basis of experimental data, it was found that the method according to this invention has a predominant use for the purification of petroleum products and the selective removal of organo-sulfur compounds from alkanes, cycloalkanes and arenes having one benzene ring, and mixtures of such hydrocarbons.

 By selecting the parameters of the purification process, a sufficiently large degree of conversion of organosulfur compounds with low losses of hydrocarbons can be provided.

The extraction process, complicated by chemical reactions at the interface, cannot be calculated theoretically even when the mechanisms of these reactions are known. Therefore, for any design of reactor 1 (extractor), it will be necessary to experimentally select the parameters of the refining process for each type of refined oil product that provide the necessary cleaning depth (degree of conversion of hydrocarbons) with minimal product loss. These parameters include the following:
the concentration of sulfuric acid and pentavalent vanadium in the catalyst solution;
volumetric ratio of oil product / working solution;
effective solution – oil product interface;
the duration of contact of the oil with the solution.

 Of these parameters that are subject to experimental selection, the last two (border area and contact duration) are interrelated, and it will not be possible to independently change them in the installation for refining petroleum products. In the design of reactor 1, it is necessary to provide for the possibility of changing these two parameters, for example, by changing the intensity of mixing the solution and the oil product, but it is advisable to make the main regulation of the cleaning process by changing the concentration of the working solution and the volume ratio of oil product to solution.

 With the optimal selection of the parameters of the purification process, sulfonic acids will form in reactor 1, which can partially transfer to the working solution, partially concentrate at the interface, and partially transfer to the refined oil product. Therefore, simultaneously with the removal of organic sulfur from the oil product, inorganic sulfur from the solution will fall into it due to sulfonation of hydrocarbons and, in addition, sulfuric acid can be dissolved in small amounts in the oil product. In cases where the content of organic sulfur in the initial oil product is small (less than 0.5%), after contact of the oil product with the regenerated working solution, the total sulfur content in the oil product (organic and inorganic) may even increase. However, sulfonic acids and sulfuric acid dissolved in the oil product can be easily removed from them by extraction with an alkaline solution. For this, the oil product after its contact with the regenerated working solution from the reactor 1 is fed into the reactor 4 for mixing the oil with an alkaline solution.

In this reactor 4, acidic products containing sulfur are transferred to an aqueous solution containing hydroxide and sodium carbonate. In this case, sulfuric acid and sulfonic acids form sodium salts in the solution, and the solution is neutralized (the pH value decreases). To restore the alkaline nature of the solution in the reactor 4, calcium hydroxide is fed into it from a source of 22 Ca (OH) ₂ . Calcium ions Ca ²⁺ form poorly soluble salts with acidic residues of sulfuric acid and sulfonic acids, which precipitate and are removed from reactor 4 into a solid sedimentation tank 14. As a result of reactions of calcium hydroxide with salts of sulfonic acids, the alkaline nature of the solution in reactor 4 is restored (the pH value increases), the solution is continuously regenerated and continues to extract acid residues from the oil product fed to reactor 4.

 Poorly soluble calcium salts precipitate in the form of a wet precipitate, in which sodium ions and carbonate ions may be present. Therefore, together with the precipitate from the reactor 4 in the tank 24 will be carried out water, hydroxide and sodium carbonate. To make up for the losses of these reagents, water, sodium hydroxide and sodium carbonate are supplied to the reactor 4 from sources 21 and 23.

 The oil product withdrawn from reactor 4 may contain sodium salts of sulfonic acids, so it is fed to distillation column 5. When the oil is distilled in column 5, sulfonic acid salts will either precipitate or decompose at the boiling point of the oil to form sodium sulfite and sodium sulfate and unsaturated hydrocarbons. The latter can partially dissolve in the pure oil product and enter the tank 6 of the pure oil product, or after thermal decomposition and polymerization processes occurring in different parts of the column 5, can be removed in the form of gases in the hood 27 or in the form of heavy polymerization products into the tank 28 of the heavy fraction.

Thus, the refining process consists of the following stages:
oxidation and sulfonation of organosulfur compounds and some (small) part of hydrocarbons upon contact of the oil in reactor 1 with an aqueous solution containing sulfuric acid and pentavalent vanadium;
extraction of oxidized and sulfonated organosulfur compounds in an aqueous solution or their concentration at the interface in the reactor 1 in the form of resinous substances sparingly soluble in hydrocarbons;
separation of oil in the reactor 1 from the working solution and resinous substances;
extraction from the oil product of the sulfonic acids and sulfuric acid remaining there with an alkaline solution in the reactor 4;
final distillation of the oil in the distillation column 5 with the removal of salts of sulfonic acids, residues of tar and water.

 The remaining elements of the installation for refining petroleum products are designed for continuous regeneration of the catalyst (pentavalent vanadium and sulfuric acid) and they work as follows.

The working solution together with resinous substances from the reactor 1 is fed to a device 7 for separating a solid precipitate from the solution. Since pentavalent vanadium is converted to tetravalent in reactor 1, the solution entering device 7 is supersaturated with the salts of tetravalent vanadium, and they precipitate in the form of hydrated vanadyl sulfate 2VOSO ₄ • H ₂ SO ₄ or hydrates of tetravalent vanadium salts of a different composition.

 The density of the working solution is greater than the density of resinous substances containing sulfonic acids, but less than the density of hydrates of salts. Therefore, the device 7 can be made in the form of a sump, in which the solution received from reactor 1 is stratified into three phases: the upper solid or liquid phase is resin, the liquid solution and the lower solid phase are hydrates of vanadium salts. Centrifuges can be used to speed up the process of dividing the solution into three phases. In any case, the liquid phase from the device 7, which is a saturated solution of tetravalent vanadium, is fed into the reactor 3 to prepare the working solution. The resin is discharged into the resin container 30 and may then be a by-product of the product, since sulfonic acids, which are surfactants, are present in it.

Solid hydrates of vanadium salts, together with part of the supersaturated solution and possibly contaminated with tarry substances, enter block 8 for thermal regeneration of the solid catalyst, which also supplies air or oxygen from oxidizer source 13 and heat from source 14. In block 8 at a temperature of 450-550 ^o C the solid precipitate is first decomposed into dry vanadyl sulfate VOSO ₄ , sulfuric acid and water, and resinous substances in the presence of air are oxidized to simple oxides: CO ₄ , H ₂ O, SO ₂ . The heat released in this case is spent on heating the solid precipitate and the endothermic reaction of its decomposition.

 If the resin coming from the device 7 into the container 30 cannot be used as a commercial product, it is advisable to supply it together with a solid precipitate of hydrated salts to block 8. Then the heat released during the combustion of the resin may suffice for all endothermic reactions flowing in block 7, and the heat source 14 will be used only when starting the installation from a cold state.

Solid vanadyl sulfate formed during the decomposition of hydrates of salts at a temperature greater than 450 ^o C quickly decomposes by reaction
2VOSO ₄ = V ₂ O ₅ + SO ₂ + SO ₃ ,
or in the presence of oxygen by reaction
4VOSO ₄ + O ₂ = 2V ₂ O ₅ + 4SO ₃ .

 The resulting vanadium pentoxide is a regenerated solid catalyst and enters the solid catalyst dissolution reactor 9.

Gaseous products from block 7, containing CO ₂ , H ₂ O, SO ₂ and SO ₃ , enter the SO ₂ oxidation reactor 11 in SO ₃ , where they are oxidized in the presence of air from sources 15 and a catalyst, for example vanadium pentoxide. In gaseous products, only SO ₂ and products of incomplete combustion of the resin, for example, CO and CH _x , can be oxidized, which can be formed in block 7 due to the lack of oxidizing agent coming from source 13. The temperature in reactor 11 is maintained in the range of 500-700 ^° C. An additional source of heat is not required for this, since the temperature of the gases leaving the unit 7 is 450-550 ^o C, and the oxidation reactions in the reactor 7 are exothermic. To prevent overheating of the reactor 11, it may be necessary to remove heat into the environment.

Gaseous products containing SO ₃ enter from the reactor 11 into the reactor 12 for dissolving SO ₃ in the water coming from the source 16. The hot sulfuric acid resulting from the dissolution of SO ₃ in water enters the solid catalyst dissolution reactor 9. Gaseous products, practically free of sulfur oxides, are released into the environment using exhaust hood 17.

 Thus, the purification process is closed by the catalyst, since pentavalent vanadium and sulfuric acid are regenerated. These reagents, mainly sulfuric acid, can leave the closed loop of oil product purification together with solid precipitates entering containers 24 and 29 and with resin entering tanks 30. To compensate for these losses, pentavalent vanadium in the form of pentoxide can be added to the solid catalyst coming from block 8 to reactor 9, and sulfuric acid enters this reactor from source 18.

 In the reactor 9, solid vanadium pentoxide dissolves in the hot sulfuric acid coming from the reactor 12 and the source 18. The concentration of sulfuric acid and its flow from the source 18 are controlled so that the acid content in the solution 9 is 10-12 M, and a saturated solution of vanadium pentoxide formed.

 The solubility of vanadium pentoxide in sulfuric acid has a maximum at a sulfuric acid concentration of about 11 M. A saturated solution with a maximum content of vanadium pentoxide is cooled in the refrigerator 10 with water coming from the cooling water source 19 and mixed in a reactor 3 with a solution saturated with tetravalent vanadium vanadium. coming from the device 7. The reactor 3 also receives water from the source 20 in the amount necessary so that at the outlet of the reactor 3 the concentration of sulfuric acid is equal to 6-10 M.

 Thus, a solution with a given concentration of sulfuric acid and close to saturation with pentavalent and tetravalent vanadium enters from reactor 3 into reactor 1. Oxidation reactions occur in reactor 1, in which pentavalent vanadium is converted to tetravalent, and the working solution from reactor 1 to device 7 becomes supersaturated. In this device, tetravalent vanadium precipitates and the catalyst regeneration cycle closes.

 As noted above, it is advisable to regulate the depth of refining of the oil product (the degree of conversion of organosulfur compounds) and minimize hydrocarbon losses by changing the volume ratio of the oil and working solution entering reactor 1. The value of this volume ratio must be selected empirically for each type of refined oil product, taking into account the value allowable losses of the oil product, the initial content of organic sulfur in it and the required final content of total sulfur in the purified oil product.

 When designing the installation, it is necessary to know the average value of the volume ratio of the oil product / solution or the limits of the change in this ratio when cleaning the oil product with a given sulfur content. Such estimates can be made as follows.

 The reaction mechanisms of organosulfur compounds with a regenerated working solution have not yet been sufficiently studied, but in any of these mechanisms the sulfur atom entering into organosulfur compounds is oxidized. In organosulfur compounds that make up various petroleum products, sulfur can have varying degrees of oxidation from -2 to +6. If sulfur is in an oxidation state of +4 or +6, then the organosulfur compounds are sulfonic acids or other acidic compounds that will be removed from the oil when it comes into contact with an alkaline solution in reactor 4. Such compounds in reactor 1, when the oil comes in contact with the regenerated working solution, can sulfonated with sulfuric acid to form polybasic sulfonic acids. Pentavalent vanadium from the solution will not be consumed in significant quantities in these reactions, and sulfuric acid in the catalyst solution will always be in large excess with respect to organosulfur compounds. Therefore, the sulfonation of organosulfur compounds in which sulfur is in the oxidation state of +4 or +6 cannot significantly affect the optimal value of the volume ratio of oil product / working solution in reactor 1.

The main target consumption of pentavalent vanadium from the solution will be associated with the oxidation of divalent sulfur contained in organosulfur compounds to an oxidation state of +4 or +6. In such reactions, 6-8 moles of pentavalent vanadium will be consumed per 1 mol of organic sulfur, which is in the oxidation state of -2. For example, during the oxidation of octyl mercaptan, the gross reaction will be as follows:
C ₈ H ₁₇ SH + 3V ₂ O ₅ + 6H ₂ SO ₄ = C ₈ H ₁₇ -SO ₃ H + 6VOSO ₄ + 6H ₂ O,
that is, 3 moles of vanadium pentoxide or 6 moles of pentavalent vanadium are consumed per 1 mole of sulfur.

During the oxidation of individual organo-sulfur compounds by the regenerated working solution, this gross reaction equation is rather well satisfied. A quantitative estimate of the pentavalent vanadium consumption necessary for the oxidation of organic sulfur was carried out for several organo-sulfur compounds. For example, 4.2 g of octyl mercaptan, which is 0.03 M, and 17.1 g of vanadium pentoxide, which is 0.19 M of pentavalent vanadium dissolved in 9 M sulfuric acid, were taken. Vanadium was taken with a 5% excess, since 0.03 M octyl mercaptan requires 0.09 M vanadium pentoxide and 0.18 M pentavalent vanadium to oxidize. After the working solution was in contact with octyl mercaptan, the latter completely oxidized, pentavalent vanadium almost completely turned into tetravalent, which could be judged by the color change of the solution, and VOSO ₄ • H ₂ SO ₄ acid vanadyl sulfate hydrate (light blue crystals) precipitated, after calcination of which vanadium pentoxide formed.

 Thus, if the exact mechanism of reactions of the working solution with organosulfur compounds is unknown, it can be assumed that the gross reaction equations similar to the above, which can be written for each organosulfur compound, are satisfied, and based on such equations, the pentavalent vanadium consumption in the target reactions can be estimated oxidation of organosulfur compounds.

If only such target reactions occur in reactor 1, and all sulfur in the organosulfur compounds has an oxidation state of -2, then the volume ratio of oil product / working solution should be equal
V _n / V _p = (m _s ρ _p c _v ) / (m _v ρ _n c _s k),
where V _n Vp _p - the volume of oil and working solution;
m _s , m _v - atomic weights of sulfur and vanadium;
c _s - mass content of sulfur in the oil product;
with _v is the mass content of vanadium in the catalyst solution;
ρ _p , ρ _n - the density of the oil and solution;
k = 6 or 8 is the stoichiometric coefficient in the equation of gross oxidation reactions of the organosulfur compound.

For example, with c _s = 0.002 (0.2%), c _v = 0.02 (1% saturated solution of vanadium pentoxide in 7 M sulfuric acid) ρ _p and ρ _n = 850 and 1390 kg / m ³ (density a solution of 7 M sulfuric acid), k = 6, the volume ratio will be equal to V _n / V _p = 0.86.

 Petroleum products are complex systems for investigating the understanding of the processes that occur during the purification of petroleum products from organosulfur compounds, optimizing the refining process, therefore, model mixtures imitating hydrocarbon raw materials were used for a specific process. Toluene, heptane, dodecane, ethyl cyclopentane, hexene and naphthalene (25%) in toluene with thiophene additives (2.5%) were taken as model mixtures.

 For such mixtures, the inorganic sulfur content in the product that got into the oil from the working solution was determined as the difference between the total sulfur content determined by the burning method and the organic sulfur content determined by the chromatographic method.

Processing the regenerated working solution (saturated solution of V ₂ O ₅ in 8-9 M H ₂ SO ₄ ) was carried out under the same optimal conditions, selected experimentally. The process was carried out for 40 minutes with stirring with a magnetic stirrer. To treat 40 ml of the mixture, 200 ml of working solution was used. Before and after treatment with the regenerated working solution, a sulfur analysis (quartz tube burning method) and thiophene analysis (chromatographic method) were performed.

 It was found that the total amount of sulfur increased after the contact of hydrocarbon mixtures with the solution, and the concentration of thiophene decreased in all model mixtures to values less than 0.05%. This allowed us to conclude that the mixture contained in the form of catalyst residues in a pure or bound form, and after processing the model mixtures with a solution with a catalyst, almost all of the sulfur contained in them got from the solution, and the organic (thiophene) was removed.

 During the purification in the case of toluene, heptane, dodecane and ethylcyclopentane, no noticeable changes were observed in the mixtures, while in the presence of naphthalene there was a reddening of the solution, the latter is probably associated with the oxidation of naphthalene to naphthoquinones. In the case of hexene, a rapid change in the color of the catalyst occurred (almost complete reduction), which is probably due to the oxidation of the double bond of the unsaturated compound. Since the concentration of sulfuric acid in the catalytic solution is large, sulfonation could be expected during the processing of the toluene mixture with the formation of sulfonic acid. However, toluene was resistant to oxidation and sulfonation upon contact with the regenerated working solution.

 Several methods of additional purification of the oil product from impurities of the catalyst and sulfur-containing components were used. Samples of the treated mixtures (5 ml) were further purified by the following methods.

 1. Rinse with saturated soda solution for 20 minutes.

 2. Rinsing with an alkali solution (20% NaOH) for 20 minutes.

 3. Processing with dry soda (shaking) for 20 minutes, followed by distillation of the hydrocarbon.

 4. Processing with dry alkali (shaking in a quartz flask) for 20 minutes, followed by distillation of the hydrocarbon.

 5. Rinsing with a solution of alkali or soda, followed by separation of the solution and hydrocarbons and distillation of hydrocarbons.

 The results of these experiments are shown in the table.

 As can be seen from the above data, the treatment with an alkali solution followed by distillation can be considered a quite suitable additional purification method, which allows us to bring the sulfur content to 0.02-0.03%.

Claims (15)

 1. The method of purification of liquid hydrocarbon raw materials from organo-sulfur compounds by oxidation by contacting liquid hydrocarbon raw materials with a working solution, which is an aqueous solution of sulfuric acid containing vanadium, which is in the oxidation state in excess of its minimum oxidation state, separation of the mixture obtained by contacting with obtaining a purified liquid hydrocarbon feedstock and a spent working solution containing vanadium, reduced to an oxidation state less than maximum, followed by regeneration of the solution, characterized in that the spent working solution is regenerated by precipitation of reduced vanadium from it in the form of a solid precipitate containing vanadium sulfate salts and hydrates of these salts, separation of the solid precipitate and its thermal decomposition into solid vanadium oxide (V) and gaseous products of thermal decomposition, dissolution of the obtained vanadium (V) oxide in the spent working solution to obtain a regenerated working solution containing vanadium ions, yaschiesya in oxidation state higher than its minimum oxidation state.  2. The method according to claim 1, characterized in that the regenerated working solution contains pentavalent vanadium.  3. The method according to claim 1, characterized in that the solid precipitate in the spent solution is precipitated by saturation and subsequent supersaturation of the solution with reduced vanadium.  4. The method according to claims 1 to 3, characterized in that the solution is supersaturated with reduced vanadium by converting pentavalent vanadium to reduced vanadium during the oxidation of organosulfur compounds in hydrocarbon feedstocks.  5. The method according to claims 1, 2 and 4, characterized in that vanadyl sulfate and / or acidic vanadyl sulfate hydrates are precipitated into a solid precipitate.  6. The method according to PP. 1 and 5, characterized in that the vanadyl sulfate and / or acidic hydrates of vanadyl sulfate are thermally decomposed into vanadium (V) oxide and gaseous products containing sulfur dioxide and trioxide.  7. The method according to claim 1, characterized in that the thermal decomposition of the solid precipitate is carried out in the presence of oxygen. 8. The method according to claim 6, characterized in that the thermal decomposition is carried out at 450 - 550 ^o C.  9. The method according to claims 1 and 2, characterized in that the regenerated working solution is saturated with pentavalent vanadium by dissolving vanadium (V) oxide obtained by thermal decomposition of a solid precipitate.  10. The method according to claim 1, characterized in that the regenerated working solution contains 6 to 10 M sulfuric acid per liter of solution.  11. The method according to claim 6, characterized in that the sulfur dioxide obtained by thermal decomposition of a solid precipitate is oxidized to sulfur trioxide, which is dissolved in water to produce sulfuric acid, and the latter is added to the regenerated working solution.  12. The method according to claim 1, characterized in that the purified hydrocarbon feedstock after contact with the regenerated working solution is subjected to further purification from acidic components and gummy oxidation products by filtration through a filter containing an inert or alkaline material.  13. The method according to claim 1, characterized in that the spent solution separated from the hydrocarbon feedstock before its regeneration is cleaned of resinous products of hydrocarbon oxidation by centrifugation and / or filtration.  14. The method according to claim 1, characterized in that the resinous products formed during the oxidation of hydrocarbons are subjected to thermal decomposition and oxidation in the presence of oxygen together with the thermal regeneration of the solid precipitate, and the heat released during the oxidation of the resinous products is used to carry out exothermic reactions decomposition of solid sediment.  15. The method according to claim 1, characterized in that the purified hydrocarbon raw material after contact with the regenerated working solution is subjected to further purification from acidic products by contacting it with an alkali solution, followed by separation from the alkali solution and distillation.

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