Petroleum pitch and method of its production

Abstract

FIELD: petroleum and petrochemical industries.SUBSTANCE: production of petroleum pitch for the oil refining and petrochemical industries. Petroleum coke is added to the highly aromatic petroleum residue, and the resulting mixture is subjected to heat treatment at an elevated temperature for a specified time. After completion of the reaction, finely dispersed petroleum coke is removed by settling and / or filtration. To obtain petroleum pitch of electrode quality, the homogeneous product is thermally stabilized to a constant weight. The petroleum pitch obtained by the proposed method is characterized by a certain mass ratio of components (petroleum coke: highly aromatic petroleum residue) in the established range.EFFECT: invention consists in expanding the raw material base of petroleum binder pitches while maintaining the quality indicators required for electrode pitch.4 cl, 3 tbl, 14 ex

Description

[0001] The group of inventions relates to the field of oil refining, in particular to the production of petroleum binder electrode pitch, and can be used in the oil refining, petrochemical, aluminum industries and in the production of structural carbon materials.

[0002] The primary method for producing electrode pitch is the distillation of coal tar, a byproduct of high-temperature coking of coal. In addition to the aluminum industry, which consumes coal tar pitch for the preparation of anode paste and prebaked anodes, it is also used in the production of graphite electrodes, carbon structural materials, and pitch coke.

[0003] Depending on the combination of softening point, content of substances insoluble in toluene and quinoline, mass fraction of volatile matter and coke number [GOST 10200], electrode pitch is used for the production of structural carbon materials, electrode products and electrical goods (grade A), for general-purpose electrode products (grade B) and for the aluminum industry (grades B1, V and V1). The greatest consumption falls on grades B1 and V, which must have a softening point in the range of 72-76 and 85-92 °C (ring and rod method), respectively, a mass fraction of substances insoluble in toluene (α-fraction) of at least 26% and a mass fraction of substances insoluble in quinoline (α1-fraction) of at least 12%. In this case, the coke number of the pitch must be at least 53%.

[0004] The global trend towards a reduction in the consumption of metallurgical coke and the associated reduction in coal tar production leads to the need to search for alternative carbon binders.

[0005] One such alternative is petroleum pitch.

[0006] A method for producing petroleum pitch by vacuum distillation of thermal cracking resin from petroleum products is known [patent RU2288251, published November 27, 2006]. The resulting pitch has a softening point of 133°C, a viscosity of 11818 MPa⋅s at 180°C, and a coke residue of 53.7%. The high viscosity and softening point prevent the use of petroleum pitch as a binder for the production of anode mass and anodes for aluminum electrolytic cells.

[0007] Methods for producing petroleum pitches by thermal polycondensation of highly aromatic petroleum residues, such as heavy pyrolysis resin, thermal cracking residue and heavy catalytic cracking gas oil, are known [patents RU No. 2478685, published 10.04.2013; RU No. 2075496, published 20.03.1997; RU No. 2645524, published 21.02.2018; RU No. 2659262, published 29.06.2018; RU No. 2663148, published 01.08.2018; RU No. 2647735, published. [March 19, 2018]. The resulting pitches, depending on the technology used, have a wide range of softening temperatures from 70 to 155°C, with an absence of the α1-fraction (substances insoluble in quinoline) and a low content of the α-fraction (substances insoluble in toluene) of 10-18%. The low content of the α-fraction and the absence of the α1-fraction limit the use of petroleum pitch as a binder for the production of anode paste and anodes for aluminum electrolyzers.

[0008] Thus, a method is known for producing petroleum pitches [RU No. 2830635, published 25.11.2024] by thermal polycondensation of highly aromatic residual products of oil refining and / or their fractions with an initial boiling point of 200°C in an inert atmosphere at a temperature of 350-500°C and an elevated pressure of 0.2-1.5 MPa and with stirring in the first stage and isothermal holding at a temperature of 350-500°C and a reduced pressure of 0.001-0.01 MPa in the second stage and separating the resulting product into pitches with a high and low mesophase content. Heavy pyrolysis resin and heavy catalytic cracking gas oil are used as raw materials. This produces pitches with a softening point of 167°C and higher.

[0009] A known method for producing petroleum pitches [RU No. 2477744, published 20.03.2013] includes thermal polycondensation of heavy pyrolysis resin in a flow reactor at an elevated pressure of 1.0-2.5 MPa and a temperature of 330-400°C, maintaining the reaction mass at a temperature of 340-380°C for 3-10 hours in the presence of superheated water vapor, followed by vacuum distillation. This produces a high-temperature pitch (softening point 192°C) with an α-fraction content of 29.6% and an α1-fraction of 0.0%.

[0010] The disadvantages of known methods for producing petroleum pitch include the multi-stage and time-consuming thermal polycondensation processes, and the resulting pitch is used as a binder and fiber-forming pitch. The absence of quinoline-soluble substances in petroleum pitches obtained by thermal polycondensation of petroleum residues, the low content of toluene-insoluble substances, and the combination of a high softening point and a relatively low coking number prevent them from being used as an alternative to B1 and B grade coal tar pitches.

[0011] Various finely dispersed carbon additives can be used to increase the content of quinoline- and toluene-insoluble substances in pitches.

[0012] A known method for producing petroleum pitch, a composite material for the production of anode mass [RU No. 2722291, published 05 / 28 / 2020], includes the oxidation of petroleum residues, such as underoxidized petroleum bitumen (60-70% by weight) and heavy pyrolysis resin (10-20% by weight), mixing the petroleum residues with a fullerene-like carbon additive obtained as a by-product of silicon production, with a particle size of 1-10 nm in an amount of 20-30% by weight. The components are mixed at a temperature of 175-185°C.

[0013] A binder for the production of electrode materials, a method for its production and electrode materials are known [application for invention No. 2006131538, published 03 / 10 / 2008], in which 2.0-8.0% by weight of thermally expanded graphite is added to coal tar pitch with a softening temperature according to the “Ring and Ball” method >100°C, the components are mixed in a dry state, followed by heating the resulting mixture to 180-360°C and holding at the heating temperature.

[0014] Nanostructured coal tar pitch [RU No. 2394870, published 20.07.2010] is also known, obtained by mixing nanodispersed carbon [RU No. 2287543, published 20.11.2006] in an amount of 0.3-1.0 wt.% with coal tar pitch, heating the mixture above the softening temperature with constant stirring and cooling. Nanostructured coal tar pitch is used as a binder for the production of structural graphites.

[0015] The main disadvantage of modifying pitch with nano- and ultra-dispersed carbon additives is an increase in the softening temperature, which is undesirable for petroleum pitches.

[0016] A method for producing a sintering additive is known [application for invention RU No. 2004129618, published 03 / 27 / 2006] by oxidizing petroleum residues at a temperature of 230-250°C, characterized in that, in order to increase the sintering capacity of the additive, the petroleum residues are oxidized together with finely ground petroleum coke introduced into them in an amount of 5 to 35%.

[0017] The closest to the proposed invention in technical essence and the achieved result is the method of catalytic liquid-phase oxidative cracking of fuel oil [Doshlov I. O., Goryashin N. A., Kuzora I. E. Petroleum pitch from highly aromatic fuel oil / / Oil and Gas-2020. - 2020. - Pp. 166-174] using catalytically active complexing additives. According to the known technology, a special activating additive (up to 2%) was introduced into the petroleum feedstock (highly aromatic fuel oil), the mixture was placed in an autoclave, in which, at a temperature of 80 ° C and a pressure of 0.5 MPa and stirring, sequentially purging with water vapor and oxidation with air were carried out. Thermolysis was then carried out at temperatures ranging from 420-450°C, pressures ranging from 1-2 MPa, and a heat treatment time of 5-20 minutes during the dissolution stage. Phthalic anhydride, urotropine, benzoic acid, and heavy pyrolysis resin were used as modifying additives.The resulting petroleum pitch has a softening point of 88-91°C, a coke residue of at least 56.0%, a toluene-insoluble content of 36-38%, and a quinoline-insoluble content of 5-9% by weight. A disadvantage of the pitch composition and production method is the need for chemicals—catalytically active complexing additives—which are essential for producing petroleum pitches with properties similar to those of coal tar pitches. The pitch melt processing operations (steam blowing, oxidation) also require multiple stages and are time-consuming.

[0018] The technical result, which the group of inventions is aimed at achieving, consists in expanding the raw material base for the production of electrode pitches by processing petroleum residues and low-value coke breeze, as well as improving the quality of petroleum pitch in terms of a combination of softening temperature indicators, coke residue, and the content of substances insoluble in toluene and insoluble in quinoline.

[0019] An additional technical result is the production of a by-product - a suspension of coke breeze, which can be used as an oil sintering additive for the production of metallurgical coke or for anode mass.

[0020] The essence of the first invention from the group of inventions is as follows: petroleum pitch is obtained by thermal polycondensation, while petroleum coke is added to the highly aromatic petroleum residue, and the resulting mixture is processed at a temperature of 450-480 ° C for 1-2 hours, after the completion of the reaction, finely dispersed petroleum coke is removed.

[0021] The essence of the second invention from the group of inventions is as follows: petroleum pitch obtained by the proposed method in a mass ratio contains: petroleum coke: highly aromatic petroleum residue (1-5):(9-5).

[0022] When the mass ratio of petroleum coke: highly aromatic petroleum residue is less than 1:9, the requirements for the final product of electrode-grade petroleum pitch are not met; an increase in the mass ratio of petroleum coke: highly aromatic petroleum residue above 5:5 due to a decrease in the yield of the final product of petroleum pitch to values ​​below 50% by mass.

[0023] The highly aromatic petroleum residue may be selected from a group including heavy catalytic cracking gas oil, heavy pyrolysis resin, highly aromatic fuel oil with an initial boiling point of not lower than 300°C, a density of not lower than 1.0 g / cm 3 , coking capacity of at least 4%.

[0024] Petroleum coke (coke breeze) can be taken from delayed coking, fluidcoking, flexicoking units with a size of no more than 1.0 mm.

[0025] The technical characteristics of petroleum coke and highly aromatic petroleum residues are shown in Tables 1 and 2.

[0026]

[0027] Table 2

[0028] Origin Mass fraction of sulfur, % Volatile content, % Ash content, % Elemental composition, wt.% WITH N N S ABOUT Petroleum coke (coke breeze) No. 1 1,2 7,8 0,14 91,1 3,7 1,0 1,2 3,0 Petroleum coke (coke breeze) No. 2 2,2 9,1 0,6 90,0 4,2 0,8 2,2 2,8

[0029] Preferably, petroleum coke is removed by settling and / or filtration.

[0030] To obtain electrode-quality pitch (grades B1, B, B1), after removing coke, the resulting homogeneous product is thermally stabilized at 130-280°C to a constant weight, obtaining petroleum pitch as a residue.

[0031] The proposed method can be implemented both in periodic and continuous mode using standard equipment used in hydrocarbon raw material processing processes.

[0032] The present method for producing petroleum pitch was carried out as follows:

[0033] Stage 1 - crushing of petroleum coke and selection of fractions no more than 1 mm.

[0034] Stage 2 - Preparation of a mixture of crushed petroleum coke and highly aromatic petroleum residue. Pre-homogenized mixtures of petroleum coke and highly aromatic petroleum residue with a petroleum coke:highly aromatic petroleum residue weight ratio of (1-5):(9-5). For this, crushed and screened coke is mixed with a compounded solvent and homogenized using standard equipment.

[0035] Stage 3 - Thermal polycondensation of a mixture of petroleum coke and highly aromatic petroleum residue in a heated reactor equipped with a device for stirring the reaction mixture. The reactor is equipped with a steam-gas mixture collector, which is sent for separation. The process is carried out at a temperature of 450-480°C, a pressure no higher than 10.0 MPa, and a reaction time of 1.0-2.0 hours.

[0036] Stage 4 – Separation of the solid phase of the reaction products. The suspension obtained in stage 3 is discharged and subjected to settling or filtration at a temperature ensuring that the product remains in a liquid state of at least 80°C.

[0037] Settling is carried out in a heated settling tank for 1 hour, then the by-product lower phase of the coke suspension and the target upper phase of the homogeneous thermal polycondensation product are collected.

[0038] Filtration is performed in a heated, pressurized filter with a filter element with a pore size of no more than 0.2 mm. The target product, petroleum pitch, is collected from the filtrate collector.

[0039] By-product - coke breeze suspension, can be sent to granulation using standard equipment to obtain petroleum sintering additive for the production of metallurgical coke or for anode mass.

[0040] Stage 5 – thermal stabilization to produce electrode-grade petroleum pitch. The homogeneous thermal polycondensation product obtained in stage 4 is maintained at 130-280°C until constant weight is achieved to remove low-molecular hydrocarbon cracking products for 3-10 hours. The distilled light hydrocarbon fractions, after collection and condensation, can be used as a component of boiler fuels.

[0041] The obtained petroleum pitch was analyzed for the following parameters:

[0042] - softening temperature according to GOST 9950 (ring and rod method);

[0043] - coke residue according to GOST R ISO 6998-2017;

[0044] - content of substances insoluble in toluene according to GOST 7847;

[0045] - content of substances insoluble in quinoline according to GOST 10200 clause 4.4.1.2.;

[0046] - mass fraction of volatile substances according to GOST 9951.

[0047] The group of inventions is illustrated by the following examples.

[0048] Example 1: 50 g of crushed petroleum coke was separated using a sieve method to select a fraction of no more than 1 mm and mixed with 450 g of highly aromatic petroleum residue (heavy catalytic cracking gas oil, HCCO). The mass ratio of petroleum coke to highly aromatic petroleum residue is 1:9. The mixture was loaded into a batch autoclave reactor, heated to 400 °C with mechanical stirring, and thermal polycondensation of the mixture was carried out at this temperature, with stirring and at an autogenous pressure of no more than 10.0 MPa for 1 hour. The thermal polycondensation product was unloaded from the autoclave reactor and subjected to settling and / or filtration to separate the coke. Next, the homogeneous thermal polycondensation product was thermally stabilized at a temperature of 230°C to a constant weight to remove low-molecular hydrocarbon cracking products for at least 3 hours.

[0049] Example 2: The production of petroleum pitch was carried out similarly to Example 1, except for the temperature of the thermopolycondensation process (430°C).

[0050] Example 3: The production of petroleum pitch was carried out similarly to example 2, except for the temperature of the thermopolycondensation process (450°C).

[0051] Example 4: Petroleum pitch was produced in the same manner as Example 3, except for the duration of the thermal polycondensation process (1.5 hours). Thermal stabilization was carried out at 280°C.

[0052] Example 5: The production of petroleum pitch was carried out similarly to example 4, except for the temperature of the thermopolycondensation process (470°C).

[0053] Example 6: The production of petroleum pitch was carried out similarly to example 3, except for the temperature and duration of the thermopolycondensation process (480°C and 1.5 hours).

[0054] Example 7: The production of petroleum pitch was carried out similarly to example 6, except for the temperature of the thermal stabilization process

[0055] (130°C).

[0056] Example 8: The production of petroleum pitch was carried out similarly to Example 6, except for the temperature of the thermopolycondensation process.

[0057] (500°C).

[0058] Example 9: The production of petroleum pitch was carried out similarly to Example 6, except for the mass ratio of petroleum coke: highly aromatic petroleum residue of 2:8.

[0059] Example 10: The production of petroleum pitch was carried out similarly to example 6, except for the mass ratio of petroleum coke: highly aromatic petroleum residue of 3: 7. Before thermal stabilization, the resulting pitch had a softening temperature of 67°C, and a coke residue of 49%.

[0060] Example 11. Petroleum pitch was produced similarly to Example 6, except for the petroleum coke:highly aromatic petroleum residue weight ratio of 5:5 and the thermal polycondensation process duration (2 h). Before thermal stabilization, the resulting pitch had a softening point of 69°C and a coke residue of 50.5%. Thermal stabilization was performed at 180°C.

[0061] Example 12. The production of petroleum pitch was carried out similarly to Example 6, except that petroleum coke was not added to the highly aromatic petroleum residue.

[0062] Example 13. The production of petroleum pitch was carried out similarly to Example 6, except that heavy pyrolysis resin (HPR) was used as the highly aromatic petroleum residue.

[0063] Example 14. The production of petroleum pitch was carried out similarly to example 6, except that highly aromatic fuel oil (HAFO) was used as the highly aromatic petroleum residue and thermal stabilization was carried out at a temperature of 280°C.

[0064] The test data using the present method for producing petroleum pitch are shown in Table 3.

[0065] The result of examples 1-2 shows that the obtained samples of petroleum pitch do not meet the requirements for grades of electrode quality pitch according to GOST 10200 in terms of softening temperature (below plus 20°C with a requirement of at least 65°C), coke number (25.5 and 41.3, respectively, with a requirement of at least 49%) and the yield of volatile substances (81.3 and 72.6, respectively, with a requirement of no more than 63%).

[0066] The result of Example 8 shows that when the thermal polycondensation temperature increases to 500°C, rapid coking of the reaction mass occurs, thus petroleum pitch cannot be obtained.

[0067] The result of Example 12 shows that obtaining petroleum pitch of the required quality is possible only by using petroleum coke dust as an initiator of thermal polycondensation reactions.

[0068] The result of examples 3-7 and 10, 11 shows that the obtained samples meet the requirements of GOST 10200 for electrode pitch grades A, B1, B, B1, that is, from entirely petroleum raw materials (petroleum residues and petroleum coke), petroleum pitch samples were obtained with a softening point of at least 68°C with a coke residue of at least 49.2%, a content of substances insoluble in toluene of at least 24.1% and substances insoluble in quinoline of at least 7.2% and no more than 13.6%. The method makes it possible to expand the raw material base for the production of binder pitches for electrodes, and to ensure the processing of petroleum residues and low-value coke breeze.

[0069] The best results in achieving the requirements for electrode pitch grades B1 and V according to GOST 10200 are ensured at a thermal polycondensation temperature of at least 450°C and no more than 480°C and a thermal polycondensation duration of at least 1 hour (examples 3-6, 13, 14), while thermal stabilization can be carried out at temperatures of 230-280°C. Pitch samples meeting the requirements for grade A according to GOST 10200 were obtained without thermal stabilization (examples 10-11).

[0070] The minimum required mass ratio of petroleum coke: highly aromatic petroleum residue is 1:9, since when carrying out work under similar conditions with the addition of a minimum amount of petroleum coke (example 6) and without the addition of petroleum coke (example 12), samples of petroleum pitch were obtained that met the requirements of GOST 10200 and did not meet GOST 10200 for any of the determined indicators, respectively.

[0071] Table 3

[0072] Example Mass ratio Thermopolycondensation conditions Thermal stabilization temperature, °C Quality parameters of petroleum pitch petroleum coke highly aromatic petroleum residue T tk, °C τ tk, h Tp, °C K.O., % V, % α, % α1, % 1 1 (№1) 9 (THK) 400 1 230 below plus 20 25,5 81,3 21,2 5,6 2 1 (№1) 9 (THK) 430 1 230 below plus 20 41,3 72,6 24,8 6,9 3 1 (№1) 9 (THK) 450 1 230 71,2 55,0 54,2 39,5 10,1 4 1 (№1) 9 (THK) 450 1,5 280 91,3 56,4 53,2 38,6 11,3 5 1 (№2) 9 (THK) 470 1,5 280 95,1 62,0 50,6 49,8 12,8 6 1 (№1) 9 (THK) 480 1,5 230 76,3 57,2 52,4 42,6 12,6 7 1 (№1) 9 (THK) 480 1,5 130 68,1 49,2 62,4 24,1 7,2 8 1 (№1) 9 (THK) 500 1,5 230 solid product 96,8 16,9 81,8 78,7 9 2 (№1) 8 (THK) 480 1,5 230 68,3 52,1 61,7 36,7 9,6 10 3 (№1) 7 (THK) 480 1,5 230 101,2 64,7 52,1 42,4 10,3 11 5 (№1) 5 (THK) 480 2 180 96,8 58,1 50,6 39,5 12,9 12 - 10 (THK) 480 1,5 230 below plus 20 15,4 90,1 7,2 0 13 1 (№1) 9 (TSP) 480 1,5 230 88,6 59,4 51,1 33,5 7,2 14 1 (№2) 9 (VM) 480 1,5 280 99,4 56,2 52,0 41,4 13,6 Prototype - 420-450 0,1-0,3 - 88-91 56 55-57 36-38 5-9

[0073] Where:

[0074] T tk - thermopolycondensation temperature, °C

[0075] τ tk - duration of thermal polycondensation, h

[0076] T ts - thermal stabilization temperature, °C

[0077] τ ts - duration of thermal stabilization, h

[0078] Tp - softening temperature by the ring and rod method, °C

[0079] K.O. - coke residue, %;

[0080] V - yield of volatile substances, %

[0081] α - mass fraction of substances insoluble in toluene, %;

[0082] α1- mass fraction of substances insoluble in quinoline, %.

Claims

1. A method for producing petroleum pitch from highly aromatic petroleum residues by thermal polycondensation, wherein petroleum coke is added to the petroleum residue in a weight ratio of petroleum coke: highly aromatic petroleum residue (1-5):(9-5) and the resulting mixture is processed at a temperature of 450-480°C for 1-2 hours, after completion of the reaction the finely dispersed petroleum coke is removed.

2. The method according to paragraph 1, characterized in that petroleum coke is removed by settling and / or filtration.

3. The method for producing petroleum pitch according to paragraph 1, characterized in that after removing the coke, the resulting homogeneous product is thermally stabilized at 130-280°C to a constant weight, obtaining petroleum pitch as a residue.

4. Petroleum pitch obtained by the method according to paragraph 1, with a mass ratio of petroleum coke: highly aromatic petroleum residue (1-5):(9-5).

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