Process for the denitrification of oils by extraction and its applications, denitrified oils obtained by this process and their applications

Abstract

The present application relates to the technical field of petroleum chemical industry, in particular to a method for denitrogenation by extraction and application thereof, and denitrogenated oil prepared by the method and application thereof. The method comprises the following steps: (1) inter-solubilizing nitrogen-containing heavy oil and polar solvent to obtain a mixed liquid; (2) repeatedly extracting the mixed liquid with non-polar solvent for multiple times, mixing the obtained multiple extraction phases, and recovering the first solvent to obtain a first recovery liquid and denitrogenated oil. The method provided by the present application realizes effective removal of nitrogen-containing compounds in the nitrogen-containing heavy oil, especially effective removal of non-basic nitrogen-containing compounds, and at the same time, avoids large loss of aromatic components in the nitrogen-containing heavy oil.

Description

Technical Field

[0001] This invention relates to the field of petrochemical technology, specifically to an extraction denitrification method and its application, and a denitrified oil obtained by the method and its application. Background Technology

[0002] Catalytic cracking technology is a key technology for the secondary processing of crude oil in refineries. However, with the increasing severity and depth of crude oil processing, the production of catalytic cracking slurry oil is gradually increasing, and the content of metals, gums, and non-hydrocarbon compounds is also increasing. Currently, catalytic cracking slurry oil is mainly used as a blending component for fuel oil, resulting in low product utilization value and significant greenhouse gas emissions after combustion. Catalytic cracking slurry oil is rich in short-chain polycyclic aromatic hydrocarbons and is a high-quality feedstock for the production of needle coke. Currently, the process for producing needle coke using catalytic cracking slurry oil in China is relatively mature, and there are already industrial application examples. Needle coke for graphite electrodes is a high-end carbon material and can be used as a high-power and ultra-power graphite electrode. The product standard T / ZGTS 022-2019 sets high requirements for nitrogen content, with the premium grade requiring a nitrogen content of no more than 0.1 wt%. The nitrogen content in catalytic cracking slurry oil is typically between 0.1-0.5 wt%, far exceeding this limit, and is mainly composed of non-alkaline nitrogen compounds. Therefore, an effective denitrification process is needed to remove 35%-80% of the non-alkaline nitrogen, which will meet the requirements of needle coke for low-nitrogen catalytic slurry.

[0003] For catalytic cracking slurry oil used in heavy distillate production, denitrification methods mainly include hydrorefining and non-hydrorefining methods. Hydrorefining can remove metals, olefins, sulfur oxides, and some nitrogen compounds from the oil, but it involves high investment and production costs, and has a poor removal rate for non-basic nitrogen. Non-hydrorefining methods include adsorption, acid-base neutralization, solvent extraction, and complexation denitrification. Currently available non-hydrorefining methods primarily target the removal of basic nitrogen, relying on the basic sites of basic nitrogen to achieve nitrogen removal through acid-base interactions or adsorption.

[0004] CN108239556A discloses the use of formic acid solvent and titanium tetrachloride complexing agent to separate basic and non-basic nitrogen compounds, achieving high-purity purification of both types of nitrogen compounds, but the process is complex. This solvent extraction method utilizes the difference in solubility between nitrogen compounds and hydrocarbon components in the feed oil to achieve denitrification. However, because nitrogen compounds and hydrocarbon components, especially aromatic components, have similar polarities, aromatics are also removed during denitrification, resulting in a low denitrification rate and low refined oil yield.

[0005] CN103215067A discloses a method for refining coking wax oil using a mixed solvent of furfural and organic acids, achieving a total nitrogen removal rate of up to 80%, but also removing a large amount of aromatic components, reducing the aromatic content by more than 60%.

[0006] Nitrogen-containing compounds in heavy petroleum products are mainly aromatic quinolines and their homologues, pyridines and their homologues, carbazoles and their homologues, indole and their homologues, etc. Due to the presence of nitrogen atoms, these nitrogen-containing compounds have relatively high solubility parameters compared to hydrocarbon components in petroleum. They also exhibit strong molecular polarity, and polar solvents provide better solubility for them. For example, the solubility parameter of basic nitrogen-containing quinolines is 23.13 (J·cm⁻¹). -3 The solubility parameter for non-basic nitrogen indole is 24.73 (J·cm⁻¹). -3 Catalytic cracking slurry contains high levels of aromatics, primarily polycyclic aromatic hydrocarbons (PAHs) such as tricyclic and tetracyclic rings. Despite the presence of π bonds and their relatively strong molecular polarity, the solubility parameters of PAHs are still lower than those of nitrogen-containing compounds; for example, the solubility parameter of anthracene is 21.7 (J·cm⁻¹). -3 The solubility parameters of these compounds differ somewhat from those of nitrogen-containing compounds. Furthermore, catalytic cracking slurry oil has a high viscosity, making it difficult to disperse and mix with denitrifying agents at lower temperatures. Solvent extraction methods can effectively remove nitrogen-containing compounds from the slurry oil by utilizing polarity differences, especially highly polar non-basic nitrogen compounds. However, this also removes a large amount of polar compounds such as aromatics, resulting in significant aromatic loss, poor extraction selectivity, and hindering subsequent carbon material production and processing.

[0007] Therefore, there is an urgent need for an extraction denitrification method based on nitrogen-containing heavy oil, especially an extraction denitrification method based on catalytic cracking slurry. Summary of the Invention

[0008] The purpose of this invention is to overcome the problems of high aromatic loss, poor selectivity, and low denitrification oil yield when using existing solvent extraction processes to remove nitrogen compounds (especially non-basic nitrogen compounds) from nitrogen-containing heavy oil (especially catalytic cracking slurry). This invention provides an extraction denitrification method and its application, a denitrified oil obtained by the method and its application. This method can remove nitrogen compounds, especially non-basic nitrogen compounds, from nitrogen-containing heavy oil with high selectivity while ensuring a high yield of denitrified oil.

[0009] To achieve the above objectives, the first aspect of the present invention provides a method for extraction denitrification, the method comprising the following steps:

[0010] (1) Mix nitrogen-containing heavy oil and polar solvent to obtain a mixture;

[0011] (2) The mixture is repeatedly extracted with a non-polar solvent, and the resulting multiple extract phases are mixed and the first solvent is recovered to obtain the first recovered liquid and denitrified oil.

[0012] Preferably, the process of repeated extraction includes:

[0013] i. The mixture is subjected to a first extraction with the non-polar solvent to obtain an extract phase of denitrified liquid 1 and a raffinate phase of nitrogen-containing liquid 1;

[0014] ii. The nitrogen-containing liquid 1 is subjected to a second extraction with the non-polar solvent to obtain the extract phase as denitrified liquid 2 and the raffinate phase as nitrogen-containing liquid 2;

[0015] iii. The nitrogen-containing liquid m-1 is extracted with the non-polar solvent to obtain the extract phase as denitrified liquid m and the raffinate phase as nitrogen-containing liquid m;

[0016] Where m is a positive integer and m≥3.

[0017] The second aspect of this invention provides an application of the method provided in the first aspect in the denitrification of nitrogen-containing heavy oil.

[0018] The third aspect of the present invention provides a denitrified oil obtained by the method provided in the first aspect.

[0019] The fourth aspect of this invention provides the application of the denitrification oil provided in the third aspect in the production and processing of carbon materials.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] (1) The extraction denitrification method provided by the present invention uses nitrogen-containing heavy oil as raw material, especially catalytic cracking slurry as raw material. Under the premise of mutual solubility between the raw material and the polar solvent, the non-polar solvent is used for multiple extractions, so that the non-nitrogen-containing components in the raw material are extracted into the non-polar solvent, while the nitrogen-containing components are retained in the polar solvent. This achieves the effective removal of nitrogen-containing compounds in nitrogen-containing heavy oil, especially the effective removal of non-alkaline nitrogen-containing compounds. At the same time, it improves the yield of denitrified oil and avoids a large loss of aromatic components in nitrogen-containing heavy oil.

[0022] (2) The method provided by the present invention uses conventional organic solvents, that is, polar and non-polar solvents are widely available; the process flow of this method is simple and easy to industrialize.

[0023] (3) The denitrified oil obtained by the method provided by the present invention has a high yield and denitrification efficiency, as well as a low aromatic loss rate. It can be used as a high-quality raw material for subsequent carbon material production and processing, especially as a raw material for needle coke production and processing. Detailed Implementation

[0024] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0025] In this invention, unless otherwise specified, the terms "first" and "second" do not indicate a sequence or limit the specific materials or steps; they are merely used to distinguish between different materials or steps. For example, "first solvent recovery" and "second solvent recovery" are simply used to distinguish that they are not the same solvent recovery.

[0026] The first aspect of this invention provides a method for extraction and denitrification, the method comprising the following steps:

[0027] (1) Mix nitrogen-containing heavy oil and polar solvent to obtain a mixture;

[0028] (2) The mixture is repeatedly extracted with a non-polar solvent, and the resulting multiple extract phases are mixed and the first solvent is recovered to obtain the first recovered liquid and denitrified oil.

[0029] The inventors of this invention have discovered that by utilizing a high-temperature, multiple-stage reverse extraction process—that is, first heating nitrogen-containing heavy oil and a polar solvent until they are miscible, and then performing multiple reverse extractions with a non-polar solvent—highly selective removal of nitrogen compounds, especially non-basic nitrogen compounds, from nitrogen-containing heavy oil is achieved. This process also increases the yield of the denitrified oil and avoids the reduction of aromatic components. Furthermore, the denitrified oil obtained using the method provided by this invention exhibits low nitrogen and high aromatic content, making it suitable as a raw material for the production and processing of carbon materials.

[0030] In some embodiments of the present invention, preferably, the density of the nitrogen-containing heavy oil is 800-1200 kg / m³. 3 The preferred value is 950-1100 kg / m³. 3 The kinematic viscosity at 100℃ is 8-30 mm. 2 / s, preferably 10-15mm 2 / s; nitrogen content is 0.01-5wt%, preferably 0.1-1wt%; basic nitrogen content is 1-1000mg / kg, preferably 10-500mg / kg; aromatic content is 20-99wt%, preferably 50-90wt%.

[0031] In this invention, unless otherwise specified, the density parameter is measured using GB / T 13377 (Determination of density or relative density of crude oil and liquid or solid petroleum products); the kinematic viscosity parameter is measured using GB / T 265 (Determination of kinematic viscosity and calculation of dynamic viscosity of petroleum products); the nitrogen content parameter is measured using SH / T 0704 (Determination of nitrogen content in petroleum and petroleum products by boat-injection chemiluminescence); and the alkaline nitrogen content parameter is measured using SH / T 0162 (Determination of alkaline nitrogen in petroleum products).

[0032] In this invention, a wide range of types of nitrogen-containing heavy oil can be selected, as long as the physical properties of the nitrogen-containing heavy oil meet the above-mentioned limitations. Preferably, the nitrogen-containing heavy oil is selected from at least one of catalytic cracking slurry oil, vacuum distillate oil, vacuum residue oil, and coking wax oil, and is more preferably catalytic cracking slurry oil.

[0033] In this invention, the polar solvent can form a strong interaction with nitrogen-containing compounds, especially non-basic nitrides, in the nitrogen-containing heavy oil, thereby preventing nitrogen-containing compounds from entering the non-polar solvent during the extraction process.

[0034] In some embodiments of the present invention, preferably, the solubility parameter of the polar solvent is >22 (J·cm). -3 ) 0.5 Preferably 24-28 (J·cm) -3 ) 0.5 In this invention, unless otherwise specified, the solubility parameters are obtained from a solubility parameter handbook.

[0035] In some embodiments of the present invention, preferably, the polar solvent comprises a main solvent and an optional secondary solvent; more preferably, the main solvent content in the polar solvent is 90-100 wt%, preferably 90-99.9 wt%, more preferably 95-99.5 wt%; and the secondary solvent content is 0-10 wt%, preferably 0.1-10 wt%, more preferably 0.5-5 wt%.

[0036] In some embodiments of the present invention, preferably, the main solvent is selected from at least one of dimethyl sulfoxide, sulfolane, furfural, phenol, N-methylpyrrolidone and N,N-dimethylformamide, and more preferably dimethyl sulfoxide and / or sulfolane.

[0037] In some embodiments of the present invention, preferably, the secondary solvent is selected from at least one of water, C1-C5 alcohols and benzaldehyde, more preferably water and / or C1-C5 alcohols; more preferably, the C1-C5 alcohols are selected from at least one of methanol, ethanol, ethylene glycol, glycerol and butanol, more preferably ethanol.

[0038] In a preferred embodiment of the present invention, the polar solvent comprises a primary solvent and a secondary solvent, wherein the primary solvent is dimethyl sulfoxide and / or sulfolane, and the secondary solvent is water and / or ethanol; the primary solvent content in the polar solvent is 90-100 wt%, preferably 90-99.9 wt%, more preferably 95-99.5 wt%; and the secondary solvent content is 0-10 wt%, preferably 0.1-10 wt%, more preferably 0.5-5 wt%.

[0039] In this invention, in step (1), the miscibility temperature is the temperature at which nitrogen-containing heavy oil and polar solvent mix and settle without stratification. That is, at the miscibility temperature, the nitrogen-containing heavy oil has good fluidity and can be mixed uniformly with the polar solvent, and all nitrogen-containing compounds in the nitrogen-containing heavy oil can dissolve in the polar solvent. Preferably, the miscibility temperature is 80-200℃, for example, 80℃, 100℃, 120℃, 150℃, 160℃, 180℃, 200℃, and any value within any range of any two values, preferably 120-160℃.

[0040] In some embodiments of the present invention, preferably, the weight ratio of the nitrogen-containing heavy oil to the polar solvent is 1:0.1-5, for example, 1:0.1, 1:0.2, 1:0.3, 1:0.5, 1:0.8, 1:1, 1:2, 1:3, 1:4, 1:5, and any value within any range of two such values, preferably 1:0.3-1. When the weight ratio of the nitrogen-containing heavy oil to the polar solvent is too high, i.e., the amount of polar solvent used is low, the denitrification effect is poor; when the weight ratio of the nitrogen-containing heavy oil to the polar solvent is too low, i.e., the amount of polar solvent used is high, the denitrification effect is obvious, but the loss of aromatics is greater.

[0041] In this invention, since the miscibility temperature of nitrogen-containing heavy oil and polar solvent is relatively high, in order to avoid the volatilization of non-polar solvent, the non-polar solvent is generally an alkane reagent with a suitable number of carbon atoms. In addition, the alkane reagent has low polarity and good solubility with the aromatic components in nitrogen-containing heavy oil. It has poor selectivity for the extraction of nitrogen-containing compounds in polar solvent, and can back-extract the aromatic components in nitrogen-containing heavy oil into the alkane reagent, thus avoiding the back-extraction of too many nitrogen-containing compounds.

[0042] In some embodiments of the present invention, preferably, the nonpolar solvent is a saturated alkane, preferably selected from C6-C6. 20 n-Alkanes, C6-C 20 Isomers of alkanes and C6-C 20 At least one of the cycloalkanes, more preferably C8-C 16 n-Alkanes, such as n-octane, n-decane, n-dodecane, etc.

[0043] In some embodiments of the present invention, preferably, the weight ratio of nitrogen-containing heavy oil and non-polar solvent in the mixture is 1:0.05-2, for example, 1:0.05, 1:0.1, 1:0.15, 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:1, 1:2, and any value within any range of two such values, preferably 1:0.15-0.5. When the weight ratio of nitrogen-containing heavy oil and non-polar solvent is too high, i.e., the amount of non-polar solvent is low, the back-extraction effect is poor, and the product yield is low; when the weight ratio of nitrogen-containing heavy oil and non-polar solvent is too low, i.e., the amount of non-polar solvent is high, the back-extraction effect is good, but at the same time, nitrogen-containing compounds will be back-extracted, resulting in a low denitrification rate.

[0044] In some embodiments of the present invention, preferably, the temperature of the repeated extraction is 80-200°C, for example, 80°C, 100°C, 120°C, 150°C, 160°C, 180°C, 200°C, or any value within a range of any two values, preferably 120-160°C; more preferably, the temperature of the repeated extraction is the same as the temperature at which the components are miscible. This arrangement facilitates the back-extraction of non-nitrogenous components in the mixture into a non-polar solvent phase, while retaining nitrogenous components in a polar solvent, thereby effectively separating nitrogenous and non-nitrogenous components from nitrogenous heavy oil.

[0045] In this invention, the process of repeated extraction has a wide range of options. For example, Method 1: The mixture is divided into multiple streams and extracted sequentially with the non-polar solvent. The resulting extract phase is a denitrified liquid (i.e., a non-polar solvent containing non-nitrogenous components), and the raffinate phase is a nitrogen-containing liquid (i.e., a polar solvent containing nitrogenous components). Method 2: The mixture is extracted with the non-polar solvent. The resulting extract phase is a denitrified liquid 1, and the raffinate phase is a nitrogen-containing liquid 1. The nitrogen-containing liquid 1 is then extracted with the non-polar solvent. The resulting extract phase is a denitrified liquid 2, and the raffinate phase is a nitrogen-containing liquid 2. The nitrogen-containing liquid 2 is then extracted with the non-polar solvent. The resulting extract phase is a denitrified liquid 3, and the raffinate phase is a nitrogen-containing liquid 3, and so on, until the resulting extract phase is a denitrified liquid m, and the raffinate phase is a nitrogen-containing liquid m. Compared to Method 1, Method 2 can avoid the loss of aromatic components in nitrogen-containing heavy oil by back-extracting the aromatic components into the non-polar solvent.

[0046] In some embodiments of the present invention, preferably, the multiple repeated extraction process includes: i) performing a first extraction on the mixture using the non-polar solvent to obtain an extract phase of denitrified liquid 1 and a raffinate phase of nitrogen-containing liquid 1; ii) performing a second extraction on the nitrogen-containing liquid 1 using the non-polar solvent to obtain an extract phase of denitrified liquid 2 and a raffinate phase of nitrogen-containing liquid 2; iii) performing a m-th extraction on the nitrogen-containing liquid m-1 using the non-polar solvent to obtain an extract phase of denitrified liquid m and a raffinate phase of nitrogen-containing liquid m; wherein m is a positive integer and m≥3. In the present invention, using multiple repeated extractions is more beneficial to improving the yield of denitrified oil.

[0047] In some embodiments of the present invention, preferably, the amount of non-polar solvent added is the same or different during the first extraction, the second extraction, ..., the mth extraction, and preferably the same.

[0048] In this invention, unless otherwise specified, nitrogen-containing liquid 1, nitrogen-containing liquid 2, ..., nitrogen-containing liquid m are each independently a polar solvent rich in nitrogen components; denitrification liquid 1, denitrification liquid 2, ..., denitrification liquid m are each independently a nonpolar solvent without nitrogen components.

[0049] In this invention, the first solvent recovery aims to recover non-polar solvents from multiple extraction phases (i.e., denitrification liquid 1, denitrification liquid 2, ... and denitrification liquid m) to obtain a first recovered liquid and denitrified oil. In this invention, the conditions for the first solvent recovery depend on the boiling point of the non-polar solvent. Preferably, in step (2), the conditions for the first solvent recovery include: a temperature of 150-250°C and a time of 90-300 min.

[0050] According to the present invention, preferably, the method further includes: returning the first recovered liquid as a circulating nonpolar solvent and mixing it into the nonpolar solvent.

[0051] According to the present invention, preferably, the method further includes: mixing the nitrogen-containing liquid 1, nitrogen-containing liquid 2, ... and nitrogen-containing liquid m and then performing a second solvent recovery to obtain a second recovered liquid and nitrogen-containing oil.

[0052] In this invention, the second solvent recovery aims to recover polar solvents from multiple raffinate phases (i.e., nitrogen-containing liquid 1, nitrogen-containing liquid 2, ... and nitrogen-containing liquid m) to obtain a second recovered liquid and nitrogen-containing oil. In this invention, the second solvent recovery depends on the boiling point of the polar solvent. Preferably, the conditions for the second solvent recovery include a temperature of 150-250°C and a time of 90-300 min.

[0053] In some embodiments of the present invention, preferably, the method further includes: returning the second recovered liquid as a circulating polar solvent and mixing it into the polar solvent.

[0054] According to a particularly preferred embodiment of the present invention, the method includes the following steps:

[0055] (1) Mix nitrogen-containing heavy oil and polar solvent to obtain a mixture;

[0056] (2) The mixture is repeatedly extracted with a non-polar solvent, and the resulting multiple extract phases are mixed and then subjected to a first solvent recovery to obtain a first recovered liquid and denitrified oil; and the resulting multiple raffinate phases are mixed and then subjected to a second solvent recovery to obtain a second recovered liquid and nitrogen-containing oil;

[0057] The weight ratio of nitrogen-containing heavy oil and non-polar solvent in the mixture is 1:0.05-2;

[0058] The multiple repeated extraction processes include: i. performing a first extraction on the mixture using the non-polar solvent to obtain an extract phase of denitrified liquid 1 and a raffinate phase of nitrogen-containing liquid 1; ii. performing a second extraction on the nitrogen-containing liquid 1 using the non-polar solvent to obtain an extract phase of denitrified liquid 2 and a raffinate phase of nitrogen-containing liquid 2; iii. performing a m-th extraction on the nitrogen-containing liquid m-1 using the non-polar solvent to obtain an extract phase of denitrified liquid m and a raffinate phase of nitrogen-containing liquid m; wherein m is a positive integer and m≥3;

[0059] The temperature at which the extraction is repeated multiple times is the same as the temperature at which the substances are miscible.

[0060] The second aspect of this invention provides an application of the method provided in the first aspect in the denitrification of nitrogen-containing heavy oil.

[0061] The method described above is used for denitrification of nitrogen-containing heavy oil, especially for denitrification of catalytic cracking slurry. It ensures the effective removal of nitrogen-containing compounds, especially non-alkaline nitrogen-containing compounds, from the catalytic cracking slurry while avoiding the loss of aromatic components in the catalytic cracking slurry.

[0062] The third aspect of the present invention provides a denitrified oil obtained by the method provided in the first aspect.

[0063] According to the present invention, preferably, the nitrogen content in the denitrified oil is 0.01-1 wt%, more preferably 0.05-0.2 wt%.

[0064] The fourth aspect of this invention provides the application of the denitrification oil provided in the third aspect in the production and processing of carbon materials.

[0065] The denitrified oil obtained by the method provided by this invention has the characteristics of low nitrogen and high aromatics, and can be used for the production and processing of carbon materials, especially for the production and processing of needle coke.

[0066] The present invention will be described in detail below through embodiments.

[0067]

[0068]

[0069] Among them, the non-alkaline nitrogen content in nitrogen-containing heavy oil = nitrogen content in nitrogen-containing heavy oil - alkaline nitrogen content in nitrogen-containing heavy oil; the non-alkaline nitrogen content in denitrified oil = nitrogen content in denitrified oil - alkaline nitrogen content in denitrified oil.

[0070] The density parameter was measured in accordance with GB / T 13377 (Determination of density or relative density of crude oil and liquid or solid petroleum products);

[0071] The kinematic viscosity parameters were measured using GB / T 265 (Determination of kinematic viscosity and calculation of dynamic viscosity of petroleum products);

[0072] The nitrogen content parameter was determined using SH / T 0704 (Determination of nitrogen content in petroleum and petroleum products by boat-injection chemiluminescence method);

[0073] The alkaline nitrogen content parameter was determined using SH / T 0162 (Determination of alkaline nitrogen in petroleum products).

[0074] Catalytic cracking slurry oil-I and catalytic cracking slurry oil-II are both from a refinery of Sinopec. Their specific compositions and nitrogen contents are listed in Table 1.

[0075] Table 1

[0076]

[0077]

[0078] Note: *Measured using SH / T 0659 (Determination of hydrocarbons in saturated hydrocarbon fractions of gas oil).

[0079] Example 1

[0080] (1) Add 300g of catalytic cracking slurry-I and dimethyl sulfoxide (solubility parameter is 26.7 (J·cm⁻¹) to the solution. -3 ) 0.5 The mixtures are mixed and heated until they are miscible to obtain a mixture; wherein the weight ratio of catalytic cracking slurry-I and dimethyl sulfoxide is 1:0.5, and the miscibility temperature is 129℃.

[0081] (2) At the above temperature, the catalytic cracking slurry-I and n-decane in the above mixture are extracted at a weight ratio of 1:0.2, and the amount of n-decane is 60g. The extract phase is denitrification liquid 1 and the raffinate phase is nitrogen-containing liquid 1.

[0082] (3) Mix the above nitrogen-containing liquid 1 with 60g of n-decane and repeat step (2) to obtain denitrified liquid 2 and nitrogen-containing liquid 2; mix the above nitrogen-containing liquid 2 with 60g of n-decane and repeat step (2) to obtain denitrified liquid 3 and nitrogen-containing liquid 3.

[0083] (4) After mixing the above denitrification liquid 1, denitrification liquid 2 and denitrification liquid 3, the first solvent is recovered (temperature is 175℃, time is 120min) to obtain the first recovered liquid and denitrification oil S1. The first recovered liquid is returned as a circulating non-polar solvent and mixed into the non-polar solvent (n-decane). The physical property parameters of denitrification oil S1 are listed in Table 2.

[0084] Example 2

[0085] (1) Mix 300g of catalytic cracking slurry-I with a mixed polar solvent (solubility parameter is 27.1 (J·cm⁻¹)). -3 ) 0.5 The mixed polar solvent consists of 99 wt% dimethyl sulfoxide and 1 wt% water, wherein the solubility parameter of dimethyl sulfoxide is 26.7 (J·cm⁻¹). -3 ) 0.5 The water solubility parameter is 47.8 (J·cm⁻¹). -3 ) 0.5 The mixtures are mixed and heated until they are miscible to obtain a mixture; wherein the weight ratio of catalytic cracking slurry-I and dimethyl sulfoxide is 1:0.3, and the miscibility temperature is 136℃.

[0086] (2) At the above temperature, the catalytic cracking slurry-I and n-dodecane in the above mixture are extracted and separated by sedimentation at a weight ratio of 1:0.15. The amount of n-dodecane is 45g. The extract phase is denitrified liquid 1 and the raffinate phase is nitrogen-containing liquid 1.

[0087] (3) Mix the above nitrogen-containing liquid 1 with 45g of n-dodecane and repeat step (2) to obtain denitrified liquid 2 and nitrogen-containing liquid 2; mix the above nitrogen-containing liquid 2 with 45g of n-dodecane and repeat step (2) to obtain denitrified liquid 3 and nitrogen-containing liquid 3;

[0088] (4) After mixing the above denitrification liquid 1, denitrification liquid 2 and denitrification liquid 3, the first solvent is recovered (temperature is 215℃, time is 150min) to obtain the first recovered liquid and denitrification oil S2. The first recovered liquid is returned as a circulating non-polar solvent and mixed into the non-polar solvent (n-dodecane). The physical property parameters of denitrification oil S2 are listed in Table 2.

[0089] Example 3

[0090] (1) Add 300g of catalytic cracking slurry-II and dimethyl sulfoxide (solubility parameter is 26.7 (J·cm⁻¹) to the mixture. -3 ) 0.5The mixtures are mixed and heated until they are miscible to obtain a mixture; wherein the weight ratio of catalytic cracking slurry-I and dimethyl sulfoxide is 1:1, and the miscibility temperature is 131℃.

[0091] (2) At the above temperature, the catalytic cracking slurry-II and n-dodecane in the above mixture are extracted and separated by sedimentation at a weight ratio of 1:0.5. The amount of n-dodecane is 150g, and the extract phase is denitrification liquid 1 and the raffinate phase is nitrogen-containing liquid 1.

[0092] (3) Mix the above nitrogen-containing liquid 1 with 150g of n-dodecane and repeat step (2) to obtain denitrified liquid 2 and nitrogen-containing liquid 2; mix the above nitrogen-containing liquid 2 with 150g of n-dodecane and repeat step (2) to obtain denitrified liquid 3 and nitrogen-containing liquid 3;

[0093] (4) After mixing the above denitrification liquid 1, denitrification liquid 2 and denitrification liquid 3, the first solvent is recovered (temperature is 215℃, time is 150min) to obtain the first recovered liquid and denitrification oil S3. The first recovered liquid is returned as a circulating non-polar solvent and mixed into the non-polar solvent (n-dodecane). The physical property parameters of denitrification oil S3 are listed in Table 2.

[0094] Example 4

[0095] The method of Example 1 is followed, except that in step (1), the weight ratio of catalytic cracking slurry-I and dimethyl sulfoxide is replaced with 1:0.1, and the other steps are the same to obtain denitrified oil S4. The physical properties of denitrified oil S4 are listed in Table 2.

[0096] Example 5

[0097] The method of Example 1 is followed, except that in step (2), the weight ratio of catalytic cracking slurry-I and n-decane in the above mixture is replaced with 1:0.05, and the other steps are the same to obtain denitrified oil S5. The physical properties of denitrified oil S5 are listed in Table 2.

[0098] Comparative Example 1

[0099] The method of Example 1 is different except that step (3) is omitted. The denitrification liquid 1 obtained in step (2) is directly subjected to the first solvent recovery. The remaining steps are the same to obtain denitrification oil DS1. The physical properties of denitrification oil DS1 are listed in Table 2.

[0100] Comparative Example 2

[0101] The method of Example 1 is the same except that in step (1), the temperature at which the oil is miscible is replaced with 50°C and n-decane is added at this temperature. That is, catalytic cracking slurry-I and dimethyl sulfoxide are immiscible. The remaining steps are the same to obtain denitrogenated oil DS2. The physical properties of denitrogenated oil DS2 are listed in Table 2.

[0102] Comparative Example 3

[0103] 300g of catalytic cracking slurry-II and 450g of furfural were extracted to obtain a nitrogen-containing extract and a denitrified extract. The denitrified extract was then subjected to solvent removal treatment at 80℃ to obtain denitrified oil DS3. The physical properties of denitrified oil DS3 are listed in Table 2.

[0104] Table 2

[0105] Example 1 Example 2 Example 3 Example 4 Yield / % 91.2 88.5 93.1 96.4 <![CDATA[Density (20 °C) / kg / m 3 > 1016.1 1013.4 1079.4 1021.2 Aromatic content / wt% 64.3 63.7 65.1 65.7 Nitrogen content / wt% 0.12 0.09 0.045 0.19 alkaline nitrogen / mg / kg 115 105 50 119 Total nitrogen removal rate / % 55.5 66.7 62.5 29.6 Denitrification rate of non-alkaline nitrogen / % 57.8 69.1 69.9 30.8

[0106] Continued from Table 2

[0107] Example 5 Comparative Example 1 Comparative Example 2 Comparative Example 3 Yield / % 61.3 41.3 86.7 22.1 <![CDATA[Density (20 °C) / kg / m 3 > 1002.1 993.7 1029.3 987.1 Aromatic content / wt% 58.7 51.2 64.9 48.2 Nitrogen content / wt% 0.10 0.13 0.18 0.1 alkaline nitrogen / mg / kg 106 99 115 76 Total nitrogen removal rate / % 62.9 51.9 33.3 62.9 Denitrification rate of non-alkaline nitrogen / % 65.3 53.3 34.5 64.1

[0108] As shown in Table 2, compared with the comparative example, the denitrified oil prepared by the method provided by this invention has both a higher denitrification rate and yield of non-alkaline nitrogen and less aromatic loss. In particular, at the miscible temperature, through multiple reverse repeated extractions, the aromatic components in the catalytic cracking slurry can be back-extracted into the denitrification liquid, while the nitrogen-containing compounds are retained in the nitrogen-containing liquid, further realizing the effective removal of nitrogen compounds, especially non-alkaline nitrogen-containing compounds, from the catalytic cracking slurry with less aromatic loss.

[0109] Specifically, in Examples 2 and 3, the nitrogen content in the denitrified oil is less than 0.1 wt%, which can be used as a high-quality raw material for producing premium graphite electrodes. In Comparative Example 1, when only one back-extraction is used, although the denitrification rate is high, the yield of denitrified oil is low and the loss of aromatics is large. In Comparative Example 2, when back-extraction is performed at low temperature, although the loss rate of aromatics is low, the denitrification effect is not ideal, and the total denitrification rate is only 33.3%. In Comparative Example 3, conventional extraction is used, which has a high denitrification rate, but the yield of denitrified oil is low and the loss of aromatics is large.

[0110] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for extraction and denitrification, characterized in that, The method includes the following steps: (1) Nitrogen-containing heavy oil and a polar solvent are mixed at 80-200℃ to obtain a mixture; wherein the solubility parameter of the polar solvent is >22 (J·cm). -3 ) 0.5 The solvent comprises a main solvent and an optional secondary solvent; wherein the main solvent is selected from at least one of dimethyl sulfoxide, sulfolane, furfural, phenol, N-methylpyrrolidone, and N,N-dimethylformamide; and the secondary solvent is selected from at least one of water, C1-C5 alcohols, and benzaldehyde. (2) The mixture is repeatedly extracted with a non-polar solvent at 80-200°C, and the resulting multiple extract phases are mixed and subjected to first solvent recovery to obtain a first recovered liquid and denitrified oil; wherein the non-polar solvent is C6-C. 20 n-Alkanes, C6-C 20 Isomers of alkanes and C6-C 20 At least one of the cycloalkanes; the weight ratio of nitrogen-containing heavy oil and non-polar solvent in the mixture is 1:0.05-2.

2. The method according to claim 1, wherein, The density of the nitrogen-containing heavy oil is 800-1200 kg / m³. 3 The kinematic viscosity at 100℃ is 8-30 mm. 2 / s; nitrogen content is 0.01-5wt%; basic nitrogen content is 1-1000 mg / kg; aromatic content is 20-99wt%.

3. The method according to claim 2, wherein, The density of the nitrogen-containing heavy oil is 950-1100 kg / m³. 3 The kinematic viscosity at 100℃ is 10-15 mm. 2 / s; nitrogen content is 0.1-1wt%; basic nitrogen content is 10-500 mg / kg; aromatic content is 50-90wt%.

4. The method according to claim 1, wherein, The nitrogen-containing heavy oil is selected from at least one of catalytic cracking slurry oil, vacuum distillate oil, vacuum residue oil, and coking wax oil.

5. The method according to claim 4, wherein, The nitrogen-containing heavy oil is catalytic cracking slurry.

6. The method according to claim 1, wherein, The solubility parameter of the polar solvent is 24-28 (J·cm⁻¹). -3 ) 0.5 .

7. The method according to claim 1, wherein, The polar solvent contains 90-100 wt% of the primary solvent and 0-10 wt% of the secondary solvent.

8. The method according to claim 7, wherein, The polar solvent contains 90-99.9 wt% of the primary solvent and 0.1-10 wt% of the secondary solvent.

9. The method according to claim 8, wherein, The polar solvent contains 95-99.5 wt% of the main solvent and 0.5-5 wt% of the secondary solvent.

10. The method according to claim 1, wherein, The main solvent is dimethyl sulfoxide and / or sulfolane.

11. The method according to claim 1, wherein, The secondary solvent in the polar solvent is water and / or a C1-C5 alcohol.

12. The method according to claim 11, wherein, The C1-C5 alcohols are selected from at least one of methanol, ethanol, ethylene glycol, glycerol, and butanol.

13. The method according to claim 1, wherein, The temperature at which the substances are miscible is 120-160℃.

14. The method according to claim 1, wherein, The weight ratio of the nitrogen-containing heavy oil to the polar solvent is 1:0.1-5.

15. The method according to claim 14, wherein, The weight ratio of the nitrogen-containing heavy oil to the polar solvent is 1:0.3-1.

16. The method according to claim 1, wherein, The nonpolar solvent is C8-C. 16 n-alkanes.

17. The method according to claim 1, wherein, The temperature at which the extraction is repeated multiple times is the same as the temperature at which the substances are miscible.

18. The method according to claim 1, wherein, The weight ratio of nitrogen-containing heavy oil and non-polar solvent in the mixture is 1:0.15-0.

5.

19. The method according to claim 1, wherein, The temperature for the repeated extractions is 120-160℃.

20. The method according to claim 1, wherein, The process of repeated extraction includes: i. The mixture is subjected to a first extraction with the non-polar solvent to obtain an extract phase of denitrified liquid 1 and a raffinate phase of nitrogen-containing liquid 1; ii. The nitrogen-containing liquid 1 is subjected to a second extraction with the non-polar solvent to obtain the extract phase as denitrified liquid 2 and the raffinate phase as nitrogen-containing liquid 2; iii. The nitrogen-containing liquid m-1 is extracted with the non-polar solvent to obtain the extract phase as denitrified liquid m and the raffinate phase as nitrogen-containing liquid m; Where m is a positive integer and m≥3.

21. The method according to claim 20, wherein, In the first extraction, the second extraction, ..., the mth extraction, the amount of non-polar solvent added may be the same or different.

22. The method according to claim 21, wherein, The amount of nonpolar solvent added is the same in each of the multiple repeated extraction processes.

23. The method according to claim 1, wherein, The method includes returning the first recovered liquid as a circulating nonpolar solvent and mixing it with the nonpolar solvent.

24. The method according to claim 1, wherein, The method involves mixing multiple raffinate phases and then performing a second solvent recovery to obtain a second recovered liquid and nitrogen-containing oil.

25. The method according to claim 24, wherein, The method includes returning the second recovered liquid as a circulating polar solvent and mixing it with the polar solvent.

26. The method according to any one of claims 1-25, wherein, The nitrogen content in the denitrified oil obtained by this method is 0.01-1 wt%.

27. The method according to claim 26, wherein, The nitrogen content in the denitrified oil obtained by this method is 0.05-0.2 wt%.

28. The method according to any one of claims 1-25, wherein, The denitrified oil obtained by this method is used in the production and processing of carbon materials.

29. The method according to claim 28, wherein, The carbon material is needle coke.

Images