Heavy oil underground reforming viscosity reducer and preparation method thereof

Abstract

The present invention relates to the field of heavy oil mining, and more particularly to a heavy oil underground modification and viscosity reduction agent and a preparation method thereof. The raw materials for preparing the heavy oil underground modification and viscosity reduction agent include: 1-10 parts by weight of cobalt molybdate, 0.1-3.5 parts by weight of ethylenediamine, 5-15 parts by weight of sulfonic acid, and 10-65 parts by weight of water. The heavy oil underground modification and viscosity reduction agent provided in the present invention has the advantages of a simple preparation process, strong universality, and good viscosity reduction effect. It can modify and reduce the viscosity of heavy oil at a relatively low temperature (≤180°C), and the viscosity reduction rate is above 95%.

Description

Technical Field

[0001] The present invention relates to the field of heavy oil mining, and in particular to a heavy oil underground reforming and viscosity reducing agent and a preparation method thereof. Background Art

[0002] Heavy oil production primarily relies on steam stimulation, but multiple rounds of stimulation can increase the content of colloid and asphaltene in the heavy oil, increasing crude oil viscosity and making it difficult to maintain stable production in the later stages. To reduce crude oil viscosity, a viscosity-reducing agent can be injected into the formation simultaneously with steam injection.

[0003] CN110791312A discloses a method for modifying and reducing the viscosity of heavy oil using a non-transition metal catalysis method. The method comprises the following steps: first, adding a low-carbon alcohol and heavy oil in a mass ratio of 1:1-20 to a reaction vessel; second, adding a catalyst in an amount of 0.5-10% by weight to the mixture; third, sealing the reaction vessel, stirring, heating to 180-300°C, maintaining the temperature for 2-24 hours, and cooling to room temperature; and fourth, opening the reaction vessel and pouring out the heavy oil to obtain heavy oil with reduced viscosity.

[0004] CN107142096A discloses a method for biomass-assisted heavy oil autocatalytic reforming and viscosity reduction. Biomass powder is added to the heavy oil and reacted at a temperature of 330-360°C for 30 minutes under the catalytic effect of the metal elements contained in the biomass. The viscosity reduction rate of the heavy oil after the reaction is 82-99%.

[0005] CN106089167A discloses a method for underground catalytic modification and viscosity reduction of heavy oil. The catalyst used in this method is an iron-sulfur cluster compound, which utilizes the "multi-nuclear" molecular structure characteristics of the iron-sulfur cluster compound. During the catalytic reaction, adjacent central metals can synergize with each other, allowing modification and viscosity reduction to be carried out efficiently.

[0006] CN103386323A discloses a modified viscosity-reducing catalyst and a preparation method thereof. The catalyst is prepared by reacting petroleum distillate and a transition metal inorganic salt in an air atmosphere, followed by adding sodium hydroxide or potassium hydroxide and continuing the reaction.

[0007] The modified viscosity reducers used in the above methods generally have high operating temperatures (greater than or equal to 240°C) and need to consider the issue of contact with heavy oil after injection into the formation, which limits their application. Therefore, there is an urgent need to provide a modified viscosity reducer that can achieve good viscosity reduction effects at low temperatures and has good universal applicability. Summary of the Invention

[0008] The purpose of the present invention is to overcome the problems of high operating temperature and poor universality of modified viscosity reducers in the prior art, and to provide a heavy oil underground modified viscosity reducer and a preparation method thereof.

[0009] To achieve the above-mentioned object, the first aspect of the present invention provides a heavy oil underground modification and viscosity reduction agent, wherein the raw materials for preparing the heavy oil underground modification and viscosity reduction agent include: 1-10 parts by weight of cobalt molybdate, 0.1-3.5 parts by weight of ethylenediamine, 5-15 parts by weight of sulfonic acid, and 10-65 parts by weight of water.

[0010] A second aspect of the present invention provides a method for preparing a heavy oil underground reforming and viscosity reducing agent, wherein the method comprises the following steps:

[0011] (1) Ethylenediamine and sulfonic acid react in water to obtain an ammonium salt solution;

[0012] (2) adding cobalt molybdate and sulfonic acid into the ammonium salt solution to react and obtain the heavy oil underground reforming viscosity reducer.

[0013] The underground heavy oil reforming and viscosity reducing agent provided by the present invention has the advantages of simple preparation process, strong universality, good viscosity reducing effect, etc. It can cause heavy oil to undergo reforming and viscosity reducing reaction at a relatively low temperature (≤180°C). After the reaction, the viscosity of the heavy oil is greatly reduced, and the viscosity reduction rate is above 95%. DETAILED DESCRIPTION

[0014] The endpoints of the ranges and any values ​​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 endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0015] A first aspect of the present invention provides a heavy oil underground reforming and viscosity reducing agent, wherein the raw materials for preparing the heavy oil underground reforming and viscosity reducing agent include: 1-10 parts by weight of cobalt molybdate, 0.1-3.5 parts by weight of ethylenediamine, 5-15 parts by weight of sulfonic acid, and 10-65 parts by weight of water.

[0016] Among them, in the present invention, the underground heavy oil reforming and viscosity reduction agent can simultaneously exert the catalytic activity advantages of the two metal centers, molybdenum and cobalt, and the synergistic effect of molybdenum and cobalt can improve efficiency, so that it can reform and reduce the viscosity of heavy oil, extra heavy oil, and even super heavy oil under relatively low formation temperature conditions (less than or equal to 180°C).

[0017] In some embodiments of the present invention, the weight proportion of cobalt molybdate in the raw material for preparing the heavy oil underground reforming and viscosity reducing agent can be 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, and any value in the range formed by any two of these values, preferably 5-6.

[0018] In some embodiments of the present invention, the weight proportion of ethylenediamine in the raw material for preparing the heavy oil underground reforming and viscosity reducing agent can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.7, 2, 2.3, 2.5, 3, 3.3, 3.5, and any value in the range formed by any two of these point values, preferably 1.5-2.5.

[0019] In some embodiments of the present invention, the weight proportion of sulfonic acid in the raw material for preparing the heavy oil underground reforming and viscosity reducing agent can be 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 10.5, 11, 11.5, 12, 12.5, 13, 13.5, 14, 14.5, 15, and any value in the range formed by any two of these values, preferably 10-14.

[0020] In some embodiments of the present invention, the weight proportion of water in the raw material for preparing the heavy oil underground reforming and viscosity reducing agent can be 10, 15, 18, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, and any value in the range formed by any two of these values, preferably 40-60.

[0021] In some embodiments of the present invention, the sulfonic acid is selected from one or more of methanesulfonic acid, 2-aminoethanesulfonic acid, benzenesulfonic acid, and p-toluenesulfonic acid, preferably p-toluenesulfonic acid.

[0022] A second aspect of the present invention provides a method for preparing a heavy oil underground reforming and viscosity reducing agent, wherein the method comprises the following steps:

[0023] (1) Ethylenediamine and sulfonic acid react in water to obtain an ammonium salt solution;

[0024] (2) adding cobalt molybdate and sulfonic acid into the ammonium salt solution to react and obtain the heavy oil underground reforming viscosity reducer.

[0025] In step (1):

[0026] In one embodiment of the present invention, the sulfonic acid is selected from one or more of methanesulfonic acid, 2-aminoethanesulfonic acid, benzenesulfonic acid, and p-toluenesulfonic acid, preferably p-toluenesulfonic acid.

[0027] In one embodiment of the present invention, the mass ratio of ethylenediamine, sulfonic acid and water is (0.1-3.5):(4-8):(10-65).

[0028] In one embodiment of the present invention, the reaction conditions of ethylenediamine and sulfonic acid in water include: carrying out under the protection of inert gas, the reaction temperature is 40-90° C., and the reaction time is 1-4 hours.

[0029] In one embodiment of the present invention, the reaction conditions of ethylenediamine and sulfonic acid in water further include: adding the aqueous solution of ethylenediamine dropwise into the aqueous solution of sulfonic acid.

[0030] In step (2):

[0031] In one embodiment of the present invention, the cobalt molybdate may be a commercially available product or may be synthesized according to a known method.

[0032] In one embodiment of the present invention, the synthesis method of cobalt molybdate comprises: adding a sodium molybdate solution dropwise to a cobalt chloride solution at 35-85° C. for a reaction of 0.5-3 hours to obtain cobalt molybdate.

[0033] Preferably, the cobalt chloride solution comprises 1.5-6.5 g of cobalt chloride and 5-15 mL of water; preferably, the sodium molybdate solution comprises 1.8-6 g of sodium molybdate and 5-15 mL of water; preferably, after the reaction, filtration, washing, and vacuum drying (dried in vacuum at 80-110° C. for 24-48 hours) are performed in sequence to obtain cobalt molybdate.

[0034] In one embodiment of the present invention, the mass ratio of ethylenediamine added in step (1), cobalt molybdate added in step (2) and sulfonic acid added in step (2) is (0.1-3.5):(1-10):(1-8.5).

[0035] In one embodiment of the present invention, the reaction conditions of the cobalt molybdate, sulfonic acid and ammonium salt solution include: carrying out under the protection of inert gas, the reaction temperature is 80-95° C., and the reaction time is 1-4 hours.

[0036] In one embodiment of the present invention, after the reaction of cobalt molybdate, sulfonic acid and ammonium salt is completed, filtration, washing and vacuum drying (dried in vacuum at 80-110° C. for 24-48 hours) are performed to obtain a heavy oil underground reforming and viscosity reducing agent.

[0037] The present invention will be described in detail below through examples.

[0038] In the following examples, the preparation of cobalt molybdate solid:

[0039] Dissolve 4.5 g of cobalt chloride in 15 mL of deionized water to obtain a cobalt chloride aqueous solution; dissolve 5.5 g of sodium molybdate in 15 mL of deionized water to obtain a sodium molybdate aqueous solution; place the cobalt chloride aqueous solution in a three-necked flask, introduce high-purity nitrogen gas, and heat to 60° C. in a water bath; add the sodium molybdate aqueous solution dropwise to the cobalt chloride aqueous solution while stirring, react at a constant temperature for 2 hours, filter, wash with distilled water, and dry in a vacuum at 110° C. for 24 hours to obtain cobalt molybdate.

[0040] The viscosities used in the examples of the present invention were measured using a Brookfield DV-III programmable viscometer. The crude oil group composition changes used in the examples of the present invention were calculated by weight using column chromatography separation methods in accordance with the Petroleum and Natural Gas Industry Standard of the People's Republic of China, "Analysis of Soluble Organic Matter in Rocks and Crude Oil Group Composition" (SY / T5119-2008).

[0041] Example 1

[0042] (1) A p-toluenesulfonic acid aqueous solution (6 g p-toluenesulfonic acid, 15 mL deionized water) was added dropwise to a three-necked flask, high-purity nitrogen was introduced, and the flask was heated to 60°C in a water bath. An ethylenediamine aqueous solution (1.8 g ethylenediamine, 25 mL deionized water) was slowly added dropwise to the p-toluenesulfonic acid aqueous solution and the mixture was reacted at this temperature for 2 h to obtain an ammonium salt solution;

[0043] (2) The water bath temperature of the ammonium salt solution was raised to 95° C., 4.0 g of cobalt molybdate and 6.0 g of p-toluenesulfonic acid were added, and the mixture was reacted at a constant temperature for 3 h. The mixture was filtered, washed with distilled water, and dried in a vacuum at 110° C. for 24 h to obtain a heavy oil underground modification and viscosity reducer A.

[0044] Heavy oil underground reforming viscosity reducer A, water, and Shengli Oilfield extra-heavy oil (well number CJC373-P38, viscosity of 56,000 mPa.s at 50°C) were mixed in a mass ratio of 0.35:0.3:0.35 and placed in a high-pressure reactor for reaction at 180°C for 24 hours. After the reaction, testing showed that the viscosity reduction rate of the Shengli Oilfield extra-heavy oil (well number CJC373-P38, viscosity of 56,000 mPa.s at 50°C) reached 97.83%, with 15.76% of the heavy components being cracked into light components. This demonstrates that the bimetallic core reforming viscosity reducer has excellent low-temperature reforming and viscosity reduction effects.

[0045] Heavy oil underground reforming viscosity reducer A, water, and Shengli Oilfield extra-heavy oil (Tuo 826-P4, viscosity of 158,000 mPa.s at 50°C) were mixed in a mass ratio of 0.35:0.3:0.35 and placed in a high-pressure reactor for reaction at 180°C for 24 hours. After the reaction, testing showed that the viscosity reduction rate of the Shengli Oilfield extra-heavy oil (Tuo 826-P4, viscosity of 158,000 mPa.s at 50°C) reached 94.54%, with 15.97% of the heavy components being cracked into light components. This indicates that the bimetallic core reforming viscosity reducer has a good low-temperature reforming and viscosity reduction effect.

[0046] Example 2

[0047] (1) A methanesulfonic acid aqueous solution (4 g methanesulfonic acid, 24 mL deionized water) was added dropwise to a three-necked flask, high-purity nitrogen was introduced, and the flask was heated to 45°C in a water bath. An ethylenediamine aqueous solution (0.8 g ethylenediamine, 18 mL deionized water) was slowly added dropwise to the methanesulfonic acid aqueous solution, and the reaction was carried out at a constant temperature for 1 h to obtain an ammonium salt solution;

[0048] (2) The water bath temperature of the ammonium salt solution was raised to 90°C, 1.8 g of cobalt molybdate and 3.5 g of methanesulfonic acid were added, and the mixture was reacted at constant temperature for 2 h. The mixture was filtered, washed with distilled water, and dried in a vacuum at 110°C for 24 h to obtain a heavy oil underground modification and viscosity reducer B.

[0049] Heavy oil underground reforming viscosity reducer B, water, and Shengli Oilfield extra-heavy oil (well number CJC373-P38, viscosity of 56,000 mPa.s at 50°C) were mixed in a mass ratio of 0.35:0.30:0.35 and placed in an autoclave for reaction at 180°C for 24 hours. After the reaction, testing showed that the viscosity reduction rate of the Shengli Oilfield extra-heavy oil (well number CJC373-P38, viscosity of 56,000 mPa.s at 50°C) reached 98.43%, and 15.96% of the heavy components were cracked into light components.

[0050] Heavy oil underground reforming viscosity reducer B, water, and Shengli Oilfield extra-heavy oil (well number Tuo 826-P4, viscosity of 158,000 mPa.s at 50°C) were mixed in a mass ratio of 0.35:0.30:0.35 and placed in a high-pressure reactor for reaction at 180°C for 24 hours. After the reaction, testing showed that the viscosity reduction rate of the Shengli Oilfield extra-heavy oil (well number Tuo 826-P4, viscosity of 158,000 mPa.s at 50°C) reached 96.93%, and 14.66% of the heavy components were cracked into light components.

[0051] Example 3

[0052] (1) A 2-aminoethanesulfonic acid aqueous solution (8 g 2-aminoethanesulfonic acid, 20 mL deionized water) was added dropwise to a three-necked flask, and high-purity nitrogen was introduced. The flask was heated to 85°C in a water bath. An ethylenediamine aqueous solution (2.5 g ethylenediamine, 40 mL deionized water) was slowly added dropwise to the 2-aminoethanesulfonic acid aqueous solution. The reaction was continued at this temperature for 2.5 h to obtain an ammonium salt solution.

[0053] (2) The water bath temperature of the ammonium salt solution was raised to 95°C, 6.0 g of cobalt molybdate and 6.0 g of 2-aminoethanesulfonic acid were added, and the mixture was reacted at a constant temperature for 4 h. The mixture was filtered, washed with distilled water, and dried in a vacuum at 110°C for 24 h to obtain a heavy oil underground modification viscosity reducer C.

[0054] Heavy oil underground reforming viscosity reducer C, water, and Shengli Oilfield extra-heavy oil (well CJC373-P38, viscosity 56,000 mPa.s at 50°C) were mixed in a mass ratio of 0.35:0.30:0.35 and placed in an autoclave for reaction at 180°C for 24 hours. After the reaction, testing showed that the viscosity reduction rate of the Shengli Oilfield extra-heavy oil (well CJC373-P38, viscosity 56,000 mPa.s at 50°C) reached 98.87%, and 16.45% of the heavy components were cracked into light components.

[0055] Heavy oil underground reforming viscosity reducer C, water, and Shengli Oilfield extra-heavy oil (well number Tuo 826-P4, viscosity of 158,000 mPa.s at 50°C) were mixed in a mass ratio of 0.35:0.30:0.35 and placed in a high-pressure reactor for reaction at 180°C for 24 hours. After the reaction, testing showed that the viscosity reduction rate of the Shengli Oilfield extra-heavy oil (well number Tuo 826-P4, viscosity of 158,000 mPa.s at 50°C) reached 97.47%, and 15.45% of the heavy components were cracked into light components.

[0056] Example 4

[0057] (1) A p-toluenesulfonic acid aqueous solution (5.5 g p-toluenesulfonic acid, 18 mL deionized water) was added dropwise to a three-necked flask, high-purity nitrogen was introduced, and the flask was heated to 65°C in a water bath. An ethylenediamine aqueous solution (1.5 g ethylenediamine, 30 mL deionized water) was slowly added dropwise to the p-toluenesulfonic acid aqueous solution, and the reaction was carried out at a constant temperature for 3 h to obtain an ammonium salt solution;

[0058] (2) The water bath temperature of the ammonium salt solution was raised to 95°C, 3.8 g of cobalt molybdate and 7.0 g of p-toluenesulfonic acid were added, and the mixture was reacted at a constant temperature for 3 h. The mixture was filtered, washed with distilled water, and dried in a vacuum at 110°C for 24 h to obtain a heavy oil underground modification and viscosity reducer D.

[0059] Heavy oil underground reforming viscosity reducer D, water and Shengli Oilfield super heavy oil (well number Zheng 411-P35, viscosity of 115000 mPa.s at 50°C) were mixed in a mass ratio of 0.35:0.30:0.35 and placed in a high-pressure reactor for reaction at 180°C for 24 hours.

[0060] After the reaction, testing showed that the viscosity reduction rate of Shengli Oilfield's extra-heavy oil reached 96.38%, and 14.56% of the heavy components were cracked into light components.

[0061] Example 5

[0062] (1) A p-toluenesulfonic acid aqueous solution (4 g p-toluenesulfonic acid, 24 mL deionized water) was added dropwise to a three-necked flask, high-purity nitrogen was introduced, and the flask was heated to 50°C in a water bath. An ethylenediamine aqueous solution (2 g ethylenediamine, 25 mL deionized water) was slowly added dropwise to the p-toluenesulfonic acid aqueous solution, and the reaction was carried out at a constant temperature for 2 h to obtain an ammonium salt solution;

[0063] (2) The water bath temperature of the ammonium salt solution was raised to 95°C, 2.0 g of cobalt molybdate and 5.0 g of p-toluenesulfonic acid were added, and the mixture was reacted at a constant temperature for 2.5 h. The mixture was filtered, washed with distilled water, and dried in a vacuum at 110°C for 24 h to obtain a heavy oil underground modification and viscosity reducer E.

[0064] Heavy oil underground reforming viscosity reducer E, water and Shengli Oilfield super heavy oil (well number Zheng 411-P35, viscosity of 115000 mPa.s at 50°C) were mixed in a mass ratio of 0.35:0.30:0.35 and placed in a high-pressure reactor for reaction at 180°C for 24 hours.

[0065] After the reaction, the super-heavy oil from Shengli Oilfield (well number Zheng 411-P35, with a viscosity of 115,000 mPa.s at 50°C) was tested and found to have a viscosity reduction rate of 97.33%, with 15.32% of the heavy components cracked into light components.

[0066] Example 6

[0067] (1) A p-toluenesulfonic acid aqueous solution (7.5 g p-toluenesulfonic acid, 24 mL deionized water) was added dropwise to a three-necked flask, high-purity nitrogen was introduced, and the flask was heated to 80°C in a water bath. An ethylenediamine aqueous solution (2 g ethylenediamine, 30 mL deionized water) was slowly added dropwise to the p-toluenesulfonic acid aqueous solution, and the reaction was carried out at a constant temperature for 2.5 h to obtain an ammonium salt solution;

[0068] (2) The water bath temperature of the ammonium salt solution was raised to 95°C, 6.5 g of cobalt molybdate and 7.0 g of p-toluenesulfonic acid were added, and the mixture was reacted at a constant temperature for 3 h. The mixture was filtered, washed with distilled water, and dried in a vacuum at 110°C for 24 h to obtain a heavy oil underground modification and viscosity reducer F.

[0069] Heavy oil underground reforming viscosity reducer F, water and Shengli Oilfield super heavy oil (well number Zheng 411-P35, viscosity of 115000 mPa.s at 50°C) were mixed in a mass ratio of 0.35:0.30:0.35 and placed in a high-pressure reactor for reaction at 180°C for 24 hours.

[0070] After the reaction, it was tested that the viscosity reduction rate of Shengli Oilfield's super-heavy oil (well number Zheng 411-P35, viscosity of 115,000 mPa.s at 50°C) reached 97.89%, and 13.10% of the heavy components were cracked into light components.

[0071] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A heavy oil underground reforming and viscosity reducing agent, characterized in that: The raw materials for preparing the heavy oil underground reforming and viscosity reducing agent include: 1-10 parts by weight of cobalt molybdate, 0.1-3.5 parts by weight of ethylenediamine, 5-15 parts by weight of sulfonic acid, and 10-65 parts by weight of water.

2. The heavy oil underground reforming and viscosity reducing agent according to claim 1, wherein: The raw materials for preparing the heavy oil underground reforming and viscosity reducing agent include: 5-6 parts by weight of cobalt molybdate, 1.5-2.5 parts by weight of ethylenediamine, 10-14 parts by weight of sulfonic acid, and 40-60 parts by weight of water.

3. The heavy oil underground reforming and viscosity reducing agent according to claim 1 or 2, wherein: The sulfonic acid is selected from one or more of methanesulfonic acid, 2-aminoethanesulfonic acid, benzenesulfonic acid, and p-toluenesulfonic acid.

4. The heavy oil underground reforming and viscosity reducing agent according to claim 3, wherein: The sulfonic acid is p-toluenesulfonic acid.

5. A method for preparing a heavy oil underground reforming and viscosity reducing agent, characterized in that: The method comprises the following steps: (1) Ethylenediamine and sulfonic acid react in water to obtain an ammonium salt solution; (2) adding cobalt molybdate and sulfonic acid into the ammonium salt solution to react and obtain the heavy oil underground reforming viscosity reducer.

6. The preparation method according to claim 5, wherein The sulfonic acid is selected from one or more of methanesulfonic acid, 2-aminoethanesulfonic acid, benzenesulfonic acid, and p-toluenesulfonic acid.

7. The preparation method according to claim 5 or 6, wherein The sulfonic acid is p-toluenesulfonic acid.

8. The preparation method according to claim 5, wherein The mass ratio of the ethylenediamine, sulfonic acid and water is (0.1-3.5): (4-8): (10-65).

9. The preparation method according to claim 5, wherein The reaction conditions of the ethylenediamine and sulfonic acid in water include: carrying out the reaction under the protection of inert gas, the reaction temperature is 40-90° C., and the reaction time is 1-4 hours.

10. The preparation method according to claim 5, wherein The synthesis method of cobalt molybdate comprises: adding a sodium molybdate solution dropwise into a cobalt chloride solution at 35-85° C. for reaction for 0.5-3 hours to obtain cobalt molybdate.

11. The preparation method according to claim 10, wherein The cobalt chloride solution includes 1.5-6.5 g of cobalt chloride and 5-15 mL of water.

12. The preparation method according to claim 10, wherein The sodium molybdate solution includes 1.8-6 g of sodium molybdate and 5-15 mL of water.

13. The preparation method according to claim 10, wherein After the reaction, the product is filtered, washed and vacuum dried to obtain cobalt molybdate.

14. The preparation method according to claim 5, wherein The mass ratio of ethylenediamine and cobalt molybdate added in step (1) to sulfonic acid added in step (2) is (0.1-3.5):(1-10):(1-8.5).

15. The preparation method according to claim 5, wherein The reaction conditions of the cobalt molybdate, sulfonic acid and ammonium salt solution include: carrying out the reaction under the protection of inert gas, the reaction temperature is 80-95° C., and the reaction time is 1-4 hours.