Method for oxidative desulfurization by using cobalt-containing positive electrode material of waste lithium battery

Abstract

The invention belongs to the technical field of petrochemical engineering, and discloses a method for oxidative desulfurization by using a cobalt-containing positive electrode material of a waste lithium battery, which comprises the following steps: adding the cobalt-containing positive electrode material of the waste lithium battery and dilute sulphuric acid into fuel oil, stirring for reaction, standing for layering, and obtaining an upper oil phase which is the desulfurized fuel oil. According to the method, the cobalt-containing positive electrode material is used as an oxidizing agent, the problem that heterocyclic sulfides in the fuel oil are difficult to remove is solved, no additional solid waste is generated, after trivalent cobalt in the positive electrode material is reduced, respective recovery of cobalt and lithium is facilitated, the green development concept is met, the cost is low, and a new thought is provided for industrial application.

Description

Technical Field

[0001] The invention belongs to the technical field of petrochemical industry, and in particular relates to a method for oxidative desulfurization using cobalt-containing positive electrode materials of waste lithium batteries. Background Art

[0002] With the rapid development of my country's economy, the demand for gasoline, diesel and other fuels has increased significantly. The organic sulfur in the fuel will release polluting gas SO during the combustion process. x These polluting gases are discharged into the atmosphere, easily forming smog (PM2.5) and acid rain, leading to serious environmental problems. Therefore, it is necessary to remove sulfides from diesel as much as possible. Hydrogenation technology is used industrially to achieve desulfurization, but the hydrogenation reaction conditions are harsh (high temperature and high pressure) and the octane number loss is large, resulting in high production costs for clean fuel and substandard fuel quality. Therefore, more efficient and gentle processes are urgently needed to improve fuel quality.

[0003] Therefore, some non-hydrogenation technologies have developed rapidly, such as oxidative desulfurization. Oxidative desulfurization currently uses hydrogen peroxide and air as oxidants. However, hydrogen peroxide is very unstable, easily self-decomposes, and has an explosion risk when stored in large quantities. Although air is low-cost and stable in nature, its oxidizing ability is relatively weak. There are also solid oxidants such as potassium permanganate and potassium dichromate, but these will produce solid waste. In addition, the above-mentioned oxidants have a very low conversion rate for thiophene sulfides, which are more difficult to remove in oil products. Therefore, it is necessary to develop new oxidative desulfurization agents and oxidative desulfurization methods. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to address the shortcomings of the existing technology and provide a method for oxidative desulfurization using cobalt-containing positive electrode materials of waste lithium batteries. The use of cobalt-containing positive electrode materials as oxidants solves the problem of difficult removal of heterocyclic sulfides in fuel, and does not generate additional solid waste. After the trivalent cobalt in the positive electrode material is reduced, it also helps to recover cobalt and lithium separately.

[0005] In order to solve the technical problem raised by the present invention, the present invention provides a method for oxidative desulfurization using cobalt-containing positive electrode materials of waste lithium batteries. The cobalt-containing positive electrode materials of waste lithium batteries and dilute sulfuric acid are added to fuel, stirred for reaction, and allowed to stand for stratification. The upper oil phase is the desulfurized fuel.

[0006] In the above solution, the cobalt-containing positive electrode material of the waste lithium battery is lithium cobalt oxide or ternary material, which is in powder form.

[0007] In the above scheme, the mass fraction of the dilute sulfuric acid is 50-70%.

[0008] In the above scheme, the mass ratio of the cobalt-containing positive electrode material of the waste lithium battery to the dilute sulfuric acid is 1:(2-4).

[0009] In the above solution, the fuel oil is one of kerosene and diesel oil.

[0010] In the above solution, the content of thiophene sulfides in the fuel oil is 100 - 10,000 ppm.

[0011] Furthermore, the thiophene sulfides are one or several of dibenzothiophene, benzothiophene, and 4,6 - dimethyldibenzothiophene.

[0012] In the above solution, the molar ratio of the cobalt - containing cathode material of the waste lithium battery to the thiophene sulfides in the fuel oil is (10 - 90):1.

[0013] Furthermore, when the cobalt - containing cathode material of the waste lithium battery is lithium cobaltate, the molar ratio to the thiophene sulfides in the fuel oil is (50 - 90):1.

[0014] Furthermore, when the cobalt - containing cathode material of the waste lithium battery is ternary material, the molar ratio to the thiophene sulfides in the fuel oil is (10 - 20):1.

[0015] In the above solution, the stirring speed of the stirring reaction is 600 - 1000 rpm, the reaction temperature is 50 - 80 °C, and the reaction time is 30 - 240 min.

[0016] Preferably, the stirring speed of the stirring reaction is 900 - 1000 rpm, the reaction temperature is 70 - 80 °C, and the reaction time is 120 - 240 min.

[0017] The conversion rate of dibenzothiophene in the method of the present invention is ≥ 40%, preferably ≥ 90% under preferred conditions, the conversion rate of benzothiophene is ≥ 70%, and the conversion rate of 4,6 - dimethyldibenzothiophene is ≥ 40%.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] 1) The present invention utilizes the strong oxidizing property of the cobalt - containing cathode material (lithium cobaltate or ternary material) of the waste lithium battery under acidic conditions to oxidize and remove thiophene sulfides in the oil product. Among them, the trivalent cobalt in the cobalt - containing cathode material serves as the oxidant, and dilute sulfuric acid serves as the catalyst. Sulfuric acid can leach the trivalent cobalt in the cobalt - containing cathode material, and then oxidize the thiophene sulfides in the oil product into sulfone substances with stronger polarity, thereby achieving the removal purpose.

[0020] 2) The oxidation reaction conditions of the present invention are mild, without high temperature and high pressure. The oxidation reaction and extraction are carried out simultaneously, the process is simple, and the desulfurization effect is good. The oxidant of the present invention is sourced from waste lithium batteries, which conforms to the concept of green development, has low cost, higher safety, and does not generate additional solid waste. After the trivalent cobalt in the cathode material is reduced, it also helps to separately recover cobalt and lithium. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a comparison diagram before and after oxidative desulfurization in Example 1 of the present invention.

[0022] Figure 2 It is a liquid chromatography comparison diagram before and after oxidative desulfurization in Example 1 of the present invention.

[0023] Figure 3 It is a liquid chromatography comparison diagram before and after oxidative desulfurization in Example 12 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] To better understand the present invention, the content of the present invention will be further clarified below in conjunction with embodiments, but the content of the present invention is not limited to the following embodiments.

[0025] Example 1

[0026] The waste lithium battery cathode material used in the present invention is specifically lithium cobaltate; dilute sulfuric acid with a mass fraction of 70% is used; a model oil formed by mixing dibenzothiophene and n-hexadecane is used to simulate real diesel, and the initial sulfur content is 1000 ppm.

[0027] Taking the waste lithium battery cobalt-containing cathode material and dilute sulfuric acid in a mass ratio of 1:4 and adding them to the model oil, the molar ratio of the waste lithium battery cobalt-containing cathode material to dibenzothiophene in the model oil is 90:1. After stirring and reacting at 70 °C at a stirring rate of 990 rpm for 120 min, it is allowed to stand and separate layers. The upper oil phase is the desulfurized model oil.

[0028] Taking the upper model oil for detection, the conversion rate of dibenzothiophene is 99.88%; the lower layer is washed with water, filtered, and dried to obtain the mass of the unreacted lithium cobaltate black solid, and then combined with the mass of the cathode material taken before the reaction, the conversion rate of lithium cobaltate is calculated to be 67.15%.

[0029] Figure 1 The comparison diagram before and after oxidative desulfurization in Example 1 is shown. It can be found that after the oxidation reaction, the lower layer solution shows a red color, indicating the presence of cobalt sulfate in it, which can illustrate that the cobalt in lithium cobaltate is reduced from trivalent to divalent, and an oxidation reaction has occurred. Figure 3 It is a liquid chromatography comparison diagram before and after oxidative desulfurization in Example 1. It can be seen that the peak value of dibenzothiophene has decreased significantly after the reaction, indicating that most of the sulfides have been removed.

[0030] Example 2

[0031] The waste lithium - ion battery cathode material used in the present invention is specifically lithium cobaltate; dilute sulfuric acid with a mass fraction of 70% is used; a model oil formed by mixing benzothiophene and n - hexadecane is used to simulate real diesel, and the initial sulfur content is 1000 ppm.

[0032] Take the waste lithium - ion battery cobalt - containing cathode material and dilute sulfuric acid in a mass ratio of 1:4, add them to the model oil. The molar ratio of the waste lithium - ion battery cobalt - containing cathode material to benzothiophene in the model oil is 90:1. After stirring and reacting at 70 °C for 120 min at a stirring rate of 990 rpm, let it stand for stratification. The upper oil phase is the desulfurized model oil.

[0033] Take the upper - layer model oil for detection. The conversion rate of benzothiophene is 77.48%; the lower layer is washed with water, filtered, and dried to obtain the mass of the unreacted black lithium cobaltate solid. Then, combined with the mass of the cathode material taken before the reaction, the conversion rate of lithium cobaltate is calculated to be 65.60%.

[0034] Example 3

[0035] The waste lithium - ion battery cathode material used in the present invention is specifically lithium cobaltate; dilute sulfuric acid with a mass fraction of 70% is used; a model oil formed by mixing 4,6 - dimethyldibenzothiophene and n - hexadecane is used to simulate real diesel, and the initial sulfur content is 1000 ppm.

[0036] Take the waste lithium - ion battery cobalt - containing cathode material and dilute sulfuric acid in a mass ratio of 1:4, add them to the model oil. The molar ratio of the waste lithium - ion battery cobalt - containing cathode material to 4,6 - dimethyldibenzothiophene in the model oil is 90:1. After stirring and reacting at 70 °C for 120 min at a stirring rate of 990 rpm, let it stand for stratification. The upper oil phase is the desulfurized model oil.

[0037] Take the upper - layer model oil for detection. The conversion rate of 4,6 - dimethyldibenzothiophene is 42.22%; the lower layer is washed with water, filtered, and dried to obtain the mass of the unreacted black lithium cobaltate solid. Then, combined with the mass of the cathode material taken before the reaction, the conversion rate of lithium cobaltate is calculated to be 53.56%.

[0038] Example 4

[0039] The waste lithium - ion battery cathode material used in the present invention is specifically lithium cobaltate; dilute sulfuric acid with a mass fraction of 50% is used; a model oil formed by mixing dibenzothiophene and n - hexadecane is used to simulate real diesel, and the initial sulfur content is 1000 ppm.

[0040] Take the cobalt-containing cathode material of waste lithium batteries and dilute sulfuric acid at a mass ratio of 1:4, add them to the model oil. The molar ratio of the cobalt-containing cathode material of waste lithium batteries to dibenzothiophene in the model oil is 90:1. After stirring and reacting at 70 °C at a stirring rate of 990 rpm for 120 min, let it stand for stratification. The upper oil phase is the desulfurized model oil.

[0041] Take the upper model oil for detection. The conversion rate of dibenzothiophene is 40.32%; the lower layer is washed with water, filtered, and dried to obtain the mass of the unreacted cobalt lithium oxide black solid. Then, combined with the mass of the cathode material taken before the reaction, the conversion rate of cobalt lithium oxide is calculated to be 55.89%.

[0042] Example 5

[0043] The cobalt-containing cathode material of waste lithium batteries used in the present invention is specifically cobalt lithium oxide; dilute sulfuric acid with a mass fraction of 70% is used; a model oil formed by mixing dibenzothiophene and n-hexadecane is used to simulate real diesel, and the initial sulfur content is 1000 ppm.

[0044] Take the cobalt-containing cathode material of waste lithium batteries and dilute sulfuric acid at a mass ratio of 1:3, add them to the model oil. The molar ratio of the cobalt-containing cathode material of waste lithium batteries to dibenzothiophene in the model oil is 90:1. After stirring and reacting at 70 °C at a stirring rate of 990 rpm for 120 min, let it stand for stratification. The upper oil phase is the desulfurized model oil.

[0045] Take the upper model oil for detection. The conversion rate of dibenzothiophene is 71.76%; the lower layer is washed with water, filtered, and dried to obtain the mass of the unreacted cobalt lithium oxide black solid. Then, combined with the mass of the cathode material taken before the reaction, the conversion rate of cobalt lithium oxide is calculated to be 68.64%.

[0046] Example 6

[0047] The cobalt-containing cathode material of waste lithium batteries used in the present invention is specifically cobalt lithium oxide; dilute sulfuric acid with a mass fraction of 70% is used; a model oil formed by mixing dibenzothiophene and n-hexadecane is used to simulate real diesel, and the initial sulfur content is 1000 ppm.

[0048] Take the cobalt-containing cathode material of waste lithium batteries and dilute sulfuric acid at a mass ratio of 1:4, add them to the model oil. The molar ratio of the cobalt-containing cathode material of waste lithium batteries to dibenzothiophene in the model oil is 50:1. After stirring and reacting at 70 °C at a stirring rate of 990 rpm for 120 min, let it stand for stratification. The upper oil phase is the desulfurized model oil.

[0049] Take the upper model oil for detection. The conversion rate of dibenzothiophene is 47.85%; the lower layer is washed with water, filtered, and dried to obtain the mass of the unreacted cobalt lithium oxide black solid. Then, combined with the mass of the cathode material taken before the reaction, the conversion rate of cobalt lithium oxide is calculated to be 30.24%.

[0050] Example 7

[0051] The waste lithium - ion battery cathode material used in the present invention is specifically lithium cobaltate; dilute sulfuric acid with a mass fraction of 70% is used; a model oil formed by mixing dibenzothiophene and n - hexadecane is used to simulate real diesel, and the initial sulfur content is 1000 ppm.

[0052] Take the waste lithium - ion battery cobalt - containing cathode material and dilute sulfuric acid in a mass ratio of 1:4 and add them to the model oil. The molar ratio of the cobalt - containing cathode material of the waste lithium - ion battery to dibenzothiophene in the model oil is 70:1. After stirring and reacting at 70 °C at a stirring rate of 990 rpm for 120 min, it is allowed to stand and separate layers. The upper oil phase is the desulfurized model oil.

[0053] Take the upper - layer model oil for detection. The conversion rate of dibenzothiophene is 73.63%; the lower layer is washed with water, filtered, and dried to obtain the mass of the unreacted black lithium cobaltate solid. Then, combined with the mass of the cathode material taken before the reaction, the conversion rate of lithium cobaltate is calculated to be 74.86%.

[0054] Example 8

[0055] The waste lithium - ion battery cathode material used in the present invention is specifically lithium cobaltate; dilute sulfuric acid with a mass fraction of 70% is used; a model oil formed by mixing dibenzothiophene and n - hexadecane is used to simulate real diesel, and the initial sulfur content is 1000 ppm.

[0056] Take the waste lithium - ion battery cobalt - containing cathode material and dilute sulfuric acid in a mass ratio of 1:4 and add them to the model oil. The molar ratio of the cobalt - containing cathode material of the waste lithium - ion battery to dibenzothiophene in the model oil is 90:1. After stirring and reacting at 50 °C at a stirring rate of 990 rpm for 120 min, it is allowed to stand and separate layers. The upper oil phase is the desulfurized model oil.

[0057] Take the upper - layer model oil for detection. The conversion rate of dibenzothiophene is 71.70%; the lower layer is washed with water, filtered, and dried to obtain the mass of the unreacted black lithium cobaltate solid. Then, combined with the mass of the cathode material taken before the reaction, the conversion rate of lithium cobaltate is calculated to be 47.38%.

[0058] Example 9

[0059] The waste lithium - ion battery cathode material used in the present invention is specifically lithium cobaltate; dilute sulfuric acid with a mass fraction of 70% is used; a model oil formed by mixing dibenzothiophene and n - hexadecane is used to simulate real diesel, and the initial sulfur content is 1000 ppm.

[0060] Take the cobalt-containing cathode material of waste lithium batteries and dilute sulfuric acid at a mass ratio of 1:4, add them to the model oil. The molar ratio of the cobalt-containing cathode material of waste lithium batteries to dibenzothiophene in the model oil is 90:1. After stirring and reacting at 80 °C at a stirring rate of 990 rpm for 120 min, let it stand for stratification. The upper oil phase is the desulfurized model oil.

[0061] Take the upper model oil for detection. The conversion rate of dibenzothiophene is 98.12%; the lower layer is washed with water, filtered, and dried to obtain the mass of the unreacted cobalt lithium oxide black solid. Then, combined with the mass of the cathode material taken before the reaction, the conversion rate of cobalt lithium oxide is calculated to be 53.85%.

[0062] Example 10

[0063] The cobalt-containing cathode material of waste lithium batteries used in the present invention is specifically lithium cobalt oxide; dilute sulfuric acid with a mass fraction of 70% is used; a model oil formed by mixing dibenzothiophene and n-hexadecane is used to simulate real diesel, and the initial sulfur content is 1000 ppm.

[0064] Take the cobalt-containing cathode material of waste lithium batteries and dilute sulfuric acid at a mass ratio of 1:4, add them to the model oil. The molar ratio of the cobalt-containing cathode material of waste lithium batteries to dibenzothiophene in the model oil is 90:1. After stirring and reacting at 70 °C at a stirring rate of 990 rpm for 60 min, let it stand for stratification. The upper oil phase is the desulfurized model oil.

[0065] Take the upper model oil for detection. The conversion rate of dibenzothiophene is 99.82%; the lower layer is washed with water, filtered, and dried to obtain the mass of the unreacted cobalt lithium oxide black solid. Then, combined with the mass of the cathode material taken before the reaction, the conversion rate of cobalt lithium oxide is calculated to be 49.67%.

[0066] Example 11

[0067] The cobalt-containing cathode material of waste lithium batteries used in the present invention is specifically lithium cobalt oxide; dilute sulfuric acid with a mass fraction of 70% is used; a model oil formed by mixing dibenzothiophene and n-hexadecane is used to simulate real diesel, and the initial sulfur content is 1000 ppm.

[0068] Take the cobalt-containing cathode material of waste lithium batteries and dilute sulfuric acid at a mass ratio of 1:4, add them to the model oil. The molar ratio of the cobalt-containing cathode material of waste lithium batteries to dibenzothiophene in the model oil is 90:1. After stirring and reacting at 70 °C at a stirring rate of 990 rpm for 240 min, let it stand for stratification. The upper oil phase is the desulfurized model oil.

[0069] Take the upper model oil for detection. The conversion rate of dibenzothiophene is 99.97%; the lower layer is washed with water, filtered, and dried to obtain the mass of the unreacted cobalt lithium oxide black solid. Then, combined with the mass of the cathode material taken before the reaction, the conversion rate of cobalt lithium oxide is calculated to be 50.58%.

[0070] Example 12

[0071] The waste lithium - ion battery cathode material used in the present invention is specifically the ternary material lithium nickel cobalt manganese oxide; dilute sulfuric acid with a mass fraction of 70% is used; a model oil formed by mixing dibenzothiophene and n - hexadecane is used to simulate real diesel, and the initial sulfur content is 1000 ppm.

[0072] Taking the cobalt - containing waste lithium - ion battery cathode material and dilute sulfuric acid in a mass ratio of 1:4, adding them into the model oil, the molar ratio of the cobalt - containing waste lithium - ion battery cathode material to dibenzothiophene in the model oil is 10:1. After stirring and reacting at 70 °C for 30 min at a stirring rate of 990 rpm, it is allowed to stand for stratification, and the upper oil phase is the desulfurized model oil.

[0073] Taking the upper - layer model oil for detection, the conversion rate of dibenzothiophene is 89.44%.

[0074] Figure 3 Figure for comparing liquid chromatography before and after oxidative desulfurization in Example 12. It can be seen that the peak value of dibenzothiophene decreases significantly after the reaction, indicating that most of the sulfides have been removed.

[0075] Example 13

[0076] The waste lithium - ion battery cathode material used in the present invention is specifically the ternary material lithium nickel cobalt manganese oxide; dilute sulfuric acid with a mass fraction of 70% is used; a model oil formed by mixing dibenzothiophene and n - hexadecane is used to simulate real diesel, and the initial sulfur content is 1000 ppm.

[0077] Taking the cobalt - containing waste lithium - ion battery cathode material and dilute sulfuric acid in a mass ratio of 1:4, adding them into the model oil, the molar ratio of the cobalt - containing waste lithium - ion battery cathode material to dibenzothiophene in the model oil is 10:1. After stirring and reacting at 70 °C for 60 min at a stirring rate of 990 rpm, it is allowed to stand for stratification, and the upper oil phase is the desulfurized model oil.

[0078] Taking the upper - layer model oil for detection, the conversion rate of dibenzothiophene is 98.58%.

[0079] Comparative Example 1

[0080] The difference between Comparative Example 1 and Example 1 is only that: dilute sulfuric acid is not added.

[0081] As a result, the conversion rate of dibenzothiophene is only 0.39%.

[0082] The above embodiments are merely examples given for clear illustration and not limitations on the implementation. For those of ordinary skill in the art, based on the above description, other different forms of changes or variations can be made. It is not necessary and impossible to enumerate all implementation manners here, and thus the obvious changes or variations derived therefrom still fall within the protection scope of the present invention.

Claims

1. A method for oxidative desulfurization of cobalt-containing cathode materials from waste lithium batteries, characterized in that, Add the cobalt-containing cathode material of waste lithium batteries and dilute sulfuric acid into the fuel oil. After stirring and reacting, let it stand for stratification. The upper oil phase is the desulfurized fuel oil.

2. The method for oxidative desulfurization using a cobalt-containing cathode material of waste lithium batteries according to claim 1, characterized in that The cobalt-containing cathode material of the waste lithium battery is lithium cobaltate or ternary material; the fuel oil is one of kerosene and diesel.

3. The method for oxidative desulfurization using the cobalt-containing cathode material of waste lithium batteries according to claim 1, characterized in that, The fuel oil contains thiophene sulfides with a content of 100-10,000 ppm. The thiophene sulfides are one or several of dibenzothiophene, benzothiophene, and 4,6-dimethyldibenzothiophene.

4. The method for oxidative desulfurization using a cobalt-containing cathode material of waste lithium batteries according to claim 1, characterized in that, The molar ratio of the cobalt-containing cathode material of the waste lithium battery to the thiophene sulfides in the fuel oil is (10-90):

1.

5. The method for oxidative desulfurization using the cobalt-containing cathode material of waste lithium batteries according to claim 1, characterized in that, When the cobalt-containing cathode material of the waste lithium battery is lithium cobaltate, the molar ratio to the thiophene sulfides in the fuel oil is (50-90):

1.

6. The method for oxidative desulfurization using a cobalt-containing cathode material of waste lithium batteries according to claim 1, characterized in that, When the cobalt-containing cathode material of the waste lithium battery is ternary material, the molar ratio to the thiophene sulfides in the fuel oil is (10-20):

1.

7. The method for oxidative desulfurization using a cobalt-containing cathode material of waste lithium batteries according to claim 1, characterized in that, The stirring speed of the stirring reaction is 600-1000 rpm, the reaction temperature is 50-80 °C, and the reaction time is 30-240 min.

8. The method for oxidative desulfurization using a cobalt-containing cathode material of waste lithium batteries according to claim 1, characterized in that, The stirring speed of the stirring reaction is 900-1000 rpm, the reaction temperature is 70-80 °C, and the reaction time is 120-240 min.

9. The method for oxidative desulfurization using a cobalt-containing cathode material of waste lithium batteries according to claim 1, wherein, The mass fraction of the dilute sulfuric acid is 50-70%; the mass ratio of the cobalt-containing cathode material of the waste lithium battery to the dilute sulfuric acid is 1:(2-4).

10. The method for oxidative desulfurization using a cobalt-containing cathode material of waste lithium batteries according to claim 1, characterized in that, The conversion rate of the method to dibenzothiophene is ≥40%, the conversion rate of benzothiophene is ≥70%, and the conversion rate of 4,6-dimethyldibenzothiophene is ≥40%.

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