A method for preparing lithium sulfide from hydrogen sulfide-containing natural gas

Abstract

This invention belongs to the field of rechargeable battery technology and provides a method for preparing lithium sulfide from hydrogen sulfide-containing natural gas. The basic process involves passing natural gas containing a low concentration of hydrogen sulfide through a reactor equipped with a lithium source. The two react under heating conditions to generate lithium sulfide, while simultaneously removing the hydrogen sulfide from the natural gas, achieving desulfurization. The resulting lithium sulfide product has high purity and small particle size, and can be directly used as a raw material for preparing sulfide solid electrolytes and as a positive electrode active material for lithium-sulfur batteries. This method can be combined with natural gas production processes to effectively absorb hydrogen sulfide from natural gas and convert it into high-value-added lithium sulfide; therefore, this technology has high economic value.

Description

Technical Field

[0001] This invention belongs to the field of rechargeable battery technology, specifically relating to a method for preparing lithium sulfide using hydrogen sulfide-containing natural gas. Background Technology

[0002] Natural gas, shale gas, and other natural gas-containing materials typically contain hydrogen sulfide, an acidic gas that not only corrodes equipment and pipelines but also harms the environment and human health. Therefore, desulfurization and purification are essential before further processing and utilization. Currently, the main industrial desulfurization method is solvent absorption, a chemical process that selectively absorbs hydrogen sulfide from the gas using a specific solvent. Its core lies in utilizing the difference in physical solubility or chemical reaction between the solvent and hydrogen sulfide to continuously remove acidic gases in an absorption-regeneration cycle. Commonly used solvents are generally alkaline, such as MDEA (N-methyldiethanolamine). The solvent contacts the hydrogen sulfide-containing natural gas in an absorption tower, removing the hydrogen sulfide. The solvent after the reaction needs to enter a regeneration tower for heating to release the absorbed hydrogen sulfide gas, and then returns to the absorption tower for reuse.

[0003] Specifically, the chemical reaction using the solvent absorption method of amine solution can be represented by chemical formula (1).

[0004] (1)

[0005] However, solvent absorption methods have several drawbacks, such as high energy consumption during solvent heating and regeneration, high construction costs for absorption and regeneration towers, and the need for additional equipment to treat the hydrogen sulfide gas released during regeneration. For example, Chinese patent CN107376615B discloses a method for removing hydrogen sulfide and other acidic gases from mixed gases such as natural gas and oil refinery gas using a composite amine solvent. This method requires circulating the solvent in an absorption tower, heat exchanger, booster pump, and regeneration tower, placing high demands on the equipment and failing to convert the removed hydrogen sulfide gas into other chemicals. With the increasing energy shortage and stricter environmental regulations, this process is no longer adequate.

[0006] Lithium sulfide is a key raw material for the production of new all-solid-state batteries and lithium-sulfur batteries, and is widely used in the field of secondary energy storage. At present, the main methods for synthesizing lithium sulfide include the carbothermic reduction of lithium sulfate and the solution method. The industrial production method of lithium sulfide is the carbothermic reduction of lithium sulfate. The chemical equation of this reaction is shown in (2). Under standard conditions, it is a thermodynamically non-spontaneous reaction and can only be carried out at high temperatures (700-1000℃). This production method has disadvantages such as low production capacity due to intermittent reaction, high cost due to complex process, high energy consumption due to the need for secondary calcination, and environmental unfriendliness due to the emission of a large amount of greenhouse gas CO2. It is difficult to carry out large-scale production and does not meet the requirements of my country's "dual carbon target".

[0007] Li2SO4 + 2C → Li2S + 2CO2 (2)

[0008] For example, Chinese patent CN1188337782A discloses a method for preparing lithium sulfide by carbothermic reduction of lithium sulfate. This method has complicated steps, requiring the mixing and ball milling of lithium sulfate and organic carbon precursor in a certain ratio to obtain a precursor that can be calcined at high temperature, and then calcining twice to obtain lithium sulfide. The process is complicated.

[0009] The solution method generally refers to the liquid-phase reaction of a lithium-containing compound (or lithium) and a sulfur-containing compound (or sulfur) in an organic solvent to obtain lithium sulfide. The lithium metal or lithium-containing compounds used in this method (such as lithium hydride, lithium triethylborohydride, etc.) are expensive, have poor safety, and are difficult to use as raw materials for large-scale production. For example, Chinese patent CN119176525A discloses a method for synthesizing lithium sulfide using a lithium-containing solution and elemental sulfur as raw materials. This method uses organic ether solutions, which are difficult to remove, have poor safety, are expensive, and are difficult to scale up.

[0010] Current technologies for preparing lithium sulfide using hydrogen sulfide gas as a sulfur source all use pure hydrogen sulfide, resulting in poor reaction safety and high transportation and storage costs. For example, Chinese patent CN113415812B discloses a method for preparing lithium sulfide by reacting substandard lithium amide with pure hydrogen sulfide. This method uses pure hydrogen sulfide gas, leading to high storage and transportation costs and making large-scale production difficult.

[0011] In summary, current methods for synthesizing lithium sulfide still face numerous challenges, hindering its industrialization and keeping its price high. Therefore, exploring cost-effective and environmentally friendly methods for synthesizing lithium sulfide using low-concentration hydrogen sulfide from natural gas containing hydrogen sulfide is of great significance. Summary of the Invention

[0012] The purpose of this invention is to address the shortcomings of existing technologies by providing a method and application for preparing lithium sulfide from low-concentration hydrogen sulfide in hydrogen sulfide-containing natural gas. The reaction product of this method is high-value-added lithium sulfide, which can be used as a cathode material for lithium-sulfur batteries and a raw material for preparing sulfide solid electrolytes. Furthermore, this method can be integrated with the natural gas industry, can completely absorb hydrogen sulfide from hydrogen sulfide-containing natural gas, has a high reaction conversion rate, requires no absorption medium regeneration cycle, has low energy consumption, and low equipment requirements.

[0013] To achieve the above objectives, the present invention adopts the following technical solution:

[0014] This invention relates to a method and application for preparing lithium sulfide from low-concentration hydrogen sulfide in hydrogen sulfide-containing natural gas, comprising the following steps:

[0015] S1: Place the lithium source in the reactor and preheat it to the set temperature.

[0016] S2: Sulfur-containing raw material gas is introduced into the reactor and reacted for a certain period of time;

[0017] S3: Cool the reactor to room temperature under inert gas protection and collect the solid lithium sulfide product.

[0018] Furthermore, the set temperature in step S1 is 200~900℃, and the heating rate is 1~20℃ / min.

[0019] Furthermore, the lithium source mentioned in step S1 includes lithium ion-containing compounds such as lithium oxide, lithium hydroxide, lithium carbonate, lithium nitride, lithium hydroxide monohydrate, and lithium hydride.

[0020] Furthermore, the components of the hydrogen sulfide-containing natural gas mentioned in step S2 include: 1-20% hydrogen sulfide, 70-90% methane, 0-5% carbon dioxide, 0.1-2% short-chain alkanes, 0.1-10% nitrogen, and 0-1% water.

[0021] Furthermore, the reaction conditions described in step S2 include: the rate of hydrogen sulfide introduction is 100~500 sccm, and the molar ratio of S atoms in hydrogen sulfide to Li atoms in the lithium source is 0.5:1~3:1.

[0022] Furthermore, the inert gas mentioned in step S3 includes helium, neon, nitrogen, argon, or krypton.

[0023] Furthermore, short-chain alkanes include at least one alkane that is gaseous at room temperature, such as one or more of methane, ethane, propane, butane, and pentane.

[0024] The second objective of this invention is to provide lithium sulfide prepared by any of the above-described methods.

[0025] The beneficial effects of this invention are as follows:

[0026] (1) The present invention uses hydrogen sulfide in natural gas containing hydrogen sulfide as a sulfur source and reacts it with common and inexpensive lithium sources. While removing hydrogen sulfide, it can also obtain lithium sulfide, a high-value by-product, which has high economic benefits.

[0027] (2) Using hydrogen sulfide as a raw material, the reaction is green and environmentally friendly, which is in line with the concept of green chemistry.

[0028] (3) The conversion rate of lithium atoms in this reaction is high, reaching approximately 100%.

[0029] (4) Compared with other methods for removing hydrogen sulfide (such as solvent absorption), this method does not require regeneration and circulation of the absorption medium, has low energy consumption and low equipment requirements. Attached Figure Description

[0030] Figure 1 This is a flowchart illustrating the preparation of lithium sulfide according to the present invention;

[0031] Figure 2 This is a schematic diagram of an actual apparatus for preparing lithium sulfide according to the present invention;

[0032] Figure 3 The images show the X-ray diffraction (XRD) pattern and scanning electron microscope (SEM) image of lithium sulfide prepared in Example 1 of this invention.

[0033] Figure 4 The XRD and SEM images of lithium sulfide prepared in Example 2 of this invention are shown.

[0034] Figure 5 The images show the XRD and SEM images of lithium sulfide prepared in Example 3 of this invention.

[0035] Among them: 1. Hastelloy tube, 2. Pipe plug, 3. Corundum tube, 4. Lithium source powder, 5. Pipe plug, 6. Flange, 7. Flange; Detailed Implementation

[0036] To make the technical solution and advantages of the present invention clearer, the present invention and its beneficial effects will be described in further detail below with reference to specific embodiments and accompanying drawings. However, the embodiments of the present invention are not limited thereto.

[0037] Example 1

[0038] like Figure 1 As shown, a method for producing lithium sulfide using industrial hydrogen sulfide waste gas includes the following steps:

[0039] S1. Weigh 1.04 g of lithium hydroxide and place it in a reactor, then heat it to 300°C at a heating rate of 5°C / min.

[0040] S2. After the reactor temperature reaches 300℃, the waste gas to be treated (containing 20% ​​hydrogen sulfide, 74.7% methane, 0% carbon dioxide, 0.2% short-chain alkanes, 5% nitrogen, and 0.1% water) is introduced into the reactor at a rate of 100 sccm for 140 minutes. During this process, the sulfur / lithium molar ratio in the sulfur source hydrogen sulfide and the lithium source lithium hydroxide is approximately 3:1. The reaction between lithium hydroxide and hydrogen sulfide in the reactor is as follows:

[0041] 2LiOH + H2S → Li2S + 2H2O

[0042] S3. Under the protection of argon atmosphere, after cooling, the solid obtained from the reaction is taken out from the reactor and 0.91 g of lithium sulfide product is collected.

[0043] Figure 3 These are the XRD and SEM images of the lithium sulfide sample prepared in this example.

[0044] Example 2

[0045] like Figure 1 As shown, a method for producing lithium sulfide using industrial hydrogen sulfide waste gas includes the following steps:

[0046] S1. Weigh 1.61 g of lithium carbonate and place it in a reactor, and heat it to 800°C at a heating rate of 10°C / min.

[0047] S2. After the reactor temperature reaches 800℃, the waste gas to be treated (containing 12% hydrogen sulfide, 72% methane, 5% carbon dioxide, 0.1% short-chain alkanes, 10% nitrogen, and 1% water) is introduced into the reactor at a rate of 200 sccm for 100 minutes. During this process, the sulfur / lithium molar ratio in the sulfur source hydrogen sulfide and the lithium source lithium carbonate is approximately 2:1. The reaction between lithium carbonate and hydrogen sulfide in the reactor is as follows:

[0048] Li2CO3 + H2S → Li2S + H2O + CO2

[0049] S3. Under the protection of argon atmosphere, after cooling, the solid obtained from the reaction was taken out from the reactor and 0.88 g of lithium sulfide was collected.

[0050] Figure 4 These are the XRD and SEM images of the lithium sulfide sample prepared in this example.

[0051] Example 3

[0052] like Figure 1 As shown, a method for producing lithium sulfide using industrial hydrogen sulfide waste gas includes the following steps:

[0053] S1. Weigh 0.52 g of lithium nitride and place it in the reactor, and heat it to 500°C at a heating rate of 3°C / min.

[0054] S2. After the reactor temperature reaches 500℃, the waste gas to be treated (containing 5% hydrogen sulfide, 87% methane, 1% carbon dioxide, 2% short-chain alkanes, 5% nitrogen, and 0% water) is introduced into the reactor at a rate of 500 sccm for 20 minutes. During this process, the sulfur / lithium molar ratio in the sulfur source hydrogen sulfide and the lithium source lithium nitride is approximately 0.5:1. The reaction between lithium nitride and hydrogen sulfide in the reactor is as follows:

[0055] 2Li3N + 3H2S → 3Li2S + 2NH3

[0056] S3. Under the protection of argon atmosphere, after cooling, the solid obtained from the reaction was taken out from the reactor and 0.94 g of lithium sulfide was collected.

[0057] Figure 5 These are the XRD and SEM images of the lithium sulfide sample prepared in this example.

[0058] Compared with existing technologies, the preparation method provided by this invention can convert inexpensive lithium sources such as lithium compounds into high-value-added products such as lithium sulfide, resulting in high economic benefits. On the other hand, the method has a high reaction conversion rate and a desulfurization rate of nearly 100%, while eliminating the need for absorption medium regeneration and recycling, resulting in low energy consumption and low equipment requirements.

[0059] Based on the disclosure and guidance of the foregoing specification, those skilled in the art can make changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments described above, and any obvious improvements, substitutions, or modifications made by those skilled in the art based on the present invention are within the scope of protection of the present invention. Furthermore, although some specific terms are used in this specification, these terms are only for convenience of explanation and do not constitute any limitation on the present invention.

Claims

1. A method for preparing lithium sulfide from hydrogen sulfide-containing natural gas, characterized in that, Includes the following steps: S1: Place the lithium source in the reactor and preheat it to the set temperature; S2: Sulfur-containing raw material gas is introduced into the reactor and reacted for a certain period of time; S3: Cool the reactor to room temperature under inert gas protection and collect the solid lithium sulfide product.

2. The method for preparing lithium sulfide from hydrogen sulfide-containing natural gas according to claim 1, characterized in that, The set temperature in step S1 is 200~900℃, and the heating rate is 1~20℃ / min.

3. The method for preparing lithium sulfide from hydrogen sulfide-containing natural gas according to claim 1, characterized in that, The lithium source mentioned in step S1 includes lithium oxide, lithium hydroxide, lithium carbonate, lithium nitride, lithium hydroxide monohydrate, lithium hydride, and other lithium-ion compounds.

4. The method for preparing lithium sulfide from hydrogen sulfide-containing natural gas according to claim 1, characterized in that, The components of the hydrogen sulfide-containing natural gas mentioned in step S2 include: 1-20% hydrogen sulfide, 70-90% methane, 0-5% carbon dioxide, 0.1-2% short-chain alkanes, 0.1-10% nitrogen, and 0-1% water.

5. A method for preparing lithium sulfide from hydrogen sulfide-containing natural gas according to claim 1, characterized in that, The reaction conditions described in step S2 include: a hydrogen sulfide introduction rate of 100-500 sccm, and a molar ratio of S atoms in hydrogen sulfide to Li atoms in the lithium source of 0.5:1 to 3:

1.

6. The method for preparing lithium sulfide from hydrogen sulfide-containing natural gas according to claim 1, characterized in that, The inert gas mentioned in step S3 includes helium, neon, nitrogen, argon, or krypton.

7. The method for preparing lithium sulfide from hydrogen sulfide-containing natural gas according to claim 1, characterized in that, The short-chain alkanes include at least one alkane that is gaseous at room temperature, such as one or more of methane, ethane, propane, butane, and pentane.

8. A lithium sulfide material, characterized in that, Lithium sulfide obtained by any one of the preparation methods described in claims 1-7.

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