阅读说明：本技术 用于制备双(氟磺酰基)酰亚胺的方法 (Process for preparing bis (fluorosulfonyl) imide ) 是由 D.德里-伯特 于 2020-04-21 设计创作，主要内容包括：本发明涉及用于制备双(氟磺酰基)酰亚胺的方法,该方法包括以下步骤：i)提供含有HF的物流A1和含有液相A2的反应器,该液相A2含有双(氯磺酰基)酰亚胺；ii)在所述反应器中,使所述液相A2与所述物流A1接触,以产生双(氟磺酰基)酰亚胺,所述方法的特征在于将所述物流A1注射到所述液相A2中。(The present invention relates to a process for the preparation of a bis (fluorosulfonyl) imide, said process comprising the steps of: i) providing a stream a1 comprising HF and a reactor comprising a liquid phase a2, the liquid phase a2 comprising bis (chlorosulfonyl) imide; ii) contacting, in the reactor, the liquid phase a2 with the stream a1 to produce bis (fluorosulfonyl) imide, characterized in that the stream a1 is injected into the liquid phase a 2.)

1. A process for preparing a bis (fluorosulfonyl) imide, comprising the steps of:

i) providing a stream a1 comprising HF, and providing a reactor containing a liquid phase a2, the liquid phase a2 comprising a bis (halosulfonyl) imide;

ii) contacting said liquid phase a2 with said stream a1 in said reactor to produce a bis (fluorosulfonyl) imide;

characterized in that the stream A1 is injected into the liquid phase A2.

2. The process according to the preceding claim, characterized in that said reactor comprises means for mechanical stirring of said liquid phase A2.

3. The process according to any one of the preceding claims, characterized in that step ii) is carried out under pressure and temperature conditions such that the bis (halosulfonyl) imide and the bis (fluorosulfonyl) imide produced are maintained in liquid form.

4. The method according to any of the preceding claims, wherein the temperature of the liquid phase a2 remains substantially unchanged during step ii).

5. The process according to any of the preceding claims, wherein during step ii) the temperature of the liquid phase a2 varies by at most 5 ℃ in absolute terms, preferably by at most 3 ℃ in absolute terms, still more preferably by at most 2 ℃ in absolute terms, or in particular by at most 1 ℃ in absolute terms.

6. The process according to any of the preceding claims, characterized in that the reactor further comprises a dip tube through which the stream a1 is injected into the liquid phase a 2.

7. The process according to any of the preceding claims, characterized in that the reactor comprises mechanical stirring means of the liquid phase a2, and the stream a1 is injected into the liquid phase a2 close to the mechanical stirring means.

8. The process according to any one of the preceding claims, characterized in that the hydrofluoric acid contained in the stream a1 is introduced into the liquid phase a2 at a rate of at least 1mol HF per mole of bis (halosulfonyl) imide per hour and preferably at most 100mol HF per mole of bis (halosulfonyl) imide per hour.

9. The process according to any of the preceding claims, characterized in that step ii) is carried out with a HF/[ bis (halosulfonyl) imide ] molar ratio of at least 2.0 and at most 3.0.

10. The process according to any of the preceding claims, characterized in that step ii) is carried out at a temperature above 0 ℃.

11. A method according to any preceding claim, wherein the bis (halosulfonyl) imide compound is bis (chlorosulfonyl) imide.

12. A process for preparing a lithium bis (fluorosulfonyl) imide salt, comprising the steps of:

a) carrying out the process for the preparation of bis (fluorosulfonyl) imide according to any one of the preceding claims 1-11;

b) contacting a bis (fluorosulfonyl) imide with a composition comprising at least one lithium salt to form the lithium bis (fluorosulfonyl) imide salt.

Technical Field

The present invention relates to a process for the preparation of bis (fluorosulfonyl) imide. In particular, the present invention relates to a process for preparing a bis (fluorosulfonyl) imide from a bis (halosulfonyl) imide.

Background

Since the sulfonyl imide type anions are very low in basicity, they are increasingly used in the field of energy storage in the form of inorganic salts in batteries or in the form of organic salts in supercapacitors or in the field of ionic liquids. Since the rapid development of the battery market and the reduction of the manufacturing cost of the battery are becoming important issues, large-scale, low-cost synthesis methods of this type of anion are required.

In the particular field of Li-ion batteries, the most widely used salt at present is LiPF₆However, this salt has many disadvantages such as limited thermal stability, sensitivity to hydrolysis and thus reduced battery safety. Recently, studies have been made with FSO₂ ^–Novel salts of the groups and which exhibit a number of advantages such as better ion conductivity and hydrolysis resistance. One of these salts, LiFSI (LiN (FSO)₂)₂) Exhibit highly beneficial properties that make it a replacement for LiPF₆Good alternatives of (4).

There are different methods of preparing LiFSI. WO2009/123328 describes in particular the preparation of LiFSI from bis (chlorosulfonyl) imide via steps of preparing intermediate salts, such as bis (fluorosulfonyl) imide zinc salt, followed by bis (fluorosulfonyl) imide ammonium salt.

For obtaining LiFSI, one of the reaction intermediates is bis (fluorosulfonyl) imide. WO2015/012897 describes the preparation of bis (fluorosulfonyl) imides by fluorination of bis (halosulfonyl) in the presence of hydrofluoric acid. The preparation of bis (fluorosulfonyl) imide (HFSI) was obtained under hydrofluoric acid reflux conditions. Carrying out the process under these conditions may promote the formation of unwanted by-products. Furthermore, the operating conditions applied in the process require significant energy input, which increases the carbon footprint of the process.

Therefore, there remains a need for a process for preparing bis (fluorosulfonyl) imides that does not have the above-mentioned disadvantages.

Disclosure of Invention

According to a first aspect, the present invention provides a process for the preparation of a bis (fluorosulfonyl) imide, comprising the steps of:

i) providing a stream a1 comprising HF, and providing a reactor containing a liquid phase a2, the liquid phase a2 comprising a bis (halosulfonyl) imide;

ii) contacting said liquid phase A2 with said stream A1 in said reactor to produce a bis (fluorosulfonyl) imide

Characterized in that the stream A1 is injected into the liquid phase A2.

Preferably, the reactor comprises mechanical stirring means of the liquid phase a 2. The term "mechanical stirring means" is understood to mean a stirring means which does not use magnetic means, such as magnetic stirring rods, inside the reactor.

The invention makes it possible to ensure the uniformity of the hydrofluoric acid concentration at any point of the reactor, thus avoiding regions of higher stable concentration of HF in the reaction medium, which would lead to a significant increase in the formation of unwanted by-products and therefore to a significant reduction in the yield of bis (fluorosulfonyl) imide. The invention also makes it possible to ensure the uniformity of the temperature at any point of the reaction medium and to avoid obtaining hot zones (hot spots) in the reactor, which also promote the degradation reactions.

In order to control the stable concentration of HF, the stream a1 is preferably continuously injected into the liquid phase a 2.

According to a preferred embodiment, step ii) is carried out under pressure and temperature conditions such that the bis (halosulfonyl) imide and the bis (fluorosulfonyl) imide produced are maintained in liquid form.

According to a preferred embodiment, the temperature of the liquid phase a2 remains substantially unchanged during step ii).

According to a preferred embodiment, during step ii), the temperature of the liquid phase a2 varies by at most 5 ℃ in absolute terms, preferably by at most 3 ℃ in absolute terms, still more preferably by at most 2 ℃ in absolute terms, or in particular by at most 1 ℃ in absolute terms.

According to a preferred embodiment, the reactor further comprises a dip tube (dip tube) through which the stream a1 is injected into the liquid phase a 2.

According to a preferred embodiment, the reactor comprises mechanical stirring means of the liquid phase a2, and the stream a1 is injected into the liquid phase a2 close to the mechanical stirring means.

According to a preferred embodiment, the hydrofluoric acid contained in said stream a1 is introduced into said liquid phase a2 at a rate of at least 1mol HF per mole of bis (halosulfonyl) imide per hour and preferably at most 100mol HF per mole of bis (halosulfonyl) imide per hour.

According to a preferred embodiment, step ii) is carried out with a HF/[ bis (halosulfonyl) imide ] molar ratio of at least 2.0 and at most 3.0.

According to a preferred embodiment, step ii) is carried out at a temperature above 0 ℃.

According to a preferred embodiment, the bis (halosulfonyl) imide compound is bis (chlorosulfonyl) imide.

According to another aspect, the present invention provides a method for preparing a lithium bis (fluorosulfonyl) imide salt, comprising the steps of:

a) carrying out the process for the preparation of bis (fluorosulfonyl) imide according to the present invention;

b) contacting a bis (fluorosulfonyl) imide with a composition comprising at least one lithium salt to form the lithium bis (fluorosulfonyl) imide salt.

Drawings

FIG. 1 schematically represents a reactor for carrying out a process for the preparation of bis (fluorosulfonyl) imide according to one particular embodiment.

FIG. 2 schematically shows a simplified cross-sectional view of a reactor for carrying out a process for preparing a bis (fluorosulfonyl) imide, according to one particular embodiment.

Detailed Description

According to a first aspect, the present invention provides a process for the preparation of a bis (fluorosulfonyl) imide. Preferably, the method comprises the steps of:

i) providing a stream a1 comprising HF, and providing a reactor containing a liquid phase a2, the liquid phase a2 comprising a bis (halosulfonyl) imide;

ii) contacting said liquid phase a2 with said stream a1 in said reactor to produce a bis (fluorosulfonyl) imide.

In the present process, the stream a1 may be a gas stream or a liquid stream. Thus, in said stream a1, the hydrofluoric acid may be in gaseous form or in liquid form.

According to a particular embodiment, the liquid phase a2 comprises bis (halosulfonyl) imide but no organic solvent. Thus, the step ii) of fluorinating the bis (halosulfonyl) imide to the bis (fluorosulfonyl) imide is carried out in the absence of an organic solvent.

According to an alternative specific embodiment, the liquid phase a2 comprises a bis (halosulfonyl) imide and an organic solvent. The organic solvent SO1 may be selected from esters, nitriles, ethers, aromatic solvents, carbonates, cyclic or heterocyclic type solvents and mixtures thereof. Preferably, the organic solvent SO1 is selected from the group consisting of methyl acetate, butyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, butyronitrile, valeronitrile, benzonitrile, diisopropyl ether, 2-methoxy-2-methylbutane, cyclopentylmethyl ether, benzene, toluene, chlorobenzene, dichlorobenzene, xylene, ethylbenzene, 1, 4-dioxane, dimethyl carbonate, ethylene carbonate, sulfolane and mixtures thereof.

Preferably, the hydrofluoric acid is anhydrous hydrofluoric acid. In the context of the present invention, the term "anhydrous hydrofluoric acid" is understood to mean HF containing less than 500ppm of water, preferably less than 300ppm of water and preferably less than 200ppm of water.

Preferably, the reactor comprises mechanical stirring means. Preferably, the mechanical stirring tool is a rotary mechanical stirring tool. The mechanical stirring means comprises an electric motor (motor) which imparts a rotational motion to a stirring element mixing the liquid phase a2 through a shaft. The stirring element may have various shapes. For example, the stirring element may be of the propeller (propeller) type, blade turbine (bladed turbine) type or anchor (anchor) type.

The stirring element may be of the propeller type and comprise at least two blades, preferably 2, 3, 4, 5, 6, 7 or 8 blades. In this case, the stirring element causes a substantially axial movement with low shear. The diameter of the stirring element is for example 1/5-2/3 of the diameter of the reactor. Such a ratio between the diameter of the stirring element and the diameter of the reactor makes it possible to promote axial stirring and thus homogenization and heat transfer. The pitch (pitch) of the stirring blade is preferably 0.5 to 3 times the diameter of the stirring element, in particular the pitch is equal to the diameter of the stirring element. Pitch here refers to the theoretical distance the propeller has travelled during one complete 360 deg. rotation. In this configuration, the blades of the stirring element may be arranged perpendicularly to the axis or in an inclined manner with respect to the axis.

The stirring element may be of the bladed turbine type. In such a configuration, the stirring element comprises a horizontal disc on which two or more blades, in particular 4-8 blades, are arranged. In such a configuration, the stirring element induces a substantially radial flow. The diameter of the stirring element is for example 1/5-2/3 of the diameter of the reactor. The vanes may be flat or curved in shape. The blades are arranged generally perpendicular to the horizontal disc.

The stirring element may be of the anchor type. This stirring element then consists of a U-shaped tube or a flat strip rotating in a radial plane close to the wall of the reactor.

The presence of the rotating mechanical stirring means enables a good homogeneity of concentration and temperature at any point of the reactor. In particular, the rotating mechanical stirring means promotes heat transfer with the reactor wall.

Preferably, the stream a1 is injected into the liquid phase a 2. The term "injection" means the direct introduction of stream a1 into the liquid phase a 2. Thereby reacting hydrofluoric acid with the bis (halosulfonyl) imide to form the bis (fluorosulfonyl) imide. The bis (halosulfonyl) imide may be bis (chlorosulfonyl) imide, bis (bromosulfonyl) imide, or bis (iodosulfonyl) imide, or a mixture thereof. Preferably, in the present application, the bis (halosulfonyl) imide is bis (chlorosulfonyl) imide. In particular, the stream a1 was continuously injected into the liquid phase a 2.

Furthermore, the implementation of step ii) results in the formation of a compound of formula HX, wherein X is Cl, Br or I. The compound of formula HX produced is preferably in gaseous form under the operating conditions of the process, i.e. under the temperature and pressure conditions used in the process, in particular in step ii). The compound of formula HX can be degassed from the reaction medium, for example by stripping with an inert gas such as nitrogen, helium or argon. Preferably, the compound HX is continuously removed during the implementation of step ii). Preferably, when the bis (halosulfonyl) imide is bis (chlorosulfonyl) imide, compound HX is HCl. When the bis (halosulfonyl) imide is bis (bromosulfonyl) imide, compound HX is HBr. When the bis (halosulfonyl) imide is bis (iodosulfonyl) imide, compound HX is HI.

Preferably, step ii) is carried out under pressure and temperature conditions such that the bis (halosulfonyl) imide and the resulting bis (fluorosulfonyl) imide are maintained in liquid form.

Thus, step ii) may be carried out at atmospheric pressure or at a pressure higher than atmospheric pressure. Preferably, step ii) may be carried out at a pressure of less than 10bara, advantageously less than 9bara, preferably less than 8bara, more preferably less than 7bara, especially less than 6 bara.

Step ii) may be carried out at a temperature above 0 ℃, advantageously above 5 ℃, preferably above 10 ℃, more preferably above 15 ℃.

Preferably, step ii) can be carried out at a temperature below 150 ℃, advantageously below 140 ℃, preferably below 130 ℃, more preferably below 120 ℃, in particular below 110 ℃, more particularly below 100 ℃, advantageously below 90 ℃, advantageously below 80 ℃, preferably advantageously below 70 ℃, more preferably advantageously below 60 ℃, particularly advantageously below 50 ℃.

Thus, step ii) may be carried out as follows: at a temperature above 0 ℃, advantageously above 5 ℃, preferably above 10 ℃, more preferably above 15 ℃; and at a temperature below 150 ℃, advantageously below 140 ℃, preferably below 130 ℃, more preferably below 120 ℃, in particular below 110 ℃, more particularly below 100 ℃, advantageously below 90 ℃, advantageously below 80 ℃, preferably advantageously below 70 ℃, more preferably advantageously below 60 ℃, particularly advantageously below 50 ℃.

Preferably, step ii) may be carried out as follows: at a temperature above 0 ℃, advantageously above 5 ℃, preferably above 10 ℃, more preferably above 15 ℃; and at a temperature below 150 ℃, beneficially below 140 ℃, preferably below 130 ℃, more preferably below 120 ℃, in particular below 110 ℃, more particularly below 100 ℃, advantageously below 90 ℃, beneficially below 80 ℃, preferably advantageously below 70 ℃, more preferably advantageously below 60 ℃, particularly advantageously below 50 ℃; and at atmospheric pressure.

Preferably, step ii) may be carried out as follows: at a temperature above 0 ℃, advantageously above 5 ℃, preferably above 10 ℃, more preferably above 15 ℃; and at a temperature below 150 ℃, beneficially below 140 ℃, preferably below 130 ℃, more preferably below 120 ℃, in particular below 110 ℃, more particularly below 100 ℃, advantageously below 90 ℃, beneficially below 80 ℃, preferably advantageously below 70 ℃, more preferably advantageously below 60 ℃, particularly advantageously below 50 ℃; and at a pressure above 1 bara; and below 10bara, advantageously at a pressure below 9bara, preferably below 8bara, more preferably below 7bara, in particular below 6 bara.

Preferably, the temperature of the liquid phase a2 remains substantially unchanged during step ii). In the present application, the term "substantially unchanged" is understood to mean that the temperature variation is at most 5 ℃ in absolute terms, preferably at most 3 ℃ in absolute terms, still more preferably at most 2 ℃ in absolute terms, or in particular at most 1 ℃ in absolute terms.

Thus, during step ii), the temperature of the liquid phase a2 varies by at most 5 ℃ in absolute terms, preferably by at most 3 ℃ in absolute terms, still more preferably by at most 2 ℃ in absolute terms, or in particular by at most 1 ℃ in absolute terms.

Such small changes in temperature are made possible by: the stream a1 is injected, preferably continuously, directly into the liquid phase a2, and in particular when said stream a1 is injected, preferably continuously, close to the stirring element, as explained below. This low temperature gradient of the liquid phase makes it possible to minimize or even eliminate the formation of impurities (for example FSO)₃H or FSO₂NH₂) Side reactions of (2).

Preferably, in step ii), the hydrofluoric acid contained in the stream a1 is introduced into the liquid phase a2 at a rate of at least 1mol HF/mol bis (halosulfonyl) imide/hour, advantageously at least 5mol HF/mol bis (halosulfonyl) imide/hour, preferably at least 10mol HF/mol bis (halosulfonyl) imide/hour, more preferably at least 20mol HF/mol bis (halosulfonyl) imide/hour, in particular at least 30mol HF/mol bis (halosulfonyl) imide/hour, more in particular at least 40mol HF/mol bis (halosulfonyl) imide/hour, advantageously at least 50mol HF/mol bis (halosulfonyl) imide/hour.

In particular, in step ii), the hydrofluoric acid contained in the stream a1 is introduced into the liquid phase a2 at a rate of at most 130mol HF per mole of bis (halosulfonyl) imide per hour, advantageously at most 120mol HF per mole of bis (halosulfonyl) imide per hour, preferably at most 110mol HF per mole of bis (halosulfonyl) imide per hour, in particular at most 100mol HF per mole of bis (halosulfonyl) imide per hour.

Thus, in step ii), the hydrofluoric acid contained in the stream a1 is introduced into the liquid phase a2 at a rate of at least 1mol HF/mol bis (halosulfonyl) imide/hour, advantageously at least 5mol HF/mol bis (halosulfonyl) imide/hour, preferably at least 10mol HF/mol bis (halosulfonyl) imide/hour, more preferably at least 20mol HF/mol bis (halosulfonyl) imide/hour, in particular at least 30mol HF/mol bis (halosulfonyl) imide/hour, more in particular at least 40mol HF/mol bis (halosulfonyl) imide/hour, advantageously at least 50mol HF/mol bis (halosulfonyl) imide/hour; and at most 130mol HF per mole of bis (halosulfonyl) imide per hour, advantageously at most 120mol HF per mole of bis (halosulfonyl) imide per hour, preferably at most 110mol HF per mole of bis (halosulfonyl) imide per hour, in particular at most 100mol HF per mole of bis (halosulfonyl) imide per hour.

In particular, in step ii), the hydrofluoric acid contained in the stream a1 is introduced into the liquid phase a2 at a rate of at least 1mol HF/mol bis (chlorosulfonyl) imide/hour, advantageously at least 5mol HF/mol bis (chlorosulfonyl) imide/hour, preferably at least 10mol HF/mol bis (chlorosulfonyl) imide/hour, more preferably at least 20mol HF/mol bis (chlorosulfonyl) imide/hour, in particular at least 30mol HF/mol bis (chlorosulfonyl) imide/hour, more in particular at least 40mol HF/mol bis (chlorosulfonyl) imide/hour, advantageously at least 50mol HF/mol bis (chlorosulfonyl) imide/hour.

More particularly, in step ii), the hydrofluoric acid contained in the stream a1 is introduced into the liquid phase a2 at a rate of at most 130mol HF per mole of bis (chlorosulfonyl) imide per hour, advantageously at most 120mol HF per mole of bis (chlorosulfonyl) imide per hour, preferably at most 110mol HF per mole of bis (chlorosulfonyl) imide per hour, in particular at most 100mol HF per mole of bis (chlorosulfonyl) imide per hour.

Thus, in step ii), the hydrofluoric acid contained in the stream a1 is introduced into the liquid phase a2 at a rate of at least 1mol HF/mol bis (chlorosulfonyl) imide/hour, advantageously at least 5mol HF/mol bis (chlorosulfonyl) imide/hour, preferably at least 10mol HF/mol bis (chlorosulfonyl) imide/hour, more preferably at least 20mol HF/mol bis (chlorosulfonyl) imide/hour, in particular at least 30mol HF/mol bis (chlorosulfonyl) imide/hour, more in particular at least 40mol HF/mol bis (chlorosulfonyl) imide/hour, advantageously at least 50mol HF/mol bis (chlorosulfonyl) imide/hour; and at most 130mol HF per mole bis (chlorosulfonyl) imide per hour, advantageously at most 120mol HF per mole bis (chlorosulfonyl) imide per hour, preferably at most 110mol HF per mole bis (chlorosulfonyl) imide per hour, in particular at most 100mol HF per mole bis (chlorosulfonyl) imide per hour.

The rate of introduction of the hydrofluoric acid mentioned above makes it possible to avoid the loss of HF, especially when the latter is introduced in gaseous form. This thus makes it possible to improve the overall efficiency of the process.

Furthermore, the rate of introduction of HF can be controlled such that a low stable concentration of HF is maintained in the reaction medium (i.e. in the liquid phase a 2). Subsequently, HF will be consumed immediately in the fluorination reaction and the molar ratio between HF and bis (halosulfonyl) imide will be close to stoichiometric. The present method makes it possible to limit the use of excess HF. This represents an important economic advantage; the cost of the HF demand will be close to the cost of the theoretical HF demand required for the stoichiometry of the reaction.

Thus, according to a preferred embodiment, step ii) is carried out with a HF/[ bis (halosulfonyl) imide ] molar ratio of at least 2.0, preferably at least 2.05, in particular at least 2.1. Preferably, step ii) is carried out with a molar ratio HF/[ bis (halosulfonyl) imide ] of at most 3.1, preferably at most 3.0, in particular at most 2.9.

Thus, step ii) is carried out with an HF/[ bis (halosulfonyl) imide ] molar ratio of at least 2.0, preferably at least 2.05, in particular at least 2.1 and at most 3.1, preferably at most 3.0, in particular at most 2.9.

Preferably, step ii) is carried out with a HF/[ bis (chlorosulfonyl) imide ] molar ratio of at least 2.0, preferably at least 2.05, in particular at least 2.1. Preferably, step ii) is carried out with a HF/[ bis (chlorosulfonyl) imide ] molar ratio of at most 3.1, preferably at most 3.0, in particular at most 2.9.

Thus, step ii) is carried out with a HF/[ bis (chlorosulfonyl) imide ] molar ratio of at least 2.0, preferably at least 2.05, in particular at least 2.1 and at most 3.1, preferably at most 3.0, in particular at most 2.9.

According to a preferred embodiment, the reactor comprises a dip tube. This makes it possible to inject the stream a1 directly into the liquid phase a 2. Thus one end E1 of the dip tube was placed in the liquid phase a 2. Preferably, the dip tube is located proximate to the mechanical stirring means. As explained in detail above, the mechanical stirring tool, which is preferably of the rotary type, comprises a stirring element. The dip tube is thus positioned close to the stirring element. More particularly, the end E1 of the dip tube placed in the liquid phase a2 is located close to the mechanical stirring means, preferably close to the stirring element. This makes it possible to improve the diffusion of the stream a1 within the liquid phase a 2. Such an arrangement between the dip tube and the stirring element ensures perfect temperature and concentration uniformity within said liquid phase a 2. Thus, the largest dimension of the stirring element through its center "C" is denoted as "D". According to a particular embodiment, the shortest distance between the end E1 of the dip tube placed in the liquid phase a2 and the centre of the stirring element (denoted D1) is less than 2 x D. The centre "C" of the stirring element is generally located on the central axis of said shaft of the mechanical stirring tool (fig. 2).

Thus, according to a particular embodiment, the method comprises the steps of:

i) providing a stream a1 comprising HF, and providing a reactor containing a liquid phase a2, the liquid phase a2 comprising a bis (halosulfonyl) imide; said reactor comprising a dip tube, one end E1 of which is placed in said liquid phase a2, and a mechanical stirring tool comprising stirring elements placed in said liquid phase a 2;

ii) contacting said liquid phase A2 with said stream A1 in said reactor to produce a bis (fluorosulfonyl) imide

Characterized in that the stream a1 is injected into the liquid phase a2 through the dip tube and the distance D1 between the end E1 of the dip tube and the center C of the stirring element is less than 2 x D; wherein D represents the maximum dimension of the stirring element through its center C.

Preferably, the reactor may comprise a jacket. This makes it possible to ensure uniform heating of the reactor and to ensure heat exchange with said liquid phase a 2.

Step ii) is preferably carried out in the absence of a catalyst. This makes it possible to obtain very high yields as described below, while avoiding the implementation of a subsequent step of purification of the bis (fluorosulfonyl) imide to remove all traces of the catalyst.

As specified in the present application, hydrofluoric acid will react with the bis (halosulfonyl) imide during step ii) to form the bis (fluorosulfonyl) imide. Thus, during the performance of the process, the liquid phase a2 will become concentrated in terms of bis (fluorosulfonyl) imide. The weight content of bis (fluorosulfonyl) imide in the liquid phase a2 will gradually increase, while conversely the weight content of bis (halosulfonyl) imide in the liquid phase a2 will gradually decrease. The process is carried out until the desired conversion or selectivity is obtained.

The present process achieves a conversion of the bis (halosulfonyl) imide, preferably bis (chlorosulfonyl) imide, of at least 95%, advantageously at least 96%, preferably at least 97%, more preferably at least 98%, in particular at least 99%, more in particular at least 99.2%, advantageously at least 99.5%, preferably advantageously at least 99.8%, particularly advantageously 100%.

The present process makes it possible to obtain a yield of bis (fluorosulfonyl) imide of at least 80%, advantageously at least 85%, preferably at least 90%, more preferably at least 95%.

The invention may also comprise a step iii) of degassing or stripping the reactor in the presence of an inert gas. The inert gas is preferably nitrogen. This step makes it possible to remove the HCl possibly dissolved in the liquid phase a2 and to remove the unreacted HF.

Preferably, the process comprises a step iv) of recovering the bis (fluorosulfonyl) imide and optionally purifying the latter.

FIG. 1 schematically illustrates a reactor 1 for carrying out the process for producing bis (fluorosulfonyl) imide. The reactor 1 comprises a jacket 11, a dip tube 7 and a rotating mechanical stirring means 6. The rotary mechanical stirring tool 6 comprises a motor 10, a shaft 9 and a rotating element 8. The reactor also contains a liquid phase 2 introduced into the reactor via line 2 a. This liquid phase 2 is introduced into the reactor before the fluorination reaction is carried out. The liquid phase comprises bis (chlorosulfonyl) imide. Hydrofluoric acid 3 is introduced into the reactor via a dip tube 7. As shown in fig. 1, hydrofluoric acid 3 is injected into the liquid phase 2 through a dip tube having one end in the liquid phase 2. Furthermore, as shown in fig. 2, the end E1 of a dip tube through which HF is injected into the liquid phase is located close to the spinner 8. The distance D1 between the end E1 of the dip tube 7 and the center C of the stirring element 8, which represents the maximum dimension of the stirring element 8 through its center C (fig. 2), is less than 2 times the distance D. Hydrochloric acid formed during the reaction is continuously removed via valve 12 and recovered in 4 for subsequent treatment or purification. At the end of the reaction, reactor 1, the liquid phase 2 of which comprises bis (fluorosulfonyl) imide, may be emptied and liquid phase 2 recovered in 5 for subsequent processing, such as purification, or carrying out the process for preparing lithium bis (fluorosulfonyl) imide salt as described below.

According to a second aspect, the present invention relates to a process for preparing a lithium bis (fluorosulfonyl) imide salt.

Preferably, the method comprises the steps of:

a) carrying out the process for the preparation of bis (fluorosulfonyl) imide according to the present invention;

b) contacting a bis (fluorosulfonyl) imide with a composition comprising at least one lithium salt to form a composition comprising the lithium salt of bis (fluorosulfonyl) imide.

According to a preferred embodiment, the composition comprising at least one lithium salt is an aqueous composition, preferably an aqueous suspension or an aqueous solution.

According to another preferred embodiment, the composition comprising at least one lithium salt is a solid composition, preferably a composition consisting of at least one solid lithium salt.

In particular, the bis (fluorosulfonyl) imide is added to a container that includes a composition comprising at least one lithium salt. The vessel may be a reactor, which preferably comprises at least one stirring system. The elements into which the composition obtained in step b) can be incorporated are preferably resistant to HF.

According to one embodiment, the lithium salt is selected from LiOH, LiOH H₂O、LiHCO₃、Li₂CO₃LiCl and mixtures thereof. Preferably, the lithium salt is Li₂CO₃。

When the composition is an aqueous composition comprising at least one lithium salt, the composition may be prepared by any conventional method for preparing alkaline aqueous compositions. It may be, for example, dissolving the lithium salt in ultrapure or deionized water with stirring.

To determine the amount of lithium salt to be incorporated, an analysis of the total acidity of the mixture to be neutralized may typically be performed.

According to one embodiment, step c) is such that:

-the molar ratio of lithium salt divided by the number of basicities of the lithium salt relative to the bis (fluorosulfonyl) imide is greater than or equal to 1, preferably less than 5, preferably less than 3, preferably from 1 to 2; and/or

-the weight ratio of lithium salt to water in the aqueous composition is from 0.1 to 2, preferably from 0.2 to 1, preferably from 0.3 to 0.7.

For example, Li₂CO₃The salt has a base number equal to 2.

Step b) of the process according to the invention can be carried out at a temperature lower than or equal to 40 ℃, preferably lower than or equal to 30 ℃, preferably lower than or equal to 20 ℃ and in particular lower than or equal to 15 ℃.

According to one embodiment, the process according to the invention comprises an additional step of filtering the composition B obtained in step B), obtaining a filtrate F and a filter cake G. A lithium bis (fluorosulfonyl) imide salt may be included in the filtrate F and/or in the filter cake G. The filtrate F may be subjected to at least one extraction step with an organic solvent S, typically sparingly soluble in water, to extract the lithium bis (fluorosulfonyl) imide salt into an organic phase. The extraction step typically results in separation of an aqueous phase and an organic phase. In the context of the present invention, and unless otherwise specified, the term "sparingly water-soluble" is intended to mean a solvent having a solubility in water of less than 5% by weight. The organic solvents S mentioned hereinbefore are in particular selected from the following classes (family): esters, nitriles, ethers, chlorinated and aromatic solvents, and mixtures thereof. Preferably, the organic solvent S is selected from the group consisting of dichloromethane, ethyl acetate, butyl acetate, tetrahydrofuran, diethyl ether and valeronitrile, and mixtures thereof. In particular, the organic solvent S is butyl acetate. For each extraction, the amount of organic solvent used may be 1/6-1 times the weight of filtrate F. The number of extraction times may be 2-10. Preferably, the organic phase resulting from the extraction has a content by weight of lithium bis (fluorosulfonyl) imide salt ranging from 5% to 40% by weight. The separated organic phase (obtained at the end of the extraction) may then be concentrated to reach a concentration of lithium bis (fluorosulfonyl) imide salt of 30-60 wt. -%, preferably 40-50 wt. -%, wherein the concentration may be achieved by any evaporation means known to the skilled person.

The filter cake G mentioned above can be washed with an organic solvent S' selected from the following classes: esters, nitriles, ethers, chlorinated and aromatic solvents, and mixtures thereof. Preferably, the organic solvent S' is selected from dichloromethane, ethyl acetate, butyl acetate, tetrahydrofuran, acetonitrile, diethyl ether and valeronitrile, and mixtures thereof. In particular, the organic solvent S' is butyl acetate. The amount by weight of organic solvent S' used may range from 1 to 10 times the weight of the filter cake. The total amount of organic solvent S' intended for washing may be used in a single portion or in multiple portions for the purpose of, inter alia, optimizing the dissolution of lithium bis (fluorosulfonyl) imide salt. Preferably, the organic phase resulting from washing filter cake G has a weight content of lithium bis (fluorosulfonyl) imide salt ranging from 5% to 20% by weight. The organic phase resulting from the separated washed filter cake G may then be concentrated to a concentration of 30-60 wt.%, preferably 40-50 wt.% of lithium bis (fluorosulfonyl) imide salt, wherein said concentration may be achieved by any means of evaporation known to those skilled in the art. According to one embodiment, the organic phases resulting from the extraction of filtrate F and from the washing of filter cake G may be combined before the concentration step.

Example 1

To a stirred 1 liter reactor was introduced 394g of liquid bis (chlorosulfonyl) imide (HCSI) and 19.7g of liquid 1, 4-dioxane. The weight ratio between 1, 4-dioxane and HCSI was 5%. The mixture was stirred using a turbine with 6 inclined blades and brought to 40 ℃, after which hydrofluoric acid was introduced. The reaction is carried out by adjusting the temperature of the reaction medium at 40 ℃ and by continuous injection of gaseous HF. Gaseous HF is slowly injected directly into the liquid reaction medium through a dip tube. The total amount of HF injected was 110g, which corresponds to a molar ratio of HF to HCSI of 3. The rate of introduction of gaseous HF was adjusted to 37 g/h. The reaction time was 3 hours. The reaction was accompanied by the formation of HCl, which was continuously removed from the reactor. The gas leaving the reactor is sent to a water trap. When all the HF has been introduced, a stream of nitrogen at a flow rate of 50l/h is introduced into the reactor so as to strip the HF and HCl which may be dissolved in the reaction medium. This stripping was carried out for 5h and the medium temperature was maintained at 40 ℃. The stripping gas leaving the reactor is also sent to a water collector. After stripping, the reactor contained 336.3g of crude bis (fluorosulfonyl) imide (HFSI). The composition of this crude HFSI was analyzed by NMR.

Conversion of HCSI was complete and reached 100%. The yield of HFSI was 90.8%.

Example 2

To a stirred 1 liter reactor, 397g of liquid bis (chlorosulfonyl) imide (HCSI) and 12g of liquid 1, 4-dioxane were introduced. The weight ratio between 1, 4-dioxane and HCSI was 3%. The mixture was stirred using a turbine with 6 inclined blades and brought to 45 ℃, after which hydrofluoric acid was introduced. The reaction was carried out by adjusting the temperature of the reaction medium at 45 ℃ and by continuous injection of gaseous HF. Gaseous HF is slowly injected directly into the liquid reaction medium through a dip tube. The total amount of HF introduced was 100g, which corresponds to a molar ratio of HF to HCSI of 2.7. The rate of introduction of gaseous HF was adjusted to 38 g/h. The reaction time was 2 hours and 40 minutes. The reaction was accompanied by the formation of HCl, which was continuously removed from the reactor. The gas leaving the reactor is sent to a water collector. When all the HF has been introduced, a stream of nitrogen at a flow rate of 50l/h is introduced into the reactor so as to strip the HF and HCl which may be dissolved in the reaction medium. This stripping was carried out for 5h and the medium temperature was maintained at 45 ℃. The stripping gas leaving the reactor is also sent to a water collector.

After stripping, the reactor contained 339.5g of crude bis (fluorosulfonyl) imide (HFSI). The composition of this crude HFSI was analyzed by NMR.

Conversion of HCSI was complete and reached 100%. The yield of HFSI was 93.9%.