A method for extracting dimethyl sulfone from distillation residue containing dimethyl sulfoxide and dimethyl sulfone

Abstract

The present invention relates to a method for extracting dimethyl sulfone from a distillation residue containing dimethyl sulfoxide and dimethyl sulfone, comprising the following steps: first crystallization: cooling the distillation residue to 30-80°C, separating a first crystal and a first recovered liquid; first recrystallization: adding the first crystal to propylene glycol methyl ether acetate and heating and dissolving to obtain a first mixture; cooling the first mixture to 30-80°C, separating a second crystal and a second recovered liquid. Different from the prior art, the present technical solution effectively extracts dimethyl sulfone from the first crystal by controlling the crystallization temperature and using propylene glycol methyl ether acetate solvent and adopting a recrystallization method, the recovery rate can reach 50-90%, and the purity of dimethyl sulfone can reach more than 99%, thereby improving the utilization rate of raw materials; energy saving and environmental protection, and effectively saving the cost of waste liquid and waste residue disposal.

Description

Technical Field

[0001] The present invention relates to the recovery and utilization of dimethyl sulfone, and in particular to a method for extracting dimethyl sulfone from distillation residue containing dimethyl sulfoxide and dimethyl sulfone. Background Art

[0002] With the popularity of smart handheld devices and mobile terminals, the electronic manufacturing industry and the optoelectronic industry have developed rapidly. In the manufacturing process of printed circuit boards, liquid crystal display panels, semiconductor integrated circuits, etc., it is necessary to form multiple layers of precise microcircuits on silicon wafers or glass substrates through multiple processes such as graphic mask irradiation exposure and etching, and then use a stripping liquid to remove the photoresist coated on the microcircuit protection area as a mask. This step is usually called photoresist removal. In the wet processing production process of printed circuit boards, the demolding (film stripping) process will also produce a large amount of stripping liquid in order to remove the residual solder on the surface of the waste circuit board.

[0003] DMSO is widely used in industry as a special cleaning liquid and a special stripping liquid used in the processing of electronic materials, etc. In addition, DMSO can also be used as a rinsing liquid in the rinsing process after the resist is stripped using a stripping liquid. In recent years, the production volume of liquid crystal devices and ICs has increased dramatically, and the use of stripping liquids or rinsing liquids that are indispensable in these manufacturing processes has increased significantly, and the amount of each used liquid generated has increased significantly, and the treatment of the used liquid has become an important issue.

[0004] DMSO is easily oxidized to produce MSM during the recovery process. MSM is an undesirable by-product in the distillation of organic waste containing dimethyl sulfoxide components. It is easy to crystallize at low temperatures and can be recovered in the distillation residue. Summary of the invention

[0005] In view of the above problems, the present application provides a method for extracting dimethyl sulfone from dimethyl sulfoxide and dimethyl sulfone distillation residue. The method can use simple equipment and methods to quickly extract high-purity dimethyl sulfone from distillation residue, avoids the waste of raw materials and environmental pollution, saves energy and protects the environment, and has economic and social value.

[0006] The present application first provides a method for extracting dimethyl sulfone from a distillation residue containing dimethyl sulfoxide and dimethyl sulfone, comprising the following steps:

[0007] First crystallization: cooling the distillation residue to 30-80°C, separating the first crystals and the first recovered liquid; first recrystallization: adding the first crystals to propylene glycol methyl ether acetate and heating to dissolve to obtain a first mixture; cooling the first mixture to 30-80°C, separating the second crystals and the second recovered liquid.

[0008] Different from the prior art, the present technical solution effectively extracts dimethyl sulfone from the first crystal by controlling the crystallization temperature and using propylene glycol methyl ether acetate solvent and adopting a recrystallization method, and the recovery rate can reach 50-90%, and the purity of dimethyl sulfone can reach more than 99%, thereby improving the utilization rate of raw materials; it is energy-saving and environmentally friendly, and effectively saves the cost of waste liquid and waste residue disposal.

[0009] In some embodiments, the method further comprises a secondary recrystallization step: secondary recrystallization: adding the second crystal to propylene glycol methyl ether acetate and heating to dissolve to obtain a second mixture; cooling the second mixture to 30-80° C., and separating the third crystal and the third recovered liquid. The secondary recrystallization can further purify the dimethyl sulfone obtained by the first recrystallization, and the obtained third crystal is dimethyl sulfone with a purity of more than 99.5%.

[0010] In some embodiments, in the recrystallization step, the mass ratio of propylene glycol methyl ether acetate to the dissolved crystals is 1-10:1. Propylene glycol methyl ether acetate is a high-grade solvent, and its molecules contain both ether bonds and carbonyl groups, and the carbonyl groups form an ester structure and contain alkyl groups. In the same molecule, there are both non-polar parts and polar parts. The functional groups of these two parts not only restrict and repel each other, but also play their inherent roles. Therefore, it has a certain solubility for both non-polar substances and polar substances. The applicant found in the study that the components (including impurities) in the crystals can be effectively dissolved in propylene glycol methyl ether acetate, but the larger the amount of solvent, the faster the dissolution rate.

[0011] In some embodiments, the recrystallization step is performed by stirring during dissolution and heating to 90°C at a heating rate of 3-10°C / h. Heating is beneficial to the dissolution of the crystals in the propylene glycol methyl ether acetate solvent, and the heating rate is controlled to avoid side reactions.

[0012] In some embodiments, the recovered liquid is distilled to recover propylene glycol methyl ether acetate. The propylene glycol methyl ether acetate in the recovered liquid can be recycled.

[0013] In some embodiments, the separation of the crystals from the recovered liquid is performed by a centrifuge, which can efficiently separate the solid and liquid and recover the crystals.

[0014] In some embodiments, the distillation residue contains 15-65% dimethyl sulfone, 5-25% dimethyl sulfoxide, and the rest is organic high boiling substances. Organic high boiling substances are difficult to remove by distillation due to their high boiling points, and most of them remain in the distillation residue in liquid form.

[0015] In some embodiments, the high boiling substances include one or more of N-methylpyrrolidone, diethylene glycol, diethylene glycol dibutyl ether, tributyl borate, diglycolamine, diethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol diethyl ether, diformate, ethyl benzoate, cyclopentane, γ-butyrolactone, tributyl borate, formamide, acetamide, and glycerol. The above are common high boiling substances in stripping liquid or rinsing liquid in the treatment of electronic materials, etc., and the technical solution includes but is not limited to the above high boiling substances.

[0016] In some embodiments, the recrystallization is carried out in a crystallization kettle, and the liquid level of the crystallization kettle does not exceed 90%. The optimal working liquid level of the crystallization kettle should be 20%-70%, so it is controlled at 20%-70% as much as possible, and the maximum does not exceed 90%.

[0017] In some embodiments, the second crystal is dimethyl sulfone with a purity exceeding 99.5%. 99.5% dimethyl sulfone reaches industrial grade usage standards and can be effectively utilized after drying.

[0018] In some embodiments, the number of recrystallizations is 3-6 times. Taking into account the different impurities, multiple recrystallizations can be performed. Taking into account energy consumption, efficiency, and yield, the number of recrystallizations should not exceed 6 times.

[0019] The above-mentioned records related to the invention content are only an overview of the technical solution of the present application. In order to enable ordinary technicians in the field to more clearly understand the technical solution of the present application, and then implement it according to the written contents of the specification, and to make the above-mentioned purpose and other purposes, features and advantages of the present application easier to understand, the specific implementation mode and drawings of the present application are explained below. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings are only used to illustrate the principles, implementation methods, applications, characteristics and effects of the specific embodiments of the present application and other related contents, and shall not be considered as limitations of the present application.

[0021] In the drawings of the specification:

[0022] Figure 1 Schematic diagram of the purification system in Example 1. DETAILED DESCRIPTION

[0023] In order to explain in detail the possible application scenarios, technical principles, specific schemes that can be implemented, and the purposes and effects that can be achieved, the following is a detailed description of the specific embodiments listed in conjunction with the accompanying drawings. The embodiments described herein are only used to more clearly illustrate the technical solutions of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0024] Reference to "embodiment" herein means that the specific features, structures or characteristics described in conjunction with the embodiment may be included in at least one embodiment of the present application. The term "embodiment" appearing in various places in the specification does not necessarily refer to the same embodiment, nor does it particularly limit its independence or association with other embodiments. In principle, in the present application, as long as there is no technical contradiction or conflict, the various technical features mentioned in the embodiments can be combined in any way to form a corresponding implementable technical solution.

[0025] Unless otherwise defined, the technical terms used in this document have the same meanings as those generally understood by those skilled in the art to which this application belongs; the use of relevant terms in this document is only for describing specific embodiments and is not intended to limit this application.

[0026] In the description of this application, the term "and / or" is an expression used to describe the logical relationship between objects, indicating that three relationships may exist, for example, A and / or B, which means: A exists, B exists, and A and B exist at the same time. In addition, the character " / " in this article generally indicates that the objects before and after are in an "or" logical relationship.

[0027] In the present application, terms such as “first” and “second” are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship of quantity, priority or sequence between these entities or operations.

[0028] Without further limitations, in this application, the words "include", "comprises", "has" or other similar expressions used in the sentences are intended to cover non-exclusive inclusion. These expressions do not exclude the presence of additional elements in the process, method or product including the elements, so that the process, method or product including a series of elements may include not only those limited elements, but also other elements not explicitly listed, or also include elements inherent to such process, method or product.

[0029] Similar to the understanding in the Examination Guidelines, in this application, expressions such as "greater than", "less than", "exceed" and the like are understood to exclude the number itself; expressions such as "above", "below", "within" and the like are understood to include the number itself. In addition, in the description of the embodiments of this application, "multiple" means more than two (including two), and similar expressions related to "multiple" are also understood in this way, such as "multiple groups", "multiple times", etc., unless otherwise clearly and specifically limited.

[0030] In the description of the embodiments of the present application, space-related expressions used, such as "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "vertical", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicate the orientation or position relationship based on the orientation or position relationship shown in the specific embodiments or drawings, and are only for the convenience of describing the specific embodiments of the present application or facilitating the reader's understanding, and do not indicate or imply that the referred device or component must have a specific position, a specific orientation, or be constructed or operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.

[0031] Unless otherwise expressly specified or limited, in the description of the embodiments of the present application, the terms such as "install", "connect", "connect", "fix", "set", etc. used should be understood in a broad sense. For example, the "connection" can be a fixed connection, a detachable connection, or an integrated setting; it can be a mechanical connection, an electrical connection, or a communication connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium; it can be the internal connection of two elements or the interaction relationship between two elements. For technicians in the technical field to which the present application belongs, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0032] The DMSO mentioned in this application is dimethyl sulfoxide, which is a colorless, odorless, transparent liquid at room temperature and a hygroscopic, flammable liquid. It has the characteristics of high polarity, high boiling point, good thermal stability, aprotic, miscible with water, and can be dissolved in most organic substances such as ethanol, propanol, benzene and chloroform.

[0033] The PMA described in this application is propylene glycol methyl ether acetate, with a molecular formula of C6H 12 O3, a colorless hygroscopic liquid with a special smell, is a high-grade solvent with multiple functional groups. Its molecules contain both ether bonds and carbonyl groups, which form an ester structure and contain alkyl groups. In the same molecule, there are both non-polar parts and polar parts. The functional groups of these two parts not only restrict and repel each other, but also play their own inherent roles. Therefore, PMA has a certain solubility for both non-polar and polar substances.

[0034] Example 1 used Figure 1The purification system shown includes centrifuge A\dissolving crystallization kettle A\centrifuge B\dissolving crystallization kettle B\centrifuge C; the dissolving crystallization kettle A and the dissolving crystallization kettle B are equipped with a stirring device and a circulating water temperature control device, and the kettle body can be heated by hot steam and cooled by cooling water as needed. During the dissolving process, the stirring speed can be adjusted according to the recrystallization situation. The stirring rate determines the crystal particle size. The faster the stirring, the smaller the crystal. The recrystallization particle size is controlled to be 0.2-20mm, which is convenient for discharging the crystallization kettle.

[0035] Example 1

[0036] Example 1 uses Figure 1 The purification system shown; the distillation residue contains 50% dimethyl sulfone, 15% dimethyl sulfoxide, and 35% high-boiling organic matter.

[0037] Separation crystallization: cooling the distillation residue to 30-80°C, and using centrifuge A to separate the first crystal and the residual liquid; first recrystallization: adding 5 parts by mass of propylene glycol methyl ether acetate to a dissolving crystallization kettle A, and then adding 1 part by mass of the first crystal, heating to above 90°C during stirring to completely dissolve the crystal, and the heating rate is 3-10°C / h, and the first crystal is dissolved in propylene glycol methyl ether acetate to obtain a first mixture; cooling the first mixture to 30-80°C for crystallization, and adding it to centrifuge B to separate the second crystal and the second recovered liquid; secondary recrystallization: adding 5 parts by mass of propylene glycol methyl ether acetate to a dissolving crystallization kettle B, and then adding 1 part by mass of the second crystal, and heating to above 90°C during stirring to completely dissolve the crystal, and the heating rate is 3-10°C / h, and the second crystal is dissolved in propylene glycol methyl ether acetate to obtain a second mixture; cooling the second mixture to 30-80°C for crystallization, and adding it to centrifuge C to separate the third crystal and the third recovered liquid. The recovered liquid is distilled to recover propylene glycol methyl ether acetate;

[0038] The third crystal is dried to obtain dimethyl sulfone with a purity exceeding 99.5% and a recovery rate of 80%.

[0039] Example 2

[0040] The distillation residue contains 65% dimethyl sulfone, 5% dimethyl sulfoxide, and 30% high-boiling organic matter. Separation crystallization: cool the distillation residue to 30-80°C, and use centrifuge A to separate the first crystal and the residue; first recrystallization: add 5 parts by mass of propylene glycol methyl ether acetate to the dissolution crystallization kettle, and then add 1 part by mass of the first crystal, and heat to above 90°C during stirring to completely dissolve the crystals. The heating rate is 3-10°C / h, and the first crystal is dissolved in propylene glycol methyl ether acetate to obtain a first mixture; cool the first mixture to 30-80°C for crystallization, and add it to the centrifuge to separate the second crystal and the second recovered liquid;

[0041] The recovered liquid is distilled to recover propylene glycol methyl ether acetate;

[0042] The second crystal was dried to obtain dimethyl sulfone with a purity exceeding 99% and a recovery rate of 60%.

[0043] Example 3

[0044] The distillation residue contains 15% dimethyl sulfone, 5% dimethyl sulfoxide, and 80% high-boiling organic matter. Separation crystallization: cool the distillation residue to 30-80°C, and use centrifuge A to separate the first crystal and the residue; first recrystallization: add 10 parts by mass of propylene glycol methyl ether acetate to the dissolution crystallization kettle, and then add 1 part by mass of the first crystal, and heat to above 90°C during stirring to completely dissolve the crystals. The heating rate is 3-10°C / h, and the first crystal is dissolved in propylene glycol methyl ether acetate to obtain a first mixture; cool the first mixture to 30-80°C for crystallization, and add it to the centrifuge to separate the second crystal and the second recovered liquid;

[0045] Secondary recrystallization: 10 parts by mass of propylene glycol methyl ether acetate are added to a dissolving and crystallizing kettle, and then 1 part by mass of the second crystal is added, and the temperature is raised to above 90°C during stirring to completely dissolve the crystals, and the heating rate is 3-10°C / h, and the second crystal is dissolved in propylene glycol methyl ether acetate to obtain a second mixture; the second mixture is cooled to 30-80°C for crystallization, and added to a centrifuge C to separate the third crystal and the third recovered liquid.

[0046] Three recrystallizations: 10 parts by weight of propylene glycol methyl ether acetate are added to a dissolving and crystallizing kettle, and then 1 part by weight of the third crystal is added, and the temperature is raised to above 90° C. during stirring to completely dissolve the crystals, and the heating rate is 3-10° C. / h, and the third crystal is dissolved in propylene glycol methyl ether acetate to obtain a third mixture; the third mixture is cooled to 30-80° C. for crystallization, and is added to a centrifuge to separate the fourth crystal and the fourth recovered liquid.

[0047] The fourth recrystallization is as follows: 5 parts by mass of propylene glycol methyl ether acetate are added into a dissolving and crystallizing kettle, and then 1 part by mass of the fourth crystal is added, and the temperature is raised to above 90° C. during stirring to completely dissolve the crystals, and the heating rate is 3-10° C. / h, and the fourth crystal is dissolved in propylene glycol methyl ether acetate to obtain a fourth mixture; the fourth mixture is cooled to 30-80° C. for crystallization, and is added into a centrifuge to separate the fifth crystal and the fifth recovered liquid.

[0048] The fifth recrystallization is as follows: 1 part by mass of propylene glycol methyl ether acetate is added to a dissolving and crystallizing kettle, and then 1 part by mass of the fifth crystal is added, and the temperature is raised to above 90° C. during stirring to completely dissolve the crystals, and the heating rate is 3-10° C. / h. The fifth crystal is dissolved in propylene glycol methyl ether acetate to obtain a fifth mixture; the fifth mixture is cooled to 30-80° C. for crystallization, and is added to a centrifuge to separate the sixth crystal and the sixth recovered liquid.

[0049] The recovered liquid is distilled to recover propylene glycol methyl ether acetate;

[0050] The sixth crystal is dried to obtain dimethyl sulfone with a purity exceeding 99.5%, and the recovery rate reaches 90%.

[0051] Example 4

[0052] The distillation residue contains 20% dimethyl sulfone, 25% dimethyl sulfoxide, and 55% high-boiling organic matter. Separation crystallization: cool the distillation residue to 30-80°C, and use centrifuge A to separate the first crystal and the residue; first recrystallization: add 10 parts by mass of propylene glycol methyl ether acetate to the dissolution crystallization kettle, and then add 1 part by mass of the first crystal, and heat to above 90°C during stirring to completely dissolve the crystals. The heating rate is 3-10°C / h, and the first crystal is dissolved in propylene glycol methyl ether acetate to obtain a first mixture; cool the first mixture to 30-80°C for crystallization, and add it to the centrifuge to separate the second crystal and the second recovered liquid;

[0053] Secondary recrystallization: 10 parts by mass of propylene glycol methyl ether acetate are added to a dissolving and crystallizing kettle, and then 1 part by mass of the second crystal is added, and the temperature is raised to above 90°C during stirring to completely dissolve the crystals, and the heating rate is 3-10°C / h, and the second crystal is dissolved in propylene glycol methyl ether acetate to obtain a second mixture; the second mixture is cooled to 30-80°C for crystallization, and added to a centrifuge C to separate the third crystal and the third recovered liquid.

[0054] Three recrystallizations: 10 parts by weight of propylene glycol methyl ether acetate are added to a dissolving and crystallizing kettle, and then 1 part by weight of the third crystal is added, and the temperature is raised to above 90° C. during stirring to completely dissolve the crystals, and the heating rate is 3-10° C. / h, and the third crystal is dissolved in propylene glycol methyl ether acetate to obtain a third mixture; the third mixture is cooled to 30-80° C. for crystallization, and is added to a centrifuge to separate the fourth crystal and the fourth recovered liquid.

[0055] The recovered liquid is distilled to recover propylene glycol methyl ether acetate;

[0056] The fourth crystal is dried to obtain dimethyl sulfone with a purity exceeding 99.5%, and the recovery rate reaches 75%.

[0057] Finally, it should be noted that although the above embodiments have been described in the specification and drawings of this application, this does not limit the scope of patent protection of this application. All technical solutions generated by replacing or modifying equivalent structures or equivalent processes based on the essential concept of this application using the contents recorded in the specification and drawings of this application, as well as directly or indirectly implementing the technical solutions of the above embodiments in other related technical fields, are included in the scope of patent protection of this application.

Claims

1. A method for extracting dimethyl sulfone from a distillation residue containing dimethyl sulfoxide and dimethyl sulfone, characterized in that: The following steps are involved: The first crystallization is to cool the distillation residue to 30-80° C., separate the first crystal and the first recovery liquid, wherein the distillation residue contains 15-65% of dimethyl sulfone, 5-25% of dimethyl sulfoxide, and the rest is organic high-boiling substances; the first recrystallization is to add the first crystal to propylene glycol methyl ether acetate and heat it to dissolve, so as to obtain a first mixture; the first mixture is cooled to 30-80° C., and the second crystal and the second recovery liquid are separated.

2. The method according to claim 1, characterized in that It also includes a secondary recrystallization step: Secondary recrystallization: adding the second crystals to propylene glycol methyl ether acetate and heating to dissolve to obtain a second mixture; cooling the second mixture to 30-80° C., and separating the third crystals and the third recovered liquid.

3. The method according to claim 1, characterized in that In the recrystallization step, the mass ratio of the propylene glycol methyl ether acetate solution to the dissolved crystals is 1-10:

1.

4. The method according to claim 1 or 2, characterized in that: In the recrystallization step, stirring is performed during dissolution and the temperature is raised to 90° C.; the heating rate is 3-10° C. / h.

5. The method according to claim 1 or 2, characterized in that: The recovered liquid is distilled to recover propylene glycol methyl ether acetate.

6. The method according to claim 1, characterized in that The crystals and the recovered liquid are separated by a centrifuge.

7. The method according to claim 1, characterized in that The high boiling substances include one or more of N-methylpyrrolidone, diethylene glycol, diethylene glycol dibutyl ether, diglycolamine, diethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol diethyl ether, ethyl benzoate, cyclopentane, γ-butyrolactone, tributyl borate, formamide, acetamide, and glycerol.

8. The method according to claim 1, characterized in that The recrystallization is carried out in a crystallization kettle, and the liquid level of the crystallization kettle does not exceed 90%.

9. The method according to any one of claims 1 to 8, characterized in that: The second crystals are dimethyl sulfone with a purity exceeding 99%.

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