Process and system for the rapid separation of dimethyl ethylene ketone from isobutyric anhydride

Abstract

This invention provides a method and system for the rapid separation of dimethyl ketene (DME) from isobutyric anhydride. The method includes: the pyrolysis gas from the cracking reaction of an anhydride-based raw material (such as isobutyric anhydride) is adsorbed by an adsorbent material and cooled and separated by acoustic treatment; the resulting gaseous product is then absorbed or condensed to obtain an ketene compound. This invention utilizes an adsorbent material superimposed with an acoustic field-enhanced coalescence-condensation system, which promotes droplet aggregation, efficiently separates droplets carried in the gas, rapidly reduces the temperature of the cracking reaction gas, quickly separates DME, avoids side reactions during the process, increases the yield of ketene compounds, improves product selectivity in downstream polymerization reactions, and thus reduces the production cost of DME.

Description

Technical Field

[0001] This invention relates to the field of separation method technology, and provides a method and system for rapidly separating dimethyl ketone from isobutyric anhydride. Background Technology

[0002] Enketones, due to their high degree of unsaturation, readily undergo addition and polymerization reactions, making them important intermediates in organic synthesis and suitable for synthesizing a variety of compounds. Dimethyl ketene (DMK), a typical enketone, can be used to prepare 2,2,4,4-tetramethyl-1,3-cyclobutanediol (CBDO), which is then used in the production of high-performance polyesters, demonstrating significant market potential and economic value.

[0003] Patents US3201474A, US07747567A, and US08011584A disclose methods for preparing dimethyl ketene (DMK) from isobutyric anhydride (IBAN), wherein the thermal pyrolysis reaction temperature is 350-600°C, the absolute reaction pressure is controlled at 6.7-33.3 kPa, and the pyrolysis time is 4-8 s. Patent CN100439311C discloses a method for preparing DMK by pyrolysis of isobutyric anhydride. An inert gas and an IBAN-containing mixture are preheated at 300-340°C under normal pressure, and then pyrolyzed at 400-550°C for 0.05-10 s. Subsequently, the DMK gas mixture is separated from the condensed IBA and / or IBAN; the DMK-containing gas mixture is then contacted with a washing liquid to remove trace amounts of IBA and / or IBAN, thereby obtaining high-purity DMK.

[0004] The above patents only mention rapid cooling and separation of reaction products, but do not specify the exact quenching method for the pyrolysis gas. Patent CN114105748B mentions simultaneously feeding pre-cooled inert gas and high-temperature pyrolysis gas into a cyclone separator for rapid gas-liquid separation. Patent CN112079700B directly feeds the high-temperature pyrolysis products of isobutyric anhydride into a gas-liquid cyclone separator with heat exchange components, allowing the products to be condensed and separated simultaneously. It also controls the residence time of the gaseous products, reducing product loss during condensation and separation, and improving the yield of the target product.

[0005] In summary, the current industrial method for preparing dimethyl ketene mainly employs the isobutyric anhydride pyrolysis method. This method involves high reaction temperatures, numerous byproducts during pyrolysis, low product yield, severe reverse reactions during cooling, and low single-pass conversion. Research on methods suitable for the rapid cooling of isobutyric anhydride pyrolysis products is still limited; therefore, a new method is needed to address these issues. Summary of the Invention

[0006] To address the problems mentioned in the background section, this invention provides a method and system for the rapid separation of dimethyl ketene from isobutyric anhydride. This invention utilizes an adsorbent material superimposed with an acoustic field-enhanced coalescence-condensation system, which promotes droplet aggregation, efficiently accelerates the separation of droplets carried in the gas, rapidly reduces the temperature of the pyrolysis reaction gas, quickly separates ketene, avoids side reactions during the process, improves the yield of ketene compounds, enhances product selectivity in downstream polymerization reactions, and thus reduces the production cost of dimethyl ketene.

[0007] In a first aspect, a method for rapidly separating dimethyl ketene from isobutyric anhydride is provided, comprising: after the cracking reaction of an anhydride raw material (such as isobutyric anhydride), the cracked gas is adsorbed by an adsorbent material, treated by acoustic wave, and then cooled and separated; the resulting gaseous product is then absorbed or condensed to obtain an ketene compound.

[0008] In some embodiments, the adsorbent material is selected from solid alkali, C 50 -C 60 SiO2 or polar substances.

[0009] In some embodiments, the solid alkali is calcium carbonate or calcium oxide. In some embodiments, the polar substance is polyethylene glycol.

[0010] In some embodiments, the sound waves are generated by a sound wave generator, the sound wave frequency and / or sound pressure level of which are adjustable.

[0011] In some embodiments, the frequency of the sound wave is 1000-5000 Hz and the sound intensity is 100-160 dB.

[0012] In some embodiments, the acid anhydride raw material is mixed with a carrier gas, preheated and vaporized, and then enters the pyrolysis reactor for pyrolysis reaction.

[0013] In some embodiments, the preheating temperature is 230-350℃, the pyrolysis temperature is 350-800℃, the anhydride partial pressure is 5-100 kPa, and the residence time is 0.01-10 s.

[0014] In some embodiments, the adsorbent material is introduced by a carrier gas, and the flow rate of the pyrolysis gas is relevant, allowing for arbitrary adjustment of the carrier gas or the mass of the adsorbent material it carries. In some embodiments, the flow rate of the carrier gas is 30~60 ml / min, and the mass of the adsorbent material carried by the carrier gas is 0.5~1 g / h.

[0015] In some embodiments, the carrier gas is an inert gas, more preferably nitrogen, helium, or argon.

[0016] In a second aspect, a system for rapidly separating dimethyl ketene from isobutyric anhydride is provided, comprising: a quenching unit; The quenching unit includes an acoustic field agglomeration cooling device and a cyclone separation device; The acoustic field agglomeration cooling device includes an adsorption mechanism and an acoustic wave generator.

[0017] In some embodiments, the acoustic field agglomeration cooling device includes shell; The air inlet pipe, air outlet pipe, and liquid outlet are installed on the outer casing; Heat exchange mechanism for cooling; At least one sound wave generator; And at least one adsorption mechanism.

[0018] In some embodiments, the sound wave generator is disposed at the front end, middle end, or rear end of the sound field agglomeration cooling device.

[0019] In some embodiments, the adsorption mechanism is disposed at the front end, middle end, or rear end of the acoustic field agglomeration cooling device.

[0020] In some embodiments, the quenching unit further includes a cooler; preferably, the cooler is at least one of a microchannel cooler, an acoustic field agglomeration cooling device, and a cyclone separator; wherein the cooler can be added or removed as needed to improve the efficiency of subsequent separation.

[0021] In some embodiments, the number of inlets of the adsorption mechanism is at least one, and its location is at the front, middle or rear end of the acoustic agglomeration cooling device.

[0022] In some embodiments, the sound frequency and / or sound pressure level of the sound generator are adjustable.

[0023] In some embodiments, an adsorption material is introduced into the adsorption mechanism, the adsorption material being selected from silica, C 60 Calcium carbonate, MgO.

[0024] Compared with the prior art, one of the above technical solutions has the following advantages or beneficial effects: The method described in this invention accelerates the aggregation of fine droplets by introducing adsorption materials and the synergistic effect of sound waves, and then achieves rapid and efficient separation of the product through a gas-liquid separator, ultimately significantly improving the yield and purity of dimethyl ketene.

[0025] This invention utilizes acoustic agglomeration to induce relative vibration between droplets and powder materials, increasing the collision probability and rate, thereby promoting adhesion and forming larger agglomerates. It also leverages the different adsorption forces of adsorbent materials for acids, anhydrides, and ketenes (adsorption force of acids > anhydrides > ketenes) to accelerate the separation of acids, anhydrides, and ketenes, shorten the mixing time between the ketene products and pyrolysis byproducts, suppress reverse reactions, and improve the conversion rate of the pyrolysis reaction. Under the same pyrolysis process conditions, dimethyl ketene exhibits higher separation efficiency, higher space-time yield, and lower production costs. Attached Figure Description

[0026] Figure 1 The process flow diagram for the preparation of the example is shown.

[0027] Figure 2 This is a schematic diagram of the acoustic field agglomeration cooling device in the embodiment. In the figure, A is the air inlet; B1 and B2 are the input ports of the adsorbent material; 1 and 1' are the adsorption mechanisms; 2 and 2' are the sound wave generators; C is the liquid outlet; D is the air outlet; and 3 is the heat exchange mechanism.

[0028] Terminology Explanation Certain embodiments of the invention will now be described in detail, examples of which are illustrated by the accompanying structural and chemical formulas. The invention is intended to cover all alternatives, modifications, and equivalents, all of which are included within the scope of the invention as defined in the claims. Those skilled in the art will recognize that many similar or equivalent methods and materials can be used to practice the invention. The invention is by no means limited to the methods and materials described herein. In the event that one or more of the incorporated documents, patents, and similar materials differ from or contradict this application (including, but not limited to, defined terminology, application of terminology, described techniques, etc.), this application shall prevail.

[0029] It should be further appreciated that certain features of the invention, for clarity, have been described in multiple independent embodiments, but may also be provided in combination in a single embodiment. Conversely, various features of the invention, for brevity, have been described in a single embodiment, but may also be provided individually or in any suitable sub-combination.

[0030] Unless otherwise stated, all technical terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. All patents and publications related to this invention are incorporated herein by reference in their entirety.

[0031] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0032] In the following content, all numbers disclosed herein, whether or not they use words such as "approximately" or "about," are approximate values. The value of each number may vary by 1%, 2%, 5%, 7%, 8%, 10%, 15%, or 20%. Whenever a number with a value of N is disclosed, any numbers with values ​​of N+ / -1%, N+ / -2%, N+ / -3%, N+ / -5%, N+ / -7%, N+ / -8%, N+ / -10%, N+ / -15%, or N+ / -20% will be explicitly disclosed, where "+ / -" indicates addition or subtraction. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. The specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention in any way. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concepts of this disclosure. Such structures and techniques have also been described in many publications.

[0034] All reagents used in this invention can be purchased commercially or prepared by the methods described in this invention.

[0035] In this invention, room temperature refers to 15~35℃, preferably 25℃. All pressures in this invention refer to absolute pressure. The pyrolysis reactor is made of quartz glass, with a pyrolysis tube length of 56 cm and an inner diameter of 8 mm. The refrigerant is a 50% ethylene glycol aqueous solution, with temperature and flow rate controlled by a cryogenic circulating pump. The absorbent in the absorbent liquid is butyl acetate, and the absorption temperature is 0℃. The separation efficiency of the product is measured by the molar ratio of isobutyric acid and isobutyric anhydride in the condensate. A higher isobutyric acid ratio indicates a smaller amount of isobutyric anhydride generated by the reverse reaction of DMK during the separation process, resulting in higher separation efficiency.

[0036] like Figure 1As shown, the carrier gas is mixed with anhydride raw materials (such as isobutyric anhydride) in a preheater and heated to 230-350°C. After preheating and vaporization, the mixture enters the pyrolysis reactor and is pyrolyzed at 350-800°C, more preferably 400-500°C, with a pyrolysis partial pressure of 5-100 kPa and a residence time of 0.01-10 s. After the pyrolysis reaction, the pyrolysis gas enters a quench unit and is separated. The separated liquid phase product is collected. The separated gaseous product is absorbed by an absorbent or condensed and then collected to obtain ketene compounds. The carrier gas is an inert gas, more preferably nitrogen, helium, or argon.

[0037] The quenching unit includes a sound field aggregation cooling device and a cyclone separator. Coolers can be added or removed at any stage of the quenching unit as needed. For example, it can be combined as follows: a first-stage cooler (sound field aggregation cooling device) and a second-stage cooler (cyclone separator), or as follows: a first-stage cooler (microchannel cooler), a second-stage cooler (sound field aggregation cooling device), a third-stage cooler (sound field aggregation cooling device), and a fourth-stage cooler (cyclone separator).

[0038] like Figure 2 As shown, the acoustic field agglomeration cooling device includes an adsorption mechanism and a sound wave generator. The device includes a housing; an inlet pipe, an outlet pipe, and a liquid outlet disposed on the housing; a heat exchange mechanism for cooling; at least one sound wave generator; and at least one inlet for adsorbent material. The sound wave generator can be located at the front, middle, or rear end of the acoustic field agglomeration cooling device; the adsorption mechanism is located at the front, middle, or rear end of the device; the number of inlets for adsorbent material is at least one, and its location is at the front, middle, or rear end of the device; the sound wave frequency and / or sound pressure level of the sound wave generator are adjustable. Adsorbent material is introduced into the cooler, and the changes in the ratio of dimethyl ketene, isobutyric acid, and isobutyric anhydride in the absorption liquid are monitored by gas chromatography. Then, the sound wave frequency and sound pressure level are changed, and the changes in the ratio of dimethyl ketene, isobutyric acid, and isobutyric anhydride in the absorption liquid are monitored by gas chromatography. As needed, sound waves with different parameters can be used to conduct sound wave influence experiments, such as sound wave frequencies of 1000-5000 Hz and sound intensities of 100-160 dB.

[0039] The adsorption mechanism includes an adsorbent material, which can be a solid alkali such as calcium carbonate or magnesium oxide. 50 -C 60SiO2 and polar substances such as polyethylene glycol are used. Compared to ketene compounds, acids and anhydrides in the gaseous products are more easily adsorbed by the adsorbent material, thus accelerating the separation of acids and anhydrides from ketene compounds. Furthermore, introducing an acoustic generator can induce relative vibrations between droplets and between droplets and the adsorbent material, increasing the collision probability and rate, leading to the formation of larger aggregates and achieving rapid separation of dimethyl ketene. Acoustic waves also promote droplet aggregation, causing them to coalesce into larger droplets. Under the influence of acoustic waves, acids and anhydrides in the cooled pyrolysis gas can more quickly coalesce from small droplets into larger droplets, thereby accelerating the separation of fatty acids and anhydrides from ketene compounds.

[0040] Introducing adsorbent materials such as silica and C into the acoustic agglomeration cooling process 60 For substances like calcium carbonate and MgO, acoustic agglomeration can induce relative vibrations between droplets and powder materials, increasing the collision probability and rate, thus leading to adhesion and the formation of larger agglomerates. Utilizing the different adsorption forces of adsorbent materials for acids, acid anhydrides, and ketenes (adsorption force of acids > acid anhydrides > ketenes), the separation of acids / anhydrides from ketenes can be accelerated, shortening the mixing time between the ketene products and pyrolysis byproducts, inhibiting reverse reactions, and improving the conversion rate of the pyrolysis reaction. Under the same pyrolysis process conditions, dimethyl ketene exhibits high separation efficiency, higher space-time yield, and lower production costs.

[0041] This invention utilizes an adsorbent material superimposed with a sound field to enhance coalescence and condensation (sound field coalescence cooling device), which can promote droplet coalescence, accelerate separation, and reduce cooling time, thereby meeting the requirements of rapid separation of DMK.

[0042] Example 1 like Figure 1 As shown, isobutyric anhydride, the reactant, is pumped into the preheater at a rate of 0.1 mL / min using a metering pump. Nitrogen gas is regulated to a flow rate of 160 mL / min by a mass flow meter. After mixing with isobutyric anhydride (99% purity), the mixture is heated and vaporized in the preheater, reaching a temperature of 230°C. This vaporized gas is then introduced into the pyrolysis reactor, where a high-temperature pyrolysis reaction is carried out under 450°C conditions. The pyrolysis gas products enter the first cooling unit (acoustic agglomeration cooling device) of the quench unit, where nitrogen carries the carbon... 60 As an adsorbent (nitrogen flow rate 30 ml / min, C 60 A flow rate of 0.5 g / h is introduced into the first cooling unit through the adsorbent inlet pipe. This is because isobutyric acid and isobutyric anhydride are at C... 60 The adsorption capacity of C is greater than that of DMK, therefore it preferentially adsorbs on C 60The sound generator then emits a sound wave at a frequency of 2000 Hz and a sound intensity of 120 dB. Furthermore, when the sound generator is activated, the condensed or adsorbed acid and anhydride aggregates agglomerate more rapidly under the influence of the sound waves. Upon entering the second cooling unit, such as a cyclone separator, they are more easily separated. The separated condensate enters a liquid storage tank, and subsequent sampling is performed using gas chromatography. Gas chromatography detection can be performed via a three-way valve, one path leading to the gas chromatogram for composition and gas content analysis, and the other path either being absorbed by the absorbent or using liquid nitrogen condensation to collect DMK. The gas chromatography analysis conditions are: column: RTX®-Wax capillary column (PEG): 50 m × 0.20 mm × 0.5 μm; heating conditions: 180 °C held for 1 min, then increased to 200 °C at 10 °C / min and held for 16 min. In this embodiment, the isobutyric anhydride conversion rate is 82.8%, and the DMK selectivity is 97.2%.

[0043] Example 2 The difference from Example 1 is that MgO was introduced using nitrogen gas as the adsorbent (nitrogen flow rate 30 ml / min, MgO introduced at a mass of 1 g / h). The rest of the process is the same as in Example 1. In this example, the isobutyric anhydride conversion rate was 75.3%, and the DMK selectivity was 95.4%.

[0044] Example 3 The difference from Example 1 is that SiO2 introduced by nitrogen gas was used as the adsorbent (nitrogen flow rate 30 ml / min, SiO2 introduced mass 1 g / h). The rest of the process is the same as in Example 1. In this example, the isobutyric anhydride conversion rate was 79.1%, and the DMK selectivity was 95.2%.

[0045] Example 4 The difference from Example 1 is that C is introduced by nitrogen gas. 60 As an adsorbent (nitrogen flow rate 30 ml / min, C 60 The feed rate was 1 g / h. The remaining process was the same as in Example 1. In this example, the isobutyric anhydride conversion was 84.6%, and the DMK selectivity was 97.5%.

[0046] Examples 5-8 The difference from Example 1 is that the frequency and intensity of the sound waves emitted by the sound wave generator are different. The rest of the process is the same as in Example 1. Specifically: Table 1. Variations in sound wave frequency and intensity

[0047] Example 9 The difference from Example 1 is the addition of an adsorption mechanism and a sound wave generator in the first cooling unit. The rest of the process is the same as in Example 1. In this example, the isobutyric anhydride conversion rate is 86.7%, and the DMK selectivity is 98.7%.

[0048] Comparative Example 1 The difference from Example 1 is that only nitrogen gas (nitrogen flow rate 30 ml / min) is introduced into the adsorption mechanism of the first cooling unit, and no acoustic wave generator is used to send signal processing before the gas enters the second cooling unit (cyclone separator). The rest of the process is the same as in Example 1. In this example, the isobutyric anhydride conversion rate is 50.4%, and the DMK selectivity is 83.0%.

[0049] Comparative Example 2 The difference from Example 1 is that nitrogen gas is used to introduce C into the adsorption mechanism of the first cooling unit. 60 As an adsorbent (nitrogen flow rate 30 ml / min, C 60 The feed rate was 0.5 g / h, but no acoustic generator was used to send a signal for processing. The feed then entered the second cooling unit (cyclone separator). The remaining process was the same as in Example 1. In this example, the isobutyric anhydride conversion was 63.8%, and the DMK selectivity was 92.4%.

[0050] Comparative Example 3 The difference from Example 1 is that only nitrogen gas (nitrogen flow rate 30 ml / min) is introduced into the adsorption mechanism of the first cooling unit, and a sound wave generator emits a sound wave frequency of 2000 Hz and a sound intensity of 120 dB, which then enters the second cooling unit (cyclone separator). The rest of the process is the same as in Example 1. In this example, the isobutyric anhydride conversion rate is 64.2%, and the DMK selectivity is 91.6%.

[0051] The method of this invention has been described through preferred embodiments. Those skilled in the art will readily be able to modify or appropriately alter and combine the methods and applications described herein within the scope, spirit, and context of this invention to implement and apply the technology of this invention. Those skilled in the art can refer to the content herein to appropriately improve process parameters. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included within the scope of this invention.

Claims

1. A method for rapidly separating the product from isobutyric anhydride preparation of dimethyl ketene, characterized in that, include: After the cracking reaction of acid anhydride raw materials, the cracked gas is adsorbed by adsorption materials, treated by sound waves, and then cooled and separated. The resulting gaseous products are then absorbed or condensed to obtain ketene compounds.

2. The method according to claim 1, characterized in that, The adsorbent material is selected from solid alkali, C 50 -C 60 SiO2 or polar substances; the anhydride raw material is isobutyric anhydride; Preferably, the solid alkali is calcium carbonate or calcium oxide; preferably, the polar substance is polyethylene glycol.

3. The method according to claim 1, characterized in that, The sound waves are generated by a sound wave generator, and the sound wave frequency and / or sound pressure level of the sound wave generator are adjustable.

4. The method according to claim 1, characterized in that, The frequency of the sound wave is 1000-5000 Hz, and the sound intensity is 100-160 dB; Preferably, the acid anhydride raw material is mixed with the carrier gas, preheated and vaporized, and then enters the pyrolysis reactor for pyrolysis reaction; Preferably, the preheating temperature is 230-350℃, the pyrolysis temperature is 350-800℃, the anhydride partial pressure is 5-100 kPa, and the residence time is 0.01-10 s.

5. The method according to claim 1, characterized in that, The adsorbent material is introduced by a carrier gas with a flow rate of 30-60 ml / min and a mass of adsorbent material carried by the carrier gas of 0.5-1 g / h. Preferably, the carrier gas is an inert gas, and more preferably nitrogen, helium, or argon.

6. A system for rapidly separating the product of isobutyric anhydride preparation of dimethyl ketene, characterized in that, include: Cooling unit; The quenching unit includes an acoustic field agglomeration cooling device and a cyclone separation device; The acoustic field agglomeration cooling device includes a heat exchange mechanism, an adsorption mechanism, and an acoustic wave generator.

7. The system according to claim 6, characterized in that, The acoustic field agglomeration cooling device includes shell; The air inlet pipe, air outlet pipe, and liquid outlet are installed on the outer casing; Heat exchange mechanism for cooling; At least one sound wave generator; And at least one adsorption mechanism.

8. The system according to claim 6, characterized in that, The sound wave generator is located at the front end, middle end or rear end of the sound field agglomeration cooling device; Preferably, the cooling unit further includes a cooler; preferably, the cooler is at least one of a microchannel cooler, a sound field agglomeration cooling device, and a cyclone separator; preferably, the adsorption mechanism is disposed at the front end, middle end, or rear end of the sound field agglomeration cooling device.

9. The system according to claim 6, characterized in that, The adsorption mechanism has at least one inlet, located at the front, middle, or rear end of the acoustic agglomeration cooling device. Preferably, the sound wave frequency and / or sound pressure level of the sound wave generator are adjustable.

10. The system according to claim 6, characterized in that, The adsorption mechanism incorporates an adsorption material, which is selected from solid alkalis and C. 50 -C 60 SiO2 or polar substances; the anhydride raw material is isobutyric anhydride; Preferably, the solid alkali is calcium carbonate or calcium oxide; preferably, the polar substance is polyethylene glycol.

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