Method for preparing neopentyl glycol

Abstract

The present invention provides a process for preparing neopentyl glycol, the process comprising: feeding a feed stream comprising formaldehyde and isobutyraldehyde into an aldol reactor and subjecting the feed stream to an aldol condensation reaction in the presence of a catalyst to obtain a first reaction product comprising hydroxypivalaldehyde; feeding the first reaction product to an aldol purification column; feeding the upper discharge stream of the aldol purification column to a decanter and separating an organic phase stream comprising unreacted isobutyraldehyde and the catalyst and an aqueous phase stream comprising the catalyst salt; feeding the aqueous phase stream to a saponification reactor to reduce the catalyst salt to a catalyst and recover the catalyst; and feeding the lower discharge stream of the aldol purification column to a hydrogenation reactor and subjecting the lower discharge stream of the aldol purification column to a hydrogenation reaction to obtain neopentyl glycol.

Description

Technical Field

[0001] Cross - reference to related applications

[0002] This application claims the benefit of priority of Korean Patent Application No. 10-2023-0125459, filed on September 20, 2023, the entire content of which is incorporated herein by reference. Technical Field

[0004] The present invention relates to a method for preparing neopentyl glycol, and more particularly, to a method for preparing high-purity neopentyl glycol without using an extractant. Background Art

[0005] Neopentyl glycol can generally be prepared by subjecting isobutyraldehyde and formaldehyde to an aldol condensation reaction in the presence of a catalyst to form hydroxypivalaldehyde, and then subjecting the hydroxypivalaldehyde to a hydrogenation reaction.

[0006] In this case, in order to carry out the hydrogenation reaction of hydroxypivalaldehyde, a process of separating hydroxypivalaldehyde from the reaction product obtained after the aldol condensation reaction is essential. In the related art, in order to separate hydroxypivalaldehyde from the reaction product, an extraction process of extracting hydroxypivalaldehyde using an extractant such as 2-ethylhexanol is carried out. However, in the case of using an extractant, there are problems that the process design is complex, and the facility cost and energy consumption increase because a separate distillation apparatus needs to be used and the extractant needs to be recovered. In addition, due to the use of an extractant, it may be difficult to obtain high-purity neopentyl glycol because the extractant may remain in the final product neopentyl glycol. Therefore, a method capable of obtaining high-purity neopentyl glycol without using an extractant is needed.

[0007] Meanwhile, formic acid is generated by the Cannizzaro side reaction occurring in the aldol condensation reaction, and the catalyst is converted into a catalyst salt by the formic acid. In the related art, the catalyst salt is treated as wastewater in the form of an aqueous phase. In addition, in the process of purifying neopentyl glycol, hydroxypivalic acid-neopentyl glycol ester (HPNE) generated by the Tishchenko reaction, which is another side reaction of the aldol condensation reaction process, is completely discarded together with high-boiling by-products. However, hydroxypivalic acid-neopentyl glycol ester (HPNE) is a high-value-added product itself and needs to be recovered and utilized.

[0008] That is, there are environmental pollution problems caused by the discarded catalyst salt and HPNE, and there is a problem of increased production cost because the same amount of new catalyst as that discarded due to the generation of the catalyst salt must be continuously added.

[0009] Therefore, there is a need to introduce an environmentally friendly process that can reduce energy costs by recycling discarded catalysts and HPNE. Summary of the Invention

[0010] Technical Problem

[0011] In order to solve the problems mentioned in the background art, the object of the present invention is to obtain high-purity neopentyl glycol without using an extractant, and to provide an environmentally friendly effect that can further reduce the energy cost of the overall process.

[0012] Technical Solution

[0013] In a general aspect, a method for preparing neopentyl glycol includes: feeding a feed stream containing formaldehyde and isobutyraldehyde into an aldol reactor, and performing an aldol condensation reaction on the feed stream in the presence of a catalyst to obtain a first reaction product containing hydroxyneopentyl aldehyde; feeding the first reaction product into an aldol purification column, and obtaining an upper discharge stream of the aldol purification column containing unreacted isobutyraldehyde, a catalyst, and a catalyst salt, and a lower discharge stream of the aldol purification column containing hydroxyneopentyl aldehyde; feeding the upper discharge stream of the aldol purification column into a decanter, and separating an organic phase stream containing unreacted isobutyraldehyde and the catalyst and an aqueous phase stream containing the catalyst salt; recovering unreacted isobutyraldehyde and the catalyst from the organic phase stream, and feeding the aqueous phase stream into a saponification reactor to reduce the catalyst salt to the catalyst and recover the catalyst; feeding the lower discharge stream of the aldol purification column into a hydrogenation reactor, and performing a hydrogenation reaction on the lower discharge stream of the aldol purification column to obtain a second reaction product containing neopentyl glycol; and obtaining neopentyl glycol from the second reaction product.

[0014] Advantageous Effects

[0015] According to the method for preparing neopentyl glycol of the present invention, when separating hydroxyneopentyl aldehyde from the first reaction product, different from the related art that performs an extraction process, hydroxyneopentyl aldehyde is separated from the first reaction product through an aldol purification column without performing an extraction process. In this way, since there is no need to separately provide a distillation device for using and recycling an extractant, the process design can be simplified. Therefore, from the perspective of economic feasibility such as process facility costs and equipment costs, this is preferable. In addition, since no extraction process is performed and thus no extractant is used, the final product cannot contain an extractant. Therefore, high-purity neopentyl glycol can be obtained.

[0016] Furthermore, by controlling the ratio of the mass flow rate of water contained in the lower discharge stream of the aldol purification column to the mass flow rate of water contained in the feed stream to control the water content in the lower discharge stream of the aldol purification column, the total energy used in the process can be reduced, and the conversion rate of hydrogenation reaction to neopentyl glycol can be further increased.

[0017] Meanwhile, through the saponification reaction, the catalyst salt generated after the aldol condensation reaction is reduced to a catalyst, and the catalyst is recovered, enabling the effective reuse of the catalyst for the aldol condensation reaction. In this way, neopentyl glycol with economic feasibility can be prepared, and environmental pollution can be reduced.

[0018] In addition, in the present invention, hydroxyneopentanoic acid-neopentyl glycol ester, which is produced as a by-product of the aldol condensation reaction to obtain neopentyl glycol, can be recovered and obtained as a useful high-value-added product, which is effective in obtaining two types of products through one process. In this way, the production cost of preparing neopentyl glycol can be reduced, thereby improving the economic feasibility of the entire process. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a process flow diagram showing a method for preparing neopentyl glycol according to an embodiment of the present invention.

[0020] Figure 2 and Figure 3 is a process flow diagram showing a method for preparing neopentyl glycol according to a comparative example of the present invention. DETAILED DESCRIPTION

[0021] The terms and words used in the description and claims of the present invention should not be construed restrictively as having a conventional or dictionary meaning, but should be understood as having a meaning and concept consistent with the technical concept of the present invention based on the principle that the inventor can appropriately define the terms in order to describe their own invention in the best way.

[0022] The term "stream" in the present invention can refer to the flow of a fluid in a process or the fluid itself flowing through a pipeline. Specifically, "stream" can refer to both the fluid itself flowing through the pipeline connecting each device to each other and the flow of the fluid. In addition, the fluid can refer to one or more of gases and liquids.

[0023] In the present invention, in devices such as an extraction column, a purification column, a distillation column, and a recovery column, unless otherwise specified, the "lower part" of the device refers to a point at a height of 90% to 100% from the uppermost part to the lower position of the device, specifically, it can refer to the lowermost part (the bottom of the column). Similarly, unless otherwise specified, the "upper part" of the device refers to a point at a height of 0% to 10% from the uppermost part to the lower position of the device, specifically, it can refer to the uppermost part (the top of the column).

[0024] In the present invention, in devices such as an extraction column, a purification column, a distillation column, and a recovery column, unless otherwise specified, the operating temperature of the device can refer to the temperature at the upper part of the device. Similarly, unless otherwise specified, the operating pressure of the device can refer to the pressure at the upper part of the device.

[0025] In the following, the present invention will be described in more detail with reference to Figure 1 to help understand the present invention.

[0026] A method for preparing neopentyl glycol according to an embodiment of the present invention may include: subjecting formaldehyde (FA) and isobutyraldehyde (iBAL) to an aldol condensation reaction in an aldol reactor 10 in the presence of a catalyst to obtain a first reaction product containing hydroxypivalaldehyde (HPA); feeding the first reaction product into an aldol purification column 200, and obtaining an upper discharge stream of the aldol purification column containing unreacted isobutyraldehyde, the catalyst and catalyst salts, and a lower discharge stream of the aldol purification column containing hydroxypivalaldehyde; feeding the upper discharge stream of the aldol purification column into a decanter 250, and separating an organic phase stream containing unreacted isobutyraldehyde and the catalyst and an aqueous phase stream containing catalyst salts; recovering unreacted isobutyraldehyde and the catalyst from the organic phase stream, and feeding the aqueous phase stream into a saponification reactor 20 to reduce the catalyst salts to the catalyst and recover the catalyst; feeding the lower discharge stream of the aldol purification column into a hydrogenation reactor 30, and subjecting the lower discharge stream of the aldol purification column to a hydrogenation reaction to obtain a second reaction product containing neopentyl glycol (NPG); and obtaining neopentyl glycol from the second reaction product.

[0027] First, a method for preparing neopentyl glycol according to the present invention may include: feeding a feed stream 1 containing formaldehyde and isobutyraldehyde (iBAL) into an aldol reactor 10, and subjecting the feed stream 1 to an aldol condensation reaction in the presence of a catalyst to obtain a first reaction product containing hydroxypivalaldehyde (HPA).

[0028] The aldol condensation reaction may be carried out by reacting formaldehyde and IBAL in an aldol reactor 10 in the presence of a catalyst. Specifically, a mixed solution containing formaldehyde and IBAL may be fed as the feed stream 1 into the aldol reactor 10, and the mixed solution may be subjected to an aldol condensation reaction in the aldol reactor 10 in the presence of a catalyst, thereby obtaining a first reaction product containing HPA.

[0029] Here, formaldehyde may be used in an aqueous solution state to ensure reactivity and fluidity, and may contain a large amount of water. Such an aqueous formaldehyde solution may contain 30 to 64% by weight of water, more specifically, 45 to 55% by weight of water, relative to the total weight of the aqueous formaldehyde solution. In addition, the aqueous formaldehyde solution may further contain methanol to prevent formaldehyde polymerization. In this case, the content of methanol may be 0.1 to 15% by weight, more specifically, 0.1 to 5% by weight, relative to the total weight of the aqueous formaldehyde solution.

[0030] Formalin can be used as an aqueous solution of formaldehyde, in which case a formaldehyde concentration of 35 to 60% by weight can be effective in reducing wastewater.

[0031] The catalyst can be an amine compound. Specifically, it can include tertiary amine compounds such as trialkylamine, trimethylamine, triethylamine, tripropylamine, triisopropylamine or tributylamine. Preferably, the catalyst can include triethylamine (TEA). In the present invention, TEA can be used as the catalyst because it has the highest efficiency in the aldol condensation reaction.

[0032] The aldol condensation reaction temperature in the aldol reactor 10 can be 70°C to 100°C. When the aldol condensation reaction temperature is lower than 70°C, due to the low temperature, the aldol condensation reaction may not proceed smoothly, and thus it will be difficult to obtain a first reaction product containing HPA with a high conversion rate. When the aldol condensation reaction temperature exceeds 100°C, the formation of by-products during the aldol condensation reaction will accelerate.

[0033] The residence time in the aldol reactor 10 can be 0.1 hour to 3 hours. When the residence time is shorter than 0.1 hour, the HPA yield will decrease as the aldol condensation reaction proceeds. When the residence time is longer than 3 hours, as the process proceeds for a long time, the energy efficiency will decrease and an excessive amount of by-products will be generated.

[0034] In the aldol reactor 10 of the present invention, the aldol condensation reaction can be carried out under the above conditions, and HPA can be prepared. In this case, formic acid can be produced by the Cannizzaro side reaction occurring in the aldol condensation reaction, and the formic acid can react with TEA as the catalyst to produce a TEA salt, that is, a catalyst salt. In addition, hydroxy pivalic acid-neopentyl glycol ester (HPNE) can be produced by the Tishchenko reaction, which is another side reaction of the aldol condensation reaction. In the related art, HPNE is usually treated and discarded as a by-product. However, according to an embodiment of the present invention, HPNE can be separated and used as a valuable raw material.

[0035] As a result, the stream 2 discharged from the aldol reactor 10 can contain HPA, catalyst salt and HPNE as the first reaction product. In addition, the first reaction product can further contain unreacted IBAL, water and catalyst that are not reacted in the aldol condensation reaction.

[0036] Subsequently, a method for preparing neopentyl glycol according to an embodiment of the present invention can include: feeding the first reaction product into the aldol purification column 200, and obtaining an upper discharge stream 21 of the aldol purification column containing unreacted isobutyraldehyde, catalyst and catalyst salt, and a lower discharge stream of the aldol purification column containing hydroxy pivalaldehyde.

[0037] Specifically, in the aldol purification column 200, the first reaction product can be distilled to obtain an upper discharge stream 210 of the aldol purification column containing unreacted isobutyraldehyde, a catalyst, and a catalyst salt, and a lower discharge stream 220 of the aldol purification column containing HPNE and HPA.

[0038] According to the present invention, the ratio of the mass flow rate of water contained in the lower discharge stream 220 of the aldol purification column to the mass flow rate of water contained in the feed stream 1 can be from 0.10 to 0.60, more specifically, from 0.15 to 0.50 or from 0.20 to 0.30.

[0039] Specifically, when the mass flow rate ratio is less than 0.10 wt%, as the water content in the lower discharge stream 220 of the aldol purification column decreases, the energy consumption in the neopentyl glycol purification column 300 described below will decrease, but the energy consumption for maximizing the purification efficiency in the aldol purification column 200 will increase excessively. When the mass flow rate ratio exceeds 0.60 wt%, as the water content in the lower discharge stream 220 of the aldol purification column increases, the energy consumption in the aldol purification column 200 will decrease, but the energy consumption in the neopentyl glycol purification column 300 described below will increase. Therefore, considering the total energy used in the process, it is preferred to set the mass flow rate ratio within an appropriate range. In other words, considering the total energy used in the process, it is preferred to control the mass flow rate ratio to be from 0.10 to 0.60.

[0040] According to an embodiment of the present invention, the water content in the lower discharge stream 220 of the aldol purification column can be from 3 to 20 wt%, specifically, from 5 to 10 wt%. The water content in the lower discharge stream 220 of the aldol purification column can be controlled by controlling the ratio of the mass flow rate of water contained in the lower discharge stream 220 of the aldol purification column to the mass flow rate of water contained in the feed stream 1 to be from 0.10 to 0.60.

[0041] Specifically, when the water content in the lower discharge stream 220 of the aldol purification column is less than 3, it may be necessary to maximize the water content in the upper discharge stream 210 of the aldol purification column to control the water content. Thereafter, the upper discharge stream 210 of the aldol purification column can be fed to a decanter 250, and as much water as possible contained in the upper discharge stream 210 of the aldol purification column can be separated into an aqueous phase stream 240. For this purpose, the energy used in the aldol purification column 200 and the decanter 250 increases excessively, which may not be preferred in terms of economic feasibility.

[0042] When the water content in the lower discharge stream 220 of the aldol purification column exceeds 20, the amount of catalyst salt present in a dissociated state in the water also increases as the water content in the lower discharge stream 220 of the aldol purification column increases. Therefore, when water containing a large amount of catalyst salt is subjected to a hydrogenation reaction together with HPA, side reactions may occur due to the catalyst salt, and the conversion rate to NPG through the hydrogenation reaction may decrease. Thus, as the production of by-products due to a large amount of water and side reactions in the hydrogenation reactor 30 increases, in subsequent processes, for example, when separating and distilling by-products in the NPG purification column 300, the energy consumption increases excessively.

[0043] In order to prepare NPG by reacting HPA with hydrogen, it is necessary to separate HPA from the first reaction product. For this purpose, an extraction process for extracting HPA from the first reaction product is performed in the related art. However, in the present invention, when separating HPA from the first reaction product, the extraction process is not performed, but HPA is separated by the aldol purification column 200. As described above, since the extraction process is not performed when separating HPA from the first reaction product, an extractant is not required, and the final product does not contain the extractant. Therefore, high-quality NPG can be obtained. There is no need to additionally provide a separate column, for example, an extractant separation column, to finally separate the extractant. Therefore, the process is simplified, which can reduce the overall facility cost and process operation cost.

[0044] For this purpose, the operating temperature of the aldol purification column 200 can be 40 °C or higher, 45 °C or higher, 50 °C or higher, or 55 °C or higher, and 85 °C or lower, 90 °C or lower, 95 °C or lower, or 100 °C or lower. In addition, the operating pressure of the aldol purification column 200 can be 300 Torr or higher, 350 Torr or higher, 400 Torr or higher, or 450 Torr or higher, and 600 Torr or lower, 650 Torr or lower, 700 Torr or lower, or 760 Torr or lower. The aldol purification column 200 operates within the above temperature and pressure ranges so that the distillation carried out within the aldol purification column can proceed smoothly, and the separation between TEA as a relatively low-boiling material and HPA as a relatively high-boiling material can be easily carried out.

[0045] The method for preparing neopentyl glycol according to an embodiment of the present invention may include: feeding the upper discharge stream 250 of the aldol purification column into a decanter 250, and separating an organic phase stream 230 containing unreacted isobutyraldehyde and a catalyst and an aqueous phase stream 240 containing a catalyst salt.

[0046] Specifically, the upper discharge stream 210 of the aldol purification column can be fed into a decanter 250 provided upstream of the aldol purification column 200, and the upper discharge stream 210 of the aldol purification column can be separated into an organic phase stream 230 containing unreacted IBAL and a catalyst and an aqueous phase stream 240 containing a catalyst salt. In this case, the water contained in the aqueous phase stream 240 can be derived from an aqueous formaldehyde solution, and the catalyst salt can exist in a dissociated state in the water.

[0047] When a multi-stage distillation column is used to separate the first reaction product into a stream containing HPA, a stream containing unreacted IBAL and a catalyst, and a stream containing water without an extraction process, the problem is that it is difficult to obtain a stream containing water as a suitable feed to the saponification reactor. Specifically, when a multi-stage distillation column is used to separate the first reaction product, the organic substances (e.g., unreacted IBAL and a catalyst) and water contained in the first reaction product are not separately separated but are fed together into the saponification reactor. In this case, in the saponification reactor, excessive by-products caused by the organic substances will be generated. Therefore, in order to feed a stream containing water, specifically, a stream containing water from which a catalyst salt dissociates, into the saponification reactor, as described in the present invention, it is preferable to provide a decanter in which an organic phase stream containing organic substances and an aqueous phase stream containing water from which a catalyst salt dissociates are separated, and the aqueous phase stream is fed into the saponification reactor.

[0048] More specifically, in the present invention, through the decanter 250, the upper discharge stream 210 of the aldol purification column can be separated into layers to be separated into respective streams suitable for feeding into the saponification reactor 20 and the raw material recovery column 500 described below, specifically, an aqueous phase stream and an organic phase stream. In particular, in order to reduce the catalyst salt contained in the upper discharge stream 210 of the aldol purification column to a catalyst, the catalyst salt needs to be fed into the saponification reactor 20. According to an embodiment of the present invention, the catalyst salt can be fed into the saponification reactor to be reduced to a catalyst, and the catalyst can be recovered and recycled in the aldol reactor 10.

[0049] Since the catalyst salt mainly exists in a dissociated state in water, it is appropriate to separate the upper discharge stream 210 of the aldol purification column into an aqueous phase and an organic phase through the decanter 250 without providing a distillation column other than the aldol purification column.

[0050] Even when a multi-stage distillation column can be used to separate the first reaction product into a stream containing HPA, a stream containing unreacted IBAL and a catalyst, and a stream containing water, compared with the present invention in which the first reaction product is separated using the aldol purification column 200 and the decanter 250, the energy consumption and the cost of process facilities may increase, and it is not preferable in terms of the space utilization of the process facilities.

[0051] A method for preparing neopentyl glycol according to an embodiment of the present invention may include: recovering unreacted isobutyraldehyde and a catalyst from the organic phase stream 230, and feeding the aqueous phase stream 240 into a saponification reactor to reduce the catalyst salt to a catalyst and recover the catalyst.

[0052] Specifically, the organic phase stream 230 may contain unreacted IBAL and a catalyst, and may be fed into a raw material recovery column 500 described below. The aqueous phase stream 240 may contain a catalyst salt, and may be fed into the saponification reactor 20.

[0053] In the saponification reactor 20, the catalyst salt contained in the aqueous phase stream 240 may be reduced to a catalyst. The catalyst salt may be formed by side reactions caused by the above aldol condensation reaction.

[0054] The saponification reaction may be carried out by reacting the catalyst salt with an inorganic strong base such as sodium hydroxide (NaOH) added separately, so as to effectively reuse the reduced catalyst. For example, when TEA is used as the catalyst for the aldol condensation reaction, the TEA salt may be reduced to TEA according to the following reaction scheme 1.

[0055] [Reaction Scheme 1]

[0056] TEA salt + NaOH → TEA + Na salt

[0057] The temperature of the saponification reaction in the saponification reactor 20 may be 50 °C or higher, 55 °C or higher, or 60 °C or higher, and 90 °C or lower, 95 °C or lower, or 100 °C or lower. When the saponification reaction temperature is lower than 50 °C, due to the low temperature, the saponification reaction may not proceed smoothly, and thus, the conversion rate to the catalyst may decrease. When the saponification reaction temperature exceeds 100 °C, excessive by-products may be generated during the saponification reaction.

[0058] When the catalyst salt is not reduced to a catalyst by the saponification reaction and is fed into a subsequent process in a large amount, for example, into the hydrogenation reactor 30 described below, the hydrogenation reaction carried out in the hydrogenation reactor 30 may be adversely affected in the state of the catalyst salt. Therefore, it is necessary to remove the catalyst salt by reducing it to a catalyst in advance, and it is necessary to recover the reduced catalyst. Specifically, under the conditions of the hydrogenation reaction in the hydrogenation reactor 30, the catalyst salt may interfere with the action of the hydrogenation reaction catalyst required for the hydrogenation reaction, and may cause various side reactions, which may ultimately reduce the conversion rate of the hydrogenation reaction.

[0059] Therefore, the catalyst salt is reduced to a catalyst in the saponification reactor 20, and the catalyst is recovered in the raw material recovery column 500 described below, so that the introduction of the catalyst salt into the hydrogenation reactor 30 can be prevented, thereby minimizing the above various side effects.

[0060] In addition, the catalyst salt is reduced to a catalyst in the saponification reactor 20, enabling the catalyst to be effectively reused, thereby ensuring the cost competitiveness of the process. Furthermore, environmental pollution problems that may occur when treating the catalyst salt without reducing it can be solved.

[0061] Then, the saponification reactor effluent stream 21 containing the reduced catalyst, such as TEA, can be fed into the raw material recovery column 500.

[0062] According to the present invention, the unreacted isobutyraldehyde and the catalyst can be recovered from the organic phase stream 230 through the raw material recovery column 500, and the aqueous phase stream 240 can be fed into the saponification reactor 20 to reduce the catalyst salt to a catalyst and recover the catalyst.

[0063] The present invention may further include: feeding the organic phase stream 230 and the saponification reactor effluent stream 21 containing the reduced catalyst into the raw material recovery column 500, and feeding the upper effluent stream 510 of the raw material recovery column containing the unreacted isobutyraldehyde and the catalyst into the aldol reactor 10.

[0064] According to an embodiment of the present invention, the organic phase stream 230, the saponification reactor effluent stream 21, and the stream 310 containing the catalyst separated from the neopentyl glycol purification column can be distilled in the raw material recovery column 500, and the upper effluent stream 510 of the raw material recovery column containing the unreacted IBAL and the catalyst can be fed into the aldol reactor 10.

[0065] Specifically, the feed (organic phase stream 230, saponification reactor effluent stream 21, and the stream 310 containing the catalyst separated from the neopentyl glycol purification column described below) fed into the raw material recovery column 500 is distilled to obtain a lower effluent stream 520 of the raw material recovery column containing impurities (i-BuOH, MeOH, and unidentified by-products) and water, and an upper effluent stream 510 of the raw material recovery column containing the unreacted IBAL and the catalyst. The upper effluent stream 510 of the raw material recovery column can be fed into the aldol reactor 10.

[0066] The unreacted IBAL and the catalyst contained in the upper effluent stream 510 of the raw material recovery column are separated from the impurities and water in the raw material recovery column 500, and thus can be suitably reused as raw materials for the aldol condensation reaction in the aldol reactor 10. In addition, since the catalyst and IBAL used in the aldol reactor 10 are reused, the amount of newly added raw materials can be reduced, and the production cost used in the process can be lowered.

[0067] To this end, the operating temperature of the raw material recovery column 500 may be 50°C to 80°C, 55°C to 75°C, or 60°C to 70°C. In addition, the operating pressure of the raw material recovery column 500 may be 400 Torr to 760 Torr, specifically, 430 Torr to 700 Torr or 470 Torr to 650 Torr. When the raw material recovery column 500 operates within the above temperature and pressure ranges, the unreacted IBAL and catalyst contained in the feed to the raw material recovery column 500 can be separated from water and by-products and then recovered. Thus, the economic feasibility in terms of raw material utilization can be improved.

[0068] The saponification reactor effluent stream 21 and the organic phase stream 230 can be fed into the raw material recovery column 500, and the distillation of unreacted IBAL and TEA can be carried out in one recovery column, rather than applying separate recovery columns for each stream as in the related art. This is because the content of TEA contained in the saponification reactor effluent stream 21 and the organic phase stream 230 is similar, such that TEA and IBAL with a boiling point lower than TEA can be simultaneously distilled through the raw material distillation column 500.

[0069] According to an embodiment of the present invention, the ratio of the content of the catalyst in the saponification reactor effluent stream 21 to the content of the catalyst in the organic phase stream 230 may be 0.60 to 1.20, specifically, 0.65 to 1.15 or 0.70 to 1.10. By feeding streams with similar catalyst compositions into the raw material recovery column 500, the distillation and separation that are carried out for each stream in separate recovery columns can be carried out in one recovery column.

[0070] The method for preparing neopentyl glycol according to an embodiment of the present invention may include: feeding the lower discharge stream 220 of the aldol purification column into the hydrogenation reactor 30 and carrying out a hydrogenation reaction on the lower discharge stream 220 of the aldol purification column to obtain a second reaction product containing neopentyl glycol.

[0071] Specifically, the above-mentioned lower discharge stream 220 of the aldol purification column can be fed into the hydrogenation reactor 30, and the hydrogenation reaction can be carried out in the hydrogenation reactor 30. The hydrogenation reaction can be carried out by reacting HPA with additionally added hydrogen in the presence of a hydrogenation reaction catalyst. Through such a hydrogenation reaction, a second reaction product containing NPG as a product can be obtained.

[0072] According to the present invention, the second reaction product may further contain a catalyst, a catalyst salt, neopentyl glycol, and HPNE. HPNE may be produced as a by-product of the aldol condensation reaction in the aldol reactor 10, and the catalyst and the catalyst salt may be a small amount of catalyst and catalyst salt that are not separated in the aldol purification column 200. In this case, the catalyst salt may exist in a dissociated state in water, and the water is not separated into the aqueous phase stream 240 in the aldol purification column 200.

[0073] As described above, when a large amount of catalyst salts formed by the aldol condensation reaction, for example, TEA salts, are introduced into the hydrogenation reactor 30, various side reactions may occur, thereby reducing the conversion rate of the hydrogenation reaction. Therefore, the catalyst salts are reduced to catalysts and recovered by the saponification reactor 20 of the present invention, and by controlling the ratio of the mass flow rate of water contained in the lower discharge stream 220 of the aldol purification column to the mass flow rate of water contained in the first reaction product, the water content in the lower discharge stream 220 of the aldol purification column is controlled to (a) to (b) wt%, so that the amount of catalyst salts introduced into the hydrogenation reactor 30 can be reduced, thereby increasing the conversion rate of the hydrogenation reaction. That is, as the introduction amount of TEA salts that cause hydrogenation reaction catalyst poisoning (i.e., catalyst poisoning) decreases, the hydrogenation reaction can be activated.

[0074] The hydrogenation reaction can be carried out at a hydrogen pressure of 100 to 1,500 psig (pounds per square inch gauge) and a reaction temperature of 100 °C to 200 °C. In addition, as the hydrogenation reaction catalyst, a copper catalyst or a nickel catalyst can be used. As an example, the copper catalyst can be a CuO / BaO / SiO catalyst, and the CuO / BaO / SiO catalyst can be a (CuO)x(BaO)y(SiO)z catalyst (x, y, and z are wt%, x:y:z = 10 to 50:0 to 10:40 to 90, 10 to 50:1 to 10:40 to 89, or 29 to 50:1 to 10:40 to 70). Based on the sum of x, y, and z (100 wt%), the sum of x and y is preferably 20 to 50 (wt%) or 30 to 50 (wt%), within which the performance of the hydrogenation reaction catalyst is excellent and the lifespan is long. The amount of the nickel catalyst can be 2 to 10 wt% relative to the weight of the HPA.

[0075] The method for preparing neopentyl glycol according to an embodiment of the present invention may include: obtaining neopentyl glycol from the second reaction product.

[0076] Specifically, obtaining neopentyl glycol from the second reaction product may include: feeding the second reaction product into the neopentyl glycol purification column 300 and distilling the second reaction product to separate a stream 330 containing neopentyl glycol, a stream 310 containing the catalyst, a stream 340 containing the catalyst salt, and a stream 320 containing hydroxyneopentanoic acid-neopentyl glycol ester; and obtaining neopentyl glycol from the separated stream 330 containing neopentyl glycol, feeding the separated stream 310 containing the catalyst into the raw material recovery column 500, and feeding the separated stream 340 containing the catalyst salt into the saponification reactor 20.

[0077] More specifically, the second reaction product can be fed as a hydrogenation reactor effluent stream 21 into the NPG purification column 300 and can be distilled. In this case, the NPG purification column 300 can be one or more than two purification columns.

[0078] First, when the NPG purification column 300 is one purification column, the catalyst and catalyst salts, HPNE, and NPG can be separated from the upper, lower, and side portions of one purification column, respectively. In this case, the NPG can be obtained from the side portion at a height of 40% to 80% from the uppermost to the lowermost positions of the NPG purification column. Additionally, the NPG purification column can be, for example, a dividing wall distillation column. When the NPG purification column 300 is more than two purification columns, it can be operated by one or more than one NPG purification column for separating the stream containing the catalyst to the upper portion and one or more than one NPG purification column for separating the stream containing the catalyst salts to the upper portion. The stream containing HPNE or NPG can be separated and discharged from the lower portions of more than two NPG purification columns. That is, the second reaction product can be separated into the catalyst, catalyst salts, HPNE, and NPG by one or more than two NPG purification columns.

[0079] The NPG can ultimately be obtained from the separated NPG-containing stream 330. As described above, since no extractant is used in the process, high-purity NPG can be obtained, and the generation of by-products that may newly occur due to the use of the extractant can be prevented. Additionally, when an extractant is used as in the related art, another distillation column should be additionally provided to separate the extractant from the NPG, separately recover the extractant, and then recycle the extractant to the column where the extraction process is performed. However, when no extractant is used as in the present invention, such a distillation column is not required. That is, since at least two columns that should be provided when using an extractant do not need to be additionally provided, the process design is simpler than the related art, whereby the facility space can be minimized, and the energy consumption involved in the process can be reduced.

[0080] The separated catalyst-containing stream 310 can be fed into the raw material recovery column 500, and the separated catalyst salt-containing stream 340 can be fed into the saponification reactor 20. In this case, the separated catalyst salts can exist in the form of ions in water.

[0081] Therefore, the catalyst and the catalyst salt separated from the NPG purification column 300 are fed to the raw material recovery column 500 and the saponification reactor 30, respectively, so that the catalyst and the catalyst salt present in the system can be recovered. In addition, the separated catalyst salt fed to the saponification reactor 30 can be reduced to a catalyst and reused. In the related art, the stream containing the catalyst salt is treated as wastewater. However, in the present invention, as described above, the stream containing the catalyst can be fed to the saponification reactor 20, and the reduced catalyst can be recovered. In this way, the recovery rate of the catalyst used in the aldol condensation reaction in the aldol reactor 10 can be further increased.

[0082] The operating temperature of the NPG purification column 300 can be 60 °C or higher, 80 °C or higher, 100 °C or higher, 120 °C or higher, or 140 °C or higher, and 180 °C or lower, 185 °C or lower, 190 °C or lower, 195 °C or lower, or 200 °C or lower. In addition, the operating pressure of the NPG purification column 300 can be 40 Torr or higher, 90 Torr or higher, 120 Torr or higher, or 140 Torr or higher, and 300 Torr or lower, 400 Torr or lower, 500 Torr or lower, or 600 Torr or lower. When the NPG purification column 300 is operated within the above temperature and pressure ranges, the catalyst salt, the catalyst, NPG, and HPNE can be easily separated. Therefore, the content of by-products present in the NPG-containing stream 330 obtained in the present invention can be reduced, and high-purity NPG can thus be obtained.

[0083] Since HPNE generated by the side reaction of the aldol condensation reaction is partially reduced to NPG in the hydrogenation reactor 30 and the remaining part remains as HPNE, HPNE is introduced into the NPG purification column 300, which reduces the NPG yield. Therefore, HPNE is fed to the HPNE purification column 400 described below, so that additional NPG can be obtained, and HPNE, which is itself a high-value-added product, can be separately recovered and utilized. That is, HPNE can be commercialized separately from other heavy by-products, such as trimethylpentanediol (2,2,4-trimethyl-1,3-pentanediol (TMPD)), which is a by-product of the hydrogenation reaction.

[0084] The method for preparing neopentyl glycol according to an embodiment of the present invention may further include: feeding the stream 320 containing HPNE separated from the NPG purification column to the HPNE purification column 400, separating HPNE and NPG, and obtaining HPNE; and feeding the NPG to the NPG purification column.

[0085] Specifically, the stream 320 containing HPNE separated from the NPG purification column may further contain HPNE and trace amounts of NPG that were not separated in the NPG purification column 300. Thus, the stream 320 containing HPNE separated from the NPG purification column can be fed into the HPNE purification column 400, and distillation can be carried out to separate the overhead stream 410 of the HPNE purification column containing trace amounts of NPG, the side stream 430 of the HPNE purification column containing HPNE, and the bottom stream 420 of the HPNE purification column containing high-boiling by-products.

[0086] HPNE can be obtained from the side stream 430 of the HPNE purification column. Specifically, HPNE can be obtained from the side at a height of 50% to 80% from the top to the bottom position of the HPNE purification column. When HPNE is obtained at a height within the above range, the content of other materials such as NPG and high-boiling by-products in the side stream 430 of the HPNE purification column can be minimized, and HPNE can be obtained to the greatest extent.

[0087] As described above, the obtained HPNE can be recovered and utilized in various ways. For example, the obtained HPNE can be used as the main raw material for the synthesis and coating of polyesters as high-value-added products. Thus, since HPNE can be used as a raw material in other processes, the HPNE purification column 400 according to the present invention can improve the economic feasibility in terms of raw material utilization.

[0088] The overhead stream 410 of the HPNE purification column can be fed into the NPG purification column 400. Thus, the NPG that was not recovered in the NPG purification column 300 and was discharged can be recovered from the upper part of the HPNE purification column 400 (410), and thus, the recovery rate of NPG can be further improved by the HPNE purification column 400.

[0089] The operating temperature of the HPNE purification column 400 can be 100 °C or higher, 110 °C or higher, or 120 °C or higher, and 230 °C or lower, 240 °C or lower, or 250 °C or lower. In addition, the operating pressure of the HPNE purification column 400 can be 40 Torr or higher, 45 Torr or higher, or 50 Torr or higher, and 150 Torr or lower, 160 Torr or lower, or 170 Torr or lower. When the HPNE purification column 400 operates within the above temperature and pressure ranges, the separation of HPNE and NPG proceeds smoothly, such that the NPG obtained in the present invention can be additionally obtained, and HPNE can also be obtained as a high-value-added product.

[0090] Hereinafter, the present invention will be described in more detail with reference to the examples. However, the following examples are provided to illustrate the present invention. It will be apparent to those skilled in the art that various modifications and changes can be made without departing from the scope and concept of the present invention, and the scope of protection of the present invention is not limited thereto.

[0091] Example

[0092] Example 1

[0093] According to Figure 1 the process flow shown, the process for preparing neopentyl glycol (NPG) was simulated using the Aspen Plus simulator available from Aspen Technology, Inc.

[0094] Specifically, feed stream 1 containing formaldehyde (FA) and isobutyraldehyde (IBAL) was fed into the aldol reactor 10, and an aldol condensation reaction was carried out in the presence of a catalyst (TEA) to obtain a first reaction product containing hydroxypivalaldehyde (HPA). At this time, formaldehyde was an aqueous formaldehyde solution, and the aldol condensation reaction was carried out at a temperature of 85 °C.

[0095] The first reaction product was fed into the aldol purification column 200, and an upper discharge stream 210 of the aldol purification column containing unreacted IBAL, catalyst, and catalyst salt (TEA salt) and a lower discharge stream 220 of the aldol purification column containing HPA were obtained. At this time, the aldol purification column 200 was operated at an operating temperature of 87 °C and an operating pressure of 207 torr.

[0096] The ratio of the mass flow rate of water contained in the lower discharge stream 220 of the aldol purification column to the mass flow rate of water contained in the feed stream 1 was 0.278. The water content in the lower discharge stream 220 of the aldol purification column was 7.5 wt%.

[0097] The upper discharge stream 210 of the aldol purification column was fed into the decanter 250, and an organic phase stream 230 containing unreacted IBAL and catalyst and an aqueous phase stream 240 containing catalyst salt were separated. The organic phase stream 230 was fed into the raw material recovery column 500, and the aqueous phase stream 240 was fed into the saponification reactor 20.

[0098] In the saponification reactor 20, the catalyst salt contained in the aqueous phase stream 240 was reduced to a catalyst by reaction with sodium hydroxide (NaOH), and the saponification reactor discharge stream 21 containing the catalyst was fed into the raw material recovery column 500. At this time, the saponification reaction carried out in the saponification reactor 20 was carried out at a temperature of 83 °C.

[0099] The ratio of the content of the catalyst in the saponification reactor discharge stream 21 to the content of the catalyst in the above-mentioned organic phase stream 230 was 0.9.

[0100] In the feedstock recovery column 500, the distillation of the organic phase stream 230, the saponification reactor effluent stream 21, and the stream 310 containing the catalyst separated from the NPG purification column 300 described below is carried out to obtain an upper effluent stream 510 of the feedstock recovery column containing unreacted IBAL and the catalyst and a lower effluent stream 520 of the feedstock recovery column containing water and impurities. The upper effluent stream 510 of the feedstock recovery column is recycled to the aldol reactor 10. At this time, the feedstock recovery column 500 is operated at an operating temperature of 68.5 °C and an operating pressure of 510 Torr.

[0101] The lower effluent stream 220 of the aldol purification column is fed to the hydrogenation reactor 30 and a hydrogenation reaction is carried out to obtain a second reaction product containing NPG. At this time, the hydrogenation reaction is carried out at a temperature of 160 °C. The second reaction product contains a catalyst, a catalyst salt, NPG, and hydroxypivalic acid-neopentyl glycol ester (HPNE).

[0102] The second reaction product 31 is fed to the NPG purification column 300 and distilled to separate a stream 310 containing the catalyst, a stream 320 containing HPNE, a stream 330 containing NPG, and a stream 340 containing the catalyst salt. At this time, the NPG purification column is operated at an operating pressure of 154 Torr and an operating temperature of 168 °C.

[0103] NPG is obtained from the separated stream 330 containing NPG. The separated stream 310 containing the catalyst is fed to the feedstock recovery column 500, the separated stream 340 containing the catalyst salt is fed to the saponification reactor 20, and the separated stream 320 containing HPNE is fed to the HPNE purification column 400.

[0104] In the HPNE purification column 400, the separated stream 320 containing HPNE is distilled to separate a side effluent stream 430 of the HPNE purification column containing HPNE, an upper effluent stream 410 of the HPNE purification column containing trace amounts of NPG, and a lower effluent stream 420 of the HPNE purification column containing high-boiling by-products. HPNE is obtained from the side effluent stream 430 of the HPNE purification column, and the upper effluent stream 410 of the HPNE purification column is recycled to the NPG purification column 300. At this time, HPNE is obtained from the side at a height of 70% from the top to the bottom position of the HPNE purification column 400.

[0105] Comparative Example

[0106] Comparative Example 1

[0107] According to Figure 2 The process flow shown, the process for preparing neopentyl glycol (NPG) is simulated using the Aspen Plus simulator available from Aspen Technology, Inc.

[0108] Specifically, the feed stream 1 containing FA and IBAL is fed into the aldol reactor 10, and the aldol condensation reaction is carried out in the presence of a catalyst (TEA) to obtain a first reaction product containing HPA. At this time, the aldol condensation reaction is carried out at a temperature of 85 °C.

[0109] The first reaction product is fed into the aldol extraction column 100 and contacted with an extractant (2-ethylhexanol (2-EH)) to obtain an extract containing HPA and a raffinate containing a catalyst salt. At this time, the aldol extraction column 100 is operated at an operating temperature of 65 °C and an operating pressure of 760 Torr.

[0110] The raffinate is fed into the saponification reactor 20 as the raffinate stream 120, the catalyst salt is reacted with sodium hydroxide (NaOH) to be reduced to a catalyst, and the saponification reactor effluent stream 21 containing the reduced catalyst is fed into the catalyst recovery column 700. At this time, the saponification reaction carried out in the saponification reactor is carried out at a temperature of 83 °C.

[0111] The saponification reactor effluent stream 21 is distilled in the catalyst recovery column 700 to remove water and by-products (720), thereby obtaining a stream containing the catalyst from which water and by-products have been removed. The stream containing the catalyst from which water and by-products have been removed is fed into the raw material recovery column 500 as the upper discharge stream 710 of the catalyst recovery column.

[0112] The extraction stream 110 containing the above-mentioned extract is fed into the aldol purification column 200 and distilled to obtain the lower discharge stream 220 of the aldol purification column containing HPA and the upper discharge stream 210 of the aldol purification column containing unreacted IBAL and a catalyst. The ratio of the mass flow rate of water contained in the lower discharge stream 220 of the aldol purification column to the mass flow rate of water contained in the feed stream 1 is 0.278. At this time, the aldol purification column 200 is operated at an operating pressure of 207 Torr and an operating temperature of 87 °C. The upper discharge stream 210 of the aldol purification column is fed into the raw material recovery column 500, and the lower discharge stream 220 of the aldol purification column is fed into the hydrogenation reactor 30.

[0113] In the raw material recovery column 500, the upper discharge stream 210 of the aldol purification column, the upper discharge stream 710 of the catalyst recovery column, and the upper discharge stream 610 of the extractant recovery column described below are distilled to remove impurities (520), thereby obtaining a stream containing unreacted IBAL and a catalyst from which impurities have been removed. The stream containing unreacted isobutyraldehyde and a catalyst from which impurities have been removed is fed into the aldol reactor 10 as the upper discharge stream 510 of the raw material recovery column.

[0114] The lower discharge stream 220 of the aldol purification column is fed into the hydrogenation reactor 30 and subjected to a hydrogenation reaction to obtain a second reaction product containing NPG. At this time, the hydrogenation reaction is carried out at a temperature of 160 °C.

[0115] The second reaction product is fed into the neopentyl glycol purification column 300, and a stream 310 containing the catalyst and the extractant, a stream 330 containing NPG, and a stream 320 containing HPNE are separated. At this time, the neopentyl glycol purification column is operated at an operating pressure of 154 Torr and an operating temperature of 168 °C. NPG is obtained from the stream 330 containing NPG, the stream 310 containing the catalyst and the extractant is fed into the extractant recovery column 600, and the stream 320 containing HPNE is fed into the HPNE purification column 400 described below.

[0116] In the extractant recovery column 500, the stream 310 containing the catalyst and the extractant is distilled, the upper discharge stream 510 of the extractant recovery column containing the catalyst is fed into the aldol purification column 200, and the lower discharge stream 520 of the extractant recovery column containing the extractant is fed into the aldol extraction column 100.

[0117] In the HPNE purification column 400, the stream 320 containing HPNE is distilled to obtain an upper discharge stream 410 of the HPNE purification column containing NPG, a side discharge stream 430 of the HPNE purification column containing HPNE, and a lower discharge stream 420 of the HPNE purification column containing high-boiling by-products. The upper discharge stream 410 of the HPNE purification column is fed into the NPG purification column 300, and HPNE is obtained from the side discharge stream 430 of the HPNE purification column.

[0118] Comparative Example 2

[0119] According to Figure 3 the shown process flow, the neopentyl glycol (NPG) preparation process is simulated using the Aspen Plus simulator available from Aspen Technology, Inc.

[0120] In Comparative Example 2, the first reaction product 2 obtained by the same method as in Example 1 is fed into the aldol purification column 200, and an upper discharge stream 210 of the aldol purification column containing unreacted IBAL and the catalyst and a lower discharge stream 220 of the aldol purification column containing the catalyst salt (TEA salt) and HPA are obtained. The upper discharge stream 210 of the aldol purification column is fed into the raw material recovery column 500.

[0121] The lower discharge stream 220 of the aldol purification column is fed into the hydrogenation reactor 30 and subjected to a hydrogenation reaction to obtain a second reaction product containing NPG. The second reaction product contains the catalyst, the catalyst salt, NPG, and hydroxy pivalic acid neopentyl glycol ester (HPNE).

[0122] The second reaction product 31 is fed into the low-boiling by-product removal column 800, and a low-boiling by-product removal column overhead stream 810 containing the catalyst and a low-boiling by-product removal column bottom stream 820 containing the catalyst salt, NPG, and HPNE are obtained. The low-boiling by-product removal column overhead stream 810 is fed into the raw material recovery column 500, and the low-boiling by-product removal column bottom stream 820 is fed into the flash tank 40.

[0123] In the raw material recovery column 500, the aldol purification column overhead stream 210, the low-boiling by-product removal column overhead stream 810, and the stream 310 containing the catalyst separated from the NPG purification column 300 described below are distilled to obtain a raw material recovery column overhead stream 510 containing unreacted IBAL and the catalyst and a raw material recovery column bottom stream 520 containing water and impurities. The raw material recovery column overhead stream 510 is recycled to the aldol reactor 10.

[0124] In the flash tank 40, the low-boiling by-product removal column bottom stream 820 is distilled to separate a gas-phase stream 41 containing NPG and HPNE and an aqueous-phase stream 42 containing the catalyst salt. The gas-phase stream 41 is fed into the NPG purification column 300.

[0125] The aqueous-phase stream 42 is fed into the saponification reactor 20 to reduce the catalyst salt to the catalyst, and the saponification reactor effluent stream 21 containing the reduced catalyst is fed into the NPG purification column 300.

[0126] In the NPG purification column 300, the gas-phase stream 41 and the saponification reactor effluent stream 21 are distilled to separate a stream 310 containing the catalyst, a stream 320 containing HPNE, a stream 330 containing NPG, and a stream 340 containing the catalyst salt.

[0127] NPG is obtained from the separated stream 330 containing NPG. The separated stream 310 containing the catalyst is fed into the raw material recovery column 500, and the separated stream 320 containing HPNE is fed into the HPNE purification column 400.

[0128] In the HPNE purification column 400, the separated stream 320 containing HPNE is distilled to separate an HPNE purification column side stream 430 containing HPNE, an HPNE purification column overhead stream 410 containing trace amounts of NPG, and an HPNE purification column bottom stream 420 containing high-boiling by-products. HPNE is obtained from the HPNE purification column side stream 430, and the HPNE purification column overhead stream 410 is recycled to the NPG purification column 300.

[0129] Table 1 shows the mass flow ratio, FA flow ratio (FA / product), IBAL flow ratio (IBAL / product), and steam flow ratio (steam / product) in the examples and comparative examples.

[0130] The mass flow ratio represents the ratio of the mass flow rate of water contained in the discharge stream from the lower part of the aldol purification column to the mass flow rate of water contained in the feed stream.

[0131] The FA flow ratio (FA / product) is the ratio of the mass flow rate of FA contained in the feed stream to the mass flow rate of NPG contained in the stream containing NPG in the NPG purification column, and is expressed by converting the FA flow ratio of Comparative Example 1 to 100%.

[0132] The IBAL flow ratio (IBAL / product) is the ratio of the mass flow rate of IBAL contained in the feed stream to the mass flow rate of NPG contained in the stream containing NPG in the NPG purification column, and is expressed by converting the IBAL flow ratio of Comparative Example 1 to 100%.

[0133] The steam flow ratio (steam / product) is the ratio of the total mass flow rate of steam used in the process to the mass flow rate of NPG (tons per hour) contained in the stream containing NPG in the NPG purification column, and is expressed by converting the steam flow ratio of Comparative Example 1 to 100%.

[0134] [Table 1]

[0135]

[0136] Referring to Table 1, it can be confirmed that the FA flow ratio and IBAL flow ratio in Example 1 are lower than those in Comparative Example 2. This may mean that the aldol condensation reaction of FA and IBAL in Example 1 proceeds more smoothly than in Comparative Example 3. In addition, in Example 1, it can be confirmed that the steam flow ratio is the lowest, from which it can be confirmed that the total energy used in the process is reduced.

[0137] In Comparative Example 1 where an extractant is used in the extraction process, it can be confirmed that the final NPG product contains the extractant (2-EH), and the steam flow ratio increases compared to Example 1.

[0138] In Comparative Example 2 where a saponification reaction is carried out after the hydrogenation reaction, the FA flow ratio and IBAL flow ratio are the highest. Therefore, it can be confirmed that the amounts of FA and IBAL fed into the aldol reactor are the highest compared to the amount of the finally obtained NPG. That is, this may mean that the reactivity of FA and IBAL in the aldol reactor is the lowest. In addition, it can be confirmed that the steam flow ratio is also the highest among the examples and comparative examples.

[0139] [Explanation of Reference Numerals]

[0140] 10: Aldol Reactor 20: Saponification Reactor

[0141] 30: Hydrogenation Reactor

[0142] 200: Aldol Purification Tower 250: Decanter

[0143] 300: NPG Purification Tower 400: HPNE Purification Tower

[0144] 500: Raw Material Recovery Tower 600: Extractant Recovery Tower

[0145] 700: Catalyst Recovery Tower

[0146] 800: Low-Boiling Point By-Product Removal Tower 40: Flash Tank

Claims

1. A method for preparing neopentyl glycol, the method comprising: feeding a feed stream comprising formaldehyde and isobutyraldehyde into an aldol reactor and subjecting the feed stream to an aldol condensation reaction in the presence of a catalyst to obtain a first reaction product comprising hydroxypivaldehyde (HPA); feeding the first reaction product into an aldol purification column, and obtaining an aldol purification column upper effluent stream comprising unreacted isobutylaldehyde, catalyst and catalyst salt and an aldol purification column lower effluent stream comprising hydroxypivaldehyde; feeding the upper effluent stream of the aldol purification column into a decanter, and separating an organic phase stream containing unreacted isobutyraldehyde and the catalyst and an aqueous phase stream containing the catalyst salt; recovering unreacted isobutyraldehyde and catalyst from the organic phase stream and feeding the aqueous phase stream to a saponification reactor to reduce the catalyst salt to catalyst and recover the catalyst; feeding the lower effluent stream of the aldol purification tower into a hydrogenation reactor, and subjecting the lower effluent stream of the aldol purification tower to a hydrogenation reaction to obtain a second reaction product comprising neopentyl glycol; and Neopentyl glycol is obtained from the second reaction product.

2. The method according to claim 1, wherein: The catalyst includes one or more of trialkylamine, trimethylamine, tripropylamine, triisopropylamine, tributylamine and triethylamine (TEA).

3. The method according to claim 1, wherein: The ratio of the mass flow rate of water contained in the lower discharge stream of the aldol purification tower to the mass flow rate of water contained in the feed stream is 0.10 to 0.

60.

4. The method according to claim 1, wherein: The water content of the lower effluent stream of the aldol purification tower is 3 to 20% by weight.

5. The method according to claim 1, wherein: The operating temperature of the aldol purification tower is 40°C to 100°C. The operating pressure of the aldol purification column is 300 torr to 760 torr.

6. The method according to claim 1, wherein: recovering unreacted isobutyraldehyde and catalyst from the organic phase stream, and feeding the aqueous phase stream to a saponification reactor to reduce the catalyst salt to a catalyst and recover the catalyst through a feed recovery tower, The method further includes feeding the organic phase stream and the saponification reactor effluent stream containing the reduced catalyst into the raw material recovery tower, and feeding the raw material recovery tower upper effluent stream containing unreacted isobutyraldehyde and the catalyst into the aldol reactor.

7. The method according to claim 1, wherein: The ratio of the catalyst content in the saponification reactor discharge stream to the catalyst content in the organic phase stream is 0.60 to 1.

20.

8. The method according to claim 1, wherein: The second reaction product further comprises a catalyst, a catalyst salt, and hydroxypivalic acid-neopentyl glycol ester (HPNE).

9. The method according to claim 7 or 8, wherein: Obtaining neopentyl glycol from the second reaction product comprises: feeding the second reaction product to a neopentyl glycol purification column, and distilling the second reaction product to separate a stream comprising neopentyl glycol, a stream comprising the catalyst, a stream comprising the catalyst salt, and a stream comprising hydroxypivalic acid-neopentyl glycol ester; and Neopentyl glycol is obtained from the separated stream containing neopentyl glycol, the separated stream containing the catalyst is fed to the feed recovery column, and the separated stream containing the catalyst salt is fed to the saponification reactor.

10. The method according to claim 9, further comprising: Feeding the stream containing hydroxypivalic acid-neopentyl glycol ester separated in the neopentyl glycol purification tower to a hydroxypivalic acid-neopentyl glycol ester purification tower to separate hydroxypivalic acid-neopentyl glycol ester and neopentyl glycol, and obtaining hydroxypivalic acid-neopentyl glycol ester; and Neopentyl glycol is fed into the neopentyl glycol purification column.

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