Method for producing neopentyl glycol

Abstract

The present invention provides a method for producing neopentyl glycol, the method including the steps of: obtaining a first reaction product containing neopentyl glycol by performing a hydrogenation reaction in a first hydrogenation reactor; supplying the first reaction product to a flash drum to obtain hydrogen and a first degassed solution stream in which the hydrogen is degassed; supplying the hydrogen to a second hydrogenation reactor; supplying the first degassed solution stream to a first heat exchanger to reduce its temperature; supplying a portion of the reduced-temperature first degassed solution stream to the second hydrogenation reactor as a second branch stream; obtaining a second reaction product containing neopentyl glycol by performing a hydrogenation reaction in the second hydrogenation reactor; and introducing the second reaction product into a neopentyl glycol purification step to obtain neopentyl glycol.

Description

[Technical Field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0114486 filed on September 8, 2022, and Korean Patent Application No. 10-2023-0111976 filed on August 25, 2023, and all contents disclosed in the documents of the relevant Korean patent applications are incorporated herein by reference.

[0002] The present invention relates to a method for producing neopentyl glycol, and more particularly to a method for stably controlling heat removal in a hydrogenation reaction. [Background technology]

[0003] Neopentyl glycol can generally be produced by aldol condensation of isobutyraldehyde and formaldehyde in the presence of a catalyst to form hydroxypivaldehyde, which is then hydrogenated.

[0004] However, since the hydrogenation reaction is an exothermic reaction, the temperature inside the hydrogenation reactor where the hydrogenation reaction is carried out increases excessively, posing a safety hazard. In addition, the increase in temperature leads to the generation of a large amount of by-products due to side reactions, resulting in a decrease in the conversion rate to the target product, neopentyl glycol.

[0005] Therefore, a process must be introduced that can stably reduce the temperature increased by the hydrogenation reaction. Summary of the Invention [Problem to be solved by the invention]

[0006] The problem to be solved by the present invention is to provide a method for producing neopentyl glycol, which can obtain high-purity neopentyl glycol with a high recovery rate and can more stably reduce the temperature increased by the hydrogenation reaction, in order to solve the problems mentioned in the background of the invention. [Means for solving the problem]

[0007] According to one embodiment of the present invention for solving the above problems, the steps include: supplying a feed stream containing hydroxypivaldehyde and a hydrogen supply stream to a first hydrogenation reactor and hydrogenating them to obtain a first reaction product containing neopentyl glycol; supplying the first reaction product to a flash drum and obtaining an overhead discharge stream containing hydrogen and a first degassed solution stream from which the hydrogen has been removed; supplying the overhead discharge stream from the flash drum to a second hydrogenation reactor; supplying the first degassed solution stream to a first heat exchanger and cooling it; the second hydrogenation reactor; hydrogenating the hydrogen contained in the top discharge stream of the flash drum with the hydroxypivaldehyde contained in the second branch stream in the second hydrogenation reactor to obtain a second reaction product containing neopentyl glycol; and introducing the second reaction product into a neopentyl glycol purification step to obtain neopentyl glycol. [Effects of the Invention]

[0008] According to the method for producing neopentyl glycol of the present invention, by supplying the first reaction product from which gaseous hydrogen has been separated using a flash drum to the first heat exchanger, heat exchange efficiency can be increased compared to when a separate cooler is provided upstream of the flash drum. By first removing gaseous components containing gaseous hydrogen through the flash drum, the temperature in the first heat exchanger can be stably controlled when the degassed solution from which the gaseous components have been removed is supplied to the first heat exchanger. Specifically, when reducing the temperature increased by the exothermic reaction during the hydrogenation reaction, the degassed solution from which gaseous hydrogen has been separated first is introduced into the first heat exchanger, thereby improving the heat exchange efficiency in the first heat exchanger and enabling stable heat removal.

[0009] Furthermore, the waste heat from the first heat exchanger can be heat exchanged with low-temperature steam or with the bottom discharge stream of the aldol purification column in the aldol purification step, thereby enabling more efficient use of energy. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a process flowchart showing a hydrogenation reaction in a method for producing neopentyl glycol according to an embodiment of the present invention. [Figure 2] 1 is a process flowchart showing a hydrogenation reaction in a method for producing neopentyl glycol according to a comparative example of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] The terms and words used in the description of the present invention and the claims should not be interpreted in a limited way to their ordinary or dictionary meanings, but should be interpreted in a way that is consistent with the technical idea of ​​the present invention, based on the principle that the inventors can appropriately define the concepts of terms in order to best describe their invention.

[0012] In the present invention, the term "stream" can refer to the flow of fluid within a process, or the fluid itself flowing in a pipe. Specifically, the term "stream" can refer to both the fluid itself flowing in a pipe connecting each device and the flow of the fluid. Furthermore, the fluid can refer to one or more of gas and liquid, and does not exclude cases where the fluid contains solid components.

[0013] Meanwhile, in the present invention, in apparatuses such as extraction columns, purification columns, distillation columns, reactors, flash drums, and recovery columns, the "lower part" of the apparatus means, unless otherwise specified, a point 95% to 100% below the top of the apparatus, specifically the lowest end (tower bottom).Similarly, the "upper part" of the apparatus means, unless otherwise specified, a point 0% to 5% below the top of the apparatus, specifically the highest part (tower top).

[0014] Meanwhile, in the present invention, in apparatuses such as extraction columns, purification columns, distillation columns, and recovery columns, the operating temperature of the apparatus may refer to the temperature at the bottom of the apparatus unless otherwise specified. Similarly, the operating pressure of the apparatus may refer to the pressure at the top of the apparatus unless otherwise specified.

[0015] To facilitate understanding of the present invention, the present invention will now be described in more detail with reference to FIG.

[0016] According to one embodiment of the present invention, the method includes the steps of: supplying a feed stream containing hydroxypivaldehyde and a hydrogen supply stream to a first hydrogenation reactor and hydrogenating them to obtain a first reaction product containing neopentyl glycol; supplying the first reaction product to a flash drum to obtain an overhead discharge stream containing hydrogen and a first degassed solution stream from which the hydrogen has been removed; supplying the overhead discharge stream from the flash drum to a second hydrogenation reactor; supplying the first degassed solution stream to a first heat exchanger to reduce the temperature; and The method for producing neopentyl glycol includes the steps of circulating a portion of the stream as a first branch stream to a first hydrogenation reactor and supplying the remainder as a second branch stream to the second hydrogenation reactor, hydrogenating hydrogen contained in the top discharge stream of the flash drum with hydroxypivaldehyde contained in the second branch stream in the second hydrogenation reactor to obtain a second reaction product containing neopentyl glycol, and introducing the second reaction product into a neopentyl glycol purification step to obtain neopentyl glycol.

[0017] First, a method for producing neopentyl glycol according to one embodiment of the present invention may include a step of supplying a feed stream containing hydroxypivaldehyde and a hydrogen supply stream containing hydrogen to a first hydrogenation reactor and hydrogenating them to obtain a first reaction product containing neopentyl glycol.

[0018] According to one embodiment of the present invention, the feedstream containing hydroxypivaldehyde can be obtained from a feedstream production process including: an aldol reaction step in which a condensation reaction product is obtained by aldol condensation reaction of an aqueous formaldehyde solution with isobutyraldehyde in the presence of a catalyst; an aldol extraction step in which the condensation reaction product is contacted with an extractant to obtain an extract and a raffinate; a saponification reaction step in which the raffinate is reduced with a catalyst; and an aldol purification step in which the catalyst and the extract are distilled to separate a fraction containing hydroxypivaldehyde as a feedstream.

[0019] The feedstream production step may be a series of steps performed to produce a feedstream to be supplied to the first hydrogenation reactor, and may include an aldol reaction step, an aldol extraction step, a saponification reaction step, and an aldol purification step.

[0020] Specifically, the aldol condensation reaction temperature may be 70° C. to 100° C., and the aldol condensation reaction time may be 0.1 to 3 hours. Under these aldol condensation reaction conditions, an aldol condensation reaction of an aqueous formaldehyde (FA) solution and isobutylaldehyde (IBAL) may occur in the presence of a catalyst to produce a catalyst salt and hydroxypivaldehyde (HPA).

[0021] Here, the formaldehyde aqueous solution may be formalin, and using a formaldehyde concentration of 35 to 45 wt% can be effective in reducing wastewater. This formaldehyde aqueous solution may contain 40 to 64 wt%, more specifically 45 to 55 wt%, of water based on the total weight of the formaldehyde aqueous solution, and may contain methanol to prevent polymerization of formaldehyde. In this case, the content of the methanol based on the total weight of the formaldehyde aqueous solution may be 0.1 to 15 wt%, more specifically 0.1 to 5 wt%.

[0022] The catalyst may be an amine-based compound. Specifically, tertiary amine compounds such as trialkylamine, trimethylamine, triethylamine, tripropylamine, triisopropylamine, and tributylamine may be suitable. More specifically, the catalyst may include triethylamine (TEA). In the present invention, TEA has the highest efficiency in the aldol condensation reaction and can be used as the catalyst.

[0023] Meanwhile, the catalyst salt can be produced by reacting formic acid generated in a Cannizzaro side reaction that occurs in the aldol condensation reaction with the catalyst.

[0024] In addition, hydroxypivalic acid-neopentylglycol ester (HPNE) can be further produced by the Tishchenko reaction, which is another side reaction of the aldol condensation reaction. Therefore, a condensation reaction product containing the catalyst salt, HPNE, and HPA can be obtained in the aldol reaction process.

[0025] The condensation reaction product can then be contacted with an extractant to perform an aldol extraction process, yielding an organic extract containing the catalyst, unreacted IBAL, the extractant, and HPA, and a liquid raffinate containing the catalyst salt. Here, the unreacted IBAL can be IBAL that did not undergo aldol condensation in the aldol reaction process. The catalyst salt can exist in a dissociated state in water, and the water can be derived from an aqueous formic acid solution.

[0026] Here, the extractant may be an aliphatic alcohol, preferably 2-ethylhexanol (2-EH). Since HPA contained in the condensation reaction product is soluble in 2-EH, it can be preferably used in an aldol extraction process using a liquid-liquid contact extraction apparatus.

[0027] Meanwhile, the operating temperature of one or more aldol extraction columns used in the aldol extraction step may be 40° C. to 90° C. Since the aldol extraction columns are operated at a temperature within this range, phase separation into an organic phase and a liquid phase can be easily achieved.

[0028] Meanwhile, a saponification process can be carried out in which the raffinate containing the catalyst salt is saponified to reduce the catalyst salt to a catalyst. In the saponification process, the catalyst salt can be saponified by reacting with a separately added strong inorganic base such as sodium hydroxide (NaOH), thereby reducing the catalyst salt to a catalyst.

[0029] Meanwhile, the aldol purification step can be a step of distilling the reduced catalyst obtained from the saponification reaction step and the extract separated from the aldol extraction step to separate them into unreacted IBAL and catalyst, and HPA and extractant. The separated unreacted IBAL and catalyst can be recycled to the aldol reaction step and reused as raw materials for the aldol condensation reaction. Meanwhile, the HPA and extractant separated from the unreacted IBAL and catalyst can be supplied to the first hydrogenation reactor 100 as feedstream 1 of the present invention.

[0030] Specifically, the aldol purification process may be performed using one or more aldol purification columns. First, when the aldol purification process is performed using one aldol purification column, unreacted IBAL and the catalyst may be separated from the top of the single aldol purification column, and HPA and the extractant may be separated from the bottom. On the other hand, when the aldol purification process is performed using two or more aldol purification columns, the process may be performed via one or more aldol purification columns that separate unreacted IBAL from the top and one or more aldol purification columns that separate the catalyst from the top. A stream containing HPA or the extractant may be separated and discharged from the bottom of the two or more aldol purification columns, and this may be supplied to the first hydrogenation reactor 100 as feed stream 1 of the present invention, as described above.

[0031] The streams supplied to the first hydrogenation reactor 100 may be the feed stream 1 and the hydrogen supply stream 3. Here, the hydrogen supply stream 3 may contain compressed hydrogen, and the compressed hydrogen may be fresh hydrogen introduced via the hydrogen input stream 2 and compressed through a compressor 60. In the first hydrogenation reactor 100, a hydrogenation reaction of the HPA contained in the feed stream 1 and the compressed hydrogen contained in the hydrogen supply stream 3 may be carried out to produce neopentyl glycol (NPG). Here, the hydrogenation reaction may be carried out in the presence of a hydrogenation catalyst.

[0032] The hydrogenation catalyst may be a copper-based catalyst or a nickel catalyst. An example of the copper-based catalyst is a CuO / BaO / SiO catalyst. The CuO / BaO / SiO catalyst may be (CuO)x(BaO)y(SiO)z (x, y, and z are in weight percent, and x:y:z = 10-50:0-10:40-90, 10-50:1-10:40-89, or 29-50:1-10:40-70). The sum of x and y is preferably 20-50 (wt%) or 30-50 (wt%) based on the total sum of x, y, and z (100 wt%). Within this range, the hydrogenation catalyst exhibits excellent performance and a long life.

[0033] However, the hydrogenation reaction is fundamentally an exothermic reaction, which can make it difficult to control the temperature inside the hydrogenation reactor where the hydrogenation reaction is carried out. Therefore, as the hydrogenation reaction proceeds, the temperature inside the hydrogenation reactor may increase excessively, resulting in safety issues. Furthermore, side reactions caused by the temperature increase may produce by-products, such as trimethylpentanediol (2,2,4-trimethyl-1,3-pentanediol; TMPD), which may reduce the conversion rate to NPG, which is the target of the present invention. Therefore, heat removal is required to reduce the temperature increase caused by the hydrogenation reaction.

[0034] Meanwhile, the operating temperature of the first hydrogenation reactor 100 may be 100°C to 200°C, specifically 130°C to 180°C, or 150°C to 170°C, and the operating pressure may be 20 kg / cm 2 ~50kg / cm 2 , specifically 30 kg / cm 2 ~45kg / cm 2 , 35kg / cm 2 ~45kg / cm 2 By operating the first hydrogenation reactor 100 within the above range, the hydrogenation reaction between HPA and hydrogen can be carried out smoothly, and NPG can be obtained at a high conversion rate.

[0035] A first reaction product containing NPG can be obtained by the hydrogenation reaction performed in the first hydrogenation reactor 100. In addition, the first reaction product may also contain hydrogen that is unreacted during the hydrogenation reaction. Depending on the operating conditions of the process, if the hydrogen fraction in the first hydrogenation reactor 100 is high, the hydrogen fraction contained in the first reaction product may also increase. Thus, if the hydrogen fraction in the first reaction product is high, the hydrogen may exist not only as liquid hydrogen but also as gaseous hydrogen.

[0036] Then, the method for producing neopentyl glycol according to one embodiment of the present invention may include a step of supplying the first reaction product as a first hydrogenation reactor discharge stream 110 to a flash drum 300, and obtaining a top discharge stream 320 containing hydrogen and a first degassed solution stream 310 from which the hydrogen has been degassed.

[0037] Specifically, the first reaction product can be distilled in the flash drum 300 and separated into an upper flash drum fraction containing gaseous components and a lower flash drum fraction containing a first degassed solution. The gaseous components can specifically include gaseous hydrogen. The first degassed solution can be the residue remaining after the gaseous components have been removed from the first reaction product, and can specifically include liquid hydrogen, unreacted HPA, and NPG.

[0038] Here, the operating temperature of the flash drum 300 can be 100°C to 200°C, specifically 130°C to 180°C, or 150°C to 170°C. The operating pressure of the flash drum 300 can be 20 kg / cm. 2 ~60kg / cm 2 , specifically 25 kg / cm 2 ~55kg / cm 2 , 20kg / cm 2 ~40kg / cm 2 By operating the flash drum 300 at a temperature and pressure within the above ranges, it may be possible to easily separate gaseous hydrogen from the first reaction product flowing into the flash drum 300.

[0039] Meanwhile, a method for producing neopentyl glycol according to one embodiment of the present invention may include the steps of supplying the top discharge stream 320 of the flash drum to a second hydrogenation reactor 200, and supplying the first degassed solution stream 310 to a first heat exchanger 10 to reduce the temperature.

[0040] Specifically, the upper fraction of the vapor phase of the flash drum 300 can be supplied to the second hydrogenation reactor 200 as the upper discharge stream 320 of the flash drum, and the lower fraction of the liquid phase of the flash drum 300 can be supplied to the first heat exchanger 10 as the first degassed solution stream 310.

[0041] The liquid phase hydrogen content in the first degassed solution stream 310 may be 30 ppm or less, 25 ppm or less, or 20 ppm or less. By containing the hydrogen in the first degassed solution stream 310 within this range, it is possible to easily control the temperature of the first degassed solution stream 310 supplied to the first heat exchanger 10 (described below) within an appropriate range. Here, the hydrogen contained in the first degassed solution stream 310 may exist in a liquid phase.

[0042] According to one embodiment of the present invention, the first degassed solution stream 310 can be supplied to the first heat exchanger 10 to be cooled. Specifically, the first degassed solution stream 310, from which gaseous hydrogen has been removed via the flash drum 300, can be cooled in the first heat exchanger 10, thereby increasing the heat exchange efficiency of the first heat exchanger 10. For example, if a stream with a high hydrogen fraction is directly input to a heat exchanger without passing through a flash drum, the high content of relatively light components in the stream with a high hydrogen fraction may cause a decrease in the logarithmic mean temperature difference (LMTD) of the heat exchanger, which may result in a decrease in the performance of the heat exchanger and make heat removal difficult.

[0043] Therefore, the first heat exchanger 10 of the present invention reduces the temperature of the first degassed solution stream 310 from which gaseous hydrogen has been degassed by the flash drum 300, thereby enabling stable heat removal. As described above, heat removal is necessary to address the problems of process safety, unstable process flow, and reduced conversion to NPG due to exothermic reactions. Here, the heat removal can be performed using the heat exchanger of the present invention, and can involve reducing the temperature increased by the exothermic reaction to within an optimal temperature range.

[0044] Meanwhile, the first degassed solution stream 310 is a relatively high temperature stream, and when cooled in the first heat exchanger 10, the waste heat can be reused to enable more efficient use of energy.

[0045] According to the present invention, the first heat exchanger 10 may be a steam generator, and heat can be stably recovered through the steam generator. For example, the first degassed solution stream 310 may be used to produce low-pressure steam by exchanging heat with low-temperature steam through the first heat exchanger 10, which is a steam generator. For another example, the first degassed solution stream 310 may be used to exchange heat with a bottom discharge stream of an aldol purification column in which an aldol purification process is performed, and a portion of the bottom discharge stream of the aldol purification column may be refluxed to the aldol purification column to increase the temperature of the aldol purification column. In this case, the first heat exchanger 10 may be a reboiler of one or more aldol purification columns in which the aldol purification process is performed.

[0046] On the other hand, in the case where a heat exchanger is not provided downstream of the flash drum 300 as in the present invention, but is provided upstream of the flash drum 300, i.e., downstream of the first hydrogenation reactor 100, if the hydrogen fraction in the stream supplied to the heat exchanger is high, the temperature in the heat exchanger must be further reduced for a stable process flow, and therefore a cooler can be used as the heat exchanger. In this case, since a cooler is used as the heat exchanger, it may be impossible to reuse waste heat from the cooler.

[0047] Meanwhile, the method for producing neopentyl glycol of the present invention may include circulating a portion of the reduced temperature first degassed solution stream to the first hydrogenation reactor as a first branch stream, and supplying the remainder to the second hydrogenation reactor as a second branch stream.

[0048] Specifically, a part of the first degassed solution stream 310 whose temperature has been stably reduced in the first heat exchanger 10 is branched into a first branch stream 11, and the remainder is branched into a second branch stream 12. The first branch stream 11 is circulated to the first hydrogenation reactor, and the second branch stream 12 is introduced into the second hydrogenation reactor 200.

[0049] Here, the mass flow ratio of the flow rate of the first branch stream 11 to the flow rate of the second branch stream 12 may be 3:1 to 7:1, specifically 4:1 to 6:1. By controlling the mass flow ratio within this range, the two streams branched through the first heat exchanger 10, i.e., the first branch stream 11 and the second branch stream 12, can be supplied to the first hydrogenation reactor 100 and the second hydrogenation reactor 200 at an appropriate ratio, respectively. This allows the temperature increased by the hydrogenation reaction in the process to be stably reduced in the heat exchanger.

[0050] More specifically, if the mass flow ratio is less than 3:1, the flow rate of the second branch stream 12 becomes relatively high, and the temperature increases excessively during the hydrogenation reaction in the second hydrogenation reactor 200 to which the second branch stream 12 is supplied, making it difficult to reduce the temperature in the fourth heat exchanger 40. On the other hand, if the mass flow ratio exceeds 7:1, the flow rate of the first branch stream 11 increases excessively, and after the hydrogenation reaction in the first hydrogenation reactor 100, the gas phase and liquid phase are separated in the flash drum 300 and the temperature is reduced in the first heat exchanger 10, resulting in excessive energy consumption.

[0051] In addition, the temperature of the first branch stream 11 may be 110°C to 140°C. Specifically, the temperature of the first branch stream 11 may be 120°C to 135°C or 125°C to 135°C. Since the first branch stream 11 is supplied to the first hydrogenation reactor 100 via the second heat exchanger 20 at a temperature within the above range, even if the temperature increases due to the hydrogenation reaction, the first reaction product is introduced into the first hydrogenation reactor 100 in a cooled state, so that the temperature of the first reaction product does not increase excessively. Therefore, the temperature can be reduced. R In this case, accidents such as fires and explosions caused by runaway reactions can be prevented.

[0052] In addition, the first branched stream 11 is mixed with the feed stream 1 to form a mixed stream 4, and the mixed stream 4 may be supplied to the first hydrogenation reactor 100 via the second heat exchanger 20. Specifically, by reducing the temperature of the mixed stream 4 again in the second heat exchanger 20, the lower discharge stream 110 of the first hydrogenation reactor 100 may not be discharged at an excessively high temperature due to the hydrogenation reaction occurring in the first hydrogenation reactor 100.

[0053] Meanwhile, the second branch stream 12 including the first degassed solution stream whose temperature has been reduced by the first heat exchanger 10 may be supplied to the second hydrogenation reactor 200 in a state where it is again reduced in temperature through the third heat exchanger 30.

[0054] A method for producing neopentyl glycol according to one embodiment of the present invention may include obtaining a second reaction product containing NPG by hydrogenating hydrogen contained in the top discharge stream 320 of the flash drum with HPA contained in the second branch stream 12 in the second hydrogenation reactor 200. Here, the second branch stream 12 may further contain NPG produced in the first hydrogenation reactor 100.

[0055] Meanwhile, the operating temperature of the second hydrogenation reactor 200 may be 100°C to 200°C, specifically 130°C to 180°C, or 150°C to 170°C, and the operating pressure may be 20 kg / cm 2 ~50kg / cm 2 , specifically 30 kg / cm 2 ~45kg / cm 2 , 35kg / cm 2 ~45kg / cm 2 The operating conditions of the second hydrogenation reactor 200 may be the same as the operating conditions of the first hydrogenation reactor 100.

[0056] Meanwhile, similar to the hydrogenation reaction in the first hydrogenation reactor 100, NPG can also be produced in the second hydrogenation reactor 200 by the hydrogenation reaction of the HPA and hydrogen. A second reaction product containing the NPG produced in this manner can be obtained, and the second reaction product can be supplied to the degassing unit 400 via the fourth heat exchanger 40 as the lower discharge stream 210 of the second hydrogenation reactor. By reducing the temperature of the second reaction product in the fourth heat exchanger 40, the pressure in the degassing tower of the degassing unit 400, which will be described later, can be reduced, allowing for smoother degassing.

[0057] According to one embodiment of the present invention, the second reaction product can be supplied to a degassing unit 400, and a second degassed solution stream 410 from which hydrogen has been removed can be introduced into the neopentyl glycol purification process. Here, the hydrogen may be hydrogen that has not been hydrogenated with HPA in the second hydrogenation reactor 200, and the hydrogen can be further degassed in the degassing unit 400. Degassing is performed in the degassing unit 400, and a degassing unit upper outlet stream 420 containing the hydrogen and a second degassed solution stream 410 containing NPG can be obtained. The degassing unit upper outlet stream 420 can be supplied to a compressor 60, and the second degassed solution stream 410 can be introduced into the NPG purification process described below.

[0058] Here, the degassing unit 400 may include one or more degassing towers to perform degassing. For example, the second reaction product may be first degassed in a first degassing tower, and the stream discharged from the upper part of the first degassing tower may be degassed again. The degassed stream may be supplied to the first hydrogenation reactor 100 via a compressor 60. A portion of the stream discharged through the compressor 60 may be branched, cooled through a heat exchanger, and circulated to a stage upstream of the compressor 60. Meanwhile, the stream discharged from the lower part of the first degassing tower may also be degassed again, and the stream from which hydrogen has been degassed may be subjected to an NPG purification process.

[0059] Then, the method for producing neopentyl glycol according to one embodiment may include introducing the second reaction product into a neopentyl glycol purification process to obtain neopentyl glycol.

[0060] Specifically, an NPG purification step can be performed to obtain NPG from the second degassed solution stream 410 containing NPG. In addition, the second degassed solution stream 410 can further contain HPNE, a catalyst, and an extractant.

[0061] The neopentyl glycol purification step of the present invention can be a step of obtaining neopentyl glycol by distilling the second degassed solution stream 410. Specifically, the NPG purification step can be a step of distilling the second degassed solution stream 410 to separate it into the catalyst, the extractant, HPNE, and NPG, and obtaining the separated NPG as the target product.

[0062] On the other hand, as described above, HPNE separated in the NPG purification step is a by-product of the target product, NPG. By subjecting the HPNE-containing stream separated in the NPG purification step to an HPNE purification step, not only can NPG that was not recovered in the NPG purification step be further obtained, but also the HPNE, which is a high-value-added product in itself, can be recovered and used as a product.

[0063] For example, in the HPNE purification process, HPNE and a portion of NPG can be separated by distilling the HPNE-containing stream separated in the NPG purification process. That is, the portion of NPG that was not obtained in the NPG purification process can be recovered from the HPNE purification process, thereby further increasing the NPG recovery rate. Furthermore, the HPNE can be used as a raw material in other processes, for example, as a main raw material for polyester synthesis and coating, and the HPNE purification process according to the present invention can improve the economy in terms of raw material utilization.

[0064] Meanwhile, according to one embodiment of the present invention, the catalyst and extractant separated in the NPG purification process can be subjected to an extractant purification process. A fraction containing the catalyst and a fraction containing the extractant can be separated by distillation in the extractant purification process. Here, the catalyst can be a small amount of catalyst that is not separated in the aldol purification process. The catalyst in the extractant purification process can be separated and recycled to the aldol purification process, thereby recovering the catalyst, e.g., TEA, in the system.

[0065] Meanwhile, the extractant separated in the extractant purification step may be the unreacted extractant from the aldol extraction step, and this can be recycled to the aldol extraction step, whereby the extractant, e.g., 2-EH, can be separated, recovered, and reused.

[0066] The present invention will be described in more detail with reference to the following examples. However, the following examples are for illustrative purposes only, and it will be apparent to those skilled in the art that various changes and modifications can be made within the scope and technical concept of the present invention, and the scope of the present invention is not limited to these examples.

[0067] Example

[0068] Reference example The neopentyl glycol (NPG) manufacturing process was simulated using an Aspen Plus simulator manufactured by Aspen Corporation, following the process flow illustrated in FIG.

[0069] A feed stream 1 containing hydroxypivaldehyde (HPA) and a hydrogen supply stream 3 containing compressed hydrogen were each supplied to a first hydrogenation reactor 100 and hydrogenated to obtain a first reaction product containing neopentyl glycol. The first hydrogenation reactor 100 was operated at a temperature of 160°C and a pressure of 40 kg / cm. 2 The fraction of hydrogen contained in the first reaction product (hydrogen fraction in the first reaction product) relative to the total weight of the first reaction product was 17 ppm.

[0070] The first reaction product was supplied to a flash drum 300 to obtain a top discharge stream 320 of the flash drum containing hydrogen and a first degassed solution stream 310 from which the hydrogen had been degassed. The hydrogen content in the first degassed solution stream 310 (heat exchanger inlet hydrogen fraction) was 17 ppm.

[0071] Then, the top discharge stream 320 of the flash drum was supplied to the second hydrogenation reactor 200, and the first degassed solution stream 310 was supplied to the first heat exchanger 10 to be cooled to 130°C. The first heat exchanger 10 was a steam generator. A portion of the cooled first degassed solution stream was circulated to the first hydrogenation reactor 100 as a first branch stream 11, and the remainder was supplied to the second hydrogenation reactor 200 as a second branch stream 12.

[0072] Specifically, the first branch stream 11 was mixed with the feed stream 1 to form a mixed stream 4, and the mixed stream 4 was supplied to the first hydrogenation reactor 100 via a second heat exchanger 20. Meanwhile, the second branch stream 12 was supplied to the second hydrogenation reactor 200 after being cooled again via a third heat exchanger 30.

[0073] In the second hydrogenation reactor 200, the hydrogen contained in the top discharge stream 320 of the flash drum and the HPA contained in the second branch stream 12 were hydrogenated to obtain a second reaction product containing neopentyl glycol.

[0074] The second reaction product was supplied as the bottom discharge stream 210 from the second hydrogenation reactor to the degassing unit 400 via the fourth heat exchanger 40. The temperature of the stream passing through the fourth heat exchanger 40 was 40°C. The second degassed solution stream 410, from which hydrogen was further removed in the degassing unit 400, was introduced into a neopentyl glycol purification process to obtain neopentyl glycol.

[0075] Example 2 Example 2 is Reference example The reactivity in the first hydrogenation reactor was controlled to adjust the ratio of hydrogen contained in the first reaction product to the total weight of the first reaction product (hydrogen fraction in the first reaction product) to 1%. Also, the hydrogen content in the first degassed solution stream 310 (heat exchanger inlet hydrogen fraction) was 17 ppm.

[0076] Comparative Example Comparative Example 1 The neopentyl glycol (NPG) manufacturing process was simulated using an Aspen Plus simulator manufactured by Aspen Corporation, following the process flow illustrated in FIG.

[0077] In Comparative Example 1, the bottom discharge stream 110 from the first hydrogenation reactor containing the first reaction product was supplied to a cooler 50, where it was cooled from 160°C to 130°C, and then supplied to a flash drum 300.

[0078] A first degassed solution stream 310 from which gaseous hydrogen has been removed in the flash drum was obtained, and a part of the first degassed solution stream 310 was mixed with a feed stream as a first branch stream 11 to form a mixed stream 4, which was circulated to a first hydrogenation reactor 100 via a heat exchanger 20. Reference example NPG was produced using the same process flow.

[0079] As a result, the hydrogen fraction contained in the first reaction product (hydrogen fraction in the first reaction product) relative to the total weight of the first reaction product was 17 ppm. Since the first reaction product was supplied to the cooler 50, the hydrogen fraction at the heat exchanger (cooler) inlet was also 17 ppm.

[0080] Comparative Example 2 In Comparative Example 2, the reactivity in the first hydrogenation reactor was controlled so that the ratio of hydrogen contained in the first reaction product to the total weight of the first reaction product (hydrogen fraction in the first reaction product) was adjusted to 1% compared to Comparative Example 1. Since the first reaction product was supplied to the cooler 50, the hydrogen fraction at the heat exchanger (cooler) inlet was also 1%.

[0081] Table 1 below shows the hydrogen fraction in the first reaction product, the heat exchanger inlet hydrogen fraction, the heat exchanger inlet hydrogen fraction (vapor fraction), the volume increase rate, and the heat recovery amount for the examples and comparative examples.

[0082] The heat exchanger inlet hydrogen fraction (vapor fraction) represents the ratio of the mass flow rate of the vapor components contained in the stream supplied to the heat exchanger to the total mass flow rate of the stream supplied to the heat exchanger, where the heat exchanger may be the first heat exchanger in the examples and the cooler in the comparative examples.

[0083] [Table 1]

[0084] Referring to Table 1, in the example, the first reaction product was supplied to a flash drum to remove gaseous hydrogen, and the resulting mixture was supplied to the first heat exchanger. It was confirmed that there was no vapor fraction in the stream input to the first heat exchanger. It was also confirmed that waste heat could be recovered by using the first heat exchanger (steam generator).

[0085] The aforementioned Reference example In the case where the hydrogen fraction contained in the first reaction product was 17 ppm, which was a very small amount, and since the hydrogen existed in a liquid phase, it was confirmed that the hydrogen fraction in the stream introduced into the heat exchanger via the flash drum was the same as the hydrogen fraction contained in the first reaction product.

[0086] In Example 2, the hydrogen fraction contained in the first reaction product was 1%. Reference example In this case, the hydrogen fraction is relatively high compared to the first heat exchanger. When the hydrogen fraction is relatively high, both liquid and vapor phase hydrogen can exist. Therefore, by supplying the first reaction product to a flash drum and removing the vapor phase hydrogen, it was confirmed that there was no vapor fraction in the stream input to the first heat exchanger. In addition, it was confirmed that the hydrogen input to the first heat exchanger was in liquid phase, and the hydrogen fraction in the stream input to the first heat exchanger was 17 ppm.

[0087] On the other hand, in the comparative example, the first reaction product is first supplied to a cooler to reduce the temperature, and then supplied to a flash drum. Reference example As shown above, the proportion of hydrogen in the first reaction product is very small, so no gaseous hydrogen exists, but it was not possible to recover waste heat by providing a cooler to reduce the temperature of the first reaction product.

[0088] In Comparative Example 2, as in Example 2, the hydrogen fraction in the first reaction product was high, and as described above, both liquid and gaseous hydrogen were present. Because this first reaction product was supplied to the cooler, the vapor fraction in the stream (first reaction product) input to the cooler was confirmed to be 0.32, and the volume increase ratio was confirmed to be 4.5. The volume increase ratio represents the ratio of the volume of the stream supplied to the heat exchanger (cooler) when the heat exchanger inlet hydrogen fraction was 17 ppm (Example and Comparative Example 1) and when the heat exchanger inlet hydrogen fraction was 1% (Comparative Example 3). In other words, it was confirmed that the presence of a vapor fraction in the stream supplied to the cooler in Comparative Example 2 increased the amount of vapor hydrogen, and the volume of the stream supplied to the cooler increased compared to Example and Comparative Example 1.

Claims

1. supplying a feed stream containing hydroxypivaldehyde and a hydrogen supply stream to a first hydrogenation reactor and hydrogenating them to obtain a first reaction product containing neopentyl glycol; feeding the first reaction product to a flash drum to obtain a top effluent stream containing hydrogen and a first degassed solution stream from which the hydrogen has been degassed; feeding the top discharge stream of the flash drum to a second hydrogenation reactor; feeding the first degassed solution stream to a first heat exchanger to reduce the temperature; circulating a portion of the reduced temperature first degassed solution stream to the first hydrogenation reactor as a first branch stream and supplying the remainder to the second hydrogenation reactor as a second branch stream; hydrogenating the hydrogen contained in the top discharge stream of the flash drum with the hydroxypivaldehyde contained in the second branched stream in the second hydrogenation reactor to obtain a second reaction product containing neopentyl glycol; and introducing the second reaction product into a neopentyl glycol purification step to obtain neopentyl glycol.

2. 2. The method for producing neopentyl glycol according to claim 1, further comprising the steps of supplying the second reaction product to a degassing section and introducing a second degassed solution stream from which hydrogen has been removed into the neopentyl glycol purification step.

3. 2. The method for producing neopentyl glycol according to claim 1, wherein the first branch stream is mixed with the feed stream to form a mixed stream, and the mixed stream is supplied to a first hydrogenation reactor via a second heat exchanger.

4. 2. The method for producing neopentyl glycol according to claim 1, wherein the temperature of the first branch stream is 110°C to 140°C.

5. 2. The method for producing neopentyl glycol according to claim 1, wherein the first degassed solution stream is heat exchanged with low temperature steam or with a bottom effluent stream of an aldol purification column via a first heat exchanger.

6. 2. The method for producing neopentyl glycol according to claim 1, wherein the hydrogen content of the liquid phase in the first degassed solution stream is 30 ppm or less.

7. 3. The method for producing neopentyl glycol according to claim 2, wherein a flow rate ratio of the first branch stream to the second branch stream is 3:1 to 7:

1.

8. The hydroxypivaldehyde-containing feed stream comprises: an aldol reaction step of obtaining a condensation reaction product by aldol condensation reaction of an aqueous formaldehyde solution with isobutyraldehyde in the presence of a catalyst; an aldol extraction step in which the condensation reaction product is contacted with an extractant to obtain an extract and a raffinate; a saponification reaction step in which the raffinate is reduced to a catalyst; 2. The method for producing neopentyl glycol according to claim 1, wherein the neopentyl glycol is obtained from a feedstream production process that includes an aldol purification process in which the catalyst and the extract are distilled to separate a fraction containing hydroxypivaldehyde as a feedstream.

9. 9. The method for producing neopentyl glycol according to claim 8, wherein the catalyst comprises triethylamine (TEA).

10. The method for producing neopentyl glycol according to claim 8, wherein the extractant includes 2-ethylhexanol (2-EH).

11. 2. The method for producing neopentyl glycol according to claim 1, wherein the first heat exchanger is a steam generator.

12. 3. The method for producing neopentyl glycol according to claim 2, wherein the neopentyl glycol purification step comprises distilling the second degassed solution stream to obtain neopentyl glycol.

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