Neopentyl glycol wastewater treatment method

Abstract

The present invention provides a method for treating wastewater from neopentyl glycol, the method comprising the steps of recovering wastewater containing a catalyst from one or more of an aldol purification step, a neopentyl glycol purification step, and an extractant recovery step, and supplying the recovered wastewater to a volatile organic compound separation tower; obtaining an upper discharge stream containing the catalyst and a lower discharge stream containing the wastewater from which the catalyst has been removed from the volatile organic compound separation tower; and supplying the lower discharge stream to a wastewater treatment system to treat the wastewater.

Description

[Technical Field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0114489 filed on September 8, 2022, and Korean Patent Application No. 10-2023-0112002 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 treating wastewater produced from neopentyl glycol, and more particularly to a method for treating wastewater produced during the production of neopentyl glycol. [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, formaldehyde is used in the form of an aqueous solution to ensure reactivity and fluidity, and therefore contains a large amount of water. Therefore, the water contained in the formaldehyde aqueous solution is treated as wastewater after the aldol condensation reaction. The wastewater contains catalyst that has not been separated in the aldol purification process, and since the catalyst contains amine groups, it causes the generation of nitrogen oxides (NOx).

[0005] That is, when treating the wastewater, environmental pollution problems occur, and the catalyst that has been added is discarded by being washed away in the wastewater, and new catalyst must be continuously added, which increases production costs.

[0006] Therefore, there is a need to introduce a process that can recover and reuse the catalyst from the wastewater, which is environmentally friendly and economically efficient. Summary of the Invention [Problem to be solved by the invention]

[0007] The problem to be solved by the present invention is to provide a method for treating neopentyl glycol wastewater, which can obtain a larger amount of neopentyl glycol, and which is environmentally friendly and can further improve the economic efficiency of the entire process, in order to solve the problems mentioned in the background of the invention above. [Means for solving the problem]

[0008] According to one embodiment of the present invention for solving the above-mentioned problems, the present invention provides a process for producing a first reaction product containing hydroxypivaldehyde by aldol condensation reaction of an aqueous formaldehyde solution with isobutyraldehyde in the presence of a catalyst; an aldol extraction process for contacting the first reaction product with an extractant to produce a raffinate containing a catalyst salt and an extract containing hydroxypivaldehyde; an aldol purification process for distilling the extract to separate it into wastewater containing the catalyst, unreacted isobutyraldehyde, the catalyst, and hydroxypivaldehyde; a hydrogenation process for hydrogenating the hydroxypivaldehyde separated in the aldol purification process to produce a second reaction product containing neopentyl glycol; and a process for distilling the second reaction product to separate it into the extractant, the catalyst, the wastewater containing the catalyst, and neopentyl glycol. and a neopentyl glycol purification step of separating the catalyst-containing wastewater from the aldol purification step, the neopentyl glycol purification step, and the extractant recovery step, and supplying the recovered catalyst-containing wastewater to a volatile organic compound separation column; distilling the catalyst-containing wastewater in the volatile organic compound separation column to obtain an upper discharge stream containing the catalyst and a lower discharge stream containing the wastewater from which the catalyst has been removed; and supplying the lower discharge stream from the volatile organic compound separation column to a wastewater treatment system to treat the wastewater. [Effects of the Invention]

[0009] According to the method for treating wastewater containing neopentyl glycol of the present invention, the catalyst can be separated by supplying the wastewater containing the catalyst to a volatile organic compound separation column and distilling it. By supplying the wastewater from which the catalyst has been separated to a downstream wastewater treatment system in this way, the generation of nitrogen oxides (NOx) can be significantly reduced, thereby reducing environmental pollution.

[0010] In addition, the catalyst separated in the volatile organic compound separation column can be recycled to the aldol purification step and reused as a raw material in the aldol reaction step, thereby reducing the production cost for producing neopentyl glycol and improving the overall process economy. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a process diagram showing a method for treating wastewater generated during the production process of neopentyl glycol according to one embodiment of the present invention. [Figure 2] 1 is a process flow chart illustrating a method for producing neopentyl glycol according to one embodiment of the present invention. [Figure 3] FIG. 2 is a process diagram showing a method for treating wastewater generated during the production process of neopentyl glycol according to a comparative example of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] 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.

[0013] 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 simultaneously refer to the fluid itself flowing in a pipe connecting each device and the flow of the fluid. Furthermore, the fluid can refer to gas or liquid, and does not exclude cases where the fluid contains solid components.

[0014] Meanwhile, in the present invention, in apparatuses such as separation towers, extraction towers, purification towers, distillation towers or distillation columns, and recovery towers, the "lower part" of the apparatus means, unless otherwise specified, a point 95% to 100% of the height from the top of the apparatus downward, specifically the lowest end (bottom). Similarly, the "upper part" of the apparatus means, unless otherwise specified, a point 0% to 5% of the height from the top of the apparatus downward, specifically the highest part (top).

[0015] Meanwhile, in the present invention, in apparatuses such as a separation column, an extraction column, a purification column, a distillation column, and a recovery column, 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.

[0016] The present invention will now be described in more detail to facilitate understanding of the present invention.

[0017] According to one embodiment of the present invention, the process includes an aldol reaction step in which an aqueous formaldehyde solution and isobutyraldehyde undergo an aldol condensation reaction in the presence of a catalyst to obtain a first reaction product containing hydroxypivaldehyde; an aldol extraction step in which the first reaction product is contacted with an extractant to obtain a raffinate containing a catalyst salt and an extract containing hydroxypivaldehyde; an aldol purification step in which the extract is distilled to separate wastewater containing the catalyst, unreacted isobutyraldehyde, the catalyst, and hydroxypivaldehyde; a hydrogenation step in which the hydroxypivaldehyde separated in the aldol purification step is hydrogenated to obtain a second reaction product containing neopentyl glycol; and a distillation step in which the second reaction product is separated into the extractant, the catalyst, the wastewater containing the catalyst, and neopentyl glycol. and a neopentyl glycol purification step in which the separated extractant and catalyst are supplied to an extractant recovery tower where an extractant recovery step is performed to separate catalyst-containing wastewater and obtain the separated neopentyl glycol. The method includes the steps of recovering catalyst-containing wastewater from one or more of the aldol purification step, the neopentyl glycol purification step, and the extractant recovery step and supplying the recovered catalyst-containing wastewater to a volatile organic compound separation tower, distilling the catalyst-containing wastewater in the volatile organic compound separation tower to obtain an upper discharge stream containing the catalyst and a lower discharge stream containing wastewater from which the catalyst has been removed, and supplying the lower discharge stream from the volatile organic compound separation tower to a wastewater treatment system to treat the wastewater.

[0018] More specifically, the present invention will be described in detail with reference to FIG.

[0019] First, a method for treating neopentyl glycol wastewater according to one embodiment of the present invention may include an aldol reaction step 50 in which an aqueous formaldehyde (FA) solution and isobutylaldehyde (IBAL) undergo an aldol condensation reaction in the presence of a catalyst to obtain a first reaction product including hydroxypivaldehyde (HPA).

[0020] Specifically, the aldol reaction step 50 can be performed in an aldol reactor where the aldol condensation reaction occurs. Since the formaldehyde is used in an aqueous solution phase to ensure reactivity and fluidity, it can contain a large amount of water. This aqueous formaldehyde solution can contain 40 to 64 wt %, more specifically 45 to 55 wt %, of water based on the weight of the entire aqueous formaldehyde solution. Furthermore, methanol can be further included to prevent polymerization of formaldehyde. In this case, the content of the methanol can be 0.1 to 15 wt %, more specifically 0.1 to 5 wt %, based on the weight of the entire aqueous formaldehyde solution.

[0021] Here, formalin can be used as the formaldehyde aqueous solution, and the use of formaldehyde with a concentration of 35 to 45% by weight can be effective in reducing wastewater.

[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 is most efficient in the aldol condensation reaction and may be used as the catalyst.

[0023] Specifically, the aldol condensation reaction temperature may be 70° C. to 100° C., and the aldol condensation reaction time may be 0.1 hours to 3 hours in the aldol condensation reaction performed in the aldol reaction step 50. Under these aldol condensation reaction conditions, the aldol condensation reaction of the aqueous formaldehyde solution and IBAL is carried out in the presence of a catalyst, thereby producing a catalyst salt and HPA.

[0024] Here, the catalyst salt may be produced by reacting formic acid generated in a Cannizzaro side reaction occurring in the aldol condensation reaction with the catalyst.

[0025] Furthermore, hydroxypivalic acid-neopentylglycol ester (HPNE) can be produced by the Tishchenko reaction, which is another side reaction of the aldol condensation reaction.

[0026] Thus, in the aldol reaction step 50, a first reaction product containing the catalyst salt, HPNE, and HPA can be obtained, and the first reaction product can be supplied to an aldol extraction column in which an aldol extraction step 150 is carried out.

[0027] A method for treating neopentyl glycol wastewater according to one embodiment of the present invention can include an aldol extraction step 150 in which the first reaction product is contacted with an extractant to obtain a raffinate containing catalyst salts and an extract containing hydroxypivaldehyde.

[0028] Specifically, in the aldol extraction step 150, the first reaction product containing the catalyst salt, HPNE, and HPA is contacted with an extractant to obtain an organic phase extract containing unreacted IBAL, the extractant, and HPA, and a liquid phase raffinate containing the catalyst salt. Here, the unreacted IBAL may be IBAL that has not undergone the aldol condensation reaction in the aldol reaction step 50. The extract may be supplied to an aldol purification column where the aldol purification step 200 is performed, and the raffinate may be supplied to a catalytic conversion reactor where the catalytic conversion reaction step 60 is performed.

[0029] Here, the extractant may be an aliphatic alcohol, preferably 2-ethylhexanol (2-EH). Since HPA contained in the first reaction product is soluble in 2-EH, it can be preferably used in the aldol extraction step 150 using a liquid-liquid contact extraction apparatus.

[0030] Meanwhile, the operating temperature of one or more aldol extraction towers in which the aldol extraction step 150 is performed may be 40° C. to 90° C. Operating the aldol extraction towers at a temperature within this range may facilitate phase separation into an organic phase and a liquid phase.

[0031] The method for treating neopentyl glycol wastewater according to one embodiment of the present invention may include a catalytic conversion reaction step 60 in which the raffinate obtained in the aldol extraction step 150 is subjected to a catalytic conversion reaction to convert the catalyst salt into a catalyst.

[0032] In the catalytic conversion reactor where the catalytic conversion reaction step 60 is performed, the extract containing the catalytic salt is subjected to a catalytic conversion reaction to convert the catalytic salt into a catalyst. The catalytic conversion reaction performed in the catalytic conversion reactor can be carried out by reacting the catalytic salt with a strong inorganic base such as sodium hydroxide (NaOH), which is added separately, thereby allowing the converted catalyst to be efficiently reused.

[0033] The converted catalyst may be subjected to a catalyst recovery process 700, in which the converted catalyst is distilled in a catalyst recovery tower to separate the catalyst from wastewater, and the separated catalyst may be recycled to the aldol purification process 200.

[0034] On the other hand, if the separated catalyst is supplied to an aldol reactor where the aldol reaction process 50 is performed, excessive side reactions may occur in the aldol reaction process 50, resulting in the production of large amounts of high-boiling point nitrogen compounds as by-products. These may then flow into a volatile organic compound (VOC) separation tower (described below), causing an increase in nitrogen oxides (NOx). Therefore, by circulating the separated catalyst to the aldol purification process 200 rather than immediately supplying it to the aldol reactor where the aldol reaction process 50 is performed, the side reactions in the aldol reaction process 50 can be further reduced, reducing the production of by-products and thereby further minimizing the generation of NOx. Furthermore, the separated catalyst can be purified in the aldol purification tower where the aldol purification process 200 is performed, allowing it to be reused as a higher-purity catalyst.

[0035] Meanwhile, the present invention may further include a step of supplying the wastewater separated from the catalyst recovery process 700 to a VOC separation tower. Thus, if the separated wastewater contains a portion of the catalyst that was not separated in the catalyst recovery process 700, the VOC separation tower can recover a portion of the catalyst contained in the separated wastewater.

[0036] The method for treating neopentyl glycol wastewater according to one embodiment of the present invention may include an aldol purification step 200 in which the extract is distilled to separate the wastewater containing the catalyst, unreacted isobutyraldehyde and catalyst, and hydroxypivaldehyde.

[0037] Specifically, the aldol purification step 200 may be a step of distilling the catalyst recovered in the catalyst recovery step 700 and the extract separated in the aldol extraction step 150 to separate them into catalyst-containing wastewater, unreacted IBAL and the catalyst, and HPA and the extractant. Here, the distillate to be distilled in the aldol purification step 200 may further include the catalyst recovered in the catalyst recovery step 700 and the extract separated in the aldol extraction step 150, as well as the catalyst separated in the extractant recovery step 500 (described below) and the top discharge stream of a volatile organic compound separation tower.

[0038] More specifically, the aldol purification step 200 can be performed using two or more columns, one or more of which can include an aldol purification column and the remaining one or more can include a wastewater separation column.

[0039] First, the aldol purification column is one aldol purification column Yes In this case, unreacted IBAL and the catalyst can be separated from the top of the single aldol purification column, and HPA and the extractant can be separated from the bottom. a In this case, the process may be carried out through 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. In addition, the unreacted IBAL and / or catalyst separated from the top of the one or more aldol purification columns may be separated together with water.

[0040] Meanwhile, the one or more wastewater separation towers can function to separate wastewater (water) from the unreacted IBAL, catalyst, HPA, and extractant. Therefore, the stream supplied to the wastewater separation tower can be a stream containing water separated in one or more aldol purification towers. Furthermore, the wastewater recovered from the wastewater separation tower can be supplied to a wastewater tank 10, which will be described later. Here, the wastewater supplied to the wastewater tank 10 contains a small amount of catalyst and unreacted IBAL that was not separated in the wastewater separation tower.

[0041] According to the present invention, the aldol purification process 200 can recycle the unreacted IBAL and catalyst separated in the aldol purification process 200 to the aldol reaction process 50. This recycles the catalyst and IBAL used in the aldol reaction process 50, thereby reducing the amount of raw materials newly input and reducing production costs used in the process.

[0042] The method for treating neopentyl glycol wastewater according to one embodiment of the present invention may include a hydrogenation step 70 in which the hydroxypivaldehyde separated in the aldol purification step 200 is hydrogenated to obtain a second reaction product containing neopentyl glycol.

[0043] In the hydrogenation process 70, a second reaction product containing NPG is obtained by hydrogenating hydrogen introduced separately from the HPA separated in the aldol purification process 200. Here, the hydrogenation may be carried out at a hydrogen pressure of 100 to 1500 psig (pounds per square inch gauge pressure) (0.69 to 10.3 MPaG) and a reaction temperature of 100°C to 200°C.

[0044] The hydrogenation reaction can be carried out in the presence of a hydrogenation catalyst. A nickel catalyst or a copper-based catalyst can be used as the hydrogenation catalyst. The nickel catalyst can be present in an amount of 2 to 10 wt % based on the weight of the HPA. An example of the copper-based catalyst is a CuO / BaO / SiO catalyst. The CuO / BaO / SiO catalyst can be a (CuO)x(BaO)y(SiO)z catalyst (x, y, and z are in weight %, 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 %) relative to the total sum of x, y, and z (100 wt %). Within this range, the hydrogenation catalyst exhibits excellent performance and a long life.

[0045] In this way, NPG can be produced by the hydrogenation reaction of hydrogen and HPA. Therefore, a second reaction product containing a catalyst, an extractant, the NPG, and HPNE can be obtained in the hydrogenation reaction step 70. Here, the HPNE can be produced as a by-product of the aldol condensation reaction in the aldol reaction step 50. Then, the second reaction product is purified in the NPG purification step 300 to obtain the desired product, neopentyl glycol.

[0046] A method for treating neopentyl glycol wastewater according to one embodiment of the present invention may include a neopentyl glycol purification step 300, in which the second reaction product is distilled to separate it into an extractant and a catalyst, wastewater containing the catalyst, and neopentyl glycol, and the separated extractant and catalyst are supplied to an extractant recovery column where an extractant recovery step 500 is performed to separate the wastewater containing the catalyst, and the separated neopentyl glycol is obtained.

[0047] Specifically, the NPG purification step 300 can be a step of distilling the second reaction product to separate it into wastewater containing the catalyst, the extractant and catalyst, and NPG. The separated extractant and catalyst can be introduced into an extractant recovery step 500, which will be described later, and the NPG can be obtained as the target product in the NPG purification step 300.

[0048] Additionally, the NPG purification process 300 can further separate HPNE from the second reaction product, and the HPNE-containing stream can be introduced into a hydroxypivalic acid-neopentyl glycol ester (HPNE) purification process.

[0049] Meanwhile, the NPG purification step 300 can be performed using two or more columns, like the aldol purification step 200. At least one of the two or more columns can include an NPG purification column, and the remaining one or more can include a wastewater separation column.

[0050] First, the NPG purification tower is one NPG purification tower. Yes In this case, the extractant and catalyst can be separated from the top of the single NPG purification column, HPNE from the bottom, and NPG from the side. a In this case, the process may be carried out through one or more NPG purification columns separating the extractant at the top and one or more NPG purification columns separating the catalyst at the top. A stream containing HPNE or NPG may be separated and discharged from the bottom of the two or more NPG purification columns. In addition to the catalyst, extractant, HPNE, and NPG, a stream containing water, i.e., a wastewater stream, may be separated in one or more NPG purification columns.

[0051] Meanwhile, the one or more wastewater separation towers may function to separate the wastewater from the catalyst, extractant, HPNE, and NPG. Therefore, the stream supplied to the wastewater separation tower may be the wastewater stream separated in one or more NPG purification towers. Furthermore, the wastewater separation tower may supply the separated wastewater to a wastewater tank 10, which will be described later. Here, the wastewater may contain the catalyst that was not separated in the NPG purification tower.

[0052] On the other hand, the extractant recovery step 500 of the present invention is to recover the catalyst and extractant separated from the neopentyl glycol purification step 300. Extractant This may be a process in which the wastewater containing the catalyst, the catalyst, and the extractant are separated from each other by supplying the wastewater to a recovery column, and the catalyst is introduced into the aldol purification step 200, and the extractant is introduced into the aldol extraction step 150. Here, the catalyst may be a small amount of catalyst that is not separated in the aldol extraction step 150 and the aldol purification step 200. On the other hand, by circulating the extractant to the aldol extraction step 150, the extractant, for example, 2-EH, can be recovered and reused in the aldol extraction step 150.

[0053] More specifically, the extractant recovery step 500 can be performed using a column, i.e., an extractant recovery column. The catalyst can be separated from the top of the extractant recovery column, and the extractant can be separated from the bottom. A stream containing water, i.e., a wastewater stream, can be separated in the extractant recovery column, separate from the catalyst and extractant. The wastewater stream separated in the extractant recovery column can be supplied to a wastewater tank 10, which will be described later. The wastewater may contain a small amount of catalyst.

[0054] Meanwhile, in the HPNE purification step 400 according to one embodiment of the present invention, the HPNE-containing stream separated from the NPG purification step 300 can be distilled to separate trace amounts of NPG and HPNE. The separated trace amounts of NPG can then be recycled to the NPG purification step 300, and the HPNE can be obtained separately.

[0055] Here, the trace amount of NPG is not recovered as a product in the NPG purification step but is separated together with HPNE, and NPG can be further recovered from the HPNE purification step 400, thereby further increasing the NPG recovery rate. The separately obtained HPNE can be used in various ways, for example, as a high-value-added product and as a main raw material for polyester synthesis and coating. In this way, it can be used as a raw material in other processes, and the HPNE purification step 400 improves the economic efficiency of raw material utilization.

[0056] Hereinafter, a more detailed description will be given of one embodiment of the present invention with reference to FIG.

[0057] A method for treating NPG wastewater according to one embodiment of the present invention may include recovering catalyst-containing wastewater from one or more of the aldol purification process, the neopentyl glycol purification process, and the extractant recovery process, and supplying the recovered wastewater to a volatile organic compounds (VOC) separation tower; obtaining an upper fraction containing the catalyst and a lower fraction containing wastewater from which the catalyst has been removed in the VOC separation tower; and supplying the lower fraction to a wastewater treatment system to treat the wastewater.

[0058] First, the method for treating NPG wastewater according to one embodiment of the present invention may include recovering catalyst-containing wastewater from one or more of the aldol purification process, the neopentyl glycol purification process, and the extractant recovery process, and supplying the recovered wastewater to a VOC separation tower 100.

[0059] Specifically, wastewater separated in one or more columns in one or more of the three processes, namely the aldol purification process, the NPG purification process, and the extractant recovery process, can be introduced into the wastewater tank 10. In addition, wastewater separated from the catalyst recovery process can also be introduced into the wastewater tank 10.

[0060] In this way, the wastewater separated in multiple steps can be supplied to the wastewater tank 10 and then supplied to the VOC separation tower 100 as the wastewater tank discharge stream 11. Here, the wastewater can be derived from the water contained in the formaldehyde aqueous solution used in the aldol reaction step 50. In addition, the wastewater can contain the catalyst and unreacted IBAL that have not been separated in the aldol purification step.

[0061] As described above, the catalyst used in the present invention may be, for example, TEA, which contains amine groups and can cause the generation of nitrogen oxides (NOx). Because NOx can be harmful to the environment, it is necessary to separate the TEA to reduce the generation of NOx. Therefore, in the present invention, the catalyst can be separated through a VOC separation tower 100, and the catalyst separated from the VOC separation tower 100 can be recovered and reused.

[0062] A method for treating neopentyl glycol wastewater according to one embodiment of the present invention may include distilling the catalyst-containing wastewater in the VOC separation tower to obtain an upper discharge stream containing the catalyst and a lower discharge stream containing the wastewater from which the catalyst has been removed.

[0063] The wastewater tank discharge stream 11 can be distilled in the VOC separation tower 100 to separate it into an upper fraction containing the catalyst and a lower fraction containing wastewater from which the catalyst has been removed. As described above, by separating TEA, the catalyst of the present invention that promotes NOx production, the amine components contained in the lower fraction of the VOC separation tower can be adjusted, thereby reducing NOx production.

[0064] Meanwhile, the operating temperature of the VOC separation tower 100 may be 50° C. or higher, 60° C. or higher, or 70° C. or higher, and 160° C. or lower, 180° C. or lower, or 200° C. or lower. The operating pressure of the VOC separation tower 100 may be 0.68 kg / cm2 (66.7 kPa) or higher, 1.50 kg / cm2 (147 kPa) or higher, or 2.00 kg / cm2 (196 kPa) or higher, and 4.00 kg / cm2 (392 kPa) or lower, 4.50 kg / cm2 (441 kPa) or lower, or 5.00 kg / cm2 (490 kPa) or lower.

[0065] The top fraction of the VOC separation column 100 can be recycled to the aldol purification process via a top discharge stream 120 of the VOC separation column. The top fraction of the VOC separation column 100 contains the catalyst and unreacted IBAL, which can be reused by recycling them to the aldol purification process. In this way, recovering and reusing the catalyst reduces NOx production, making the process environmentally friendly and cost-competitive.

[0066] Meanwhile, the bottom fraction of the VOC separation tower 100 containing the catalyst-separated wastewater can be supplied to an evaporator 20 via a bottom discharge stream 110 of the VOC separation tower.

[0067] According to one embodiment of the present invention, the catalyst content in the bottom discharge stream 110 of the VOC separation tower may be 5.0 wt% or less, more specifically, 4.0 wt% or less or 3.0 wt% or less. By including the catalyst within this range, the amine components in the stream introduced into the wastewater treatment system 30 described below may be reduced, thereby reducing the generation of NOx in the wastewater treatment system 30.

[0068] According to one embodiment of the present invention, the bottom discharge stream of the VOC separation tower can be supplied to an evaporator 20 to remove sludge, and the top fraction of the evaporator from which the sludge has been removed can be supplied to the wastewater treatment system 30.

[0069] The VOC separation tower bottom discharge stream 110, which contains the wastewater from which the catalyst has been separated in the evaporator 20, can be evaporated and separated into a bottom evaporator fraction containing sludge and an top evaporator fraction containing gaseous components from which the sludge has been removed. The bottom evaporator fraction can be supplied to a sludge dryer 40 via a bottom evaporator discharge stream 21, and the top evaporator fraction can be supplied to a wastewater treatment system 30 via an top evaporator discharge stream 22.

[0070] Meanwhile, in the sludge dryer 40, the sludge contained in the lower discharge stream 21 of the evaporator can be dried and disposed of as waste or burned and used as an energy source for the process.

[0071] The method for treating wastewater containing neopentyl glycol according to one embodiment of the present invention may include supplying the bottom discharge stream from the VOC separation tower to a wastewater treatment system to treat the wastewater.

[0072] Specifically, the wastewater treatment system 30 treats the bottom discharge stream of the VOC separation tower that has passed through the evaporator 20, i.e., the top discharge stream 22 of the evaporator, to obtain a waste gas discharge stream 32 containing waste gas and a wastewater discharge stream 31 containing wastewater. Here, the waste gas may be a gas from which the amine groups have been removed.

[0073] More specifically, the wastewater treatment system is a system that performs a process to treat organic matter present in water, and a regeneration thermal oxidizer (RTO) and a DeNOx system can be used to perform the wastewater treatment system.

[0074] The regenerative incinerator is a facility that can significantly reduce the operating costs of the incinerator by incinerating gaseous components containing organic matter and then recovering the heat generated during incineration through a ceramic filler with a large surface area that can be used semi-permanently. It also reduces the operating costs of the incinerator and minimizes the installation area. Furthermore, the regenerative incinerator has the advantage of having a very high treatment efficiency of over 99% and little secondary pollution.

[0075] Meanwhile, the DeNOx system is a system that removes nitrogen oxides using selective catalytic reduction (SCR), which breaks down gaseous components, including nitrogen oxides, generated during the process into nitrogen and water vapor by passing them through a catalyst layer together with a conversion agent (ammonia or urea), and then releases them into the atmosphere.

[0076] As described above, by first removing a catalyst, such as TEA, through a VOC recovery tower and then removing the TEA that flows into the wastewater treatment system, the amount of NOx generated in the wastewater treatment system can be reduced, resulting in environmentally friendly NPG production. Furthermore, by circulating the catalyst separated and recovered in the VOC recovery tower to the aldol purification step for purification, the purified catalyst can be made suitable for reuse in the aldol reaction step 50.

[0077] As another example, the VOC separation column may be a dividing wall distillation column. When a dividing wall column (DWC) is used as the VOC separation column, a downstream evaporator and a wastewater treatment system are not required, which simplifies the process and allows for efficient process management. In addition, energy consumption due to heat integration can be reduced.

[0078] More specifically, the dividing wall distillation column is a distillation column equipped with a dividing wall, and the space defined by the dividing wall is divided into two sections, allowing the column to function as if two distillation columns were integrated into one. Therefore, the upper fraction is the catalyst and unreacted IBAL, the lower fraction is sludge, and the side fraction is wastewater.

[0079] The bottom fraction of the VOC separation tower, including the sludge, can be supplied to a sludge dryer via a bottom discharge stream of the VOC separation tower for drying, and the side fraction of the VOC separation tower 100, including the wastewater, can be discharged via a side discharge stream 130 of the VOC separation tower.

[0080] The top fraction of the VOC separation column containing the catalyst and unreacted IBAL can be recycled to the aldol purification step as the top discharge stream of the VOC separation column, as described above. The catalyst can be purified and recovered in the aldol purification step, and the recovered catalyst can be recycled to the aldol reaction step 50 and reused as a raw material for the aldol condensation reaction.

[0081] 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.

[0082] Example Example 1 A neopentyl glycol (NPG) wastewater treatment process was simulated using an Aspen Plus simulator manufactured by Aspen Corporation according to the process diagram shown in Figure 1.

[0083] In an aldol reactor, an aqueous formaldehyde solution and isobutyraldehyde were subjected to an aldol condensation reaction in the presence of a catalyst (triethylamine; TEA) to obtain a first reaction product containing hydroxypivaldehyde (aldol reaction step).

[0084] The first reaction product was contacted with an extractant (2-ethylhexanol; 2-EH) to obtain a raffinate containing catalyst salts, an extract containing hydroxypivaldehyde, and wastewater containing the catalyst (aldol extraction step).

[0085] The raffinate was subjected to a catalytic conversion reaction to convert the catalyst salt into a catalyst, thereby obtaining a converted catalyst. (Catalytic conversion reaction step) The converted catalyst was distilled in a catalyst recovery column to separate the catalyst from the wastewater containing the catalyst, and the catalyst was recovered. (Catalyst recovery step)

[0086] The catalyst separated from the catalyst recovery step and the extract obtained from the aldol extraction step were distilled in an aldol purification column where the aldol purification step was carried out, and separated into unreacted isobutyraldehyde and catalyst, wastewater containing the catalyst, and hydroxypivaldehyde. The separated unreacted isobutyraldehyde and catalyst were circulated to the aldol reaction step (aldol purification step).

[0087] On the other hand, the hydroxypivaldehyde separated from the aldol purification step was hydrogenated to obtain a second reaction product containing neopentyl glycol. (Hydrogenation Reaction Step)

[0088] The second reaction product was distilled to separate the catalyst-containing wastewater, the extractant and catalyst, neopentyl glycol, and hydroxypivalic acid-neopentyl glycol ester (HPNE), and the neopentyl glycol was obtained as a product (NPG purification step).

[0089] The extractant and catalyst separated from the NPG purification process were passed through an extractant recovery process to separate the catalyst-containing wastewater, the extractant, and the catalyst. The extractant separated from the extractant recovery process was recycled to the aldol extraction process, and the catalyst separated from the extractant recovery process was recycled to the aldol purification process.

[0090] On the other hand, the HPNE-containing stream separated from the NPG purification step was recycled to the HPNE purification step and separated into NPG and HPNE. The NPG separated from the HPNE purification step was recycled to the NPG purification step, and the HPNE was obtained separately.

[0091] Wastewater containing the catalyst was recovered from the catalyst recovery step, aldol purification step, neopentyl glycol purification step, and extractant recovery step, and introduced into a wastewater tank 10.

[0092] The catalyst-containing wastewater introduced into the wastewater tank 10 was supplied as wastewater tank discharge stream 11 to a volatile organic compound (VOC) separation tower 100. The VOC separation tower 100 separated an upper fraction containing the catalyst and a lower fraction containing the wastewater from which the catalyst had been removed. The VOC separation tower 100 was operated at a temperature of 110°C and a pressure of 1.1 kg / cm2 (108 kPa).

[0093] The upper fraction containing the catalyst was recycled to the aldol purification step via the upper discharge stream 120 of the VOC separation column, and the lower fraction containing the wastewater from which the catalyst had been removed was supplied to an evaporator 20 via the lower discharge stream 110 of the VOC separation column.

[0094] The bottom discharge stream 110 of the VOC separation tower was evaporated in the evaporator 20 to separate a bottom fraction containing sludge and an top fraction containing gaseous components separated from the sludge. The bottom fraction containing sludge was supplied to a sludge dryer 40 as a bottom discharge stream 21, and the top fraction containing gaseous components separated from the sludge was supplied to a wastewater treatment system 30 as an top discharge stream 22.

[0095] In the wastewater treatment system 30, the evaporator top discharge stream 22 is treated to separate it into waste gas and waste water, and the waste gas is discharged via a waste gas discharge stream 32 and the waste water is discharged via a waste water discharge stream 31.

[0096] Example 2 In Example 2, NPG wastewater was treated in the same process flow as in Example 1, except that the catalyst separated from the catalyst recovery step was circulated to the aldol reactor in which the aldol reaction step was carried out, rather than to the aldol purification step.

[0097] Comparative Example Comparative Example 1 A neopentyl glycol (NPG) wastewater treatment process was simulated using an Aspen Plus simulator manufactured by Aspen Corporation according to the process diagram shown in Figure 3.

[0098] In Comparative Example 1, NPG was produced using the same process flow as in Example 1, except that the VOC separation tower was not provided and the wastewater tank discharge stream 11 was supplied to the evaporator 20.

[0099] Table 1 below shows the TEA content in the feedstream, the TEA content in the wastewater treatment system, and the amount of NOx generated in the examples and comparative examples.

[0100] Specifically, the content of TEA in the wastewater treatment system may refer to the weight ratio of TEA in the stream supplied to the wastewater treatment system to the total weight of the stream (the top discharge stream of the evaporator) supplied to the wastewater treatment system.

[0101] Meanwhile, the NOx generation amount indicates the fraction of nitrogen oxides (NOx) contained in the waste gas discharge stream 32 relative to the total weight of the waste gas discharge stream 32 of the wastewater treatment system.

[0102] [Table 1]

[0103] Referring to Table 1, it was confirmed that the Example had a reduced amount of NOx generated compared to Comparative Example 1. On the other hand, it was confirmed that Comparative Example 1 had the highest amount of NOx generated because it did not have a VOC separation tower compared to the Examples.

Claims

1. an aldol reaction step in which an aqueous formaldehyde solution and isobutyraldehyde undergo an aldol condensation reaction in the presence of a catalyst to obtain a first reaction product containing hydroxypivaldehyde; an aldol extraction step in which the first reaction product is contacted with an extractant to obtain a raffinate containing catalyst salts and an extract containing hydroxypivaldehyde; an aldol purification step in which the extract is distilled to separate it into a wastewater containing the catalyst, unreacted isobutyraldehyde and the catalyst, and hydroxypivaldehyde; a hydrogenation step of hydrogenating the hydroxypivaldehyde separated in the aldol purification step to obtain a second reaction product containing neopentyl glycol; a neopentyl glycol purification step of distilling the second reaction product to separate it into an extractant and a catalyst, wastewater containing the catalyst, and neopentyl glycol, and supplying the separated extractant and catalyst to an extractant recovery column where an extractant recovery step is performed to separate the wastewater containing the catalyst, and obtaining the separated neopentyl glycol; recovering catalyst-containing wastewater from one or more of the aldol purification step, the neopentyl glycol purification step, and the extractant recovery step, and supplying the recovered wastewater to a volatile organic compound separation column; distilling the catalyst-containing wastewater in the volatile organic compound separation column to obtain a catalyst-containing top outlet stream and a catalyst-removed wastewater bottom outlet stream; and feeding the bottoms effluent stream of the volatile organic compound separation column to a wastewater treatment system to treat the wastewater; further comprising recycling the overhead effluent stream of the volatile organic compound separation column to the aldol purification step. Neopentyl glycol wastewater treatment method.

2. The aldol purification step comprises:

2. The method for treating neopentyl glycol wastewater according to claim 1, wherein the separated unreacted isobutyraldehyde and catalyst are recycled to the aldol reaction step.

3. 2. The method for treating wastewater containing neopentyl glycol according to claim 1, further comprising a catalyst conversion step of converting a catalyst salt contained in the raffinate obtained in the aldol extraction step into a catalyst.

4. 4. The method for treating neopentyl glycol wastewater according to claim 3, further comprising a catalyst recovery step of distilling the catalyst converted in the catalyst-conversion step to separate the wastewater and the catalyst, and circulating the separated catalyst to the aldol purification step.

5. 5. The method for treating wastewater from neopentyl glycol according to claim 4, further comprising the step of supplying the wastewater separated from the catalyst recovery step to a volatile organic compound separation column.

6. The extractant recovery step includes:

2. The method for treating neopentyl glycol wastewater according to claim 1, wherein the catalyst and extractant separated from the neopentyl glycol purification step are supplied to an extractant recovery column, the catalyst-containing wastewater, the catalyst, and the extractant are separated, and the catalyst is introduced into the aldol purification step and the extractant is introduced into the aldol extraction step.

7. the neopentyl glycol purification step is a step of further separating hydroxypivalic acid-neopentyl glycol ester (HPNE) from the second reaction product; 2. The method for treating neopentyl glycol wastewater according to claim 1, further comprising a hydroxypivalic acid-neopentyl glycol ester purification step in which a stream containing hydroxypivalic acid-neopentyl glycol ester (HPNE) separated from the neopentyl glycol purification step is distilled to recycle a trace amount of neopentyl glycol to the neopentyl glycol purification step, thereby obtaining hydroxypivalic acid-neopentyl glycol ester.

8. 2. The method for treating wastewater containing neopentyl glycol according to claim 1, wherein the catalyst comprises triethylamine (TEA).

9. 2. The method for treating wastewater containing neopentyl glycol according to claim 1, wherein the extractant comprises 2-ethylhexanol (2-EH).

10. 2. The method for treating wastewater containing neopentyl glycol according to claim 1, wherein the catalyst content in the bottom discharge stream of the volatile organic compound separation tower is 5.0 wt% or less.

11. 2. The method for treating wastewater containing neopentyl glycol according to claim 1, further comprising the steps of: supplying the bottom discharge stream of the volatile organic compound separation tower to an evaporator to remove sludge; and supplying the top fraction of the evaporator from which the sludge has been removed to the wastewater treatment system.

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