Method and apparatus for producing acrylic acid

Abstract

The present invention relates to a method and an apparatus for producing acrylic acid. Specifically, the present invention relates to a method for producing acrylic acid and an apparatus therefor, comprising a two-stage reactor that enables an acrylic acid yield to reach a target level.

Description

Method and device for producing acrylic acid

[0001] Cross-citation with related application(s)

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2023-0176547, filed December 7, 2023, and Korean Patent Application No. 10-2024-0177830, filed December 3, 2024, the entire contents of which are incorporated herein by reference.

[0003]

[0004] The present invention relates to a method and apparatus for producing acrylic acid. Specifically, the present invention relates to a method and apparatus for producing acrylic acid including a two-stage reactor capable of achieving a target level of acrylic acid yield.

[0005]

[0006] Acrylic acid is an organic compound that contains both carboxylic acid and an unsaturated double bond within its molecule. It has a very simple structure, can be converted into various substances, and can be polymerized, so it is used in various industrial fields.

[0007] Specifically, acrylic acid can be used as polyacrylic acid, dots, adhesives, paints, etc. required for manufacturing superabsorbent polymers, or as a raw material for manufacturing other types of acrylate monomers, or as a polymerization raw material with various other monomers such as acrylamide, acrylonitrile, styrene, and alpha olefins.

[0008] These acrylic acids are usually manufactured using propylene produced during the refining and separation process of crude oil, such as naphtha cracking.

[0009] However, with the recent increase in concerns about crude oil depletion and environmental issues, interest in methods for producing acrylic acid using environmentally friendly raw materials is growing.

[0010] In conventional methods for producing acrylic acid through the gas-phase dehydration of lactic acid over acid catalysts, numerous side reactions occur in addition to the primary reaction, acrylic acid production. Therefore, it is necessary to design appropriate reaction conditions and reactors to achieve the desired acrylic acid yield.

[0011]

[0012] The present specification provides a method for producing acrylic acid and a device therefor, which includes a two-stage reactor designed to achieve a desired yield of acrylic acid in the production of acrylic acid through a lactic acid dehydration reaction.

[0013]

[0014] The present disclosure provides an acrylic acid production device comprising a two-stage reactor for lactic acid dehydration reaction, comprising: a feed supply section for supplying lactic acid gas; a first-stage dehydration reactor filled with a catalyst for lactic acid dehydration reaction; and a second-stage dehydration reactor filled with a catalyst for lactic acid dehydration reaction, and satisfying the following mathematical expression 1.

[0015] [Mathematical Formula 1]

[0016]

[0017] In the above mathematical expression 1, L1 is the length of the first stage, and L2 is the length of the second stage.

[0018]

[0019] According to one example, the yield of acrylic acid obtained from the acrylic acid manufacturing device may be 53% or more.

[0020]

[0021] According to one example, the first stage dehydration reactor and the second stage dehydration reactor are connected by a transfer line, and the transfer line may further include a heating unit.

[0022]

[0023] Meanwhile, the present disclosure provides a method for producing acrylic acid, comprising: a first step of supplying a feed stream containing lactic acid gas molecules from a feed supply unit to the upper portion of a first-stage dehydration reactor filled with a catalyst, performing a dehydration reaction, and then discharging the stream to the lower portion; a second step of supplying a stream discharged from the lower portion of the first-stage dehydration reactor to the upper portion of a second-stage dehydration reactor filled with a catalyst, performing a dehydration reaction, and then discharging the stream to the lower portion; wherein the feed stream supplied to the upper portion of the first-stage dehydration reactor contains lactic acid gas, and satisfies the following mathematical expression 2.

[0024] [Equation 2]

[0025]

[0026] In the above mathematical expression 2, T1 is the average time that the feed stream remains in the first-stage dehydration reactor, and T2 is the average time that the stream supplied to the second-stage dehydration reactor remains in the second-stage dehydration reactor.

[0027]

[0028] According to an example, the method for producing acrylic acid may have an acrylic acid yield of 53 mol% or more.

[0029]

[0030] According to an example, the stream discharged from the bottom of the first stage dehydration reactor is transferred to the second stage dehydration reactor through a transfer line, and the temperature of the stream can be maintained at 370°C or higher and 410°C or lower during the transfer.

[0031]

[0032] In the present invention, terms such as first, second, etc. are used to describe various components, and the terms are used only for the purpose of distinguishing one component from another.

[0033] Additionally, the terms used herein are merely used to describe exemplary embodiments and are not intended to limit the present invention.

[0034] Singular expressions include plural expressions unless the context clearly indicates otherwise.

[0035] In this specification, the terms “comprise,” “include,” or “have” are intended to describe a feature, number, step, component, or combination thereof implemented, but do not exclude the possibility of one or more other features, numbers, steps, components, combinations, or additions thereof.

[0036] Additionally, in this specification, when each layer or element is referred to as being formed “on” or “over” each layer or element, it means that each layer or element is formed directly on each layer or element, or that other layers or elements may be additionally formed between each layer, on the object, or on the substrate.

[0037] The present invention is susceptible to various modifications and takes various forms. Specific embodiments are illustrated and described in detail below. However, this does not limit the invention to a specific disclosed form, but rather encompasses all modifications, equivalents, and alternatives falling within the spirit and technical scope of the present invention.

[0038]

[0039] The lactic acid dehydration gas phase reaction is generally performed by introducing vaporized lactic acid into a reactor filled with a catalyst, causing a dehydration reaction, and then discharging acrylic acid produced by the dehydration reaction from the bottom of the reactor.

[0040] The process of producing acrylic acid through the vapor-phase dehydration of lactic acid produces not only acrylic acid, the primary product of the reaction, but also numerous byproducts from side reactions. Therefore, it is necessary to design appropriate reaction conditions and a reactor to achieve the desired acrylic acid yield.

[0041]

[0042] Accordingly, the present disclosure provides a method for producing acrylic acid and a device therefor, including a two-stage reactor designed to achieve a desired yield of acrylic acid in the production of acrylic acid.

[0043] Specifically, the present disclosure provides a method for producing acrylic acid and a device therefor, including a single reactor, which obtains a desired level of acrylic acid yield by controlling the length of a catalyst stage included in a two-stage reactor or the average time that a stream remains in a reactor including a catalyst stage.

[0044]

[0045] Hereinafter, the manufacturing device of acrylic acid of the present disclosure will be examined.

[0046]

[0047] According to one aspect of the present disclosure, an acrylic acid production device can be provided, comprising a feed supply section for supplying lactic acid gas in a two-stage reactor for lactic acid dehydration reaction; a first-stage dehydration reactor filled with a catalyst for lactic acid dehydration reaction; and a second-stage dehydration reactor filled with a catalyst for lactic acid dehydration reaction (see FIG. 1).

[0048] In addition, the acrylic acid manufacturing device of the present disclosure can satisfy the following mathematical expression 1.

[0049] [Mathematical Formula 1]

[0050]

[0051] In the above mathematical expression 1, L1 is the length of the first stage dehydration reactor, and L2 is the length of the second stage dehydration reactor.

[0052] That is, in the case of an acrylic acid manufacturing device in which the length of the first stage is in the range of 0.3 to 0.6 relative to the total reaction stage length, the yield of acrylic acid obtained from the manufacturing device may be 53% or more. In this case, the yield of acrylic acid can be obtained by the following mathematical equation 3.

[0053] [Equation 3]

[0054] Acrylic acid yield (mol%) = (number of moles of acrylic acid produced in the second stage reactor / number of moles of lactic acid introduced into the first stage reactor) * 100

[0055] The number of moles of acrylic acid produced in the second stage reactor is a measurement of the number of moles of acrylic acid in the discharge stream of the second stage reactor, and the number of moles of lactic acid fed to the first stage reactor is a measurement of the number of moles of lactic acid in the feed stream fed to the first stage reactor.

[0056]

[0057] The desired acrylic acid yield of 53 mol% or more is the highest acrylic acid yield in the current process, and since the higher the acrylic acid yield, the lower the specific unit, the higher the acrylic acid yield is better. Specifically, when the acrylic acid yield increases from 50 mol% to 53 mol%, the specific unit of lactic acid decreases by about 5 to 6%. Since the specific unit of lactic acid accounts for the largest proportion of the acrylic acid manufacturing cost, improving the acrylic acid yield is very important for reducing the cost. At this time, the specific unit of lactic acid is the value obtained by dividing the total amount of lactic acid input into the process (kg) by the amount of acrylic acid produced (kg), and the lower the specific unit of lactic acid, the more economical the process is.

[0058]

[0059] The first stage dehydration reactor and the second stage dehydration reactor can be arranged sequentially vertically.

[0060]

[0061] The upper end of the first stage dehydration reactor is connected to a feed supply section where lactic acid gas is supplied. In addition, the dehydration reaction catalyst filled in the first stage dehydration reactor may include at least one selected from the group consisting of a calcium phosphate-based catalyst, a sodium phosphate-based catalyst, and an aluminum phosphate-based catalyst. Other reaction conditions, as long as they are generally used in the technical field to which the present invention pertains, may be used without particular limitation as long as they do not conflict with the contents limited in this specification.

[0062] More specifically, the dehydration catalyst may include CaSO4 / Na2SO4; Na4P2O7 / CaSO4; Na4P2O7 / Ca3(PO4)2; NaH2PO4-NaHCO3 / SiO2; AlPO4-NH3; Ca3(PO4)2 / CaSO4; Ca2P2O7; Ca5(PO4)3(OH), etc.

[0063]

[0064] The lower portion of the first-stage dehydration reactor may include a transfer line connected to the upper portion of the second-stage dehydration reactor. Furthermore, the transfer line may include a heating unit. The lactic acid dehydration reaction is a high-temperature reaction. Therefore, if the temperature of the stream discharged from the first-stage dehydration reactor decreases during the transfer to the second-stage dehydration reactor, heat loss for the dehydration reaction occurs. Therefore, the transfer line may include a heating unit to increase the temperature of the discharged stream to the dehydration reaction temperature.

[0065] For example, the stream discharged from the first stage reactor may have a temperature of about 350 to 360°C, and this stream may be heated to about 390°C by a heating unit while passing through a transfer line and then fed into the second stage reactor.

[0066]

[0067] The upper end of the second-stage dehydration reactor is connected to a transfer line for transferring the stream discharged from the first-stage dehydration reactor. In addition, the dehydration reaction catalyst filled in the second-stage dehydration reactor may include at least one selected from the group consisting of a calcium phosphate-based catalyst, a sodium phosphate-based catalyst, and an aluminum phosphate-based catalyst. Other reaction conditions, as long as they are generally used in the technical field to which the present invention pertains, may be used without special limitations as long as they do not conflict with the contents limited in this specification.

[0068] More specifically, the dehydration catalyst may include CaSO4 / Na2SO4; Na4P2O7 / CaSO4; Na4P2O7 / Ca3(PO4)2; NaH2PO4-NaHCO3 / SiO2; AlPO4-NH3; Ca3(PO4)2 / CaSO4; Ca2P2O7; Ca5(PO4)3(OH), etc.

[0069]

[0070] In the second-stage dehydration reactor, after an additional dehydration reaction is performed, the product stream is discharged from the bottom. Accordingly, a discharge line may be connected to the bottom of the second-stage dehydration reactor.

[0071]

[0072] Additionally, the product stream discharged from the second stage dehydration reactor can be transferred to a condenser along a discharge line. In the condenser, acrylic acid contained in the product stream in a gaseous state can be condensed, liquefied, and captured.

[0073]

[0074] Hereinafter, the method for manufacturing acrylic acid of the present disclosure will be examined step by step.

[0075]

[0076] [Step 1]

[0077] The first step of the present disclosure is a step of supplying a feed stream from a feed supply section to the top of a first-stage dehydration reactor filled with a catalyst, performing a lactic acid dehydration reaction, and then discharging the stream to the bottom.

[0078]

[0079] The feed stream supplied to the top of the first stage dehydration reactor may include vaporized lactic acid gas molecules. For example, the vaporized lactic acid molecules may be obtained by supplying a stream containing lactic acid to a vaporization reactor and causing a vaporization reaction of lactic acid within the vaporization reactor.

[0080]

[0081] The catalyst filled in the first stage dehydration reactor is a catalyst for lactic acid dehydration reaction, and may include at least one selected from the group consisting of a calcium phosphate-based catalyst, a sodium phosphate-based catalyst, and an aluminum phosphate-based catalyst. Other reaction conditions may be used without special limitation as long as they are generally used in the technical field to which the present invention pertains and do not conflict with the contents limited in the present specification.

[0082] More specifically, the dehydration catalyst may include CaSO4 / Na2SO4; Na4P2O7 / CaSO4; Na4P2O7 / Ca3(PO4)2; NaH2PO4-NaHCO3 / SiO2; AlPO4-NH3; Ca3(PO4)2 / CaSO4; Ca2P2O7; Ca5(PO4)3(OH), etc.

[0083]

[0084] The average dehydration reaction temperature of the first stage dehydration reactor may be carried out under a temperature condition of more than 340°C and less than or equal to about 400°C, preferably more than 340°C, or more than 345°C, or more than 350°C, or more than or equal to about 355°C, to less than or equal to about 400°C, or less than or equal to about 390°C, or less than or equal to about 380°C.

[0085] If the dehydration reaction temperature is too low, a problem may arise in which the lactic acid conversion rate and acrylic acid yield are significantly reduced, and conversely, if the dehydration reaction temperature is too high, i) aldehyde production reactions due to decarboxylation or decarbonylation, and ii) propanoic acid production reactions may be further promoted, resulting in a problem in which by-products increase.

[0086]

[0087] A stream that has completed the dehydration reaction can be discharged from the bottom of the first-stage dehydration reactor, and the stream discharged from the bottom of the first-stage dehydration reactor can be transferred to the second-stage dehydration reactor through a transfer line.

[0088] The stream discharged from the bottom of the first stage dehydration reactor may include gaseous acrylic acid produced through the lactic acid dehydration reaction, unreacted lactic acid gas molecules, and byproducts (e.g., acetaldehyde, propionic acid, 2,3-pentanedione, etc.).

[0089]

[0090] The above transfer line is equipped with a heating unit, so that the temperature of the stream discharged from the first stage dehydration reactor can be maintained at 370°C or higher and 410°C or lower while being transferred to the second stage reactor through the transfer line. The heating unit may be a separate heating device, such as a heat exchanger or a heating band.

[0091] The lactic acid dehydration reaction is a high-temperature reaction. Therefore, if the temperature of the stream discharged from the first-stage dehydration reactor decreases during the transfer to the second-stage dehydration reactor, heat loss for the dehydration reaction occurs. Therefore, the transfer line must satisfy the above temperature range to raise the temperature of the discharged stream to the dehydration reaction temperature.

[0092]

[0093] [Stage 2]

[0094] The second step of the present disclosure is a step of supplying a stream discharged from the bottom of the first-stage dehydration reactor to the top of a second-stage dehydration reactor filled with a catalyst, performing a dehydration reaction, and then discharging the stream to the bottom.

[0095]

[0096] The stream discharged from the bottom of the first-stage dehydration reactor and supplied to the top of the second-stage dehydration reactor may contain unreacted lactic acid gas molecules. Additionally, the stream discharged from the bottom of the first-stage dehydration reactor may be supplied to the top of the second-stage dehydration reactor through a transfer line.

[0097]

[0098] The catalyst filled in the second stage dehydration reactor is a catalyst for lactic acid dehydration reaction, and may include at least one selected from the group consisting of a calcium phosphate-based catalyst, a sodium phosphate-based catalyst, and an aluminum phosphate-based catalyst. Other reaction conditions may be used without special limitation as long as they are generally used in the technical field to which the present invention pertains and do not conflict with the contents limited in the present specification.

[0099] More specifically, the dehydration catalyst may include CaSO4 / Na2SO4; Na4P2O7 / CaSO4; Na4P2O7 / Ca3(PO4)2; NaH2PO4-NaHCO3 / SiO2; AlPO4-NH3; Ca3(PO4)2 / CaSO4; Ca2P2O7; Ca5(PO4)3(OH), etc.

[0100]

[0101] The average dehydration reaction temperature of the second stage dehydration reactor may be carried out at a temperature condition of more than 340°C and less than or equal to about 400°C, preferably more than 340°C, or more than or equal to about 345°C, or more than or equal to about 350°C, or more than or equal to about 355°C, to less than or equal to about 400°C, or less than or equal to about 390°C, or less than or equal to about 380°C.

[0102] If the temperature of the dehydration reaction is too low, the problem of a significant decrease in the lactic acid conversion rate and acrylic acid yield may occur, and conversely, if the temperature of the dehydration reaction is too high, i) aldehyde production reactions by decarboxylation or decarbonylation, and ii) propanoic acid production reactions may be further promoted, and the problem of an increase in by-products may occur.

[0103]

[0104] In the second-stage dehydration reactor, after an additional dehydration reaction is performed, the product stream is discharged from the bottom. Accordingly, a discharge line is connected to the bottom of the second-stage dehydration reactor to discharge the product stream.

[0105]

[0106] Additionally, the product stream discharged from the second stage dehydration reactor can be transferred to a condenser along a discharge line. In the condenser, acrylic acid contained in the product stream in a gaseous state can be condensed, liquefied, and captured.

[0107]

[0108] In addition, the method for producing acrylic acid of the present disclosure can satisfy the following mathematical formula 2.

[0109] [Equation 2]

[0110]

[0111] In the above mathematical expression 2, T1 is the average time that the feed stream remains in the first-stage dehydration reactor, and T2 is the average time that the stream supplied to the second-stage dehydration reactor remains in the second-stage dehydration reactor.

[0112] That is, in the case of an acrylic acid production method in which the residence time of the feed stream in the first-stage dehydration reactor is in the range of 0.3 to 0.6 relative to the total reaction time, the yield of acrylic acid obtained from the production method may be 53% or more. In this case, the yield of acrylic acid can be obtained by the following mathematical equation 3.

[0113] [Equation 3]

[0114] Acrylic acid yield (mol%) = (number of moles of acrylic acid produced in the second stage reactor / number of moles of lactic acid introduced into the first stage reactor) * 100

[0115] The number of moles of acrylic acid produced in the second stage reactor is a measurement of the number of moles of acrylic acid in the discharge stream of the second stage reactor, and the number of moles of lactic acid fed to the first stage reactor is a measurement of the number of moles of lactic acid in the feed stream fed to the first stage reactor.

[0116]

[0117] The desired acrylic acid yield of 53 mol% or more is the highest acrylic acid yield in the current process, and since the higher the acrylic acid yield, the lower the specific unit, the higher the acrylic acid yield is better. Specifically, when the acrylic acid yield increases from 50 mol% to 53 mol%, the specific unit of lactic acid decreases by about 5 to 6%. Since the specific unit of lactic acid accounts for the largest proportion of the acrylic acid manufacturing cost, improving the acrylic acid yield is very important for reducing the cost. At this time, the specific unit of lactic acid is the value obtained by dividing the total amount of lactic acid input into the process (kg) by the amount of acrylic acid produced (kg), and the lower the specific unit of lactic acid, the more economical the process is.

[0118]

[0119] In addition, in the case of the dehydration reaction using lactic acid gas, a fixed-bed cylindrical reactor is used, and the length of the catalyst stage of the catalyst packed inside the fixed-bed cylindrical reactor is the same as the reactor length. In addition, the first-stage reactor and the second-stage reactor have the same diameter, but the length of the catalyst stage, i.e., the length of the reactor, are different. That is, the first-stage and second-stage reactors for the dehydration reaction of the present disclosure are each fixed-bed cylindrical reactors, and the residence time of the stream in the first-stage or second-stage reactor is proportional to the length of each catalyst stage, i.e., the reactor.

[0120]

[0121] According to one example of the present invention, an acrylic acid production device is configured with a two-stage reactor, and by controlling the length of the reaction stages, acrylic acid can be obtained at a target yield.

[0122] In addition, according to an example of the present invention, by using a two-stage reactor during the production of acrylic acid and controlling the retention time of the stream in the reactor, acrylic acid can be obtained at a target yield.

[0123]

[0124] Figure 1 is a schematic diagram of an acrylic acid manufacturing device according to one embodiment of the present invention.

[0125] Figure 2 is a graph showing the acrylic acid yield according to formula 1 of one embodiment of the present invention.

[0126]

[0127] Hereinafter, the functions and effects of the invention will be described in more detail through specific examples. However, these examples are provided merely as examples of the invention and do not define the scope of the invention.

[0128]

[0129] [Preparation of lactic acid feed stream in the atmosphere]

[0130] As a lactic acid raw material, an aqueous lactic acid solution having a concentration of 88 wt% (trade name: PURAC H888, obtained from Corbion) was prepared. The lactic acid raw material and distilled water were mixed in a weight ratio of 1:1.2 and refluxed at a temperature of about 95°C for about 18 hours to obtain an aqueous lactic acid solution having a concentration of about 40 wt% in which lactic acid and lactic acid oligomers reached an equilibrium state, which was used as a feed for lactic acid vaporization. Nitrogen was used as a carrier gas, and the temperature inside the vaporization reactor was set to be 200°C to 300°C. The lactic acid molecule feed vaporized in the vaporization reactor was used as a feed for the dehydration reaction.

[0131]

[0132] Experimental Example 1

[0133] [Example 1]

[0134] The two-stage dehydration reactors for the dehydration reaction were each fixed-bed reactors filled with a dehydration reaction catalyst. The first-stage dehydration reactor had a length of 1.5 m and an inner diameter of 4 m. The length and inner diameter of the second-stage dehydration reactor were configured to be the same as those of the first-stage dehydration reactor. Therefore, the value of mathematical equation 1 became 0.5. The first-stage and second-stage dehydration reactors used Hastelloy material. In addition, the first-stage dehydration reactor and the second-stage dehydration reactor were each filled with a dehydration reaction catalyst.

[0135] A feed stream supply section was provided at the top of the first-stage dehydration reactor, through which vaporized lactic acid molecule feed was supplied. A transfer line was provided between the first-stage and second-stage dehydration reactors, and a temperature controller was used to maintain the temperature at 390°C. A shell-and-tube type heat exchanger was used as the temperature controller. In addition, a discharge line was provided at the bottom of the second-stage dehydration reactor, through which the reaction product after the dehydration reaction was discharged.

[0136] As a dehydration reaction catalyst, a composite calcium phosphate catalyst composed of Ca2P2O7 and Ca5(PO4)3(OH) formed into cylindrical pellets with a diameter of approximately 3 mm and a length of approximately 3 mm was used. At this time, the mixing weight ratio of Ca2P2O7 and Ca5(PO4)3(OH) was 7:3.

[0137]

[0138] A vaporized lactic acid feed stream having a temperature of 390°C was supplied to the top of the first-stage dehydration reactor. The residence time of the vaporized lactic acid feed stream inside the first-stage dehydration reactor was 0.8 seconds. At this time, the temperature drop in the first-stage dehydration reactor was 38.4°C, and the discharge temperature from the first-stage dehydration reactor was 351.6°C.

[0139] The stream that completed the reaction in the first-stage dehydration reactor was transferred to the second-stage dehydration reactor via a transfer line. At this time, the temperature of the stream directly discharged from the first-stage dehydration reactor was 351.6°C. Accordingly, the stream discharged from the first-stage dehydration reactor was heated in a transfer line connected to the bottom of the first-stage dehydration reactor so that the temperature became 390°C when introduced into the second-stage dehydration reactor.

[0140] At this time, the residence time of the stream transferred from the first-stage dehydration reactor inside the second-stage dehydration reactor was 0.75 seconds. Accordingly, the value of mathematical expression 2 was 0.51.

[0141] The product stream that completed the dehydration reaction in the second stage dehydration reactor was discharged through the discharge line, and its temperature was 368.8℃.

[0142]

[0143] The product stream discharged from the second-stage dehydration reactor was collected and quantitatively analyzed using high-performance liquid chromatography (HPLC) to calculate the yield of acrylic acid and the conversion rate of lactic acid.

[0144]

[0145] High-performance liquid chromatography was analyzed using the following method.

[0146] The obtained reaction product was diluted 20 times by volume using distilled water, and then quantitatively analyzed using HPLC using Agilent 1260 Infinity II. The HPLC analysis conditions are as follows.

[0147] -Eluent: 0.005 mol H2SO4(aq)

[0148] -Eluent flow rate: 0.4 mL / min

[0149] -Column: Aminex HPX-87H

[0150] -Column temperature: 10℃

[0151] -Detector: UV 210~300 nm

[0152] -Analysis time: 70 min

[0153] -Analysis pressure: ~70 bar

[0154]

[0155] The acrylic acid yield was calculated according to the following mathematical formula 3.

[0156] [Equation 3]

[0157] Acrylic acid yield (mol%) = (number of moles of acrylic acid produced in the second stage reactor / number of moles of lactic acid introduced into the first stage reactor) * 100

[0158] The number of moles of acrylic acid produced in the second stage reactor is a measurement of the number of moles of acrylic acid in the discharge stream of the second stage reactor, and the number of moles of lactic acid fed to the first stage reactor is a measurement of the number of moles of lactic acid in the feed stream fed to the first stage reactor.

[0159]

[0160] The lactic acid conversion rate was calculated according to the following mathematical formula 4.

[0161] [Equation 4]

[0162] Lactic acid conversion rate (%) = {lactic acid input (kg / hr) - lactic acid flowrate at the second stage reactor outlet (kg / hr)} / lactic acid input (kg / hr) * 100

[0163]

[0164] [Example 2]

[0165] The two-stage dehydration reactors for the dehydration reaction were each fixed-bed reactors filled with a dehydration reaction catalyst. The first-stage dehydration reactor had a length of 1 m and an inner diameter of 4 m. The second-stage dehydration reactor had a length of 2 m and an inner diameter of 4 m. Therefore, the value of mathematical equation 1 became approximately 0.33. Hastelloy was used as the material for the first-stage and second-stage dehydration reactors. In addition, a dehydration reaction catalyst was filled in each of the first-stage and second-stage dehydration reactors.

[0166] A feed stream supply section was provided at the top of the first-stage dehydration reactor, through which vaporized lactic acid molecule feed was supplied. A transfer line was provided between the first-stage and second-stage dehydration reactors, and a temperature controller was used to maintain the temperature at 390°C. A shell-and-tube type heat exchanger was used as the temperature controller. In addition, a discharge line was provided at the bottom of the second-stage dehydration reactor, through which the reaction product after the dehydration reaction was discharged.

[0167] As a dehydration reaction catalyst, a composite calcium phosphate catalyst composed of Ca2P2O7 and Ca5(PO4)3(OH) formed into cylindrical pellets with a diameter of approximately 3 mm and a length of approximately 3 mm was used. At this time, the mixing weight ratio of Ca2P2O7 and Ca5(PO4)3(OH) was 7:3.

[0168]

[0169] A vaporized lactic acid feed stream having a temperature of 390°C was supplied to the top of the first-stage dehydration reactor. The residence time of the vaporized lactic acid feed stream inside the first-stage dehydration reactor was 0.5 seconds. At this time, the temperature drop in the first-stage dehydration reactor was approximately 33°C, and the discharge temperature from the first-stage dehydration reactor was 357°C.

[0170] The stream that completed the reaction in the first-stage dehydration reactor was transferred to the second-stage dehydration reactor via a transfer line. At this time, the temperature of the stream directly discharged from the first-stage dehydration reactor was 357°C. Accordingly, the stream discharged from the first-stage dehydration reactor was heated in a transfer line connected to the bottom of the first-stage dehydration reactor so that the temperature became 390°C when introduced into the second-stage dehydration reactor.

[0171] At this time, the residence time of the stream transferred from the first-stage dehydration reactor inside the second-stage dehydration reactor was 1 second. Accordingly, the value of mathematical expression 2 was 0.33.

[0172] The product stream that completed the dehydration reaction in the second stage dehydration reactor was discharged through the discharge line, and its temperature was 363 ℃.

[0173]

[0174] The product stream discharged from the second stage dehydration reactor was collected and quantitatively analyzed using high performance liquid chromatography (HPLC), and the yield of acrylic acid and the conversion rate of lactic acid were calculated as in Example 1.

[0175]

[0176] [Example 3]

[0177] The two-stage dehydration reactors for the dehydration reaction were each fixed-bed reactors filled with a dehydration reaction catalyst. The first-stage dehydration reactor had a length of 1.7 m and an inner diameter of 4 m. The second-stage dehydration reactor had a length of 1.3 m and an inner diameter of 4 m. Therefore, the value of mathematical equation 1 became 0.57. Hastelloy was used as the material for the first-stage and second-stage dehydration reactors. In addition, a dehydration reaction catalyst was filled in each of the first-stage and second-stage dehydration reactors.

[0178] A feed stream supply section was provided at the top of the first-stage dehydration reactor through which vaporized lactic acid molecule feed was supplied. A transfer line was provided between the first-stage and second-stage dehydration reactors, and a temperature controller was used to maintain the temperature at 390°C. A shell-and-tube type heat exchanger was used as the temperature controller. In addition, a discharge line was provided at the bottom of the second-stage dehydration reactor to discharge the reaction product after completing the dehydration reaction.

[0179] As a dehydration reaction catalyst, a composite calcium phosphate catalyst composed of Ca2P2O7 and Ca5(PO4)3(OH) formed into cylindrical pellets with a diameter of approximately 3 mm and a length of approximately 3 mm was used. At this time, the mixing weight ratio of Ca2P2O7 and Ca5(PO4)3(OH) was 7:3.

[0180]

[0181] A vaporized lactic acid feed stream having a temperature of 390°C was supplied to the top of the first-stage dehydration reactor. The residence time of the vaporized lactic acid feed stream inside the first-stage dehydration reactor was 0.9 seconds. At this time, the temperature drop in the first-stage dehydration reactor was approximately 40°C, and the discharge temperature from the first-stage dehydration reactor was 350°C.

[0182] The stream that completed the reaction in the first-stage dehydration reactor was transferred to the second-stage dehydration reactor via a transfer line. At this time, the temperature of the stream directly discharged from the first-stage dehydration reactor was 350°C. Accordingly, the stream discharged from the first-stage dehydration reactor was heated in a transfer line connected to the bottom of the first-stage dehydration reactor so that the temperature became 390°C when introduced into the second-stage dehydration reactor.

[0183] At this time, the residence time of the stream transferred from the first-stage dehydration reactor inside the second-stage dehydration reactor was 0.64 seconds. Accordingly, the value of mathematical expression 2 was 0.58.

[0184] The product stream that completed the dehydration reaction in the second stage dehydration reactor was discharged through the discharge line, and its temperature was 371℃.

[0185]

[0186] The product stream discharged from the second stage dehydration reactor was collected and quantitatively analyzed using high performance liquid chromatography (HPLC), and the yield of acrylic acid and the conversion rate of lactic acid were calculated as in Example 1.

[0187]

[0188] [Comparative Example 1]

[0189] The two-stage dehydration reactors for the dehydration reaction are each fixed-bed reactors filled with a dehydration reaction catalyst. The first-stage dehydration reactor had a length of 0.2 m and an inner diameter of 4 m. The second-stage dehydration reactor had a length of 2.8 m and an inner diameter of 4 m. Therefore, the value of mathematical equation 1 became 0.07. The first-stage and second-stage dehydration reactors used Hastelloy material. In addition, the first-stage and second-stage dehydration reactors were each filled with a dehydration reaction catalyst.

[0190] A feed stream supply section was provided at the top of the first-stage dehydration reactor, through which vaporized lactic acid molecule feed was supplied. A transfer line was provided between the first-stage and second-stage dehydration reactors, and a temperature controller was used to maintain the temperature at 390°C. A shell-and-tube type heat exchanger was used as the temperature controller. In addition, a discharge line was provided at the bottom of the second-stage dehydration reactor, through which the reaction product after the dehydration reaction was discharged.

[0191] As a dehydration reaction catalyst, a composite calcium phosphate catalyst composed of Ca2P2O7 and Ca5(PO4)3(OH) formed into cylindrical pellets with a diameter of approximately 3 mm and a length of approximately 3 mm was used. At this time, the mixing weight ratio of Ca2P2O7 and Ca5(PO4)3(OH) was 7:3.

[0192]

[0193] A vaporized lactic acid feed stream having a temperature of 390°C was supplied to the top of the first-stage dehydration reactor. The residence time of the vaporized lactic acid feed stream inside the first-stage dehydration reactor was 0.1 second. At this time, the temperature drop in the first-stage dehydration reactor was approximately 13.6°C, and the discharge temperature from the first-stage dehydration reactor was 376.4°C.

[0194] The stream that completed the reaction in the first-stage dehydration reactor was transferred to the second-stage dehydration reactor via a transfer line. At this time, the temperature of the stream directly discharged from the first-stage dehydration reactor was 376.4°C. Accordingly, the stream discharged from the first-stage dehydration reactor was heated in a transfer line connected to the bottom of the first-stage dehydration reactor so that the temperature became 390°C when introduced into the second-stage dehydration reactor.

[0195] At this time, the residence time inside the second-stage dehydration reactor of the stream transferred from the first-stage dehydration reactor was 1.4 seconds. Accordingly, the value of mathematical expression 2 was 0.07.

[0196] The product stream that completed the dehydration reaction in the second stage dehydration reactor was discharged through the discharge line, and its temperature was 349.4℃.

[0197]

[0198] Likewise, the product stream after the reaction was completed was collected from the bottom of the second-stage dehydration reactor and quantitatively analyzed by HPLC to calculate the yield of acrylic acid and the conversion rate of lactic acid. The HPLC analysis method and the method for calculating the yield of acrylic acid and the conversion rate of lactic acid were performed in the same manner as in Example 1.

[0199]

[0200] [Comparative Example 2]

[0201] The two-stage dehydration reactors for the dehydration reaction are each fixed-bed reactors filled with a dehydration reaction catalyst. The first-stage dehydration reactor had a length of 2.5 m and an inner diameter of 4 m. The second-stage dehydration reactor had a length of 0.5 m and an inner diameter of 4 m. Therefore, the value of mathematical equation 1 became 0.83. The first-stage and second-stage dehydration reactors used Hastelloy material. In addition, the first-stage and second-stage dehydration reactors were each filled with a dehydration reaction catalyst.

[0202] A feed stream supply section was provided at the top of the first-stage dehydration reactor, through which vaporized lactic acid molecule feed was supplied. A transfer line was provided between the first-stage and second-stage dehydration reactors, and a temperature controller was used to maintain the temperature at 390°C. A shell-and-tube type heat exchanger was used as the temperature controller. In addition, a discharge line was provided at the bottom of the second-stage dehydration reactor, through which the reaction product after the dehydration reaction was discharged.

[0203] As a dehydration reaction catalyst, a composite calcium phosphate catalyst composed of Ca2P2O7 and Ca5(PO4)3(OH) formed into cylindrical pellets with a diameter of approximately 3 mm and a length of approximately 3 mm was used. At this time, the mixing weight ratio of Ca2P2O7 and Ca5(PO4)3(OH) was 7:3.

[0204]

[0205] A vaporized lactic acid feed stream having a temperature of 390°C was supplied to the top of the first-stage dehydration reactor. The residence time of the vaporized lactic acid feed stream inside the first-stage dehydration reactor was 1.3 seconds. At this time, the temperature drop in the first-stage dehydration reactor was approximately 44.3°C, and the discharge temperature from the first-stage dehydration reactor was 345.7°C.

[0206] The stream that completed the reaction in the first-stage dehydration reactor was transferred to the second-stage dehydration reactor via a transfer line. At this time, the temperature of the stream directly discharged from the first-stage dehydration reactor was 345.7°C. Accordingly, the stream discharged from the first-stage dehydration reactor was heated in a transfer line connected to the bottom of the first-stage dehydration reactor so that the temperature became 390°C when introduced into the second-stage dehydration reactor.

[0207] At this time, the residence time inside the second-stage dehydration reactor of the stream transferred from the first-stage dehydration reactor was 0.24 seconds. Accordingly, the value of mathematical expression 2 was 0.84.

[0208] The product stream that completed the dehydration reaction in the second stage dehydration reactor was discharged through the discharge line, and its temperature was 380.5℃.

[0209]

[0210] Likewise, the product stream after the reaction was completed was collected from the bottom of the second-stage dehydration reactor and quantitatively analyzed by HPLC to calculate the yield of acrylic acid and the conversion rate of lactic acid. The HPLC analysis method and the method for calculating the yield of acrylic acid and the conversion rate of lactic acid were performed in the same manner as in Example 1.

[0211]

[0212] The reaction conditions of Example 1 and Comparative Examples 1 and 2 and the yield of acrylic acid and lactic acid conversion rate obtained from the reaction are shown in Table 1 below.

[0213]

[0214] Comparative Example 1 Example 1 Example 2 Example 3 Comparative Example 2 Mathematical Formula 1 (L1 / (L1+L2)) 0.07 0.5 0.3 3 0.5 7 0.8 1st stage reactor input temperature (℃) 390 390 390 390 390 1st stage reactor dT (℃) 13.6 38.4 38.4 39.9 4 4.3 1st stage reactor discharge temperature (℃) 376.4 35 1.6 35 6.5 35 0.1 34 5.7 2nd stage reactor input temperature (℃) 390 390 390 390 390 2nd stage reactor dT (℃) 40.6 2 1.2 2 6.8 19.19.5 2nd stage reactor discharge Temperature (℃) 349.4 368.8 363.2 370.9 380.5 Acrylic acid yield (mol%) 48.6 53.4 53.5 53.0 49.1 Lactic acid conversion (mol%) 76.6 83.9 84.6 83.1 76.4

[0215] As a result of the experiment, it was confirmed that in the case of examples satisfying mathematical formula 1 of the present disclosure, the target yield of 53% or more was achieved, but in the case of comparative examples that did not satisfy this, the yield was less than 53%.

[0216]

[0217] Experimental Example 2

[0218] Using the simulation program Aspen Plus V11 and gPROCESS 2022.1.0, the yield of acrylic acid (mol%) according to the value of mathematical expression 1 was simulated by using the value of mathematical expression 1 (L1 / (L1+L2)) as a variable, and the results are shown in Table 2 and Figure 2 below.

[0219] The dehydration reaction conditions of the simulation program were entered as a two-stage reactor with reference to Experimental Example 1.

[0220] The value of mathematical formula 1 (L1 / (L1+L2)) 0.930.830.670.500.330.170.07 Acrylic acid yield (mol%) 45.849.152.153.453.552.148.6

[0221] Referring to Table 2 and Figure 2, it was confirmed that the resulting acrylic acid yield was expressed in the form of a quadratic function with a negative coefficient of the highest term, and it was confirmed that in order to exhibit an acrylic acid yield of 53 mol% or more, which is the target yield of the present invention, the value of L must satisfy 0.3 to 0.6.

Claims

1. In a two-stage reactor for lactic acid dehydration reaction, Feed supply section where lactic acid gas is supplied; A first stage dehydration reactor filled with a catalyst for lactic acid dehydration reaction; and A second stage dehydration reactor filled with a catalyst for lactic acid dehydration reaction; An acrylic acid manufacturing device satisfying the following mathematical formula 1: [Mathematical formula 1] In the above mathematical expression 1, L 1 is the length of the first stage dehydration reactor, and L 2 is the length of the second stage dehydration reactor.

2. In paragraph 1, The yield of acrylic acid obtained from the above acrylic acid manufacturing device is 53% or more. Acrylic acid manufacturing equipment.

3. In paragraph 1, The first stage dehydration reactor and the second stage dehydration reactor are connected by a transfer line, and the transfer line further includes a heating unit. Apparatus for manufacturing acrylic acid.

4. A first stage of supplying a feed stream containing lactic acid gas molecules to the top of a first-stage dehydration reactor filled with a catalyst from a feed supply section, performing a dehydration reaction, and then discharging the stream to the bottom; A second stage is provided, which supplies the stream discharged from the bottom of the first stage dehydration reactor to the top of the second stage dehydration reactor filled with a catalyst, and discharges the stream to the bottom after the dehydration reaction is performed; The feed stream supplied to the top of the first stage dehydration reactor contains lactic acid gas, Satisfying the following mathematical expression 2, Method for producing acrylic acid: [Mathematical formula 2] In the above mathematical expression 2, T 1 is the average residence time of the feed stream in the first stage dehydration reactor, and T 2 is the average time that the stream supplied to the second-stage dehydration reactor remains in the second-stage dehydration reactor.

5. In paragraph 4, The above method for producing acrylic acid has an acrylic acid yield of 53 mol% or more. Method for producing acrylic acid.

6. In paragraph 4, The stream discharged from the bottom of the first stage dehydration reactor is transferred to the second stage dehydration reactor through a transfer line, and the temperature of the stream is maintained at 370°C or higher and 410°C or lower during transfer. Method for producing acrylic acid.

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