Shell-and-tube reactor used for the synthesis of polycarbonate polyether polyols.

Abstract

A shell-and-tube reactor for synthesizing polycarbonate polyether polyols is provided. [Solution] The shell-and-tube reactor achieves a high degree of compatibility and overall cooperation between the reactor's internal structure and material circulation and reaction heat control by combining a solid-liquid mixing unit, a carbon dioxide epoxy compound mixing heat transfer unit, a circulation control unit, a temperature control unit, and a pressure control unit in a specific configuration. This provides sufficient mixing, material transfer / heat transfer, and precise temperature control conditions in the synthesis of polycarbonate polyether polyols, enabling the production of polycarbonate polyether polyols by a single, concentrated injection. The shell-and-tube reactor of the present invention can improve the stability and production efficiency of the reaction process, making it advantageous for large-scale industrial production of polycarbonate polyether polyols.

Description

[Technical Field]

[0001] The present invention relates to the technology for the production of polycarbonate polyether polyols, and more particularly to a shell-and-tube reactor used in the synthesis of polycarbonate polyether polyols. [Background technology]

[0002] Polycarbonate polyether polyols are a type of polyhydric alcohol that has a carbonate group in its molecule and a hydroxyl group at the end of its molecular chain.

[0003] One of its raw materials, carbon dioxide, is inexpensive, readily available, non-toxic, non-flammable, and possesses a clear chemical fixation effect.

[0004] Furthermore, this reaction does not require high temperatures and consumes little energy.

[0005] The controlled copolymerization method of carbon dioxide and epoxy compounds has a wide range of applications and high industrial value.

[0006] The synthesis process for polycarbonate polyether polyols is primarily carried out by copolymerizing a chain transfer agent, carbon dioxide, and an epoxy compound using a zinc-cobalt dimetal catalyst.

[0007] For example, when epoxypropane and succinic acid are used as chain transfer agents, the synthesis route is as shown in the following equation. JPEG2026085883000002.jpg35163

[0008] Here, m1 and m2 represent the average number of ether chain segments, and n1 and n2 represent the average number of ester chain segments. Chinese patent CN111378106A states that the activation energy of the resulting polymer is lower than that of the cyclic carbonate, and the potential energy of the cyclic carbonate is lower than that of the polymer. Therefore, the reaction of cyclic carbonate formation is thermodynamically favorable, and the reaction of polycarbonate formation is kinetically favorable.

[0009] Therefore, if the reaction temperature is too high, the content of carbonate chain segments decreases, the molecular weight distribution broadens, and the proportion of cyclic carbonates, which are by-products, increases. For this reason, precise control of the reaction temperature is key to increasing the efficiency of the production of the main product, polycarbonate polyether polyol.

[0010] Another important factor affecting the yield of the main product is the action of the dimetallic complex (DMC) catalyst. If activation is insufficient or instantaneous, "explosive polymerization" is likely to occur, potentially leading to safety accidents due to high temperature and pressure. Chinese patent CN115785435A classifies the reaction mechanism of the DMC catalyst into an "inducible activation phase" and a "chain segment growth phase."

[0011] During the induction activation phase, the reaction is exothermic, so it is important to pay attention to the temperature peak and control the initial activation temperature to avoid overheating, which is crucial to preventing damage to the pressure resistance and catalytic activity of the apparatus. In the chain segment growth phase, after the DMC is fully activated, the active site binds to the chain transfer agent, and the epoxy compound is inserted, allowing polymerization to proceed. At this time, the chain transfer agent undergoes a substitution reaction with the active structures of the DMC and epoxy compound, and external heat supply is necessary to promote chain growth at this stage.

[0012] Furthermore, Chinese patent CN106471042B defines the activation procedure for the DMC catalyst during the induction activation phase, which involves adding a portion of the epoxy alkane to the DMC catalyst in the presence of CO2, and then temporarily stopping the addition of the epoxy compound. At this time, a temperature peak (a so-called "hot spot") and a pressure drop are observed in the reactor due to the subsequent exothermic chemical reaction. The activation time interval refers to the time interval from the addition of a portion of the epoxy compound to the DMC catalyst in the presence of CO2 until the hot spot subsides.

[0013] In order to adapt to the characteristics of the polycarbonate polyether polyol synthesis reaction described above and to reduce the influence of heat fluctuations on each component during the reaction, conventional techniques all require special catalyst design, process control, and / or independent reactor design in the induction activation step.

[0014] The specific conventional technologies are as follows: (1) Conventional technology uses a special high-performance DMC catalyst.

[0015] For example, as described in Chinese patent CN115785435B, by using a highly active and heat-resistant tridentate dimetallic complex catalyst (DMC), it is possible to produce polyether polyols by simultaneously adding the tridentate dimetallic complex catalyst DMC, a chain transfer agent, and an epoxy compound at room temperature.

[0016] (2) From the perspective of process improvement, the catalyst pre-activation technique is employed in Chinese patent CN116710504A.

[0017] In other words, this method involves preactivating the catalyst using the starting compound or the products of the first, second, or third reaction. First, the catalyst is activated using a portion of the raw materials to initiate the reaction, and then the remaining raw materials are added in stages or continuously.

[0018] Furthermore, Chinese patent CN107108878A proposes a method for producing polyether carbonate polyols, stating that the DMC catalyst "needs to be pre-treated at a temperature of 50-200°C and / or under reduced pressure conditions of 10-800 mbar (absolute pressure)." It also states that in this method, "a dimetallic cyanide catalyst, oxyethylene, a suspension agent, and / or an H-functionalized compound are added to the first reactor at least intermittently in a continuous metering manner," indicating that the process requires catalyst pre-activation and phased addition of reactants.

[0019] (3) Regarding improvements to the reactor, Chinese Patent CN116874759A proposes a method for activating and maintaining the activity of the catalyst using an independent reactor.

[0020] This technology addresses problems such as insufficient activation of the DMC catalyst, the tendency for explosive polymerization to occur due to instantaneous activation, and the resulting high safety risks. It consists of a first reactor, a tubular reactor, and a second reactor.

[0021] The first reactor is used to activate the DMC catalyst. Specifically, the chain transfer agent and the DMC catalyst are placed in the first reactor, the temperature is raised to 120-140°C, and then the epoxy compound is added to activate the catalyst.

[0022] After activation, an epoxy compound is added to maintain catalytic activity and reduce the temperature to 70-90°C.

[0023] Furthermore, Chinese patent CN103403060B describes how the DMC-induced activation phase can be controlled by connecting two tubular reactors with different inner diameters in series and introducing an independent reactor.

[0024] Furthermore, Chinese patent CN106471042B employs a method in which a stirred tank type main reactor and a tubular reactor are connected in series, and the temperature of the tubular reactor is controlled to be 10 to 40°C higher than the temperature of the main reactor, thereby allowing the induction activation phase of DMC to proceed in the main reactor and the chain segment growth phase to proceed in the tubular reactor.

[0025] However, from the perspective of optimizing the reactor structure, no technology regarding the reactor structure for manufacturing polycarbonate polyether polyol by single - time concentrated feeding has been reported so far.

[0026] Currently, the reactors used in the industrial production of polycarbonate polyether polyol are classified into kettle - type reactors and tubular reactors according to their forms.

[0027] Kettle - type reactors have a low surface - area - to - volume ratio and poor heat - dissipation performance, so it is difficult to control high - exothermic reactions.

[0028] On the other hand, tubular reactors are easy to control the pressure and temperature during the reaction process, and have high monomer conversion efficiency, so they have attracted attention in this field.

[0029] However, since tubular reactors have a small cross - sectional area and limited production capacity, it is necessary to arrange multiple tubular reactors in an array as a shell - and - tube type reactor. However, in a self - circulating type tube - in - tube reactor equipped with a high - efficiency mixer as described in Chinese Patent CN109225114A, the inside of the shell - and - tube type reactor is composed of multiple tubes, and the structure is such that materials are mixed by an external mixer.

[0030] However, in the synthesis process of polycarbonate polyether polyol, the requirements for material mixing and heat dissipation are even higher. It is necessary to immediately release the heat generated during the reaction, disperse the materials at the same time, and prevent explosive polymerization. Furthermore, solid catalysts are likely to accumulate on the upper end closures of multiple tubes in the tube - in - tube reactor, which hinders the progress of the reaction. Therefore, general - purpose tube - in - tube reactors are not suitable for the industrial production of polycarbonate polyether polyol.

Prior Art Documents

Patent Documents

[0031]

Patent Document 1

[0032] To overcome the shortcomings of conventional technology, the present invention provides a shell-and-tube reactor specifically designed for the synthesis of polycarbonate polyether polyols.

[0033] This invention employs reaction tubes with a small aspect ratio and arranges specific carbon dioxide epoxy compound mixing heat transfer units, solid-liquid mixing units, circulation control units, temperature control units, and pressure control units to achieve a high degree of integration and overall cooperation between the internal structure of a shell-and-tube reactor and material circulation and reaction heat control.

[0034] Therefore, the present invention is particularly suitable for large-scale industrial production of polycarbonate polyether polyols. [Means for solving the problem]

[0035] The technical means of the present invention are as follows: That is, a shell-and-tube reactor used for the synthesis of polycarbonate polyether polyols, comprising a reaction pipeline, and further including the following components:

[0036] A carbon dioxide epoxy compound mixed heat transfer unit (used to lower the material temperature) is located at the top of the reaction pipeline. A solid-liquid mixing unit is located below the heat transfer unit, inside the reaction tube. Circulation control unit for circulating and flowing materials within a reaction tube. Temperature control unit that controls the temperature inside the reaction tube Pressure control unit that controls the pressure inside the reaction tube The circulation control unit, temperature control unit, and pressure control unit work together to control the progress of the entire reaction.

[0037] The specific steps are as follows: After the epoxy compound, chain transfer agent, and catalyst are added to the reaction tube all at once, only carbon dioxide is replenished during the reaction process.

[0038] The circulation control unit transports the material from the solid-liquid mixing unit to the carbon dioxide epoxy compound mixing heat transfer unit, and returns it to the solid-liquid mixing unit after the material temperature has decreased.

[0039] The circulation control unit adjusts the circulation speed of the material, and simultaneously adjusts the temperature control unit and pressure control unit. The temperature of the material in the upper part of the reaction tube is kept lower than that in the lower part, and the temperature difference between the material in the middle and lower parts of the reaction tube is controlled to be within 5°C.

[0040] The temperature of the materials inside the reaction tube is maintained to change gradually along the flow direction.

[0041] The ratio of the length to the diameter (L:d) of the reaction tube is less than 50.

[0042] The aforementioned material is a mixture of reaction raw materials and reaction products, and includes, but is not limited to, epoxy compounds, chain transfer agents, catalysts, and polycarbonate polyether polyols.

[0043] The reaction proceeds in a reaction tube, during which epoxy compounds and chain transfer agents are consumed. The reaction continues continuously under the action of the DMC catalyst, producing a polycarbonate polyether polyol, and increasing the viscosity and density of the overall material.

[0044] The carbon dioxide epoxy compound mixed heat transfer unit includes a gas-liquid transfer and heat transfer region, in which the epoxy compound absorbs carbon dioxide, and the carbon dioxide absorbs heat from the liquid, thereby achieving mass and heat transfer between gas and liquid and lowering the material temperature.

[0045] The aforementioned "single-component input" means that the epoxy compound, chain transfer agent, and catalyst are added to a shell-and-tube reactor at the same time to carry out the reaction, with only carbon dioxide being replenished during the reaction process, and no additional input of these three raw materials.

[0046] The shell-and-tube reactor of the present invention can provide sufficient mixing, mass and heat transfer, and precise temperature control conditions in the synthesis of polycarbonate polyether polyols.

[0047] There is no need to use a catalyst with a special structure, and pre-activation of the catalyst is also unnecessary.

[0048] The catalyst induction activation phase and chain segment growth phase can proceed within the same reaction tube, enabling a process for producing polycarbonate polyether polyols through a single, concentrated injection.

[0049] This allows for the synthesis of high-quality polycarbonate polyether polyols without causing scale-up effects (expansion effects), making them suitable for large-scale industrial production.

[0050] The present invention employs a reaction tube with a major-to-minus ratio L:d < 50, comprising a specific carbon dioxide epoxy compound mixing heat transfer unit, a solid-liquid mixing unit, a circulation control unit, a temperature control unit, and a pressure control unit. These units and the entire reaction tube work together to achieve mixing of materials and heat / protein transfer, enabling precise temperature control at specific locations within the reaction tube, thereby facilitating efficient heat dissipation of materials and preventing explosive polymerization.

[0051] In one embodiment, the temperature control unit includes a temperature sensor that indicates the material temperature in three different regions of the reaction tube: upper, middle, and lower; a jacket for heating or cooling the reaction tube; and a heat transfer medium filled between the jacket and the reaction tube.

[0052] In one embodiment, if the temperature in the middle of the reaction tube exceeds the reaction temperature threshold, the temperature control unit is adjusted to lower the temperature inside the reaction tube, and the material circulation rate and carbon dioxide gas replenishment rate are increased until the temperature in the middle of the reaction tube is maintained within the reaction temperature threshold range.

[0053] Furthermore, if the temperature difference between the middle and lower parts of the reaction tube exceeds the temperature difference threshold, the material circulation rate and the carbon dioxide gas replenishment rate are increased to control the temperature difference so that it does not exceed the threshold.

[0054] In one embodiment, a density sensor indicating the density of the material is provided at the outlet of the reaction tube, and the reaction proceeds are controlled based on the rate of change in the material density.

[0055] In one embodiment, the process for controlling the progress of the overall reaction further includes increasing the material circulation rate and the carbon dioxide gas replenishment rate if the change in the density of the material per minute exceeds a threshold for the rate of density change, so that the rate of density change does not exceed the threshold.

[0056] In one embodiment, the carbon dioxide epoxy compound mixed heat transfer unit is located in the gas-liquid heat transfer region, which is the upper space of the reaction tube, and its volume is 20% or more of the total volume of the reaction tube.

[0057] In one embodiment, the carbon dioxide epoxy compound mixed heat transfer unit includes a gas distributor, which is located 10 to 50 mm from the top of the reaction tube and has a porous structure.

[0058] Preferably, the pores are elliptical, with a major axis of 2 mm and a minor axis of 1 mm.

[0059] Preferably, the porous structure has a rectangular arrangement, and the distance between holes is 3 mm.

[0060] In one embodiment, the solid-liquid mixing unit includes a mixer, preferably a static mixer.

[0061] In one embodiment, the inner diameter of the reaction tube is 100 to 1500 mm.

[0062] In one embodiment, the ratio of the major axis to the major axis of the reaction tube satisfies 10 ≤ L:d ≤ 40.

[0063] In one embodiment, the number of reaction tubes is 2 to 8.

[0064] In one embodiment, the reaction tubes are connected in parallel, and the distance between the centers of adjacent tubes is less than or equal to twice the tube diameter.

[0065] In one embodiment, each reaction tube is independent of the others and is closed and isolated by a valve.

[0066] In one embodiment, the material circulation path formed between each reaction tube and the circulation unit is identical.

[0067] In one embodiment, the circulation speed of the circulation unit is 10-20 minutes / circulation. [Effects of the Invention]

[0068] Compared to conventional technologies, the shell-and-tube reactor of the present invention employs a reaction tube with a small major-to-minus ratio and incorporates a specific carbon dioxide epoxy compound mixing heat transfer unit, solid-liquid mixing unit, circulation control unit, temperature control unit, and pressure control unit. These units work together with the entire reaction tube to provide sufficient mixing, mass and heat transfer, and precise temperature control conditions for the synthesis of polycarbonate polyether polyols, resulting in the following advantageous effects.

[0069] (1) By coordinating the reaction process based on the temperature, pressure, and material density inside the reaction tube, and utilizing the circulating flow of materials, highly efficient mixing, effective heat transfer, and precise temperature control can be achieved, enabling the synthesis of high-quality polycarbonate polyether polyols.

[0070] (2) By using only conventional catalysts and eliminating the need for catalyst pre-activation, the catalyst induction activation phase and chain segment growth phase can proceed in the same reaction tube, enabling a polycarbonate polyether polyol production process with a single, concentrated injection.

[0071] (3) It does not have a scale-up effect (amplification effect), which is advantageous for large-scale industrial production of polycarbonate polyether polyols. [Brief explanation of the drawing]

[0072] To more clearly illustrate embodiments of the present invention or technical means relating to the prior art, the drawings used in the embodiments are briefly introduced below. As will be apparent, the drawings described below represent only a few embodiments of the present invention, and those skilled in the art can obtain other drawings based on these without any creative effort.

[0073] [Figure 1] This is a schematic side view of a shell-and-tube reactor according to an embodiment of the present invention. [Figure 2] This is a schematic diagram of the top (overhead view) of a shell-and-tube type reactor according to an embodiment of the present invention. [Figure 3]This is a comparative diagram of the density change curves of polycarbonate polyether polyol in Example 1 and Comparative Examples 1-7. [Modes for carrying out the invention]

[0074] To further clarify the object, technical means, and advantages of the present invention, embodiments of the present invention will be described in more detail below with reference to the drawings. Needless to say, the embodiments described herein represent only a portion of the present invention and do not constitute all embodiments of the present invention. It should be understood that the present invention is not limited to the exemplary embodiments described herein. Furthermore, in the description of the present invention, terms indicating direction or positional relationships such as "up," "down," "left," "right," "vertical," "parallel," "inside," "outside," "front," and "back" are based on the direction or positional relationships shown in the drawings and are used for convenience and conciseness in describing the present invention, and do not indicate or suggest that the device or element has a specific direction or must be configured and operate in a specific direction. Therefore, they should not be interpreted as limiting the present invention.

[0075] Figure 1 is a schematic side view of a shell-and-tube reactor according to an embodiment of the present invention, and Figure 2 is a schematic top view thereof. As shown in Figures 1 and 2, the shell-and-tube reactor according to an embodiment of the present invention includes the following:

[0076] Reaction conduit 9; carbon dioxide epoxy compound mixing heat transfer unit (including a gas distributor 6 located at the top of the reaction conduit); solid-liquid mixing unit (including a mixer 8 located inside the reaction conduit and below the gas distributor 6); temperature control unit (including a first temperature sensor 2 located at the top of the reaction conduit, a second temperature sensor 3 located in the middle of the reaction conduit, a third temperature sensor 4 located at the bottom of the reaction conduit, a jacket 7 covering the outside of the reaction conduit, and a heat transfer medium 13 filled between the reaction conduit and the jacket); circulation control unit (including a density sensor 10 and a circulation device 11 located at the outlet at the lower end of the reaction conduit); pressure control unit (including an auxiliary gas port 1 located at the inlet at the upper end of the reaction conduit). Multiple reaction conduits are connected in parallel, and reaction materials are sent to each of the multiple reaction conduits via a liquid distributor 5 and connecting conduits 12.

[0077] To ensure sufficient mixing of the raw materials and prevent excessive expansion of molecular weight distribution and explosive polymerization due to reaction heterogeneity, a reaction preparation step is necessary before introducing the solid-liquid reactants into a shell-and-tube reactor. Specifically, under a carbon dioxide atmosphere of 0.1 to 0.5 MPa, the raw epoxy compounds are introduced from the storage tank via a purification system into a raw material mixing device, and then a chain transfer agent and catalyst are added and thoroughly mixed with the raw epoxy compounds. The premixing temperature range is 0 to 60°C, the pressure range is 0.1 to 2 MPa, and the premixing time is 1 to 4 hours. The raw material mixing device includes, but is not limited to, premixing vessels, venturi tubes, etc. At this point, only physical mixing occurs in the raw material mixing device, ensuring sufficient dissolution and mixing of the reactants, and no polymerization or catalyst activation reactions occur.

[0078] The premixed raw materials are introduced into the reaction pipeline from the inlet by a metering pump at a temperature of 40°C and a carbon dioxide pressure of 0.1-2 MPa. After a predetermined amount of raw materials has been introduced into the reaction pipeline, the supply is stopped, carbon dioxide is introduced from the air intake 1, and the circulation device is started. The initial flow rate of the circulation device 11 is set to complete one cycle in 10-20 minutes. Carbon dioxide in the raw materials is supplied from the carbon dioxide piping, and the pressure in the raw material mixing section is adjusted and maintained at 2-6 MPa by replenishing carbon dioxide. The jacket 7 adjusts the temperature of the heat transfer medium 13, controlling the material temperature in the reaction pipeline to 70-90°C. During the reaction process, the material flows from top to bottom through the reaction pipeline, first passing through the carbon dioxide epoxy compound mixing heat transfer unit, then through the solid-liquid mixing unit, then out of the reaction pipeline and sent to the liquid distributor by the circulation device, where it is further distributed to each reaction pipeline and flows from top to bottom again to complete the circulation. The data from the density sensor 10 is monitored, and 1.12 g / cm³ is obtained. 3 The reaction is considered complete when it reaches that point.

[0079] A side view of the shell-and-tube reactor is shown in Figure 1, where the upper part of the reaction conduit 9 is a carbon dioxide epoxy compound mixed heat transfer unit, and the lower part is a solid-liquid mixing unit. The gas distributor 6 in the carbon dioxide epoxy compound mixed heat transfer unit increases the contact area between the epoxy compound and carbon dioxide and extends the contact time, allowing the epoxy compound to absorb carbon dioxide while releasing heat, thereby lowering the material temperature. As carbon dioxide is consumed, the pressure in the reaction conduit decreases, so carbon dioxide is replenished from the gas supply port 1, and at the same time, the temperature in that region decreases due to the newly replenished carbon dioxide. The circulation device 11 continuously transports the material from the solid-liquid mixing unit to the carbon dioxide epoxy compound mixed heat transfer unit, and after the material temperature has decreased, it is returned to the solid-liquid mixing unit, so that the reaction raw materials and reaction products are uniformly mixed in the circulation process and explosive polymerization in the reaction process is avoided. After the reaction, the viscosity of the material increases and the flow rate in the solid-liquid mixing unit decreases, but unreacted material preferentially flows downward, so that the unreacted material can quickly re-reach the gas-liquid mixing region and receive heat transfer. The direction of the material's circulation and flow is as shown by the arrow in Figure 1.

[0080] Within the reaction tube, the temperature of the material increases in a gradient along the flow direction; that is, the reaction temperature is higher and the reaction proceeds faster as you approach the bottom. Since a faster reaction leads to a correspondingly larger rate of change in the material's density, the rate of change in material density is used as one of the indicators for controlling circulation. During the reaction process, if the material temperature in the middle region of the reaction tube (as measured by the second temperature sensor 3) exceeds 85°C, the jacket is controlled to lower the internal temperature of the reaction tube and increase the circulation rate until the internal temperature is maintained at 70-90°C. If the temperature difference between the middle and lower regions of the reaction tube (i.e., the temperature difference between the second temperature sensor 3 and the third temperature sensor 4) exceeds 5°C, the circulation rate is increased to prevent the temperature difference from exceeding 5°C. The change in density of the liquid material per minute is 0.06 g / cm³. 3 If the temperature exceeds a certain level, it indicates that the reaction rate is excessive. Carbon dioxide is then replenished to maintain the pressure in the reaction tube and increase the material circulation rate, accelerating the mixing and heat dissipation processes and preventing localized high temperatures. The collaborative action of the circulation control unit, temperature control unit, and pressure control unit, combined with the cooling function of the carbon dioxide epoxy compound mixing heat transfer unit, maintains the material temperature in the upper region of the reaction tube lower than that in the lower region. That is, the temperature of the first temperature sensor 2 is always lower than the temperature of the third temperature sensor 4. Also, the temperature difference between the material in the middle of the reaction tube and the material in the lower region of the reaction tube does not exceed 5°C (i.e., the temperature difference between the second temperature sensor 3 and the third temperature sensor 4 does not exceed 5°C). The material temperature in the reaction tube increases in a gradient along the flow direction. The arrangement of the reaction tubes 9 inside the shell-and-tube reactor is as shown in Figure 2, but is not limited thereto.

[0081] In one embodiment, the carbon dioxide epoxy compound mixed heat transfer unit is located in a gas-liquid transfer and heat transfer region, which is the upper space of the reaction conduit, and its volume is 20% or more of the reaction conduit volume.

[0082] In one embodiment, the gas distributor 6 is positioned 10 to 50 mm from the upper end of the reaction conduit 9, and the gas distributor 6 has a porous structure. Preferably, the pores are elliptical, with a major axis of 2 mm and a minor axis of 1 mm. Preferably, the porous structure has a rectangular arrangement. Preferably, the spacing between the pores of the porous structure is 3 mm.

[0083] In one embodiment, the inner diameter of the reaction conduit is 100 to 1500 mm. In the industrial production process of polycarbonate polyether polyol, if the inner diameter is too small, it directly affects the gas-liquid transfer efficiency. The gas-liquid contact area when the liquid passes through the carbon dioxide gas region is small, reducing the transfer efficiency. Not only does this prevent the acquisition of the desired polyester polyether polyol, but it also results in an excessively small carbonate chain segment ratio (see definition in Example 1), and further increases the probability of explosive polymerization due to insufficient involvement of carbon dioxide. On the other hand, if the inner diameter is too large, it directly affects the internal heat transfer efficiency. An excessively large inner diameter prevents the solid-liquid mixing unit from quickly and uniformly distributing the heat generated by the materials. This leads to an excessive temperature difference between the raw material center region and the external region within the conduit, causing an excessively wide molecular weight distribution of the product and negatively impacting product performance.

[0084] In one embodiment, the ratio of the reaction tube length L to diameter d satisfies 10 ≤ L:d ≤ 40. The heating time in the industrial production of polycarbonate polyether polyols has characteristics, and in the shell-and-tube reactor of the present invention, if the heating time of a unit volume of material is too short when the flow rate is constant, the reaction conversion rate per unit time decreases significantly. On the other hand, while a longer reaction time is required, if the heating time is too long, the polyester chain segments decompose and the product turns yellow. That is, the length of the reaction tube should not be excessively long. Furthermore, since heat is continuously generated during the reaction process and raises the temperature of the reaction system, the reactor needs to quickly dissipate the heat generated in the material. When the flow rate is constant, the liquid must circulate within a predetermined time, pass through the gas-liquid heat transfer region, and complete heat dissipation and gas-liquid transfer. Therefore, the length of the tube should not be excessively long. The reaction conduit used in the synthesis of polyester polyether polyols should have a special ratio of major to minor in order to provide the product with sufficient heating reaction time while simultaneously satisfying the requirements for gas-liquid transfer and heat dissipation.

[0085] In one embodiment, the number of reaction ducts is 2 to 8.

[0086] In one embodiment, the reaction tubes are connected in parallel, and the distance between the centers of the nearest adjacent tubes is no more than twice the diameter of the tube.

[0087] In one embodiment, the reaction conduits are independent of each other and are closed and isolated by valves. The liquid circulation path formed between each reaction conduit and the circulation control unit is identical.

[0088] In one embodiment, the circulation speed of the circulation unit is 10-20 minutes / circulation.

[0089] The reaction products include polycarbonate polyol, polyether polyol, cyclic carbonate, and unreacted starting epoxy compound. Next, the liquid product is passed through a catalytic filter to filter and recover the catalyst, and the filtrate is sent to a rectification unit. This rectification unit uses both a membrane-dropping column and a scraper evaporator. The filtrate is first distilled off using the membrane-dropping column to recover the epoxy compound in a buffer tank, and then sent to the scraper evaporator or rectification column to separate the main product, polycarbonate polyether polyol, from the by-product, cyclic carbonate. The separation rate of polyol and cyclic carbonate is 98%, and after complete separation of both, they are each packed into tanks for storage. The shell-and-tube reactor of the present invention will be further described below based on specific examples.

[0090] Example 1 8 L of propylene oxide (PO), 4 g of DMC catalyst, and a chain transfer agent in a 55:1 molar ratio (epoxy compound to chain transfer agent) were each added to a premixing vessel. After introducing 0.4 MPa of carbon dioxide, the mixture was mixed and stirred at 40°C. After stirring for 1 hour, the mixture was pressurized and introduced into an 8 L x 2 reactor array. Each individual reaction tube had a diameter of 100 mm and a total length of 1000 mm. After introducing the entire volume, carbon dioxide was introduced into the reaction tubes to reach 3 MPa, and the pressure was maintained. The circulation system was started and the flow rate was controlled to 600 g / min. Using temperature sensor 2 as an indicator of the reaction temperature, the materials were controlled to 80°C and reacted for 3 hours, resulting in a uniform density of 1.12 g / cm³. 3 The temperature rises and stabilizes. At this point, the reaction is terminated, and the temperature is lowered to remove the product. After removing the catalyst using a catalytic filtration system, the main and by-products are separated using a scraper evaporator.

[0091] The DMC catalyst in this example is a zinc-cobalt dimetallic cyanide complex catalyst obtained by reacting water-soluble metal salts of zinc and cobalt in an aqueous solvent. Specifically, predetermined amounts of cobalt salt and zinc salt, i.e., sodium cobalt thiocyanate and zinc bromide (molar ratio 1:4), are dissolved in an aqueous solvent and stirred. The aqueous solvent contains water and tert-butanol, and the mass ratio of the total mass of metal salts (cobalt salt and zinc salt) to the aqueous solvent is 1:5. Then an inorganic acid and an organic acid are added. The inorganic acid is dilute hydrochloric acid (pH=2), and the organic acid is glutaric acid, with a molar ratio of inorganic acid to organic acid of 5:1 and a molar ratio of total moles of metal salt to acid of 4:1. The mixture is stirred at a temperature of 10-100°C for several hours until a precipitate is continuously formed. The suspension is filtered by suction and dried to obtain a cake. The cake is re-sliced ​​and washed at 10-100°C using an aqueous solvent (specifically, washed at 100°C for 3 minutes), stirred for several hours, and then filtered by suction and dried to obtain the cake. These slurrying, washing, and drying steps are repeated multiple times at 10-100°C (specifically, 60°C for 6 minutes each time) until the pH of the liquid in the system reaches 6-7. The solid product is further dried under vacuum conditions at 80-100°C to obtain the final catalyst. Before use, the catalyst is processed into powder particles by mechanical grinding under anhydrous drying conditions.

[0092] The chain transfer agent in this example is selected from one or more of the following: ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, neopentyl glycol, glycerin, trimethylolpropane, trimethylolethane, 1,2,4-butanetriol, 1,2,6-hexanetriol, pentaerythritol, dipentaerythritol, succinic acid, glutaric acid, adipic acid, pimelic acid, subphosphoric acid, azelaic acid, sebacic acid, dodecanedioic acid, terephthalic acid, isophthalic acid, phthalic acid, trimellitic acid, pyromellitic acid, catechol, resorcinol, and hydroquinone.

[0093] In this example, the epoxy compound is selected from at least one of ethylene oxide, propylene oxide, butylene oxide, and epichlorohydrin, and specifically, propylene oxide (PO) is used as the epoxy compound.

[0094] To meet downstream polyurethane synthesis requirements, synthesized polycarbonate polyether polyols must satisfy specific quality criteria, and their quality is primarily evaluated from two aspects: molecular weight distribution and ester content. Of these, molecular weight distribution is expressed by the polymer molecular weight polydispersity index (PDI), and ester content is expressed by the carbonate chain segment ratio. A narrower molecular weight distribution, i.e., a lower PDI, indicates fewer low-molecular-weight substances and a smaller impact on the reaction rate in downstream polyurethane synthesis. On the other hand, a higher lipid (ester) content, i.e., a higher carbonate chain segment ratio, results in better carbon dioxide fixation, but excessively high levels can affect the requirements for the soft and hard segments in polyurethane synthesis. The quality grade of polycarbonate polyether polyols is classified based on the evaluation indices, PDI and carbonate chain segment ratio. A PDI of 2 or less and a carbonate chain segment ratio of 50-65% are considered acceptable, while a PDI of 1.5 or less and a carbonate chain segment ratio of 55-60% are considered superior.

[0095] Sampling analysis will be performed on the purified products. Specifically, polymerization reaction products (polycarbonate polyether polyol, cyclic carbonate propylene, and unreacted epoxy compound) will be collected in containers, and the polymerization reaction logistics samples will be analyzed. 1 Characterization is performed using 1H NMR, and the ratio of polymers to cyclic low molecules in the crude product is calculated. After purifying the polymers, the product is then re-processed. 1 1H NMR measurements are performed to calculate the ratio of polycarbonate chain segments to polyether chain segments on the polymer backbone (i.e., the carbonate chain segment ratio). The calculation method is polycarbonate chain segment / polyether chain segment, and only two types of structures, polycarbonate chain segments and polyether chain segments, exist on the polymer backbone, with the sum of their percentages being 100%.

[0096] 1The amount of carbon dioxide introduced (carbonate chain segment content) and the ratio of carbonate propylene (cyclic carbonate) to polycarbonate polyether polyol in the obtained polycarbonate polyether polyol were measured by 1H NMR (Bruker, DPX400, 400 MHz; pulse program zg30; waiting time d1: 10 s; 64 scans). Under each condition, the sample was dissolved in deuterated chloroform. 1 The relevant resonances in 1H NMR (TMS = 0 ppm reference) are as follows.

[0097] 5.0 ppm and 4.2 ppm are attributed to the proton peaks of methine and methylene on the carbonate chain segment, 4.9 ppm, 4.5 ppm and 4.1 ppm are attributed to the proton peaks of methine and methylene in the five-membered ring carbonate, and 3.5 - 3.8 ppm is attributed to the proton peak of the ether chain segment. The ppm value with the subscript of capital letter A is the integrated area (Area) of the peak at that ppm. For example, A5.0 represents the integrated area of the peak at 5.0 ppm.

[0098] Based on the 1H NMR spectrum of the crude copolymerization product 1 and the integrated areas of the relevant proton peaks, the calculation formulas for the carbonate chain segment ratio (molar ratio) (FCO2), mass fraction of cyclic carbonate content (WPC), and amount of carbon dioxide introduced (MCO2) in the copolymerization reaction are as follows. JPEG2026085883000003.jpg42137

[0099] [[ID=IS]]Here, the coefficient 44 is the molar mass of CO2, the coefficient 58 is the molar mass of PO, and the coefficient 102 is the sum of CO2 (molar mass 44 g / mol) and PO (molar mass 58 g / mol).

[0100] The calculation formula for the product conversion rate is n = m×(1 - M CO2 ) / (M - m×M CO2 ), where m is the product mass after removing cyclic carbonate propylene, and M is the total sample containing cyclic carbonate propylene.

[0101] The polymer number-average molecular weight (Mn) and polymer molecular weight polydispersity index (PDI) are measured by gel permeation chromatography (GPC).

[0102] The data is shown in Table 1.

[0103] Table 1 From the data of Example 1, the shell-and-tube reactor of the present invention can sufficiently react the raw materials at 80°C, and the resulting polycarbonate polyether polyol has a narrower molecular weight distribution (PDI = 1.13) and a good carbonate chain segment ratio in the range of 55-60%, meaning that it satisfies the application requirements while having a high carbon dioxide fixation rate. Furthermore, the reaction time is short, requiring only 3 hours to reach the predetermined conversion rate. The shell-and-tube reactor can synthesize high-quality polycarbonate polyether polyol with a conversion rate of over 95%, PDI < 1.5 (narrow molecular weight distribution), and a carbonate chain segment ratio of 55-60% after a single, concentrated input.

[0104] The following is a word-for-word translation of the text you provided, using the style of Japanese patent specifications (plain form, "~is" style). Tables A-C have been replaced with Japanese headings and item names, and numerical values ​​and conditions are listed as they appeared in the original text. [Examples 2-12] Example 2 was conducted under the same conditions as Example 1, with the only difference being that the amount of propylene oxide added was 12.8 L, meaning the gas-liquid volume ratio was 1:4.

[0105] Example 3 is identical to Example 1 in terms of conditions, the only difference being that Apparatus 2 was used and the pipe diameter was set to 220 mm.

[0106] Example 4 is identical to Example 1 in terms of conditions, the only difference being that apparatus 3 was used and the pipe diameter was set to 1500 mm.

[0107] Example 5 was identical to Example 1 in terms of conditions, the only difference being that apparatus 4 was used, there were four reaction tubes, and the amount of propylene oxide added was 16 L.

[0108] Example 6 was identical to Example 1 in terms of conditions, the only difference being that apparatus 5 was used, the reaction tubes were increased to 8, and the amount of propylene oxide added was 32 L.

[0109] Example 7 was identical to Example 1 in terms of conditions, the only difference being that apparatus 6 was used and the ratio of the major axis to the major axis of the pipe was set to 20:1.

[0110] Example 8 was identical to Example 1 in terms of conditions, the only difference being that apparatus 7 was used and the ratio of the major axis to the major axis of the pipe was set to 40:1.

[0111] Example 9 followed the same conditions as Example 1, with the only difference being that the reaction temperature was set to 70°C.

[0112] Example 10 followed the same conditions as Example 1, with the only difference being that the reaction temperature was set to 90°C.

[0113] Example 11 followed the same conditions as Example 1, with the only difference being that the initial circulation velocity was maintained at 10 minutes / circulation.

[0114] Example 12 followed the same conditions as Example 1, with the only difference being that the initial circulation velocity was maintained at 15 minutes / circulation.

[0115] The reaction apparatus and reaction conditions for each embodiment are shown in Tables A and B, where Temperature 1, Temperature 2, and Temperature 3 represent the material temperatures in the upper, middle, and lower parts of the reaction conduit, respectively.

[0116] Table A (Configuration of the reaction apparatus) JPEG2026085883000005.jpg65170 Table B (Reaction conditions for each example) The products obtained in Examples 2 to 12 were tested according to the method of Example 1, and the results are shown in Table C.

[0117] Table C (Reaction Results) JPEG2026085883000007.jpg96170 As shown in Table C, the reaction results for each example show that in Examples 1 and 3-12 the gas-liquid ratio was 1:1, meaning the volume of the gas-liquid transfer and heat transfer region was 50% of the reaction conduit volume, whereas in Example 2 the CO2 volume occupancy ratio was reduced (the gas-liquid transfer and heat transfer region volume ratio was reduced to 20%). No significant changes were observed in the molecular weight, molecular weight distribution, or ester / ether ratio of the products. Therefore, the volume of the gas-liquid transfer and heat transfer region in the shell-and-tube reactor of the present invention is 20% or more of the reaction conduit volume.

[0118] Compared to Example 1, Examples 3 and 4 increased the inner diameter of the reaction tubes, Examples 5 and 6 increased the number of reaction tubes, and Examples 7 and 8 used reaction tubes with a larger diameter-to-length ratio. Although Examples 3 to 8 are all industrial scale-ups of shell-and-tube reactors, no significant fluctuations were observed in indicators such as polymer molecular weight, molecular weight distribution, and conversion rate from the reaction process and product results. Since the molecular weight difference index is small and the molecular weight distribution is narrow, products of equivalent quality were obtained. This indicates that the shell-and-tube reactor of the present invention does not have a scale-up effect (enlargement effect). Therefore, when scaling up the reaction, it is sufficient to increase the number of parallel reaction tubes and increase the circulation pump flow rate accordingly, and no process adjustments are required, making it suitable for industrial production. In addition, the parallel reaction tubes in the present invention can share common heating equipment, and energy consumption can be reduced simultaneously with scale-up.

[0119] From the data of Examples 9, 10 and Example 1, it can be seen that the shell-and-tube reactor of the present invention can synthesize high-quality products at 70-90°C. In Examples 1-10, high-quality products were obtained by maintaining the material temperature at the top of the reaction tube lower than that at the bottom, and keeping the material temperature difference between the middle and bottom of the reaction tube within 5°C during the reaction process. From the data of Examples 11, 12 and Example 1, it can be seen that the shell-and-tube reactor of the present invention can synthesize high-quality products under conditions where the circulation rate is maintained at 10-20 minutes / circulation.

[0120] [Comparative Examples 1-7] Comparative Example 1 was identical to Example 1 in terms of conditions, the only difference being that the amount of propylene oxide added was 13.3 L, meaning the gas-liquid volume ratio was 1:5.

[0121] Comparative Example 2 had the same conditions as Example 1, the only difference being that the initial flow rate was 5 minutes / circulation.

[0122] Comparative Example 3 had the same conditions as Example 1, the only difference being that the initial flow rate was 25 minutes / circulation.

[0123] Comparative Example 4 was identical to Example 1 in terms of conditions, the only difference being the use of apparatus 8 and a reaction tube diameter of 50 mm.

[0124] Comparative Example 5 was identical to Example 1 in terms of conditions, the only difference being the use of apparatus 9 and the ratio of the major axis to the reaction tube being 50:1.

[0125] Comparative Example 6 was identical to Example 1 in terms of conditions, the only difference being that apparatus 10 was used, the number of reaction tubes was 10, and the amount of propylene oxide added was 40 L.

[0126] Comparative Example 7 was conducted under the same conditions as Example 1, with the only difference being that the difference between temperature 2 and temperature 3 during the reaction exceeded 5°C.

[0127] The reaction apparatus and reaction conditions for each comparative example are shown in Tables D and E.

[0128] Table D (Configuration of the reaction apparatus) JPEG2026085883000008.jpg33170 Table E (Reaction conditions for each comparative example) The products obtained in Comparative Examples 1 to 7 were tested according to the method of Example 1, and the results are shown in Table F.

[0129] Table F (Reaction results of comparative examples) Figure 3 compares the density change curves of polycarbonate polyether polyols in Example 1 and Comparative Examples 1-7.

[0130] Comparative Example 1 differed from Example 1 in its gas-liquid ratio, reducing the volume of the gas-liquid heat transfer region. As a result, effective mass and heat transfer of the material was not possible, leading to a broader molecular weight distribution and a decrease in ester content.

[0131] Comparative Example 2 differed from Example 1 in its initial circulating flow rate. When the flow rate was high, the material temperature inside the tube remained in a low range, the reaction rate decreased, the reaction time was extended, and as a result, the molecular weight distribution became wider.

[0132] Similarly, in Comparative Example 3, the slow flow rate kept the material temperature inside the tube in a high range, increasing the reaction rate, reducing the involvement of CO2, decreasing the ester content, and making it easier to induce explosive polymerization.

[0133] In Comparative Example 4, because the reaction tube diameter was 50 mm (less than 100 mm), the ester content in the polyol was low, the molecular weight distribution was broad, and the conversion rate was also reduced.

[0134] In Comparative Example 5, the ratio of the reaction tube's major axis to its major axis was 50, which led to non-uniform mixing of the materials and a decrease in gas-liquid transfer and heat transfer efficiency. As a result, the ester content of the polyol decreased and the molecular weight distribution broadened.

[0135] In Comparative Example 7, without controlling the temperature difference to 5°C or less, the temperature in the lower part of the reaction tube became 8°C higher than in the middle part, causing explosive polymerization to occur and the temperature to rise rapidly, reaching 95°C in the middle of the reaction tube. As a result, it was not possible to synthesize high-quality polycarbonate polyether polyols with a PDI of 2 or less.

[0136] As is clear from the density growth curves, in Comparative Examples 1-7, if the density growth is too fast during the synthesis of polycarbonate polyether polyols, the internal temperature fluctuations become large, and the quality of the resulting polyol deteriorates. Conversely, if the density growth is too slow, the reaction time is prolonged, and the molecular weight distribution becomes broader.

[0137] In this study, the density changes in Comparative Example 6 and Example 1 were similar. However, even though the conditions were identical, the number of reaction ducts was too high at 10, which led to an expansion of the molecular weight difference between each duct, resulting in a broader molecular weight distribution.

[0138] Therefore, the optimal number of reaction ducts in this invention is 2 to 8.

[0139] Finally, it should be added that the above embodiments are for the purpose of illustrating the technical content of the present invention and are not intended to limit it.

[0140] Although the present invention has been described in detail based on the above preferred embodiments, those skilled in the art can make technical modifications or equivalent substitutions without departing from the spirit and scope of the invention. [Explanation of symbols]

[0141] 1: Air intake port, 2: First temperature sensor, 3: Second temperature sensor, 4: Third temperature sensor, 5: Liquid distributor, 6: Gas distributor, 7: Jacket, 8: Mixer, 9: Reaction conduit, 10: Density sensor, 11: Circulation device, 12: Connecting conduit, 13: Heat transfer medium

Claims

1. A shell-and-tube reactor for synthesizing polycarbonate polyether polyols, It is equipped with a reaction tube, and furthermore, the following (1) to (5) (1) A carbon dioxide epoxy compound mixed heat transfer unit located at the top of the reaction tube to lower the material temperature, (2) A solid-liquid mixing unit located within the reaction conduit and below the carbon dioxide epoxy compound mixing heat transfer unit, (3) A circulation control unit for circulating and flowing materials within the reaction pipeline. (4) Temperature control unit for controlling the temperature inside the reaction tube, (5) Pressure control unit for controlling the pressure inside the reaction tube, Equipped with, The circulation control unit, temperature control unit, and pressure control unit work together to control the entire reaction process, specifically After introducing the epoxy compound, chain transfer agent, and catalyst into the reaction conduit by a single, concentrated injection, The circulation control unit transports the material in the solid-liquid mixing unit to the carbon dioxide epoxy compound mixed heat transfer unit. After the material temperature has decreased, it is returned to the solid-liquid mixing unit. The circulation control unit adjusts the material circulation speed, and the temperature control unit and pressure control unit also adjust, The material temperature at the top of the reaction tube is kept lower than the material temperature at the bottom. Maintain a temperature difference of 5°C or less between the materials in the middle and lower parts of the reaction tube. The temperature of the material inside the reaction tube gradually increases along the flow direction, creating a temperature gradient. A shell-and-tube reactor characterized in that the ratio of the major axis to the reaction tube, L:d, is less than 50.

2. The temperature control unit includes temperature sensors that indicate the material temperature in three different regions: upper, middle, and lower within the reaction conduit. Jacket for heating or cooling reaction tubes, The shell-and-tube reactor according to claim 1, further comprising a heat transfer medium filled between the jacket and the reaction tube.

3. If the temperature in the middle region of the reaction tube exceeds the reaction temperature threshold, the temperature control unit is adjusted to lower the temperature inside the reaction tube. The material circulation rate and the carbon dioxide gas replenishment rate are increased, and the temperature in the middle of the reaction tube is maintained within the reaction temperature threshold range. Furthermore, if the temperature difference between the middle and lower regions of the reaction tube exceeds the temperature difference threshold, the circulation rate and the aeration rate will be increased. The shell-and-tube reactor according to claim 1, characterized in that the temperature difference does not exceed a threshold.

4. Controlling the entire reaction process means that when the density change of the material per minute exceeds the density change rate threshold, The shell-and-tube reactor according to claim 1, characterized by including increasing the material circulation rate and the carbon dioxide gas replenishment rate so that the density change rate does not exceed a threshold.

5. The gas distributor is positioned 10 to 50 mm from the upper end of the reaction tube. The shell-and-tube reactor according to claim 1, characterized in that the gas distributor has a porous structure.

6. The shell-and-tube reactor according to claim 1, characterized in that the inner diameter of the reaction tube is 100 to 1500 mm.

7. The shell-and-tube reactor according to claim 1, characterized in that the ratio of the major axis to the reaction tube L:d satisfies 10 ≤ L:d ≤ 40.

8. The shell-and-tube reactor according to claim 1, characterized in that the number of reaction tubes is 2 to 8.

9. The shell-and-tube reactor according to claim 8, characterized in that the reaction tubes are connected in parallel and the distance between adjacent tubes is less than or equal to twice the diameter of the tubes.

10. The shell-and-tube reactor according to claim 9, characterized in that the reaction tubes are independent of each other and can be closed or isolated by valves.

11. The shell-and-tube reactor according to claim 10, characterized in that the material circulation path formed between each reaction conduit and the circulation unit is the same.

12. The shell-and-tube reactor according to claim 1, characterized in that the circulation rate of the circulation control unit is 10 to 20 minutes / circulation.

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