Method for producing polyether polyol

Abstract

The present invention relates to the technical field of polyether polyol production. Particularly disclosed is a method for producing a polyether polyol. In the method, by directly using a small molecular alcohol (such as glycerin, propylene glycol and dipropylene glycol) as an initiator, polymerization with propylene oxide / ethylene oxide is performed under the action of a bimetallic catalyst, so as to obtain a polyether polyol having a narrow molecular weight distribution and a low unsaturation degree. During the feeding process, the raw materials are distributed by means of using a jet distributor during feeding, and a circulating material and a catalyst slurry are subjected to jet feeding by means of using a nozzle design at the top of a reactor, thereby improving the conversion rate of reaction monomers, and reducing the three wastes generated in the step of synthesizing a low-molecular-weight polyether. The reaction is performed in a specially designed reaction device, thereby achieving continuous production, shortening the technological process, reducing the energy consumption, and lowering the production cost.

Description

A method for producing a polyether polyol

[0001] The present application is based on and claims priority to Chinese Patent Application No. 202411004768.6 filed on July 25, 2024, with the State Intellectual Property Office of China, the contents of which are incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] The present application belongs to the technical field of polyether polyol production, and in particular relates to a method for producing a polyether polyol. BACKGROUND

[0003] Soft foam polyether polyols generally have a molecular weight of between 3000-3500. Currently, the commonly used synthesis methods include alkali metal hydroxide catalytic synthesis and bimetallic catalytic synthesis. Alkali metal hydroxide has low catalytic activity, and a large amount is used. Moreover, it is alkaline, and its presence in polyether can accelerate the reaction of polyether with isocyanate, greatly affecting the foaming reaction. After the synthesis of polyether, post-treatment must be performed, i.e., the alkali metal hydroxide in the crude polyether is neutralized by an acid, and then adsorption and filtration are performed to remove the alkali metal salt, so that the polyether is close to neutral. In the post-treatment process, the acid neutralizer used can degrade the polyether polyol, producing aldehyde substances and odor impurities, affecting the quality of downstream products of the polyether polyol. In the post-treatment process, a certain amount of waste water and filter residue is also generated, and the treatment of these three waste substances increases the manufacturing cost of the polyether. The bimetallic catalyst has high activity, and is used in small amounts in the synthesis of polyether. Moreover, it is neutral, and can be left in the polyether after polymerization without being removed, greatly reducing the production process and the generation of three wastes. However, the use of the bimetallic catalyst for batch production of soft foam polyether requires the use of alkali metal hydroxide catalytic synthesis of the small molecule polyether polyol used as the starting agent, which must be removed by the post-treatment process to be used as the starting agent for polymerization, and inevitably generates some three wastes.

[0004] The batch method for producing polyether polyols has a long operation period, and the material is constantly back-mixed in the reaction system, which is not conducive to the synthesis of narrow molecular polyether, and the differences between batches make the product quality stability poor. Through the study of bimetallic catalysts, it is found that due to the high activity and high selectivity of bimetallic catalysts, a continuous process can be used to produce polyether polyols.

[0005] CN101302287A provides a new continuous method for preparing low unsaturation polyether polyol with multi-metal cyanide complex catalyst, the process flow is simple, first prepare 300-600 molecular weight polyether polyol in batch reaction device, then use it as raw material of continuous device, continuously add multi-metal cyanide complex catalyst, low molecular weight polyether polyol initiator and alkylene oxide into the reactor through pre-mixing process, reaction process and post-treatment process, continuously take out polyether polyol from the reactor, but the multi-metal cyanide complex catalyst must have high enough activity, so that the conversion rate of alkylene oxide in the polymerization reactor is higher than 50%, and the conversion rate in the curing reactor is more than 99.998%. The initiator used in the continuous process is a small molecule polyether polyol prepared in advance with potassium hydroxide catalyst. CN102585199A discloses a method for preparing polyether polyol, the catalyst, alkylene oxide and initiator are mixed in a static mixing reactor, then introduced into the main reactor from the bottom of the main reactor, the reaction temperature is controlled at 140-150℃, the reaction time is 0.5h, the polymerization reaction occurs through mass transfer and heat transfer, the obtained material is discharged from the top outlet of the main reactor to the curing kettle, the reaction temperature is controlled at 150℃, the reaction time is 0.5h, and the polyether polyol is obtained. The main reactor used in the invention is a kettle type reactor with stirring device, and the initiator used is a small molecule polyether polyol with a molecular weight of more than 200 prepared in advance with potassium hydroxide catalyst. The above-mentioned patents all use small molecule polyether polyol prepared in advance with potassium hydroxide catalyst, which inevitably produces three wastes, and the advantages of double metal catalyst are not fully utilized.

[0006] Therefore, the present application is provided. SUMMARY

[0007] In one aspect, the present application provides a method for producing polyether polyol, which directly uses small molecule alcohol as initiator to react with alkylene oxide under the action of catalyst, without using alkaline catalyst to prepare small molecule polyether polyol as initiator, thereby reducing the generation of three wastes and reducing cost.

[0008] In the second aspect, the present application provides a method for producing polyether polyol, which can stably improve the conversion rate of alkylene oxide.

[0009] In the third aspect, the present application provides a method for producing polyether polyol by using the continuous device, which can realize continuous industrial production, and the main reactor does not need to be additionally provided with stirring device.

[0010] The present application provides a method for producing polyether polyol, which comprises: 1) mixing alkylene oxide and polyol to obtain a mixture; 2) adding the mixture into a reactor to react with catalyst slurry to obtain polyether polyol; the catalyst is a double metal catalyst; preferably, the polyol is low carbon chain diol or triol.

[0011] By the above method of the present application, the high activity and high selectivity of the bimetallic catalyst are fully utilized, the catalyst is activated by controlling the reaction flow and the feed, and the polyether polyol is directly obtained by the reaction of the small molecule alcohol (such as glycerol, propylene glycol, dipropylene glycol) as the initiator and the alkylene oxide under the action of the catalyst, without using the small molecule polyether polyol prepared by the alkaline catalysis as the initiator.

[0012] In some embodiments, the alkylene oxide comprises propylene oxide and / or ethylene oxide.

[0013] Alternatively, the alkylene oxide is propylene oxide and ethylene oxide, and the mass ratio of the ethylene oxide to the propylene oxide is (0.06-0.1):1.

[0014] Alternatively, in step 1), the polyol is glycerol, and the mass ratio of the glycerol to the propylene oxide is (0.02-0.04):1. For example, the mass ratio of the glycerol to the propylene oxide is 0.03:1 or 0.035:1.

[0015] In some embodiments, the catalyst slurry is a mixture of the bimetallic catalyst and propylene glycol, and the concentration of the bimetallic catalyst in the slurry is in the range of 0.3wt%-0.6wt%. Preferably, the concentration of the bimetallic catalyst is in the range of 0.35wt%-0.5wt%. For example, the concentration of the bimetallic catalyst is 0.45wt% or 0.5wt%.

[0016] Alternatively, the mass ratio of the catalyst slurry to the propylene oxide is (0.005-0.010):1. For example, the mass ratio of the catalyst slurry to the propylene oxide is 0.07:1.

[0017] In the present application, the bimetallic catalyst is a bimetallic cyanide complex, and preferably the bimetallic cyanide complex is zinc hexacyanocobaltate.

[0018] In some embodiments, in step 2), the pressure in the reactor is in the range of 0.25-0.35MPaG, and the reaction temperature is in the range of 120-140℃.

[0019] Alternatively, the reaction time is in the range of 1-3 hours.

[0020] The method for producing the polyether polyol of the present application can be carried out by using the reactor device disclosed in the prior art, and preferably, the reaction is carried out in the following reaction device.

[0021] In the reactor of the present application, a raw material injection distributor and a catalyst slurry injector are arranged, and the catalyst slurry injector is located above the raw material injection distributor.

[0022] The raw material injection distributor is provided with through holes on the wall of the reactor, and the through holes are used for connecting the chamber of the distributor and the outside.

[0023] Optionally, the raw material injection distributor is an annular pipe, and the annular pipe is provided with through holes on the pipe wall.

[0024] The reaction material and catalyst slurry enter the reactor through the injector to form a spray, fully mix with unreacted alkylene oxide in the gas phase space of the reactor, expand the mass transfer area, promote the conversion of propylene oxide / ethylene oxide, and improve the mass transfer efficiency of the reactor.

[0025] In the above technical solution, the annular pipe is provided with a plurality of through holes on the pipe wall, the opening area of the through holes is 15%-30%, and the inner diameter of the through holes is 1-4mm.

[0026] Optionally, the annular pipe is provided with a plurality of through holes on the pipe wall, the opening area of the through holes is 18%-23%, and the inner diameter of the through holes is 2-3mm.

[0027] Optionally, the axis of the annular pipe is substantially parallel to the axis of the reactor, the through holes include a plurality of first through holes, a plurality of second through holes and a plurality of third through holes, the first through holes are distributed along the circumference of the annular pipe and are arranged towards the side of the reactor wall, the second through holes are distributed along the circumference of the annular pipe and are arranged downward, the first through holes and the second through holes are arranged alternately, and the third through holes are distributed along the circumference of the annular pipe and are arranged upward.

[0028] Optionally, the first through holes account for 25%-50% of the total area of the through holes of the annular pipe, the second through holes account for 25%-50% of the total area of the through holes of the annular pipe, and the third through holes account for 2%-10% of the total area of the through holes of the annular pipe.

[0029] Preferably, the first through holes account for 25%-50% of the total area of the through holes of the annular pipe, the second through holes account for 25%-50% of the total area of the through holes of the annular pipe, and the third through holes account for 2% of the total area of the through holes of the annular pipe.

[0030] The catalyst slurry injector is located at the top of the reactor.

[0031] The catalyst slurry injector is a nozzle.

[0032] The nozzles are arranged on the top of the reactor, and are evenly distributed along the circumference of the top of the reactor. The angle between the spraying direction of the nozzles and the top of the reactor is greater than 95°, and the nozzles are arranged to spray downward toward the wall of the reactor. The number of the nozzles is 4-18. Preferably, the number of the nozzles is 4-8. The number of the nozzles can be adjusted according to the size of the reactor.

[0033] Alternatively, the angle between the spraying direction of the nozzles and the top of the reactor is greater than 95°, and the number of the nozzles is 4-12. Preferably, the number of the nozzles is 4-6.

[0034] The nozzles are evenly distributed along the circumference of the top of the reactor. The angle between the spraying direction of the nozzles and the top of the reactor is greater than 95°, and the nozzles can cover a larger internal area of the reactor.

[0035] According to the above, the reactant material is mixed more fully, the mass transfer area is expanded, and the selectivity and conversion rate of the reaction monomer are improved. When the polyether polyol is produced by the method provided by the application, the reaction process is more complete, and less by-products are produced. The VOC value of the polyether polyol product is less than 5.0 ppm, and the VOC includes aldehydes (formaldehyde, acetaldehyde, propylene aldehyde, etc.), ketones and other substances.

[0036] In the above technical solution, the material after the reaction flows out from the bottom of the reactor, part of which flows to the secondary reactor for continuous reaction, and part of which is mixed with the catalyst slurry and then flows into the reactor again, so that the continuous production of the polyether polyol is realized.

[0037] During the continuous production, the target polyether polyol is filled in the main reactor as a starting pad, and a certain liquid level is maintained in the main reactor. The amount of propylene oxide added during the feeding process accounts for 2wt%-5wt% of the material in the main reactor. In order to better operate the actual production, the liquid level of the target polyether polyol is 20%-40% of the volume of the main reactor.

[0038] The target polyether polyol is the polyether polyol to be finally produced. For example, the viscosity (CP, 25°C) of the finally prepared polyether polyol is about 200-600.

[0039] Specifically, in the main reactor, the raw material injection distributor is located below the liquid level of the target polyether polyol, and the catalyst slurry injector is located above the liquid level of the target polyether polyol.

[0040] Alternatively, in the vertical direction, the raw material injection distributor is located at 1 / 5-1 / 4 of the liquid level of the target polyether polyol.

[0041] The material liquid level in the main reactor is controlled during the feeding process to be higher than the raw material injection distributor, so that the raw material can be mixed with the reaction liquid more fully, the flow of all raw materials and catalyst slurry is controlled to maintain a certain proportion (i.e., the amount of each reaction raw material and catalyst is controlled within a certain range), so that the polyether polyol can reach the set molecular weight range; the reaction heat during the reaction is removed through a circulating cooler to control the material temperature in the main reactor, and the residence time of the reaction material in the main reactor is controlled to enable the material to fully react.

[0042] The reacted material discharged from the main reactor is further reacted in the secondary reactor to obtain a crude product.

[0043] The temperature rise of the reacted material discharged from the main reactor in the secondary reactor is not more than 10℃.

[0044] Optionally, the reaction temperature in the secondary reactor is controlled to be 4-8℃ compared with the optimal temperature rise of the main reactor.

[0045] Optionally, the secondary reactor of the present application adopts a plug flow reactor, and in a continuous state, the parameters of the secondary reactor do not change with time, ensuring the stability and predictability of the reaction process, there is no radial velocity difference in the secondary reactor, and there is no concentration and temperature distribution in the radial direction, which is beneficial to the uniform reaction of the material, avoids back mixing of the material, improves the selectivity of the reaction monomer and the purity of the product, and the conversion rate of the alkylene oxide after further reaction in the secondary reactor can reach 99.99%.

[0046] In the plug flow reactor, the material flowing through the reactor flows forward in the same direction at the same speed, like a piston pushing forward in the reactor.

[0047] The crude product continuously flows out of the secondary reactor to a stripping tower, and the by-products are stripped and removed under vacuum using nitrogen, and the polyether polyol after removing the by-products flows to a product receiving tank at the bottom of the tower, and after cooling in the receiving tank, other additives are added to obtain a polyether polyol product.

[0048] After adopting the above technical scheme, the present application has the following beneficial effects compared with the prior art.

[0049] The technical scheme provided by the present application can directly use small molecule alcohol as a starter by special design of the reaction process and feeding control, shortens the process flow, reduces the generation of three wastes, and reduces energy consumption.

[0050] The reactor with a spraying device provided by the present application increases the mass transfer area, improves the conversion rate of the reaction monomer, improves the mass transfer efficiency of the reactor, and the combination of the reactor and the circulating pump instead of the complex design of the stirrer and the external circulation reduces the equipment investment and operating cost.

[0051] The polyether polyol produced by the continuous device can realize continuous industrial production, reduce production cycle, avoid material back mixing in the continuous production process, be beneficial to synthesis of narrow molecular polyether polyol, and improve product quality stability.

[0052] The specific embodiments of the present application will be further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0053] The accompanying drawings, which are part of the present application, serve to further understand the present application, and the illustrative embodiments of the present application and their descriptions serve to explain the present application, but do not constitute improper limitations on the present application. Obviously, the drawings described below are only some embodiments, and other drawings can be obtained by those skilled in the art without creative labor on the basis of these drawings. In the drawings:

[0054] Fig. 1 is a process flow diagram of the polyether polyol produced by the present application;

[0055] Fig. 2 is a longitudinal planing view of the raw material injection distributor parallel to the central axis of the main reactor of the present application;

[0056] Fig. 3 is a transverse planing view of the raw material injection distributor perpendicular to the central axis of the main reactor of the present application;

[0057] Fig. 4 is a schematic diagram of the catalyst slurry injector of the present application.

[0058] Reference signs: 1 - raw material mixer; 2 - raw material injection distributor; 3 - main reactor; 31 - wall of the reactor; 4 - main reactor circulator; 5 - catalyst slurry mixer; 6 - auxiliary reactor; 7 - stripping tower; 8 - product receiving tank; 9 - product receiving tank; 10 - product cooler; 11 - catalyst slurry injector; 12 - through hole.

[0059] It should be noted that these drawings and written descriptions are not intended to limit the scope of the concept of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0060] In order to make the purpose, technical scheme and advantages of the embodiments of the present application more clear, the technical scheme in the embodiments will be clearly and completely described below with reference to the drawings in the embodiments of the present application. The following embodiments are used to illustrate the present application, but not to limit the scope of the present application.

[0061] Referring to Fig. 1, a reaction device for producing polyether polyol according to the present application, a main reactor 3 is connected with a raw material mixer 1, a side reactor 6, a stripping column 7 and product receiving tanks 8, 9, a product cooler 10 in sequence through pipes. A main reactor circulating cooler 4, a catalyst slurry mixer 5 and the main reactor 3 are connected in sequence through pipes to form a circulating loop.

[0062] Oxidized olefins and initiators are mixed in the raw material mixer 1 and are delivered to the main reactor 3 below the liquid level of the target polyether polyol previously added in the main reactor 3, preferably, at 1 / 5-1 / 4 of the liquid height, and react under the catalysis of catalyst slurry. The reacted material flows out from the bottom of the main reactor 3, part of the circulated reacted material is sent back to the main reactor 3 after mixing with catalyst slurry in the catalyst slurry mixer 5 through the main reactor circulating cooler 4; the other part flows to the side reactor 6, where it is continuously converted to obtain a crude product. The crude product continuously flows out to the stripping column 7, where it is stripped to remove by-products under vacuum using nitrogen and then flows out from the bottom to the product receiving tanks 8, 9. The material in the product receiving tanks 8, 9 is cooled using the product cooler 10 and then antioxidant is added to obtain the polyether polyol product.

[0063] Referring to Fig. 1, the main reactor 3 is a cylindrical container with a discharge port at the bottom. The main reactor 3 is provided with a raw material injection distributor 2 and a catalyst slurry injector 11, which is located above the raw material injection distributor 2 and above the liquid level of the target polyether polyol previously added. The raw material injection distributor 2 is connected with the raw material mixer 1 through a pipe, and the catalyst slurry injector 11 is connected with the catalyst slurry mixer 5 through a pipe. Optionally, the raw material injection distributor 2 is located at a position that is half way between the liquid level of the target polyether polyol previously added and the bottom of the reactor.

[0064] Referring to Figs. 2 and 3, the raw material injection distributor 2 is an equidiameter annular pipe, the plane of which is perpendicular to the central axis of the main reactor 3. The pipe is laid along the inner wall of the reactor, and has a plurality of through holes 12, which are nozzles with an inner diameter of 1-4 mm. 20-50 nozzles are designed to spray liquid horizontally along the side of the annular pipe; 20-50 nozzles are arranged alternately with the nozzles spraying liquid horizontally to spray liquid downward; and 2 nozzles are arranged to spray liquid upward. The delivery pipe passes through the wall 31 of the main reactor 3 to communicate with the raw material injection distributor 2.

[0065] Referring to Fig. 4, the catalyst slurry injector 11 is a nozzle arranged at the top of the main reactor 3. The nozzles are symmetrically distributed according to the circumference of the reactor, and the angle between the spraying direction of the nozzles and the top of the reactor is greater than 95° to spray downward toward the wall of the reactor. The number of nozzles in the drawing is 4.

[0066] The catalyst slurry injector injects the catalyst slurry from the top to the center of the reactor, which makes the catalyst slurry form a spray after entering the reactor, and fully mixes with the unreacted alkylene oxide in the gas phase space of the reactor. The nozzles of the raw material injection distributor inject the raw material into the material in the reactor from multiple directions, which makes the newly entered raw material quickly and fully mix with the material in the reactor. These two injection methods increase the reaction area compared to the traditional stirring, promote the conversion of propylene oxide / ethylene oxide, and reduce the occurrence of side reactions.

[0067] The double metal cyanide complex catalyst used in Examples 1-3 and Comparative Example 1 below was purchased from Huai'an Bad Company. In the examples, the 20%-40% liquid level is the ratio of the volume of the polyether polyol in the reactor to the volume of the reactor.

[0068] Example 1

[0069] Preparation of polyether polyol product in combination with the continuous polyether polyol preparation device shown in Figure 1

[0070] 1) Mix propylene oxide, ethylene oxide and glycerol in a mass ratio of glycerol to propylene oxide of 0.035 and a mass ratio of ethylene oxide to propylene oxide of 0.085 to obtain the raw material for reaction;

[0071] 2) Mix the double metal catalyst and propylene glycol to obtain the catalyst slurry, and the concentration of the catalyst in the slurry is 0.5%wt;

[0072] 3) Pre-fill the target polyether polyol in the reactor to a liquid level of 40%;

[0073] 4) Pass the raw material for reaction into the reactor from a position below the liquid level of the target polyether polyol in the reactor, and add the catalyst slurry to the reactor from a position above the liquid level of the target polyether polyol, and carry out the reaction in the reactor, wherein the mass ratio of the catalyst slurry to propylene oxide is 0.007;

[0074] 5) Control the pressure of the reactor to be about 0.3 MPaG and the temperature to be 130°C, and react for 2h;

[0075] 6) After the reaction in the reactor, the material is reacted in the secondary reactor for 15 minutes at a temperature of 135°C to obtain the crude product;

[0076] 7) The crude product flows to the stripping column, the pressure in the column is less than 2kpaa, the nitrogen flow rate is 5.0kg / h, the stripping column discharge flow rate is 715kg / h, and the stripping column liquid level is maintained at 45%;

[0077] 8) The stripped off by-product material stream flows into the product receiving tank and is cooled to 50°C, antioxidant is added, and the polyether polyol product is obtained.

[0078] Example 2

[0079] The polyether polyol product is prepared in connection with the continuous polyether polyol production plant shown in Figure 1.

[0080] 1) The reaction feedstock is prepared by mixing propylene oxide, ethylene oxide and glycerol in a mass ratio of 0.03 for propylene oxide to glycerol and 0.083 for ethylene oxide to propylene oxide;

[0081] 2) The catalyst slurry is prepared by mixing the bimetallic catalyst and propylene glycol, the catalyst content in the slurry is 0.45%wt;

[0082] 3) The main reactor is pre-filled with the target polyether polyol to a liquid level of 40%;

[0083] 4) The effective volume of the main reactor is 2m 3 The reaction feedstock and the catalyst slurry are fed into the main reactor in a mass ratio of 0.007 for the catalyst slurry to propylene oxide, the total feed flow rate of the reaction feedstock and the catalyst slurry is 750kg / h, the discharge flow rate of the main reactor is 752kg / h, and the liquid level of the main reactor is maintained at 75%;

[0084] 5) The reactor pressure is controlled at about 0.3MPaG, the reaction temperature is 135°C, and the reaction time is 2 hours;

[0085] 6) The side reactor is a tubular reactor with a total volume of 0.2m 3 The material flow rate in and out of the side reactor is controlled to be consistent with the total feed flow rate, the reaction material is reacted in the side reactor for 15 minutes, the reaction temperature is 140°C, and the crude product is obtained;

[0086] 7) The crude product flows into the stripping column, the column pressure is less than 2kpaa, the nitrogen flow rate is 5kg / h, the discharge flow rate of the stripping column is 720kg / h, and the liquid level of the stripping column is maintained at 45%;

[0087] 8) The stripped off by-product material stream flows into the product receiving tank and is cooled to 50°C, antioxidant is added, and the polyether polyol product is obtained.

[0088] Example 3

[0089] The polyether polyol product is prepared in connection with the continuous polyether polyol production plant shown in Figure 1.

[0090] 1) mixing propylene oxide, ethylene oxide and glycerol in a mass ratio of 0.035 of glycerol to propylene oxide and 0.085 of ethylene oxide to propylene oxide to obtain a reaction raw material;

[0091] 2) mixing the bimetallic catalyst and propylene glycol to obtain a catalyst slurry, the concentration of the catalyst slurry being 0.45%wt;

[0092] 3) pre-filling the main reactor with a target polyether polyol to a liquid level of 40%;

[0093] 4) the effective volume of the main reactor being 1m 3 , the reaction raw material and the catalyst slurry being added to the main reactor in a mass ratio of 0.007 of the catalyst slurry to propylene oxide to carry out the reaction; the total feed flow rate of the reaction raw material and the catalyst slurry being 300kg / h, the discharge flow rate of the main reactor being 301kg / h, and the liquid level of the main reactor being maintained at 55%;

[0094] 5) the reactor pressure being controlled at about 0.3MPaG, the reaction temperature being 135°C, and the reaction time being 2.5 hours;

[0095] 6) the auxiliary reactor being a tubular reactor with a total volume of 0.1m 3 , the material in and out of the auxiliary reactor being controlled to be consistent with the total raw material feed flow rate, the reaction time of the reaction material in the auxiliary reactor being 15 minutes, and the reaction temperature being 140°C to obtain a crude product;

[0096] 7) the crude product flowing to a stripping column, the column pressure being less than 2kpaa, the nitrogen flow rate being 3.0kg / h, the discharge flow rate of the stripping column being 300.5kg / h, and the liquid level of the stripping column being maintained at 50%;

[0097] 8) the material stripped of by-products flowing into a product receiving tank and being cooled to 50°C to obtain a polyether polyol product.

[0098] Comparative Example 1

[0099] The reaction device of the present comparative example basically refers to FIGS. 1-3, except that the continuous reaction device of the present comparative example has a stirring device in the main reactor, the stirring speed being 35r / min, and there is no catalyst slurry injection device

[0100] 1) mixing propylene oxide, ethylene oxide and glycerol in a mass ratio of 0.03 of glycerol to propylene oxide and 0.085 of ethylene oxide to propylene oxide to obtain a reaction raw material;

[0101] 2) mixing the bimetallic catalyst and propylene glycol to obtain a catalyst slurry, the concentration of the catalyst slurry being 0.45%wt;

[0102] 3) The main reactor is pre-filled with 40% of the target polyether polyol;

[0103] 4) The effective volume of the main reactor is 2m 3 The reaction raw materials and the catalyst slurry are fed into the main reactor to react at a mass ratio of catalyst slurry to propylene oxide of 0.006; the total feed flow rate of the reaction raw materials and the catalyst slurry is 500 kg / h, the discharge flow rate of the main reactor is 501.5 kg / h, and the liquid level of the main reactor is maintained at 50%;

[0104] 5) The reactor pressure is controlled at about 0.3 MPaG, the reaction temperature is 130°C, and the reaction time is 2 hours;

[0105] 6) The auxiliary reactor is a tubular reactor with a total volume of 0.2m 3 The feed and discharge flow rates of the auxiliary reactor are controlled to be consistent with the total raw material feed flow rate, the reaction raw materials are reacted in the auxiliary reactor for 13 minutes at a reaction temperature of 135°C, and a crude product is obtained;

[0106] 7) The crude product flows into the stripping column, the column pressure is less than 2 kPa, the nitrogen flow rate is 3.5 kg / h, the discharge flow rate of the stripping column is 501 kg / h, and the liquid level of the stripping column is maintained at 45%;

[0107] 8) The stripping column is used to remove the by-products, and the material is then cooled to 50°C in the product receiving tank, additives are added, and a polyether polyol product is obtained.

[0108] The polyether polyol product obtained in the above specific embodiment is tested for hydroxyl value, viscosity, unsaturation value, VOC content, and other indicators, and the results are shown in Table 1 below:

[0109] Table 1:

[0110] It can be seen from the test results that the polyether polyol product obtained by the method for producing polyether polyol provided by the application reaches the standard of the superior product specified in Plastic Polyether Polyol Part 2: Specifications (GB / T 12008.2-2010), and the product obtained in Examples 1-3 has a VOC value less than 5.0 ppm, while the product of Comparative Example 1 has a VOC value greater than 5.0 ppm, which shows that the continuous device of the ejector provided by the application is used to replace the stirring in the reactor, so that the reaction is more complete, less by-products are produced, and the polyether polyol product has low odor or even no odor. In Table 1, the determination methods of the hydroxyl value, viscosity and unsaturation of the polyether polyol product are all the national standards adopted in the test methods specified in GB / T 12008.2-2010. The determination of the hydroxyl value adopts GB / T 12008.3-2009, and method A is used as the arbitration method; the determination of the viscosity adopts GB / T 12008.7-2010, and method A is used as the arbitration method; the determination of the unsaturation adopts GB / T 12008.6-2010, and method A is used as the arbitration method. The VOC detection method adopts headspace gas chromatography.

[0111] The above merely describes the preferred embodiments of the application and is not intended to limit the application in any form. Although the application has been disclosed as above with the preferred embodiments, the application is not intended to be limited thereto, and any skilled person in the art can make some changes or modifications to the above-mentioned technical content without departing from the technical solution of the application, and any simple modification, equivalent change and modification made on the basis of the technical essence of the application to the above embodiments are still within the scope of the application.

Claims

1. A method of producing a polyether polyol, comprising: 1) mixing alkylene oxide and polyol to obtain a mixture; 2) the mixture is added into a reactor to react with catalyst slurry to obtain polyether polyol; The catalyst is a bimetallic catalyst; The polyol is a low carbon chain diol or triol.

2. A process for producing a polyether polyol according to claim 1, characterized in that, The alkylene oxide includes propylene oxide and / or ethylene oxide.

3. A process for producing a polyether polyol according to claim 1, characterized in that, The alkylene oxide is propylene oxide and ethylene oxide, and the mass ratio of ethylene oxide to propylene oxide is (0.06-0.1):1; Preferably, in step 1), the polyol is glycerol, and the mass ratio of glycerol to propylene oxide is (0.02-0.04):

1.

4. A process for producing a polyether polyol according to any one of claims 1 to 3, characterized in that, The catalyst slurry is a mixture of bimetallic catalyst and propylene glycol, and the concentration of the bimetallic catalyst in the slurry ranges from 0.3wt% to 0.6wt%; Preferably, the concentration of the bimetallic catalyst ranges from 0.35wt% to 0.5wt% Preferably, the mass ratio of the catalyst slurry to propylene oxide is (0.005-0.010):

1. The bimetallic catalyst is a bimetallic cyanide complex, and preferably the bimetallic cyanide complex is zinc hexacyanocobaltate.

5. A process for producing a polyether polyol according to any one of claims 1 to 4, characterized in that, In step 2), the pressure in the reactor is 0.25-0.35MPaG, and the reaction temperature is 120-140℃; 6. A process for producing a polyether polyol according to any one of claims 1 to 5, characterized in that, Preferably, the reaction time is 1-3 hours. The reactor is provided with a raw material injection distributor and a catalyst slurry injector, and the catalyst slurry injector is located above the raw material injection distributor; 7. A process for producing a polyether polyol according to any one of claims 1 to 5, characterized in that, The raw material injection distributor is provided with through holes on the wall thereof, and the through holes are used to connect the chamber of the distributor with the outside; Preferably, the raw material injection distributor is an annular pipe, and the through holes are provided on the wall of the annular pipe. The opening area of the through holes is 15%-30%, and the inner diameter of the through holes is 1-4mm; 8. A process for producing a polyether polyol according to claim 7, characterized in that, Preferably, the wall of the annular pipe is provided with a plurality of through holes, the opening area of the through holes is 18%-23%, and the inner diameter of the through holes is 2-3mm; Preferably, the axis of the annular pipe is substantially parallel to the axis of the reactor, the through holes include a plurality of first through holes, a plurality of second through holes and a plurality of third through holes, the first through holes are distributed along the circumference of the annular pipe and are opened towards the side of the wall of the reactor, the second through holes are distributed along the circumference of the annular pipe and are opened downwards, the first through holes and the second through holes are arranged alternately, and the third through holes are distributed along the circumference of the annular pipe and are opened upwards; More preferably, the first through holes account for 25%-50% of the total area of the through holes of the annular pipe, the second through holes account for 25%-50% of the total area of the through holes of the annular pipe, and the third through holes account for 2%-10% of the total area of the through holes of the annular pipe; More preferably, the first through holes account for 38%-50% of the total area of the through holes of the annular pipe, the second through holes account for 38%-50% of the total area of the through holes of the annular pipe, and the third through holes account for 2% of the total area of the through holes of the annular pipe. The catalyst slurry injector is located at the top of the reactor; 9. A process for producing a polyether polyol according to claim 7 or 8, characterised in that, The catalyst slurry injector is a nozzle, and the nozzle is arranged at the top of the reactor; the nozzles are symmetrically distributed along the circumference of the reactor, the angle between the injection direction of the nozzles and the top of the reactor is greater than 95° and the nozzles are downwardly injected towards the wall of the reactor, the number of the nozzles is 4-12 or 4-18; Preferably, the number of the nozzles is 4-6 or 4-8. ​ 10. A process for producing a polyether polyol according to any one of claims 1 to 8, characterized in that, The reacted material flows out from the bottom of the reactor, part of which flows into the secondary reactor for further reaction, and part of which mixes with the catalyst slurry and then flows into the reactor again, to continuously produce the polyether polyol.

11. A process for producing a polyether polyol according to claim 9, characterized in that, The temperature rise in the secondary reactor is not more than 10℃ compared with the main reactor. Preferably, the temperature rise in the secondary reactor is controlled at 4-8℃ compared with the main reactor.

12. The method of producing a polyether polyol according to claim 7, wherein In continuous production, the main reactor is filled with the target polyether polyol, and the added propylene oxide accounts for 2wt%-5wt% of the target polyether polyol.

13. A process for producing a polyether polyol according to claim 12, characterized in that, The liquid level of the target polyether polyol is 20%-40% of the volume of the main reactor.

14. The method of producing a polyether polyol according to claim 12, wherein In the main reactor, the raw material injection distributor is below the liquid surface of the target polyether polyol, and the catalyst slurry injector is above the liquid surface of the target polyether polyol. Preferably, in the vertical direction, the raw material injection distributor is located at 1 / 5-1 / 4 of the liquid height of the target polyether polyol.

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