Microchannel reactor for synthesizing high-activity double metal cyanide catalyst and catalyst preparation method based on microchannel reactor

Abstract

The invention discloses a microchannel reactor for synthesizing a high-activity double metal cyanide catalyst and a catalyst preparation method based on the microchannel reactor. The micro-channel reactor comprises a base plate, a cover plate and a temperature control element, wherein a micro-channel, three feeding pipelines, a plurality of sleeves and a plurality of pulse water injection pipelines are arranged on the upper surface of the base plate; the feeding pipeline is communicated with the micro-channel, and a plurality of sleeves are arranged on one side of the micro-channel; the sleeve feeding hole is communicated with the pulse water injection pipeline; the lower surface of the cover plate and the upper surface of the substrate are packaged through screws. And the temperature control element is arranged on the upper surface of the substrate or the lower surface of the cover plate. By adopting the microchannel reactor to prepare the DMC double-metal cyanide catalyst, the DMC double-metal cyanide catalyst which is more controllable in composition, better in particle size uniformity, higher in amorphous content and higher in catalytic activity can be obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of double metal cyanide catalysts, and more specifically, to a microchannel reactor for synthesizing high-activity double metal cyanide catalysts and a catalyst preparation method based thereon. Background Art

[0002] Double metal cyanide (DMC) catalyst has the advantages of high catalytic activity, good selectivity, low residual amount, and low unsaturation of the obtained polyether. It has been widely used in the synthesis of polyether polyols in recent years. The preparation of DMC catalyst by liquid phase coprecipitation reaction of zinc chloride solution and potassium cobalt cyanate solution is a common method at present. Patent CN201510442732.0 uses a mixed solution of ZnCl2 and CoCl2 to react with a mixed solution of KCo(CN)6 and KFe(CN)6 to form two central molecules, which break the lattice structure and improve the catalytic activity. Patent CN201610192925.X uses hydrotalcite as a carrier, polyethylene glycol as a chelating agent, zinc chloride and metal cyanide as precursors, and reacts by dropping an aqueous solution of the central metal into a ligand substance solution. The catalyst has high reaction activity and good product selectivity. However, due to the limitations of the precipitation reaction itself, such as the obvious distribution gradients of local concentration and temperature, this will aggravate the heterogeneity of the chemical composition, particle size distribution and crystalline structure of the catalyst, thereby leading to great differences in the activity of the catalyst in subsequent applications. When preparing polyether polyols, there is often a relatively obvious dormant period, which prolongs the production time (sometimes even up to ten hours), and is also prone to various side reactions, affecting the purity of the target product. The end of the induction period is often accompanied by a rapid drop in pressure and a sharp increase in temperature, affecting production safety and stability. The molecular weight distribution of the obtained polyether is relatively wide, and even obvious tailing phenomenon occurs at high molecular weight, which makes the polyether have a higher viscosity, seriously affecting production stability.

[0003] The uniformity of the reaction is expected to be improved by using a special reaction process or a special reaction equipment. For example, in patent CN201980052752.3, in view of the obvious disadvantage of the induction period when using DMC catalysts, it is proposed to use a mixing nozzle (jet disperser) to spray the reaction to prepare the catalyst. Compared with the stirred tank, the concentration difference can be significantly reduced more quickly in this way, because a significantly larger and more uniform power density can be achieved, and the DMC catalyst prepared in this way has improved activity in the preparation of polyether polyols, reduced particle size and narrower particle size distribution. In patent CN202210548814.3, metal cyanide and water-soluble metal zinc salt solution are used to prepare catalyst powders of different sizes and uniform size under carbon dioxide atmosphere conditions. When used to catalyze the homopolymerization of alkylene oxide and the copolymerization of carbon dioxide and alkylene oxide to prepare polyethers and polycarbonates, they all show high catalytic activity, product selectivity and structural controllability.

[0004] The microchannel reaction process is becoming a hot topic in research because it can obtain DMC catalysts with more controllable composition, better particle size uniformity and higher amorphous content due to its stronger mass and heat transfer performance. However, the aggregation and precipitation between the particles of the precipitated product can easily lead to a sharp increase in the pressure drop of the micro-reaction channel, which in turn leads to blockage of the flow channel and forced cessation of the reaction, which poses a challenge to the stability of the microchannel reaction and is also a problem that needs to be solved urgently. Summary of the invention

[0005] In view of the problems existing in the above-mentioned background technology, the present invention proposes a microchannel reactor for synthesizing a high-activity double metal cyanide catalyst for precipitation reaction and containing pulsed oscillation, and a catalyst preparation method based thereon. The microchannel reactor can effectively improve the channel fluid structure, inhibit the aggregation of precipitated particles and the deposition and friction with the tube wall, control the diffusion rate of the two precursors, and optimize the actual reaction ratio, thereby avoiding local high viscosity and tube blockage in the microchannel.

[0006] In order to achieve the above-mentioned invention object, the present invention adopts the following technical scheme:

[0007] A microchannel reactor for synthesizing a high-activity double metal cyanide catalyst comprises a substrate, a cover plate and a temperature control element, wherein the upper surface of the substrate is provided with a microchannel, three feed pipes, a plurality of sleeves and a plurality of pulse water injection pipes;

[0008] The same side of the three feed pipes on the substrate is connected to one end of the microchannel to form a four-way pipe structure, and the other end of the microchannel is a discharge port;

[0009] On one side of the microchannel edge, several notches are provided as the feed inlet at one end of the sleeve, and the sleeve is arranged along the inside of the microchannel and the microchannel edge. The other end of the sleeve is connected and communicated with the microchannel; the inner diameter l of the sleeve and the inner diameter L of the microchannel should satisfy 0.01 < l / L < 0.05. If the ratio is too small, the pulse flushing effect is poor; if the ratio is too large, the solution concentration fluctuation will be large.

[0010] The feed inlet of the sleeve is connected and communicated with one end of the pulsed water injection pipeline, and the other end of the pulsed water injection pipeline is connected to the feed pump.

[0011] A sealing structure is formed between the lower surface of the cover plate and the upper surface of the substrate by encapsulating with two screws.

[0012] The temperature control element is placed on the upper surface of the substrate or the lower surface of the cover plate.

[0013] Further, the cross-sections of the feed pipeline and the microchannel of the present invention are square or rectangular, and the lengths of their respective sides are preferably 0.1 - 1 mm, and the length of the microchannel is preferably 0.05 - 0.5 m.

[0014] Further, the interval distance between every two sleeves of the present invention is the same, and 2 - 10 sleeves are arranged per meter of the microchannel side length.

[0015] Further, one temperature control element is arranged on each of the left and right sides of the upper surface of the substrate or the lower surface of the cover plate of the present invention.

[0016] Further, the materials of the substrate and the cover plate of the present invention are selected from stainless steel, alloy, ceramic or carbon silicon glass.

[0017] The present invention also provides a method for preparing the above microchannel reactor, and the specific steps include:

[0018] (1) Place the cleaned substrate on the processing bed and machine the microchannel and the feed pipeline.

[0019] (2) Sequentially place the microchannel substrate machined in step (1) into an ethanol and detergent aqueous solution ultrasonic cleaner for cleaning treatment, then soak and clean it with deionized water, and finally dry it to obtain a preliminarily processed microchannel substrate.

[0020] (3) Place the preliminarily processed microchannel substrate in step (2) on a laser processing machine, digitally program the required processing path and dimensions in the background, and perform laser processing on the microchannel wall to prepare a microchannel with a sleeve structure.

[0021] (4) Sequentially place the microchannel substrate with a sleeve structure machined in step (3) into an ethanol and detergent aqueous solution ultrasonic cleaner for cleaning treatment, then soak and clean it with deionized water, and finally dry it with a constant temperature drying oven to obtain the final microchannel reactor substrate.

[0022] (5) Then, a pulse water injection pipeline is connected to the sleeve feed port of the microchannel reactor substrate, and a temperature control element is placed on the lower surface of the cleaned cover plate or the upper surface of the microchannel reactor substrate obtained in step (4), and then the cover plate is bonded to the upper surface of the substrate, and the microchannel reactor is bonded and packaged with screws;

[0023] The mass concentration of the detergent aqueous solution in the above steps (2) and (4) is 1%.

[0024] Furthermore, in step (1) of the present invention, the processing method adopted for the substrate is micro-milling or wire cutting.

[0025] Furthermore, the present invention also provides a method for preparing a high-activity double metal cyanide catalyst using the above microreactor, which specifically comprises the following steps:

[0026] (1) preparing an aqueous solution of a cyanide-free metal salt Sol-A, an aqueous solution of a metal cyanide salt Sol-B, and an aqueous solution of an organic complexing ligand W Sol-C respectively and reacting them to form a dispersion;

[0027] The solution Sol-C must be fed through the feed pipe in the middle of the microchannel reactor, and the other two solutions are fed from the other two feed pipes respectively;

[0028] (2) separating a solid from the dispersion obtained in step (1), and then washing the separated solid with an aqueous solution of an organic complexing ligand W;

[0029] (3) Drying the solid obtained in step (2) and crushing it to obtain the high-activity double metal cyanide catalyst powder of the present invention.

[0030] Furthermore, the cyanide-free metal salt in step (1) of the present invention is preferably a compound having a structure of general formula (I):

[0031] L(H)e(I)

[0032] Wherein L is selected from the metal cation Zn 2+ , Fe 2+ , Cu 2+ 、Co 2+ 、Ni 2+ ,La 2+ Cr 2+ , Mn 2+ , preferably Zn 2+ , Fe 2+ 、Co 2 + 、Ni 2+ ; H is Cl, Br, carbonate, sulfate, oxalate, cyanate, thiocyanate, C1～4 One of carboxylate, nitrate and nitrite ions, preferably chloride; when H is sulfate, carbonate, C1-4 carboxylate or oxalate, e is 2; when H is Cl, Br, cyanate, thiocyanate, nitrite or nitrate, e is 1.

[0033] The metal cyanide salt in step (1) is preferably a compound having the general formula (II)

[0034] X f M b (CN) c (II)

[0035] Wherein X is selected from one or more metal cations of alkali metals and alkaline earth metals; M is selected from one of Fe, Co, Mn, and Ni ions, preferably Co and Fe; f, b, and c are selected to meet the requirements of positive and negative charge balance;

[0036] The organic complexing ligand W in step (1) and step (2) is a monoalcohol or a polyol, selected from any one of methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, tert-butanol, octanol, octyl alcohol, ethylene glycol, propylene glycol, glycerol, pentaerythritol, sorbitol, and mannitol; preferably tert-butanol, n-butanol, and isopropanol.

[0037] Furthermore, the highly active double metal cyanide catalyst in step (3) of the present invention is a compound of formula (III):

[0038] L a [M b (CN) c ] d ·xL(H) e ·yW(III)

[0039] Wherein L is selected from the metal cation Zn 2+ , Fe 2+ , Cu 2+ 、Co 2+ 、Ni 2+ ,La 2+ Cr 2+ , Mn 2+ , preferably Zn 2+ , Fe 2+ 、Co 2 + 、Ni 2+ ; M is selected from one of Fe, Co, Mn, Ni ions, preferably Co 3+ , Fe 3+ ; H is Cl, Br, carbonate, sulfate, oxalate, cyanate, thiocyanate, C 1～4One of carboxylate, nitrate and nitrite ions, preferably chloride ion; W is an organic complexing ligand selected from methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, tert-butanol, octanol, octadecanol, ethylene glycol, propylene glycol, glycerol, pentaerythritol, sorbitol, mannitol. Preferably tert-butanol, n-butanol, isopropanol; the selection of a, b, c, d, e meets the requirement of positive and negative charge balance; the value range of x is 0.5 to 2; the value range of y is 1 to 3.

[0040] Furthermore, the specific method of step (1) in the present invention includes:

[0041] (i) Weigh a certain amount of non-cyanide metal salt and deionized water at room temperature, stir and dissolve to obtain solution Sol-A, and the mass concentration of the non-cyanide metal salt in Sol-A is 5-10%;

[0042] (ii) Weigh a certain amount of metal cyanide salt and deionized water at room temperature, stir and dissolve to obtain solution Sol-B, and the mass concentration of the metal cyanide salt in Sol-B is 3-5%;

[0043] (iii) Weigh a certain amount of organic complexing ligand W and deionized water at room temperature, stir and dissolve to obtain solution Sol-C, and the mass concentration of the organic complexing ligand W in Sol-C is 5-15%;

[0044] (iv) Pump Sol-A, Sol-B, and Sol-C into the microchannel reactor simultaneously, and solution Sol-C must be fed through the feed pipe in the middle of the microchannel reactor; react in the microchannel reactor, and the volume flow ratio of Sol-A and Sol-B pumped into the microchannel reactor is 1:1, and the volume flow ratio of Sol-C to Sol-A / Sol-B pumped into the microchannel reactor is 2.5:1 to 5:1; control the temperature in the microchannel to be 50-80 °C during the pumping process. At the same time, control the residence time T of the reaction materials in the microchannel to be 0.1-1 min through the feeding device of the microchannel reactor itself, and inject deionized water for s seconds every S seconds using a pulsed feeding pump, and it should satisfy 1 < T / S < 5 and 10 < T / s < 50;

[0045] (v) The liquid after the reaction continuously flows into the collection tank from the outlet of the microchannel.

[0046] Furthermore, the step (2) of the present invention can separate the solid from the dispersion by known techniques, such as centrifugation or filtration, and can be applied by a vacuum filter, a pressure filter, a filter press, a drum filter or a disc filter. The separated solid is preliminarily washed with a mixture of an organic complexing ligand W and water in a mass ratio of 1:1, the preliminarily washing is repeated 1-3 times, and then the organic complexing ligand W is used for deep washing until the potassium ion content in the filtrate is less than 5 ppm.

[0047] Furthermore, in step (3) of the present invention, the separated and washed solid is dried at a temperature of usually 20-100° C. and under reduced pressure, and then crushed to obtain catalyst powder.

[0048] Compared with the prior art, the present invention has the following beneficial effects:

[0049] The special microchannel structure prepared by the present invention can effectively improve the fluid mechanics properties, inhibit the aggregation of precipitated particles and the deposition and friction with the tube wall. The microchannel reactor can control the diffusion rate of the two precursors, optimize the actual reaction ratio, and have high mass transfer and heat transfer efficiency. A DMC double metal cyanide catalyst with more controllable composition, better particle size uniformity, higher amorphous content and thus higher catalytic activity can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 It is a schematic structural diagram of the microchannel reactor described in the present invention.

[0051] Figure 2 It is a schematic diagram of the combined structure of the microchannel, sleeve and pulse water injection pipeline of the present invention.

[0052] Figure 1-2 The markings in the figure are: 1 cover plate, 2, 3, 4 feed pipes, 5 pulse water injection pipe, 6 casing, 7 base plate, 8, 9 temperature control elements, 10 microchannel. DETAILED DESCRIPTION

[0053] The present invention will be described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form.

[0054] (I) Preparation of microchannel reactor

[0055] Example 1

[0056] like Figure 1 As shown, a microchannel reactor for synthesizing a high-activity double metal cyanide catalyst proposed by the present invention comprises a cover plate 1, feed pipes 2, 3, 4, a pulse water injection pipe 5, a sleeve 6, and base plates 7, 8, 9 temperature control elements.

[0057] The preparation method of the microchannel reactor is:

[0058] (1) A copper block of 150 mm (length) × 10 mm (width) × 10 mm (thickness) was cut off, and the surface stains were removed with deionized water and placed in a constant temperature drying oven for drying. The copper block microchannel substrate 7 was placed on a micro-milling machine, and a 0.1-0.2 mm micro-milling cutter was used to machine a micro-channel of 100 mm (length) × 0.2 mm (width) × 0.2 mm (thickness);

[0059] (2) The processed microchannel substrate is cleaned in ethanol and 1% detergent ultrasonic cleaning machine in turn, then soaked and cleaned with deionized water, and finally dried to obtain a pre-processed microchannel reactor;

[0060] (3) placing the pre-processed microchannel substrate on a laser processor, digitally programming the path and size to be processed (setting the gap between the sleeve and the microchannel to be 0.003 mm), using a laser beam to project a focused spot to the area to be processed for scanning, setting the laser power to 30 W and the scanning frequency to 50 times, to prepare a microchannel with a sleeve;

[0061] (4) The processed microchannel substrate is cleaned in ethanol and 1% detergent ultrasonic cleaning machine, then soaked and cleaned in deionized water, and finally dried in a constant temperature drying oven;

[0062] (5) Packaging: Cut a piece of quartz glass with a size of 150 mm (length) × 10 mm (width) × 1 mm (thickness), wash the surface stains with deionized water and dry it to serve as the cover plate 1; bond the cover plate 1 to the upper surface of the substrate 7, and bond the microchannel reactor with a bonding machine.

[0063] Example 2

[0064] like Figure 1 As shown, a microchannel reactor for synthesizing a high-activity double metal cyanide catalyst proposed by the present invention comprises a cover plate 1, feed pipes 2, 3, 4, a pulse water injection pipe 5, a sleeve 6, and base plates 7, 8, 9 temperature control elements.

[0065] The preparation method of the microchannel reactor is:

[0066] (1) A Hastelloy block of 200 mm (length) × 10 mm (width) × 10 mm (thickness) was cut off, and the stains on the surface were removed with deionized water and placed in a constant temperature drying oven for drying. The Hastelloy block microchannel substrate 7 was placed on a micro-milling machine, and a 0.1-0.2 mm micro-milling cutter was used to machine a micro-channel of 150 mm (length) × 0.15 mm (width) × 0.15 mm (thickness);

[0067] (2) The processed microchannel substrate is cleaned in ethanol and 1% detergent ultrasonic cleaning machine in turn, then soaked and cleaned with deionized water, and finally dried to obtain a pre-processed microchannel reactor;

[0068] (3) placing the pre-processed microchannel substrate on a laser processor, digitally programming the path and size to be processed (setting the gap between the sleeve and the microchannel to be 0.003 mm), using a laser beam to project a focused spot to the area to be processed for scanning, setting the laser power to 30 W and the scanning frequency to 50 times, to prepare a microchannel with a sleeve;

[0069] (4) The processed microchannel substrate is cleaned in ethanol and 1% detergent ultrasonic cleaning machine, then soaked and cleaned in deionized water, and finally dried in a constant temperature drying oven;

[0070] (5) Packaging: A piece of organic glass with a size of 200 mm (length) × 10 mm (width) × 1 mm (thickness) was cut, and the stains on the surface were washed off with deionized water and dried to form the cover plate 1. The cover plate 1 was bonded to the upper surface of the substrate 7, and the microchannel reactor was bonded and packaged using a bonding machine.

[0071] Example 3

[0072] like Figure 1 As shown, a microchannel reactor for synthesizing a high-activity double metal cyanide catalyst proposed by the present invention comprises a cover plate 1, feed pipes 2, 3, 4, a pulse water injection pipe 5, a sleeve 6, and base plates 7, 8, 9 temperature control elements.

[0073] The preparation method of the microchannel reactor is:

[0074] (1) a silicon carbide substrate of 180 mm (length) × 10 mm (width) × 10 mm (thickness) is cut off, the stains on the surface are cleaned with deionized water and the substrate is placed in a constant temperature drying oven for drying, the silicon carbide microchannel substrate 7 is placed on a micro-milling machine, and a micro-milling cutter of 0.1-0.2 mm is used to machine a micro-channel of 120 mm (length) × 0.18 mm (width) × 0.18 mm (thickness);

[0075] (2) The processed microchannel substrate is cleaned in ethanol and 1% detergent ultrasonic cleaning machine in turn, then soaked and cleaned with deionized water, and finally dried to obtain a pre-processed microchannel reactor.

[0076] (3) placing the pre-processed microchannel substrate on a laser processor, digitally programming the path and size to be processed (setting the gap between the sleeve and the microchannel to be 0.005 mm), using a laser beam to project a focused spot to the area to be processed for scanning, setting the laser power to 30 W and the scanning frequency to 50 times, to prepare a microchannel with a sleeve;

[0077] (4) The processed microchannel substrate is cleaned in ethanol and 1% detergent ultrasonic cleaning machine, then soaked and cleaned in deionized water, and finally dried in a constant temperature drying oven;

[0078] (5) Packaging: A piece of organic glass with a size of 180 mm (length) × 10 mm (width) × 1 mm (thickness) was cut, and the stains on the surface were washed off with deionized water and dried to form the cover plate 1. The cover plate 1 was bonded to the upper surface of the substrate 7, and the microchannel reactor was bonded and packaged using a bonding machine.

[0079] Example 4

[0080] like Figure 1 As shown, a microchannel reactor for synthesizing a high-activity double metal cyanide catalyst proposed by the present invention comprises a cover plate 1, feed pipes 2, 3, 4, a pulse water injection pipe 5, a sleeve 6, and base plates 7, 8, 9 temperature control elements.

[0081] The preparation method of the microchannel reactor is:

[0082] (1) A stainless steel block of 200 mm (length) × 10 mm (width) × 10 mm (thickness) was cut off, the stains on the surface were cleaned with deionized water and the block was placed in a constant temperature drying oven for drying. The stainless steel microchannel substrate 7 was placed on a micro-milling machine, and a 0.1-0.2 mm micro-milling cutter was used to machine a micro-channel of 100 mm (length) × 0.15 mm (width) × 0.15 mm (thickness);

[0083] (2) The processed microchannel substrate is cleaned in ethanol and 1% detergent ultrasonic cleaning machine in turn, then soaked and cleaned with deionized water, and finally dried to obtain a pre-processed microchannel reactor.

[0084] (3) placing the pre-processed microchannel substrate on a laser processor, digitally programming the path and size to be processed (setting the gap between the sleeve and the microchannel to be 0.003 mm), using a laser beam to project a focused spot to the area to be processed for scanning, setting the laser power to 30 W and the scanning frequency to 50 times, to prepare a microchannel with a sleeve;

[0085] (4) The processed microchannel substrate is cleaned in ethanol and 1% detergent ultrasonic cleaning machine in turn, then soaked and cleaned with deionized water, and finally dried in a constant temperature drying oven.

[0086] (5) Packaging: A piece of quartz glass of 200 mm (length) × 10 mm (width) × 1 mm (thickness) was cut, and the stains on the surface were washed off with deionized water and dried to form the cover plate 1. The cover plate 1 was bonded to the upper surface of the substrate 7, and the microchannel reactor was bonded and packaged using a bonding machine.

[0087] (II) Preparation of highly active double metal cyanide catalysts

[0088] The composition of the catalyst was determined by combining elemental analysis with ICP (inductively coupled plasma emission spectroscopy); the Zn and Co content in the catalyst was determined by an IRIS Advantage full spectrum direct reading plasma atomic emission spectrometer, and the C, H, and N elements in the catalyst were determined by an Element Vario EL elemental analyzer. The catalysts of the following synthesis examples were prepared using the microchannel reactor prepared in Example 1 above.

[0089] Synthesis Example 1 (Preparation of Catalyst DMC-1)

[0090] Prepare 100 grams of aqueous solution Sol-A (5.5 grams of ZnCl2 dissolved in 94.5 grams of deionized water), 100 grams of 3.5% K3[Co(CN)6] aqueous solution Sol-B (3.5 grams of K3[Co(CN)6] dissolved in 96.5 grams of deionized water) and 100 grams of aqueous solution Sol-C (5.5 grams of tert-butanol dissolved in 94.5 grams of deionized water), then turn on three metering pumps (Sol-C must be fed through the middle feed port), and input Sol-A, Sol-B and Sol-C solutions into the microchannel reactor system at speeds of 0.004 mL / min, 0.004 mL / min and 0.012 mL / min, respectively. During the reaction, the system temperature is controlled at 50°C, and deionized water is pulsed through the casing for 0.24 seconds every 4.8 seconds. Sol-A, Sol-B and Sol-C solutions react with each other in the microchannel and flow out into a round-bottom flask to obtain a light blue dispersion. The paste is separated by filtration and filtered under reduced pressure. The paste is initially washed with a mixture of tert-butyl alcohol (TBA) and water (150 ml of tert-butyl alcohol is dissolved in 150 ml of water). After repeated washing 3 times, it is deeply washed with tert-butyl alcohol until the potassium ion content in the filtrate is less than 5 ppm. Finally, the solid is vacuum dried and crushed to obtain the catalyst powder DMC-1. Its composition calculated by elemental analysis and ICP determination results is Zn3[Co(CN)6]2·1.33Zn(Cl)2·2.26TBA.

[0091] Synthesis Example 2 (Preparation of Catalyst DMC-2)

[0092] Prepare 100 grams of aqueous solution Sol-A (5.3 grams of ZnCl2 dissolved in 94.7 grams of deionized water), 100 grams of 3.5% K3[Co(CN)6] aqueous solution Sol-B (3.5 grams of K3[Co(CN)6] dissolved in 96.5 grams of deionized water) and 100 grams of aqueous solution Sol-C (8.3 grams of n-butanol dissolved in 91.7 grams of deionized water), then turn on three metering pumps (Sol-C must be fed through the middle feed port), and input Sol-A, Sol-B and Sol-C solutions into the microchannel reactor system at speeds of 0.003 mL / min, 0.003 mL / min and 0.009 mL / min, respectively. During the reaction, the system temperature is controlled at 50°C, and deionized water is pulsed through the casing for 0.32 seconds every 6.4 seconds. Sol-A, Sol-B and Sol-C solutions react with each other in the microchannel and flow out into a round-bottom flask to obtain a light blue dispersion. The paste is separated by filtration and filtered under reduced pressure. The paste is initially washed with a mixture of tert-butyl alcohol (TBA) and water (150 ml of tert-butyl alcohol is dissolved in 150 ml of water). After repeated washing 3 times, it is deeply washed with tert-butyl alcohol until the potassium ion content in the filtrate is less than 5 ppm. Finally, the solid is vacuum dried and crushed to obtain the catalyst powder DMC-2. Its composition calculated by elemental analysis and ICP determination results is Zn3[Co(CN)6]2·1.54Zn(Cl)2·2.35TBA.

[0093] Synthesis Example 3 (Preparation of Catalyst DMC-3)

[0094] Prepare 100 grams of aqueous solution Sol-A (6.1 grams of ZnCl2 dissolved in 93.9 grams of deionized water), 100 grams of 4.5% K3[Co(CN)6] aqueous solution Sol-B (4.5 grams of K3[Co(CN)6] dissolved in 95.5 grams of deionized water) and 100 grams of aqueous solution Sol-C (10.5 grams of isopropanol dissolved in 89.5 grams of deionized water), then turn on three metering pumps (Sol-C must be fed through the middle feed port), and input Sol-A, Sol-B and Sol-C solutions into the microchannel reactor system at speeds of 0.002 mL / min, 0.002 mL / min and 0.006 mL / min, respectively. During the reaction, the system temperature is controlled at 80°C, and deionized water is pulsed through the casing for 0.48 seconds every 9.6 seconds. Sol-A, Sol-B and Sol-C solutions react with each other in the microchannel and flow out into a round-bottom flask to obtain a light blue dispersion. The paste is separated by filtration and filtered under reduced pressure. The paste is initially washed with a mixture of tert-butyl alcohol (TBA) and water (150 ml of tert-butyl alcohol is dissolved in 150 ml of water). After repeated washing 3 times, it is deeply washed with tert-butyl alcohol until the potassium ion content in the filtrate is less than 5 ppm. Finally, the solid is vacuum dried and crushed to obtain the catalyst powder DMC-3. Its composition calculated by elemental analysis and ICP determination results is Zn3[Co(CN)6]2·1.78Zn(Cl)2·2.59TBA.

[0095] Synthesis Example 4 (Preparation of Catalyst DMC-4)

[0096] Prepare 100 grams of aqueous solution Sol-A (7.2 grams of ZnCl2 dissolved in 92.8 grams of deionized water), 100 grams of 4.2% K3[Co(CN)6] aqueous solution Sol-B (4.2 grams of K3[Co(CN)6] dissolved in 95.8 grams of deionized water) and 100 grams of aqueous solution Sol-C (9.1 grams of tert-butanol dissolved in 90.9 grams of deionized water), then turn on three metering pumps (Sol-C must be fed through the middle feed port), and input Sol-A, Sol-B and Sol-C solutions into the microchannel reactor system at speeds of 0.001 mL / min, 0.001 mL / min and 0.003 mL / min, respectively. During the reaction, the system temperature is controlled at 75°C, and deionized water is pulsed through the casing for 0.60 seconds every 12.0 seconds. Sol-A, Sol-B and Sol-C solutions react with each other in the microchannel and flow out into a round-bottom flask to obtain a light blue dispersion. The paste is separated by filtration and filtered under reduced pressure. The paste is initially washed with a mixture of tert-butyl alcohol (TBA) and water (150 ml of tert-butyl alcohol is dissolved in 150 ml of water). After repeated washing 3 times, it is deeply washed with tert-butyl alcohol until the potassium ion content in the filtrate is less than 5 ppm. Finally, the solid is vacuum dried and crushed to obtain the catalyst powder DMC-4. Its composition calculated by elemental analysis and ICP determination results is Zn3[Co(CN)6]2·1.66Zn(Cl)2·1.90TBA.

[0097] Synthesis Example 5 (Preparation of Catalyst DMC-5)

[0098] Prepare 100 grams of aqueous solution Sol-A (8.5 grams of ZnCl2 dissolved in 91.5 grams of deionized water), 100 grams of 3.5% K3[Co(CN)6] aqueous solution Sol-B (3.5 grams of K3[Co(CN)6] dissolved in 96.5 grams of deionized water) and 100 grams of aqueous solution Sol-C (7.5 grams of tert-butanol dissolved in 92.5 grams of deionized water), then turn on three metering pumps (Sol-C must be fed through the middle feed port), and input Sol-A, Sol-B and Sol-C solutions into the microchannel reactor system at speeds of 0.005 mL / min, 0.005 mL / min and 0.015 mL / min, respectively. During the reaction, the system temperature is controlled at 55°C, and deionized water is pulsed through the casing for 0.20 seconds every 4.0 seconds. Sol-A, Sol-B and Sol-C solutions react with each other in the microchannel and flow out into a round-bottom flask to obtain a light blue dispersion. The paste is separated by filtration and filtered under reduced pressure. The paste is initially washed with a mixture of tert-butyl alcohol (TBA) and water (150 ml of tert-butyl alcohol is dissolved in 150 ml of water). After repeated washing 3 times, it is deeply washed with tert-butyl alcohol until the potassium ion content in the filtrate is less than 5 ppm. Finally, the solid is vacuum dried and crushed to obtain the catalyst powder DMC-5. Its composition calculated by elemental analysis and ICP determination results is Zn3[Co(CN)6]2·1.76Zn(Cl)2·2.57TBA.

[0099] Synthesis Example 6 (Preparation of Catalyst DMC-6)

[0100] Prepare 100 grams of aqueous solution Sol-A (9.3 grams of ZnCl2 dissolved in 90.7 grams of deionized water), 100 grams of 4.5% K3[Co(CN)6] aqueous solution Sol-B (4.5 grams of K3[Co(CN)6] dissolved in 95.5 grams of deionized water) and 100 grams of aqueous solution Sol-C (12.7 grams of tert-butanol dissolved in 87.3 grams of deionized water), then turn on three metering pumps (Sol-C must be fed through the middle feed port), and input Sol-A, Sol-B and Sol-C solutions into the microchannel reactor system at speeds of 0.004 mL / min, 0.004 mL / min and 0.012 mL / min, respectively. During the reaction, the system temperature is controlled at 80°C, and deionized water is pulsed through the casing for 0.24 seconds every 4.8 seconds. Sol-A, Sol-B and Sol-C solutions react with each other in the microchannel and flow out into a round-bottom flask to obtain a light blue dispersion. The paste is separated by filtration and filtered under reduced pressure. The paste is initially washed with a mixture of tert-butyl alcohol (TBA) and water (150 ml of tert-butyl alcohol is dissolved in 150 ml of water). After repeated washing 3 times, it is deeply washed with tert-butyl alcohol until the potassium ion content in the filtrate is less than 5 ppm. Finally, the solid is vacuum dried and crushed to obtain the catalyst powder DMC-6. Its composition calculated by elemental analysis and ICP determination results is Zn3[Co(CN)6]2·1.14Zn(Cl)2·2.88TBA.

[0101] Comparative Example 1 (Preparation of Catalyst DMC-7)

[0102] Weigh 5.5 g ZnCl2 and 94.5 g deionized water in a flask, stir and dissolve to obtain solution Sol-A. Weigh 3.5 g K3[Co(CN)6], 5.5 g organic ligand tert-butyl alcohol and 91.00 g deionized water in a flask, stir and dissolve to obtain solution Sol-B. At room temperature and under vigorous stirring, slowly drip an equal amount of Sol-A into Sol-B using a peristaltic pump, the solution gradually turns from light blue to milky white, filter and separate to obtain a paste, filter under reduced pressure, use a mixture of tert-butyl alcohol (TBA) and water (150 ml tert-butyl alcohol dissolved in 150 ml water) to preliminarily wash the obtained paste, repeat the washing 3 times, and continue to wash deeply with tert-butyl alcohol until the potassium ion content in the filtrate is less than 5 ppm, and finally vacuum dry the obtained solid at 40-60°C, and crush to obtain catalyst powder DMC-7. Its composition calculated by elemental analysis and ICP measurement results is Zn3[Co(CN)6]2·1.13Zn(Cl)2·2.45TBA;.

[0103] The performance parameters of the catalysts prepared in Synthesis Examples 1-6 and Comparative Example 1 are shown in Table 1 below.

[0104] Table 1 Catalyst performance parameters

[0105]

[0106] As can be seen from the above table, the catalysts (DMC-1 to DMC-6) prepared by the pulsed microchannel reactor of the present invention have little difference in degree of crystallization compared with the control sample (DMC-7) prepared by the direct stirring method, but have significantly higher specific surface area, better particle size uniformity, higher amorphous content and significantly improved catalytic activity.

Claims

1. A microchannel reactor for synthesizing a highly active double metal cyanide catalyst, characterized in that: It comprises a base plate (7), a cover plate (1) and temperature control elements (8, 9); the upper surface of the base plate (7) is provided with a microchannel (10), three feed pipes (2, 3, 4), a plurality of sleeves (6) and a plurality of pulse water injection pipes (5); The same side of the three feed pipes on the substrate (7) is connected to one end of the microchannel (10) to form a four-way pipe structure, and the other end of the microchannel is a discharge port; A plurality of notches are provided on one side of the microchannel as a feed port at one end of the sleeve (6), and the sleeve (6) is provided along the inside and the edge of the microchannel, and the other end of the sleeve (6) is connected to the microchannel (10); the inner diameter l of the sleeve and the inner diameter L of the microchannel should satisfy 0.01 <l / L<0.05; The feed port of the casing (6) is connected to one end of the pulse water injection pipeline (5), and the other end of the pulse water injection pipeline (5) is connected to the feed pump; A sealing structure is formed between the lower surface of the cover plate (1) and the upper surface of the base plate (7) by sealing with two screws; The temperature control element is placed on the upper surface of the substrate or the lower surface of the cover.

2. A microchannel reactor for synthesizing a high-activity double metal cyanide catalyst according to claim 1, characterized in that: The cross-section of the feed pipe and the microchannel is square or rectangular, the length of each side is 0.1-1 mm, and the length of the microchannel is 0.05-0.5 m; The distance between every two sleeves is the same, and 2-10 sleeves are arranged per meter of microchannel side length.

3. A microchannel reactor for synthesizing a high-activity double metal cyanide catalyst according to claim 1, characterized in that: The temperature control element is arranged one on each side of the upper surface of the substrate or the lower surface of the cover plate.

4. A microchannel reactor for synthesizing a high-activity double metal cyanide catalyst according to claim 1, characterized in that: The material of the substrate and the cover plate is selected from stainless steel, alloy, ceramic or carbon silicon glass.

5. A method for preparing the microchannel reactor according to any one of claims 1 to 4, characterized in that: The specific steps include: (1) Placing the cleaned substrate on a processing bed and processing microchannels and feed pipes; (2) placing the microchannel substrate processed in step (1) into an ultrasonic cleaning machine containing ethanol and detergent water for cleaning, then soaking and cleaning with deionized water, and finally drying to obtain a pre-processed microchannel substrate; (3) placing the microchannel substrate preliminarily processed in step (2) on a laser processor, digitally programming the path and size to be processed in the background, laser processing the microchannel wall, and preparing a microchannel with a sleeve structure; (4) placing the microchannel substrate with a sleeve structure processed in step (3) into an ethanol and detergent aqueous solution ultrasonic cleaning machine for cleaning, then soaking and cleaning with deionized water, and finally drying in a constant temperature drying oven to obtain a final microchannel reactor substrate; (5) Then, a pulse water injection pipeline is connected to the sleeve feed port of the microchannel reactor substrate, and a temperature control element is placed on the lower surface of the cleaned cover plate or the upper surface of the microchannel reactor substrate obtained in step (4), and then the cover plate is bonded to the upper surface of the substrate, and the microchannel reactor is bonded and packaged with screws; The mass concentration of the detergent aqueous solution in the above steps (2) and (4) is 1%.

6. The method for preparing a microchannel reactor according to claim 5, characterized in that: The processing method adopted for the substrate in step (1) is micro-milling or wire cutting.

7. A method for preparing a high-activity double metal cyanide catalyst using the microchannel reactor according to any one of claims 1 to 4, characterized in that: The specific steps include: (1) preparing an aqueous solution of a cyanide-free metal salt Sol-A, an aqueous solution of a metal cyanide salt Sol-B, and an aqueous solution of an organic complexing ligand W Sol-C respectively and reacting them to form a dispersion; Among them, solution Sol-C must be fed through the feed pipe in the middle of the microchannel reactor, and the other two solutions are fed through the other two feed pipes respectively; (2) Separate the solid from the dispersion obtained in step (1), and then wash the separated solid with an aqueous solution of the organic complexing ligand W; (3) Dry and pulverize the solid obtained in step (2) to obtain the high-activity double metal cyanide catalyst powder of the present invention.

8. The method according to claim 7, characterized in that: The cyanide-free metal salt described in step (1) preferably has a compound with the general formula (I) structure L(H)e(I) Wherein L is selected from the metal cation Zn 2+ , Fe 2+ , Cu 2+ 、Co 2+ 、Ni 2+ ,La 2+ Cr 2+ , Mn 2+ , H is Cl, Br, carbonate, sulfate, oxalate, cyanate, thiocyanate, C 1～4 One of carboxylate, nitrate and nitrite ions; when H is sulfate, carbonate, C1-4 carboxylate or oxalate, e is 2; when H is Cl, Br, cyanate, thiocyanate, nitrite or nitrate, e is 1; The metal cyanide salt described in step (1) preferably has a compound with the general formula (II) structure X f M b (CN) c (II) Wherein X is selected from one or more metal cations of alkali metals and alkaline earth metals; M is selected from one of Fe, Co, Mn, Ni ions, and the selection of f, b, c meets the requirement of positive and negative charge balance; The organic complexing ligand W described in steps (1) and (2) is a unit alcohol or a polyol, and is selected from any one of methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, tert-butanol, octanol, octadecyl alcohol, ethylene glycol, propylene glycol, glycerol, pentaerythritol, sorbitol, mannitol; The high-activity double metal cyanide catalyst described in step (3) is a compound of general formula (III) 50 a [M b (CN) c ] d ·xL(H) e ·yW(III) Wherein L is selected from the metal cation Zn 2+ , Fe 2+ , Cu 2+ 、Co 2+ 、Ni 2+ ,La 2+ Cr 2+ , Mn 2+ ; M is selected from one of Fe, Co, Mn, and Ni ions; H is Cl, Br, carbonate, sulfate, oxalate, cyanate, thiocyanate, C 1～4 One of carboxylate, nitrate and nitrite ions; W is an organic complexing ligand selected from methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, tert-butanol, octanol, octyl alcohol, ethylene glycol, propylene glycol, glycerol, pentaerythritol, sorbitol and mannitol. Tert-butanol, n-butanol and isopropanol are preferred; the selection of a, b, c, d and e meets the requirement of positive and negative charge balance; the value range of x is 0.5 to 2; the value range of y is 1 to 3.

9. The method according to claim 8, characterized in that: The specific method of step (1) includes: (i) Weigh a certain amount of cyanide-free metal salt and deionized water at room temperature, stir and dissolve to obtain solution Sol-A, and the mass concentration of the cyanide-free metal salt in Sol-A is 5-10%; (ii) Weigh a certain amount of metal cyanide salt and deionized water at room temperature, stir and dissolve to obtain solution Sol-B, and the mass concentration of the metal cyanide salt in Sol-B is 3-5%; (iii) Weigh a certain amount of organic complexing ligand W and deionized water at room temperature, stir and dissolve to obtain solution Sol-C, and the mass concentration of the organic complexing ligand W in Sol-C is 5-15%; (iv) Pump Sol-A, Sol-B, and Sol-C into the microchannel reactor at the same time. Among them, solution Sol-C must be fed through the feed pipe in the middle of the microchannel reactor; react in the microchannel reactor, and the volume flow ratio of Sol-A and Sol-B pumped into the microchannel reactor is 1:1, and the volume flow ratio of Sol-C to Sol-A / Sol-B pumped into the microchannel reactor is 2.5:1-5:1; control the temperature in the microchannel to be 50-80 °C during the pumping process. At the same time, control the residence time T of the reaction materials in the microchannel to be 0.1-1 min through the feeding device of the microchannel reactor itself, and inject deionized water for s seconds every S seconds using a pulsed feeding pump through the sleeve, and it should satisfy 1<T / S<5 and 10<T / s<50; (v) The liquid after the reaction continuously flows from the outlet of the microchannel into the collection tank.

10. The method according to claim 9, characterized in that: In step (2), a mixed solution with a mass ratio of organic complexing ligand W to water of 1:1 is used to preliminarily wash the separated solid. The preliminary washing is repeated 1-3 times, and then deep washing is carried out with organic complexing ligand W until the potassium ion content in the filtrate is lower than 5 ppm; In the step (3), the separated and washed solid is dried at a temperature of 20 to 100° C. under reduced pressure, and then crushed to obtain catalyst powder.

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