Method for synthesizing diethanolisopropanolamine under catalysis of solid base

Abstract

The invention discloses a method for synthesizing diethanolisopropanolamine under catalysis of solid base, which comprises the following steps: taking diethanol amine and epoxypropane as raw materials, and taking solid base as a catalyst to catalyze the diethanol amine and epoxypropane to carry out ring-opening addition reaction to synthesize the diethanolisopropanolamine, wherein the solid alkali is an Mg-Al-O composite oxide prepared by taking a liquid A and a liquid B as raw materials, preparing a hydrotalcite precursor by adopting a coprecipitation reaction, and roasting the hydrotalcite precursor; the liquid A is a mixed aqueous solution of Mg < 2 + > and Al < 3 + >, and the liquid B is a mixed aqueous solution of NaOH and Na2CO3. The solid base is used for catalyzing the diethanol amine and the epoxypropane to synthesize the diethanolisopropanolamine, the reaction activity and the DEIPA selectivity can be improved, the DEA conversion rate is larger than or equal to 98%, the DEIPA selectivity is larger than or equal to 97%, the DEIPA yield is larger than or equal to 95%, the catalyst can be repeatedly used, and the production cost and the environmental protection pressure are greatly reduced.

Description

Technical Field

[0001] This invention belongs to the field of organic synthesis, specifically relating to a method for the solid base-catalyzed synthesis of diethanol monoisopropanolamine (DEIPA). Background Technology

[0002] Diethanolamine monoisopropanolamine (DEIPA), chemically known as N-(2-hydroxyethyl)-N-isopropylethanolamine, combines the properties of ethanolamines and isopropanolamines, giving it unique performance characteristics. DEIPA acts as a grinding aid; adding it during cement grinding effectively improves grinding efficiency, reduces energy consumption, and increases cement production per hour. More importantly, compared to traditional triethanolamine and other alkanolamine grinding aids, it excels in improving strength, significantly enhancing both early and later strength of cement, and exhibits good compatibility with various cement types, resulting in significant cost-effectiveness. Furthermore, DEIPA possesses low toxicity and biodegradability, making it environmentally friendly and superior to earlier grinding aids such as formates and acetates. DEIPA can also be used as an intermediate or raw material for nonionic surfactants. Diethanolamine monoisopropanolamine's molecular structure contains hydrophilic amine and hydroxyl groups and hydrophobic isopropyl groups, giving it emulsifying, dispersing, wetting, and solubilizing properties. It is relatively mild, with low skin and eye irritation, and can be used as a foaming agent, foam stabilizer, thickener, and viscosity modifier in the formulation of personal care products such as shampoos, shower gels, facial cleansers, and shaving creams. Diethanolamine monoisopropanolamine can also be added to metalworking fluids such as cutting fluids, grinding fluids, and rust inhibitors as a corrosion inhibitor and pH adjuster / alkaline reserve agent, providing an alkaline environment to prevent corrosion of metals, especially ferrous metals, and neutralizing acidic substances generated during processing, maintaining system stability. The isopropyl structure of diethanolamine monoisopropanolamine may contribute to better lubricity or compatibility with the oil phase. Compared to single ethanolamines or isopropanolamines, its performance is more balanced or has a synergistic effect, and its biological stability is also relatively good. The structural characteristics of diethanol monoisopropanolamine may give it a high acid gas absorption capacity, a fast absorption rate, or a low degradation rate. In processes such as natural gas purification, refinery gas treatment, and syngas purification, it can be used as an absorbent component for removing acid gases such as H2S and CO2, and as a component of desulfurization and decarbonization solutions using the alcohol amine method.

[0003] In summary, diethanol monoisopropanolamine, with its unique molecular structure and comprehensive properties (alkalinity, complexing properties, surface activity, corrosion inhibition, reactivity, relative mildness and environmental friendliness), has found wide application in many important industrial fields such as cement industry, surfactants, metal processing, and water treatment, especially in cement grinding aid and reinforcement.

[0004] The traditional liquid alkali (NaOH / KOH) catalysis for the synthesis of DEIPA from diethanolamine (DEA) and propylene oxide (PO) has the following drawbacks: (1) the catalyst is difficult to separate and needs to be washed with water, resulting in wastewater pollution; (2) strong alkalinity corrodes the reaction equipment; (3) there are many side reactions, such as the hydrolysis of PO to generate propylene glycol. Summary of the Invention

[0005] The purpose of this invention is to address the problems of difficult catalyst separation, equipment corrosion, and waste liquid generation in the synthesis of diethanol monoisopropanolamine from diethanolamine and propylene oxide using traditional liquid base catalysts. This invention designs a highly active and selective solid base and uses this solid base as a catalyst to catalyze the ring-opening addition reaction of diethanolamine and propylene oxide to prepare diethanol monoisopropanolamine.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] A method for synthesizing diethanol monoisopropanolamine using a solid base catalyst includes: using diethanolamine and propylene oxide as raw materials, and using a solid base as a catalyst to catalyze a ring-opening addition reaction between diethanolamine and propylene oxide to synthesize diethanol monoisopropanolamine; wherein the solid base is prepared from liquid A and liquid B using a co-precipitation reaction to obtain a hydrotalcite (HT) precursor, and the hydrotalcite precursor is then calcined to obtain a Mg-Al-O composite oxide; wherein liquid A is Mg 2+ And Al 3+ The mixed aqueous solution, wherein liquid B is a mixed aqueous solution of NaOH and Na2CO3.

[0008] To further improve the activity of the solid base catalyst and avoid insufficient basic active material, the Mg... 2+ And Al 3+ The molar ratio (i.e., Mg / Al molar ratio) is 2.5:1 to 4:1.

[0009] The Mg 2+ It is provided by Mg(NO3)2 or Mg(NO3)2·6H2O; the Al 3+ It is provided by Al(NO3)3 or Al(NO3)3·9H2O.

[0010] To further improve the crystallinity of the solid base catalyst and enhance its catalytic activity, the pH value during catalyst preparation was controlled to be between 9.5 and 10.5. The molar ratio of NaOH to Na₂CO₃ was 3:1 to 4.5:1.

[0011] Specifically, the solid alkali is prepared by the following method, including the following steps:

[0012] Step (1), Solution preparation: Solution A is prepared using deionized water. Solution A contains Mg 2+The concentration is 0.6–1 mol / L; Na2CO3 and NaOH are dissolved in deionized water to prepare solution B, in which the concentration of NaOH is 0.75–1.125 mol / L;

[0013] Step (2), coprecipitation reaction: Add solution A and solution B dropwise to the reaction apparatus simultaneously and carry out the coprecipitation reaction under stirring. During the dropwise addition, control the reaction temperature at 50-70℃, the stirring speed at 500-700 rpm, and maintain the pH value of the system at 9.5-10.5. After the dropwise addition is completed, age the system at 50-70℃ for 2-4 hours.

[0014] Step (3), washing and drying: filter, wash the solid with deionized water until the conductivity of the filtrate is <50μS / cm; dry at 100-120℃ for 9-12 hours to obtain the hydrotalcite (HT) precursor;

[0015] Step (4): Place the hydrotalcite precursor in a muffle furnace and heat it from room temperature to 420-550°C at a heating rate of 3-5°C / min. Calcinate it at 420-550°C for 4-8 hours to obtain modified hydrotalcite, which is a solid alkali.

[0016] To further improve the conversion rate of DEA and the selectivity of DEIPA, the amount of solid alkali used is 1-5% wt of the mass of DEA.

[0017] To further improve the conversion rate of DEA and the selectivity of DEIPA, the molar ratio of DEA to PO is 1:1 to 1:1.1.

[0018] The ring-opening addition reaction is carried out at a temperature of 70–120°C, preferably 90–120°C, at a pressure of 0.4–0.5 MPa, and for a time of 1–3 hours.

[0019] Specifically, a method for the solid-base catalytic synthesis of diethanol monoisopropanolamine includes: adding diethanolamine and the solid base into a reaction apparatus under nitrogen protection, and heating to 40–50°C with stirring; using nitrogen gas to dropwise add propylene oxide into the reaction apparatus under positive pressure, controlling the dropping rate of PO to be 0.5–2 mL / min; after the addition is complete, controlling the temperature at 70–120°C and the pressure at 0.4–0.5 MPa to carry out a ring-opening addition reaction for 1–3 h; after the reaction is completed, cooling to 60°C and removing unreacted propylene oxide under vacuum; recovering the solid base by filtration; and distilling the crude product under reduced pressure to obtain diethanol monoisopropanolamine.

[0020] Preferably, after the reaction is complete, the mixture is cooled to 60°C and subjected to vacuum at -0.085 to -0.09 MPa to remove unreacted propylene oxide.

[0021] Preferably, the crude product is subjected to vacuum distillation at -0.0985 MPa, and the fraction collected at 135–139 °C is diethanol monoisopropanolamine.

[0022] The beneficial effects of this invention are:

[0023] (1) High reaction selectivity: The solid base has uniform alkaline sites on its surface. Using the solid base to catalyze the synthesis of diethanolamine and propylene oxide into diethanol monoisopropanolamine can improve the reaction activity and DEIPA selectivity, significantly inhibit the disubstituted byproducts (<2%), the conversion rate of DEA is greater than ≥98%, the selectivity of DEIPA is ≥97%, and the yield of DEIPA is ≥95%.

[0024] (2) Easy to separate: The catalyst can be recovered by simple filtration after the reaction, without the need for neutralization and washing; the filtrate is distilled under reduced pressure to obtain DEIPA, and the purity of DEIPA is ≥99%;

[0025] (3) Green: No wastewater discharge, low equipment corrosion; significantly reduces production costs and environmental pressure;

[0026] (4) Economic efficiency: The catalyst can be reused and its catalytic performance is stable. Even after 5 reuses, the DEIPA yield is still ≥95%. Detailed Implementation

[0027] The technical solution of the present invention will be described in detail below through specific embodiments, but the scope of protection of the present invention is not limited to the embodiments described. The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values; these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0028] Mg(NO3)2·6H2O (Nanjing Chemical Reagent Co., Ltd., analytical grade).

[0029] Al(NO3)3·9H2O (Nanjing Chemical Reagent Co., Ltd., analytical grade).

[0030] Deionized water (homemade).

[0031] Na2CO3 (Nanjing Chemical Reagent Co., Ltd., analytical grade).

[0032] NaOH (Nanjing Chemical Reagent Co., Ltd., analytical grade).

[0033] Nitrogen (Nanjing Ruier Special Gases Co., Ltd., purity 99.999%).

[0034] High-pressure reactor (Weihai Chemical Machinery Plant, 500mL capacity).

[0035] Propylene oxide (Shandong Binhua Co., Ltd., industrial grade).

[0036] Diethanolamine (Nanjing Hongbaoli Co., Ltd., industrial grade).

[0037] Muffle furnace (Derek Heat Resistant Shanghai Electric Furnace Co., Ltd.)

[0038] Conductivity meter (Tianyan Instruments Co., Ltd.)

[0039] Product testing:

[0040] The determination was performed using an Agilent 6890A gas chromatograph with an Agilent DB-1701 column (30m × 0.32mm × 0.25μm), product serial number 123-0732.

[0041] Carrier gas: He, constant flow mode, flow rate: 1.5 mL / min;

[0042] Inlet: Split mode, temperature 270℃, split ratio 20:1, injection volume 1.0μL;

[0043] Liner: Glass wool liner with a cleaned-up section;

[0044] Column temperature program: 80℃ (hold for 2 min) → 15℃ / min → 250℃ (hold for 10 min);

[0045] Detector: FID, temperature 280℃, He: 40mL / min, Air: 400mL / min, Makeup (N2): 30mL / min;

[0046] Sample pretreatment: Dissolve and dilute with anhydrous methanol to 5 mg / mL, and filter through a 0.45 μm organic filter membrane.

[0047] Conversion rate of diethanolamine (X) 二乙醇胺 The formula for calculating ) is:

[0048]

[0049] The selectivity of diethanol monoisopropanolamine (S 二乙醇单异丙醇胺 The formula for calculating ) is:

[0050]

[0051] C 二乙醇胺 : The amount of diethanolamine in the product, %;

[0052] C 二乙醇单异丙醇胺 : The amount of diethanol monoisopropanolamine in the product, %;

[0053] C 重组分 : Recombinant content in the product analyzed by gas chromatography, %;

[0054] 105: Molecular weight of diethanolamine, g / mol;

[0055] 163: Molecular weight of diethanol monoisopropanolamine, g / mol;

[0056] 221: Molecular weight of the recombinant component, g / mol;

[0057] Yield of diethanol monoisopropanolamine (Y) 二乙醇单异丙醇胺 ) Calculation formula

[0058] Y 二乙醇单异丙醇胺 =X 二乙醇胺 ×S 二乙醇单异丙醇胺

[0059] Example 1

[0060] Preparation of catalyst S-1:

[0061] (1) Solution preparation: Weigh 38.46g of Mg(NO3)2·6H2O and 18.76g of Al(NO3)3·9H2O according to the Mg / Al molar ratio of 3:1. Dissolve the two metal salts in 200mL of deionized water to prepare solution A; dissolve 5.3g of Na2CO3 and 8.0g of NaOH in 200mL of deionized water to prepare solution B.

[0062] (2) Coprecipitation reaction: Add solution A and solution B dropwise to a 500mL four-necked flask simultaneously. During the dropwise addition, control the reaction temperature at 55℃ and the stirring speed at 600rpm. Adjust and maintain the pH value of the system at 10 by controlling the dropwise acceleration rate of solution B. After the dropwise addition is completed, age at 55℃ for 3 hours.

[0063] (3) Washing and drying: Filter by suction, wash the solid with deionized water until the conductivity of the filtrate is <50μS / cm; put it in an oven and dry at 115℃ for 10 hours to obtain hydrotalcite (HT) precursor;

[0064] (4) Place the hydrotalcite precursor in a muffle furnace and heat it from room temperature to 500°C at a heating rate of 4°C / min. Calcine it at 500°C for 6 hours to obtain catalyst S-1. Crush the catalyst to 20-40 mesh and set it aside.

[0065] The high-pressure reactor was purged with nitrogen 2-3 times. Under nitrogen protection, 210g of diethanolamine and 4.2g of catalyst S-1 were added to the reactor at a DEA:PO ​​molar ratio of 1:1.05. The temperature was raised to 50℃ with stirring (500rpm). The propylene oxide storage tank was pressurized with nitrogen, and 121.8g of PO was slowly added dropwise at a rate of 0.8mL / min. After the addition was complete, the reaction temperature was controlled at 90℃ and the reaction pressure at 0.4MPa, and the reaction was maintained at this temperature for 2 hours. After the reaction, the condenser was turned on to cool the reactor to 60℃, and a vacuum was applied at -0.085MPa to remove unreacted PO. The reactor was opened, and catalyst S-1 was recovered by filtration. The crude product obtained by filtration was subjected to vacuum distillation (-0.0985MPa), and the fraction collected at 135-139℃ was identified as diethanolamine monoisopropanolamine. Chromatographic analysis showed X... 二乙醇胺 It is 98.88%, S 二乙醇单异丙醇胺 It is 97.99%, Y 二乙醇单异丙醇胺 The purity was 96.89%, and after purification, it reached 99.47%.

[0066] Under the same reaction conditions, catalyst S-1 was used 5 times. 二乙醇单异丙醇胺 It is 95.88%.

[0067] Example 2

[0068] Preparation of catalyst S-2:

[0069] (1) Solution preparation: Weigh 43.06g of Mg(NO3)2·6H2O and 18g of Al(NO3)3·9H2O according to the Mg / Al molar ratio of 3.5:1, dissolve the two metal salts in 200mL of deionized water to prepare solution A; dissolve 5.3g of Na2CO3 and 7.0g of NaOH in 200mL of deionized water to prepare solution B;

[0070] (2) Coprecipitation reaction: Add solution A and solution B dropwise to a 500mL four-necked flask simultaneously. During the dropwise addition, control the reaction temperature at 65℃ and the stirring speed at 650rpm. Adjust and maintain the pH value of the system at 9.5 by controlling the dropwise acceleration rate of solution B. After the dropwise addition is completed, age at 65℃ for 4 hours.

[0071] (3) Washing and drying: Filter by suction, wash the solid with deionized water until the conductivity of the filtrate is <50μS / cm; put it in an oven at 120℃ for 12 hours to obtain the hydrotalcite precursor.

[0072] (4) The hydrotalcite precursor was placed in a muffle furnace and heated from room temperature to 450°C at a heating rate of 3.5°C / min. It was then calcined at 450°C for 7 hours to obtain catalyst S-2. The catalyst was crushed to 20-40 mesh and set aside for later use.

[0073] The high-pressure reactor was purged with nitrogen 2-3 times. Under nitrogen protection, 210g of diethanolamine and 6.3g of catalyst S-2 were added to the reactor at a DEA:PO ​​molar ratio of 1:1.1. The temperature was raised to 50℃ with stirring (500rpm). The propylene oxide storage tank was pressurized with nitrogen, and 127.6g of PO was slowly added dropwise at a rate of 0.5mL / min. After the addition was complete, the reaction temperature was controlled at 100℃ and the reaction pressure at 0.5MPa, and the reaction was maintained at this temperature for 3 hours. After the reaction, the condenser was turned on to cool the reactor to 60℃. A vacuum was established at -0.085MPa to remove unreacted PO. The reactor was opened, and catalyst S-2 was recovered by filtration. The crude product obtained by filtration was subjected to vacuum distillation (-0.0985MPa), and the fraction collected at 135-139℃ was identified as diethanolamine monoisopropanolamine. Chromatographic analysis showed X... 二乙醇胺 It is 99.88%, S 二乙醇单异丙醇胺 It is 97.19%, Y 二乙醇单异丙醇胺 The initial purity was 97.07%, and after purification, the purity was 99.56%.

[0074] Under the same reaction conditions, catalyst S-2 was used 5 times. 二乙醇单异丙醇胺 It is 96.08%.

[0075] Example 3

[0076] Preparation of catalyst S-3:

[0077] (1) Solution preparation: Weigh 49.21g of Mg(NO3)2·6H2O and 18g of Al(NO3)3·9H2O according to the Mg / Al molar ratio of 4:1. Dissolve the two metal salts in 200mL of deionized water to prepare solution A; dissolve 5.3g of Na2CO3 and 9.0g of NaOH in 200mL of deionized water to prepare solution B.

[0078] (2) Coprecipitation reaction: Add solution A and solution B dropwise to a 500mL four-necked flask simultaneously. During the dropwise addition, control the reaction temperature at 65℃ and the stirring speed at 650rpm. Control the dropwise acceleration rate of solution B and adjust and maintain the pH value of the system at 10.5. After the dropwise addition is completed, age at 65℃ for 4 hours.

[0079] (3) Washing and drying: Filter by suction, wash the solid with deionized water until the conductivity of the filtrate is <50μS / cm; put it in an oven at 115℃ for 12 hours to obtain the hydrotalcite precursor;

[0080] (4) Place the hydrotalcite precursor in a muffle furnace and heat it from room temperature to 420°C at a heating rate of 3°C / min. Calcine it at 420°C for 6 hours to obtain catalyst S-3. Crush the catalyst to 20-40 mesh and set it aside.

[0081] The high-pressure reactor was purged with nitrogen 2-3 times. Under nitrogen protection, 210g of diethanolamine and 8.4g of catalyst S-3 were added to the reactor at a DEA:PO ​​molar ratio of 1:1.02. The temperature was raised to 50℃ with stirring (400 rpm). The propylene oxide storage tank was pressurized with nitrogen, and 118.32g of PO was slowly added dropwise at a rate of 1.5mL / min. After the addition was complete, the reaction temperature was controlled at 95℃ and the reaction pressure at 0.5MPa, and the reaction was maintained at this temperature for 2.5h. After the reaction, the condenser was turned on to cool the reactor to 60℃, and a vacuum was applied at -0.085MPa to remove unreacted PO. The reactor was opened, and catalyst S-3 was recovered by filtration. The crude product obtained by filtration was subjected to vacuum distillation (-0.0985MPa), and the fraction collected at 135-139℃ was diethanolamine monoisopropanolamine. Chromatographic analysis showed X... 二乙醇胺 It is 99.94%, S 二乙醇单异丙醇胺 It is 97.02%, Y 二乙醇单异丙醇胺 The initial purity was 96.96%, and after purification, the purity was 99.55%.

[0082] Under the same reaction conditions, catalyst S-3 was used 5 times. 二乙醇单异丙醇胺 It is 95.89%.

[0083] Example 4

[0084] Preparation of catalyst S-4:

[0085] (1) Solution preparation: Weigh 30.75g of Mg(NO3)2·6H2O and 18g of Al(NO3)3·9H2O according to the Mg / Al molar ratio of 2.5:1, dissolve the two metal salts in 200mL of deionized water to prepare solution A; dissolve 5.3g of Na2CO3 and 6.0g of NaOH in 200mL of deionized water to prepare solution B;

[0086] (2) Coprecipitation reaction: Add solution A and solution B dropwise to a 500mL four-necked flask simultaneously. During the dropwise addition, control the reaction temperature at 68℃ and the stirring speed at 650rpm. Adjust and maintain the pH value of the system at 9.5 by controlling the dropwise acceleration rate of solution B. After the dropwise addition is completed, age at 68℃ for 4 hours.

[0087] (3) Washing and drying: Filter by suction, wash the solid with deionized water until the conductivity of the filtrate is <50μS / cm; put it in an oven at 120℃ for 12 hours to obtain the hydrotalcite precursor.

[0088] (4) Place the hydrotalcite precursor in a muffle furnace and heat it from room temperature to 500°C at a heating rate of 5°C / min. Calcine it at 500°C for 6 hours to obtain catalyst S-4. Crush the catalyst to 20-40 mesh and set it aside.

[0089] The high-pressure reactor was purged with nitrogen 2-3 times. Under nitrogen protection, 210 g of diethanolamine and 9.45 g of catalyst S-4 were added to the reactor at a DEA:PO ​​molar ratio of 1:1.02. The temperature was raised to 50°C with stirring (400 rpm). The propylene oxide storage tank was pressurized with nitrogen, and 118.32 g of PO was slowly added dropwise at a rate of 1.5 mL / min. After the addition was complete, the reaction temperature was controlled at 115°C and the reaction pressure at 0.5 MPa, and the reaction was maintained at this temperature for 3 hours. After the reaction, the condenser was turned on to cool the reactor to 60°C. A vacuum was then applied at -0.085 MPa to remove unreacted PO. The reactor was opened, and catalyst S-4 was recovered by filtration. The crude product obtained by filtration was subjected to vacuum distillation (-0.0985 MPa), and the fraction collected at 135-139°C was identified as diethanolamine monoisopropanolamine. Chromatographic analysis showed X... 二乙醇胺 It is 98.01%, S 二乙醇单异丙醇胺 It is 97.88%, Y 二乙醇单异丙醇胺 The initial purity was 95.93%, and after purification, the purity was 99.88%.

[0090] Under the same reaction conditions, catalyst S-4 was used 5 times. 二乙醇单异丙醇胺 It is 95.08%.

[0091] Example 5

[0092] Preparation of catalyst S-5:

[0093] (1) Solution preparation: Weigh 43.06g of Mg(NO3)2·6H2O and 18g of Al(NO3)3·9H2O according to the Mg / Al molar ratio of 3.5:1, dissolve the two metal salts in 200mL of deionized water to prepare solution A; dissolve 5.3g of Na2CO3 and 9.0g of NaOH in 200mL of deionized water to prepare solution B;

[0094] (2) Coprecipitation reaction: Add solution A and solution B dropwise to a 500mL four-necked flask simultaneously. During the dropwise addition, control the reaction temperature at 70℃ and the stirring speed at 700rpm. Adjust and maintain the pH value of the system at 10.5 by controlling the dropwise acceleration rate of solution B. After the dropwise addition is completed, age at 70℃ for 4 hours.

[0095] (3) Washing and drying: Filter by suction, wash the solid with deionized water until the conductivity of the filtrate is <50μS / cm; put it in an oven at 120℃ for 12 hours to obtain the hydrotalcite precursor.

[0096] (4) Place the hydrotalcite precursor in a muffle furnace and heat it from room temperature to 550°C at a heating rate of 3°C / min. Calcinate it at 550°C for 8 hours to obtain catalyst S-5. Crush the catalyst to 20-40 mesh and set aside.

[0097] The high-pressure reactor was purged with nitrogen 2-3 times. Under nitrogen protection, 210g of diethanolamine and 8.4g of catalyst S-5 were added to the reactor at a DEA:PO ​​molar ratio of 1:1.08. The temperature was raised to 50℃ with stirring (600 rpm). The propylene oxide storage tank was pressurized with nitrogen, and 125.28g of PO was slowly added dropwise at a rate of 1.5mL / min. After the addition was complete, the reaction temperature was controlled at 105℃ and the reaction pressure at 0.5MPa, and the reaction was maintained at this temperature for 3 hours. After the reaction, the condenser was turned on to cool the reactor to 60℃. A vacuum was established at -0.085MPa to remove unreacted PO. The reactor was opened, and catalyst S-5 was recovered by filtration. The crude product obtained by filtration was subjected to vacuum distillation (-0.0985MPa), and the fraction collected at 135-139℃ was identified as diethanolamine monoisopropanolamine. Chromatographic analysis showed X... 二乙醇胺 It is 98.48%, S 二乙醇单异丙醇胺 It is 98.02%, Y 二乙醇单异丙醇胺 The initial purity was 96.53%, and after purification, the purity was 99.55%.

[0098] Under the same reaction conditions, catalyst S-5 was used 5 times. 二乙醇单异丙醇胺 It is 96.66%.

[0099] Example 6

[0100] Preparation of catalyst S-6:

[0101] (1) Solution preparation: Weigh 49.21g of Mg(NO3)2·6H2O and 18g of AlAl(NO3)3·9H2O according to the Mg / Al molar ratio of 4:1. Dissolve the two metal salts in 200mL of deionized water to prepare solution A; dissolve 5.3g of Na2CO3 and 6.0g of NaOH in 200mL of deionized water to prepare solution B.

[0102] (2) Coprecipitation reaction: Add solution A and solution B dropwise to a 500mL four-necked flask simultaneously. During the dropwise addition, control the reaction temperature at 65℃ and the stirring speed at 650rpm. Adjust and maintain the pH value of the system at 9.5 by controlling the dropwise acceleration rate of solution B. After the dropwise addition is completed, age at 65℃ for 3.5 hours.

[0103] (3) Washing and drying: Filter by suction, wash the solid with deionized water until the conductivity of the filtrate is <50μS / cm; put it in an oven at 120℃ for 10 hours to obtain the hydrotalcite precursor;

[0104] (4) Place the hydrotalcite precursor in a muffle furnace and heat it from room temperature to 500°C at a heating rate of 5°C / min. Calcine it at 500°C for 5 hours to obtain catalyst S-6. Crush the catalyst to 20-40 mesh and set it aside.

[0105] The high-pressure reactor was purged with nitrogen 2-3 times. Under nitrogen protection, 210g of diethanolamine and 10.5g of catalyst S-6 were added to the reactor at a DEA:PO ​​molar ratio of 1:1.05. The temperature was raised to 50°C with stirring (400 rpm). The propylene oxide storage tank was pressurized with nitrogen, and 121.8g of PO was slowly added dropwise at a rate of 0.5mL / min. After the addition was complete, the reaction temperature was controlled at 120°C and the reaction pressure at 0.5MPa, and the reaction was maintained at this temperature for 3 hours. After the reaction, the condenser was turned on to cool the reactor to 60°C. A vacuum was established at -0.085MPa to remove unreacted PO. The reactor was opened, and catalyst S-6 was recovered by filtration. The crude product obtained by filtration was subjected to vacuum distillation (-0.0985MPa), and the fraction collected at 135-139°C was identified as diethanolamine monoisopropanolamine. Chromatographic analysis showed X... 二乙醇胺 It is 99.04%, S 二乙醇单异丙醇胺 It is 97.99%, Y 二乙醇单异丙醇胺 The initial purity was 97.04%, and after purification, the purity was 99.59%.

[0106] Under the same reaction conditions, catalyst S-6 was used 5 times. 二乙醇单异丙醇胺 It is 96.56%.

[0107] Comparative Example 1

[0108] Weigh 24.605g of Mg(NO3)2·6H2O and 18g of AlAl(NO3)3·9H2O according to a Mg / Al molar ratio of 2:1. Dissolve the two metal salts in 200mL of deionized water to prepare solution A. Use solution A instead of solution A in Example 6. Other treatment conditions are the same as in Example 6. 二乙醇胺 It is 90.01%, S 二乙醇单异丙醇胺 It is 96.22%, Y 二乙醇单异丙醇胺 It is 86.60%.

[0109] Comparative Example 2

[0110] Weigh out 55.36g of Mg(NO3)2·6H2O and 18g of Al(NO3)3·9H2O according to a Mg / Al molar ratio of 4.5:1. Dissolve the two metal salts in 200mL of deionized water to prepare solution A. Use solution A instead of solution A in Example 1. Other treatment conditions are the same as in Example 1. 二乙醇胺 It was 86.33%, S 二乙醇单异丙醇胺 It is 90.42%, Y 二乙醇单异丙醇胺 It is 78.05%.

[0111] Comparative Example 3

[0112] The preparation of solutions A and B is the same as in Example 5. Solutions A and B are added dropwise to a 500mL four-necked flask simultaneously. During the dropwise addition, the reaction temperature is controlled at 70°C and the stirring speed is 700rpm. The pH value of the system is adjusted and maintained at 11 by controlling the dropwise acceleration rate of solution B. After the dropwise addition is completed, the system is aged at 70°C for 4 hours. Other treatment conditions for the preparation of the catalyst are the same as in Example 5.

[0113] The catalyst obtained was used to replace catalyst S-5 in Example 5, and all other conditions were the same as those in Example 5 for the preparation of diethanol monoisopropanolamine. 二乙醇胺 It is 90.18%, S 二乙醇单异丙醇胺 It is 92.33%, Y 二乙醇单异丙醇胺 It is 83.26%.

[0114] Comparative Example 4

[0115] The preparation of solutions A and B is the same as in Example 3. Solutions A and B are simultaneously added dropwise to a 500 mL four-necked flask. During the addition, the reaction temperature is controlled at 65°C and the stirring speed at 650 rpm. The pH of the system is maintained at 9 by controlling the drop rate of solution B. After the addition is complete, the mixture is aged at 65°C for 4 hours. Other treatment conditions for catalyst preparation are the same as in Example 3. 二乙醇胺 It was 82.19%, S 二乙醇单异丙醇胺 It is 90.33%, Y 二乙醇单异丙醇胺 It is 74.24%.

[0116] Comparative Example 5

[0117] The hydrotalcite (HT) precursor obtained in Example 1 was placed in a muffle furnace and heated from room temperature to 400°C at a heating rate of 4°C / min. It was then calcined at 400°C for 6 hours, with other treatment conditions being the same as in Example 1.

[0118] The catalyst obtained was used to replace catalyst S-1 in Example 1, and all other conditions were the same as those in Example 1 for the preparation of diethanol monoisopropanolamine. 二乙醇胺 It is 92.37%, S 二乙醇单异丙醇胺 It is 95.13%, Y 二乙醇单异丙醇胺 It is 87.87%.

[0119] Comparative Example 6

[0120] The hydrotalcite (HT) precursor obtained in Example 1 was placed in a muffle furnace and heated from room temperature to 600°C at a heating rate of 4°C / min. It was then calcined at 600°C for 6 hours, with other treatment conditions consistent with Example 1. 二乙醇胺 It was 88.07%, S 二乙醇单异丙醇胺 It is 92.19%, Y 二乙醇单异丙醇胺 It is 81.19%.

[0121] Comparative Example 7

[0122] The high-pressure reactor was purged with nitrogen 2-3 times. Under nitrogen protection, 210g of diethanolamine and 1.05g of solid NaOH (catalyst) were added to the reactor at a DEA:PO ​​molar ratio of 1:1.05. The mixture was stirred at 400rpm and heated to 50℃. The propylene oxide storage tank was pressurized with nitrogen, and 121.8g of PO was slowly added dropwise at a rate of 0.5mL / min. After the addition was complete, the reaction temperature was maintained at 120℃ and the reaction pressure at 0.5MPa for 3 hours. The reactor temperature was cooled to 60℃ by turning on the cooling water, and a vacuum was applied at -0.085MPa to remove unreacted PO. The mixture was neutralized with phosphoric acid, washed with water, filtered, dehydrated by vacuum distillation, and then distilled again to obtain diethanolamine monoisopropanolamine. Chromatographic analysis showed that X... 二乙醇胺 It is 95.22%, S 二乙醇单异丙醇胺 It is 93.15%, Y 二乙醇单异丙醇胺 The purity was 88.69%, and after purification, it reached 99.16%.

[0123] As can be seen from Examples 1-6 and Comparative Examples 1-7, the solid alkali of the present invention has uniform alkaline sites on its surface, which can suppress disubstituted byproducts (<2%); it is easy to separate, and the catalyst can be recovered by simple filtration after the reaction without the need for neutralization and washing; it is green: there is no wastewater discharge and the equipment is less corrosive; it is economical, and the DEIPA yield is still ≥95% even after the catalyst is reused 5 times.

[0124] As described above, although the invention has been shown and described with reference to specific preferred embodiments, it should not be construed as limiting the invention itself. Various changes in form and detail may be made without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A method for synthesizing diethanol monoisopropanolamine via solid base catalysis, characterized in that: include: Diethanolamine and propylene oxide were used as raw materials, and a solid base was used as a catalyst to catalyze a ring-opening addition reaction between diethanolamine and propylene oxide to synthesize diethanolamine monoisopropanolamine. The solid base was prepared from liquid A and liquid B via a co-precipitation reaction to obtain a hydrotalcite precursor, which was then calcined to obtain a Mg-Al-O composite oxide. Liquid A was Mg... 2+ And Al 3+ The mixed aqueous solution, wherein liquid B is a mixed aqueous solution of NaOH and Na2CO3.

2. The method for synthesizing diethanol monoisopropanolamine by solid base catalysis according to claim 1, characterized in that: The Mg 2+ And Al 3+ The molar ratio is 2.5:1 to 4:1; the Mg 2+ It is provided by Mg(NO3)2 or Mg(NO3)2·6H2O; the Al 3+ It is provided by Al(NO3)3 or Al(NO3)3·9H2O.

3. The method for synthesizing diethanol monoisopropanolamine catalyzed by a solid base according to claim 1, characterized in that: The molar ratio of NaOH to Na2CO3 is 3:1 to 4.5:

1.

4. The method for synthesizing diethanol monoisopropanolamine by solid base catalysis according to claim 1, characterized in that: The solid alkali is prepared by the following method, including the following steps: Step (1), Solution preparation: Prepare solution A using deionized water; dissolve Na2CO3 and NaOH in deionized water to prepare solution B; Step (2), coprecipitation reaction: Add solution A and solution B dropwise to the reaction apparatus simultaneously and carry out the coprecipitation reaction under stirring. During the dropwise addition, control the reaction temperature at 50-70℃, the stirring speed at 500-700 rpm, and maintain the pH value of the system at 9.5-10.

5. After the dropwise addition is completed, age the system at 50-70℃ for 2-4 hours. Step (3), washing and drying: filter, wash the solid with deionized water until the conductivity of the filtrate is <50μS / cm; dry at 100-120℃ for 9-12 hours to obtain the hydrotalcite precursor; Step (4): Place the hydrotalcite precursor in a muffle furnace and heat it from room temperature to 420-550°C at a heating rate of 3-5°C / min. Calcinate it at 420-550°C for 4-8 hours to obtain modified hydrotalcite, which is a solid alkali.

5. The method for synthesizing diethanol monoisopropanolamine by solid base catalysis according to claim 4, characterized in that: Mg in solution A 2+ The concentration of NaOH in solution B is 0.6–1 mol / L; the concentration of NaOH in solution B is 0.75–1.125 mol / L.

6. The method for synthesizing diethanol monoisopropanolamine catalyzed by a solid base according to claim 1, characterized in that: The amount of the solid alkali used is 1-5% wt of the mass of diethanolamine.

7. The method for synthesizing diethanol monoisopropanolamine catalyzed by a solid base according to claim 1, characterized in that: The molar ratio of diethanolamine to propylene oxide is 1:1 to 1:1.

1.

8. The method for synthesizing diethanol monoisopropanolamine catalyzed by a solid base according to claim 1, characterized in that: The ring-opening addition reaction is carried out at a temperature of 70–120°C, a pressure of 0.4–0.5 MPa, and a time of 1–3 hours.

9. The method for synthesizing diethanol monoisopropanolamine catalyzed by a solid base according to claim 1, characterized in that: include: Under nitrogen protection, diethanolamine and solid alkali are added to the reaction apparatus, and the temperature is raised to 40-50°C with stirring. Propylene oxide was added dropwise into the reaction apparatus using nitrogen gas under positive pressure. The dropping rate of propylene oxide was controlled at 0.5–2 mL / min. After the addition was complete, the temperature was controlled at 70–120 °C and the pressure at 0.4–0.5 MPa to carry out the ring-opening addition reaction for 1–3 h. After the reaction was completed, the mixture was cooled to 60 °C and unreacted propylene oxide was removed under vacuum. The solid alkali was recovered by filtration. The crude product was then subjected to vacuum distillation to obtain diethanol monoisopropanolamine.

10. The method for synthesizing diethanol monoisopropanolamine catalyzed by a solid base according to claim 9, characterized in that: After the reaction is complete, the mixture is cooled to 60°C and subjected to vacuum at -0.085 to -0.09 MPa to remove unreacted propylene oxide. The crude product is then subjected to vacuum distillation at -0.0985 MPa, and the fraction collected at 135 to 139°C is diethanol monoisopropanolamine.

Images