Synthesis method of LO < + >-grade dipropylene glycol

Abstract

The invention relates to a synthesis method of LO < + >-grade dipropylene glycol, and belongs to the technical field of LO < + >-grade dipropylene glycol synthesis, the method comprises the following steps: stirring 200g of 1, 2-propylene glycol and 100g of propylene oxide at 60-80r / min for 10-15min to obtain a pre-reaction material; 3 g of a biomass charcoal-based solid acid catalyst is added into the pre-reaction material and added into a 500 mL mechanical stirring reaction kettle, then the reaction kettle is sealed, nitrogen is introduced to remove air in the reaction kettle, the pressure of the reaction kettle reaches 0.3 MPa, heating stirring is started, the temperature is slowly increased to 120 DEG C, an emptying valve needs to be gradually opened in the temperature increasing process to release a small amount of nitrogen, and the reaction kettle is cooled to the room temperature; the pressure of the reaction kettle is kept at 0.3 MPa all the time, the dipropylene glycol is prepared through a ring-opening condensation reaction, and the LO < + >-grade dipropylene glycol is obtained after the dipropylene glycol is separated and purified. In the method, the biomass charcoal-based solid acid catalyst shows relatively high catalytic activity, so that the reaction has a relatively high conversion rate, and the catalyst can be recycled after being separated and recycled, and is simple in treatment after the reaction and environment-friendly.

Description

Technical Field

[0001] The invention belongs to the technical field of LO+ grade dipropylene glycol synthesis, and particularly relates to a method for synthesizing LO+ grade dipropylene glycol. Background Art

[0002] Dipropylene glycol (also known as dipropylene glycol, dipropylene glycol, etc., referred to as DPG in English) is an odorless, colorless, slightly viscous liquid with a spicy sweet taste at room temperature. It is water-soluble and hygroscopic, soluble in water and toluene, miscible in methanol and ether, non-corrosive, has little irritation to the skin, and has very low toxicity. In addition, dipropylene glycol has good solubility properties, so it can be used as an ideal solvent for daily chemical flavors.

[0003] However, in recent years, with the gradual improvement of consumption levels and the development of luxury goods industries such as cosmetics and perfumes, the market demand for high-quality dipropylene glycol has also been gradually increasing. However, the current domestic dipropylene glycol supply capacity is weak and is not enough to meet market demand, especially the demand for high-quality dipropylene glycol products mostly relies on imports. In addition, due to the serious overcapacity of 1,2-propylene glycol, there is a risk of sales obstruction, inventory backlog, and even shutdown. At the same time, the price of 1,2-propylene glycol has dropped, resulting in a serious decline in the profits of domestic 1,2-propylene glycol manufacturers. Summary of the invention

[0004] The object of the present invention is to provide a method for synthesizing LO+ grade dipropylene glycol in order to solve the above problems.

[0005] The present invention achieves the above-mentioned purpose through the following technical solutions:

[0006] The present invention provides a method for synthesizing LO+ grade dipropylene glycol, comprising the following steps:

[0007] (i) stirring 200 g of 1,2-propylene glycol and 100 g of propylene oxide at 60-80 r / min for 10-15 min to obtain a pre-reaction material;

[0008] (ii) Add 3g of biomass carbon-based solid acid catalyst to the pre-reaction material, add it to a 500mL mechanically stirred reactor, then seal the reactor, introduce nitrogen to remove the air in the reactor and make the reactor pressure reach 0.3MPa, start heating and stirring, slowly heat up to 120°C, and gradually open the vent valve to release a small amount of nitrogen during the heating process to ensure that the reactor pressure is always maintained at 0.3MPa, prepare dipropylene glycol through ring-opening condensation reaction, and separate and purify dipropylene glycol to obtain LO+ grade dipropylene glycol. Put the residual liquid produced by separation into a centrifuge, set the speed to 2000r / min, centrifuge for 5min, and remove the supernatant. Subsequently, add deionized water for ultrasonic washing, centrifuge to remove the supernatant, repeat three times, recover the biomass carbon-based solid acid catalyst, and reuse it after drying.

[0009] As a further optimization scheme of the present invention, the molar ratio of 1,2-propylene glycol to propylene oxide is (1-6):1; the ring-opening condensation reaction temperature is 80-150°C; the ring-opening condensation reaction pressure is 0.1-0.8MPa; the ring-opening condensation reaction time is 0.5-6h

[0010] As a further optimization scheme of the present invention, the specific steps of separating and purifying dipropylene glycol are: firstly, dipropylene glycol is distilled at atmospheric pressure for 25-30 minutes, and then secondary distilled at reduced pressure to 1.3-2.0 kPa (10-15 mmHg) for 30-40 minutes to obtain LO+ grade dipropylene glycol.

[0011] As a further optimization scheme of the present invention, the preparation process of the biomass carbon-based solid acid catalyst is:

[0012] (i) grinding the dried biomass charcoal raw material alfalfa straw into solid powder, transferring the obtained solid powder into a quartz boat, placing it in a muffle furnace and sealing it, and carbonizing it at a heating rate of 10° C. / min under the protection of inert gas to obtain an alfalfa straw charcoal material;

[0013] (ii) Take 4 g of alfalfa straw carbon material and 60 ml of sulfonating agent and add them into a round-bottom flask and stir vigorously. After the sulfonation reaction is completed, use hot deionized water to repeatedly wash the obtained solid carbon material until the pH value of the filtrate is the same as the pH value of the original deionized water. After drying in a vacuum drying oven at 80°C for 4 hours, a biomass carbon-based solid acid catalyst is obtained.

[0014] As a further optimization solution of the present invention, the inert gas is one of nitrogen, argon and helium.

[0015] As a further optimization scheme of the present invention, the carbonization temperature is 300-600° C.; the carbonization time is 1-8 hours.

[0016] As a further optimization scheme of the present invention, the sulfonation reagent is one of concentrated sulfuric acid, chlorosulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, and p-aminobenzenesulfonic acid.

[0017] As a further optimization scheme of the present invention, the sulfonation temperature is 140-180° C.; the sulfonation time is 2-10 h.

[0018] The beneficial effects of the present invention are as follows: the present invention uses 1,2-propylene glycol and propylene oxide as raw materials, and obtains a LO+ grade dipropylene glycol product under the action of a biomass carbon-based solid acid catalyst. In this method, the biomass carbon-based solid acid catalyst exhibits high catalytic activity, so that the reaction has a high conversion rate, and the catalyst can be reused after separation and recovery, and the post-reaction treatment is simple and environmentally friendly. DETAILED DESCRIPTION

[0019] The present application is described in further detail below. It is necessary to point out that the following specific implementation methods are only used to further illustrate the present application and cannot be understood as limiting the scope of protection of the present application. Technicians in this field can make some non-essential improvements and adjustments to the present application based on the above application content.

[0020] 1. Materials

[0021] Unless otherwise specified, the methods used in the present invention are conventional methods known to those skilled in the art, and the reagents and other materials used are commercially available products unless otherwise specified.

[0022] The biomass carbon-based solid acid catalyst in Comparative Example 3 adopts the biomass carbon-based solid acid catalyst prepared in Chinese invention patent: CN115254143B.

[0023] 2. Methods

[0024] Example 1

[0025] The dried biomass charcoal raw material alfalfa straw was ground into solid powder, the solid powder was transferred to a quartz boat, placed in a muffle furnace and sealed, the temperature was raised to 400°C at a heating rate of 10°C / min under nitrogen protection, and then kept warm for 4 hours for carbonization to obtain alfalfa straw charcoal material;

[0026] 4 g of alfalfa straw carbon material and 60 ml of concentrated sulfuric acid were added to a round-bottom flask, and then vigorously stirred at 180 ° C for 4 h. After the sulfonation reaction was completed, the solid carbon material was repeatedly washed with hot deionized water until the pH value of the filtrate was the same as the pH value of the original deionized water. After drying at 80 ° C in a vacuum drying oven for 4 h, a biomass carbon-based solid acid catalyst was obtained;

[0027] 200 g of 1,2-propylene glycol and 100 g of propylene oxide were stirred at 60 r / min for 10 min (the molar ratio of 1,2-propylene glycol to propylene oxide was 3:1) to obtain a pre-reaction material;

[0028] 3g of biomass carbon-based solid acid catalyst was added to the pre-reaction material, added to a 500mL mechanical stirring reactor, and then the reactor was sealed, nitrogen was introduced to remove the air in the reactor and the pressure of the reactor reached 0.3MPa, heating and stirring were turned on, and the temperature was slowly raised to 120°C. During the heating process, the vent valve was gradually opened to release a small amount of nitrogen to ensure that the pressure of the reactor was always maintained at 0.3MPa, and dipropylene glycol was prepared through a ring-opening condensation reaction (the ring-opening condensation reaction temperature was 120°C, the pressure was 0.3MPa, and the time was 2h). After the reaction was completed, dipropylene glycol was distilled at atmospheric pressure for 25min, and then secondary distilled for 30min at a reduced pressure of 1.3kPa (10mmHg) to obtain LO+ grade dipropylene glycol.

[0029] Example 2

[0030] The dried biomass charcoal raw material alfalfa straw was ground into solid powder, the solid powder was transferred to a quartz boat, placed in a muffle furnace and sealed, the temperature was raised to 300°C at a heating rate of 10°C / min under nitrogen protection, and then kept warm for 1 hour for carbonization to obtain alfalfa straw charcoal material;

[0031] 4 g of alfalfa straw carbon material and 60 ml of concentrated sulfuric acid were added to a round-bottom flask, and then vigorously stirred at 160 ° C for 6 h. After the sulfonation reaction was completed, the solid carbon material was repeatedly washed with hot deionized water until the pH value of the filtrate was the same as the pH value of the original deionized water. After drying at 80 ° C in a vacuum drying oven for 4 h, a biomass carbon-based solid acid catalyst was obtained;

[0032] 200 g of 1,2-propylene glycol and 100 g of propylene oxide were stirred at 70 r / min for 12 min (the molar ratio of 1,2-propylene glycol to propylene oxide was 3:1) to obtain a pre-reaction material;

[0033] 3g of biomass carbon-based solid acid catalyst was added to the pre-reaction material, added to a 500mL mechanical stirring reactor, and then the reactor was sealed, nitrogen was introduced to remove the air in the reactor and the pressure of the reactor reached 0.4MPa, heating and stirring were turned on, and the temperature was slowly raised to 120°C. During the heating process, the vent valve should be gradually opened to release a small amount of nitrogen to ensure that the pressure of the reactor was always maintained at 0.4MPa, and dipropylene glycol was prepared through a ring-opening condensation reaction (the ring-opening condensation reaction temperature was 120°C, the pressure was 0.4MPa, and the time was 3h). After the reaction, dipropylene glycol was distilled at atmospheric pressure for 26min, and then secondary distilled for 35min at a reduced pressure of 1.6kPa (12mmHg) to obtain LO+ grade dipropylene glycol.

[0034] Example 3

[0035] The dried biomass charcoal raw material alfalfa straw was ground into solid powder, the obtained solid powder was transferred to a quartz boat, placed in a muffle furnace and sealed, and the temperature was raised to 600°C at a heating rate of 10°C / min under nitrogen protection, and then kept warm for 8 hours for carbonization to obtain alfalfa straw charcoal material;

[0036] 4 g of alfalfa straw carbon material and 60 ml of concentrated sulfuric acid were added to a round-bottom flask, and then vigorously stirred at 140 ° C for 10 h. After the sulfonation reaction was completed, the solid carbon material was repeatedly washed with hot deionized water until the pH value of the filtrate was the same as the pH value of the original deionized water. After drying at 80 ° C in a vacuum drying oven for 4 h, a biomass carbon-based solid acid catalyst was obtained;

[0037] 200 g of 1,2-propylene glycol and 100 g of propylene oxide were stirred at 80 r / min for 15 min (the molar ratio of 1,2-propylene glycol to propylene oxide was 3:1) to obtain a pre-reaction material;

[0038] 3 g of biomass carbon-based solid acid catalyst was added to the pre-reaction material, added to a 500 mL mechanically stirred reactor, and then the reactor was sealed, nitrogen was introduced to remove the air in the reactor and the pressure of the reactor reached 0.3 MPa, heating and stirring were turned on, and the temperature was slowly raised to 110°C. During the heating process, the vent valve should be gradually opened to release a small amount of nitrogen to ensure that the pressure of the reactor was always maintained at 0.3 MPa. Dipropylene glycol was prepared through a ring-opening condensation reaction (the ring-opening condensation reaction temperature was 110°C, the pressure was 0.3 MPa, and the time was 4 h). The dipropylene glycol was distilled at atmospheric pressure for 30 min, and then secondary distilled for 40 min at a reduced pressure of 2.0 kPa (15 mmHg) to obtain LO+ grade dipropylene glycol.

[0039] Comparative Example 1

[0040] The dried biomass charcoal raw material rape straw was ground into solid powder, the solid powder was transferred to a quartz boat, placed in a muffle furnace and sealed, the temperature was raised to 400°C at a heating rate of 10°C / min under nitrogen protection, and then kept warm for 4 hours for carbonization to obtain rape straw charcoal material;

[0041] 4 g of rape straw carbon material and 60 ml of concentrated sulfuric acid were added to a round-bottom flask, and then vigorously stirred at 180 ° C for 4 h. After the sulfonation reaction was completed, the solid carbon material was repeatedly washed with hot deionized water until the pH value of the filtrate was the same as the pH value of the original deionized water. After drying at 80 ° C in a vacuum drying oven for 4 h, a biomass carbon-based solid acid catalyst was obtained;

[0042] 200 g of 1,2-propylene glycol and 100 g of propylene oxide were stirred at 60 r / min for 10 min (the molar ratio of 1,2-propylene glycol to propylene oxide was 3:1) to obtain a pre-reaction material;

[0043] 3g of biomass carbon-based solid acid catalyst was added to the pre-reaction material, added to a 500mL mechanical stirring reactor, and then the reactor was sealed, nitrogen was introduced to remove the air in the reactor and the pressure of the reactor reached 0.3MPa, heating and stirring were turned on, and the temperature was slowly raised to 120°C. During the heating process, the vent valve was gradually opened to release a small amount of nitrogen to ensure that the pressure of the reactor was always maintained at 0.3MPa, and dipropylene glycol was prepared through a ring-opening condensation reaction (the ring-opening condensation reaction temperature was 120°C, the pressure was 0.3MPa, and the time was 2h). After the reaction was completed, dipropylene glycol was distilled at atmospheric pressure for 25min, and then secondary distilled for 30min at a reduced pressure of 1.3kPa (10mmHg) to obtain LO+ grade dipropylene glycol.

[0044] Comparative Example 2

[0045] The dried biomass charcoal raw material alfalfa straw was ground into solid powder, the solid powder was transferred to a quartz boat, placed in a muffle furnace and sealed, the temperature was raised to 400°C at a heating rate of 10°C / min under nitrogen protection, and then kept warm for 4 hours for carbonization to obtain alfalfa straw charcoal material;

[0046] 4 g of alfalfa straw carbon material and 60 ml of concentrated sulfuric acid were added to a round-bottom flask, and then vigorously stirred at 180 ° C for 4 h. After the sulfonation reaction was completed, the solid carbon material was repeatedly washed with hot deionized water until the pH value of the filtrate was the same as the pH value of the original deionized water. After drying at 80 ° C in a vacuum drying oven for 4 h, a biomass carbon-based solid acid catalyst was obtained;

[0047] 200 g of 1,2-propylene glycol and 100 g of propylene oxide were stirred at 60 r / min for 10 min (the molar ratio of 1,2-propylene glycol to propylene oxide was 3:1) to obtain a pre-reaction material;

[0048] 3g of biomass carbon-based solid acid catalyst was added to the pre-reaction material, added to a 500mL mechanical stirring reactor, and then the reactor was sealed, nitrogen was introduced to remove the air in the reactor and the pressure of the reactor reached 0.3MPa, heating and stirring were turned on, and the temperature was slowly raised to 120°C. During the heating process, the vent valve should be gradually opened to release a small amount of nitrogen to ensure that the pressure of the reactor was always maintained at 0.3MPa, and dipropylene glycol was prepared through a ring-opening condensation reaction (the ring-opening condensation reaction temperature was 120°C, the pressure was 0.3MPa, and the time was 2h). After the reaction, dipropylene glycol was distilled at atmospheric pressure for 25min to obtain LO+ grade dipropylene glycol.

[0049] Comparative Example 3

[0050] 200 g of 1,2-propylene glycol and 100 g of propylene oxide were stirred at 60 r / min for 10 min (the molar ratio of 1,2-propylene glycol to propylene oxide was 3:1) to obtain a pre-reaction material;

[0051] 3g of biomass carbon-based solid acid catalyst was added to the pre-reaction material, added to a 500mL mechanical stirring reactor, and then the reactor was sealed, nitrogen was introduced to remove the air in the reactor and the pressure of the reactor reached 0.3MPa, heating and stirring were turned on, and the temperature was slowly raised to 120°C. During the heating process, the vent valve was gradually opened to release a small amount of nitrogen to ensure that the pressure of the reactor was always maintained at 0.3MPa, and dipropylene glycol was prepared through a ring-opening condensation reaction (the ring-opening condensation reaction temperature was 120°C, the pressure was 0.3MPa, and the time was 2h). After the reaction was completed, dipropylene glycol was distilled at atmospheric pressure for 25min, and then secondary distilled for 30min at a reduced pressure of 1.3kPa (10mmHg) to obtain LO+ grade dipropylene glycol.

[0052] Performance Testing

[0053] (I) The LO+ grade dipropylene glycol prepared by the methods of Examples 1-3 and Comparative Examples 1-3 was placed at -10°C for 12 hours, and a microscope was used to observe whether the LO+ grade dipropylene glycol was crystallized; the chromaticity of the dipropylene glycol was detected by platinum-cobalt colorimetry; the purity of the LO+ grade dipropylene glycol was analyzed by gas chromatography, and the test results are shown in the following table:

[0054] project Crystallization rate % Chroma purity% Example 1 0 6 99.92 Example 2 1 7 99.91 Example 3 0 7 99.76 Comparative Example 1 3 9 99.29 Comparative Example 2 8 10 99.35 Comparative Example 3 4 9 99.12

[0055] It can be seen from the above table that the LO+ grade dipropylene glycol prepared by the method of Examples 1-3 is superior to that of Comparative Examples 1-3 in terms of low-temperature crystallization rate, chromaticity and purity. In summary, the LO+ grade dipropylene glycol prepared by the method of Examples 1-3 reaches the standard grade.

[0056] (ii) The biomass carbon-based solid acid catalyst obtained by centrifugal separation in Example 1 and Comparative Example 1 was recycled and analyzed by gas chromatography. The gas chromatography results are shown in the following table:

[0057]

[0058] It can be seen from the above table that after the biomass carbon-based solid acid catalyst prepared by the method of Example 1 is recycled for 5 times, the total selectivity of dipropylene glycol and tripropylene glycol can still be maintained above 97%, and it has good recycling performance.

[0059] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A method for synthesizing LO+ grade dipropylene glycol, characterized in that: The following steps are involved: (i) stirring 200 g of 1,2-propylene glycol and 100 g of propylene oxide at 60-80 r / min for 10-15 min to obtain a pre-reaction material; (ii) Add 3g of biomass carbon-based solid acid catalyst to the pre-reaction material, add it to a 500mL mechanically stirred reactor, then seal the reactor, introduce nitrogen to remove the air in the reactor and make the reactor pressure reach 0.3MPa, start heating and stirring, slowly heat up to 120°C, and gradually open the vent valve to release a small amount of nitrogen during the heating process to ensure that the reactor pressure is always maintained at 0.3MPa, prepare dipropylene glycol through ring-opening condensation reaction, and separate and purify dipropylene glycol to obtain LO+ grade dipropylene glycol. Put the residual liquid produced by separation into a centrifuge, set the speed to 2000r / min, centrifuge for 5min, and remove the supernatant. Subsequently, add deionized water for ultrasonic washing, centrifuge to remove the supernatant, repeat three times, recover the biomass carbon-based solid acid catalyst, and reuse it after drying.

2. The method for synthesizing LO+ grade dipropylene glycol according to claim 1, characterized in that: The ring-opening condensation reaction temperature is 80-150° C.; the ring-opening condensation reaction pressure is 0.1-0.8 MPa; and the ring-opening condensation reaction time is 0.5-6 h.

3. The method for synthesizing LO+ grade dipropylene glycol according to claim 1, characterized in that: The specific steps of separating and purifying dipropylene glycol are as follows: firstly, dipropylene glycol is distilled at atmospheric pressure for 25-30 minutes, and then secondary distilled at reduced pressure to 1.3-2.0 kPa (10-15 mmHg) for 30-40 minutes to obtain LO+ grade dipropylene glycol.

4. The method for synthesizing LO+ grade dipropylene glycol according to claim 1, characterized in that: The preparation process of the biomass carbon-based solid acid catalyst is as follows: (i) grinding the dried biomass charcoal raw material alfalfa straw into solid powder, transferring the obtained solid powder into a quartz boat, placing it in a muffle furnace and sealing it, and carbonizing it at a heating rate of 10° C. / min under the protection of inert gas to obtain an alfalfa straw charcoal material; (ii) Take 4 g of alfalfa straw carbon material and 60 ml of sulfonating agent and add them into a round-bottom flask and stir vigorously. After the sulfonation reaction is completed, use hot deionized water to repeatedly wash the obtained solid carbon material until the pH value of the filtrate is the same as the pH value of the original deionized water. After drying in a vacuum drying oven at 80°C for 4 hours, a biomass carbon-based solid acid catalyst is obtained.

5. The method for synthesizing LO+ grade dipropylene glycol according to claim 4, characterized in that: The inert gas is one of nitrogen, argon and helium.

6. The method for synthesizing LO+ grade dipropylene glycol according to claim 4, characterized in that: The carbonization temperature is 300-600° C.; the carbonization time is 1-8 hours.

7. The method for synthesizing LO+ grade dipropylene glycol according to claim 4, characterized in that: The sulfonating agent is one of concentrated sulfuric acid, chlorosulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid and p-aminobenzenesulfonic acid.

8. The method for synthesizing LO+ grade dipropylene glycol according to claim 4, characterized in that: The sulfonation temperature is 140-180° C.; the sulfonation time is 2-10 hours.

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