A catalyst for preparing propylene glycol monoethyl ether acetate, a preparation method and application thereof
Nano-sized molybdenum cerium phosphate catalysts were prepared by grinding and supercritical oxygen crystallization, which solved the problems of low yield of propylene glycol monoethyl ether acetate and difficulty in catalyst reuse in the existing technology, and achieved high yield and easy separation of catalytic effects.
Patent Information
- Application Number
- CN202410272789.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-03-11
- Publication Date
- 2025-11-18
- Estimated Expiration
- 2044-03-11
AI Technical Summary
In existing technologies, propylene glycol monoethyl ether acetate has a low yield and the catalyst is difficult to reuse. Liquid acid catalysts are prone to equipment corrosion and are difficult to separate and purify.
Nanoparticles of cerium molybdenum phosphate catalyst with the molecular formula CenH3-3nPMo12O40 were prepared by grinding and supercritical oxygen crystallization. The high solubility and high diffusivity of supercritical oxygen promotes full contact of reactants, forming a catalyst with small crystals and high crystallinity, and increasing acidic active sites.
The yield of propylene glycol monoethyl ether acetate was improved, and the catalyst was easily separated from the product, which facilitated its reuse.
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Figure CN118162209B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of fine chemicals technology, specifically relating to a catalyst for preparing propylene glycol monoethyl ether acetate, its preparation method, and its application. Background Technology
[0002] Propylene glycol ether esters are a new generation of green and environmentally friendly "universal solvents" with excellent dissolving properties. Propylene glycol monoethyl ether acetate is one of the most important products in this series of solvents, widely used in coatings, pigments, electronic chemicals and other industries.
[0003] Propylene glycol monoethyl ether acetate is mainly prepared by the esterification reaction of propylene glycol monoethyl ether and acetic acid. While acid catalysts can be used for esterification, liquid acid catalysts present challenges such as equipment corrosion, environmental pollution, and difficulties in separation and purification. Therefore, research on solid acid catalysts has become a hot topic. Current research reports on the preparation of propylene glycol monoethyl ether acetate via esterification of propylene glycol monoethyl ether and acetic acid primarily use strong acid-type ion exchange resins as catalysts, resulting in low yields of propylene glycol monoethyl ether acetate, only around 75%. Using heteropoly acids as catalysts can increase the yield of propylene glycol monoethyl ether acetate to over 90%, but heteropoly acids are readily soluble in water and organic solvents, making separation and purification difficult and hindering reuse. Summary of the Invention
[0004] Objective of the invention: The technical problem to be solved by the present invention is to address the shortcomings of the prior art by providing a catalyst for the preparation of propylene glycol monoethyl ether acetate and a method for preparing the same. The catalyst is a solid acid, the yield of propylene glycol monoethyl ether acetate is high, and the catalyst is not easily soluble in water, is easy to separate from the product, and is easy to reuse.
[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:
[0006] A catalyst for the preparation of propylene glycol monoethyl ether acetate, with the molecular formula Ce. n H 3-3n PMo 12 O 40 ; where n ranges from 0.1 to 0.9.
[0007] Furthermore, the present invention improves the preparation method of the above-mentioned catalyst for preparing propylene glycol monoethyl ether acetate by comprising the following steps:
[0008] (1) Add cerium source and molybdenum phosphoric acid to a grinder and grind them together to obtain a solid-phase reaction mixture;
[0009] (2) Place the solid reaction mixture in a supercritical crystallization kettle, introduce oxygen, maintain the temperature at 25-45℃, carry out the crystallization reaction under supercritical conditions, and obtain the crystallized product.
[0010] (3) Cool the crystallized product to room temperature, then wash it with deionized water, and finally dry it to obtain the product.
[0011] Specifically, in step (1), the cerium source is any one of cerium nitrate, cerium chloride, and cerium oxalate.
[0012] Specifically, in step (1), the cerium source and molybdenum phosphoric acid are mixed at a molar ratio of 1.25 to 15:1.
[0013] Specifically, in step (1), the grinding and mixing process uses a grinding mill with a rotation speed of 600 r / min and a time of 30 to 45 min.
[0014] Specifically, in step (2), the pressure inside the supercritical crystallization vessel is 5-8 MPa, and the crystallization reaction time is 0.5-2 h.
[0015] Specifically, in step (2), the oxygen concentration introduced into the supercritical crystallization vessel is not less than 99.9%.
[0016] Specifically, in step (3), deionized water is used for washing until the pH of the filtrate is 7.0.
[0017] Specifically, in step (3), the drying temperature is 100-120°C and the time is 12-24 hours.
[0018] Furthermore, the present invention also claims protection for the use of the above-described catalyst in the preparation of propylene glycol monoethyl ether acetate.
[0019] Beneficial effects:
[0020] This invention is the first to use a grinding method combined with supercritical oxygen crystallization to prepare a cerium molybdenum phosphate catalyst. Due to the high solubility and high diffusivity of supercritical oxygen, the solid reaction mixture obtained by grinding is in full contact with oxygen in the crystallization vessel and dissolves rapidly. The crystallization time is short, which is conducive to the formation of nano-cerium molybdenum phosphate with small grain size and high crystallinity, and the yield is high. The surface of nano-cerium molybdenum phosphate has a large number of exposed acidic active sites and abundant acidity. Under the action of this catalyst, the yield of propylene glycol monoethyl ether acetate is high. Attached Figure Description
[0021] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, and the advantages of the present invention in the above and / or other aspects will become clearer.
[0022] Figure 1 These are the XRD patterns of cerium molybdenum phosphate prepared in Example 4 and the comparative example. Detailed Implementation
[0023] The present invention can be better understood from the following embodiments.
[0024] Example 1
[0025] A catalyst for preparing propylene glycol monoethyl ether acetate and a method thereof, comprising the following steps:
[0026] 2.72 g of cerium oxalate and 5.48 g of molybdenum phosphate were ground and mixed for 45 min (cerium source to molybdenum phosphate molar ratio 1.7:1, mill speed 600 r / min) to obtain a solid-phase reaction mixture. The solid-phase reaction mixture was placed in a supercritical crystallization reactor, oxygen was introduced, and the temperature was raised to 30 °C for crystallization reaction. The reactor pressure was 6 MPa, and the crystallization reaction time was 1 h, yielding a crystallized product. The crystallized product was cooled to room temperature and then washed with deionized water until the pH of the filtrate reached 7.0. Finally, it was dried at 100 °C for 24 h to obtain the cerium molybdenum phosphate catalyst. The mass percentage of each element was calculated based on the X-ray fluorescence spectrometry (XRF) analysis results, and it was determined to be Ce. 0.3 H 2.1 PMo 12 O 40 The yield was 97.5%.
[0027] Example 2
[0028] A catalyst for preparing propylene glycol monoethyl ether acetate and a method thereof, comprising the following steps:
[0029] 1.23 g of cerium chloride and 6.58 g of molybdenum phosphate were ground and mixed for 30 min (cerium source to molybdenum phosphate molar ratio 1.25:1, mill speed 600 r / min) to obtain a solid-phase reaction mixture. The solid-phase reaction mixture was placed in a supercritical crystallization reactor, oxygen was introduced, and the temperature was raised to 25 °C for crystallization reaction. The reactor pressure was 5 MPa, and the crystallization reaction time was 2 h, yielding a crystallized product. The crystallized product was cooled to room temperature and then washed with deionized water until the pH of the filtrate reached 7.0. Finally, it was dried at 110 °C for 12 h to obtain a cerium molybdenum phosphate catalyst, which was identified as Ce based on X-ray fluorescence spectroscopy (XRF) analysis. 0.1 H 2.7 PMo 12 O 40 The yield was 96.8%.
[0030] Example 3
[0031] A catalyst for preparing propylene glycol monoethyl ether acetate and a method thereof, comprising the following steps:
[0032] 4.89 g of cerium nitrate and 1.83 g of molybdenum phosphate were ground and mixed for 40 min (cerium source to molybdenum phosphate molar ratio 15:1, mill speed 600 r / min) to obtain a solid-phase reaction mixture. This mixture was placed in a supercritical crystallization reactor, oxygen was introduced, and the temperature was raised to 45 °C for crystallization. The reactor pressure was 8 MPa, and the crystallization reaction time was 0.5 h, yielding a crystallized product. The crystallized product was cooled to room temperature and then washed with deionized water until the pH of the filtrate reached 7.0. Finally, it was dried at 120 °C for 24 h to obtain a cerium molybdenum phosphate catalyst. Based on X-ray fluorescence spectroscopy (XRF) analysis, it was determined to be Ce. 0.9 H 0.3 PMo 12 O 40 The yield was 99.3%.
[0033] Example 4
[0034] A catalyst for preparing propylene glycol monoethyl ether acetate and a method thereof, comprising the following steps:
[0035] 3.26 g of cerium nitrate and 1.83 g of molybdenum phosphate were ground and mixed for 40 min (cerium source to molybdenum phosphate molar ratio 10:1, mill speed 600 r / min) to obtain a solid-phase reaction mixture. The solid-phase reaction mixture was placed in a supercritical crystallization reactor, oxygen was introduced, and the temperature was raised to 40 °C for crystallization reaction. The reactor pressure was 7 MPa, and the crystallization reaction time was 1.5 h, yielding a crystallized product. The crystallized product was cooled to room temperature and then washed with deionized water until the pH of the filtrate reached 7.0. Finally, it was dried at 120 °C for 24 h to obtain a cerium molybdenum phosphate catalyst, which was identified as Ce based on X-ray fluorescence spectroscopy (XRF) analysis. 0.7 H 0.9 PMo 12 O 40 The yield was 98.8%.
[0036] Example 5
[0037] A catalyst for preparing propylene glycol monoethyl ether acetate and a method thereof, comprising the following steps:
[0038] 8.61 g of cerium chloride and 8.77 g of molybdenum phosphate were ground and mixed for 40 min (cerium source to molybdenum phosphate molar ratio 7:1, mill speed 600 r / min) to obtain a solid-phase reaction mixture. The solid-phase reaction mixture was placed in a supercritical crystallization reactor, oxygen was introduced, and the temperature was raised to 45 °C for crystallization reaction. The reactor pressure was 8 MPa, and the crystallization reaction time was 2 h, yielding a crystallized product. The crystallized product was cooled to room temperature and then washed with deionized water until the pH of the filtrate reached 7.0. Finally, it was dried at 120 °C for 24 h to obtain a cerium molybdenum phosphate catalyst, which was identified as Ce based on X-ray fluorescence spectroscopy (XRF) analysis. 0.6 H 1.2 PMo 12 O 40 The yield was 99.0%.
[0039] Comparative Example
[0040] Following the operating conditions for preparing the cerium molybdenum phosphate catalyst in Example 4, but without supercritical oxygen: 3.26 g of cerium nitrate and 1.83 g of molybdenum phosphate were ground and mixed for 40 min (cerium source to molybdenum phosphate molar ratio 10:1, mill speed 600 r / min) to obtain a solid-phase reaction mixture. This mixture was placed in a supercritical crystallization reactor, and oxygen was continuously introduced into the reactor through a vent pipe from the bottom and discharged from the top. The pressure inside the reactor was maintained at 0.1 MPa. The temperature was raised to 40 °C for crystallization, and the crystallization time was 1.5 h. The crystallized product was cooled to room temperature and then washed with deionized water until the pH of the filtrate reached 7.0. Finally, it was dried at 120 °C for 24 h to obtain the cerium molybdenum phosphate catalyst. Based on X-ray fluorescence spectroscopy (XRF) analysis, it was determined to be Ce. 0.7 H 0.9 PMo 12 O 40 The yield was 46.9%.
[0041] Figure 1 The XRD patterns of cerium molybdenum phosphate prepared in Example 4 and the comparative example are shown below. Figure 1 It can be seen that the intensity of each characteristic peak in Example 4 is significantly stronger than that in the comparative example, and the peak shape is sharp, indicating that its crystallinity is high.
[0042] The total surface acidity, grain size, and specific surface area of the cerium molybdate phosphate prepared in Examples 1-5 and the comparative examples were characterized. The total surface acidity of the cerium molybdate phosphate was determined by NH3-TPD, the specific surface area by BET, and the grain size by SEM. The cerium molybdate phosphate prepared in Examples 1-5 and the comparative examples was used to catalyze the esterification reaction of propylene glycol monoethyl ether and acetic acid to prepare propylene glycol monoethyl ether acetate. The reaction was carried out in a fixed-bed reactor. The molar ratio of propylene glycol monoethyl ether to acetic acid was 1:1.3. 1.0 g of cerium molybdate phosphate catalyst was loaded into the middle of the fixed-bed reaction tube, with both ends filled with quartz wool and quartz sand. The reactants were introduced into the reactor via a sample pump at a volume hourly space velocity (VHSV) of 0.5 h⁻¹. -1 The reaction temperature was 100℃, and the yield of propylene glycol monoethyl ether acetate was obtained by chromatographic analysis. Characterization and experimental results are shown in Table 1.
[0043] The esterification reactions involved are as follows:
[0044]
[0045] Table 1
[0046]
[0047] As can be seen from the test results in Table 1, compared with the comparative example, the nano-molybdenum cerium phosphate prepared in Examples 1-5 of this invention has advantages such as small grain size, large specific surface area, high total acid content, and high yield. This is because supercritical oxygen fluid has high solubility and high diffusivity, which is conducive to sufficient and rapid contact and reaction between reactants. Furthermore, the product has high dispersibility, avoiding agglomeration between nanoparticles, thereby inhibiting the increase in grain size and increasing the number of exposed acidic active sites on the surface. Oxygen gas at atmospheric pressure has no solubility for salts. Therefore, the nano-molybdenum cerium phosphate prepared in Examples 1-5 all exhibited a higher yield of propylene glycol monoethyl ether acetate than the molybdenum phosphate catalyst in the comparative example, reaching over 95%.
[0048] This invention provides a catalyst for preparing propylene glycol monoethyl ether acetate, its preparation method, and its application. Many methods and approaches exist for implementing this technical solution; the above description is merely a preferred embodiment. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications should also be considered within the scope of protection of this invention. All components not explicitly stated in this embodiment can be implemented using existing technologies.
Claims
1. A method for preparing a catalyst for the preparation of propylene glycol monoethyl ether acetate, characterized in that, Includes the following steps: (1) Add cerium source and molybdenum phosphoric acid to a grinder and grind them together to obtain a solid-phase reaction mixture; (2) Place the solid reaction mixture in a supercritical crystallization kettle, introduce oxygen, maintain the temperature at 25-45 °C, and carry out the crystallization reaction under supercritical conditions to obtain the crystallized product; The pressure inside the supercritical crystallization reactor is 5–8 MPa, and the crystallization reaction time is 0.5–2 h. (3) Cool the crystallized product to room temperature, then wash it with deionized water, and finally dry it to obtain the product; The molecular formula of the obtained catalyst is Ce n H 3-3n PMo 12 O 40 , where n ranges from 0.1 to 0.
9.
2. The method for preparing the catalyst for preparing propylene glycol monoethyl ether acetate according to claim 1, characterized in that, In step (1), the cerium source is any one of cerium nitrate, cerium chloride, and cerium oxalate.
3. The method for preparing the catalyst for preparing propylene glycol monoethyl ether acetate according to claim 1, characterized in that, In step (1), the cerium source and molybdenum phosphoric acid are mixed at a molar ratio of 1.25 to 15:
1.
4. The method for preparing the catalyst for preparing propylene glycol monoethyl ether acetate according to claim 1, characterized in that, In step (1), the grinding and mixing process uses a grinding mill with a rotation speed of 600 r / min and a time of 30 to 45 min.
5. The method for preparing the catalyst for preparing propylene glycol monoethyl ether acetate according to claim 1, characterized in that, In step (2), the oxygen concentration introduced into the supercritical crystallization vessel is not less than 99.9%.
6. The method for preparing the catalyst for preparing propylene glycol monoethyl ether acetate according to claim 1, characterized in that, In step (3), deionized water is used for washing until the pH of the filtrate is 7.
0.
7. The method for preparing the catalyst for preparing propylene glycol monoethyl ether acetate according to claim 1, characterized in that, In step (3), the drying temperature is 100~120 ℃ and the time is 12~24 h.
8. The catalyst prepared by the method according to any one of claims 1 to 7, characterized in that, Its molecular formula is Ce n H 3-3n PMo 12 O 40 ; where n ranges from 0.1 to 0.
9.
9. The use of the catalyst of claim 8 in the preparation of propylene glycol monoethyl ether acetate.