A process for the preparation of cyclic ethers

Abstract

The application discloses a preparation method of cyclic ether. The preparation method comprises the following steps: reacting ethylene glycol with a catalyst to obtain 1,4-dioxane; and the catalyst is a phosphorus-modified hierarchical pore H-type molecular sieve. The catalyst provided by the application is applied to the dehydration reaction of ethylene glycol to prepare 1,4-dioxane, so as to improve the conversion rate of ethylene glycol and the selectivity of the generated 1,4-dioxane.

Description

Technical Field

[0001] This application relates to a method for preparing cyclic ethers, which belongs to the field of chemical engineering. Background Technology

[0002] In recent years, with continuous breakthroughs and improvements in coal-to-ethylene glycol industrial technology, my country's ethylene glycol production has increased rapidly. However, the quality of coal-to-ethylene glycol products still needs improvement, and currently it is difficult to meet the requirements of the polyester industry. Therefore, developing downstream products of ethylene glycol has considerable economic benefits and strategic significance. Among them, the process of preparing 1,4-dioxane from ethylene glycol has attracted widespread attention due to its strong competitiveness.

[0003] 1,4-Dioxane is an important chemical raw material widely used in industries such as paint, dyes, plasticizers, wetting agents, pharmaceuticals, and petrochemicals. Traditional industrial techniques for preparing 1,4-dioxane from ethylene glycol often use concentrated sulfuric acid or phosphoric acid as catalysts for the ethylene glycol dehydration reaction. This technology not only produces numerous byproducts and involves cumbersome post-processing, but also causes severe equipment corrosion and generates large amounts of waste acid and wastewater. Therefore, developing catalysts with high activity, high selectivity, good stability, and low cost and environmental friendliness is of great significance.

[0004] Solid acid catalysts have become a focus of research due to their high activity, high selectivity, and ease of separation. However, there are relatively few reports in the literature on solid acid catalysts used for the dehydration of ethylene glycol. With advancements in technology and increased environmental awareness, solid acid catalysts, which offer advantages such as recyclability and reusability, are gradually replacing traditional proton acid catalysts in chemical production. Summary of the Invention

[0005] This application of modified hierarchical porous molecular sieve catalysts to the preparation of 1,4-dioxane is of great significance. The catalysts exhibit good activity, high ethylene glycol conversion and 1,4-dioxane selectivity, and good stability.

[0006] According to one aspect of this application, a method for preparing a cyclic ether is provided, the method comprising: reacting ethylene glycol with a catalyst to obtain 1,4-dioxane;

[0007] The catalyst is a phosphorus-modified hierarchical H-type molecular sieve.

[0008] Ethylene glycol was reacted with a catalyst to yield 1,4-dioxane.

[0009] Optionally, the method for preparing the modified hierarchical porous molecular sieve includes the following steps:

[0010] (1) The molecular sieve is subjected to alkali treatment and hydrogen ion exchange to obtain a multi-level porous molecular sieve material;

[0011] (2) The multi-level porous molecular sieve material is immersed in a phosphorus source solution, stirred for I, dried for I, and calcined for I to obtain the phosphorus-modified multi-level porous H-type molecular sieve.

[0012] Optionally, in step (1), the alkali treatment includes the following steps: treating the molecular sieve with alkali solution, drying (II), and calcining (II).

[0013] Optionally, the solid-liquid ratio of the molecular sieve to the alkaline solution is 1:20-30 mol / L.

[0014] Optionally, the solid-liquid ratio of the molecular sieve to the alkaline solution is selected from any value among 1:20 mol / L, 1:25 mol / L, 1:30 mol / L, or any range between the two.

[0015] Optionally, the alkaline treatment is performed at a temperature of 65–90°C for a time of 0.5–1.5 hours.

[0016] Optionally, the temperature of the alkaline treatment is selected from any value of 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, or a range between any two of the above.

[0017] Optionally, the alkaline treatment time is selected from any value of 0.5 hours, 1 hour, 1.5 hours, or a range between any two of the above.

[0018] Optionally, the alkaline solution is selected from at least one of NaOH solution and KOH solution.

[0019] Optionally, the alkaline solution is a NaOH solution.

[0020] Optionally, the concentration of the alkaline solution is 0.1 to 0.3 mol / L.

[0021] Optionally, the concentration of the alkaline solution is selected from any value among 0.1 mol / L, 0.15 mol / L, 0.2 mol / L, 0.25 mol / L, 0.3 mol / L, or a range between any two of the above.

[0022] Optionally, the temperature of the second drying step is 80–130°C, and the drying time is 8–24 hours.

[0023] Optionally, the temperature of the drying II is selected from any value of 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, or a range between any two of the above.

[0024] Optionally, the drying time II is selected from any value of 8 hours, 12 hours, 16 hours, 20 hours, 24 hours, or a range between any two of the above.

[0025] Optionally, the calcination temperature II is 450–650°C, and the calcination time II is 1–6 hours.

[0026] Optionally, the calcination temperature II is selected from any value of 450°C, 500°C, 550°C, 600°C, 650°C, or a range between any two of the above.

[0027] Optionally, the calcination time II is selected from any value of 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, or a range between any two of the above.

[0028] Optionally, in step (1), the hydrogen ion exchange includes the following steps: treating the alkali-treated molecular sieve material with an ammonium salt solution, drying (III), and calcining (III).

[0029] Optionally, the ammonium salt solution treatment is carried out at a temperature of 65–90°C for 4–8 hours.

[0030] Optionally, the temperature for the ammonium salt solution treatment is selected from any value of 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, or a range between any two of the above.

[0031] Optionally, the treatment time of the ammonium salt solution is selected from any value of 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, or a range between any two of the above.

[0032] Optionally, the ammonium salt solution comprises an NH4NO3 solution.

[0033] Optionally, the ammonium salt solution is an NH4NO3 solution.

[0034] Optionally, the concentration of the NH4NO3 solution is 0.4–1.2 mol / L.

[0035] Optionally, the concentration of the NH4NO3 solution is selected from any value among 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1.0 mol / L, 1.1 mol / L, and 1.2 mol / L, or a range between any two of the above.

[0036] Optionally, the drying III process is carried out at a temperature of 80–130°C for 8–24 hours.

[0037] Optionally, the temperature of the drying III is selected from any value of 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, or a range between any two of the above.

[0038] Optionally, the drying time III is selected from any value of 8 hours, 12 hours, 16 hours, 20 hours, 24 hours, or a range between any two of the above.

[0039] Optionally, the calcination III is carried out at a temperature of 450–650°C for a time of 1–6 hours.

[0040] Optionally, the calcination temperature III is selected from any value of 450°C, 500°C, 550°C, 600°C, 650°C, or a range between any two of the above.

[0041] Optionally, the calcination time III is selected from any value of 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, or any range between two.

[0042] Optionally, in step (2), the phosphorus source solution is selected from ammonium phosphate and / or diammonium hydrogen phosphate.

[0043] Optionally, in step (2), the phosphorus source loading mass fraction in the phosphorus source solution is 4-12 wt%.

[0044] Optionally, the phosphorus source loading mass fraction in the phosphorus source solution is selected from any value of 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%, 11wt%, 12wt%, or a range between any two of the above.

[0045] Optionally, in step (2), the temperature of stirring I is 50-80°C, and the stirring time is 2-6 hours.

[0046] Optionally, the temperature of the stirring I is selected from any value of 50°C, 60°C, 70°C, 80°C, or a range between any two of the above.

[0047] Optionally, the stirring time I is selected from any value of 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, or a range between any two of the above.

[0048] Optionally, the temperature of drying I is 80–130°C, and the drying time is 8–24 hours.

[0049] Optionally, the temperature of the drying I is selected from any value of 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, or a range between any two of the above.

[0050] Optionally, the drying time I is selected from any value of 8 hours, 10 hours, 12 hours, 14 hours, 16 hours, 18 hours, 20 hours, 24 hours, or a range between any two of the above.

[0051] Optionally, the calcination temperature I is 450–650°C, and the calcination time I is 1–6 hours.

[0052] Optionally, the calcination temperature I is selected from any value of 450℃, 500℃, 550℃, 600℃, 650℃ or a range between any two of the above.

[0053] Optionally, the calcination time I is selected from any value of 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, or a range between any two of the above.

[0054] Optionally, the calcination atmosphere is N2, and the N2 gas flow rate is 10-30 ml / min.

[0055] Optionally, the gas flow rate of N2 is selected from any value of 10 ml / min, 20 ml / min, 30 ml / min or a range between any two of the above.

[0056] Optionally, the reaction temperature is 100–200°C.

[0057] Optionally, the reaction temperature is selected from any value of 100℃, 110℃, 120℃, 130℃, 140℃, 150℃, 160℃, 170℃, 180℃, 190℃, 200℃ or a range between any two of the above.

[0058] Optionally, the flow rate of N2 in the reaction is 0–30 ml / min.

[0059] Optionally, the flow rate of N2 in the reaction is any value among 0 ml / min, 5 ml / min, 10 ml / min, 15 ml / min, 20 ml / min, 25 ml / min, and 30 ml / min, or a range between any two of the above.

[0060] Optionally, the mass hourly space velocity (HHSV) of the reaction is 0.2–2 h⁻¹. -1 .

[0061] Optionally, the mass hourly space velocity (HHSV) of the reaction is 0.2 h⁻¹. -1 0.4h -1 0.6h -1 0.8h -1 1.0h -1 1.2h -1 1.4h -1 1.6h -1 1.8h -1 2.0h -1 Any value in or a range between any two of the above.

[0062] Optionally, in step (1), the molecular sieve is selected from at least one of hydrogen-type MCM-22 molecular sieve, hydrogen-type ZSM-35 molecular sieve, hydrogen-type ZSM-5 molecular sieve, hydrogen-type mercerized molecular sieve, hydrogen-type Y molecular sieve, and hydrogen-type Beta molecular sieve.

[0063] Optionally, the Si / Al ratio of the molecular sieve is 10 to 100.

[0064] Optionally, the Si / Al ratio of the molecular sieve is selected from any value of 10, 20, 30, 40, 50, 60, 70, 80, 90, 100 or a range between any two of the above.

[0065] The beneficial effects that this application can produce include:

[0066] 1) The catalyst provided in this application can be applied to the dehydration reaction of ethylene glycol to prepare 1,4-dioxane, and improves the conversion rate of ethylene glycol and the selectivity of the generated 1,4-dioxane.

[0067] 2) The preparation method of the catalyst provided in this application is stable, controllable, and reproducible.

[0068] 3) The method for preparing 1,4-dioxane by dehydration of ethylene glycol provided in this application uses the catalyst provided in this application, which has a fast reaction rate and high yield, and can be applied to large-scale production. Attached Figure Description

[0069] Figure 1 Catalyst 1 in Example 1 of this application # The reaction results of catalyst 1 # A combination of images depicting different temperaments. Detailed Implementation

[0070] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0071] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased through commercial channels.

[0072] The gas chromatograph used was an Agilent 7890B gas chromatograph.

[0073] In the embodiments of this application, the conversion rate and selectivity are calculated as follows:

[0074] The conversion rate and selectivity calculation formulas in the embodiments of this application are as follows (using ethylene glycol conversion rate as the evaluation index):

[0075] Ethylene glycol conversion rate = (initial carbon number of ethylene glycol - number of carbons of ethylene glycol in the product) * 100 / initial molar number of ethylene glycol

[0076] 1,4-Dioxane selectivity = number of carbon atoms in 1,4-dioxane * 100 / ∑(number of carbon atoms in 1,4-dioxane + number of carbon atoms in other products).

[0077] Example 1: Preparation of Catalyst

[0078] Maintaining the solution temperature at 65℃, the hydrogen-form ZSM-5 molecular sieve (Si / Al ratio of 30) was treated with a 0.1 mol / L NaOH solution for 0.5 hours, washed until neutral, dried at 80℃ for 24 hours, and calcined at 550℃ for 1 hour to obtain the Na-form hierarchical porous molecular sieve material. Maintaining the solution temperature at 90℃, the Na-form hierarchical porous molecular sieve material was treated with a 0.6 mol / L NH4NO3 solution for 6 hours, washed, dried at 130℃ for 8 hours, and calcined at 550℃ for 1 hour to obtain the hydrogen-form hierarchical porous molecular sieve material. The hierarchical porous molecular sieve material was impregnated in a 4 wt% diammonium hydrogen phosphate solution, stirred at 80℃ for 4 hours, dried at 120℃ for 12 hours, and calcined at 550℃ for 1 hour in an N2 atmosphere with a gas flow rate of 20 ml / min to obtain the modified hierarchical porous molecular sieve catalyst material, denoted as catalyst 1. # .

[0079] Following the steps below, adjust the type, amount, and reaction parameters of each raw material to obtain a series of catalysts numbered 1 to 28, denoted as Catalyst 1. # ~Catalyst 28 # As shown in Tables 1-3 below:

[0080] Table 1

[0081]

[0082]

[0083] Table 2

[0084]

[0085]

[0086] The columns in Tables 1 and 2 above are explained as follows:

[0087] Molecular sieve types: hydrogen-type MCM-22 molecular sieve (sieve 1), hydrogen-type ZSM-35 molecular sieve (sieve 2), hydrogen-type ZSM-5 molecular sieve (sieve 3), hydrogen-type mercerized molecular sieve (sieve 4), hydrogen-type Y molecular sieve (sieve 5), and hydrogen-type Beta molecular sieve (sieve 6).

[0088] Alkali solution types: NaOH (alkali 1), KOH (alkali 2).

[0089] Table 3

[0090]

[0091]

[0092] The explanations for each column in Table 3 above are as follows:

[0093] Phosphorus sources: ammonium phosphate (P1), diammonium hydrogen phosphate (P2).

[0094] Comparative Example 1

[0095] Maintaining the solution temperature at 65℃, the hydrogen-form ZSM-5 molecular sieve (Si / Al ratio of 30) was treated with a 0.1 mol / L NaOH solution for 0.5 hours, washed until neutral, dried at 80℃ for 24 hours, and calcined at 550℃ for 1 hour to obtain the Na-form hierarchical porous molecular sieve material. Maintaining the solution temperature at 90℃, the Na-form hierarchical porous molecular sieve material was treated with a 0.6 mol / L NH4NO3 solution for 6 hours, washed, dried at 130℃ for 8 hours, and calcined at 550℃ for 1 hour to obtain the hydrogen-form hierarchical porous molecular sieve material, denoted as Catalyst 29. # .

[0096] Example 2

[0097] Catalyst 1 prepared in Example 1 # ~Catalyst 29 # The dehydration of ethylene glycol to prepare 1,4-dioxane was carried out. Reaction parameters were varied, and after the reaction stabilized (6 hours), both the reactants and products were analyzed using online gas chromatography. The results are shown in Table 4. Gas chromatographic characterization: The composition of the ethylene glycol dehydration reaction products was analyzed using an Agilent 7890B gas chromatograph (FID detector, FFAP capillary column).

[0098] Table 4

[0099]

[0100]

[0101] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for preparing a cyclic ether, characterized in that, The preparation method includes: reacting ethylene glycol with a catalyst to obtain 1,4-dioxane; The catalyst is a phosphorus-modified hierarchical H-type molecular sieve; The preparation method of the modified hierarchical porous H-type molecular sieve includes the following steps: (1) The molecular sieve is subjected to alkali treatment and hydrogen ion exchange to obtain a multi-level porous molecular sieve material; (2) The multi-level porous molecular sieve material is immersed in a phosphorus source solution, stirred, dried and calcined to obtain the phosphorus-modified multi-level porous H-type molecular sieve; in, In step (1), the molecular sieve is selected from at least one of hydrogen-type MCM-22 molecular sieve, hydrogen-type ZSM-35 molecular sieve, hydrogen-type ZSM-5 molecular sieve, hydrogen-type mercerized molecular sieve, hydrogen-type Y molecular sieve, and hydrogen-type Beta molecular sieve. In step (2), the phosphorus source loading mass fraction in the phosphorus source solution is 4~12wt%; The calcination temperature is 450~650℃, and the calcination time is 1~6 hours; The reaction temperature is 100~200℃; The mass hourly space velocity (MSV) of the reaction is 0.2–2 h⁻¹. -1 ; The phosphorus source in the phosphorus source solution is selected from ammonium phosphate and / or diammonium hydrogen phosphate.

2. The preparation method according to claim 1, characterized in that, In step (2), the stirring temperature is 50~80℃ and the stirring time is 2~6 hours.

3. The preparation method according to claim 1, characterized in that, The drying temperature is 80~130℃, and the drying time is 8~24 hours.

4. The preparation method according to claim 1, characterized in that, The calcination atmosphere is N2, and the N2 gas flow rate is 10~30 ml / min.

5. The preparation method according to claim 1, characterized in that, The N2 flow rate in the reaction is 0~30 ml / min.

6. The preparation method according to claim 1, characterized in that, The Si / Al ratio of the molecular sieve is 10~100.

Images