A process for the preparation of 1,4-dioxane

Abstract

The application discloses a preparation method of 1,4-dioxane, which comprises the following steps: reacting ethylene glycol with a catalyst to obtain 1,4-dioxane; the catalyst is SO4 2‑ / HTaMoO6. The catalyst provided by the application is applied to the reaction of preparing 1,4-dioxane by dehydrating ethylene glycol, so as to improve the conversion rate of ethylene glycol and the selectivity of the generated 1,4-dioxane.

Description

TECHNICAL FIELD

[0001] The application relates to a preparation method of 1,4-dioxane, and belongs to the chemical field. BACKGROUND

[0002] 1,4-dioxane is an excellent solvent and is widely applied in the pharmaceutical, paint-making, petrochemical and other industries. A traditional production method is to synthesize 1,4-dioxane from ethylene glycol under the catalysis of sulfuric acid or phosphoric acid, and it is reported that heteropoly acids and their salts also have high catalytic activity for etherification of alcohols. However, these methods have many by-products, complicated post-treatment, great corrosion of equipment, difficult product refining, high production cost and large wastewater discharge.

[0003] In recent years, developing downstream products of ethylene glycol has very considerable economic benefits and significance. Among them, the process for preparing 1,4-dioxane from ethylene glycol has attracted widespread attention due to its great competitiveness. Therefore, it is of great significance to develop a catalyst with good activity, high selectivity, good stability and low cost and environmental protection.

[0004] Solid acid catalysts have become the focus of researchers due to their high activity, high selectivity and easy separation and other advantages. Literature reports that solid acid catalysts for catalyzing the dehydration reaction of ethylene glycol are still less. With the progress of science and technology and the improvement of people's environmental protection consciousness, in chemical production, a solid acid catalyst with the advantages of recyclability and reusability is gradually replacing traditional proton acid catalysts. SUMMARY

[0005] The application has great significance in applying a solid acid catalyst to the preparation process of 1,4-dioxane, and the catalyst has good activity, high ethylene glycol conversion rate and 1,4-dioxane selectivity, and good stability.

[0006] According to one aspect of the application, a preparation method of 1,4-dioxane is provided, and the preparation method comprises: reacting ethylene glycol with a catalyst to obtain 1,4-dioxane.

[0007] The catalyst is SO4 2- / HTaMoO6 obtained by impregnating HTaMoO6 with an H2SO4 solution.

[0008] Optionally, the preparation method of the SO4 2- / HTaMoO6 comprises the following steps:

[0009] (1) Proton exchange reaction of a solid acid catalyst in an acid solution, drying I, to obtain HTaMoO6;

[0010] (2) Impregnating HTaMoO6 with an H2SO4 solution, drying II, calcining, to obtain the SO4 2- / HTaMoO6;

[0011] The solid acid catalyst is KTaMoO6 or LiTaMoO6.

[0012] Optionally, in the step (2), the solid-liquid ratio of the HTaMoO6 to the H2SO4 solution is 1:20-30.

[0013] Optionally, the solid-liquid ratio of the HTaMoO6 to the H2SO4 solution is selected from any value or a range value between any two values of 1:20, 1:25, 1:30.

[0014] Optionally, in the step (2), the concentration of the H2SO4 solution is 0.1-2M.

[0015] Optionally, the concentration of the H2SO4 solution is selected from any value or a range value between any two values of 0.1M, 0.3M, 0.5M, 0.7M, 0.9M, 1.1M, 1.3M, 1.5M, 1.7M, 2M.

[0016] Optionally, in the step (1), the solid-liquid ratio of the solid acid catalyst to the acid solution is 1:20-30.

[0017] Optionally, the solid-liquid ratio of the solid acid catalyst to the acid solution is selected from any value or a range value between any two values of 1:20, 1:25, 1:30.

[0018] Optionally, in the step (1), the concentration of the acid solution is 2-10M.

[0019] Optionally, the concentration of the acid solution is selected from any value or a range value between any two values of 2M, 3M, 4M, 5M, 6M, 7M, 8M, 9M, 10M.

[0020] Optionally, in the step (1), the acid solution is selected from nitric acid and / or hydrochloric acid.

[0021] Optionally, in the step (1), the time of the proton exchange reaction is 24-96 hours.

[0022] Optionally, the time of the proton exchange reaction is selected from any value or a range value between any two values of 24 hours, 36 hours, 48 hours, 60 hours, 72 hours, 84 hours, 96 hours.

[0023] Optionally, the temperature of the drying I is 80℃-110℃, and the time of the drying I is 2-5 hours.

[0024] Optionally, the temperature of the drying I is selected from any value or a range between any two values of 80℃, 90℃, 100℃, 110℃.

[0025] Optionally, the time of the drying I is selected from any value or a range between any two values of 2 hours, 3 hours, 4 hours, 5 hours.

[0026] Optionally, the time of the impregnation is 4-24 hours.

[0027] Optionally, the time of the impregnation is selected from any value or a range between any two values of 4 hours, 8 hours, 12 hours, 16 hours, 20 hours, 24 hours.

[0028] Optionally, in the step (2), the temperature of the drying II is 80℃-110℃, and the time of the drying II is 2 hours-5 hours.

[0029] Optionally, the temperature of the drying II is selected from any value or a range between any two values of 80℃, 90℃, 100℃, 110℃.

[0030] Optionally, the time of the drying II is selected from any value or a range between any two values of 2 hours, 3 hours, 4 hours, 5 hours.

[0031] Optionally, the temperature of the calcination is 400℃-600℃, and the time of the calcination is 3 hours-6 hours.

[0032] Optionally, the temperature of the calcination is selected from any value or a range between any two values of 400℃, 450℃, 500℃, 550℃, 600℃.

[0033] Optionally, the time of the calcination is selected from any value or a range between any two values of 3 hours, 4 hours, 5 hours, 6 hours.

[0034] Optionally, the temperature of the reaction is 100-200℃; the flow rate of N2 in the reaction is 0-30ml / min; the mass space velocity of the reaction is 0.2-2h -1 ;

[0035] Optionally, the temperature of the reaction is selected from any value or a range between any two values of 100℃, 110℃, 120℃, 130℃, 140℃, 150℃, 160℃, 170℃, 180℃, 190℃, 200℃.

[0036] Optionally, the N2 flow rate in the reaction is any value selected from 0 ml / min, 5 ml / min, 10 ml / min, 15 ml / min, 20 ml / min, 25 ml / min, 30 ml / min, or a range value between any two of them.

[0037] Optionally, the mass space velocity of the reaction is any value selected from 0.2 h-1, 0.4 h-1, 0.6 h-1, 0.8 h-1, 1.0 h-1, 1.2 h-1, 1.4 h-1, 1.6 h-1, 1.8 h-1, 2.0 h-1, or a range value between any two of them. -1 -1 -1 -1 -1 -1 -1 -1 -1 -1

[0038] In the present application, the preparation method of the SO4- / HTaMoO6 includes the following steps: 2-

[0039] KTaMoO6 (LiTaMoO6) is prepared by a molten salt method, and then the KTaMoO6 (LiTaMoO6) is subjected to a proton exchange reaction in an acid solution, washed, dried, and obtained is the HTaMoO6;

[0040] The HTaMoO6 is impregnated with an H2SO4 solution, filtered, dried, and calcined to obtain the solid acid catalyst SO4- / HTaMoO6. 2-

[0041] The specific steps for preparing KTaMoO6 (LiTaMoO6) by a molten salt method include:

[0042] 1) A tantalum source, a molybdenum source, a molten salt, and a solvent are mixed, ultrasonically treated, ground, and dried to obtain a mixture;

[0043] 2) The mixture obtained in step 1) is calcined and washed to obtain KTaMoO6 (LiTaMoO6);

[0044] The tantalum source is at least one selected from tantalum pentoxide and tantalum powder;

[0045] The molybdenum source is at least one selected from molybdenum oxide and molybdenum powder;

[0046] The molten salt is K2CO3 or LiCO3.

[0047] The molar ratio of the tantalum source to the molybdenum source is 1:(0.9-2);

[0048] ​​​​​​​​​​​​Optionally, the molar ratio of the tantalum source to the molybdenum source is any value selected from 1:0.9, 1:1, 1:1.9, 1:2, or a range value between any two of them.

[0049] Optionally, the molar ratio of the tantalum source to the molten salt is (1-2):(0.9-2).

[0050] Optionally, the molar ratio of the tantalum source to the molten salt is any value selected from 1:0.9, 1:1, 1:1.9, 1:2, 2:0.9, 2:1, or a range value between any two of them.

[0051] Optionally, the solvent is one of methanol, ethanol, and acetone.

[0052] Optionally, the drying temperature in step 1) is 80-110℃, and the drying time is 2-5 hours.

[0053] Optionally, the drying temperature is any value selected from 80℃, 90℃, 100℃, and 110℃, or a range value between any two of them.

[0054] Optionally, the drying time is any value selected from 2 hours, 3 hours, 4 hours, and 5 hours, or a range value between any two of them.

[0055] Optionally, the calcination temperature in step 2) is 600-1200℃, and the calcination time is 12-48 hours.

[0056] Optionally, the calcination temperature is any value selected from 600℃, 700℃, 800℃, 900℃, 1000℃, 1100℃, and 1200℃, or a range value between any two of them.

[0057] Optionally, the calcination time is any value selected from 12 hours, 24 hours, 36 hours, and 48 hours, or a range value between any two of them.

[0058] The beneficial effects that can be produced by the present application include:

[0059] 1) The solid acid catalyst SO4 2- / HTaMoO6 provided by the present application can be applied in the reaction of preparing 1,4-dioxane from the dehydration of ethylene glycol, and improves the conversion rate of ethylene glycol and the selectivity of the generated 1,4-dioxane.

[0060] 2) The preparation method of the solid acid catalyst SO4 2- / HTaMoO6 provided by the present application is stable, controllable, and has good reproducibility.

[0061] 3) The method for preparing 1,4-dioxane by dehydration of ethylene glycol provided in the present application uses the solid acid catalyst provided in the present application, has fast reaction speed, high yield, and can be applied to large-scale production. BRIEF DESCRIPTION OF DRAWINGS

[0062] Figure 1 X-ray powder diffraction pattern of HTaMoO6 in the synthesis process of catalyst 1 in Example 1 of the present application. DETAILED DESCRIPTION

[0063] The present application will be described in detail below with reference to Examples, but the present application is not limited to these Examples.

[0064] The raw materials in the Examples of the present application are all purchased through commercial channels unless otherwise specified.

[0065] Among them, the gas chromatograph is a 7890B gas chromatograph of Agilent Company.

[0066] The conversion rate and selectivity in the Examples of the present application are calculated as follows:

[0067] The conversion rate and selectivity in the Examples of the present application are calculated as follows (taking the conversion rate of ethylene glycol as the evaluation index):

[0068] Ethylene glycol conversion rate = (initial carbon number of ethylene glycol - carbon number of ethylene glycol in the product) * 100 / initial moles of ethylene glycol

[0069] 1,4-dioxane selectivity = carbon number of 1,4-dioxane * 100 / ∑ (carbon number of 1,4-dioxane + carbon number of other products).

[0070] XRD characterization:

[0071] Miniflex 600 X-ray diffractometer was used, Cu target, for catalyst 1 # Powder diffraction, the diffraction peak of HTaMoO6 in the synthesis process of catalyst 1 is consistent with the characteristic peak of HTaMoO6 (as shown in Figure 1

[0072] Preparation of catalyst in Example 1

[0073] ​A mixture of molybdenum pentoxide and molybdenum oxide with a molar ratio of 1:2 was mixed with molten salt K2CO3 in an ethanol solution (molar ratio of tantalum source to molten salt was 1:1), and the mixture was ground after ultrasonic treatment, dried in an oven at 100°C for 4 hours, and calcined in a high-temperature furnace at 1000°C for 24 hours to obtain a KTaMoO6 sample. The KTaMoO6 sample was mixed with nitric acid (concentration of 6M) at a solid-liquid ratio of 1:20 to perform a proton exchange reaction for 72 hours, dried in an oven at 100°C for 4 hours, impregnated with 0.5M H2SO4 solution (solid-liquid ratio of 1:20) for 8 hours, filtered, dried in an oven at 100°C for 4 hours, and calcined at 500°C for 3 hours to obtain a solid acid catalyst 1, i.e., SO4 2- / HTaMoO6. Figure 1 As can be seen from the X-ray powder diffraction pattern, the peaks are characteristic of HTaMoO6.

[0074] Example 2

[0075] A mixture of molybdenum pentoxide and molybdenum oxide with a molar ratio of 1:2 was mixed with molten salt K2CO3 in an ethanol solution (molar ratio of tantalum source to molten salt was 1:1), and the mixture was ground after ultrasonic treatment, dried in an oven at 100°C for 4 hours, and calcined in a high-temperature furnace at 1000°C for 24 hours to obtain a KTaMoO6 sample. The KTaMoO6 sample was mixed with nitric acid (concentration of 6M) at a solid-liquid ratio of 1:20 to perform a proton exchange reaction for 72 hours, dried in an oven at 100°C for 4 hours, impregnated with 0.5M H2SO4 solution (solid-liquid ratio of 1:20) for 8 hours, filtered, dried in an oven at 100°C for 4 hours, and calcined at 500°C for 3 hours to obtain a solid acid catalyst 1, i.e., SO4 2- / HTaMoO6.

[0076] Example 3

[0077] A mixture of molybdenum pentoxide and molybdenum oxide with a molar ratio of 1:2 was mixed with molten salt K2CO3 in an ethanol solution (molar ratio of tantalum source to molten salt was 1:1), and the mixture was ground after ultrasonic treatment, dried in an oven at 100°C for 4 hours, and calcined in a high-temperature furnace at 1000°C for 24 hours to obtain a KTaMoO6 sample. The KTaMoO6 sample was mixed with nitric acid (concentration of 6M) at a solid-liquid ratio of 1:20 to perform a proton exchange reaction for 72 hours, dried in an oven at 100°C for 4 hours, impregnated with 0.5M H2SO4 solution (solid-liquid ratio of 1:20) for 8 hours, filtered, dried in an oven at 100°C for 4 hours, and calcined at 500°C for 3 hours to obtain a solid acid catalyst 1, i.e., SO4 2- / HTaMoO6.

[0078] Example 4

[0079] A mixture of tantalum powder and molybdenum powder with a molar ratio of 1:0.9 was mixed with molten salt LiC03in an ethanol solution (molar ratio of tantalum source to molten salt was 1:0.9), and the mixture was ground after ultrasonic treatment and dried in an oven at 80°C for 3 hours. The sample was calcined in a high-temperature furnace at 900°C for 12 hours to obtain a LiTaMoO6sample. The LiTaMoO6sample was mixed with hydrochloric acid (concentration of 10M) at a solid-liquid ratio of 1:20 to perform a proton exchange reaction for 24 hours, and then dried in an oven at 80°C for 3 hours. The HTaMoO6was immersed in a 0.3M H2SO4solution (solid-liquid ratio of 1:20) for 20 hours, filtered, dried in an oven at 80°C for 3 hours, and then calcined at 600°C for 3 hours to obtain a solid acid catalyst 4, i.e., SO4 2- / HTaMoO6.

[0080] Example 5

[0081] A mixture of tantalum pentoxide and molybdenum oxide with a molar ratio of 1:2 was mixed with molten salt K2CO3in an ethanol solution (molar ratio of tantalum source to molten salt was 1:1), and the mixture was ground after ultrasonic treatment and dried in an oven at 100°C for 3 hours. The sample was calcined in a high-temperature furnace at 700°C for 48 hours to obtain a KTaMoO6sample. The KTaMoO6sample was mixed with nitric acid (concentration of 7M) at a solid-liquid ratio of 1:20 to perform a proton exchange reaction for 72 hours, and then dried in an oven at 100°C for 3 hours. The HTaMoO6was immersed in a 0.5M H2SO4solution (solid-liquid ratio of 1:20) for 8 hours, filtered, dried in an oven at 100°C for 3 hours, and then calcined at 400°C for 6 hours to obtain a solid acid catalyst 5, i.e., SO4 2- / HTaMoO6.

[0082] Example 6

[0083] A mixture of tantalum powder and molybdenum oxide with a molar ratio of 1:1 was mixed with molten salt K2CO3in a methanol solution (molar ratio of tantalum source to molten salt was 2:0.9), and the mixture was ground after ultrasonic treatment and dried in an oven at 110°C for 5 hours. The sample was calcined in a high-temperature furnace at 1100°C for 24 hours to obtain a KTaMoO6sample. The KTaMoO6sample was mixed with hydrochloric acid (concentration of 5M) at a solid-liquid ratio of 1:25 to perform a proton exchange reaction for 60 hours, and then dried in an oven at 110°C for 5 hours. The HTaMoO6was immersed in a 1.1M H2SO4solution (solid-liquid ratio of 1:25) for 4 hours, filtered, dried in an oven at 110°C for 5 hours, and then calcined at 500°C for 3 hours to obtain a solid acid catalyst 6, i.e., SO4 2- / HTaMoO6.

[0084] Example 7

[0085] The tantalum powder and molybdenum powder with a molar ratio of 1:0.9 were mixed with molten salt LiCO3 in an ethanol solution (molar ratio of tantalum source to molten salt was 1:0.9), ground after ultrasonic treatment, dried in an oven at 90°C for 4 hours, and then calcined in a high-temperature furnace at 600°C for 12 hours to obtain a LiTaMoO6 sample. The LiTaMoO6 sample was mixed with hydrochloric acid (concentration of 3M) at a solid-liquid ratio of 1:30 to perform a proton exchange reaction for 96 hours, dried in an oven at 90°C for 4 hours, immersed in a 1.3M H2SO4 solution for 4 hours (solid-liquid ratio of 1:30), filtered, dried in an oven at 90°C for 4 hours, and then calcined at 550°C for 4 hours to obtain a solid acid catalyst 7, i.e., SO4 2- / HTaMoO6.

[0086] Example 8

[0087] The tantalum pentoxide and molybdenum powder with a molar ratio of 1:1.9 were mixed with molten salt LiCO3 in a methanol solution (molar ratio of tantalum source to molten salt was 1:2), ground after ultrasonic treatment, dried in an oven at 80°C for 2 hours, and then calcined in a high-temperature furnace at 1000°C for 36 hours to obtain a LiTaMoO6 sample. The LiTaMoO6 sample was mixed with nitric acid (concentration of 2M) at a solid-liquid ratio of 1:20 to perform a proton exchange reaction for 60 hours, dried in an oven at 80°C for 2 hours, immersed in a 1.7M H2SO4 solution for 12 hours (solid-liquid ratio of 1:20), filtered, dried in an oven at 80°C for 2 hours, and then calcined at 600°C for 5 hours to obtain a solid acid catalyst 8, i.e., SO4 2- / HTaMoO6.

[0088] Example 9

[0089] The tantalum powder and molybdenum oxide with a molar ratio of 1:1 were mixed with molten salt K2CO3 in an ethanol solution (molar ratio of tantalum source to molten salt was 2:1), ground after ultrasonic treatment, dried in an oven at 100°C for 5 hours, and then calcined in a high-temperature furnace at 1200°C for 24 hours to obtain a KTaMoO6 sample. The KTaMoO6 sample was mixed with hydrochloric acid (concentration of 9M) at a solid-liquid ratio of 1:25 to perform a proton exchange reaction for 72 hours, dried in an oven at 100°C for 5 hours, immersed in a 2M H2SO4 solution for 16 hours (solid-liquid ratio of 1:25), filtered, dried in an oven at 100°C for 5 hours, and then calcined at 450°C for 3 hours to obtain a solid acid catalyst 9, i.e., SO4 2- / HTaMoO6.

[0090] Example 10

[0091] A mixture of tantalum pentoxide and molybdenum oxide with a molar ratio of 1:2 was mixed with molten salt K2CO3 in acetone solution (molar ratio of tantalum source to molten salt was 1:1), and the mixture was ground after ultrasonic treatment, dried in an oven at 110°C for 3 hours, and calcined in a high-temperature furnace at 700°C for 12 hours to obtain a KTaMoO6 sample. The KTaMoO6 sample was mixed with nitric acid (concentration 6M) at a solid-liquid ratio of 1:20 to perform a proton exchange reaction for 48 hours, dried in an oven at 110°C for 3 hours, impregnated with 1.5M H2SO4 solution for 8 hours (solid-liquid ratio 1:20), filtered, dried in an oven at 110°C for 3 hours, and calcined at 400°C for 6 hours to obtain a solid acid catalyst 10, i.e., SO4 2- / HTaMoO6.

[0092] Example 11

[0093] A mixture of tantalum powder and molybdenum powder with a molar ratio of 1:1 was mixed with molten salt LiCO3 in ethanol solution (molar ratio of tantalum source to molten salt was 1:0.9), and the mixture was ground after ultrasonic treatment, dried in an oven at 80°C for 2 hours, and calcined in a high-temperature furnace at 900°C for 48 hours to obtain a LiTaMoO6 sample. The LiTaMoO6 sample was mixed with nitric acid (concentration 4M) at a solid-liquid ratio of 1:30 to perform a proton exchange reaction for 36 hours, dried in an oven at 80°C for 2 hours, impregnated with 0.1M H2SO4 solution for 8 hours (solid-liquid ratio 1:30), filtered, dried in an oven at 80°C for 2 hours, and calcined at 500°C for 5 hours to obtain a solid acid catalyst 11, i.e., SO4 2- / HTaMoO6.

[0094] Example 12

[0095] A mixture of tantalum powder and molybdenum oxide with a molar ratio of 1:0.9 was mixed with molten salt K2CO3 in ethanol solution (molar ratio of tantalum source to molten salt was 2:0.9), and the mixture was ground after ultrasonic treatment, dried in an oven at 110°C for 4 hours, and calcined in a high-temperature furnace at 1000°C for 36 hours to obtain a KTaMoO6 sample. The KTaMoO6 sample was mixed with hydrochloric acid (concentration 8M) at a solid-liquid ratio of 1:20 to perform a proton exchange reaction for 84 hours, dried in an oven at 110°C for 4 hours, impregnated with 0.5M H2SO4 solution for 20 hours (solid-liquid ratio 1:20), filtered, dried in an oven at 110°C for 4 hours, and calcined at 450°C for 4 hours to obtain a solid acid catalyst 12, i.e., SO4 2- / HTaMoO6.

[0096] Example 13

[0097] LiTaMoO6sample. The LiTaMoO6sample was mixed with hydrochloric acid (concentration 7M) at a solid-liquid ratio of 1:30 to perform a proton exchange reaction for 96 hours, and then dried in an oven at 90°C for 3 hours. The HTaMoO6was immersed in a 0.9M H2SO4solution (solid-liquid ratio 1:30) for 8 hours, filtered, dried in an oven at 90°C for 3 hours, and then calcined at 550°C for 5 hours to obtain a solid acid catalyst 13, i.e., SO4 2- / HTaMoO6.

[0098] Example 14

[0099] LiTaMoO6sample. The LiTaMoO6sample was mixed with hydrochloric acid (concentration 7M) at a solid-liquid ratio of 1:30 to perform a proton exchange reaction for 96 hours, and then dried in an oven at 90°C for 3 hours. The HTaMoO6was immersed in a 0.9M H2SO4solution (solid-liquid ratio 1:30) for 8 hours, filtered, dried in an oven at 90°C for 3 hours, and then calcined at 550°C for 5 hours to obtain a solid acid catalyst 13, i.e., SO4 2- / HTaMoO6.

[0100] Example 15

[0101] LiTaMoO6sample. The LiTaMoO6sample was mixed with hydrochloric acid (concentration 7M) at a solid-liquid ratio of 1:30 to perform a proton exchange reaction for 96 hours, and then dried in an oven at 90°C for 3 hours. The HTaMoO6was immersed in a 0.9M H2SO4solution (solid-liquid ratio 1:30) for 8 hours, filtered, dried in an oven at 90°C for 3 hours, and then calcined at 550°C for 5 hours to obtain a solid acid catalyst 13, i.e., SO4 2- / HTaMoO6.

[0102] Example 16

[0103] The molar ratio of 1:1.9 of tantalum pentoxide and molybdenum oxide was mixed with molten salt K2CO3 in a methanol solution (molar ratio of tantalum source to molten salt was 1:1), and the mixture was ground after ultrasonic treatment, dried in an oven at 100°C for 5 hours; then placed in a high-temperature furnace at 1100°C for calcination for 48 hours, to obtain a KTaMoO6 sample. The KTaMoO6 sample was mixed with nitric acid (concentration 6M) at a solid-liquid ratio of 1:30 to perform a proton exchange reaction for 60 hours, dried in an oven at 100°C for 5 hours; 0.3M H2SO4 solution was used to impregnate HTaMoO6 (solid-liquid ratio 1:30) for 8 hours, filtered, dried in an oven at 100°C for 5 hours, and then calcined at 500°C for 6 hours to obtain a solid acid catalyst 16, i.e. SO4 2- / HTaMoO6.

[0104] Comparative Example 1

[0105] The molar ratio of 1:2 of tantalum pentoxide and molybdenum oxide was mixed with molten salt K2CO3 in an ethanol solution (molar ratio of tantalum source to molten salt was 1:1), and the mixture was ground after ultrasonic treatment, dried in an oven at 100°C for 4 hours; then placed in a high-temperature furnace at 1000°C for calcination for 24 hours, to obtain a KTaMoO6 sample. The KTaMoO6 sample was mixed with nitric acid (concentration 6M) at a solid-liquid ratio of 1:20 to perform a proton exchange reaction for 72 hours, dried in an oven at 100°C for 4 hours, to obtain HTaMoO6.

[0106] Example 17

[0107] The catalysts 1, 5, 8, 11, 13 and 16 prepared in Examples 1, 5, 8, 11, 13 and 16 were used to perform a reaction of dehydration of ethylene glycol to prepare 1, 4-dioxane, and the reaction parameters were changed, and after the reaction was stable (for 6 hours), the reaction raw materials and products were analyzed by gas phase online chromatography. The reaction results are shown in Table 1.

[0108] Gas chromatography characterization:

[0109] Agilent 7890B gas chromatography (FID detector, FFAP capillary column) was used to analyze the composition of the product of the ethylene glycol dehydration reaction.

[0110] Table 1

[0111]

[0112]

[0113] The above merely describes several embodiments of the present application, and does not limit the present application in any form. Although the present application is disclosed with the preferred embodiments, it is not intended to limit the present application. Any skilled person in the art can make some changes or modifications to the disclosed technical contents without departing from the scope of the technical solutions of the present application, and the equivalent embodiments are equivalent to the equivalent embodiments, which are within the scope of the technical solutions.

Claims

1. A method for preparing 1,4-dioxane, characterized in that, The preparation method includes: reacting ethylene glycol with a catalyst to obtain 1,4-dioxane; The catalyst is SO4 obtained by impregnating HTaMoO6 with H2SO4 solution. 2- / HTaMoO6.

2. The preparation method according to claim 1, characterized in that, The SO4 2- The preparation method of / HTaMoO6 includes the following steps: (1) The solid acid catalyst was subjected to a proton exchange reaction in an acid solution and dried to obtain HTaMoO6; (2) Impregnate HTaMoO6 with H2SO4 solution, dry and calcine to obtain SO4. 2- / HTaMoO6; The solid acid catalyst is KTaMoO6 or LiTaMoO6.

3. The preparation method according to claim 2, characterized in that, In step (2), the solid-liquid ratio of the HTaMoO6 to the H2SO4 solution is 1:20~30.

4. The preparation method according to claim 2, characterized in that, In step (2), the concentration of the H2SO4 solution is 0.1~2 M.

5. The preparation method according to claim 2, characterized in that, In step (1), the solid-liquid ratio of the solid acid catalyst to the acid solution is 1:20~30.

6. The preparation method according to claim 2, characterized in that, In step (1), the concentration of the acid solution is 2~10M.

7. The preparation method according to claim 2, characterized in that, In step (1), the acid solution is selected from nitric acid and / or hydrochloric acid.

8. The preparation method according to claim 2, characterized in that, In step (1), the proton exchange reaction takes 24 to 96 hours.

9. The preparation method according to claim 2, characterized in that, In step (1), the drying temperature is 80℃~110℃ and the drying time is 2 hours~5 hours.

10. The preparation method according to claim 2, characterized in that, In step (2), the soaking time is 4 to 24 hours.

11. The preparation method according to claim 2, characterized in that, In step (2), the drying temperature is 80℃~110℃ and the drying time is 2 hours~5 hours.

12. The preparation method according to claim 2, characterized in that, In step (2), the calcination temperature is 400°C to 600°C and the calcination time is 3 to 6 hours.

13. The preparation method according to claim 1, characterized in that, The reaction temperature is 100~200℃; The N2 flow rate in the reaction is 0~30 ml / min; The mass hourly space velocity (MSV) of the reaction is 0.2–2 h⁻¹. -1 .

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