Method for preparing ether by using solid base catalyst

Abstract

The invention discloses a method for preparing ether by using a solid base catalyst, which comprises the following steps: carrying out contact reaction on raw materials of diethylene glycol and ethylene oxide with a catalyst to obtain a reaction material containing triethylene glycol and tetraethylene glycol, and separating and purifying the reaction material in a rectifying tower to obtain a tetraethylene glycol product and co-produce triethylene glycol. The catalyst is KOH / MgAl2O4-CaO, and the preparation method comprises the following steps: preparing MgAl2O4 by adopting a hydrothermal method, loading CaO on the surface of MgAl2O4 by adopting an excessive impregnation method, and finally impregnating by adopting a KOH solution to obtain the solid composite catalyst. The catalyst provided by the invention is applied to a reaction for preparing triethylene glycol and tetraethylene glycol through a reaction of diethylene glycol and ethylene oxide.

Description

Technical Field

[0001] The present application relates to a method for preparing ether using a solid base catalyst, and belongs to the technical field of chemical industry. Background Art

[0002] Triethylene glycol (molecular formula: HOC 2 H 4 OC 2 H 4 OC 2 H 4 OH) is one of the important diols, mainly used as solvents, desiccants, lubricants and plasticizers. Triethylene glycol is easy to dehydrate from air and other gases, and is currently widely used as a natural gas dehydrating agent. Tetraethylene glycol is a very valuable chemical product, mainly used as an extraction solvent for extracting aromatic hydrocarbons (benzene, toluene and xylene) from catalytic reforming oil and cracking light tar in refineries. It can also be used as a raw material for synthesizing tetraethylene glycol alkyl ethers and polyester resins. In the aromatic extraction process using glycols as extraction solvents, tetraethylene glycol is a high-efficiency and energy-saving aromatic extraction agent. The preparation method of triethylene glycol and tetraethylene glycol generally uses ethylene oxide and diethylene glycol as reaction raw materials, uses alkaline substances such as alkali metal hydroxides as catalysts, and undergoes a step-by-step addition reaction under certain reaction temperature and pressure conditions to obtain a product with the structural formula HO(C 2 H 5 The method can obtain products mainly composed of triethylene glycol and tetraethylene glycol by optimizing the process conditions such as raw material ratio, and then obtain tetraethylene glycol products with high industrial utilization value through separation and purification. Chinese patent CN1145355A discloses a method for co-producing triethylene glycol, tetraethylene glycol (molecular formula: HOC 2 H 4 OC 2 H 4 OC 2 H 4 OC 2 H 4 A new method for preparing triethylene glycol (ethylene glycol) is disclosed, which uses diethylene glycol as an initiator, and reacts with ethylene oxide in the presence of an alkaline earth metal / alkali metal catalyst; and then separates the obtained product through distillation. The limitations of this method are: the mixed product contains a large amount of metal ions, and the polyether is prone to yellowing and breaking at high temperatures, which reduces the yield of triethylene glycol and tetraethylene glycol; at the same time, the distillation substrate is dark in color and difficult to recycle, which not only causes a waste of resources, but also brings potential environmental pollution. Summary of the invention

[0003] Preparation of KOH / MgAl 2 O 4-CaO catalyst and its application in the preparation process of triethylene glycol and tetraethylene glycol has great significance. The catalyst has good activity, high diethylene glycol conversion rate and high selectivity of triethylene glycol and tetraethylene glycol, and good stability. The obtained reaction material containing triethylene glycol and tetraethylene glycol is separated and purified in a distillation tower to obtain tetraethylene glycol product and co-produce triethylene glycol.

[0004] According to one aspect of the present application, there is provided a method for preparing ether using a solid base catalyst, the method comprising:

[0005] The raw material containing diethylene glycol and ethylene oxide is contacted with a solid composite catalyst to react to obtain triethylene glycol and tetraethylene glycol;

[0006] The solid composite catalyst is KOH / MgAl 2 O 4 -CaO.

[0007] Optionally, the preparation method of the ether comprises: using diethylene glycol and ethylene oxide as raw materials, reacting the raw materials with KOH / MgAl 2 O 4 -CaO catalyst to react and obtain a reaction material containing triethylene glycol and tetraethylene glycol, which is then sent into a distillation tower for separation and purification to obtain a tetraethylene glycol product and co-produce triethylene glycol.

[0008] Optionally, the KOH / MgAl 2 O 4 The preparation method of -CaO comprises the following steps:

[0009] (1) MgAl was prepared by hydrothermal method 2 O 4 ;

[0010] (2) Excessive impregnation of CaO on MgAl 2 O 4 Surface, MgAl 2 O 4 -CaO;

[0011] (3) Impregnation of MgAl with KOH solution 2 O 4 -CaO, to obtain KOH / MgAl 2 O 4 -CaO.

[0012] Optionally, the KOH / MgAl 2 O 4 The preparation method of -CaO comprises preparing MgAl by hydrothermal method 2 O 4 , CaO was loaded on MgAl by excess impregnation method. 2 O4 The surface is then impregnated with a KOH solution to obtain the solid composite catalyst.

[0013] Optionally, the KOH / MgAl 2 O 4 -CaO, CaO and MgAl 2 O 4 The mass ratio is 0.1~2.5:1.

[0014] Optionally, the KOH / MgAl 2 O 4 -CaO, CaO and MgAl 2 O 4 The mass ratio is independently selected from any value of 0.1:1, 0.5:1, 1:1, 1.5:1, 2:1, 2.5:1, or a range between any two of the above values.

[0015] Optionally, in step (1), the MgAl 2 O 4 The preparation method comprises:

[0016] A mixture containing magnesium nitrate, aluminum nitrate, sodium hydroxide and sodium carbonate is subjected to hydrothermal reaction, dried and calcined to obtain the MgAl 2 O 4 .

[0017] Optionally, the hydrothermal method is used to prepare MgAl 2 O 4 The specific steps include:

[0018] (1) dissolving magnesium nitrate and aluminum nitrate in water to obtain solution A; dissolving sodium hydroxide and sodium carbonate in water to obtain solution B;

[0019] (2) Add solution B to solution A under stirring and stir evenly;

[0020] (3) subjecting the suspension obtained in step (2) to hydrothermal crystallization;

[0021] (4) filtering, washing, and drying the solid obtained in step (3), and then calcining it under air atmosphere to obtain MgAl 2 O 4 .

[0022] Optionally, the molar ratio of the magnesium nitrate to the aluminum nitrate is (0.9-1):2,

[0023] The molar amount of the magnesium nitrate is calculated based on the molar amount of the magnesium element, and the molar amount of the aluminum nitrate is calculated based on the molar amount of the aluminum element.

[0024] Optionally, the molar ratio of the magnesium nitrate to the aluminum nitrate is independently selected from any value of 0.9:2, 0.95:2, 1:2 or a range between any two of the above; the molar amount of the magnesium nitrate is calculated based on the molar amount of the magnesium element, and the molar amount of the aluminum nitrate is calculated based on the molar amount of the aluminum element.

[0025] Optionally, the molar ratio of the sodium hydroxide to the total amount of the magnesium element and the aluminum element is (1.5-2.5):1.

[0026] Optionally, the molar ratio of the sodium hydroxide to the total amount of the magnesium element and the aluminum element is independently selected from any value of 1.5:1, 2:1, 2.5:1 or a range value between any two of the above.

[0027] Optionally, the molar ratio of the sodium carbonate to the total amount of the magnesium element and the aluminum element is (0.4-1.7):1.

[0028] Optionally, the molar ratio of the sodium carbonate to the total amount of the magnesium element and the aluminum element is independently selected from any value among 0.4:1, 0.6:1, 0.8:1, 1.0:1, 1.2:1, 1.4:1, 1.7:1 or a range between any two of the above.

[0029] Optionally, in step (2), the stirring condition is: stirring at room temperature for 1 to 2 hours;

[0030] Optionally, the stirring condition I is: stirring at room temperature is independently selected from any value of 1h, 1.2h, 1.5h, 1.8h, 2h or a range between any two of the above.

[0031] Optionally, the temperature of the hydrothermal reaction is 110-130° C., and the time of the hydrothermal reaction is 16-24 hours.

[0032] Optionally, the temperature of the hydrothermal reaction is independently selected from any value among 110° C., 120° C., 130° C., or a range between any two of the above values.

[0033] Optionally, the time of the hydrothermal reaction is independently selected from any value among 16 h, 18 h, 20 h, 22 h, 24 h, or a range between any two of the above.

[0034] Optionally, the drying temperature of I is 50 to 80° C., and the drying time of I is 12 to 24 hours.

[0035] Optionally, the drying temperature I is independently selected from any value of 50°C, 60°C, 70°C, 80°C or a range between any two of the above values.

[0036] Optionally, the drying time I is independently selected from any value among 12h, 16h, 20h, 24h or a range value between any two of the above.

[0037] Optionally, the temperature of the calcination I is 500 to 1300° C., and the time of the calcination I is 2 to 4 hours.

[0038] Optionally, the temperature of the calcination I is independently selected from any value of 500°C, 600°C, 700°C, 800°C, 900°C, 1000°C, 1100°C, 1200°C, 1300°C or a range between any two of the above values.

[0039] Optionally, the calcination time I is independently selected from any value among 2h, 3h, 4h or a range between any two of the above.

[0040] Optionally, in step (2), the MgAl 2 O 4 The preparation method of -CaO comprises:

[0041] Containing calcium source, MgAl 2 O 4 , a mixture of solvents II, stirring II, drying II, calcining II, to obtain the MgAl 2 O 4 -CaO catalyst.

[0042] Optionally, the calcium source is selected from at least one of calcium nitrate, calcium sulfate and calcium hydroxide.

[0043] Optionally, the solvent is selected from water and / or ethanol.

[0044] Optionally, the stirring temperature of II is 60° C. to 80° C., and the stirring time of II is 5 to 10 hours.

[0045] Optionally, the temperature of the stirring II is independently selected from any value of 60° C., 70° C., 80° C., or a range between any two of the above values.

[0046] Optionally, the stirring time II is independently selected from any value among 5h, 6h, 7h, 8h, 9h, 10h or a range between any two of the above.

[0047] Optionally, the temperature of the drying II is 100° C. to 120° C., and the time of the drying II is 8 to 12 hours.

[0048] Optionally, the temperature of the drying II is independently selected from any value of 100° C., 110° C., 120° C., or a range between any two of the above values.

[0049] Optionally, the drying time II is independently selected from any value among 8h, 9h, 10h, 11h, 12h or a range between any two of the above.

[0050] Optionally, the temperature of calcination II is 400° C. to 600° C., and the time of calcination II is 4 to 8 hours.

[0051] Optionally, the temperature of the calcination II is independently selected from any value of 400° C., 500° C., 600° C., or a range between any two of the above values.

[0052] Optionally, the calcination time of II is independently selected from any value of 4h, 5h, 6h, 7h, 8h or a range between any two of the above;

[0053] Optionally, in step (3), the KOH / MgAl 2 O 4 The preparation method of -CaO comprises:

[0054] MgAl 2 O 4 -CaO is impregnated with KOH solution, dried III, and calcined III to obtain KOH / MgAl 2 O 4 -CaO.

[0055] Optionally, the MgAl 2 O 4 -The solid-liquid ratio of CaO to KOH solution is 1:20-30 g / ml.

[0056] Optionally, the MgAl 2 O 4 - The solid-to-liquid ratio of CaO to KOH solution is independently selected from any value of 1:20 g / ml, 1:25 g / ml, 1:30 g / ml, or a range between any two of the above values.

[0057] Optionally, the concentration of the KOH solution is 0.1-2M.

[0058] Optionally, the concentration of the KOH solution is independently selected from any value among 0.1M, 0.3M, 0.5M, 0.7M, 0.9M, 1.1M, 1.3M, 1.5M, 1.7M, 2.0M or a range between any two of the above values.

[0059] Optionally, the immersion time is 4 to 24 hours.

[0060] Optionally, the immersion time is independently selected from any value of 4h, 6h, 8h, 10h, 12h, 14h, 16h, 18h, 20h, 22h, 24h or a range between any two of the above.

[0061] Optionally, the temperature of the drying III is 80° C. to 110° C., and the time of the drying III is 2 to 5 hours.

[0062] Optionally, the temperature of the drying III is independently selected from any value of 80°C, 90°C, 100°C, 110°C or a range between any two of the above values.

[0063] Optionally, the drying time of III is independently selected from any value among 2h, 3h, 4h, 5h or a range between any two of the above.

[0064] Optionally, the temperature of calcining III is 400° C. to 600° C., and the time of calcining III is 3 to 6 hours.

[0065] Optionally, the temperature of the calcination III is independently selected from any value of 400° C., 500° C., 600° C., or a range between any two of the above values.

[0066] Optionally, the calcination time of III is independently selected from any value among 3h, 4h, 5h, 6h or a range between any two of the above.

[0067] Optionally, the amount of the solid composite catalyst used is 0.02 to 1.5 wt % of the weight of the raw material.

[0068] Optionally, the amount of the solid composite catalyst used is independently selected from any value among 0.02wt%, 0.08wt%, 0.14wt%, 0.2wt%, 0.3wt%, 0.6wt%, 0.9wt%, 1.2, 1.5wt% or a range between any two of the above based on the weight of the raw material.

[0069] Optionally, the mass ratio of the ethylene oxide to the diethylene glycol is 1:1-4.

[0070] Optionally, the mass ratio of the ethylene oxide to the diethylene glycol is independently selected from any value of 1:1, 1:2, 1:3, 1:4 or a range between any two of the above.

[0071] Optionally, the reaction temperature is 90-220°C.

[0072] Optionally, the reaction temperature is independently selected from any value of 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 220°C or a range between any two of the above.

[0073] Optionally, the reaction pressure is 0.2-0.5 MPa.

[0074] Optionally, the reaction pressure is independently selected from any value among 0.2Mpa, 0.3Mpa, 0.4Mpa, 0.5Mpa or a range between any two of the above values.

[0075] The distillation purification process is to transfer the triethylene glycol and tetraethylene glycol mixture obtained by the reaction into a distillation tower, and by setting different vacuum distillation conditions, the residual diethylene glycol, the prepared triethylene glycol and tetraethylene glycol can be obtained respectively. Preferably, diethylene glycol is distilled at 104°C / 0.66KPa (170°C at the bottom of the kettle); preferably, triethylene glycol is distilled at 120°C / 0.66KPa (180°C at the bottom of the kettle); preferably, tetraethylene glycol is distilled at 145°C / 0.66kPa (200°C at the bottom of the kettle).

[0076] The distillation process uses nitrogen protection, and the tail gas is discharged after being absorbed by water.

[0077] The beneficial effects of this application include:

[0078] 1) The catalyst provided in the present application can be used in the preparation of triethylene glycol and tetraethylene glycol by the contact reaction of diethylene glycol and ethylene oxide with the catalyst, and the yield of triethylene glycol and tetraethylene glycol can be increased.

[0079] 2) The preparation method of the catalyst provided in this application is stable, controllable and reproducible.

[0080] 3) The method for preparing triethylene glycol and tetraethylene glycol by reaction provided in the present application uses the catalyst provided in the present application, has a fast reaction speed and a high yield, and can be applied to large-scale production. DETAILED DESCRIPTION

[0081] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0082] Unless otherwise specified, the raw materials in the examples of this application were purchased through commercial channels.

[0083] The gas chromatograph is a 7890B gas chromatograph from Agilent.

[0084] The product yield in the examples of this application is calculated as follows:

[0085] The product yield calculation formula in the examples of the present application is as follows:

[0086] Triethylene glycol yield: y(triethylene glycol) = (B / 150) / (A / 44)*100%

[0087] Yield of triethylene glycol + tetraethylene glycol: y (total) = [(B / 150) + (2C / 194)] / (A / 44) * 100%

[0088] In the above product yield calculation formula:

[0089] A is the weight % of ethylene oxide

[0090] B is the weight % of triethylene glycol in the product

[0091] C is the weight % of tetraethylene glycol in the product.

[0092] Example 1

[0093] Taking No. 1 in Tables 1 to 3 as an example, weigh magnesium nitrate hexahydrate (Mg(NO 3 ) 2 6H 2 O), aluminum nitrate nonahydrate (Al(NO 3 ) 3 9H 2 O) (the molar ratio of magnesium to aluminum is 1:2), sodium hydroxide (NaOH) (the molar ratio of sodium hydroxide to the total amount of magnesium and aluminum is 1.5:1) and anhydrous sodium carbonate (Na 2 CO 3 ) (the molar ratio of sodium carbonate to the total amount of magnesium and aluminum is 0.8:1) was dissolved in deionized water. Stirred at room temperature for 11 hours; the obtained suspension was transferred to a 500 ml hydrothermal kettle and hydrothermally reacted at 120°C for 24 hours; the obtained solid was filtered and washed with deionized water until the filtrate was neutral; then placed in a 60°C oven for drying for 112 hours; the solid was placed in a crucible and calcined at 1200°C in a static air atmosphere for 14 hours to obtain MgAl 2 O 4 Calcium nitrate and prepared MgAl 2 O 4 (CaO and MgAl 2 O 4 The mass ratio is 0.5:1) stirred in water at 80℃ for 5h, dried in an oven at 100℃ for 9h, and finally calcined in a muffle furnace at 500℃ for 4h to obtain MgAl 2 O 4 -CaO. The prepared MgAl 2 O 4-CaO was immersed in a 0.5M KOH solution for 12 h, filtered, dried in an oven at 100 °C for 5 h, and calcined at 500 °C for 4 h to obtain KOH / MgAl 2 O 4 -CaO, denoted as catalyst 1 # .

[0094] Table 1

[0095]

[0096]

[0097] Table 2

[0098]

[0099]

[0100] The columns of Table 1 and Table 2 above are explained as follows:

[0101] Calcium sources: calcium nitrate (Ca1), calcium sulfate (Ca2), calcium hydroxide (Ca3).

[0102] Solvent: water (solvent 1), ethanol (solvent 2), water and ethanol (solvent 3), wherein the volume ratio of water:ethanol is 1:1.

[0103] Table 3

[0104]

[0105]

[0106] The columns of Table 3 above are explained as follows:

[0107] Drying III: Preparation of KOH / MgAl 2 O 4 - Drying during the CaO process.

[0108] Calcination III: Preparation of KOH / MgAl 2 O 4 -Calcination during CaO process.

[0109] In Tables 1 to 3, the catalysts corresponding to the preparations of Nos. 1 to 28 are Catalyst 1 # ~Catalyst 28 # .

[0110] Example 2

[0111] Diethylene glycol and a catalyst are added to a dry pressure reactor, and the reactor is sealed; the air in the reactor is replaced with nitrogen for 3 times, and stirring is started; the temperature is raised to 100° C., and ethylene oxide is slowly added to carry out a copolymerization reaction; wherein, the reaction pressure is maintained at 0.3 MPa and the reaction temperature is maintained at 140° C. by controlling the addition rate of ethylene oxide for 3 hours; after the ethylene oxide is completely introduced, the mixture is aged at 140° C. for 30 minutes and degassed for 50 minutes to obtain a colorless and transparent mixed solution of triethylene glycol and tetraethylene glycol, and the content (weight percentage) of each component is analyzed by gas chromatography.

[0112] The catalyst 1 prepared in Example 1 was used # 、Catalyst 5 # 、Catalyst 10 # 、Catalyst 16 # 、Catalyst 20 # 、Catalyst 24 # 、Catalyst 28 # The reaction of preparing triethylene glycol and tetraethylene glycol was carried out, and each reaction parameter was changed. The reaction raw materials and products were analyzed by gas chromatography. The composition of the reaction product was analyzed using Agilent 7890B gas chromatograph (FID detector, FFAP capillary column). The reaction results are shown in Table 4.

[0113] Comparative Example 1

[0114] Add diethylene glycol, KOH / MgAl into the dry pressure reactor. 2 O 4 Catalyst, sealed reactor; replaced the air in the reactor with nitrogen 3 times, started stirring; heated to 100 ° C, slowly added ethylene oxide for copolymerization; wherein, the reaction pressure was kept at 0.3MPa by controlling the addition rate of ethylene oxide, and the reaction temperature was kept at 140 ° C for 3 hours; after the ethylene oxide was completely introduced, it was aged at 140 ° C for 30 minutes and degassed for 50 minutes to obtain a colorless and transparent mixture of triethylene glycol and tetraethylene glycol, and the content of each component (weight percentage) was analyzed by gas chromatography. The composition of the reaction product was analyzed using an Agilent 7890B gas chromatograph (FID detector, FFAP capillary column). The reaction results are shown in Table 4.

[0115] Table 4

[0116]

[0117]

[0118] Transfer the mixed liquid of triethylene glycol and tetraethylene glycol into a distillation tower, heat and raise the temperature, and distill diethylene glycol under reduced pressure at 104°C / 0.66KPa (170°C at the bottom of the kettle); repeat the above operation and distill triethylene glycol at 120°C / 0.66KPa (180°C at the bottom of the kettle); repeat the above operation and distill tetraethylene glycol at 145°C / 0.66KPa (200°C at the bottom of the kettle).

[0119] When using this process, nitrogen protection is used during distillation, and the tail gas is discharged after being absorbed by water.

[0120] The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for preparing ether using a solid base catalyst, It is characterized in that The method comprises: The raw material containing diethylene glycol and ethylene oxide is contacted with a solid composite catalyst to react to obtain triethylene glycol and tetraethylene glycol; The solid composite catalyst is KOH / MgAl 2 O 4 -CaO.

2. The method according to claim 1, It is characterized in that The KOH / MgAl 2 O 4 The preparation method of -CaO comprises the following steps: (1) MgAl was prepared by hydrothermal method 2 O 4 ; (2) Excessive impregnation of CaO on MgAl 2 O 4 Surface, MgAl 2 O 4 -CaO; (3) Impregnation of MgAl with KOH solution 2 O 4 -CaO, to obtain KOH / MgAl 2 O 4 -CaO; Preferably, the KOH / MgAl 2 O 4 -CaO, CaO and MgAl 2 O 4 The mass ratio is 0.1~2.5:

1.

3. The method according to claim 2, It is characterized in that In the step (1), the MgAl 2 O 4 The preparation method comprises: A mixture containing magnesium nitrate, aluminum nitrate, sodium hydroxide and sodium carbonate is subjected to hydrothermal reaction, dried and calcined to obtain the MgAl 2 O 4 .

4. The method according to claim 3, It is characterized in that The molar ratio of the magnesium nitrate to the aluminum nitrate is (0.9-1):2, The molar amount of the magnesium nitrate is calculated based on the molar amount of the magnesium element, and the molar amount of the aluminum nitrate is calculated based on the molar amount of the aluminum element; Preferably, the molar ratio of the sodium hydroxide to the total amount of the magnesium element and the aluminum element is (1.5-2.5):1; Preferably, the molar ratio of the sodium carbonate to the total amount of the magnesium element and the aluminum element is (0.4-1.7):1; Preferably, the temperature of the hydrothermal reaction is 110-130° C., and the time of the hydrothermal reaction is 16-24 h; Preferably, the temperature of the drying I is 50 to 80° C., and the drying I time is 12 to 24 hours; Preferably, the temperature of the calcination I is 500-1300° C., and the time of the calcination I is 2-4 hours.

5. The method according to claim 2, It is characterized in that In the step (2), the MgAl 2 O 4 The preparation method of -CaO comprises: Containing calcium source, MgAl 2 O 4 , a mixture of solvents II, stirring II, drying II, calcining II, to obtain the MgAl 2 O 4 -CaO catalyst.

6. The method according to claim 5, It is characterized in that The calcium source is selected from at least one of calcium nitrate, calcium sulfate and calcium hydroxide; Preferably, the solvent is selected from water and / or ethanol; Preferably, the stirring temperature of II is 60°C to 80°C, and the stirring time of II is 5 to 10 hours; Preferably, the temperature of drying II is 100°C to 120°C, and the time of drying II is 8 to 12 hours; Preferably, the temperature of the calcination II is 400° C. to 600° C., and the time of the calcination II is 4 to 8 hours.

7. The method according to claim 2, It is characterized in that In the step (3), the KOH / MgAl 2 O 4 The preparation method of -CaO comprises: MgAl 2 O 4 -CaO is impregnated with KOH solution, dried III, and calcined III to obtain KOH / MgAl 2 O 4 -CaO.

8. The method according to claim 7, It is characterized in that The MgAl 2 O 4 -The solid-liquid ratio of CaO to KOH solution is 1:20-30 g / ml; Preferably, the concentration of the KOH solution is 0.1 to 2 M; Preferably, the immersion time is 4 to 24 hours; Preferably, the temperature of drying III is 80°C to 110°C, and the time of drying III is 2 to 5 hours; Preferably, the temperature of calcining III is 400° C. to 600° C., and the time of calcining III is 3 to 6 hours.

9. The method according to claim 1, It is characterized in that The amount of the solid composite catalyst is 0.02-1.5 wt% of the weight of the raw material; Preferably, the mass ratio of the ethylene oxide to the diethylene glycol is 1:1-4.

10. The method according to claim 1, It is characterized in that The reaction temperature is 90-220°C; Preferably, the reaction pressure is 0.2-0.5 MPa.

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