A method for preparing p-dioxanone by liquid phase dehydrogenation of diethylene glycol

Abstract

The application discloses a method for preparing p-dioxycyclohexanone by liquid-phase dehydrogenation of diethylene glycol, and belongs to the technical field of organic catalytic synthesis. The catalyst is loaded in a fixed bed reactor, liquid-phase diethylene glycol is introduced, the liquid diethylene glycol is contacted with the catalyst, the liquid space velocity of the diethylene glycol is 0.1-3 g / hour.g catalyst, and p-dioxycyclohexanone is prepared under the conditions that the reaction temperature is 170-240 DEG C, and the reaction pressure is 1-5 atmospheres; the catalyst comprises Cu x M’ (6‑x) M”2O9, wherein x=0.2-6, the M' is at least one of Mn, Zn, Mg, Co, Ni, and the M'' is at least one of Fe, Al, La, Ce and Pr. The application adopts liquid-phase reaction, does not need heating vaporization, can reduce energy consumption, the contact between the catalyst and the liquid diethylene glycol is more sufficient, the liquid-phase dehydrogenation reaction efficiency is higher, only needs to adopt a fixed bed, the device is simple, the cost is low, and the application is more green, energy-saving and low-cost as a whole, and has high industrial application value.

Description

Technical Field

[0001] This invention belongs to the field of organic catalytic synthesis technology, and more specifically, relates to a method for preparing p-dioxanone by liquid-phase dehydrogenation of diethylene glycol. Background Technology

[0002] p-Dioxane (PDO) is the monomer for synthesizing poly(p-dioxane) ketone (PPDO). PPDO is an aliphatic polyether ester. Compared with other typical aliphatic polyesters, the unique presence of ether bonds in its molecular structure gives it excellent mechanical properties, biocompatibility, and biodegradability. It shows significant potential for application in biodegradable medical implant materials such as absorbable monofilament surgical sutures, exhibiting outstanding advantages such as good toughness and low material memory, making it suitable for all types of soft tissue. Furthermore, it possesses the characteristic of being fully recyclable in a closed-loop system.

[0003] Traditional PDO production processes utilize organic synthesis methods with 2,3-dichloro-1,4-dioxane as a raw material. These methods suffer from low reaction selectivity, high pollution levels, and poor industrial feasibility. Catalytic carbonylation synthesis of PDO using ethylene glycol as a raw material generates large amounts of salt, incurs high catalyst costs, requires stringent reaction conditions, and also suffers from low industrial feasibility.

[0004] The one-step dehydrogenation of diethylene glycol to produce PDO is a simple and feasible reaction. The specific process involves using gas to carry diethylene glycol into a vaporization chamber for heating and vaporization. Under near-atmospheric pressure and at a temperature maintained between 240 and 360°C, PDO is produced via a dehydrogenation catalyst. Chinese patent CN1325162C discloses a gas-phase dehydrogenation catalyst for diethylene glycol, but this process has the following problems: 1) Using hydrogen to carry diethylene glycol into the vaporization chamber for heating and vaporization results in high energy consumption; 2) Hydrogen requires a hydrogen pressurization device for recycling, further increasing energy consumption; 3) Hydrogen generally requires a methanation device to remove hydrogen-rich CO, as CO causes copper catalyst sintering; 4) Most of the purified hydrogen is recycled and cannot be sold as a product. Overall, the gas-phase dehydrogenation process is energy-intensive and relatively costly. Therefore, there is an urgent need to develop a cost-effective and efficient method for preparing p-dioxanone. Summary of the Invention

[0005] In order to overcome the shortcomings and deficiencies of the existing technology, the purpose of this invention is to provide a method for preparing p-dioxanone by liquid-phase dehydrogenation of diethylene glycol.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] This invention provides a method for preparing p-dioxanone by liquid-phase dehydrogenation of diethylene glycol, comprising the following steps: loading a catalyst into a fixed-bed reactor, introducing liquid diethylene glycol to contact the catalyst, wherein the liquid hourly space velocity of the diethylene glycol is 0.1–3 g / h·g catalyst, and preparing p-dioxanone under reaction conditions of 170–240°C and 1–5 atm; wherein the catalyst composition is Cu. x M' (6-x) M”2O9, where x = 0.2-6, M' is at least one of Mn, Zn, Mg, Co, and Ni, and M” is at least one of Fe, Al, La, Ce, and Pr.

[0008] Based on the above technical solution, further, the liquid hourly space velocity of the diethylene glycol is 0.3 to 1.2 g / h·g catalyst, preferably 0.3 to 0.9 g / h·g catalyst.

[0009] Based on the above technical solution, the reaction temperature is further specified as 160–250℃, preferably 200–230℃.

[0010] Based on the above technical solution, the reaction pressure is further specified as 1 to 3 atmospheres, preferably 1 to 1.5 atmospheres.

[0011] Based on the above technical solution, further, x = 3-4.

[0012] Based on the above technical solution, the catalyst is further prepared by: firstly, a precursor with a hydrotalcite structure is prepared by co-precipitation, the composition of which is: Cu x M' (6-x) M”2(OH) 16 (CO3)H2O, where x = 0.2 to 6, is used to prepare a catalyst by calcination and hydrogen reduction.

[0013] Based on the above technical solution, the preparation method of the catalyst further includes the following steps:

[0014] 1) Prepare an aqueous solution A containing copper salt, M' metal salt and M” metal salt, and prepare an aqueous solution B containing sodium hydroxide and sodium carbonate;

[0015] 2) While stirring continuously and keeping the temperature at 50-80℃, add solution B dropwise to solution A until the pH reaches 9.5-10.5, and then age for 12-36 hours.

[0016] 3) Filter the reaction solution obtained in step 2), and wash the resulting filter cake with water until the pH is 6-8;

[0017] 4) The washed filter cake is dried at 60-120℃ to obtain a precursor with a hydrotalcite structure;

[0018] 5) The precursor with the hydrotalcite structure obtained in step 4) is calcined in air at 400-600°C for 1-10 hours, and then reduced at 200-400°C for 1-6 hours to obtain the catalyst.

[0019] Based on the above technical solution, further, in step 1), the copper salt, M' metal salt and M” metal salt are at least one of the nitrate, acetate, sulfate, chloride and hydrate of copper, M' metal and M” metal respectively.

[0020] Based on the above technical solution, further, in step 1), solution A contains (Cu) 2+ The molar concentration ratio of +M') / M” is 1:1 to 4:1.

[0021] Based on the above technical solution, further, in step 1), the concentration of sodium hydroxide in aqueous solution B is 0.1-1.0 mol / L, the concentration of sodium carbonate is 0.001-0.1 mol / L, and the molar ratio of sodium hydroxide to sodium carbonate is 20:1-10:1.

[0022] Based on the above technical solution, further, in step 5), the calcination temperature is 450-550℃, the calcination time is 3-7 hours, the reduction temperature is 250-350℃, and the reduction time is 1-4 hours.

[0023] Based on the above technical solution, further, in step 5), the reducing atmosphere is hydrogen or a mixture of hydrogen and an inert gas, the volume percentage of hydrogen is 20-100%, and the inert gas is one of nitrogen, argon, and helium.

[0024] Compared with existing diethylene glycol gas-phase dehydrogenation techniques for the preparation of dioxane, this invention has the following advantages:

[0025] 1. This invention employs a liquid-phase reaction, resulting in more thorough contact between the catalyst and liquid diethylene glycol, leading to higher efficiency in the liquid-phase dehydrogenation reaction;

[0026] 2. In the process of preparing p-dioxanone by liquid-phase dehydrogenation of diethylene glycol in this invention, diethylene glycol is in a liquid phase and does not require heating and vaporization, which can reduce energy consumption;

[0027] 3. The hydrogen produced in the diethylene glycol liquid-phase dehydrogenation process to prepare dioxane does not require further purification by methanation or further pressurization, because the hydrogen does not participate in the recycling process, which can save on equipment costs and reduce energy consumption.

[0028] 4. The diethylene glycol liquid-phase dehydrogenation preparation of dioxane can be carried out using only a fixed bed, which is simple and low in cost. Detailed Implementation

[0029] The present invention will be described in detail below with reference to the embodiments. However, the implementation of the present invention is not limited thereto. Obviously, the embodiments described below are only some embodiments of the present invention. For those skilled in the art, other similar embodiments can be obtained without creative effort and all fall within the protection scope of the present invention.

[0030] Example 1

[0031] Preparation of the catalyst Cu₂Zn₄Al₂O₉: 50 mL of aqueous solution A containing 0.01 mol copper nitrate trihydrate, 0.02 mol zinc nitrate hexahydrate, and 0.01 mol aluminum nitrate nonahydrate, and aqueous solution B containing 0.16 mol / L sodium hydroxide and 0.01 mol / L sodium carbonate were prepared. Under continuous stirring and at a reaction temperature of 60 °C, solution B was added dropwise to solution A until the pH reached 10, and the mixture was aged at 60 °C for 24 h. The solution was filtered with deionized water and washed until the pH of the filtrate reached 7. The filter cake was dried at 100 °C for 12 h to obtain a catalyst precursor with a hydrotalcite structure. The precursor was calcined at 500 °C for 5 h in an air atmosphere, and then reduced with >99.9% hydrogen at 300 °C for 2 h to obtain the catalyst. The catalyst was pressed into tablets under a pressure of 10 MPa, and the 20–40 mesh particles were used in a fixed-bed reactor.

[0032] Example 2

[0033] Preparation of catalyst Cu3Zn3Al2O9: Prepare 50 mL of aqueous solution A containing 0.015 mol copper nitrate trihydrate, 0.015 mol zinc nitrate hexahydrate, and 0.01 mol aluminum nitrate nonahydrate. The remaining steps are the same as in Example 1.

[0034] Example 3

[0035] Preparation of catalyst Cu4Zn2Al2O9: Prepare 50 mL of aqueous solution A containing 0.02 mol copper nitrate trihydrate, 0.01 mol zinc nitrate hexahydrate, and 0.01 mol aluminum nitrate nonahydrate. The remaining steps are the same as in Example 1.

[0036] Example 4

[0037] A reaction tube with an inner diameter of 10 mm was used, containing 5 g of the Cu2Zn4Al2O9 catalyst prepared in Example 1. Both ends were sealed with quartz sand. The reaction pressure was 1.5 atm, the reaction temperature was 200 °C, and the liquid hourly space velocity (LHSV) of diethylene glycol was 1.2 g / h·g catalyst. The reaction proceeded to produce p-dioxanone. After the reaction started and stabilized for 2 h, the reactants were collected and analyzed by gas chromatography. The results are shown in Table 1.

[0038] Example 5

[0039] A reaction tube with an inner diameter of 10 mm was used, containing 5 g of the Cu3Zn3Al2O9 catalyst prepared in Example 2. Both ends were sealed with quartz sand. The reaction pressure was 1.5 atm, the reaction temperature was 200 °C, and the liquid hourly space velocity (LHSV) of diethylene glycol was 1.2 g / h·g catalyst. The reaction proceeded to produce p-dioxanone. After the reaction started and stabilized for 2 h, the reactants were collected and analyzed by gas chromatography. The results are shown in Table 1.

[0040] Example 6

[0041] A reaction tube with an inner diameter of 10 mm was used, containing 5 g of the Cu4Zn2Al2O9 catalyst prepared in Example 3. Both ends were sealed with quartz sand. The reaction pressure was 1.5 atm, the reaction temperature was 200 °C, and the liquid hourly space velocity (LHSV) of diethylene glycol was 1.2 g / h·g catalyst. The reaction proceeded to produce p-dioxanone. After the reaction started and stabilized for 2 h, the reactants were collected and analyzed by gas chromatography. The results are shown in Table 1.

[0042] Example 7

[0043] A reaction tube with an inner diameter of 10 mm was used, containing 5 g of the Cu3Zn3Al2O9 catalyst prepared in Example 2. Both ends were sealed with quartz sand. The reaction pressure was 3 atmospheres, the reaction temperature was 200℃, and the liquid hourly space velocity (LHSV) of diethylene glycol was 1.2 g / h·g catalyst. The reaction proceeded to produce p-dioxanone. After the reaction started and stabilized for 2 h, the reactants were collected and analyzed by gas chromatography. The results are shown in Table 1.

[0044] Example 8

[0045] A reaction tube with an inner diameter of 10 mm was used, containing 5 g of the Cu3Zn3Al2O9 catalyst prepared in Example 2. Both ends were sealed with quartz sand. The reaction pressure was 10 atmospheres, the reaction temperature was 200 °C, and the liquid hourly space velocity (LHSV) of diethylene glycol was 1.2 g / h·g catalyst. The reaction proceeded to produce p-dioxanone. After the reaction started and stabilized for 2 h, the reactants were collected and analyzed by gas chromatography. The results are shown in Table 1.

[0046] Example 9

[0047] A reaction tube with an inner diameter of 10 mm was used, containing 5 g of the Cu3Zn3Al2O9 catalyst prepared in Example 2. Both ends were sealed with quartz sand. The reaction pressure was 1.5 atm, the reaction temperature was 160 °C, and the liquid hourly space velocity (LHSV) of diethylene glycol was 1.2 g / h·g catalyst. The reaction proceeded to produce p-dioxanone. After the reaction started and stabilized for 2 h, the reactants were collected and analyzed by gas chromatography. The results are shown in Table 1.

[0048] Example 10

[0049] A reaction tube with an inner diameter of 10 mm was used, containing 5 g of the Cu3Zn3Al2O9 catalyst prepared in Example 2. Both ends were sealed with quartz sand. The reaction pressure was 1.5 atm, the reaction temperature was 220 °C, and the liquid hourly space velocity (LHSV) of diethylene glycol was 1.2 g / h·g catalyst. The reaction proceeded to produce p-dioxanone. After the reaction started and stabilized for 2 h, the reactants were collected and analyzed by gas chromatography. The results are shown in Table 1.

[0050] Example 11

[0051] A reaction tube with an inner diameter of 10 mm was used, containing 5 g of the Cu3Zn3Al2O9 catalyst prepared in Example 2. Both ends were sealed with quartz sand. The reaction pressure was 1.5 atm, the reaction temperature was 250 °C, and the liquid hourly space velocity (LHSV) of diethylene glycol was 1.2 g / h·g catalyst. The reaction proceeded to produce p-dioxanone. After the reaction started and stabilized for 2 h, the reactants were collected and analyzed by gas chromatography. The results are shown in Table 1.

[0052] Example 12

[0053] A reaction tube with an inner diameter of 10 mm was used, containing 5 g of the Cu3Zn3Al2O9 catalyst prepared in Example 2. Both ends were sealed with quartz sand. The reaction pressure was 1.5 atm, the reaction temperature was 200 °C, and the liquid hourly space velocity (LHSV) of diethylene glycol was 0.3 g / h·g catalyst. The reaction proceeded to produce p-dioxanone. After the reaction started and stabilized for 2 h, the reactants were collected and analyzed by gas chromatography. The results are shown in Table 1.

[0054] Example 13

[0055] A reaction tube with an inner diameter of 10 mm was used, containing 5 g of the Cu3Zn3Al2O9 catalyst prepared in Example 2. Both ends were sealed with quartz sand. The reaction pressure was 1.5 atm, the reaction temperature was 200 °C, and the liquid hourly space velocity (LHSV) of diethylene glycol was 0.9 g / h·g catalyst. The reaction proceeded to produce p-dioxanone. After the reaction started and stabilized for 2 h, the reactants were collected and analyzed by gas chromatography. The results are shown in Table 1.

[0056] Example 14

[0057] A reaction tube with an inner diameter of 10 mm was used, containing 5 g of the Cu3Zn3Al2O9 catalyst prepared in Example 2. Both ends were sealed with quartz sand. The reaction pressure was 1.5 atm, the reaction temperature was 200 °C, and the liquid hourly space velocity (LHSV) of diethylene glycol was 2.4 g / h·g catalyst. The reaction proceeded to produce p-dioxanone. After the reaction started and stabilized for 2 h, the reactants were collected and analyzed by gas chromatography. The results are shown in Table 1.

[0058] Example 15

[0059] A reaction tube with an inner diameter of 10 mm was used, containing 5 g of the Cu3Zn3Al2O9 catalyst prepared in Example 2. Both ends were sealed with quartz sand. The reaction pressure was 1.5 atm, the reaction temperature was 200 °C, and the liquid hourly space velocity (LHSV) of diethylene glycol was 4.8 g / h·g catalyst. The reaction proceeded to produce p-dioxanone. After the reaction started and stabilized for 2 h, the reactants were collected and analyzed by gas chromatography. The results are shown in Table 1.

[0060] Example 16

[0061] A reaction tube with an inner diameter of 10 mm was used, containing 5 g of the Cu3Zn3Al2O9 catalyst prepared in Example 2. Both ends were sealed with quartz sand. The reaction pressure was 1.5 atm, the reaction temperature was 200 °C, and the liquid hourly space velocity (LISH) of diethylene glycol was 1.2 g / h·g catalyst. The reaction was carried out and stabilized for 300 h. The liquid phase product was collected and analyzed by gas chromatography. The results are shown in Table 1. Analysis of the gas phase product revealed only hydrogen gas and no carbon monoxide.

[0062] Table 1. Different copper-supported catalysts, reaction conditions, and results

[0063]

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing p-dioxanone by liquid-phase dehydrogenation of diethylene glycol, characterized in that, The process includes the following steps: A catalyst is loaded into a fixed-bed reactor, and liquid diethylene glycol is introduced to bring the diethylene glycol into contact with the catalyst. The liquid hourly space velocity (LHSV) of the diethylene glycol is 0.3–1.2 g / h•g catalyst. p-Dioxane is prepared under reaction conditions of 200–230 °C and 1–1.5 atm. The catalyst composition is Cu. x M' (6-x) M''2O9, where x=3, M' is Zn, and M'' is Al.

2. The method according to claim 1, characterized in that, The liquid hourly space velocity of the diethylene glycol is 0.3~0.9 g / h•g catalyst.

3. The method according to claim 1, characterized in that, The catalyst is prepared by: firstly, a precursor with a hydrotalcite structure is prepared by co-precipitation, the composition of which is: Cu x M' (6-x) M''2(OH) 16 (CO3)H2O, where x=3, is used to prepare a catalyst by calcination and hydrogen reduction, wherein M' is Zn and M'' is Al.

4. The method according to claim 3, characterized in that, The preparation method of the catalyst includes the following steps: 1) Prepare an aqueous solution A containing copper salt, M' metal salt and M'' metal salt, and prepare an aqueous solution B containing sodium hydroxide and sodium carbonate, wherein M' is Zn and M'' is Al; 2) While stirring continuously, keep the temperature at 50~80℃, add solution B dropwise to solution A until the pH reaches 9.5~10.5, and then age for 12~36 hours; 3) Filter the reaction solution obtained in step 2), and wash the resulting filter cake with water until the pH is 6-8; 4) The washed filter cake is dried at 60~120℃ to obtain a precursor with a hydrotalcite structure; 5) The precursor with the hydrotalcite structure obtained in step 4) is calcined in air at 400~600℃ for 1~10 hours, and then reduced at 200~400℃ for 1~6 hours to obtain the catalyst.

5. The method according to claim 4, characterized in that, In step 1), the copper salt, M' metal salt, and M'' metal salt are at least one of the following: nitrate, acetate, sulfate, chloride, and hydrate of copper, M' metal, and M'' metal, respectively; in solution A (Cu 2+ The molar concentration ratio of (+ M') / M'' is 1:1 to 4:1, where M' is Zn and M'' is Al.

6. The method according to claim 4, characterized in that, In step 1), the concentration of sodium hydroxide in aqueous solution B is 0.1~1.0 mol / L, the concentration of sodium carbonate is 0.001~0.1 mol / L, and the molar ratio of sodium hydroxide to sodium carbonate is 20:1~10:1.

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