Dehydrogenation catalyst, method for preparing and using the same, and method for preparing p-dioxanone from diethylene glycol

Abstract

The present application relates to the field of catalyst technology, and provides a dehydrogenation catalyst, a preparation method and application thereof, and a method for preparing p-dioxanone by dehydrogenating diethylene glycol, wherein the dehydrogenation catalyst comprises 3-15 wt% of active metal oxide and 85-97 wt% of carrier based on the mass of the catalyst; the active metal oxide comprises CuO, and the carrier comprises SiO2; and the particle size of the metal active component of the reduced catalyst is 0.5-3 nm. The dehydrogenation catalyst provided by the present application has the characteristics of low content and good dispersity of metal active component, low surface acid content, good stability and long service life. When the dehydrogenation catalyst is applied to the reaction of preparing p-dioxanone by dehydrogenating diethylene glycol, the catalyst has the characteristics of high utilization rate of active component, can obviously inhibit the occurrence of side reactions, and significantly improves the selectivity of the target product; the application process condition is easy to realize, and can greatly reduce the production cost of p-dioxanone.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, and more specifically, to a dehydrogenation catalyst, its preparation method and application, and a method for the dehydrogenation of diethylene glycol to produce p-dioxanone. Background Technology

[0002] Aliphatic polyester poly(p-dioxanone) (PPDO) possesses excellent biocompatibility, bioabsorbability, and biodegradability due to the abundant ether and ester bonds in its molecular chain. Its monomer and derivatives are widely used in biomedical materials such as surgical sutures, bone plates, and tissue repair. PPDO is primarily obtained through the ring-opening polymerization of p-dioxanone (PDO). To prepare high-performance PPDO, high-purity PDO monomers must first be obtained. However, to date, due to difficult synthesis conditions and high preparation costs, PDO is not a readily available commercial product, thus hindering its further widespread application. Among the limited reports on PDO synthesis, the most economical and convenient route is the direct synthesis of PDO via catalytic dehydrogenation cyclization using inexpensive and readily available diethylene glycol as a raw material, under the action of a dehydrogenation catalyst. The dehydrogenation catalyst used mainly consists of alumina, silica, and molecular sieves as supports, along with transition metals such as copper, silver, platinum, and zinc supported on the supports. In this approach, finding a dehydrogenation catalyst with high activity, good selectivity, and excellent stability is key to the low-cost synthesis of high-purity PDO.

[0003] CN112473675A discloses a catalyst and method for preparing p-dioxanone. This catalyst contains 46.2–46.9% copper oxide, 0.1–1% sodium oxide, and the balance is silicon dioxide. It can be used for the preparation of p-dioxanone; however, this catalyst has a high content of active components, strong surface basicity, and numerous side reactions. CN1739852A discloses a catalyst for the gas-phase dehydrogenation of diethylene glycol to PDO. This catalyst is prepared by a co-precipitation method, with the main component being a copper-zinc compound supported on an inert support. It exhibits good conversion and selectivity, but requires a high content of active components, ranging from 20% to 90%. CN112724122A discloses a supported dehydrogenation catalyst using hydroxyapatite as a support. The active component is a Group VIII or Group IB transition metal. The catalyst has good thermal stability and good recyclability. However, this catalyst requires a high-pressure reactor to dehydrogenate diethylene glycol to PDO in the presence of oxygen and solvent. The operating conditions are quite harsh, and the reaction and separation processes are complex, which is not conducive to large-scale production.

[0004] Existing catalysts for the dehydrogenation of diethylene glycol to p-dioxanone all suffer from problems to varying degrees, including high active component content, low utilization rate, poor catalyst performance, and demanding process conditions. Therefore, there is an urgent need to develop a catalyst for the dehydrogenation of diethylene glycol to p-dioxanone with low active component content, good catalytic performance, and less demanding process conditions. Summary of the Invention

[0005] The purpose of this invention is to provide a dehydrogenation catalyst and its preparation method, so as to solve the technical problems of existing catalysts for the dehydrogenation of diethylene glycol to p-dioxanone, which have high active component content, poor catalyst performance, and harsh process conditions.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] In a first aspect, the present invention provides a dehydrogenation catalyst, comprising, based on catalyst mass, 3-15 wt% of an active metal oxide and 85-97 wt% of a support; the active metal oxide comprises CuO, and the support comprises SiO2; the particle size of the metal active component after reduction of the catalyst is 0.5-3 nm.

[0008] The dehydrogenation catalyst provided by the present invention has a low content of CuO, which is only 3 to 15 wt% in the catalyst; and the reduced metal active component has small particle size, high dispersion and uniform distribution.

[0009] According to some embodiments of the present invention, the catalyst is reduced Cu + / (Cu 0 +Cu + The proportion is 35%–70%.

[0010] According to some embodiments of the present invention, the catalyst is reduced Cu + / (Cu 0 +Cu + The proportion is 40-65%.

[0011] According to some embodiments of the present invention, the surface acidity of the catalyst is 0.01 to 0.05 mmol / g.

[0012] The most significant side reaction in the dehydrogenation of diethylene glycol to dioxane is the dehydration of the feedstock to form dioxane. The dehydrogenation catalyst provided by this invention has a low surface acidity, which can effectively suppress the occurrence of this side reaction and improve the selectivity of the target product.

[0013] According to some embodiments of the present invention, the catalyst has a specific surface area of ​​250–450 m². 2 / g.

[0014] According to some embodiments of the present invention, the catalyst has a specific surface area of ​​300–440 m². 2 / g.

[0015] According to some embodiments of the present invention, the catalyst has a specific surface area of ​​350–430 m². 2 / g.

[0016] In a second aspect, the present invention provides a method for preparing the catalyst described in the first aspect, comprising: obtaining a mixed solution comprising a copper-containing precursor and an organoamine siloxane; adding ammonia water to the mixed solution and stirring; adding a silicon source to the mixed solution and heating and stirring; then adding an alcohol component dropwise to the mixed solution, followed by solid-liquid separation, collecting the solid component, washing, drying, and calcining to obtain the catalyst.

[0017] The dehydrogenation catalyst preparation method provided by this invention restricts the aggregation of the metal active component during the synthesis process by coating a copper-containing precursor with an organoamine siloxane. The monodisperse metal active component reacts with the hydroxyl groups on the silicon source surface via the organoamine terminal, grafting the metal active component onto the support surface to obtain uniform monodisperse active sites. This results in a high degree of dispersion of the metal active component, making it less prone to particle size enlargement upon heating, thus giving the catalyst excellent thermal stability and contributing to a long catalyst lifespan. Furthermore, the number of hydroxyl groups on the catalyst surface is reduced through the reaction with the organoamine, lowering the surface acidity of the catalyst.

[0018] According to some embodiments of the present invention, the copper-containing precursor is selected from at least one of copper nitrate, copper sulfate, copper acetate, and copper chloride.

[0019] According to some embodiments of the present invention, the organoamine siloxane is selected from at least one of (3-aminopropyl)triethoxysilane, (3-aminopropyl)trimethoxysilane, and (2-aminoethyl)triethoxysilane.

[0020] According to some embodiments of the present invention, the concentration of the ammonia water is 5-28 wt%.

[0021] According to some embodiments of the present invention, the silicon source is selected from at least one of tetraethyl silicate (TEOS), silica sol, sodium silicate, and amorphous silicon oxide.

[0022] According to some embodiments of the present invention, the alcohol component is selected from at least one of methanol, ethanol, and isopropanol.

[0023] According to some embodiments of the present invention, the drying temperature is 40–80°C.

[0024] According to some embodiments of the present invention, the calcination temperature is 200–450°C, and the calcination time is 3–6 hours.

[0025] According to some embodiments of the present invention, the mass ratio of the copper-containing precursor (calculated as CuO) to the silicon source (calculated as SiO2) is (3-15):(85-97).

[0026] According to some embodiments of the present invention, the molar ratio of the organoamine siloxane to the copper-containing precursor based on CuO is (1.5 to 3):1.

[0027] According to some embodiments of the present invention, the molar ratio of ammonia water (calculated as NH3·H2O) to copper-containing precursor (calculated as CuO) is (1~1.8):1.

[0028] In the preparation method of the dehydrogenation catalyst provided by this invention, the addition of ammonia water serves to hydrolyze the organoamine siloxane and the copper-containing precursor. Excessive use of ammonia water can cause the copper precipitate to undergo further coordination dissolution.

[0029] According to some embodiments of the present invention, the molar ratio of the alcohol component to the copper-containing precursor calculated as CuO is (10-20):1.

[0030] In the preparation method of the dehydrogenation catalyst provided by the present invention, the role of adding alcohol components is to reduce the surface tension of the solution, disrupt the solution micelle system, and make it easier for solid particles to separate.

[0031] According to some embodiments of the present invention, the method for preparing the catalyst includes:

[0032] (1) Mix an alcohol solution containing a copper precursor with an organic solution containing an organoamine siloxane and stir at room temperature for 18–36 h.

[0033] (2) Add ammonia water to the mixed solution in step (1) and stir for 2 to 8 hours;

[0034] (3) Add a silicon source to the mixed solution in step (2), heat to 40-80°C, and stir for 18-36 hours;

[0035] (4) Add the alcohol component dropwise to the mixed solution from step (3);

[0036] (5) The mixed solution from step (4) is centrifuged, and the resulting solid is washed with cyclohexane and acetone, dried overnight in a vacuum drying oven at 40-80°C, and calcined in a muffle furnace at 200-450°C to obtain the catalyst.

[0037] According to some embodiments of the present invention, the alcohol solvent used in the alcohol solution is selected from at least one of methanol, ethanol, and isopropanol.

[0038] According to some embodiments of the present invention, the organic solvent used in the organic solution is selected from at least one of acetone, n-hexane, cyclohexane, and methylcyclohexane.

[0039] According to some embodiments of the present invention, the catalyst is formed by an electric tablet press at a pressure of 5-10 MPa, and after crushing and sieving, 10-20 mesh catalyst particles are obtained.

[0040] Thirdly, the present invention provides the application of the catalyst described in the first aspect or the catalyst prepared by the preparation method described in the second aspect in catalytic dehydrogenation, especially in the dehydrogenation of diethylene glycol to p-dioxanone.

[0041] Fourthly, the present invention provides a method for the dehydrogenation of diethylene glycol to produce p-dioxanone, wherein the catalyst described in the first aspect or the catalyst prepared by the preparation method described in the second aspect is used for the catalytic reaction.

[0042] According to some embodiments of the present invention, the catalyst needs to be reduced before use.

[0043] According to some embodiments of the present invention, the reduction process is carried out in an atmosphere containing a reducing gas; the atmosphere containing the reducing gas includes at least one of hydrogen, ammonia, and carbon monoxide, and at least one of nitrogen, argon, and helium.

[0044] According to some embodiments of the present invention, the conditions for the reduction treatment include: a reduction temperature of 130–240°C, a reduction pressure of 0.1–3 MPa, and a reduction time of 4–8 h.

[0045] According to some embodiments of the present invention, the dehydrogenation reaction is carried out in an inert atmosphere; the inert atmosphere includes at least one of nitrogen, argon, and helium.

[0046] According to some embodiments of the present invention, the conditions for the dehydrogenation reaction include: a reaction temperature of 230–300°C, a reaction pressure of 0.01–0.4 MPa, and a feed liquid hourly space velocity (LHSV) of 0.1–2.5 h⁻¹. -1 .

[0047] The beneficial effects of this invention are at least as follows:

[0048] The dehydrogenation catalyst provided by this invention features low content and good dispersibility of the metal active component, low surface acidity, good stability, and long service life. When applied to the dehydrogenation of diethylene glycol to p-dioxanone, the catalyst exhibits high utilization of the active component, significantly suppresses side reactions, and substantially improves the selectivity of the target product. The application process is easy to implement, the equipment operation is simple, and energy and material consumption are low, significantly reducing the production cost of p-dioxanone. Detailed Implementation

[0049] To make the technical problem to be solved, the technical solution, and the beneficial effects of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely for illustrating this patent and do not limit the scope of protection of this invention in any way.

[0050] Unless otherwise defined, the technical terms used in the following embodiments have the same meaning as commonly understood by those skilled in the art. Unless otherwise specified, the reagents used in the following embodiments are conventional biochemical reagents; the raw materials, instruments, and equipment used in the following embodiments can all be obtained commercially or by existing methods; unless otherwise specified, the reagent dosages are those used in routine experimental operations; unless otherwise specified, the experimental methods are conventional methods.

[0051] In the various embodiments and comparative examples of the present invention, the performance data were tested according to the following test methods:

[0052] (1) After the reaction products are separated by condensation, the product components are analyzed by gas chromatography, and the conversion rate of diethylene glycol and the selectivity of the target product for dioxane are calculated.

[0053] (2) The Cu particle size was calculated using the Scherrer formula based on the XRD data. The XRD data were measured using a Philip X'pert Pro diffractometer. The X-ray source was Cu target Kα rays (λ = 0.15408 nm) filtered by a Ni filter, with an acquisition step size of 0.06 o / s, an X-ray tube operating voltage of 40 kV, and a current of 40 mA.

[0054] (3) The specific surface area and pore structure properties of the samples were tested using a Micromeritics ASAP-3020 physical adsorption instrument. Before the test, the samples were degassed at 300℃ for 3 hours, and the test was conducted at liquid nitrogen temperature (-196℃). The specific surface area of ​​the samples was calculated using the Brunauer-Emmett-Teller (BET) multilayer physical adsorption model.

[0055] (4) Cu+ The proportions were calculated from XPS data, which were performed using a PHI 5000 VersaProbe system with a monochromatic Al target Kα line source (1486.6 eV, 15 kW). Samples were reduced before testing, and the binding energy of all samples was corrected using an external C1s source (284.6 eV) to compensate for surface charge effects.

[0056] In the embodiments and comparative examples of this invention, room temperature refers to 20°C.

[0057] Example 1

[0058] Weigh 3.04 g of Cu(NO3)2·3H2O into a beaker and dissolve it in 20 mL of anhydrous ethanol. Separately, weigh 5.57 g of (3-aminopropyl)triethoxysilane and dissolve it in 50 mL of cyclohexane. Mix the two solutions and stir continuously for 24 h. Measure 2 mL of 28 wt% ammonia solution and add it to the mixture, stirring continuously for 4 h. Finally, weigh 7.49 g of amorphous silica and add it to the mixture. Heat the solution to 40 °C and stir continuously for 24 h. Then, add 10 mL of anhydrous ethanol dropwise to the solution. Centrifuge the resulting mixture at 10,000 rpm. Wash the solid three times with cyclohexane and acetone respectively, dry it in a vacuum drying oven at 60 °C for 12 h, and finally calcine it in a muffle furnace at 400 °C for 4 h to obtain the catalyst, designated CS-1. The powdered catalyst was prepared using an electric tablet press. The sample tablets were crushed and sieved to obtain catalyst particles with a particle size of 20-40 mesh, which were then ready for use.

[0059] 5 mL of catalyst was loaded into a fixed-bed reactor, and a hydrogen-nitrogen mixture (10 / 90, v / v) was introduced at a flow rate of 100 mL / min. The reactor was heated to 160 °C, and the system pressure was 0.5 MPa. The reduction treatment lasted for 6 h. After the reduction was completed, the atmosphere was switched to nitrogen at a total flow rate of 500 mL / min. The system pressure was adjusted to 0.2 MPa, and the temperature was 260 °C. The feedstock was then introduced into the reactor for dehydrogenation reaction at a liquid hourly space velocity (LISH) of 1 h⁻¹. -1 The reaction products were obtained after condensation. The conversion rate of DEG and the selectivity of the target product PDO were calculated after GC analysis. The results are shown in Table 1.

[0060] Catalyst properties, conversion of diethylene glycol, and selectivity for dioxane are shown in Table 1.

[0061] Example 2

[0062] Weigh 3.04 g of Cu(NO3)2·3H2O into a beaker and dissolve it in 20 mL of anhydrous ethanol. Separately, weigh 5.57 g of (3-aminopropyl)triethoxysilane and dissolve it in 50 mL of cyclohexane. Mix the two solutions and stir continuously for 24 h. Measure 2 mL of 28 wt% ammonia solution and add it to the mixture, stirring continuously for 4 h. Finally, weigh 25.97 g of TEOS and add it to the mixture. Heat the solution to 60 °C and stir continuously for 24 h. Then, add 10 mL of anhydrous ethanol dropwise to the solution. Centrifuge the resulting mixture at 10,000 rpm. Wash the solid three times with cyclohexane and acetone respectively, dry it in a vacuum drying oven at 60 °C for 12 h, and finally calcine it in a muffle furnace at 400 °C for 4 h to obtain the catalyst, designated CS-2. The powdered catalyst was prepared using an electric tablet press. The sample tablets were crushed and sieved to obtain catalyst particles with a particle size of 20-40 mesh, which were then ready for use.

[0063] 5 mL of catalyst was loaded into a fixed-bed reactor, and a carbon monoxide-nitrogen mixture (30 / 70, v / v) was introduced at a flow rate of 100 mL / min and heated to 180 °C. The system pressure was 0.2 MPa, and the reduction treatment lasted for 4 h. After the reduction was completed, the atmosphere was switched to nitrogen at a total flow rate of 500 mL / min. The system pressure was adjusted to 0.1 MPa, and the temperature was 280 °C. The feedstock was then introduced into the reactor for dehydrogenation reaction at a liquid hourly space velocity (LISH) of 1 h⁻¹. -1 The reaction products are obtained after condensation.

[0064] Catalyst properties, conversion of diethylene glycol, and selectivity for dioxane are shown in Table 1.

[0065] Example 3

[0066] Weigh 2.28 g of Cu2(CH3COO)4 into a beaker and dissolve it in 20 mL of anhydrous ethanol. Separately, weigh 5.57 g of (3-aminopropyl)triethoxysilane and dissolve it in 50 mL of cyclohexane. Mix the two solutions and stir continuously for 24 h. Measure 2 mL of 28 wt% ammonia solution and add it to the mixture, stirring continuously for 4 h. Finally, weigh 18.73 g of 40 wt% silica sol and add it to the mixture. Heat the solution to 40 °C and stir continuously for 24 h. Then, add 10 mL of anhydrous ethanol dropwise to the solution. Centrifuge the resulting mixture at 10,000 rpm. Wash the solid three times with cyclohexane and acetone respectively, dry it in a vacuum drying oven at 60 °C for 12 h, and finally calcine it in a muffle furnace at 400 °C for 4 h to obtain the catalyst, designated CS-3. The powdered catalyst was prepared using an electric tablet press. The sample tablets were crushed and sieved to obtain catalyst particles with a particle size of 20-40 mesh, which were then ready for use.

[0067] 5 mL of catalyst was loaded into a fixed-bed reactor, and a hydrogen-nitrogen mixture (10 / 90, v / v) was introduced at a flow rate of 200 mL / min and heated to 160 °C. The system pressure was 1 MPa, and the reduction treatment lasted for 4 h. After reduction, the atmosphere was switched to nitrogen at a total flow rate of 400 mL / min. The system pressure was adjusted to 0.1 MPa, and the temperature was 260 °C. The feedstock was then introduced into the reactor for dehydrogenation reaction at a liquid hourly space velocity (LHSV) of 0.5 h⁻¹. -1 The reaction products are obtained after condensation.

[0068] Catalyst properties, conversion of diethylene glycol, and selectivity for dioxane are shown in Table 1.

[0069] Example 4

[0070] Weigh 3.04 g of Cu(NO3)2·3H2O into a beaker and dissolve it in 20 mL of anhydrous ethanol. Separately, weigh 5.57 g of (3-aminopropyl)triethoxysilane and dissolve it in 50 mL of cyclohexane. Mix the two solutions and stir continuously for 24 h. Measure 2 mL of 28 wt% ammonia solution and add it to the mixture, stirring continuously for 4 h. Finally, weigh 45.75 g of sodium silicate and add it to the mixture. Heat the solution to 40 °C and stir continuously for 24 h. Then, add 10 mL of anhydrous ethanol dropwise to the solution. Centrifuge the resulting mixture at 10,000 rpm. Wash the solid three times with cyclohexane and acetone respectively, dry it in a vacuum drying oven at 60 °C for 12 h, and finally calcine it in a muffle furnace at 400 °C for 4 h to obtain the catalyst, designated CS-4. The powdered catalyst was prepared using an electric tablet press. The sample tablets were crushed and sieved to obtain catalyst particles with a particle size of 20-40 mesh, which were then ready for use.

[0071] 5 mL of catalyst was loaded into a fixed-bed reactor, and a hydrogen-argon mixture (20 / 80, v / v) was introduced at a flow rate of 100 mL / min. The reactor was heated to 160 °C, and the system pressure was 2 MPa. The reduction treatment lasted for 6 h. After the reduction was completed, the atmosphere was switched to helium at a total flow rate of 500 mL / min. The system pressure was adjusted to 0.4 MPa, and the temperature was 250 °C. The feedstock was then introduced into the reactor for dehydrogenation reaction at a liquid hourly space velocity (LISH) of 1 h⁻¹. -1 The reaction products are obtained after condensation.

[0072] Catalyst properties, conversion of diethylene glycol, and selectivity for dioxane are shown in Table 1.

[0073] Example 5

[0074] Weigh 3.13 g of CuSO4·5H2O into a beaker and dissolve it in 20 mL of anhydrous ethanol. Separately, weigh 4.51 g of (3-aminopropyl)trimethoxysilane and dissolve it in 50 mL of cyclohexane. Mix the two solutions and stir continuously for 24 h. Measure 2 mL of 28 wt% ammonia solution and add it to the mixture, stirring continuously for 4 h. Finally, weigh 7.49 g of amorphous silica and add it to the mixture. Heat the solution to 40 °C and stir continuously for 24 h. Then, add 10 mL of anhydrous ethanol dropwise to the solution. Centrifuge the resulting mixture at 12000 rpm. Wash the solid three times with cyclohexane and acetone respectively, dry it in a vacuum drying oven at 60 °C for 12 h, and finally calcine it in a muffle furnace at 350 °C for 4 h to obtain the catalyst, designated CS-5. The powdered catalyst was prepared using an electric tablet press. The sample tablets were crushed and sieved to obtain catalyst particles with a particle size of 20-40 mesh, which were then ready for use.

[0075] 5 mL of catalyst was loaded into a fixed-bed reactor, and a carbon monoxide-nitrogen mixture (20 / 80, v / v) was introduced at a flow rate of 100 mL / min and heated to 200 °C. The system pressure was 0.1 MPa, and the reduction treatment lasted for 4 h. After reduction, the atmosphere was switched to nitrogen at a total flow rate of 500 mL / min. The system pressure was adjusted to 0.2 MPa, and the temperature to 280 °C. The feedstock was then introduced into the reactor for dehydrogenation reaction at a liquid hourly space velocity (LHSV) of 0.2 h⁻¹. -1 The reaction products are obtained after condensation.

[0076] Catalyst properties, conversion of diethylene glycol, and selectivity for dioxane are shown in Table 1.

[0077] Comparative Example 1

[0078] The preparation and use of the catalyst were the same as in Example 1, except that 5.57 g of (3-aminopropyl)triethoxysilane was replaced with 5.24 g of TEOS. The catalyst was DB-1.

[0079] Catalyst properties, conversion of diethylene glycol, and selectivity for dioxane are shown in Table 1.

[0080] Comparative Example 2

[0081] The preparation and use of the catalyst were the same as in Example 1, except that 5.57 g of (3-aminopropyl)triethoxysilane was replaced with 5.24 g of TEOS and 1.41 g of propylamine. The catalyst was DB-2.

[0082] Catalyst properties, conversion of diethylene glycol, and selectivity for dioxane are shown in Table 1.

[0083] Comparative Example 3

[0084] 4.02 g of Cu(NO3)2·3H2O was weighed into a beaker, and 30 mL of deionized water was added and stirred to dissolve. Then, 10.0 g of amorphous silica support was added to the precursor salt solution, and the mixture was stirred vigorously at room temperature for 2 hours. The mixture was then transferred to an 80°C oil bath and stirred until the water was evaporated. It was dried in a vacuum drying oven at 60°C for 12 hours, and then calcined in a muffle furnace at 400°C for 4 hours. The powdered catalyst was prepared using an electric tablet press. The sample tablets were crushed and sieved to obtain catalyst particles with a particle size of 20–40 mesh, designated DB-3.

[0085] 5 mL of catalyst was loaded into a fixed-bed reactor, and a hydrogen-nitrogen mixture (10 / 90, v / v) was introduced at a flow rate of 100 mL / min. The reactor was heated to 160 °C, and the system pressure was 0.5 MPa. The reduction treatment lasted for 6 h. After the reduction was completed, the atmosphere was switched to nitrogen at a total flow rate of 500 mL / min. The system pressure was adjusted to 0.2 MPa, and the temperature was 260 °C. The feedstock was then introduced into the reactor for dehydrogenation reaction at a liquid hourly space velocity (LISH) of 1 h⁻¹. -1 The reaction products are obtained after condensation.

[0086] Catalyst properties, conversion of diethylene glycol, and selectivity for dioxane are shown in Table 1.

[0087] Table 1

[0088]

[0089] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A dehydrogenation catalyst, characterized in that, Based on the mass of the catalyst, it comprises 3–15 wt% of active metal oxide and 85–97 wt% of support; the active metal oxide includes CuO, and the support includes SiO2; the particle size of the metal active component after reduction of the catalyst is 0.5–3 nm. The catalyst, after being reduced to Cu + / (Cu 0 +Cu + The proportion is 35-70%; The surface acidity of the catalyst is 0.01–0.05 mmol / g.

2. The catalyst according to claim 1, characterized in that, The catalyst has a specific surface area of ​​250–450 m². 2 / g.

3. The method for preparing the catalyst according to claim 1 or 2, characterized in that, include: A mixed solution comprising a copper-containing precursor and an organoamine siloxane was obtained; Add ammonia water to the mixed solution and stir; A silicon source is added to the mixture, and the mixture is heated and stirred. An alcohol component is then added dropwise to the mixed solution, followed by solid-liquid separation. The solid component is collected, washed, dried, and calcined to obtain the catalyst.

4. The method for preparing the catalyst according to claim 3, characterized in that, The copper-containing precursor is selected from at least one of copper nitrate, copper sulfate, copper acetate, and copper chloride; And / or, the organoamine siloxane is selected from at least one of (3-aminopropyl)triethoxysilane, (3-aminopropyl)trimethoxysilane, and (2-aminoethyl)triethoxysilane; And / or, the concentration of the ammonia solution is 5–28 wt%; And / or, the silicon source is selected from at least one of tetraethyl silicate, silica sol, sodium silicate, and amorphous silicon oxide; And / or, the alcohol component is selected from at least one of methanol, ethanol, and isopropanol; And / or, the drying temperature is 40–80°C; And / or, the calcination temperature is 200–450°C.

5. The method for preparing the catalyst according to claim 3 or 4, characterized in that, The mass ratio of copper-containing precursor (calculated as CuO) to silicon source (calculated as SiO2) is (3-15):(85-97). And / or, the molar ratio of the organoamine siloxane to the copper-containing precursor based on CuO is (1.5-3):1; And / or, the molar ratio of ammonia water (calculated as NH3·H2O) to copper-containing precursor (calculated as CuO) is (1–1.8):1; And / or, the molar ratio of the alcohol component to the copper-containing precursor, calculated as CuO, is (10-20):

1.

6. The application of the catalyst according to claim 1 or 2 or the catalyst prepared by any one of claims 3-5 in catalytic dehydrogenation.

7. The application according to claim 6, characterized in that, The application is in the dehydrogenation of diethylene glycol to produce p-dioxanone.

8. A method for producing p-dioxanone by dehydrogenation of diethylene glycol, characterized in that, Catalysts prepared by the catalyst according to claim 1 or 2 or by the preparation method according to any one of claims 3-5 catalyze reactions.

9. The method according to claim 8, characterized in that, The catalyst needs to be reduced before use.

10. The method according to claim 9, characterized in that, The reduction process is carried out in an atmosphere containing a reducing gas; the atmosphere containing the reducing gas includes at least one of hydrogen, ammonia, and carbon monoxide, and at least one of nitrogen, argon, and helium. And / or, the conditions for the reduction treatment include: a reduction temperature of 130–240°C, a reduction pressure of 0.1–3 MPa, and a reduction time of 4–8 h.

11. The method according to any one of claims 8-10, characterized in that, The dehydrogenation reaction is carried out in an inert atmosphere; the inert atmosphere includes at least one of nitrogen, argon, and helium. And / or, the conditions for the dehydrogenation reaction include: a reaction temperature of 230–300°C, a reaction pressure of 0.01–0.4 MPa, and a feed liquid hourly space velocity of 0.1–2.5 h⁻¹. -1 .

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