Dehydrogenation catalyst, preparation method and application thereof, and method for preparing p-dioxanone by dehydrogenation of diethylene glycol

Abstract

The invention relates to the technical field of catalysts, and provides a dehydrogenation catalyst, a preparation method and application thereof, and a method for preparing p-dioxanone by diethylene glycol dehydrogenation. The dehydrogenation catalyst comprises 3-15 wt% of an active metal oxide and 85-97 wt% of a carrier based on the mass of the catalyst, the active metal oxide comprises CuO, and the carrier comprises SiO2; the particle size of the metal active component of the catalyst after reduction is 0.5-3 nm. The dehydrogenation catalyst provided by the invention has the characteristics of low content of metal active components, good dispersity, low surface acid content, good stability and long service life. The dehydrogenation catalyst is applied to a reaction for preparing p-dioxanone through diethylene glycol dehydrogenation, has the characteristic of high utilization rate of active components, and can obviously inhibit side reactions and obviously improve the selectivity of a target product; the application process conditions are easy to realize, and the production cost of p-dioxanone can be greatly reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts, and more specifically, to a dehydrogenation catalyst and its preparation method and application, and a method for dehydrogenating diethylene glycol to prepare p-dioxanone. Background Art

[0002] Aliphatic polyester poly(p-dioxanone) (PPDO) has good biocompatibility, bioabsorbability and biodegradability due to the large number of ether bonds and ester bonds in its molecular chain. Its bulk and derivatives are widely used in the fields of biomedical materials such as surgical sutures, bone plates, and tissue repair. PPDO is mainly obtained by ring-opening polymerization of p-dioxanone (PDO). To prepare PPDO with excellent properties, high-purity monomer PDO must be prepared first. However, so far, due to difficult synthesis conditions and high preparation costs, PDO is not a commonly available commercial product, which has hindered the further popularization and application of PPDO. Among the limited research reports on the synthesis of PDO, using inexpensive and readily available diethylene glycol as a raw material and directly synthesizing PDO by catalytic dehydrogenation cyclization under the action of a dehydrogenation catalyst is the most economical and simple route. The composition of the dehydrogenation catalyst used mainly includes alumina, silica, molecular sieve as carriers and transition metals such as copper, silver, platinum, and zinc supported on the carriers. In this route, exploring and finding a dehydrogenation catalyst with high activity, good selectivity, and excellent stability is the key to low-cost synthesis of high-purity PDO.

[0003] CN112473675A discloses a catalyst for preparing p-dioxanone and a method for preparing p-dioxanone. The catalyst contains 46.2-46.9% copper oxide, 0.1-1% sodium oxide, and the balance is silica, and can be used for the reaction of preparing p-dioxanone; however, the catalyst has a high content of active components and strong surface alkalinity, and there are many side reactions. CN 1739852A discloses a catalyst for gas-phase dehydrogenation of diethylene glycol to PDO. The catalyst is prepared by a co-precipitation method, and the main body is a copper-zinc compound supported on an inert carrier, and has good conversion and selectivity, but the content of the active component is high, between 20-90%. CN112724122A discloses a supported dehydrogenation catalyst using hydroxyapatite as a carrier, and the active component is a transition metal of Group VIII B or Group I B. The catalyst has good thermal stability and good recycling performance. However, this catalyst needs to use an autoclave reactor to dehydrogenate diethylene glycol to PDO in the presence of oxygen and a solvent. The use conditions are relatively harsh, and the reaction and separation processes are complex, which is not conducive to large-scale production.

[0004] In the prior art, the catalysts used for the dehydrogenation of diethylene glycol to p-dioxanone all have problems to varying degrees, such as high content of active components, low utilization rate, poor catalyst performance, and harsh use process conditions. Therefore, there is an urgent need to develop a catalyst for the dehydrogenation of diethylene glycol to p-dioxanone with a low content of active components, good catalytic performance, and low requirements for use process conditions. Summary of the Invention

[0005] The purpose of the present invention is to provide a dehydrogenation catalyst and a preparation method thereof to solve the technical problems in the prior art that the catalysts used for the dehydrogenation of diethylene glycol to p-dioxanone have high content of active components, poor catalyst performance, and harsh use process conditions.

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

[0007] In the first aspect, the present invention provides a dehydrogenation catalyst, based on the mass of the catalyst, comprising 3-15 wt% of active metal oxide and 85-97 wt% of carrier; the active metal oxide includes CuO, and the carrier includes SiO 2 ; the particle size of the metal active component after the catalyst is reduced is 0.5-3 nm.

[0008] The content of the active component CuO in the dehydrogenation catalyst provided by the present invention is low, only 3-15 wt%; moreover, the particle size of the metal active component after reduction is small, the dispersion degree is high, and the distribution is uniform.

[0009] According to some embodiments of the present invention, the ratio of Cu + / (Cu 0 +Cu + ) of the catalyst after reduction is 35-70%.

[0010] According to some embodiments of the present invention, the ratio of Cu + / (Cu 0 +Cu + ) of the catalyst after reduction is 40-65%.

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

[0012] In the reaction of dehydrogenating diethylene glycol to p-dioxanone, the most significant side reaction is the dehydration of raw materials to form dioxane. The low surface acid amount of the dehydrogenation catalyst provided by the present invention can effectively inhibit the occurrence of this side reaction and improve the selectivity of the target product.

[0013] According to some embodiments of the present invention, the specific surface area of the catalyst is 250-450 m 2 / g.

[0014] According to some embodiments of the present invention, the specific surface area of the catalyst is 300 - 440 m 2 / g.

[0015] According to some embodiments of the present invention, the specific surface area of the catalyst is 350 - 430 m 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 including 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, 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] In the preparation method of the dehydrogenation catalyst provided by the present invention, by using an organoamine siloxane to coat the copper-containing precursor, the aggregation of metal active components during the synthesis process is restricted. The single-dispersed metal active components react with the hydroxyl groups on the surface of the silicon source through the organoamine ends, grafting the metal active components onto the surface of the carrier to obtain uniform single-dispersed active sites, resulting in a high dispersion degree of the metal active components and being not prone to an increase in particle size upon heating, thereby enabling the catalyst to have excellent thermal stability and being beneficial to the long-cycle life of the catalyst. In addition, the number of hydroxyl groups on the catalyst surface is reduced by reacting with the organoamine, lowering the surface acid amount 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 orthosilicate (TEOS), silica sol, sodium silicate, and amorphous silica.

[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. The calcination time is 3-6 h.

[0025] According to some embodiments of the present invention, the mass ratio of the copper-containing precursor based on CuO to the silicon source based on SiO 2 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 (1.5-3):1.

[0027] According to some embodiments of the present invention, the molar ratio of ammonia water based on NH 3 ·H 2 O to the copper-containing precursor based on CuO is (1-1.8):1.

[0028] In the preparation method of the dehydrogenation catalyst provided by the present invention, the role of adding ammonia water is to hydrolyze the organoamine siloxane and the copper-containing precursor. If the dosage of ammonia water is too much, it will cause the redissolution of the copper-containing precipitate by coordination.

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

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

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

[0032] (1) Mix the alcohol solution containing the copper-containing precursor with the organic solution containing the 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 2-8 h;

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

[0035] (4) Dropwise add the alcohol component to the mixed solution in step (3);

[0036] (5) Centrifuge the mixed solution in step (4), wash the obtained solid with cyclohexane and acetone, dry it overnight in a vacuum drying oven at 40-80°C, and calcine it 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 screening, a granular catalyst of 10-20 mesh is obtained.

[0040] In a third aspect, the present invention provides the use 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] In a fourth aspect, the present invention provides a method for dehydrogenating diethylene glycol to p-dioxanone, using the catalyst described in the first aspect or the catalyst prepared by the preparation method described in the second aspect for catalytic reaction.

[0042] According to some embodiments of the present invention, the catalyst needs to be subjected to a reduction treatment before use.

[0043] According to some embodiments of the present invention, the reduction treatment is carried out in an atmosphere containing a reducing gas; the atmosphere containing a 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 of the reduction treatment include: the reduction temperature is 130-240 °C, the reduction pressure is 0.1-3 MPa, and the reduction time is 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 of the dehydrogenation reaction include: the reaction temperature is 230-300 °C, the reaction pressure is 0.01-0.4 MPa, and the liquid hourly space velocity (LHSV) of the raw material feed is 0.1-2.5 h -1 .

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

[0048] The dehydrogenation catalyst provided by the present invention has the characteristics of low content of metal active components, good dispersion, low surface acid amount, good stability and long service life. When the dehydrogenation catalyst is applied to the reaction of dehydrogenating diethylene glycol to produce 1,4-dioxane-2-one, it has the characteristics of high utilization rate of active components, can significantly inhibit the occurrence of side reactions, and significantly improve the selectivity of the target product; the application process conditions are easy to achieve, the equipment operation steps are simple, and the energy and material consumption are small, which can greatly reduce the production cost of 1,4-dioxane-2-one. Detailed Embodiments

[0049] In order to make the technical problems to be solved, technical solutions and beneficial effects of the present invention clearer, the present invention will be further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain this patent in detail and do not limit the protection scope of the present invention in any way.

[0050] Unless otherwise defined, the technical terms used in the following examples have the same meanings as commonly understood by those skilled in the art to which the present invention belongs. The reagents used in the following examples are all conventional biochemical reagents unless otherwise specified; the raw materials, instruments and equipment used in the following examples can all be obtained through market purchase or can be obtained by existing methods; the reagent dosages are all the reagent dosages in conventional experimental operations unless otherwise specified; the experimental methods are all conventional methods unless otherwise specified.

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

[0052] (1) After the reaction products are condensed and separated, the product components are analyzed by gas chromatography, and the conversion rate of diethylene glycol and the selectivity of the target product 1,4-dioxane-2-one are calculated.

[0053] (2) The Cu particle size is calculated according to the Scherrer formula from the XRD data. The XRD data is tested by a Philip X’pert Pro diffractometer. The X-ray radiation source is Cu target Kα ray (λ = 0.15408nm) filtered by a Ni filter, the collection step is 0.06° / s, the X-ray tube operating voltage is 40kV, and the current is 40mA.

[0054] (3) The specific surface area and pore structure properties of the sample are tested using a Micromeritics ASAP-3020 physical adsorption instrument. The sample is degassed at 300°C for 3h before testing, and the testing is carried out at liquid nitrogen temperature (-196°C). The specific surface area of the sample is calculated by the Brunauer-Emmett-Teller (BET) multi-layer physical adsorption model.

[0055] (4) Cu+ The ratio was calculated from XPS data. The XPS test was carried out using a PHI 5000 VersaProbe system, and the X-ray source was a monochromatic Al target Kα line (1486.6 eV, 15 kW). The samples were reduced before testing, and the binding energy of all samples was corrected using an external C1s (284.6 eV) to compensate for the surface charging effect of the samples.

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

[0057] Example 1

[0058] Weigh 3.04 g of Cu(NO 3 ) 2 ·3H 2 O into a beaker, and add 20 mL of anhydrous ethanol to dissolve it; weigh another 5.57 g of (3-aminopropyl)triethoxysilane and dissolve it in 50 mL of cyclohexane; mix the above two solutions and stir continuously for 24 h. Measure 2 mL of ammonia water with a concentration of 28 wt%, add it to the above mixture, and stir continuously for 4 h. Finally, weigh 7.49 g of amorphous silica and put it into the above 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 obtained mixture at a speed of 10000 rpm, wash the obtained solid three times with cyclohexane and acetone respectively, dry it in a vacuum drying oven at 60 °C for 12 h, and finally put it into a muffle furnace and calcine it at 400 °C for 4 h to obtain a catalyst denoted as CS-1. The powdered catalyst was pressed by an electric tablet press, and the sample tablets were crushed and screened to obtain catalyst particles with a particle size of 20-40 mesh for standby.

[0059] Take 5 mL of the catalyst and load it into a fixed-bed reactor, introduce a hydrogen-nitrogen mixture (10 / 90, v / v) at a flow rate of 100 mL / min and heat it to 160 °C, with a system pressure of 0.5 MPa, and carry out reduction treatment for 6 h. After the reduction is completed, the atmosphere is switched to nitrogen, the total flow rate is 500 mL / min, the system pressure is adjusted to 0.2 MPa, and the temperature is 260 °C. Then, introduce the raw materials into the reactor for dehydrogenation reaction, and the liquid hourly space velocity is 1 h -1 . After condensation, the reaction products are obtained. After GC analysis, the conversion rate of DEG and the selectivity of the target product PDO are calculated, and the results are shown in Table 1.

[0060] The catalyst property data, the conversion rate of diethylene glycol, and the selectivity of p-dioxanone are shown in Table 1.

[0061] Example 2

[0062] Weigh 3.04 g of Cu(NO 3 ) 2 ·3H 2In a beaker, add 20 mL of absolute ethanol to dissolve; separately weigh 5.57 g of (3-aminopropyl)triethoxysilane and dissolve it in 50 mL of cyclohexane; mix the above two solutions and continuously stir for 24 h. Measure 2 mL of ammonia water with a concentration of 28 wt%, add it to the above mixture, and continuously stir for 4 h. Finally, weigh 25.97 g of TEOS, put it into the above mixture, heat the solution to 60 °C, and continuously stir for 24 h. Subsequently, add 10 mL of absolute ethanol dropwise to the solution. Centrifuge the obtained mixture at a centrifuge speed of 10000 rpm. Wash the obtained solid three times with cyclohexane and acetone respectively, dry it in a vacuum drying oven at 60 °C for 12 h, and finally put it into a muffle furnace and calcine it at 400 °C for 4 h to obtain a catalyst denoted as CS-2. The powdered catalyst is pressed by an electric tablet press, and the sample tablets are crushed and screened to obtain catalyst particles with a particle size of 20-40 mesh for standby.

[0063] Take 5 mL of the catalyst and load it into a fixed-bed reactor. Pass a carbon monoxide-nitrogen mixed gas (30 / 70, v / v) at a flow rate of 100 mL / min and heat it to 180 °C. The system pressure is 0.2 MPa, and perform a reduction treatment for 4 h. After the reduction is completed, switch the atmosphere to nitrogen with a total flow rate of 500 mL / min, adjust the system pressure to 0.1 MPa, and the temperature to 280 °C. Feed the raw materials into the reactor for dehydrogenation reaction with a liquid hourly space velocity of 1 h -1 . The reaction products are obtained after condensation.

[0064] The catalyst property data, the conversion rate of diethylene glycol, and the selectivity of p-dioxanone are shown in Table 1.

[0065] Example 3

[0066] Weigh 2.28 g of Cu 2 (CH 3 COO) 4 In a beaker, add 20 mL of absolute ethanol to dissolve; separately weigh 5.57 g of (3-aminopropyl)triethoxysilane and dissolve it in 50 mL of cyclohexane; mix the above two solutions and continuously stir for 24 h. Measure 2 mL of ammonia water with a concentration of 28 wt%, add it to the above mixture, and continuously stir for 4 h. Finally, weigh 18.73 g of 40 wt% silica sol, put it into the above mixture, heat the solution to 40 °C, and continuously stir for 24 h. Subsequently, add 10 mL of absolute ethanol dropwise to the solution. Centrifuge the obtained mixture at a centrifuge speed of 10000 rpm. Wash the obtained solid three times with cyclohexane and acetone respectively, dry it in a vacuum drying oven at 60 °C for 12 h, and finally put it into a muffle furnace and calcine it at 400 °C for 4 h to obtain a catalyst denoted as CS-3. The powdered catalyst is pressed by an electric tablet press, and the sample tablets are crushed and screened to obtain catalyst particles with a particle size of 20-40 mesh for standby.

[0067] 5 mL of the catalyst was charged into a fixed-bed reactor, and a hydrogen-nitrogen mixed gas (10 / 90, v / v) at a flow rate of 200 mL / min was introduced and heated to 160 °C. The system pressure was 1 MPa, and the reduction treatment was carried out for 4 h. After the reduction, the atmosphere was switched to nitrogen, the total flow rate was 400 mL / min, the system pressure was adjusted to 0.1 MPa, and the temperature was 260 °C. The raw material was introduced into the reactor for dehydrogenation reaction, and the liquid hourly space velocity was 0.5 h -1 . The reaction product was obtained after condensation.

[0068] The catalyst property data, the conversion rate of diethylene glycol, and the selectivity of p-dioxanone are shown in Table 1.

[0069] Example 4

[0070] 3.04 g of Cu(NO 3 ) 2 ·3H 2 O was weighed and placed in a beaker, and 20 mL of absolute ethanol was added to dissolve it; another 5.57 g of (3-aminopropyl)triethoxysilane was weighed and dissolved in 50 mL of cyclohexane; the above two solutions were mixed and stirred continuously for 24 h. 2 mL of ammonia water with a concentration of 28 wt% was measured and added to the above mixture, and stirred continuously for 4 h. Finally, 45.75 g of sodium silicate was weighed and put into the above mixture, the solution was heated to 40 °C, and stirred continuously for 24 h. Subsequently, 10 mL of absolute ethanol was added dropwise to the solution. The obtained mixture was centrifuged at a speed of 10,000 rpm, and the obtained solid was washed three times with cyclohexane and acetone respectively, dried in a vacuum drying oven at 60 °C for 12 h, and finally placed in a muffle furnace and calcined at 400 °C for 4 h to obtain the catalyst denoted as CS-4. The powder catalyst was pressed by an electric tablet press, and the sample tablets were crushed and screened to obtain catalyst particles with a particle size of 20-40 mesh for standby.

[0071] 5 mL of the catalyst was charged into a fixed-bed reactor, and a hydrogen-argon mixed gas (20 / 80, v / v) at a flow rate of 100 mL / min was introduced and heated to 160 °C. The system pressure was 2 MPa, and the reduction treatment was carried out for 6 h. After the reduction, the atmosphere was switched to helium, the total flow rate was 500 mL / min, the system pressure was adjusted to 0.4 MPa, and the temperature was 250 °C. The raw material was introduced into the reactor for dehydrogenation reaction, and the liquid hourly space velocity was 1 h -1 . The reaction product was obtained after condensation.

[0072] The catalyst property data, the conversion rate of diethylene glycol, and the selectivity of p-dioxanone are shown in Table 1.

[0073] Example 5

[0074] 3.13 g of CuSO 4 ·5H 2In a beaker, 20 mL of anhydrous ethanol was added for dissolution; another 4.51 g of (3-aminopropyl)trimethoxysilane was weighed and dissolved in 50 mL of cyclohexane; the above two solutions were mixed and continuously stirred for 24 h. 2 mL of ammonia water with a concentration of 28 wt% was measured and added to the above mixture, and continuously stirred for 4 h. Finally, 7.49 g of amorphous silica was weighed and put into the above mixture, the solution was heated to 40 °C, and continuously stirred for 24 h. Subsequently, 10 mL of anhydrous ethanol was added dropwise to the solution. The obtained mixture was centrifuged at a speed of 12,000 rpm, and the obtained solid was washed three times with cyclohexane and acetone respectively, dried in a vacuum drying oven at 60 °C for 12 h, and finally calcined in a muffle furnace at 350 °C for 4 h to obtain a catalyst denoted as CS-5. The powder catalyst was pressed by an electric tablet press, and the sample tablets were crushed and screened to obtain catalyst particles with a particle size of 20 - 40 mesh for standby.

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

[0076] The catalyst property data, the conversion rate of diethylene glycol, and the selectivity to p-dioxanone are shown in Table 1.

[0077] Comparative Example 1

[0078] The preparation and use method of the catalyst were referred to Example 1, the difference was only that: 5.57 g of (3-aminopropyl)triethoxysilane was replaced by 5.24 g of TEOS. The catalyst was DB-1.

[0079] The catalyst property data, the conversion rate of diethylene glycol, and the selectivity to p-dioxanone are shown in Table 1.

[0080] Comparative Example 2

[0081] The preparation and use method of the catalyst were referred to Example 1, the difference was only that: 5.57 g of (3-aminopropyl)triethoxysilane was replaced by 5.24 g of TEOS and 1.41 g of propylamine. The catalyst was DB-2.

[0082] The catalyst property data, the conversion rate of diethylene glycol, and the selectivity to p-dioxanone are shown in Table 1.

[0083] Comparative Example 3

[0084] Weigh 4.02 g of Cu(NO 3 ) 2 ·3H 2 O into a beaker. After adding 30 mL of deionized water and stirring until dissolved, add 10.0 g of amorphous silica support to the dissolved precursor salt. Continuously stir vigorously at room temperature for 2 h. Then transfer the mixture to an 80 °C oil bath and keep stirring until the water is completely evaporated. Dry it in a vacuum drying oven at 60 °C for 12 h, and then place it in a muffle furnace and calcine at 400 °C for 4 h. The powder catalyst is pressed by an electric tablet press. The sample tablets are crushed and screened to obtain catalyst particles with a particle size of 20 - 40 mesh, denoted as DB-3.

[0085] Put 5 mL of the catalyst into a fixed-bed reactor, introduce a hydrogen-nitrogen mixture (10 / 90, v / v) at a flow rate of 100 mL / min and heat it to 160 °C. The system pressure is 0.5 MPa, and carry out reduction treatment for 6 h. After the reduction is completed, switch the atmosphere to nitrogen, with a total flow rate of 500 mL / min, adjust the system pressure to 0.2 MPa, and the temperature to 260 °C. Feed the raw materials into the reactor for dehydrogenation reaction, and the liquid hourly space velocity is 1 h -1 . The reaction products are obtained after condensation.

[0086] The catalyst property data, the conversion rate of diethylene glycol, and the selectivity of p-dioxanone are shown in Table 1.

[0087] Table 1

[0088]

[0089] It should be noted that the above-described embodiments are only used to explain the present invention and do not constitute any limitation to the present invention. The present invention has been described by referring to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words rather than limiting words. Modifications can be made to the present invention within the scope of the claims of the present invention as stipulated, and the present invention can be revised without departing from the scope and spirit of the present invention. Although the present invention described therein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed therein. On the contrary, the present invention can be extended to all other methods and applications with the same functions.

Claims

1. A dehydrogenation catalyst, characterized in that, Based on the mass of the catalyst, it includes 3 to 15 wt% of active metal oxide and 85 to 97 wt% of carrier; the active metal oxide includes CuO, and the carrier includes SiO 2 ; the particle size of the metal active component of the catalyst after reduction is 0.5 to 3 nm.

2. The catalyst according to claim 1, characterized in that, The Cu of the catalyst after reduction + / (Cu 0 +Cu + ) is in the range of 35% to 70%.

3. The catalyst according to claim 1 or 2, characterized in that, the surface acid amount of the catalyst is 0.01 - 0.05 mmol / g; and / or, the specific surface area of the catalyst is 250 to 450 m 2 / g.

4. A method for preparing the catalyst according to any one of claims 1 - 3, characterized in that, 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, 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.

5. The method for preparing the catalyst according to claim 4, 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 water is 5 - 28 wt%; and / or, the silicon source is selected from at least one of tetraethyl orthosilicate, silica sol, sodium silicate, and amorphous silica; 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.

6. The method for preparing the catalyst according to claim 4 or 5, characterized in that, The mass ratio of the copper-containing precursor calculated as CuO to the silicon source calculated as SiO 2 is (3 to 15):(85 to 97); and / or, the molar ratio of the organoamine siloxane to the copper-containing precursor calculated as CuO is (1.5 - 3):1; and / or, with NH 3 ·H 2 The molar ratio of ammonia water calculated as NH·H₂O to the copper-containing precursor calculated as CuO is (1 to 1.8):1; and / or, the molar ratio of the alcohol component to the copper-containing precursor calculated as CuO is (10 - 20):

1.

7. The application of the catalyst according to any one of claims 1 - 3 or the catalyst prepared by the preparation method according to any one of claims 4 - 6 in catalyzing dehydrogenation, especially in the dehydrogenation of diethylene glycol to p-dioxanone.

8. A method for dehydrogenating diethylene glycol to p-dioxanone, characterized in that, using the catalyst according to any one of claims 1 - 3 or the catalyst prepared by the preparation method according to any one of claims 4 - 6 for catalytic reaction.

9. The method according to claim 8, characterized in that, the catalyst needs to be subjected to a reduction treatment before use; preferably, the reduction treatment is carried out in an atmosphere containing a reducing gas; the atmosphere containing a 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 of the reduction treatment include: the reduction temperature is 130 - 240 °C, the reduction pressure is 0.1 - 3 MPa, and the reduction time is 4 - 8 h.

10. The method according to claim 8 or 9, 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: the reaction temperature is 230 to 300 °C, the reaction pressure is 0.01 to 0.4 MPa, and the liquid hourly space velocity of the raw material feed is 0.1 to 2.5 h -1 .

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