A core-shell structure allyl acetate catalyst and its preparation method and application

Abstract

The present invention discloses a core-shell structured allyl acetate catalyst, its preparation method, and application. The catalyst comprises a carrier core, and an active component coating and a co-active component coating sequentially coated on the outer surface of the carrier. The carrier is selected from titanium nitride, carbon nitride, vanadium carbide, and titanium carbide. The active component coating comprises an active metal selected from metals such as Pd, Pt, Au, Cu, and Zn, a ligand selected from HHTP, hexasubstituted benzene, and hexasubstituted benzophenone. The substrate is selected from at least one of silica sol, graphene, and silicon powder, preferably graphene or silica sol. The co-active component coating comprises a co-active metal salt and a matrix, the co-active metal salt being selected from alkali metal acetates. The matrix is ​​selected from silica sol, graphene, and silicon powder. The catalyst has the characteristics of high active component dispersion, low activation temperature, high space-time yield, good thermal conductivity, high product selectivity, good stability, and long catalyst life.

Description

Technical Field

[0001] The invention relates to a core-shell structured allyl acetate catalyst and a preparation method thereof, in particular to a catalyst used for synthesizing allyl acetate from acetic acid, oxygen and propylene. Background Art

[0002] Allyl acetate is an important organic chemical raw material. The synthesis of allyl acetate using propylene, oxygen and acetic acid as raw materials using acetyl oxidation technology has problems such as low time and space yield and poor selectivity.

[0003] US3917676 discloses a method for preparing allyl acetate. The method involves directly loading the active component onto a carrier, drying it, and then reducing it to form elemental metal active centers. Potassium acetate, a co-catalyst, is then added to produce a catalyst for synthesizing allyl acetate. The catalyst obtained by this method exhibits low activity and selectivity.

[0004] CN 1131199C discloses an oxyacylation catalyst for preparing allyl acetate. By adding metallic tin or a mixture of tin and an additional promoter metal during the preparation process, it was found that the addition of tin effectively increases the catalyst life without adding water to the raw materials. However, since water is generated during the oxyacylation reaction and acts as a heat transfer medium, this method is not advantageous for industrial application.

[0005] CN101657259B discloses a method for preparing a catalyst loaded with a primary active component, a precious metal, and a secondary active component, a metal. The method involves adding palladium, the primary active component, and gold, the secondary active component, to an impregnation tank, rotating the metals onto a carrier, drying, precipitating, and reducing the metals to obtain a precursor. Potassium acetate is then impregnated onto the precursor and dried to obtain the catalyst. The catalyst obtained by this method has low space-time yield and selectivity.

[0006] The allyl acetate catalysts prepared by the above inventions all suffer from low space-time yield and selectivity for the target product, as well as poor heat transfer, making them unsuitable for industrial production. Therefore, it is hoped that, building on existing technologies, improvements to the catalyst and catalyst preparation methods will lead to the development of a catalyst and preparation method for allyl acetate with greater industrial applicability. Summary of the Invention

[0007] To address the above-mentioned deficiencies in the prior art, the present invention provides a core-shell structured allyl acetate catalyst and a method for preparing the same. The catalyst has a multi-stage "core-shell" structure, comprising a carrier as a core, and an active component coating and a co-active component coating coated on the carrier.

[0008] The present invention produces an allyl acetate catalyst with a multi-stage "core-shell" structure by sequentially coating a precursor with a coating liquid containing an active component, a ligand, and a matrix, and a coating liquid containing a co-active component and a matrix. The catalyst exhibits high active component dispersion, a low activation temperature, a high space-time yield, good thermal conductivity, high product selectivity, excellent stability, and a long catalyst life.

[0009] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0010] The present invention provides a core-shell structured allyl acetate catalyst, which comprises a carrier core, and an active component coating and a co-active component coating sequentially coated on the outer surface of the carrier;

[0011] The carrier is selected from at least one of titanium nitride, carbon nitride, vanadium carbide, and titanium carbide, preferably vanadium carbide;

[0012] The active component coating comprises an active metal, a ligand and a matrix, wherein the active metal is selected from at least one of metals Pd, Pt, Au, Cu and Zn, preferably at least one of Pd, Au and Cu; the ligand is selected from at least one of HHTP (2,3,8,9,14,15-hexahydroxytriphenylcycloalkyne), hexasubstituted benzene and hexasubstituted benzophenone; and the matrix is ​​selected from at least one of silica sol, graphene and silicon powder, preferably at least one of graphene and silica sol.

[0013] The co-active component coating comprises a co-active metal salt and a matrix, wherein the co-active metal salt is selected from at least one of alkali metal acetates, preferably sodium acetate and / or potassium acetate; and the matrix is ​​selected from at least one of silica sol, graphene, and silicon powder, preferably at least one of graphene and silica sol.

[0014] In the present invention, the active component coating loading is 0.2 to 25.0 wt%, based on the mass of the carrier;

[0015] In the active component coating, based on the mass of the carrier, the active metal content is 0.1-10 wt%, preferably 1-10 wt%, the ligand content is 1.0-20.0 wt%, preferably 5.0-15.0 wt%, and the matrix content is 0.1-10 wt%, preferably 1-10 wt%.

[0016] In the present invention, the loading amount of the co-active component coating is 0.2 to 25.0 wt%, based on the mass of the carrier;

[0017] In the co-active component coating, based on the mass of the carrier, the content of the co-active metal salt is 0.1 to 20 wt%, preferably 1 to 15.0 wt%; the content of the matrix is ​​0.1 to 10.0 wt%, preferably 1.0 to 5.0 wt%.

[0018] In the present invention, the core-shell structure allyl acetate catalyst has a particle size of 2 to 9 mm, preferably 4 to 6 mm; a specific surface area of ​​30 to 350 m 2 / g, preferably 50 to 250 m 2 / g; pore volume is 0.1~1.0cm 3 / g, preferably 0.2 to 0.7 cm 3 / g; pore diameter is 5 to 25 nm, preferably 8 to 20 nm.

[0019] The present invention also provides a method for preparing the above-mentioned core-shell structure allyl acetate catalyst. In some specific examples, the active component is formed into a single metal atom by thermal spray coating, precipitation and reduction, and loaded on the surface of the carrier; wherein, thermal spray coating can enhance the anchoring effect between the active metal salt and the carrier, and form a loose pore structure, which can ensure that the active metal salt can be loaded on the carrier according to a predetermined state, and complete the subsequent preparation process on the basis of maintaining the distribution balance, thereby avoiding the uneven distribution caused by the difficulty in controlling the active component sites during the catalyst preparation process, thereby affecting the activity and selectivity of the catalyst, and causing some active components to be difficult to utilize and affecting the economy of the catalyst preparation; at the same time, it can ensure that the obtained product distribution will not cause secondary reactions to form carbon deposits and reduce activity and selectivity due to the difficulty in diffusion due to the small pore size; the auxiliary active component is loaded by vacuum filtration deposition, wherein, vacuum filtration deposition can enhance the anchoring effect between the auxiliary active metal salt and the precursor, and avoid the shedding of the auxiliary active component to reduce activity and selectivity.

[0020] In a specific embodiment of the present invention, as a preferred example, the present invention provides a method for preparing a core-shell structured allyl acetate catalyst, the steps comprising:

[0021] (1) A metal salt solution containing an active component is mixed with a ligand to undergo a coordination reaction, and then a matrix is ​​added to the mixture to obtain a coating liquid 1, which is then thermally sprayed onto a support surface to obtain a precursor A;

[0022] (2) adding the precursor A obtained in step (1) to an aqueous solution of a precipitant to carry out a precipitation reaction, then adding a reducing agent to carry out a reduction reaction, and washing and drying to obtain a precursor B;

[0023] (3) The metal salt solution containing the auxiliary active component is mixed with the matrix to obtain a coating liquid 2, and the coating liquid 2 is deposited on the surface of the precursor B by vacuum filtration, and dried to obtain a core-shell structured allyl acetate catalyst.

[0024] In step (1) of the present invention, the metal salt solution containing the active component is an aqueous solution with a concentration of 5 to 30 wt%, preferably 10 to 20 wt%;

[0025] The metal salt containing the active component is selected from at least one of the chlorides, nitrates and acetates of Pd, Pt, Au, Cu and Zn, preferably at least one of the chlorides of Pd, Au and Cu.

[0026] In step (1) of the present invention, the ligand is selected from at least one of HHTP, hexasubstituted benzene and hexasubstituted benzoacene, preferably HHTP;

[0027] The mass ratio of the ligand to the metal in the metal salt solution containing the active component is 1:0.1-10, preferably 1:0.5-5.

[0028] In step (1) of the present invention, the matrix is ​​selected from at least one of silica sol, graphene, and silicon powder, preferably at least one of graphene and silica sol;

[0029] The mass ratio of the matrix to the metal in the metal salt solution containing the active component is 1:0.1-5, preferably 1:0.2-3.

[0030] In step (1) of the present invention, the carrier is selected from at least one of titanium nitride, carbon nitride, vanadium carbide, and titanium carbide, preferably vanadium carbide;

[0031] The mass ratio of the carrier to the metal salt containing the active component in the metal salt solution containing the active component is 1 to 100:1, preferably 2 to 50:1.

[0032] In step (1) of the present invention, the coordination reaction is carried out at a temperature of 10 to 50° C., preferably 20 to 30° C., and for a time of 10 to 72 hours, preferably 20 to 40 hours.

[0033] In step (1) of the present invention, the thermal spray coating temperature is 100-200°C, for example, 100°C, 150°C, 200°C, preferably 120-150°C; the time is 5-30 min, for example, 10 min, 20 min, 30 min, preferably 10-20 min.

[0034] In step (2) of the present invention, the aqueous solution of the precipitant has a concentration of 1 to 20 wt%, such as 3 wt%, 8 wt%, 15 wt%, preferably 5 to 10 wt%;

[0035] The precipitant is selected from at least one of potassium hydroxide, sodium hydroxide, potassium carbonate, sodium carbonate, potassium silicate, and sodium silicate, preferably at least one of sodium hydroxide, sodium silicate, and sodium carbonate;

[0036] The amount of the aqueous solution of the precipitant, calculated on the basis of the precipitant therein, is 1 to 20 times, for example 3 times, 10 times, 15 times, preferably 1 to 5 times, the molar amount of the metal in the metal salt solution containing the active component in step (1).

[0037] In step (2) of the present invention, the precipitation reaction temperature is 10-50°C, for example, 15°C, 25°C, 40°C, preferably 20-30°C; the time is 10-72h, for example, 15h, 30h, 50h, preferably 20-40h.

[0038] In step (2) of the present invention, the reducing agent is selected from at least one of ethylene, propylene, hydrogen, hydrazine hydrate, and formaldehyde, preferably at least one of hydrogen and hydrazine hydrate;

[0039] The amount of the reducing agent added is 0.5 to 20 times, such as 0.8 times, 5 times, 10 times, and preferably 1 to 15 times, the molar amount of the metal in the metal salt solution containing the active component in step (1).

[0040] In step (2) of the present invention, the reduction reaction is carried out at a temperature of 10 to 50°C, such as 15°C, 25°C, 40°C, preferably 20 to 30°C; and for a time of 5 to 40 hours, such as 15 hours, 30 hours, preferably 10 to 20 hours.

[0041] In step (2) of the present invention, the washing is water washing at a temperature of 20 to 50° C., for example, 30° C. or 40° C., until the filtrate is free of chloride ions;

[0042] The drying temperature is 100-150° C., and the drying time is 2-10 hours.

[0043] In step (3) of the present invention, the metal salt solution containing the co-active component is an aqueous solution with a concentration of 1 to 20 wt%, such as 3 wt%, 8 wt%, 15 wt%, preferably 5 to 10 wt%;

[0044] The co-active component is selected from at least one of alkali metal (such as Na, K, Se) acetates, preferably sodium acetate and / or potassium acetate;

[0045] The mass ratio of the precursor B to the aqueous solution containing the co-active component is 1:0.1-20, for example, 1:0.2, 1:1, 1:5, 1:15, preferably 1:0.3-10.

[0046] In step (3) of the present invention, the matrix is ​​selected from at least one of silica sol, graphene, and silicon powder, preferably at least one of graphene and silica sol;

[0047] The mass ratio of the matrix to the metal salt in the metal salt solution containing the co-active component is 1:0.1-5, preferably 1:0.2-3.

[0048] In step (3) of the present invention, the vacuum degree of the vacuum filtration is 0.05 to 0.08 MPa.

[0049] In step (3) of the present invention, the drying temperature is 100-150° C. and the drying time is 2-10 hours.

[0050] The allyl acetate catalyst provided by the present invention has a multi-stage "core-shell" structure, which can make the catalyst active component have a distribution in a suitable position, improve the overall thermal conductivity and diffusion performance of the catalyst, so that it has both excellent activity and selectivity. The matrix in the carrier, active component coating and co-active component coating with good thermal conductivity can greatly improve the thermal conductivity of the catalyst as a whole, avoid the product selectivity caused by the reaction heat being difficult to remove due to poor thermal conductivity, and catalyst stability and life span are poor. The carrier selected by the present invention has a suitable defect position, which is conducive to anchoring the active component during the preparation process and forming a more stable active component-carrier structure with it, and can also suppress the agglomeration of active components as a grain inhibitor, ensure that it is not easy to migrate and grow up and fall off while catalysis is exerted, causing the catalyst activity to decrease or the active component to be lost.

[0051] The active component metal can provide an active center to enable acetic acid, propylene and oxygen to undergo an oxyacylation reaction to generate allyl acetate. The addition of the ligand allows the active component to be tightly connected to the carrier and introduces a durable, conjugated macrocyclic linker to increase the specific surface area of ​​the catalyst. The alkyne group in the ligand can accommodate the active species and has a carrier function in addition to the framework. The addition of the ligand can excite oxygen during the reaction, reduce the heat of oxygen adsorption, and convert oxygen from gaseous oxygen (O2) to adsorbed oxygen (2O - ) and then rapidly converted into lattice oxygen (2O 2- ), which can react with acetic acid and propylene in the reaction to form allyl acetate at a lower reaction temperature; this reaction produces water, and the addition of the ligand can play a hydrophobic role, so that the water generated by the reaction can be quickly removed from the catalyst surface, allowing the reaction to proceed in the direction of forming allyl acetate, thereby improving the conversion rate and product selectivity, and at the same time preventing the active components and additives in the catalyst from being lost due to long-term residence in the water system environment.

[0052] The addition of co-active metal salts can better assist the active components to better exert their catalytic effect. The addition of the matrix in the active component and co-active component coating can better improve the dispersion of the active component and the co-active component, improve the thermal conductivity and catalyst activity, and help the catalyst have a longer service life.

[0053] The present invention also provides an application of the allyl acetate catalyst, which is suitable for synthesizing allyl acetate from acetic acid, oxygen and propylene.

[0054] Preferably, the present invention provides a method for preparing allyl acetate, comprising the steps of: using a fixed bed reactor, in the presence of the above-mentioned catalyst, mixing propylene, oxygen, acetic acid and water to react to prepare allyl acetate.

[0055] In the present invention, the molar ratio of propylene to oxygen, acetic acid, and water is 1:0.1 to 1:0.1 to 1:0.1 to 1, for example, 1:0.3:0.5:0.5;

[0056] In the present invention, the reaction temperature is 120-180°C, preferably 140-170°C; the pressure is 0.6-0.9 MPaG, preferably 0.7-0.8 MPaG; the reaction volume space velocity is 1500-2500h -1 , preferably 1800~2000h -1 .

[0057] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0058] The use of a carrier with suitable defect sites can firmly anchor the active components, preventing the migration, agglomeration, and loss of active components that lead to reduced catalyst activity; the addition of a matrix can improve the dispersion of active components and co-active components and enhance the thermal conductivity of the catalyst; the addition of a ligand allows the active components to be tightly connected to the carrier, increasing the specific surface area of ​​the catalyst, lowering the reaction temperature, rapidly stimulating the reaction, and improving conversion rate and selectivity;

[0059] The preparation method of thermal spray coating and vacuum filtration loading can ensure that the active components and co-active components in the catalyst are not easy to agglomerate and fall off during use, so as to avoid reducing the activity of the catalyst and causing economic loss.

[0060] The catalyst prepared by the present invention has the advantages of high dispersibility, high space-time yield, good thermal conductivity, high product selectivity, good stability, long catalyst life, etc., is suitable for synthesizing allyl acetate from acetic acid, oxygen and propylene, and improves economic efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 This is the active component distribution diagram of the catalyst prepared in Example 1;

[0062] Figure 2 This is the active component distribution diagram of the catalyst prepared in Comparative Example 1. DETAILED DESCRIPTION

[0063] In order to better illustrate the present invention, the present invention is further described below in conjunction with specific embodiments. However, the scope of the present invention is not limited to the scope of these embodiments.

[0064] The sources of the main raw materials used in the examples and comparative examples of the present invention are as follows. Unless otherwise specified, other reagents and raw materials are common commercial products:

[0065] Vanadium carbide: average particle size 5.0 mm, specific surface area 148.5 m 2 / g, pore volume 0.45cm 3 / g, average pore size 14.8mm, industrial grade, Hunan Huawei Jingcheng Material Technology Co., Ltd.;

[0066] Titanium nitride: average particle size 5.0 mm, specific surface area 149.5 m 2 / g, pore volume 0.45cm 3 / g, average pore size 14.5mm, industrial grade, Hunan Huawei Jingcheng Material Technology Co., Ltd.;

[0067] Titanium carbide: average particle size 5.0 mm, specific surface area 156.5 m 2 / g, pore volume 0.45cm 3 / g, average pore size 13.9mm, industrial grade, Hunan Huawei Jingcheng Material Technology Co., Ltd.;

[0068] Carbon nitride: average particle size 5.0 mm, specific surface area 146.5 m 2 / g, pore volume 0.45cm 3 / g, average pore size 15.2 mm, industrial grade, Beijing Huawei Ruike Chemical Co., Ltd.;

[0069] Graphene: industrial grade, Hengli Shengtai (Xiamen) Graphene Technology Co., Ltd.

[0070] Silica sol: industrial grade, Linyi Kehan ​​Silicon Products Co., Ltd.

[0071] The calculation methods and test methods used in the examples or comparative examples of the present invention are as follows:

[0072] 1. The content of each component in the reaction product was analyzed by gas chromatography (chromatograph: Agilent GC 8890A), and the activity and selectivity of the catalyst were calculated according to the following formula:

[0073] Catalyst activity (space-time yield of target product) = amount of allyl acetate produced / catalyst volume / reaction time, unit is g AAC / L Cat . / h;

[0074] Selectivity = (amount of allyl acetate produced / amount of propylene consumed in the reaction) × 100%;

[0075] Regarding the service life of the catalyst, the activity (STY value) of the catalyst is 300g AAC / Lcat. / h, the STY value is lower than 300, and it is generally believed that the catalyst activity does not meet the requirements for industrial use.

[0076] 2. Determination of specific surface area and pore structure information

[0077] The specific surface area, pore volume and pore size were determined by low-temperature liquid nitrogen physical absorption method. The specific surface area of ​​the sample was calculated based on BET theory, and the pore volume and pore size distribution were calculated using the t-plot BJH model. The testing instrument model was Micromeritics ASAP 2460.

[0078] 3. Thermal conductivity measurement method

[0079] Thermal conductivity is measured using the non-steady-state thermal conductivity test method, according to GB / T10297-2015. The test instrument model is KEM QTM-500.

[0080] 4. Distribution of active components of catalyst

[0081] The distribution of active components of the catalyst was observed and determined using a JEM2100Plus transmission electron microscope with a magnification scale of 20 nm.

[0082] 5. Adsorption heat determination method

[0083] The heat of gas adsorption on the catalyst was measured using a 3Flex gas adsorption instrument from Micromeritics Instruments.

[0084] 6. Method for determining particle strength

[0085] The particle strength is measured by pressure method, the detection basis is GB102012-88, and the test instrument model is FT-803.

[0086] Example 1

[0087] The steps for preparing a core-shell structured allyl acetate catalyst are as follows:

[0088] (1) Prepare 500 g of a mixed aqueous solution containing 13.8 g of sodium chloropalladate (including 5.0 g of Pd, 0.05 mol) and 10.6 g of copper chloride (including 5.0 g of Cu, 0.08 mol), add 25.0 g of hexachlorobenzene thereto, and after coordination reaction at 20°C for 20 h, add 10.0 g of graphene to prepare a coating liquid 1, and the coating liquid 1 is loaded on the surface of 500 g of carbon nitride by thermal spray coating at 120°C for 10 min to obtain a precursor A.

[0089] (2) Precursor A was added to a 10 wt% sodium silicate aqueous solution (including 0.13 mol of Na2SiO3) containing 15.9 g of sodium silicate, and the mixture was precipitated at 20°C for 20 h. Then, 6.3 g (0.13 mol) of hydrazine hydrate was added and mixed evenly. After the reduction reaction was carried out at 20°C for 10 h, the mixture was washed with warm water at 40°C until there was no chloride ion in the filtrate. After washing, the mixture was dried at 120°C for 5 h to obtain precursor B.

[0090] (3) 5.0 g of graphene was added to 72.2 g of 10 wt% cesium acetate aqueous solution to prepare a coating liquid 2, which was mixed with the precursor B and vacuum filtered at 0.05 MPa. After the filtration was completed, the mixture was dried at 120° C. for 5 h to obtain a core-shell structured allyl acetate catalyst 1 with uniformly anchored components. The catalyst structure is as follows: Figure 1 The thermal conductivity is shown in Table 1.

[0091] In catalyst 1 (active component distribution is as follows Figure 1 ), based on the mass of the carrier, the active component coating loading is 9.0wt%, of which the active component Pd content is 1.0wt%, the active component Cu content is 1.0wt%, the ligand hexachlorobenzene content is 5.0wt%, and the matrix graphene content is 2.0wt%. Based on the mass of the carrier, the co-active component coating loading is 2.4wt%, of which the co-active component cesium acetate content is 1.4wt%, and the matrix graphene content is 1.0wt%.

[0092] The particle size of catalyst 1 is 5.1 mm and the specific surface area is 168 m 2 / g, pore volume is 0.5cm 3 / g, and the pore size is 15.6nm.

[0093] Catalyst performance evaluation:

[0094] Allyl acetate was prepared by placing 500 mL of catalyst 1 into a fixed-bed reactor with an inner diameter of 40 mm and a height of 2000 mm, with inert porcelain balls packed at the upper and lower ends. The feed composition was a molar ratio of propylene: oxygen: acetic acid: water of 1:0.3:0.5:0.5, the reaction temperature was 140°C, the reaction pressure was 0.7 MPaG, and the reaction volume space velocity was 1800 h-1. -1 The reaction product was condensed and then chromatographically analyzed. The evaluation results are shown in Table 1.

[0095] Example 2

[0096] The steps for preparing a core-shell structured allyl acetate catalyst are as follows:

[0097] (1) Prepare 500 g of a mixed aqueous solution containing 52.1 g of zinc chloride (including 25.0 g of Zn, 0.38 mol) and 52.9 g of copper chloride (including 25.0 g of Cu, 0.39 mol), add 45.0 g of hexachlorobenzene thereto, and after coordination reaction at 30°C for 30 h, add 25.0 g of silica sol to prepare a coating liquid 1. The coating liquid 1 is loaded on the surface of 500 g of titanium carbide by thermal spray coating at 150°C for 20 min to obtain a precursor A.

[0098] (2) Precursor A was added to a 5 wt% sodium hydroxide aqueous solution (including 3.85 mol of NaOH) containing 154.0 g of sodium hydroxide, and the mixture was precipitated at 30° C. for 40 h. 385.5 g (7.7 mol) of hydrazine hydrate was then added and mixed evenly. After a reduction reaction at 30° C. for 20 h, the mixture was washed with warm water at 50° C. until no chloride ions were present in the filtrate. After washing, the mixture was dried at 150° C. for 10 h to obtain precursor B.

[0099] (3) 25.0 g of silica sol was added to 1781.5 g of a 5 wt% sodium acetate aqueous solution to prepare a coating liquid 2, which was mixed with the precursor B and vacuum filtered at 0.08 MPa. After the filtration was completed, the mixture was dried at 140° C. for 5 h to obtain a core-shell structured allyl acetate catalyst 2 with uniformly anchored components. The thermal conductivity is shown in Table 1.

[0100] In Catalyst 2, the active component coating loading was 24.0 wt% based on the mass of the carrier, including 5.0 wt% of the active component Zn, 5.0 wt% of the active component Cu, 9.0 wt% of the ligand hexachlorobenzene, and 5.0 wt% of the matrix silica sol. The co-active component coating loading was 22.8 wt% based on the mass of the carrier, including 17.8 wt% of the co-active component sodium acetate and 5.0 wt% of the matrix silica sol.

[0101] The particle size of catalyst 2 is 5.8 mm and the specific surface area is 222 m 2 / g, pore volume is 0.2cm 3 / g, pore size is 9.0nm.

[0102] Catalyst performance evaluation:

[0103] Allyl acetate was prepared by placing 500 mL of catalyst 2 in a fixed-bed reactor with an inner diameter of 40 mm and a height of 2000 mm, with inert porcelain balls at the upper and lower ends. The feed composition was a molar ratio of propylene: oxygen: acetic acid: water of 1:0.3:0.5:0.5, the reaction temperature was 130°C, the reaction pressure was 0.8 MPaG, and the reaction volume space velocity was 2000 h -1 The reaction product was condensed and then chromatographically analyzed. The evaluation results are shown in Table 1.

[0104] Example 3

[0105] The steps for preparing a core-shell structured allyl acetate catalyst are as follows:

[0106] (1) Prepare 500 g of a mixed aqueous solution containing 27.6 g of sodium chloropalladate (including 10.0 g of Pd, 0.09 mol) and 31.7 g of copper chloride (including 15.0 g of Cu, 0.24 mol), add 75.0 g of HHTP thereto, and after coordination reaction at 20°C for 40 h, add 10.0 g of silica sol to prepare a coating liquid 1. The coating liquid 1 is loaded on the surface of 500 g of vanadium carbide by thermal spray coating at 140°C for 10 min to obtain precursor A.

[0107] (2) Precursor A was added to a 10 wt% sodium hydroxide aqueous solution (including 0.66 mol of NaOH) containing 26.4 g of sodium hydroxide, and the mixture was precipitated at 20°C for 20 h. Then, 66.1 g (1.32 mol) of hydrazine hydrate was added and mixed evenly. After the reduction reaction was carried out at 20°C for 10 h, the mixture was washed with warm water at 40°C until there was no chloride ion in the filtrate. After washing, the mixture was dried at 120°C for 5 h to obtain precursor B.

[0108] (3) 15.0 g of silica sol was added to 376.1 g of a 10 wt% potassium acetate aqueous solution to prepare a coating liquid 2, which was mixed with the precursor B and vacuum filtered at 0.08 MPa. After the filtration was completed, the mixture was dried at 140° C. for 5 h to obtain a core-shell structured allyl acetate catalyst 3 with uniformly anchored components. The thermal conductivity is shown in Table 1.

[0109] In Catalyst 3, the active component coating loading was 22.0 wt% based on the mass of the support, including 2.0 wt% of the active component Pd, 3.0 wt% of the active component Cu, 15.0 wt% of the ligand HHTP, and 2.0 wt% of the matrix silica sol. The co-active component coating loading was 10.5 wt% based on the mass of the support, including 7.5 wt% of the co-active component potassium acetate and 3.0 wt% of the matrix silica sol.

[0110] The particle size of catalyst 3 is 5.7 mm and the specific surface area is 208 m 2 / g, pore volume is 0.25cm 3 / g, pore size is 10.1nm.

[0111] Catalyst performance evaluation:

[0112] Allyl acetate was prepared by placing 500 mL of catalyst 3 in a fixed-bed reactor with an inner diameter of 40 mm and a height of 2000 mm, with inert porcelain balls at the upper and lower ends. The feed composition was a molar ratio of propylene: oxygen: acetic acid: water of 1:0.3:0.5:0.5, the reaction temperature was 120°C, the reaction pressure was 0.7 MPaG, and the reaction volume space velocity was 1800 h -1 The reaction product was condensed and then chromatographically analyzed. The evaluation results are shown in Table 1.

[0113] Example 4

[0114] The steps for preparing a core-shell structured allyl acetate catalyst are as follows:

[0115] (1) Prepare 500 g of a mixed aqueous solution containing 27.6 g of sodium chloropalladate (including 10.0 g of Pd, 0.09 mol) and 69.0 g of chloroauric acid (including 40.0 g of Au, 0.20 mol), add 60.0 g of HHTP thereto, and after coordination reaction at 30°C for 30 h, add 10.0 g of silica sol to prepare coating liquid 1. The coating liquid 1 is loaded on the surface of 500 g of vanadium carbide by thermal spray coating at 140°C for 20 min to obtain precursor A.

[0116] (2) Precursor A was added to a 1 wt% sodium carbonate aqueous solution (including 0.29 mol of Na2CO3) containing 30.7 g of sodium carbonate, and the mixture was precipitated at 20°C for 20 h. Then, 66.1 g (1.32 mol) of hydrazine hydrate was added and mixed evenly. After the reduction reaction was carried out at 20°C for 10 h, the mixture was washed with warm water at 40°C until there was no chloride ion in the filtrate. After washing, the mixture was dried at 120°C for 5 h to obtain precursor B.

[0117] (3) 5.0 g of graphene was added to 125.4 g of a 10 wt% potassium acetate aqueous solution to prepare a coating liquid 2, which was mixed with the precursor B and vacuum filtered at 0.08 MPa. After the filtration was completed, the mixture was dried at 140° C. for 5 h to obtain a core-shell structured allyl acetate catalyst 4 with uniformly anchored components. The thermal conductivity coefficient is shown in Table 1.

[0118] In Catalyst 4, the active component coating loading was 24.0 wt% based on the mass of the carrier, including 2.0 wt% of the active component Pd, 8.0 wt% of the active component Au, 12.0 wt% of the ligand HHTP, and 2.0 wt% of the matrix silica sol. The co-active component coating loading was 3.5 wt% based on the mass of the carrier, including 2.5 wt% of the co-active component potassium acetate and 1.0 wt% of the matrix graphene.

[0119] The particle size of catalyst 4 is 5.9 mm and the specific surface area is 263 m 2 / g, pore volume is 0.26cm 3 / g, pore size is 9.1nm.

[0120] Catalyst performance evaluation:

[0121] Preparation of allyl acetate: 500 mL of catalyst 4 was placed in a fixed-bed reactor with an inner diameter of 40 mm and a height of 2000 mm. Inert porcelain balls were placed at the upper and lower ends. The feed composition was a molar ratio of propylene: oxygen: acetic acid: water of 1:0.3:0.5:0.5. The reaction temperature was 135°C, the reaction pressure was 0.7 MPaG, and the reaction volume space velocity was 1800 h-1. -1 The reaction product was condensed and then chromatographically analyzed. The evaluation results are shown in Table 1.

[0122] Example 5

[0123] The steps for preparing a core-shell structured allyl acetate catalyst are as follows:

[0124] (1) Prepare 500 g of a mixed aqueous solution containing 41.5 g of sodium chloropalladate (including 15.0 g of Pd, 0.14 mol) and 73.0 g of zinc chloride (including 35.0 g of Zn, 0.54 mol), add 30.0 g of hexachlorobenzene thereto, and after coordination reaction at 20°C for 20 h, add 15.0 g of silicon powder to prepare a coating liquid 1, and the coating liquid 1 is loaded on the surface of 500 g of titanium nitride by thermal spray coating at 120°C for 15 min to obtain a precursor A.

[0125] (2) Precursor A was added to a 10 wt% sodium hydroxide aqueous solution (including 2.04 mol of NaOH) containing 81.6 g of sodium hydroxide, and the mixture was precipitated at 20°C for 20 h. Then, 66.1 g (1.32 mol) of hydrazine hydrate was added and mixed evenly. After the reduction reaction was carried out at 20°C for 10 h, the mixture was washed with warm water at 40°C until there was no chloride ion in the filtrate. After washing, the mixture was dried at 120°C for 5 h to obtain precursor B.

[0126] (3) 9.0 g of silicon powder was added to 225.7 g of a 10 wt% potassium acetate aqueous solution to prepare a coating liquid 2, which was mixed with the precursor B and vacuum filtered at 0.07 MPa. After the filtration was completed, the mixture was dried at 140° C. for 5 h to obtain a core-shell structured allyl acetate catalyst 5 with uniformly anchored components. The thermal conductivity is shown in Table 1.

[0127] In Catalyst 5, the active component coating loading was 19.0 wt% based on the mass of the carrier, including 3.0 wt% of the active component Pd, 7.0 wt% of the active component Zn, 6.0 wt% of the ligand hexachlorobenzene, and 3.0 wt% of the matrix silicon powder. The co-active component coating loading was 6.3 wt% based on the mass of the carrier, including 4.5 wt% of the co-active component potassium acetate and 1.8 wt% of the matrix silicon powder.

[0128] The particle size of catalyst 5 is 5.5 mm and the specific surface area is 153 m 2 / g, pore volume is 0.32cm 3 / g, and the pore size is 12.6nm.

[0129] Catalyst performance evaluation:

[0130] Preparation of allyl acetate: 500 mL of catalyst 5 was placed in a fixed-bed reactor with an inner diameter of 40 mm and a height of 2000 mm. Inert porcelain balls were placed at the upper and lower ends. The feed composition was a molar ratio of propylene: oxygen: acetic acid: water of 1:0.3:0.5:0.5. The reaction temperature was 140°C, the reaction pressure was 0.8 MPaG, and the reaction volume space velocity was 1900 h-1. -1 The reaction product was condensed and then chromatographically analyzed. The evaluation results are shown in Table 1.

[0131] Comparative Example 1

[0132] The allyl acetate catalyst was prepared by referring to the method of Example 1, except that the carbon nitride in step (1) was replaced with silica gel balls, the evaluation temperature was 145°C, and the other operations and conditions remained unchanged to obtain a catalyst (active component distribution as shown in FIG. Figure 2 ), the performance evaluation results are shown in Table 1.

[0133] Comparative Example 2

[0134] The allyl acetate catalyst was prepared according to the method of Example 1, except that in step (2), the precursor B was directly added to the coating liquid 2 without vacuum filtration, the evaluation temperature was 150°C, and the other operations and conditions remained unchanged. The catalyst was prepared, and the performance evaluation results are shown in Table 1.

[0135] Comparative Example 3

[0136] An allyl acetate catalyst was prepared by referring to the method of Example 1, except that cesium acetate was replaced by calcium acetate in step (2), the evaluation temperature was 150° C., and other operations and conditions remained unchanged. The catalyst was prepared, and the performance evaluation results are shown in Table 1.

[0137] Comparative Example 4

[0138] The allyl acetate catalyst was prepared by referring to the method of Example 1, except that cesium acetate was replaced with potassium nitrate in step (2). Other operations and conditions remained unchanged to obtain the catalyst. The performance evaluation results are shown in Table 1.

[0139] Comparative Example 5

[0140] The allyl acetate catalyst was prepared according to the method of Example 1, except that no ligand was added in step (1), the coating liquid 1 was prepared directly, the evaluation temperature was 160°C, and other operations and conditions remained unchanged. The catalyst was prepared, and the performance evaluation results are shown in Table 1.

[0141] Comparative Example 6

[0142] The allyl acetate catalyst was prepared by referring to the method of Example 1, except that the ligand in step (1) was replaced with 2,3,6,7,10,11-hexahydroxytriphenylene. Other operations and conditions remained unchanged to obtain the catalyst. The performance evaluation results are shown in Table 1.

[0143] Comparative Example 7

[0144] An allyl acetate catalyst was prepared by referring to the method of Example 1, except that no matrix graphene was added in step (1) and step (3), the evaluation temperature was 145° C., and other operations and conditions remained unchanged. The catalyst was prepared, and the performance evaluation results are shown in Table 1.

[0145] Comparative Example 8

[0146] The allyl acetate catalyst was prepared according to the method of Example 1, except that the support was replaced with silica gel balls in step (1), the evaluation temperature was 155° C., and other operations and conditions remained unchanged. The catalyst was prepared, and the performance evaluation results are shown in Table 1.

[0147] Comparative Example 9

[0148] The allyl acetate catalyst was prepared by referring to the method of Example 1, except that in step (1), the coating liquid 1 was loaded on the carrier by impregnation. Other operations and conditions remained unchanged to obtain the catalyst. The performance evaluation results are shown in Table 1.

[0149] Comparative Example 10

[0150] The allyl acetate catalyst was prepared according to the method of Example 1, except that in step (3), the coating liquid 2 was loaded on the carrier by impregnation. Other operations and conditions remained unchanged to obtain the catalyst. The performance evaluation results are shown in Table 1.

[0151] Table 1 Evaluation results of initial activity and life of different catalysts

[0152]

[0153] Depend on Figure 1 The data show that this method is used to prepare a solution containing the metal salt of the active component and react it with the ligand, and then prepare a coating liquid with the matrix and load it on the carrier through thermal spray coating. After precipitation, aging and reduction, the coating liquid prepared by the auxiliary metal salt solution and the matrix is ​​loaded on the reduced precursor through vacuum filtration. The obtained catalyst has a multi-level "core-shell" structure and can evenly disperse the active components and anchor them on the carrier.

[0154] From the data in Table 1, it can be seen that the catalyst prepared by the present invention has the characteristics of high dispersion of active components, low activation temperature, high space-time yield, good thermal conductivity, high product selectivity, good stability, and long catalyst life, and is suitable for the synthesis of allyl acetate from acetic acid, oxygen and propylene.

Claims

1. A core-shell structure allyl acetate catalyst, characterized in that: The catalyst comprises a carrier core, and an active component coating and a co-active component coating sequentially coated on the outer surface of the carrier; The carrier is selected from at least one of titanium nitride, carbon nitride, vanadium carbide, and titanium carbide; The active component coating comprises an active metal, a ligand and a matrix, wherein the active metal is selected from at least one of metals Pd, Pt, Au, Cu and Zn; the ligand is selected from at least one of 2,3,8,9,14,15-hexahydroxytriphenylcycloalkyne and hexachlorobenzene; and the matrix is ​​selected from at least one of silica sol, graphene and silicon powder. The auxiliary active component coating comprises an auxiliary active metal salt and a matrix, wherein the auxiliary active metal salt is selected from at least one of alkali metal acetates; and the matrix is ​​selected from at least one of silica sol, graphene, and silicon powder; The active component is formed into a single metal atom by thermal spray coating, precipitation and reduction, and loaded on the surface of the carrier; the co-active component is loaded by vacuum filtration deposition; The active component coating loading is 0.2 to 25.0 wt%, based on the mass of the carrier; In the active component coating, based on the mass of the carrier, the active metal content is 0.1 to 10 wt%, the ligand content is 1.0 to 20.0 wt%, and the matrix content is 0.1 to 10 wt%; The loading amount of the co-active component coating is 0.2 to 25.0 wt % based on the mass of the carrier; In the co-active component coating, based on the mass of the carrier, the content of the co-active metal salt is 0.1 to 20 wt %; and the content of the matrix is ​​0.1 to 10.0 wt %.

2. The core-shell structure allyl acetate catalyst according to claim 1, characterized in that The co-active metal salt is sodium acetate and / or potassium acetate.

3. The core-shell structure allyl acetate catalyst according to claim 1, characterized in that In the active component coating, based on the mass of the carrier, the active metal content is 1 to 10 wt%, the ligand content is 5.0 to 15.0 wt%, and the matrix content is 1 to 10 wt%.

4. The core-shell structured allyl acetate catalyst according to claim 1, characterized in that In the co-active component coating, based on the mass of the carrier, the content of the co-active metal salt is 1 to 15.0 wt%; and the content of the matrix is ​​1.0 to 5.0 wt%.

5. The core-shell structured allyl acetate catalyst according to claim 1, characterized in that: Particle size is 2-9 mm; specific surface area is 30-350 m 2 / g; pore volume is 0.1~1.0cm 3 / g; pore diameter is 5~25nm.

6. The core-shell structured allyl acetate catalyst according to claim 5, characterized in that: Particle size is 4-6 mm; specific surface area is 50-250 m 2 / g; pore volume is 0.2~0.7cm 3 / g; pore diameter is 8~20nm.

7. A method for preparing the core-shell structured allyl acetate catalyst according to any one of claims 1 to 6, characterized in that the steps include: (1) A metal salt solution containing an active component is mixed with a ligand to undergo a coordination reaction, and then a matrix is ​​added to the mixture to obtain a coating liquid 1, which is then thermally sprayed onto a support surface to obtain a precursor A; (2) adding the precursor A obtained in step (1) to an aqueous solution of a precipitant to carry out a precipitation reaction, then adding a reducing agent to carry out a reduction reaction, and washing and drying to obtain a precursor B; (3) The metal salt solution containing the auxiliary active component is mixed with the matrix to obtain a coating liquid 2, and the coating liquid 2 is deposited on the surface of the precursor B by vacuum filtration, and dried to obtain a core-shell structured allyl acetate catalyst.

8. The preparation method according to claim 7, characterized in that In step (1), the metal salt solution containing the active component is an aqueous solution with a concentration of 5 to 30 wt%; The metal salt containing the active component is selected from at least one of the chlorides, nitrates and acetates of Pd, Pt, Au, Cu and Zn; In step (1), the ligand is selected from at least one of 2,3,8,9,14,15-hexahydroxytriphenylcycloalkyne and hexachlorobenzene; The mass ratio of the ligand to the metal in the metal salt solution containing the active component is 1:0.1-10; In step (1), the matrix is ​​selected from at least one of silica sol, graphene, and silicon powder; The mass ratio of the matrix to the metal in the metal salt solution containing the active component is 1:0.1-5; In step (1), the carrier is selected from at least one of titanium nitride, carbon nitride, vanadium carbide, and titanium carbide; The mass ratio of the carrier to the metal salt containing the active component in the metal salt solution containing the active component is 1 to 100:

1.

9. The preparation method according to claim 8, characterized in that The metal salt solution containing the active component is an aqueous solution with a concentration of 10-20 wt%.

10. The preparation method according to claim 8, characterized in that The mass ratio of the ligand dosage to the metal in the metal salt solution containing the active component is 1:0.5-5.

11. The preparation method according to claim 8, characterized in that The mass ratio of the matrix dosage to the metal in the metal salt solution containing the active component is 1:0.2-3.

12. The preparation method according to claim 8, characterized in that The mass ratio of the carrier to the metal salt containing the active component in the metal salt solution containing the active component is 2 to 50:

1.

13. The preparation method according to claim 7, characterized in that In step (1), the coordination reaction is carried out at a temperature of 10 to 50° C. and for a time of 10 to 72 hours; In step (1), the thermal spray coating temperature is 100-200° C., and the time is 5-30 minutes.

14. The preparation method according to claim 13, characterized in that The coordination reaction has a temperature of 20 to 30° C. and a time of 20 to 40 hours.

15. The preparation method according to claim 13, characterized in that The thermal spray coating temperature is 120-150° C., and the time is 10-20 minutes.

16. The preparation method according to claim 7, characterized in that In step (2), the aqueous solution of the precipitant has a concentration of 1 to 20 wt%; The precipitant is selected from at least one of potassium hydroxide, sodium hydroxide, potassium carbonate, sodium carbonate, potassium silicate, and sodium silicate; The aqueous solution of the precipitant is used in an amount, based on the precipitant, of 1 to 20 times the molar amount of the metal in the metal salt solution containing the active component in step (1); In step (2), the precipitation reaction is carried out at a temperature of 10 to 50° C. and for a time of 10 to 72 hours.

17. The preparation method according to claim 16, characterized in that The aqueous solution of the precipitant has a concentration of 5 to 10 wt%.

18. The preparation method according to claim 16, characterized in that The amount of the aqueous solution of the precipitant, calculated based on the precipitant, is 1 to 5 times the molar amount of the metal in the metal salt solution containing the active component in step (1).

19. The preparation method according to claim 16, characterized in that The precipitation reaction is carried out at a temperature of 20 to 30° C. and for a time of 20 to 40 hours.

20. The preparation method according to claim 7, characterized in that In step (2), the reducing agent is selected from at least one of ethylene, propylene, hydrogen, hydrazine hydrate, and formaldehyde; The amount of the reducing agent added is 0.5 to 20 times the molar amount of the metal in the metal salt solution containing the active component in step (1); In step (2), the reduction reaction is carried out at a temperature of 10 to 50° C. and for a time of 5 to 40 hours; In step (2), the washing is water washing at a temperature of 20 to 50° C., and the washing is performed until the filtrate is free of chloride ions; The drying temperature is 100-150° C., and the drying time is 2-10 hours.

21. The preparation method according to claim 20, characterized in that The amount of the reducing agent added is 1 to 15 times the molar amount of the metal in the metal salt solution containing the active component in step (1).

22. The preparation method according to claim 20, characterized in that The reduction reaction is carried out at a temperature of 20 to 30° C. and for a time of 10 to 20 hours.

23. The preparation method according to claim 7, characterized in that In step (3), the metal salt solution containing the co-active component is an aqueous solution with a concentration of 5 to 30 wt%; The co-active component is selected from at least one of alkali metal acetates; The mass ratio of the precursor B to the aqueous solution containing the co-active component is 1:0.1-20; In step (3), the matrix is ​​selected from at least one of silica sol, graphene, and silicon powder; The mass ratio of the matrix to the metal salt in the metal salt solution containing the co-active component is 1:0.1-5; In step (3), the vacuum degree of the vacuum filtration is 0.05 to 0.08 MPa; In step (3), the drying temperature is 100-150° C. and the drying time is 2-10 hours.

24. The preparation method according to claim 23, characterized in that The metal salt solution containing the co-active component is an aqueous solution with a concentration of 10-20 wt%.

25. The preparation method according to claim 23, characterized in that The co-active component is selected from sodium acetate and / or potassium acetate.

26. The preparation method according to claim 23, characterized in that The mass ratio of the precursor B to the aqueous solution containing the co-active component is 1:0.3-10.

27. The preparation method according to claim 23, characterized in that The mass ratio of the matrix to the metal salt in the metal salt solution containing the auxiliary active component is 1:0.2-3.

28. A method for preparing allyl acetate, characterized in that: The steps include: Using a fixed bed reactor, in the presence of the core-shell structured allyl acetate catalyst according to any one of claims 1 to 6 or the core-shell structured allyl acetate catalyst prepared by the method according to any one of claims 7 to 27, propylene, oxygen, acetic acid, and water are mixed and reacted to prepare allyl acetate; The molar ratio of propylene to oxygen, acetic acid and water is 1:0.1-1:0.1-1:0.1-1; The reaction temperature is 120-180°C, the pressure is 0.6-0.9 MPaG, and the reaction volume space velocity is 1500-2500 h -1 .

29. The preparation method according to claim 28, characterized in that The reaction temperature is 140-170° C. and the pressure is 0.7-0.8 MPaG.

30. The preparation method according to claim 28, characterized in that The reaction volume space velocity is 1800~2000h -1 .

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