Catalyst for isomerization of propylene oxide to allyl alcohol in fixed bed single tube reactor and preparation and application thereof

Abstract

The application provides a catalyst for preparing allyl alcohol by isomerization of propylene oxide in a fixed bed single tube reactor and a preparation method thereof, and belongs to the fields of catalyst preparation technology and chemical technology. The catalyst comprises an inert porous carrier material, and a layer of catalyst components containing a phosphate metal and a binder is coated on the carrier. The preparation process of the catalyst is as follows: slurry is prepared, the viscosity of the catalyst active material slurry is controlled, the carrier is heated, the slurry is sprayed onto the catalyst carrier in a rotating drum, and hot air is used for drying. The prepared catalyst is applied to the preparation of allyl alcohol by catalyzing the isomerization of propylene oxide in a fixed bed single tube reactor.

Description

Technical Field

[0001] This invention relates to a catalyst for the isomerization of propylene oxide to allyl alcohol in a fixed-bed single-tube reactor and its preparation method, belonging to the fields of catalyst preparation technology and chemical technology. Background Technology

[0002] Allyl alcohols are an important class of chemical intermediates and fine chemical products. Because their molecular structure contains both carbon-carbon double bonds and hydroxyl groups, allyl alcohols can react with compounds such as ethers, esters, and aldehydes. Many widely used downstream products can be synthesized from allyl alcohols; therefore, they are indispensable intermediate raw materials in the fine chemical industry, especially in pharmaceuticals, fragrances, and surfactants.

[0003] Common industrial synthesis methods for allyl alcohol include allyl chloride hydrolysis (saponification), acrolein reduction, propylene oxide isomerization, and propylene acetate hydrolysis. Allyl chloride hydrolysis is the earliest industrial method for producing allyl alcohol. Allyl chloride is saponified to produce allyl alcohol with a yield of 85%-95%, while generating 5%-10% byproducts. This method uses propylene as a starting material, first chlorinating it at high temperature to obtain allyl chloride, producing a large amount of HCl as a byproduct; then, allyl chloride undergoes saponification to produce allyl alcohol, producing a large amount of NaCl as a byproduct. Allyl aldehyde reduction is an intermediate step in the synthesis of glycerol from allyl aldehyde. Under the action of a catalyst, propylene is first oxidized to allyl aldehyde, which is then hydrogen-exchanged with ethanol or isopropanol to obtain allyl alcohol. The advantage of this method is that it does not require chlorine and has lower production costs; however, the separation and purification of allyl aldehyde is complex, and the equipment investment cost is high, making it only suitable for large-scale production. The propylene oxide isomerization method, adopted in the 1990s, involves the liquid- or gas-phase isomerization of propylene oxide to obtain allyl alcohol. Due to its simplicity, lack of equipment corrosion, and compliance with green chemistry requirements, the gas-phase method is currently more favored for allyl alcohol production both domestically and internationally. The gas-phase production of allyl alcohol primarily involves the vaporization and preheating of propylene oxide, followed by isomerization into allyl alcohol under the action of a lithium phosphate catalyst. To date, the reaction for the isomerization of propylene oxide to synthesize allyl alcohol remains primarily at the laboratory level, and mature industrial-scale technology is not yet available in China. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, the present invention aims to provide a catalyst for the isomerization of propylene oxide to allyl alcohol in a fixed-bed single-tube reactor and a method for its preparation. The catalyst is industrially applicable and can be used in a fixed-bed single-tube reactor; by improving the dispersion state of the catalyst, the production efficiency of allyl alcohol is increased.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows:

[0006] A catalyst for the isomerization of propylene oxide to prepare allyl alcohol in a fixed-bed single-tube reactor comprises an inert porous support material, on which a layer of catalyst active components containing phosphate metals and binders is coated.

[0007] In the catalyst active component

[0008] The sum of the mass of lithium phosphate and binder in the active component layer is 5-50% (preferably 10-30%, more preferably 20-30%) of the carrier mass;

[0009] The mass ratio of lithium phosphate to binder in the active component layer is 10:1-1:1 (preferably 10:1-4:1, more preferably 9:1-5:1).

[0010] The inert porous carrier with a pore size range of 2-50 nanometers is at least one or more of alumina, aluminum silicate, ceramic, and silica gel.

[0011] The inert porous carrier is at least one or more of the following: spherical particles with a diameter of 1-3 mm, annular particles with an outer diameter of 1-3 mm and an inner diameter of 0.5-1 mm, or cylindrical particles with a diameter of 1-3 mm and a height of 2-5 mm.

[0012] The preparation method of the catalyst for the isomerization of propylene oxide to allyl alcohol in the fixed-bed single-tube reactor is carried out according to the following steps:

[0013] (1) Preparation of slurry: According to the formulation ratio of the catalyst, lithium phosphate and an appropriate amount of binder are added to a ball mill or colloid mill, ground, mixed and emulsified to make a suspension, wherein the solid content is in the range of 50-90% (preferably 70-90%), and a catalyst active material slurry is obtained.

[0014] (2) Heating the carrier: The carrier is placed in the drum of a coating machine, and hot air is used to heat the carrier to 100-200℃ (preferably 100-150℃); (3) Spraying and drying: The catalyst active material slurry prepared in step 1 is atomized through a nozzle and sprayed onto the carrier inside the drum. At the same time, hot air is blown into the drum to control the carrier temperature at 80-150℃ (preferably 80-120℃), so that the catalyst active material sprayed on the surface of the carrier dries rapidly to form a catalyst active material coating. The spraying time is controlled until the content of the catalyst active material coating reaches 5-50% of the carrier mass, and then the spraying is stopped; the catalyst is obtained.

[0015] The adhesive is at least two of vinyl acetate, acrylate, and maleic acid ester;

[0016] The method for preparing allyl alcohol by isomerization of propylene oxide in a fixed-bed single-tube reactor involves placing the catalyst in the fixed-bed single-tube reactor, controlling the reactor temperature at 300–500°C under a nitrogen atmosphere, and treating it at this temperature for 1–5 hours. Then, propylene oxide is preheated to 30–80°C (preferably 30–50°C) and pumped into the fixed-bed reactor, using nitrogen as the carrier gas. The reactor temperature is controlled at 250–400°C (preferably 280–320°C), and the reaction is carried out at this temperature. The product is condensed in an ice-water bath and then analyzed by gas chromatography.

[0017] The inner diameter of the fixed-bed single-tube reactor is 5mm-50mm (preferably 8mm-15mm); the height of the single-tube reactor is 200mm-3000mm.

[0018] The mass hourly space velocity of the propylene oxide is 10–20 h⁻¹. -1 (Preferred time: 10-15 hours) -1 The flow rate of nitrogen is 5-50 mL / min (preferably 5-30 mL / min).

[0019] The catalyst comprises an inert, porous support material, on which a layer of catalyst components containing phosphate metals and binders is coated. The catalyst preparation process involves first preparing a slurry and controlling the viscosity of the catalyst active material slurry, heating the support, spraying the slurry onto the catalyst support in a rotating drum, and then drying it with hot air. The prepared catalyst is used in a fixed-bed single-tube reactor for the catalytic isomerization of propylene oxide to allyl alcohol.

[0020] The beneficial effects of the present invention include, but are not limited to:

[0021] (1) The catalyst provided by this invention is in the form of industrial application. It is used in a fixed-bed single-tube reactor to catalyze the isomerization of propylene oxide to prepare allyl alcohol. The reaction process has a small scale-up effect and is easy to realize industrial application.

[0022] (2) The catalyst provided by this invention has high stability and long service life. Because the catalyst is uniformly coated on the surface of the porous support, the efficiency of the catalyst is improved, carbon deposition on the catalyst surface is effectively suppressed, and the service life of the catalyst is extended.

[0023] (3) The method for preparing allyl alcohol by isomerization of propylene oxide provided by the present invention is simple to operate, meets the requirements of industrial production, and is convenient for large-scale industrial production. Detailed Implementation

[0024] The following embodiments are merely illustrative of the present invention, but the invention is not limited to these embodiments. Furthermore, the embodiments only provide some conditions for the preparation of allyl alcohol, and do not imply that these conditions must be met to achieve this objective. Any structures similar to those of the present invention and similar variations thereof are included within the scope of protection of the present invention.

[0025] The lithium phosphate catalyst in the examples was prepared according to the co-precipitation method described in the published literature.

[0026] Example

[0027] Catalyst powder preparation:

[0028] 380g of sodium phosphate dodecahydrate was dissolved in 1000mL of water to prepare an aqueous sodium phosphate solution. 40g of sodium hydroxide and 120g of lithium hydroxide monohydrate were dissolved in 1000mL of water to obtain an alkaline lithium hydroxide solution. The aqueous sodium phosphate solution was added to a three-necked flask, and lithium hydroxide solution was added dropwise to the sodium phosphate solution at 60℃ over 2 hours. After the addition was completed, this temperature was maintained to allow the precipitate to mature for 2 hours. The mixture was then filtered and washed with deionized water until the pH reached 12. The resulting white solid powder was dried in a vacuum drying oven at 120℃ for 6 hours and then calcined in air at 320℃ for 8 hours to obtain a lithium phosphate catalyst.

[0029] Catalyst spraying:

[0030] 120g of the prepared lithium phosphate catalyst and 20g of vinyl acetate were mixed with water to achieve a solid content of 80%, and then ground in a ball mill for 4 hours to emulsify the mixture into a uniform suspension. The resulting suspension was added to the feed tank of a spraying equipment and stirred. 500g of silica gel spheres with a diameter of 2mm (pore size 2-50 nm) were placed in the drum of a coating machine (Changzhou Lima Drying Engineering Co., Ltd., GPX series small spray dryer). The carrier was heated and dried by turning on hot air. When the temperature of the carrier reached 120℃, the feed nozzle was turned on, and the suspension of catalytic active material was sprayed onto the surface of the carrier. After rapid drying by hot air, the carrier temperature was controlled at 120℃. By controlling the spraying time, the content of catalytic active material (lithium phosphate catalyst and vinyl acetate) was controlled to reach 5% of the carrier mass. Spraying was then stopped, and the catalyst was obtained.

[0031] Catalyst activity evaluation:

[0032] The prepared catalyst was added to a fixed-bed single-tube reactor for activity evaluation. The single-tube reactor used had an inner diameter of 45 mm and a tube length of 2000 mm. A forced-circulation molten salt was used as the heat exchanger outside the reactor tube. The catalyst loading was 2.0 L, and the reactor was treated at 400 °C for 3 h under a nitrogen flow rate of 10 mL / min. Propylene oxide, preheated to 30 °C, was pumped into the fixed-bed reactor. Nitrogen was used as the carrier gas at a flow rate of 10 mL / min. The reactor temperature was controlled at 300 °C, 250 °C, and 400 °C, and the mass hourly space velocity (HSV) of propylene oxide was 15 h⁻¹. -1 The reaction products are condensed in an ice-water bath and collected in a product container. A sampling port is set at the lower end of the reaction tube, and the products are analyzed by gas chromatography.

[0033] Comparative Example

[0034] Catalyst powder preparation:

[0035] 380g of sodium phosphate dodecahydrate was dissolved in 1000mL of water to prepare an aqueous sodium phosphate solution. 40g of sodium hydroxide and 120g of lithium hydroxide monohydrate were dissolved in 1000mL of water to obtain an alkaline lithium hydroxide solution. The aqueous sodium phosphate solution was added to a three-necked flask, and lithium hydroxide solution was added dropwise to the sodium phosphate solution at 60℃ over 2 hours. After the addition was completed, this temperature was maintained to allow the precipitate to mature for 2 hours. The mixture was then filtered and washed with deionized water until the pH reached 12. The resulting white solid powder was dried in a vacuum drying oven at 120℃ for 6 hours and then calcined in air at 320℃ for 8 hours to obtain a lithium phosphate catalyst.

[0036] Catalyst activity evaluation:

[0037] The prepared lithium phosphate catalyst was pressed into tablets and sieved to 10-20 mesh, then added to a fixed-bed single-tube reactor for activity evaluation. The single-tube reactor used had an inner diameter of 45 mm and a tube length of 2000 mm, with a forced-circulation molten salt as the heat exchanger outside the reactor tube. The catalyst loading was 2.0 L, and the reactor was treated at 400 °C for 3 h under a nitrogen flow rate of 10 mL / min. Propylene oxide, preheated to 30 °C, was pumped into the fixed-bed reactor. Nitrogen was used as the carrier gas at a flow rate of 10 mL / min, and the reactor temperature was controlled at 300 °C. The mass hourly space velocity (MSV) of propylene oxide was 15 h⁻¹. -1 The reaction products were condensed in an ice-water bath and collected in a product container, where they were analyzed by gas chromatography.

[0038] Product analyses in the examples and comparative examples were performed on an Agilent 7890A chromatograph equipped with an HP-5 (30 m × 0.320 mm × 0.25 μm) capillary column and an FID flame ionization detector. The conversion rate X of propylene oxide was... PO Selectivity of allyl alcohol AAThe definition is as follows:

[0039] X PO =(n / n PO )×100% (1)

[0040] S AA =(n AA / n PO (2) × 100%

[0041] Where: n——the total amount of propylene oxide reacted, in mol;

[0042] n0—Injection volume of propylene oxide, in mol;

[0043] n AA —Amount of allyl alcohol in the product, in mol.

[0044] Table 1

[0045]

[0046]

[0047] This invention is not limited to the examples described herein, which are illustrative and not restrictive. The scope of this invention is defined by the claims. Any modifications, rearrangements, or other techniques related to this invention made by those skilled in the art based on this invention are within the protection scope of this invention.

Claims

1. A catalyst for the isomerization of propylene oxide to prepare allyl alcohol in a fixed-bed single-tube reactor, characterized in that: It includes an inert porous support material and a catalyst active component layer covered on the support, consisting of a layer of lithium phosphate and a binder; In the catalyst active component The sum of the mass of lithium phosphate and binder in the active component layer is 5-50% (preferably 10-30%, more preferably 20-30%) of the carrier mass; The mass ratio of lithium phosphate to binder in the active component layer is 10:1-1:1 (preferably 10:1-4:1, more preferably 9:1-5:1).

2. The catalyst according to claim 1, characterized in that: The inert porous carrier with a pore size range of 2-50 nanometers is at least one or more of alumina, aluminum silicate, ceramic, and silica gel.

3. The catalyst according to claim 1 or 2, characterized in that: The inert porous carrier is at least one or more of the following: spherical particles with a diameter of 1-3 mm, annular particles with an outer diameter of 1-3 mm, an inner diameter of 0.5-1 mm, and a height of 2-5 mm, or cylindrical particles with a diameter of 1-3 mm and a height of 2-5 mm.

4. The catalyst according to claim 1, characterized in that: The adhesive is at least one or more of vinyl acetate, acrylate, and maleic acid ester.

5. A method for preparing the catalyst according to any one of claims 1-4 for the isomerization of propylene oxide to allyl alcohol in a fixed-bed single-tube reactor, characterized in that, Follow these steps: (1) Preparation of slurry: According to the formulation ratio of the catalyst, lithium phosphate, binder and water are added to a ball mill or colloid mill, ground, mixed and emulsified to make a suspension, wherein the solid content is in the range of 50-90% (preferably 70-90%), and a catalyst active material slurry is obtained. (2) Heating the carrier: The carrier is placed in the drum of the coating machine and heated to 100-200℃ (preferably 100-150℃) with hot air; (3) Spraying and drying: The catalyst active material slurry prepared in step (1) is atomized through a nozzle and sprayed onto the carrier inside the rotating drum. At the same time, hot air is blown into the rotating drum to control the carrier temperature at 80-150℃ (preferably 80-120℃) so that the catalyst active material sprayed on the carrier surface dries rapidly to form a catalyst active material coating. Spraying is stopped when the content of the catalyst active material coating reaches 5-50% of the carrier mass. The catalyst is then obtained.

6. The application of the catalyst according to any one of claims 1-4 in the preparation of allyl alcohol by isomerization of propylene oxide in a fixed-bed single-tube reactor, characterized in that: The catalyst described in any one of claims 1-4 is placed in a fixed-bed single-tube reactor, and the reactor temperature is controlled at 300-500°C under a nitrogen atmosphere and treated at this temperature for 1-5 hours; then propylene oxide is preheated at 30-80°C (preferably 30-50°C) and pumped into the fixed-bed reactor, and the reactor temperature is controlled at 250-400°C (preferably 280-320°C) and reacted at this temperature.

7. The application according to claim 6, characterized in that, The inner diameter of the fixed-bed single-tube reactor is 5mm-60mm (preferably 8mm-15mm); the height or length of the single-tube reactor is 200mm-3000mm.

8. The application according to claim 6 or 7, characterized in that, The mass hourly space velocity (MSV) of propylene oxide is 10–20 h⁻¹. -1 (Preferred time: 10-15 hours) -1 Nitrogen is used as the carrier gas, and the flow rate of nitrogen is 5-50 mL / min (preferably 5-30 mL / min).

9. The method according to claim 6, characterized in that, The product was condensed in an ice-water bath and then analyzed by gas chromatography.

Images