Propylene oxide production apparatus and production method

Abstract

The application relates to an epoxy propane preparation device and a preparation method, and belongs to the technical field of fine chemical industry. The epoxy propane preparation device comprises a tubular fluidized bed reactor, a catalyst circulation mechanism and a settling separator, the settling separator is provided with a product outlet, a separation inlet and a catalyst outlet, the outlet of the fluidized bed reactor is communicated with the separation inlet, the catalyst outlet is communicated with the inlet of the catalyst circulation mechanism, the outlet of the catalyst circulation mechanism is communicated with the inlet of the fluidized bed reactor, and the fluidized bed reactor is provided with a heat exchange mechanism along the length direction. The technical problem that the existing technology cannot effectively control and remove the reaction heat, the temperature is unstable, and the selectivity of the epoxy propane is low can be solved.

Description

Technical Field

[0001] This invention belongs to the field of fine chemical technology, and specifically relates to an apparatus and method for preparing propylene oxide. Background Technology

[0002] Propylene oxide is an important propylene derivative, mainly used in the production of polyether polyols, propylene glycol, propylene glycol ethers, isopropanolamine, propylene carbonate, etc. It is one of the main raw materials for manufacturing polyurethane, nonionic surfactants, emulsifiers, oilfield demulsifiers, flame retardants, plasticizers, lubricants, etc., and has a wide range of applications in the petroleum, chemical, pesticide, textile, and daily chemical industries.

[0003] Currently, the main methods for producing propylene oxide include the chlorohydrin process, the co-oxidation process, and the direct hydrogen peroxide oxidation process (HPPO process). The chlorohydrin process generates large amounts of waste, causing severe environmental pollution and posing significant challenges for comprehensive treatment; therefore, it has been listed as a restricted development method. The co-oxidation process, also known as the "Hacon process," includes two types: isobutane co-oxidation and ethylbenzene co-oxidation. These processes involve the co-oxidation of isobutane or ethylbenzene with propylene to produce PO, while simultaneously producing tert-butanol (TBA) or styrene (SM). The main disadvantages of this method are high investment costs, complex process flow, high requirements for raw material purity, and the generation of large amounts of byproducts during production. Its economic viability is heavily dependent on the market demand and price of these byproducts.

[0004] In recent years, green and environmentally friendly practices have become a key theme in production and daily life. The HPPO process, using propylene and industrial hydrogen peroxide as raw materials, directly oxidizes them to propylene oxide under the catalysis of titanium-silicon molecular sieve catalysts. The process is simple, the reaction conditions are mild, and the entire production process produces no harmful gas emissions. The wastewater generated can be discharged in compliance with standards after general treatment. Its advantages of being green, environmentally friendly, and having low production costs have made it one of the fastest-growing and most promising technologies currently available. The main foreign patent holders for this technology are the consortium of Evonik and ThyssenKrupp, and the consortium of BASF and Dow Chemical. Domestically developed technology is currently in a critical period of industrial application.

[0005] The key technical challenges of HPPO are addressing the issues of high reaction exotherm, limited catalyst mass transfer, factors affecting selectivity, and improving catalyst lifespan. Currently, industrialized HPPO processes all utilize an axially fixed-bed reactor, with methanol as the solvent and hydrogen peroxide oxidizing propylene to synthesize propylene oxide under the action of titanium-silicon molecular sieves. This reaction is strongly exothermic, with a unit heat of reaction of approximately 318 kJ / mol. The heat of reaction must be removed; otherwise, heat accumulation can lead to hydrogen peroxide decomposition, posing a risk of combustion and explosion, poor selectivity, and numerous byproducts. Furthermore, uneven material distribution in the axially fixed bed can cause localized "runaway" phenomena in the catalyst layer, shortening catalyst lifespan and requiring regeneration every one to two months, severely impacting the company's economic efficiency.

[0006] Chinese patent CN107417645B discloses a reactor using corrugated plates as heat transfer plates, employing four corrugated plate reactors connected in series. The circulating cooling water is forced to circulate to optimize heat removal, and the temperature of the circulating cooling water is controlled by thermometers and regulating valves to ensure uniform reaction temperature. This solves the problems of poor heat transfer and short catalyst life inherent in traditional fixed-bed reactors. However, the small gaps between the corrugated plates in the plate reactor make catalyst loading and unloading difficult.

[0007] Chinese patent CN109999727A discloses a method for synthesizing propylene oxide using a tubular fixed-bed reactor. The method includes: (1) loading a multilayer titanium-silicon molecular sieve catalyst into the tube side of the tubular fixed-bed reactor, wherein the multilayer titanium-silicon molecular sieve catalyst is loaded along the direction of increasing skeleton titanium content, and the ratio of skeleton titanium content of the (n-1)th layer titanium-silicon molecular sieve catalyst to that of the nth layer titanium-silicon molecular sieve catalyst is 1:1.5-5; (2) feeding propylene, hydrogen peroxide, methanol, and additives into the tubular fixed-bed reactor, with the feeding direction consistent with the direction of increasing activity of the multilayer titanium-silicon molecular sieve catalyst, and collecting the material from the reaction outlet after the reaction is completed. This invention exhibits uniform exothermic reaction and small temperature rise of hot spots within the tube side. However, the use of multiple types of catalysts for layered loading, with catalysts loaded in various pipes, places high demands on the catalyst loading operation and makes unloading difficult.

[0008] Chinese patent CN109180611A discloses a feeding distribution device and method for preparing propylene oxide using a direct hydrogen peroxide oxidation method with segmented raw material injection. The process employs at least two sets of reaction units connected in series, allowing the raw materials to be fed into each unit in segments. This solves the problem of uneven hydrogen peroxide distribution within the reactor, improving the conversion rate of hydrogen peroxide and the yield of propylene oxide, while reducing safety hazards. However, even with axially fixed-bed reactors, the problem of uniform material distribution remains unresolved.

[0009] Chinese patent CN104130216B discloses a process for the continuous production of propylene oxide from a propylene / propane mixture by direct oxidation with hydrogen peroxide. The reaction process employs a fluidized bed circulating reactor and a fine-particle molecular sieve catalyst. The slurry discharge passes through a flash distillation tower to separate the low-oxygen propylene / propane mixture and propylene oxide. The catalyst-containing mother liquor is separated into catalyst slurry and mother liquor by a membrane separator. After flash distillation to separate methanol from the mother liquor, the residual high-oxygen propylene / propane mixture is simultaneously recovered and recycled in a high-oxygen propylene / propane absorption tower using recovered solvent methanol. The catalyst slurry is partially regenerated online and returned to the reactor for recycling. However, this patent suffers from severe backmixing between the reaction products and reactants in the circulating reactor, resulting in low reaction efficiency and increased side reactions.

[0010] The above analysis shows that existing technologies all employ fixed-bed reactors, using enhanced heat exchange to remove the heat of reaction from the reactor. While this represents an improvement over traditional tubular reactors, it still suffers from problems such as uneven material distribution, delayed temperature control, susceptibility to localized overcooling or overheating, and low selectivity for propylene oxide. Furthermore, the operating cycle is short, requiring regeneration every 1500-2000 hours. In addition, complex reactors or reaction units also present challenges such as high equipment investment and difficulties in catalyst loading or replacement. Summary of the Invention

[0011] The purpose of this application is to provide a propylene oxide preparation apparatus that solves the technical problem that the existing technology cannot effectively control and remove the heat of reaction, resulting in unstable temperature and consequently low selectivity of propylene oxide.

[0012] This invention provides a propylene oxide preparation apparatus, including a tubular fluidized bed reactor, a catalyst circulation mechanism, and a sedimentation separator. The sedimentation separator has a product outlet, a separation inlet, and a catalyst outlet. The outlet of the fluidized bed reactor is connected to the separation inlet, the catalyst outlet is connected to the inlet of the catalyst circulation mechanism, and the outlet of the catalyst circulation mechanism is connected to the inlet of the fluidized bed reactor. The fluidized bed reactor is provided with a heat exchange mechanism along its length.

[0013] Optionally, the catalyst circulation mechanism includes a regenerator and a circulation lifter. The sedimentation separator includes a separation tank with a product outlet at the top and a separation inlet at the bottom. A teapot-spout-shaped catalyst outlet is provided on the lower side wall of the separation tank. The circulation lifter is a U-shaped tube. The outlet end of the fluidized bed reactor extends into the separation tank through the separation inlet. The catalyst outlet is connected to the inlet of the regenerator, the outlet of the regenerator is connected to the inlet of the circulation lifter, and the outlet of the circulation lifter is connected to the inlet of the fluidized bed reactor.

[0014] Optionally, the inlet of the circulating elevator is connected to a lock hopper, the inlet of the lock hopper is connected to the outlet of the regenerator, the inlet of the regenerator is connected to the catalyst outlet through a circulation pipe, and the lock hopper is provided with a catalyst addition port.

[0015] Optionally, the circulation pipe is connected to the inlet of the locked hopper via a bypass pipe.

[0016] Optionally, the circulation pipe is equipped with a flow valve.

[0017] Optionally, the inlet end of the fluidized bed reactor is configured as a Venturi distributor, and the inlet end of the Venturi distributor is provided with a microporous dispersion device, which has several micron-sized channels. The outlet of the circulating elevator is connected to the feed inlet of the Venturi distributor.

[0018] Optionally, a distributor is provided at the outlet end of the fluidized bed reactor.

[0019] This invention also provides a method for preparing propylene oxide, using any of the above-mentioned propylene oxide preparation apparatus, comprising the following steps:

[0020] Hydrogen peroxide and propylene are used as raw materials, and methanol is used as a solvent. These are then introduced into the inlet of the fluidized bed reactor.

[0021] The catalyst particles are introduced into the inlet of the fluidized bed reactor using the catalyst circulation mechanism and merged with the raw material.

[0022] The raw materials are reacted in the fluidized bed reactor under the reaction conditions;

[0023] The heat of reaction is absorbed by the heat exchange mechanism during the reaction process;

[0024] A reaction mixture containing a catalyst is obtained in the settling separator.

[0025] The reaction mixture containing the catalyst is separated using a sedimentation separator, and a reaction product containing propylene oxide is obtained at the product outlet, while a catalyst granule slurry is obtained at the catalyst outlet.

[0026] The catalyst granule slurry is recirculated using the catalyst circulation mechanism.

[0027] The reaction conditions include: a reaction flow rate of 0.06-0.5 m / s; a reaction temperature of 30-80℃; a reaction pressure of 0.6-2.5 MPa; and a hydrogen peroxide mass hourly space velocity of 0.1-10.0 hr⁻¹. -1 The molar ratio of propylene to hydrogen peroxide is (1.2-3):1; the molar ratio of methanol to hydrogen peroxide is (2.0-10):1.

[0028] Optionally, the following steps may also be included:

[0029] The catalyst particle slurry is diverted using the circulation pipe and the bypass pipe to obtain the slurry to be regenerated in the circulation pipe.

[0030] The regenerator is used to regenerate the slurry to be regenerated;

[0031] Wherein: the mass of the slurry to be regenerated is 5-30 wt% of the mass of the catalyst particle slurry.

[0032] Optionally, the catalyst particles are titanium-silicon molecular sieve HPPO catalysts, and the diameter of the catalyst particles is 0.2-1.6 mm.

[0033] One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:

[0034] An embodiment of the present invention provides a propylene oxide preparation apparatus, comprising a tubular fluidized bed reactor, a catalyst circulation mechanism, and a sedimentation separator. The sedimentation separator has a product outlet, a separation inlet, and a catalyst outlet. The outlet of the fluidized bed reactor is connected to the separation inlet, the catalyst outlet is connected to the inlet of the catalyst circulation mechanism, and the outlet of the catalyst circulation mechanism is connected to the inlet of the fluidized bed reactor. The fluidized bed reactor is provided with a heat exchange mechanism along its length. This system utilizes a fluidized bed reactor, where raw materials and catalyst are combined and flow together for reaction. Simultaneously, the raw materials and catalyst flow along the length of the reactor, avoiding the problem of localized temperature spikes at the catalyst-particle contact point caused by a fixed catalyst, which could lead to uncontrollable reaction temperatures or even "hot spots." This also avoids the low selectivity of propylene oxide, ensuring the heat of reaction is evenly distributed within the liquid flow of both raw materials and catalyst. Furthermore, a heat exchange mechanism along the length of the reactor effectively absorbs the heat of reaction. Since the liquid flow also extends along the reactor's length, it contacts and exchanges heat with the heat exchange mechanism, enhancing its heat absorption efficiency and effectively controlling and managing the reaction temperature. A sedimentation separator separates the catalyst-containing reaction mixture from the fluidized bed reactor into a concentrated slurry of propylene oxide and catalyst particles, enriching the catalyst while obtaining the product. A catalyst circulation mechanism allows the enriched catalyst to be recycled and mixed with the raw materials again, ensuring continuous catalyst flow.

[0035] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and in order to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is a schematic diagram of the propylene oxide preparation apparatus provided in an embodiment of the present invention;

[0038] Figure 2 This is a flowchart of the propylene oxide preparation method provided in the embodiments of the present invention.

[0039] Reference numerals: 10-Fluidized bed reactor; 11-Heat exchange mechanism; 12-Distributor; 13-Microporous dispersion device; 20-Regenerator; 201-Circulation pipe; 202-Bypass pipe; 203-Flow valve; 21-Sediment separator; 211-Separation tank; 2111-Product outlet; 2112-Separation inlet; 2113-Catalyst outlet; 22-Circulation elevator; 23-Closed hopper; 231-Catalyst addition port. Detailed Implementation

[0040] The present invention will be described in detail below with reference to specific embodiments and examples, thereby making the advantages and various effects of the present invention more clearly apparent. Those skilled in the art should understand that these specific embodiments and examples are for illustrative purposes only and are not intended to limit the present invention.

[0041] Throughout this specification, unless otherwise specified, the terminology used herein should be understood as having the meaning commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. In case of any conflict, this specification shall prevail. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of protection of this invention. For example, room temperature may refer to a temperature in the range of 10–35°C.

[0042] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0043] The technical solution of this application embodiment is to solve the above-mentioned technical problems, and the general idea is as follows:

[0044] Please refer to Figure 1According to a typical embodiment of the present invention, an apparatus for preparing propylene oxide is provided, comprising a tubular fluidized bed reactor 10, a catalyst circulation mechanism, and a sedimentation separator 21. The sedimentation separator 21 has a product outlet 2111, a separation inlet 2112, and a catalyst outlet 2113. The outlet of the fluidized bed reactor 10 is connected to the separation inlet 2112, the catalyst outlet 2113 is connected to the inlet of the catalyst circulation mechanism, and the outlet of the catalyst circulation mechanism is connected to the inlet of the fluidized bed reactor 10. The fluidized bed reactor 10 is provided with a heat exchange mechanism 11 along its length. By setting up a fluidized bed reactor 10, the raw materials and catalyst are combined and flowed into the fluidized bed reactor 10 for reaction. Simultaneously, the raw materials and catalyst flow together along the length of the fluidized bed reactor 10, avoiding the problem of localized temperature surges at the contact points between the raw materials and catalyst caused by a fixed catalyst, which could lead to uncontrollable reaction temperatures or even hot spots. This also avoids the problem of low selectivity for propylene oxide, ensuring that the heat of reaction generated is uniformly distributed within the liquid flow of raw materials and catalyst. At the same time, a heat exchange mechanism 11 is installed along the length of the fluidized bed reactor 10 to absorb the heat of reaction in a timely manner. Since the liquid flow also flows along the length of the fluidized bed reactor 10, it contacts and exchanges heat with the heat exchange mechanism 11, and flows relative to it, effectively improving the heat absorption effect of the heat exchange mechanism 11 and effectively controlling and handling the reaction temperature. A sedimentation separator 21 is installed to separate the catalyst-containing reaction mixture produced in the fluidized bed reactor 10 into propylene oxide and catalyst particle slurry, enriching the catalyst while obtaining the product. A catalyst circulation mechanism is installed to allow the enriched catalyst to be recycled and mixed with the raw materials again, achieving continuous catalyst flow.

[0045] It should be noted that the heat exchange mechanism 11 can be any of the prior art, preferably a cooling jacket disposed outside the fluidized bed reactor 10, or a cooling pipe or plate cooler disposed inside the fluidized bed reactor 10.

[0046] In some embodiments, the catalyst circulation mechanism includes a regenerator 20 and a circulation lifter 22. The settling separator 21 includes a separation tank 211, with a product outlet 2111 at the top and a separation inlet 2112 at the bottom. A teapot-spout-shaped catalyst outlet 2113 is provided on the lower side wall of the separation tank 211. The circulation lifter 22 is a U-shaped tube. The outlet end of the fluidized bed reactor 10 extends into the separation tank 211 through the separation inlet 2112. The catalyst outlet 2113 is connected to the inlet of the regenerator 20. The outlet of the regenerator 20 is connected to the inlet of the circulation lifter 22. The outlet of the circulation lifter 22 is connected to the inlet of the fluidized bed reactor 10. By setting up a settling separator 21 including a separation tank 211, with a product outlet 2111 at the top, a separation inlet at the bottom, and a teapot-spout-shaped catalyst outlet 2113 on the lower side wall, and allowing the outlet end of the fluidized bed reactor 10 to extend into the separation tank 211 through the separation inlet 2112 (sealed), the reaction mixture containing the catalyst from the fluidized bed reactor 10 is first allowed to accumulate in the separation tank 211. Then, liquid propylene oxide flows out from the product outlet 2111, while the concentrated slurry of catalyst particles is enriched at the bottom of the separation tank 211 under the action of gravity, and then separated and discharged through the catalyst outlet 2113. Since the outlet end of the fluidized bed reactor 10 extends into the separation tank 211 through the separation inlet 2112 (sealed), the backmixing of propylene oxide product or catalyst slurry can be effectively avoided. By setting up a catalyst circulation mechanism including a regenerator 20 and a circulation booster 22, the regenerator 20 is used to regenerate the catalyst particle slurry, maintaining the activity and selectivity of the catalyst. The circulation booster 22 is set up as a U-shaped pipe and a booster pipeline (not shown in the figure), which is used to realize catalyst circulation and flow control.

[0047] In some embodiments, the inlet of the circulating elevator 22 is connected to a closed hopper 23, the inlet of the closed hopper 23 is connected to the outlet of the regenerator 20, and the inlet of the regenerator 20 is connected to the catalyst outlet 2113 through a circulation pipe 201. The closed hopper 23 is provided with a catalyst addition port 231. By setting the closed hopper 23, the catalyst is collected while the catalyst flow rate is controlled. The catalyst addition port 231 is provided on it for replenishing the catalyst at any time. At the same time, it is also provided with a catalyst removal port for replacing the deactivated catalyst inside.

[0048] In some embodiments, the circulation pipe 201 is connected to the inlet of the closed hopper 23 via a bypass pipe 202. By setting up the circulation pipe 201 and the bypass pipe 202, the catalyst particle slurry is diverted, allowing only a portion of the catalyst particle slurry to flow into the regenerator 20 for regeneration. Since the catalyst is only partially deactivated after a few reactions, only a portion of the catalyst needs to be regenerated periodically, thereby effectively avoiding overloading the regenerator 20 by feeding all the catalyst into it.

[0049] In some embodiments, the circulation pipe 201 is equipped with a flow valve 203. By setting the flow valve 203, the proportion of catalyst particle slurry obtained by the circulation pipe 201 can be effectively controlled, thereby allowing for precise and effective regulation according to actual conditions.

[0050] In some embodiments, the inlet end of the fluidized bed reactor 10 is configured as a Venturi distributor, and the inlet end of the Venturi distributor is provided with a microporous dispersion device 13. The microporous dispersion device 13 has several micron-sized channels, and the outlet of the circulating elevator 22 is connected to the feed inlet of the Venturi distributor. By configuring the inlet end of the fluidized bed reactor 10 as a Venturi distributor, the raw material can be sprayed into the fluidized bed reactor 10. By configuring the microporous dispersion device 13, the raw material is effectively dispersed to form microdroplets, which greatly increases the mass transfer area, effectively premixes, increases the residence time, reduces the reaction pressure, and reduces energy consumption.

[0051] In some embodiments, a distributor 12 is provided at the outlet end of the fluidized bed reactor 10. The distributor 12 is used to ensure that the fluidized bed reactor 10 has a plug flow, that the catalyst and raw materials are a uniformly mixed slurry without backmixing, and that the reaction products are easily separated from the catalyst.

[0052] According to another typical embodiment of the present invention, a method for preparing propylene oxide is also provided, which employs any of the above-mentioned propylene oxide preparation apparatus and includes the following steps:

[0053] S1. Hydrogen peroxide and propylene are used as raw materials, and methanol is used as a solvent. These are introduced into the inlet of the fluidized bed reactor 10.

[0054] S2. The catalyst particles are introduced into the inlet of the fluidized bed reactor 10 using the catalyst circulation mechanism and merged with the raw material.

[0055] S3. The raw materials are reacted in the fluidized bed reactor 10 under the reaction conditions.

[0056] S4. During the reaction process, the heat of reaction is absorbed through the heat exchange mechanism 11.

[0057] S5. A reaction mixture containing the catalyst is obtained in the sedimentation separator 21.

[0058] S6. The reaction mixture containing the catalyst is separated by the sedimentation separator 21, and the reaction product containing propylene oxide is obtained at the product outlet 2111, and the catalyst particle slurry is obtained at the catalyst outlet 2113.

[0059] S7. The catalyst particle slurry is recirculated using the catalyst circulation mechanism.

[0060] The concentration of hydrogen peroxide is 27.5-70 wt%; the reaction conditions include: a reaction flow rate of 0.06-0.5 m / s; a reaction temperature of 30-80℃; a reaction pressure of 0.6-2.5 MPa; and a mass hourly space velocity (HSV) of 0.1-10.0 hr. -1 The molar ratio of propylene to hydrogen peroxide is (1.2-3):1; the molar ratio of methanol to hydrogen peroxide is (2.0-10):1.

[0061] Preferably, the reaction flow rate is 0.1-0.3 m / s; the reaction temperature is 35-50℃; the reaction pressure is 1.6-2.0 MPa; and the mass hourly space velocity (HSV) of hydrogen peroxide is 1.0-5.0 hr. -1 The molar ratio of propylene to hydrogen peroxide is (1.2-1.5):1; the molar ratio of methanol to hydrogen peroxide is (4-6):1.

[0062] In some embodiments, the following steps are also included:

[0063] S6.1 The catalyst particle slurry is diverted using the circulation pipe 201 and the bypass pipe 202, and the slurry to be regenerated is obtained in the circulation pipe 201.

[0064] S6.2 The slurry to be regenerated is regenerated using the regenerator 20.

[0065] Wherein: the mass of the slurry to be regenerated is 5-30 wt% of the mass of the catalyst particle slurry, preferably 10-20 wt%.

[0066] In some embodiments, the catalyst particles are titanium-silicon molecular sieve HPPO catalysts, and the diameter of the catalyst particles is 0.2-1.6 mm, preferably 0.5-1.0 mm.

[0067] The solution of this application will be described in detail below with reference to embodiments, comparative examples and experimental data.

[0068] Example 1

[0069] This embodiment provides a method for preparing propylene oxide, including the following steps:

[0070] S1. Hydrogen peroxide and propylene are used as raw materials, and methanol is used as a solvent. These are introduced into the inlet of the fluidized bed reactor 10.

[0071] S2. The catalyst particles are introduced into the inlet of the fluidized bed reactor 10 using the catalyst circulation mechanism and merged with the raw material.

[0072] S3. The raw materials are reacted in the fluidized bed reactor 10 under the reaction conditions.

[0073] S4. During the reaction process, the heat of reaction is absorbed through the heat exchange mechanism 11.

[0074] S5. A reaction mixture containing the catalyst is obtained in the sedimentation separator 21.

[0075] S6. The reaction mixture containing the catalyst is separated by the sedimentation separator 21, and the reaction product containing propylene oxide is obtained at the product outlet 2111, and the catalyst particle slurry is obtained at the catalyst outlet 2113.

[0076] S6.1 The catalyst particle slurry is diverted using the circulation pipe 201 and the bypass pipe 202, and the slurry to be regenerated is obtained in the circulation pipe 201.

[0077] S6.2 The slurry to be regenerated is regenerated using the regenerator 20.

[0078] S7. The catalyst particle slurry is recirculated using the catalyst circulation mechanism.

[0079] The fluidized bed reactor 10 has a diameter of 50 mm and a height (length) of 12 m; the hydrogen peroxide concentration is 50 wt%, and the propylene volume content is 99%; the catalyst particles are TS-1 type titanium-silicon molecular sieve HPPO catalyst. The reaction conditions include: a reaction flow rate of 0.1 m / s; a reaction temperature of 35℃; a reaction pressure of 2.0 MPa; a molar ratio of hydrogen peroxide, propylene, and methanol of 1:1.5:4; and a catalyst circulation rate of 15 kg / h.

[0080] Example 2

[0081] This embodiment provides a method for preparing propylene oxide, which differs from Example 1 only in that the reaction flow rate is 0.25 m / s.

[0082] Example 3

[0083] This embodiment provides a method for preparing propylene oxide, which differs from Example 1 only in that the molar ratio of hydrogen peroxide, propylene, and methanol is 1:1.5:2.

[0084] Example 4

[0085] This embodiment provides a method for preparing propylene oxide, which differs from Example 1 only in that the concentration of hydrogen peroxide is 27.5 wt%.

[0086] Example 5

[0087] This embodiment provides a method for preparing propylene oxide, which differs from Example 4 only in that the catalyst circulation rate is 20 kg / h.

[0088] Comparative Example 1

[0089] Chinese patent CN109999727A describes the synthesis of propylene oxide using a tubular fixed-bed reactor. The reactor's tubes are filled with a multilayer titanium-silicon molecular sieve catalyst, and propylene, hydrogen peroxide, methanol, and additives are fed into the reactor. Comparing Examples 1-4 disclosed in this patent, the optimal result was selected as Comparative Example 1.

[0090] Comparative Example 2

[0091] Chinese patent CN109180611A uses a two-stage tubular fixed-bed reactor. The implementation effect disclosed in this patent is selected as comparative example 2.

[0092] Comparative Example 3

[0093] Chinese patent CN104130216B discloses a process for the continuous production of propylene oxide by direct oxidation of a propylene / propane mixture with hydrogen peroxide. The reaction process uses a fluidized bed circulating reactor. The best implementation effect disclosed in this patent is selected as comparative example 3.

[0094] Experimental Example 1

[0095] Propylene oxide was prepared according to the methods described in Examples 1-5 and Comparative Examples 1-3. After the reaction was completed, the conversion rate of hydrogen peroxide and the selectivity of propylene oxide were calculated, and the results are shown in Table 1.

[0096] Table 1

[0097]

[0098] As shown in Table 1, based on the comparison between Examples 1-5 and Comparative Examples 1-3, the hydrogen peroxide conversion rate of the propylene oxide preparation apparatus and preparation method provided by the present invention is much higher than that of the prior art, with a hydrogen peroxide conversion rate ≥99.6%. Furthermore, it can effectively control the reaction temperature rise ≤3℃, enabling continuous production and operation, and can effectively ensure the selectivity of propylene oxide, with a selectivity ≥99.7%.

[0099] One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:

[0100] (1) The propylene oxide preparation device provided in the embodiments of the present invention realizes the continuous and stable operation of propylene epoxidation reaction and deactivated catalyst regeneration, effectively maintains the equilibrium activity of the catalyst, improves the selectivity of the target product, and greatly improves the operation cycle and economy of the device.

[0101] (2) The propylene oxide preparation device provided in the embodiments of the present invention adopts a fluidized bed reactor, the reaction material flows horizontally, the reaction temperature is uniform, there are no hot spots, the side reaction is greatly suppressed, the reaction conversion rate and product selectivity are high, and the catalyst has a long service life.

[0102] (3) The propylene oxide preparation device provided in the embodiments of the present invention disperses hydrogen peroxide into microdroplets by setting a microporous dispersion device. The micro-interface mass transfer area is large, the reaction residence time is long, and the contact time between the reactants and the catalyst is short, which effectively suppresses the occurrence of side reactions.

[0103] (4) The propylene oxide preparation device provided in the embodiments of the present invention, by setting up circulation pipe and bypass pipe, splits the catalyst so that the catalyst is only partially regenerated, the consumption of regeneration medium is small, it can be recycled, and the device has low energy consumption.

[0104] (5) The propylene oxide preparation apparatus provided in the embodiments of the present invention, by setting the circulation booster to a U-shaped tube, allows for flexible control of catalyst circulation and reduces catalyst wear.

[0105] (6) The propylene oxide preparation apparatus provided in this embodiment of the invention, by setting a closed hopper, adjusting the pressure between the regenerator and the fluidized bed reactor, guides the catalyst circulation and delivery, and the catalyst system operates stably and controllably.

[0106] (7) The present invention provides a method for preparing propylene oxide. Using this method, the hydrogen peroxide conversion rate is ≥99.6%, and the reaction temperature rise can be effectively controlled to ≤3℃. It can be continuously produced and operated, and the selectivity of propylene oxide can be effectively guaranteed to be ≥99.7%.

[0107] Finally, it should be noted that the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0108] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0109] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A propylene oxide preparation apparatus, characterized in that, It includes a tubular fluidized bed reactor (10), a catalyst circulation mechanism and a settling separator (21), the settling separator (21) having a product outlet (2111), a separation inlet (2112) and a catalyst outlet (2113). The outlet of the fluidized bed reactor (10) is connected to the separation inlet (2112). The catalyst outlet (2113) is connected to the inlet of the catalyst circulation mechanism. The outlet of the catalyst circulation mechanism is connected to the inlet of the fluidized bed reactor (10). The fluidized bed reactor (10) is provided with a heat exchange mechanism (11) along its length to absorb the heat of reaction in real time and control the temperature rise to ≤3℃; the heat exchange mechanism (11) is a cooling pipe or plate cooler installed inside the fluidized bed reactor (10); The catalyst circulation mechanism is used to regenerate and circulate a portion of the catalyst particles, including a regenerator (20) and a circulation booster (22). The sedimentation separator (21) includes a separation tank (211), a product outlet (2111) at the top of the separation tank (211), a separation inlet (2112) at the bottom of the separation tank (211), a teapot spout-shaped catalyst outlet (2113) on the lower side wall of the separation tank (211), and the circulation lifter (22) is a U-shaped pipe; The outlet end of the fluidized bed reactor (10) extends into the separation tank (211) through the separation inlet (2112). The catalyst outlet (2113) is connected to the inlet of the regenerator (20). The outlet of the regenerator (20) is connected to the inlet of the circulation lifter (22). The outlet of the circulation lifter (22) is connected to the inlet of the fluidized bed reactor (10). The inlet end of the fluidized bed reactor (10) is configured as a Venturi distributor, and the inlet end of the Venturi distributor is provided with a microporous dispersion device (13). The microporous dispersion device (13) has several micron-sized channels. The outlet of the circulating elevator (22) is connected to the feed inlet of the Venturi distributor.

2. The propylene oxide preparation apparatus according to claim 1, characterized in that, The inlet of the circulating elevator (22) is connected to the lock hopper (23), the inlet of the lock hopper (23) is connected to the outlet of the regenerator (20), the inlet of the regenerator (20) is connected to the catalyst outlet (2113) through the circulation pipe (201), and the lock hopper (23) is provided with a catalyst addition port (231).

3. The propylene oxide preparation apparatus according to claim 2, characterized in that, The circulation pipe (201) is connected to the inlet of the locked hopper (23) through the bypass pipe (202).

4. The propylene oxide preparation apparatus according to claim 3, characterized in that, The circulation pipe (201) is equipped with a flow valve (203).

5. The propylene oxide preparation apparatus according to claim 4, characterized in that, The fluidized bed reactor (10) is equipped with a distributor (12) at its outlet end.

6. A method for preparing propylene oxide, characterized in that, The preparation is carried out using the propylene oxide preparation apparatus according to any one of claims 3-5, comprising the following steps: Hydrogen peroxide and propylene are used as raw materials, and methanol is used as a solvent. These materials are introduced into the inlet of the fluidized bed reactor (10). The catalyst particles are fed into the inlet of the fluidized bed reactor (10) using the catalyst circulation mechanism and merged with the raw material; The raw materials are reacted in the fluidized bed reactor (10) under the reaction conditions; The heat of reaction is absorbed through the heat exchange mechanism (11) during the reaction process; A reaction mixture containing a catalyst is obtained in the settling separator (21); The reaction mixture containing the catalyst is separated by a settling separator (21), and a reaction product containing propylene oxide is obtained at the product outlet (2111), and a catalyst particle slurry is obtained at the catalyst outlet (2113). The catalyst granule slurry is recirculated using the catalyst circulation mechanism. The catalyst particle slurry is diverted using the circulation pipe (201) and the bypass pipe (202) to obtain the slurry to be regenerated in the circulation pipe; The slurry to be regenerated is regenerated using the regenerator (20); wherein the mass of the slurry to be regenerated is 5-30 wt% of the mass of the catalyst particle slurry. The reaction conditions include: The reaction flow rate is 0.06-0.5 m / s; The reaction temperature is 30-80℃; The reaction pressure is 0.6-2.5 MPa; The mass hourly space velocity (MSV) of hydrogen peroxide is 0.1-10.0 hr. -1 ; The molar ratio of propylene to hydrogen peroxide is (1.2-3):1; The molar ratio of methanol to hydrogen peroxide is (2.0-10):

1.

7. The method for preparing propylene oxide according to claim 6, characterized in that, The catalyst particles are titanium-silicon molecular sieve HPPO catalysts, and the diameter of the catalyst particles is 0.2-1.6 mm.

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