Device for producing epoxypropane by hydrogen peroxide direct oxidation method

Abstract

The utility model relates to the technical field of chemical synthesis, and provides a device for producing epoxypropane by a hydrogen peroxide direct oxidation method, which comprises a single reaction unit or N reaction units connected in series, and N is at least 2; when the device is a single reaction unit, the reactor is connected with a solvent input pipe, a hydrogen peroxide input pipe and a propylene input pipe, and a discharge port of the reactor is connected with a feed port of the liquid-liquid phase splitting device; a propylene-rich phase outlet of the liquid-liquid phase separation device is connected with a feeding hole of the reactor, and a solvent-rich phase outlet of the liquid-liquid phase separation device is connected with a subsequent separation unit; when the device comprises N reaction units which are connected in series, the rich solvent phase outlet of the liquid-liquid phase separation device in the previous reaction unit is connected with the feed port of the reactor in the next reaction unit, and the rich solvent phase outlet of the liquid-liquid phase separation device in the last reaction unit is connected with the subsequent separation unit. The device reduces the circulation volume of propylene and a solvent in a separation process, is high in raw material conversion rate and yield, safe and stable in operation, energy-saving and consumption-reducing.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of chemical synthesis technology, concretely relates to a device for producing propylene oxide by hydrogen peroxide direct oxidation method. BACKGROUND

[0002] Propylene oxide (PO) is an important basic organic chemical raw material, the third largest propylene derivative besides polypropylene and acrylonitrile, mainly used for producing polyether polyols, propylene glycol and propylene glycol ether and other chemical products, widely applied in thermal insulation materials, building materials, automobiles, food, medicine, cosmetics, paint and adhesive fields. These applications not only reflect the diversity and importance of propylene oxide, but also provide a solid foundation for its market demand.

[0003] In recent years, propylene oxide preparation process has developed rapidly, among them, hydrogen peroxide direct oxidation method for preparing propylene oxide (HPPO) has the advantages of simple process, small environmental impact, mild reaction conditions, high raw material utilization efficiency, and is gradually replacing the traditional production process of propylene oxide.

[0004] HPPO process is a direct oxidation reaction of propylene and hydrogen peroxide in a circulating solvent under relatively mild conditions, and titanium-silicon molecular sieve (TS-1) catalysis in a reactor to prepare propylene oxide. A large number of researches have been carried out on HPPO process at home and abroad, such as patent US2003009040A1 discloses an olefin epoxidation process, which uses a heterogeneous mixed system composed of one liquid phase rich in hydrogen peroxide and solvent and one organic liquid phase rich in propylene, which can significantly improve the selectivity of propylene oxide without affecting the conversion rate of hydrogen peroxide, but the patent does not involve the subsequent separation process of the two-phase system. Patent CN103641800A discloses a production method of propylene oxide, which relates to a method for producing propylene oxide by connecting three reactors in series, the load of a single reactor is distributed to the first two reactors, the excess propylene and methanol in the first reactor are recycled in the second reactor by maintaining the molar ratio of methanol / propylene / hydrogen peroxide input by a single reactor, which reduces the circulation amount of propylene and methanol, but the final reaction stream still needs to be separated from the solvent and propylene by using high energy consumption methods such as rectification and then recycled back to the reactor. Patent CN101693703A discloses an energy-saving and emission-reducing process for producing propylene oxide by hydrogen peroxide epoxidation of propylene, propylene and hydrogen peroxide are subjected to epoxidation reaction under medium pressure and low temperature by titanium-silicon molecular sieve, and the reaction product is separated from unreacted propylene in a propylene rectification tower, and the circulating solvent is separated from the top of the solvent rectification tower; although the propylene tower bottom stream is used as part of the heat source of the subsequent rectification tower, part of the energy is recovered, but a large amount of fresh steam is still consumed in the separation process.

[0005] It is worth noting that in the actual process, in order to improve the conversion rate of hydrogen peroxide and the yield of propylene oxide, reduce the safety hidden danger of combustion and explosion and inhibit the occurrence of side reactions, in addition to using a highly selective catalyst, an excess of propylene and a large amount of circulating solvent should be provided; and in the subsequent reaction product separation process, the excess propylene and the solvent need to be separated and purified respectively and then returned to the epoxidation reactor for recycling, which is mainly carried out by distillation, which needs to consume a large amount of energy, seriously affecting the economy of the process. Practical new type content

[0006] In view of the deficiencies in the prior art, the utility model discloses a kind of hydrogen peroxide direct oxidation method production propylene oxide devices, the hydrogen peroxide conversion rate and propylene oxide yield of the device are high, so that propylene and solvent circulation amount are lower in subsequent separation process, and energy saving and consumption reduction are run safely and stably, suitable for large-scale popularization and application.

[0007] In order to achieve the above technical purpose, on the one hand, the utility model provides a kind of hydrogen peroxide direct oxidation method production propylene oxide device, the device is single reaction unit or includes N series of reaction units, N is at least 2;

[0008] The reaction unit includes a reactor and a liquid-liquid phase separation device, the reactor is used for propylene and hydrogen peroxide to react to obtain propylene oxide under the action of catalyst, and the liquid-liquid phase separation device is used for liquid-liquid phase separation of the material after the reactor reaction to obtain propylene-rich phase and solvent-rich phase;

[0009] When the device is a single reaction unit, the reactor is connected with a solvent input pipe, a hydrogen peroxide input pipe and a propylene input pipe, and the discharge port of the reactor is connected with the feed port of the liquid-liquid phase separation device; the propylene-rich phase outlet of the liquid-liquid phase separation device is connected with the feed port of the reactor, and the solvent-rich phase outlet of the liquid-liquid phase separation device is connected with a subsequent separation unit.

[0010] When the device includes N series of reaction units, the feed port of the reactor in the first reaction unit is connected with a solvent input pipe, the feed port of the reactor in any reaction unit is connected with a hydrogen peroxide input pipe and a propylene input pipe, and the discharge port is connected with the feed port of the liquid-liquid phase separation device; the propylene-rich outlet of the liquid-liquid phase separation device in any reaction unit is connected with the feed port of the reactor in the same reaction unit, the solvent-rich outlet of the liquid-liquid phase separation device in the previous reaction unit is connected with the feed port of the reactor in the next reaction unit, and the solvent-rich outlet of the liquid-liquid phase separation device in the last reaction unit is connected with a subsequent separation unit.

[0011] In the process of producing propylene oxide by direct oxidation of hydrogen peroxide using the above device, when the reaction is carried out in a single reaction unit, the solvent, propylene and hydrogen peroxide are input into the reactor for reaction, and after the reaction is completed, the material is separated by the liquid-liquid phase separation device to obtain a propylene-rich phase which is returned to the reactor, and a solvent-rich phase which is input into the subsequent separation process; when the reaction is carried out in N reaction units in series, the solvent is input into the reactor of the first reaction unit, and the propylene and hydrogen peroxide are input into the reactors of each reaction unit; the propylene-rich phase obtained by the liquid-liquid phase separation device of any reaction unit is returned to the reactor in the same reaction unit, the solvent-rich phase obtained by the liquid-liquid phase separation device of the previous reaction unit is input into the reactor of the next reaction unit for reaction, and the solvent-rich phase obtained by the liquid-liquid phase separation device of the last reaction unit is input into the subsequent separation process.

[0012] In the above technical solution, in any single reaction unit, the solvent, raw material propylene and hydrogen peroxide (aqueous solution of hydrogen peroxide) are input into the reactor, and the following reaction occurs in the reactor under the action of the catalyst:

[0013] CH3CH=CH2+H2O2→CH3CH(O)CH2+H2O

[0014] The reacted material is input into the liquid-liquid phase separation device for phase separation to obtain a propylene-rich phase and a solvent-rich phase, wherein the propylene-rich phase comprises propylene, solvent and propylene oxide, and the mass fraction of propylene is the highest; the solvent-rich phase comprises methanol, water, propylene and propylene oxide, and the mass fraction of the solvent is the highest. When the epoxidation reaction is carried out in a single reaction unit, the propylene-rich phase obtained by phase separation is returned to the reactor for continuous reaction, thereby effectively reducing the circulation amount of propylene and solvent in the subsequent separation process, thereby reducing the energy consumption of the separation process. In addition, the solvent-rich phase is input into the subsequent separation process to separate the product, solvent, propylene and remove water, and the phase separation operation causes the enrichment of propylene oxide in the solvent-rich phase, thereby further reducing the operation difficulty and energy saving of the subsequent separation process. When the epoxidation reaction is carried out in N reaction units, the propylene-rich phase obtained after phase separation in each reaction section is returned, thereby reducing the proportion of propylene and solvent in the solvent-rich phase output from the liquid-liquid phase separation device of the last reaction unit, thereby reducing the load of the subsequent separation unit and reducing energy consumption. In addition, through the series connection of multiple reaction units, the excess solvent and propylene in the previous group of reaction units are input into the next group of reaction units in the form of a solvent-rich phase, thereby reducing the input amount of fresh propylene and solvent in the next group of reaction units, thereby reducing the propylene and solvent flow into the subsequent separation process as a whole, and further reducing the energy consumption and separation difficulty of the subsequent separation process.

[0015] The embodiments and comparative examples of the utility model show the process of producing propylene oxide by direct oxidation of hydrogen peroxide.

[0016] Compared with the prior art, the hydrogen peroxide direct oxidation method production propylene oxide device has the beneficial effects that:

[0017] The hydrogen peroxide direct oxidation method production propylene oxide device has the beneficial effects that: BRIEF DESCRIPTION OF DRAWINGS

[0018] The drawings accompanying the specification of this application form a part thereof, serve to provide further understanding of the present application, and together with the description provide a basis for the practice of the present application. The illustrative embodiments of the present application described herein are not meant to be limiting and do not exhaust the scope of the present application. In the drawings:

[0019] Figure 1 Fig. 1 shows a structural diagram of the hydrogen peroxide direct oxidation method production propylene oxide device of the present application;

[0020] Figure 2 Fig. 2 shows another structural diagram of the hydrogen peroxide direct oxidation method production propylene oxide device of the present application;

[0021] Figure 3 Fig. 3 shows another structural diagram of the hydrogen peroxide direct oxidation method production propylene oxide device of the present application;

[0022] Figure 4 Fig. 4 shows another structural diagram of the hydrogen peroxide direct oxidation method production propylene oxide device of the present application.

[0023] In the above drawings, the following reference signs are used:

[0024] 1-reactor, 11-first reactor, 12-second reactor, 2-liquid-liquid phase separation device, 21-first liquid-liquid phase separation device, 22-second liquid-liquid phase separation device, 3-cooler, 31-first cooler, 32-second cooler. DETAILED DESCRIPTION

[0025] For the convenience of understanding the utility model, the utility model will be described more fully below, and a preferred embodiment of the utility model is given. It should be understood that these embodiments are only used for more detailed description, and should not be understood as limiting the utility model in any form, that is, it is not intended to limit the protection scope of the utility model.

[0026] Unless otherwise defined, the technical terms used in the following examples have the same meaning as generally understood by those skilled in the art to which the utility model belongs. The test reagents used in the following examples are conventional biochemical reagents unless otherwise specified, and the experimental methods are conventional methods unless otherwise specified.

[0027] Example 1

[0028] A device for producing propylene oxide by hydrogen peroxide direct oxidation method, as shown in the figure, the device comprises a single reaction unit, the reaction unit comprises a reactor 1 and a liquid-liquid phase separation device 2, the reactor 1 is used for propylene and hydrogen peroxide to react under the action of catalyst to obtain propylene oxide, and the liquid-liquid phase separation device 2 is used for liquid-liquid phase separation of the material after the reactor 1 reaction, to obtain a propylene-rich phase containing propylene and solvent, and a solvent-rich phase containing solvent and water. Figure 1

[0029] The feed inlet of the reactor 1 is connected with a solvent input pipe, a hydrogen peroxide input pipe and a propylene input pipe, and the discharge outlet of the reactor 1 is connected with the feed inlet of the liquid-liquid phase separation device 2; the propylene-rich phase outlet of the liquid-liquid phase separation device 2 is connected with the feed inlet of the reactor 1, and the solvent-rich phase outlet of the liquid-liquid phase separation device 2 is connected with a subsequent separation unit.

[0030] Further, the reactor 1 of any one reaction unit is independently selected from a shell-and-tube reactor, a tank reactor or a column reactor, and in the actual process, a suitable reactor 1 type can be selected according to the need.

[0031] The utility model is not limited to the position of the reactant material input into the reactor 1, and in a further example of the utility model, the reactor 1 is fed from the top, the bottom or the side, and a suitable feeding position can be selected according to the need in the specific process.

[0032] Further, a liquid distribution device is arranged in any one of the reaction units, which is used for uniformly distributing the material input into the reactor 1, so as to promote the uniform mixing and sufficient contact of the reactants. It should be noted that the specific structure of the liquid distribution device is not limited in the utility model, and a device or arrangement that can promote the distribution of two-phase or multi-phase liquid can be selected by those skilled in the art, and the protection scope of the utility model is not limited thereby.

[0033] ​Further, in any of the reaction units, a cooler 3 and / or a filtering device are arranged on the pipeline connecting the discharge port of the reactor 1 and the feed port of the liquid-liquid phase separation device 2, so that in a specific working condition, the material output by the reactor 1 can be temperature-adjusted by the cooler 3 to improve the efficiency of the subsequent phase separation operation, or the entrained catalyst particles can be separated by the filtering device to protect the stability of the downstream arrangement and operation. Figure 2 The utility model discloses a hydrogen peroxide direct oxidation method production epoxypropane's device of one structure of the device of the utility model shows containing cooler.

[0034] Further, the reactor 1 and the liquid-liquid phase separation device 2 in the same reaction unit are integrated equipment or separate equipment, and in the actual process, the reactor 1 and the liquid-liquid phase separation device 2 can be arranged separately or operated in the form of integrated equipment according to the needs, which can meet the needs of more working conditions.

[0035] Further, the liquid-liquid phase separation device 2 can be a static phase separation device or a dynamic separation device, and a person skilled in the art can select according to the needs, and in the optional example of the utility model, the liquid-liquid phase separation device 2 is preferably a static phase separation device.

[0036] Example 2

[0037] A hydrogen peroxide direct oxidation method for producing epoxypropane, the method of the embodiment is operated by the device shown in the figure, and the production scale of epoxypropane is 150,000 tons. Figure 2

[0038] Specifically, the molar ratio of methanol, propylene and hydrogen peroxide in the reactor 1 is 6.2:3:1, wherein the methanol feed flow is 69.2t / h, the 50% hydrogen peroxide aqueous solution feed flow is 24.6t / h, the propylene feed flow is 31.5t / h, and the propylene-rich phase flow returned from the liquid-liquid phase separation device 2 is 20.2t / h. The reactor 1 is a tubular fixed bed reactor, which is provided with a liquid distribution device for uniformly distributing the feed material, and then the reactor 1 is used for the epoxidation reaction under the catalysis of titanium-silicon molecular sieve TS-1 (the titanium-silicon ratio is SiO2:TiO2=25) at 45 DEG C and 2.4MPaG; the mass space velocity of the catalyst is 0.05-1.2h -1 .

[0039] ​The effluent from reactor 1 is cooled to 35°C by the discharge cooler 3 and then enters the liquid-liquid phase separation unit 2 for phase separation. The flow rate of the propylene-rich phase obtained by separation is 20.2 t / h, including propylene, methanol, and propylene oxide with mass contents of approximately 70.2%, 13.9%, and 15.9%, respectively. This part of the material is returned to the inlet of reactor 1. The flow rate of the solvent-rich phase is 125.2 t / h, including methanol, water, propylene, and propylene oxide with mass contents of 55.1%, 14.7%, 13.8%, and 15.3%, respectively, as well as some other impurities. This part of the material enters the subsequent separation unit to separate methanol, propylene, and propylene oxide products.

[0040] After subsequent separation, the final propylene oxide product in this embodiment is 18.75 t / h. The purified methanol and propylene are recycled back to the reaction unit for further reaction, with circulation flow rates of 68.9 t / h and 17.3 t / h, respectively (excluding separation losses). The subsequent separation units in this embodiment include a methanol double-effect separator and a propylene separator. The 2.5 MPaG steam consumption of the methanol double-effect separator is 59.7 t / h, and the 0.5 MPaG steam consumption of the propylene separator is 4.93 t / h.

[0041] Comparative Example 1

[0042] This comparative example illustrates a process for the direct oxidation of propylene with hydrogen peroxide to produce propylene oxide, with a propylene oxide production scale of 150,000 tons. Specifically:

[0043] The molar ratio of methanol:propylene:hydrogen peroxide in the reactor was 6.2:3:1, with a methanol feed rate of 72.0 t / h, a 50% hydrogen peroxide aqueous solution feed rate of 24.6 t / h, and a propylene feed rate of 45.7 t / h. The reactor was a tubular fixed-bed reactor equipped with a liquid distribution device for mixing the feed materials. The epoxidation reaction was carried out in the reactor under the catalytic action of titanium-silicon molecular sieve TS-1 (titanium-silicon ratio SiO2:TiO2 = 25) at 45°C and 2.4 MPaG. The mass hourly space velocity (MHSV) of the catalyst was the same as that of the catalyst in Example 2.

[0044] The reactor outlet stream is cooled to 35°C by the discharge cooler 3 and then enters the liquid-liquid phase separator 2 for phase separation. The flow rate of the propylene-rich phase is 19.8 t / h, with propylene, methanol, and propylene oxide mass contents of 71.8%, 14.3%, and 13.9%, respectively. The flow rate of the solvent-rich phase is 122.4 t / h, with methanol, water, propylene, and propylene oxide mass contents of 56.4%, 14.9%, 14.2%, and 13.3%, respectively, along with some other impurities. Both the propylene-rich and solvent-rich phase streams enter subsequent separation units to separate methanol, propylene, and propylene oxide products.

[0045] In this comparative example, the final product of propylene oxide was 18.75 t / h. The purified methanol and propylene were recycled back to the reaction unit at flow rates of 71.7 t / h and 31.5 t / h, respectively (ignoring separation losses). Subsequent separation units included a methanol double-effect separator and a propylene separator. The methanol double-effect separator consumed 61.7 t / h of 2.5 MPaG steam, and the propylene separator consumed 8.98 t / h of 0.5 MPaG steam.

[0046] Combining Example 2 and Comparative Example 1, it can be verified that to achieve the same propylene oxide yield, the process in Comparative Example 1 requires increased input of propylene and solvent methanol. Furthermore, after the reaction, the propylene and solvent streams input to the subsequent separation unit in Comparative Example 1 are larger than those in Example 1. It can be inferred that the subsequent separation process in Comparative Example 1 will generate higher energy consumption. By comparing and analyzing the distillation column energy consumption of the subsequent separation processes in Example 1 and Comparative Example 1, it is confirmed that the direct hydrogen peroxide oxidation method for producing propylene oxide in Example 1 can significantly reduce process energy consumption and ensure stable and safe operation.

[0047] Example 3

[0048] Based on the apparatus for producing propylene oxide by direct oxidation of hydrogen peroxide shown in Example 1, this embodiment proposes another apparatus for producing propylene oxide by direct oxidation of hydrogen peroxide. The difference between the apparatus in this embodiment and the apparatus shown in Example 1 is that this embodiment includes N reaction units connected in series, where N is at least 2.

[0049] In this system, the feed inlet of reactor 1 in the first reaction unit is connected to the solvent input pipe; the feed inlet of reactor 1 in any reaction unit is connected to the hydrogen peroxide input pipe and the propylene input pipe, and the discharge outlet is connected to the feed inlet of liquid-liquid phase separator 2; the propylene-rich outlet of liquid-liquid phase separator 2 in any reaction unit is connected to the feed inlet of reactor 1 in the same reaction unit; the solvent-rich phase outlet of liquid-liquid phase separator 2 in the previous reaction unit is connected to the feed inlet of reactor 1 in the next reaction unit; and the solvent-rich phase outlet of liquid-liquid phase separator 2 in the last reaction unit is connected to the subsequent separation unit.

[0050] Figure 3The figure illustrates an example of an apparatus for producing propylene oxide via direct hydrogen peroxide oxidation, comprising two reaction units. As shown, the raw materials hydrogen peroxide and propylene, along with a solvent, are fed into the first reactor 11 of the first reaction unit for an epoxidation reaction. The resulting material is fed into a first liquid-liquid phase separator 21 for phase separation. The propylene-rich phase obtained from the phase separation is returned to the inlet of the first reactor 11, while the solvent-rich phase obtained is fed into the second reactor 12 of the second reaction unit. Newly fed hydrogen peroxide and propylene undergo an epoxidation reaction in the second reactor 12. The resulting material is fed into the second liquid-liquid phase separator 21 for phase separation. The propylene-rich phase obtained from the phase separation is returned to the inlet of the second reactor 12, while the solvent-rich phase obtained is fed into a subsequent separation unit.

[0051] Figure 4 An apparatus for producing propylene oxide by direct hydrogen peroxide oxidation, comprising a first cooler 31 and a second cooler 32, is shown. Specifically, the reaction product output from the first reactor 11 is cooled by the first cooler 31 and then fed into the first liquid-liquid phase separation device 21, and the reaction product output from the second reactor 12 is cooled by the second cooler 32 and then fed into the second liquid-liquid phase separation device 21.

[0052] It should be noted that when the device includes N reaction units, this invention does not limit whether any two reactors are of the same type. It can be selected that any two reactors are of the same or different types. In a further example of this invention, the reactors in the N reaction units are of the same type, thereby improving the overall operability of the process.

[0053] Example 4

[0054] A method for producing propylene oxide via direct hydrogen peroxide oxidation, the method in this embodiment employs... Figure 4 The unit shown is in operation, with a propylene oxide production capacity of 150,000 tons.

[0055] Specifically, the molar ratio of methanol:propylene:hydrogen peroxide in the first reactor 11 is 6.2:3:1. The first reactor 11 is loaded at 50% of its total capacity, with a methanol feed rate of 34.6 t / h, a 50% hydrogen peroxide aqueous solution feed rate of 12.3 t / h, a propylene feed rate of 15.6 t / h, and a propylene-rich phase return rate of 10.1 t / h from the first liquid-liquid phase separator 21. The first reactor 11 is a tubular fixed-bed reactor equipped with a liquid distribution device for mixing the feed materials. The epoxidation reaction is carried out at 45°C and 2.4 MPaG under the catalysis of titanium-silicon molecular sieve TS-1 (titanium-silicon ratio of SiO2:TiO2 = 25); the mass hourly space velocity of the catalyst is 0.3 h⁻¹. -1 .

[0056] The effluent from the first reactor 11 is cooled to 35°C by the first discharge cooler 31 and then enters the first liquid-liquid phase separation device 21 for phase separation. The resulting propylene-rich phase has a flow rate of 10.1 t / h, with propylene, methanol, and propylene oxide mass contents of 70.2%, 13.9%, and 15.9%, respectively, and is returned to the inlet of the first reactor 11. The resulting solvent-rich phase has a flow rate of 62.6 t / h, with methanol, water, propylene, and propylene oxide mass contents of 55.1%, 14.7%, 13.8%, and 15.3%, respectively, as well as some other impurities. This solvent-rich phase enters the second reactor 12 of the second reaction unit to continue the reaction.

[0057] The molar ratio of methanol:propylene:hydrogen peroxide in the second reactor 12 is 5.8:3:1. The feed flow rate of 50% hydrogen peroxide aqueous solution is 12.3 t / h, the feed flow rate of propylene is 7.6 t / h, the flow rate of the solvent-rich phase from the first reaction unit is 62.6 t / h, and the flow rate of the propylene-rich phase returned from the second liquid-liquid phase separation device 21 is 11.1 t / h. The second reactor 12 is a tubular fixed-bed reactor equipped with a liquid distribution device. The epoxidation reaction is carried out at 45℃ and 2.4 MPaG under the catalysis of titanium-silicon molecular sieve TS-1 (titanium-silicon ratio SiO2:TiO2 = 25); the mass hourly space velocity of the catalyst is 0.3 h⁻¹. -1 .

[0058] The effluent from the second reactor 12 is cooled to 35°C by the second discharge cooler 32 and then enters the second liquid-liquid phase separator 21 for phase separation. The propylene-rich phase has a flow rate of 11.1 t / h, with propylene, methanol, and propylene oxide mass contents of 69.9%, 12.6%, and 17.5%, respectively, and is returned to the inlet of the second reactor 12. The solvent-rich phase has a flow rate of 82.5 t / h, with methanol, water, propylene, and propylene oxide mass contents of 41.6%, 22.4%, 10.6%, and 23.8%, respectively, and enters the subsequent separation process to separate methanol, propylene, and propylene oxide products.

[0059] In this embodiment, the final product of propylene oxide is 18.75 t / h; the purified methanol and propylene are recycled back to the reaction unit at flow rates of 34.4 t / h and 9.0 t / h, respectively (excluding separation losses). In the subsequent separation process, the 2.5 MPaG steam consumption of the methanol double-effect separator is 35.7 t / h, and the 0.5 MPaG steam consumption of the propylene separator is 2.57 t / h.

[0060] Example 5

[0061] A method for producing propylene oxide via direct hydrogen peroxide oxidation, the method in this embodiment employs... Figure 3 The unit shown is in operation, with a propylene oxide production capacity of 150,000 tons.

[0062] Specifically, the molar ratio of methanol:propylene:hydrogen peroxide in the first reactor 11 is 6.2:3:1. The first reactor 11 is loaded at 50% of its total capacity, with a methanol feed rate of 35.0 t / h, a 50% hydrogen peroxide aqueous solution feed rate of 12.3 t / h, a propylene feed rate of 19.1 t / h, and a propylene-rich phase return rate of 5.3 t / h from the first liquid-liquid phase separator 21. The first reactor 11 is a tubular fixed-bed reactor equipped with a liquid distribution device for mixing the feed materials. The epoxidation reaction is carried out at 50°C and 2.8 MPaG under the catalysis of titanium-silicon molecular sieve TS-1 (titanium-silicon ratio of SiO2:TiO2 = 25); the mass hourly space velocity of the catalyst is 0.3 h⁻¹. -1 .

[0063] The effluent from the first reactor 11 enters the first liquid-liquid phase separation device 21 for phase separation, resulting in a propylene-rich phase with a flow rate of 5.3 t / h, of which the mass contents of propylene, methanol, and propylene oxide are 68.3%, 15.3%, and 16.4%, respectively, and is returned to the inlet of the first reactor 11. The phase separation also yields a solvent-rich phase with a flow rate of 66.4 t / h, of which the mass contents of methanol, water, propylene, and propylene oxide are 52.6%, 13.8%, 18.2%, and 14.3%, respectively. This solvent-rich phase enters the second reactor 12 of the second reaction unit to continue the reaction.

[0064] The molar ratio of methanol:propylene:hydrogen peroxide in the second reactor 12 is 5.8:3:1. The feed flow rate of 50% hydrogen peroxide aqueous solution is 12.3 t / h, the feed flow rate of propylene is 8.1 t / h, the flow rate of the solvent-rich phase from the first reaction unit is 66.4 t / h, and the flow rate of the propylene-rich phase returned from the second liquid-liquid phase separation device 21 is 6.5 t / h. The second reactor 12 is a tubular fixed-bed reactor equipped with a liquid distribution device. The epoxidation reaction is carried out at 50℃ and 2.8 MPaG under the catalysis of titanium-silicon molecular sieve TS-1 (titanium-silicon ratio SiO2:TiO2 = 25); the mass hourly space velocity of the catalyst is 0.3 h⁻¹. -1 .

[0065] The effluent from the second reactor 12 enters the second liquid-liquid phase separator 21 for phase separation. The propylene-rich phase has a flow rate of 6.5 t / h, with propylene, methanol, and propylene oxide content of 68.1%, 13.6%, and 18.3% by mass, respectively, and returns to the inlet of the second reactor 12. The solvent-rich phase has a flow rate of 86.8 t / h, with methanol, water, propylene, and propylene oxide content of 40.1%, 21.4%, 14.5%, and 22.6% by mass, respectively, along with some other impurities, and enters the subsequent separation unit to separate methanol, propylene, and propylene oxide products.

[0066] In this embodiment, the final product of propylene oxide is 18.75 t / h; the purified methanol and propylene are recycled back to the reaction unit at flow rates of 34.7 t / h and 12.6 t / h, respectively (excluding separation losses). In the subsequent separation process, the 2.5 MPaG steam consumption of the methanol double-effect separator is 36.1 t / h, and the 0.5 MPaG steam consumption of the propylene separator is 3.60 t / h.

[0067] It should be noted that the above description is a further detailed explanation of the present invention in conjunction with specific embodiments, and should not be construed as limiting the specific implementation of the present invention to these descriptions. For those skilled in the art, several simple improvements can be made without departing from the concept of the present invention, and all such improvements should be considered to fall within the scope of protection of the present invention.

Claims

1. An apparatus for producing propylene oxide via direct hydrogen peroxide oxidation, characterized in that, The device is a single reaction unit or comprises N reaction units connected in series, where N is at least 2. The reaction unit includes a reactor and a liquid-liquid phase separation device. The reactor is used to react propylene with hydrogen peroxide under the action of a catalyst to obtain propylene oxide. The liquid-liquid phase separation device is used to separate the material after the reaction in the reactor into a liquid-liquid phase and a solvent-rich phase. When the device is a single reaction unit, the reactor is connected to a solvent input pipe, a hydrogen peroxide input pipe, and a propylene input pipe, and the reactor outlet is connected to the inlet of the liquid-liquid phase separator; the propylene-rich phase outlet of the liquid-liquid phase separator is connected to the inlet of the reactor, and the solvent-rich phase outlet of the liquid-liquid phase separator is connected to the subsequent separation unit. When the device comprises N reaction units connected in series, the inlet of the reactor in the first reaction unit is connected to the solvent input pipe, the inlet of the reactor in any reaction unit is connected to the hydrogen peroxide input pipe and the propylene input pipe, and the outlet is connected to the inlet of the liquid-liquid phase separator; the propylene-rich outlet of the liquid-liquid phase separator in any reaction unit is connected to the inlet of the reactor in the same reaction unit, the solvent-rich phase outlet of the liquid-liquid phase separator in the next stage reaction unit is connected to the inlet of the reactor in the next stage reaction unit, and the solvent-rich phase outlet of the liquid-liquid phase separator in the last stage reaction unit is connected to the subsequent separation unit.

2. The apparatus for producing propylene oxide by direct oxidation with hydrogen peroxide according to claim 1, characterized in that, The reactor for any reaction unit can be independently selected from tubular reactors, batch reactors, or tower reactors.

3. The apparatus for producing propylene oxide by direct oxidation with hydrogen peroxide according to claim 2, characterized in that, The reactors in the N reaction units are of the same type.

4. The apparatus for producing propylene oxide by direct hydrogen peroxide oxidation according to claim 1, characterized in that, The reactor in any reaction unit is a tubular reactor.

5. The apparatus for producing propylene oxide by direct hydrogen peroxide oxidation according to claim 1, characterized in that, A liquid distribution device is provided in any of the reaction units.

6. The apparatus for producing propylene oxide by direct hydrogen peroxide oxidation according to claim 1, characterized in that, In any of the aforementioned reaction units, a cooler is installed on the pipeline connecting the reactor outlet and the liquid-liquid phase separation device inlet.

7. The apparatus for producing propylene oxide by direct hydrogen peroxide oxidation according to claim 1, characterized in that, Within any of the reaction units, a filtration device is installed on the pipeline connecting the reactor outlet and the liquid-liquid phase separator inlet.

8. The apparatus for producing propylene oxide by direct oxidation with hydrogen peroxide according to claim 1, characterized in that, The reactor and liquid-liquid phase separation device within the same reaction unit can be integrated or separate devices.

9. The apparatus for producing propylene oxide by direct hydrogen peroxide oxidation according to claim 1, characterized in that, The liquid-liquid phase separation device can be a static phase separation device or a dynamic separation device.

10. The apparatus for producing propylene oxide by direct oxidation with hydrogen peroxide according to claim 9, characterized in that, The liquid-liquid phase separation device is a static phase separation device.

Images