Device for producing epoxypropane by hydrogen peroxide direct oxidation method

Abstract

The invention relates to the technical field of chemical synthesis, and provides a device for producing epoxypropane by a hydrogen peroxide direct oxidation method, the device 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 method reduces the circulation volume of propylene and the solvent in the 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 present invention relates to the technical field of chemical synthesis, and particularly relates to a device for producing propylene oxide by a direct oxidation method of hydrogen peroxide. Background Art

[0002] Propylene oxide (PO) is an important basic organic chemical raw material and is the third largest propylene derivative after polypropylene and acrylonitrile. It is mainly used to produce chemical products such as polyether polyols, propylene glycol, and propylene glycol ethers, and is widely used in fields such as thermal insulation materials, building materials, automobiles, food, medicine, cosmetics, coatings, and adhesives. 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, the preparation process of propylene oxide has developed rapidly. Among them, the direct oxidation method of hydrogen peroxide to produce propylene oxide (HPPO) has the advantages of simple process, small environmental impact, mild reaction conditions, and high raw material utilization efficiency, and is gradually replacing the traditional production process of propylene oxide.

[0004] In the HPPO process, under relatively mild conditions, propylene and hydrogen peroxide react directly in a reactor under the catalysis of titanium silicalite (TS-1) in a circulating solvent. A large number of studies have been carried out on the HPPO process at home and abroad. For example, Patent US2003009040A1 discloses an olefin epoxidation process that uses a multiphase mixing system composed of a liquid phase rich in hydrogen peroxide and solvent and an organic liquid phase rich in propylene, which can significantly improve the selectivity of propylene oxide without affecting the conversion rate of hydrogen peroxide, but this patent does not involve the subsequent separation process of the two-phase system. Patent CN103641800A discloses a method for producing propylene oxide, which involves 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. By maintaining the molar ratio of methanol / propylene / hydrogen peroxide input to a single reactor, the excess propylene and methanol in the first reactor are recycled in the second reactor, reducing the propylene circulation amount and methanol circulation amount, but the final reaction stream still needs to be separated from the solvent and propylene by energy-consuming methods such as distillation and then recycled back to the reactor. Patent CN101693703A discloses an energy-saving and emission-reduction process for epoxidizing propylene with hydrogen peroxide. Propylene and hydrogen peroxide undergo an epoxidation reaction under the action of titanium silicalite at medium pressure and low temperature. The unreacted propylene in the reaction product is separated in a propylene distillation column, and the circulating solvent is separated at the top of the solvent distillation column; although the bottom stream of the propylene column is used as part of the heat source for the subsequent distillation column to recover some energy, a large amount of fresh steam is still consumed in the separation process.

[0005] It should be noted that in the actual process, to improve the conversion rate of hydrogen peroxide and the yield of propylene oxide, reduce potential safety hazards such as combustion and explosion, and suppress side reactions, in addition to using a highly selective catalyst, an excessive amount of propylene and a large amount of recycled solvent should also be provided. In the subsequent reaction product separation process, complex procedures are required to separately separate and purify the excessive propylene and solvent and then return them to the epoxidation reactor for recycling. This separation is mainly carried out by distillation, which consumes a large amount of energy and seriously affects the economic efficiency of the process. Summary of the Invention

[0006] Aiming at the deficiencies in the prior art, the present invention discloses a device for producing propylene oxide by the direct oxidation of hydrogen peroxide. The device has a high conversion rate of hydrogen peroxide and a high yield of propylene oxide, resulting in a lower circulation volume of propylene and solvent in the subsequent separation process, operating safely and stably, saving energy and reducing consumption, and being suitable for large-scale popularization and application.

[0007] To achieve the above technical objectives, on the one hand, the present invention proposes a device for producing propylene oxide by the direct oxidation of hydrogen peroxide. The device is a single reaction unit or includes N series-connected reaction units, where N is at least 2;

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

[0009] 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. The outlet of the reactor is connected to the inlet of the liquid-liquid phase separation device; the propylene-rich phase outlet of the liquid-liquid phase separation device is connected to the inlet of the reactor, and the solvent-rich phase outlet of the liquid-liquid phase separation device is connected to the subsequent separation unit;

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

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

[0012] In the above technical solution, within 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 under the action of a catalyst in the reactor:

[0013] CH 3 CH=CH 2 +H 2 O 2 →CH 3 CH(O)CH 2 +H 2 O

[0014] The reacted material is fed into a liquid-liquid phase separator for phase separation to obtain a propylene-rich phase and a solvent-rich phase. The propylene-rich phase includes propylene, solvent, and propylene oxide, with the highest mass proportion being that of propylene. The solvent-rich phase includes methanol, water, propylene, and propylene oxide, with the highest mass proportion being that of the solvent. 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, which can effectively reduce the circulation amounts 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 fed into the subsequent separation process to separate the product, solvent, propylene, and remove water, and the phase separation operation enriches the propylene oxide in the solvent-rich phase, thereby further reducing the operation difficulty of the subsequent separation process and saving energy and reducing consumption. When the epoxidation reaction is carried out in N reaction units, the propylene-rich phases obtained after phase separation in each reaction section are returned, reducing the proportion of propylene and solvent in the solvent-rich phase output from the liquid-liquid phase separator of the last reaction unit, thereby reducing the load of the subsequent separation unit and reducing energy consumption. In addition, through a series of multiple reaction units, the excessive solvent and propylene in the previous group of reaction units are continuously fed into the subsequent group of reaction units in the form of a solvent-rich phase, reducing the input amounts of fresh propylene and solvent in the subsequent group of reaction units, thereby generally reducing the flow rates of propylene and solvent entering the subsequent separation process, further reducing the energy consumption of the subsequent separation process and reducing the separation difficulty.

[0015] Examples and comparative examples of the present invention illustrate the process of producing propylene oxide by the direct oxidation of hydrogen peroxide method including a single reaction unit and N reaction units.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0017] The device for producing propylene oxide by the direct oxidation of hydrogen peroxide method of the present invention uses a liquid-liquid phase separator in each reaction unit to perform liquid-liquid phase separation on the material output from the reactor in each reaction unit, returns the propylene-rich phase to the reactor for continuous reaction, and feeds the solvent-rich phase into the reactor of the next-stage reaction unit for continuous reaction. The solvent-rich phase output from the liquid-liquid phase separator in the last reaction unit is fed into the subsequent separation process, thereby recycling most of the propylene and part of the solvent in the reacted material, reducing the circulation amounts of propylene and solvent in the subsequent separation process, increasing the content of propylene oxide in the material input into the separation unit, and further reducing the energy consumption of the subsequent separation unit, achieving significant economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The specification drawings forming a part of this application are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0019] Figure 1Shows a structural diagram of the device for producing propylene oxide by the direct oxidation method of hydrogen peroxide according to the present invention;

[0020] Figure 2 Shows another structural diagram of the device for producing propylene oxide by the direct oxidation method of hydrogen peroxide according to the present invention;

[0021] Figure 3 Shows another structural diagram of the device for producing propylene oxide by the direct oxidation method of hydrogen peroxide according to the present invention;

[0022] Figure 4 Shows another structural diagram of the device for producing propylene oxide by the direct oxidation method of hydrogen peroxide according to the present invention.

[0023] Among them, the above-mentioned drawings include the following reference numerals:

[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 implementation manners

[0025] For the convenience of understanding the present invention, the present invention will be described more comprehensively below, and preferred embodiments of the present invention are given. However, it should be understood that these embodiments are only for more detailed description and should not be construed as limiting the present invention in any form, that is, it is not intended to limit the protection scope of the present invention.

[0026] Unless otherwise defined, the technical terms used in the following embodiments have the same meanings as commonly understood by those skilled in the art to which the present invention pertains. The test reagents used in the following embodiments are all conventional biochemical reagents unless otherwise specified; the experimental methods used are all conventional methods unless otherwise specified.

[0027] Embodiment 1

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

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

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

[0031] The present invention does not limit the position where the reaction materials are input into the reactor 1. In a further example of the present invention, the reactor 1 is fed from the top, bottom, or side, and the appropriate feeding position is selected according to needs in the specific process.

[0032] Furthermore, a liquid distribution device is provided in any one of the reaction units to uniformly distribute the liquid of the materials input into the reactor 1, thereby promoting the uniform mixing and full contact of the reactants. It should be noted that the present invention does not limit the specific structure of the liquid distribution device, and those skilled in the art can select a device or arrangement that can promote the distribution of two-phase or multi-phase liquids according to needs, and the protection scope of the present invention is not limited thereby.

[0033] Furthermore, in any one of the reaction units, a cooler 3 and / or a filtering device are provided on the pipeline connecting the outlet of the reactor 1 and the inlet of the liquid-liquid phase separation device 2, so that under specific working conditions, the temperature of the materials output from the reactor 1 can be adjusted by the cooler 3 to improve the efficiency of subsequent phase separation operations, or the entrained catalyst particles can be separated by the filtering device to protect the stability of the downstream settings and the operation of the device. Figure 2 Fig. shows a structure of the device for producing propylene oxide by the direct oxidation method of hydrogen peroxide of the present invention including a cooler.

[0034] Furthermore, the reactor 1 and the liquid-liquid phase separation device 2 in the same reaction unit are an integrated device or a split device. In the actual process, the reactor 1 and the liquid-liquid phase separation device 2 can be selected to be split according to needs, or operated in the form of an integrated device, which can meet the needs of more working conditions.

[0035] Furthermore, the liquid-liquid phase separation device 2 can be selected as a static phase separation device or a dynamic separation device, which can be selected by those skilled in the art according to needs. In an optional example of the present invention, the liquid-liquid phase separation device 2 is preferably a static phase separation device.

[0036] Example 2

[0037] A method for producing propylene oxide by the direct oxidation method of hydrogen peroxide. The method of this example uses Figure 2 the device shown in Fig. to operate, and the production scale of propylene oxide is 150,000 tons.

[0038] Specifically: The molar ratio of methanol:propylene:hydrogen peroxide in reactor 1 is 6.2:3:1, where the methanol feed flow rate is 69.2 t / h, the feed flow rate of 50% aqueous hydrogen peroxide solution is 24.6 t / h, the propylene feed flow rate is 31.5 t / h, and the flow rate of the propylene-rich phase returned from the liquid-liquid phase separation device 2 is 20.2 t / h. Reactor 1 is a shell-and-tube fixed-bed reactor, equipped with a liquid distribution device for evenly distributing the feed materials. Subsequently, inside reactor 1, under the catalysis of titanium silicate molecular sieve TS-1 (titanium-silicon ratio SiO 2 :TiO 2 =25), the epoxidation reaction is carried out at 45 °C and 2.4 MPaG; the mass space velocity of the catalyst is 0.05 - 1.2 h -1 .

[0039] The outlet stream of reactor 1 is cooled to 35 °C by the outlet cooler 3 and enters the liquid-liquid phase separation device 2 for phase separation; the flow rate of the separated propylene-rich phase 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 separation by the subsequent separation unit, the final propylene oxide product of this example is 18.75 t / h. The separated and purified methanol and propylene are recycled back to the reaction unit for continuous reaction, and the recycle flow rates are 68.9 t / h and 17.3 t / h respectively (excluding separation losses). The subsequent separation unit of this example includes a methanol two-effect separation tower and a propylene separation tower. Among them, the steam consumption of the methanol two-effect separation tower is 59.7 t / h for 2.5 MPaG steam, and the steam consumption of the propylene separation tower is 4.93 t / h for 0.5 MPaG steam.

[0041] Comparative Example 1

[0042] This comparative example shows a process for directly oxidizing 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 is 6.2:3:1, where the methanol feed flow rate is 72.0 t / h, the feed flow rate of 50% aqueous hydrogen peroxide solution is 24.6 t / h, and the propylene feed flow rate is 45.7 t / h. The reactor is a shell-and-tube fixed-bed reactor, equipped with a liquid distribution device for mixing the feed materials of the reactor. Inside the reactor, under the catalysis of titanium silicate molecular sieve TS-1 (titanium-silicon ratio SiO 2 :TiO 2Under the catalysis of [[ID=]], the epoxidation reaction was carried out at 45 °C and 2.4 MPaG; the mass hourly space velocity of the catalyst was the same as that of the catalyst in Example 2.

[0044] The reactor outlet stream was cooled to 35 °C by the product cooler 3 and then entered the liquid-liquid phase separation unit 2 for phase separation. The flow rate of the propylene-rich phase obtained by separation was 19.8 t / h, and the mass contents of propylene, methanol, and propylene oxide were 71.8%, 14.3%, and 13.9% respectively; the flow rate of the solvent-rich phase was 122.4 t / h, and the mass contents of methanol, water, propylene, and propylene oxide were 56.4%, 14.9%, 14.2%, and 13.3% respectively, as well as some other impurities. The propylene-rich phase stream and the solvent-rich phase stream both entered the subsequent separation unit to separate methanol, propylene, and propylene oxide products.

[0045] In this comparative example, the final product of propylene oxide was 18.75 t / h, and the purified methanol and propylene were recycled back to the reaction unit, with the recycle flow rates being 71.7 t / h and 31.5 t / h respectively (excluding separation losses). The subsequent separation unit included a methanol double-effect separation column and a propylene separation column. The steam consumption of the methanol double-effect separation column was 61.7 t / h for 2.5 MPaG steam, and the steam consumption of the propylene separation column was 8.98 t / h for 0.5 MPaG steam.

[0046] Combining Example 2 and Comparative Example 1, it can be verified that in order to achieve the same propylene oxide yield, the process of Comparative Example 1 needs to increase the input of propylene and solvent methanol; at the same time, after the reaction is completed, 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 speculated that the subsequent separation process of Comparative Example 1 will consume more energy. By comparing and analyzing the energy consumption of the distillation columns in the subsequent separation processes of Example 1 and Comparative Example 1, it is confirmed that the method for producing propylene oxide by the direct oxidation of hydrogen peroxide in this Example 1 can significantly reduce the energy consumption of the process operation and operate stably and safely.

[0047] Example 3

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

[0049] Among them, the feed inlet of the reactor 1 in the first reaction unit is connected to the solvent input pipe, the feed inlet of the 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 the liquid-liquid phase separation device 2; the rich propylene outlet of the liquid-liquid phase separation device 2 in any reaction unit is connected to the feed inlet of the reactor 1 in the same reaction unit, the rich solvent phase outlet of the liquid-liquid phase separation device 2 in the upper-stage reaction unit is connected to the feed inlet of the reactor 1 in the lower-stage reaction unit, and the rich solvent phase outlet of the liquid-liquid phase separation device 2 in the last-stage reaction unit is connected to the subsequent separation unit.

[0050] Figure 3 The figure shows an example of the device for producing propylene oxide by the direct oxidation method of hydrogen peroxide in this embodiment including 2 reaction units. As shown in the figure, the raw materials hydrogen peroxide and propylene, and the solvent are input into the first reactor 11 in the first reaction unit for epoxidation reaction, and the reacted materials are input into the first liquid-liquid phase separation device 21 for phase separation; the separated rich propylene phase is returned to the feed inlet of the first reactor 11, and the obtained rich solvent phase is input into the second reactor 12 in the second reaction unit; the newly input hydrogen peroxide and propylene undergo an epoxidation reaction in the second reactor 12, and the reacted materials are input into the second liquid-liquid phase separation device 21 for phase separation. The separated rich propylene phase is returned to the feed inlet of the second reactor 12, and the obtained rich solvent phase is input into the subsequent separation unit.

[0051] Figure 4 The figure shows a device for producing propylene oxide by the direct oxidation method of hydrogen peroxide including a first cooler 31 and a second cooler 32. Specifically, the reacted materials output from the first reactor 11 are cooled by the first cooler 31 and then input into the first liquid-liquid phase separation device 21, and the reacted materials output from the second reactor 12 are cooled by the second cooler 32 and then input into the second liquid-liquid phase separation device 21.

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

[0053] Example 4

[0054] A method for producing propylene oxide by the direct oxidation method of hydrogen peroxide. The method in this embodiment uses Figure 4 the device shown in the figure to operate, and the production scale of propylene oxide is 150,000 tons.

[0055] Specifically: The molar ratio of methanol:propylene:hydrogen peroxide in the first reactor 11 is 6.2:3:1. The load of the first reactor 11 is 50% of the total amount. Among them, the methanol feed flow rate is 34.6 t / h, the 50% aqueous hydrogen peroxide solution feed flow rate is 12.3 t / h, the propylene feed flow rate is 15.6 t / h, and the propylene-rich phase flow rate returned from the first liquid-liquid phase separation device 21 is 10.1 t / h. The first reactor 11 is a shell-and-tube fixed-bed reactor, equipped with a liquid distribution device for mixing the feed materials. Under the catalytic action of titanium silicalite TS-1 (the titanium-silicon ratio is SiO 2 :TiO 2 =25), the epoxidation reaction is carried out at 45°C and 2.4 MPaG; the mass hourly space velocity of the catalyst is 0.3 h -1 .

[0056] The outlet stream of the first reactor 11 is cooled to 35°C by the first cooler 31 for discharging and then enters the first liquid-liquid phase separation device 21 for phase separation. The obtained propylene-rich phase has a flow rate of 10.1 t / h, in which the mass contents of propylene, methanol, and propylene oxide are 70.2%, 13.9%, and 15.9% respectively, and it returns to the inlet of the first reactor 11; the obtained solvent-rich phase has a flow rate of 62.6 t / h, in which the mass contents of methanol, water, propylene, and propylene oxide are 55.1%, 14.7%, 13.8%, and 15.3% respectively, and some other impurities. This part of the 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 50% aqueous hydrogen peroxide solution feed flow rate is 12.3 t / h, the propylene feed flow rate is 7.6 t / h, the flow rate of the solvent-rich phase sent 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 shell-and-tube fixed-bed reactor, equipped with a liquid distribution device. Under the catalytic action of titanium silicalite TS-1 (the titanium-silicon ratio is SiO 2 :TiO 2 =25), the epoxidation reaction is carried out at 45°C and 2.4 MPaG; the mass hourly space velocity of the catalyst is 0.3 h -1 .

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

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

[0060] Example 5

[0061] A method for producing propylene oxide by the direct oxidation of hydrogen peroxide. The method of this example uses Figure 3 the device shown to operate, and the production scale of propylene oxide is 150,000 tons.

[0062] Specifically: In the first reactor 11, the molar ratio of methanol:propylene:hydrogen peroxide is 6.2:3:1. The load of the first reactor 11 is 50% of the total amount, where the methanol feed flow rate is 35.0 t / h, the 50% aqueous hydrogen peroxide feed flow rate is 12.3 t / h, the propylene feed flow rate is 19.1 t / h, and the flow rate of the propylene-rich phase returned from the first liquid-liquid phase separation device 21 is 5.3 t / h. The first reactor 11 is a shell-and-tube fixed-bed reactor, equipped with a liquid distribution device for mixing the feed materials. Under the catalytic action of titanium silicalite TS-1 (the titanium-silicon ratio is SiO 2 :TiO 2 = 25), the epoxidation reaction is carried out at 50 °C and 2.8 MPaG; the mass space velocity of the catalyst is 0.3 h -1 .

[0063] The outlet stream of the first reactor 11 enters the first liquid-liquid phase separation device 21 for phase separation, and the flow rate of the obtained propylene-rich phase is 5.3 t / h, where the mass contents of propylene, methanol, and propylene oxide are 68.3%, 15.3%, and 16.4% respectively, which is returned to the inlet of the first reactor 11; the flow rate of the solvent-rich phase obtained by phase separation is 66.4 t / h, where the mass contents of methanol, water, propylene, and propylene oxide are 52.6%, 13.8%, 18.2%, and 14.3% respectively. This part of the solvent-rich phase enters the second reactor 12 of the second reaction unit to continue the reaction.

[0064] In the second reactor 12, the molar ratio of methanol:propylene:hydrogen peroxide is 5.8:3:1. The feed flow rate of the 50% aqueous hydrogen peroxide solution is 12.3 t / h, the feed flow rate of propylene is 8.1 t / h, the flow rate of the rich solvent phase sent from the first reaction unit is 66.4 t / h, and the flow rate of the rich propylene phase returned from the second liquid-liquid phase separation device 21 is 6.5 t / h. The second reactor 12 is a shell-and-tube fixed-bed reactor, equipped with a liquid distribution device. Under the catalysis of titanium silicalite TS-1 (titanium-silicon ratio SiO 2 :TiO 2 = 25), the epoxidation reaction is carried out at 50 °C and 2.8 MPaG; the mass hourly space velocity of the catalyst is 0.3 h -1 .

[0065] The outlet stream of the second reactor 12 enters the second liquid-liquid phase separation device 21 for phase separation. The flow rate of the rich propylene phase is 6.5 t / h, in which the mass contents of propylene, methanol, and propylene oxide are 68.1%, 13.6%, and 18.3% respectively, and it returns to the inlet of the second reactor 12; the flow rate of the rich solvent phase is 86.8 t / h, in which the mass contents of methanol, water, propylene, and propylene oxide are 40.1%, 21.4%, 14.5%, and 22.6% respectively, and some other impurities enter the subsequent separation unit to separate methanol, propylene, and propylene oxide products.

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

[0067] It should be noted that the above content is a further detailed description of the present invention in combination with specific embodiments, and it cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those of ordinary skill in the technical field to which the present invention belongs, without departing from the concept of the present invention, several simple improvements can be made, and all of them should be regarded as belonging to the scope of protection of the present invention.

Claims

1. A device for producing propylene oxide by direct oxidation of hydrogen peroxide, characterized in that: The device is a single reaction unit or comprises N reaction units connected in series, N being at least 2; The reaction unit comprises a reactor and a liquid-liquid phase separation device, wherein the reactor is used for reacting propylene with hydrogen peroxide under the action of a catalyst to obtain propylene oxide, and the liquid-liquid phase separation device is used for liquid-liquid phase separation of the materials after the reaction in the reactor to obtain a propylene-rich 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 discharge port of the reactor is connected to the feed port of the liquid-liquid phase separation device; the propylene-rich phase outlet of the liquid-liquid phase separation device is connected to the feed port of the reactor, and the solvent-rich phase outlet of the liquid-liquid phase separation device is connected to a subsequent separation unit; When the device includes N reaction units connected in series, the feed inlet of the reactor in the first reaction unit is connected to the solvent input pipe, the feed inlet of the reactor in any reaction unit is connected to the hydrogen peroxide input pipe and the propylene input pipe, and the discharge port is connected to the feed inlet of the liquid-liquid phase separation device; the propylene-rich outlet of the liquid-liquid phase separation device in any reaction unit is connected to the feed inlet of the reactor in the same reaction unit, the solvent-rich phase outlet of the liquid-liquid phase separation device in the upper-stage reaction unit is connected to the feed inlet of the reactor in the lower-stage reaction unit, and the solvent-rich phase outlet of the liquid-liquid phase separation device in the last-stage reaction unit is connected to the subsequent separation unit.

2. The device for producing propylene oxide by direct oxidation of hydrogen peroxide according to claim 1, characterized in that: The reactor of any reaction unit is independently selected from a shell-and-tube reactor, a tank reactor or a tower reactor.

3. The device for producing propylene oxide by direct oxidation of hydrogen peroxide according to claim 2, characterized in that: The reactor types in the N reaction units are the same.

4. The device for producing propylene oxide by direct oxidation of hydrogen peroxide according to claim 1, characterized in that: The reactor of any reaction unit is a shell-and-tube reactor.

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

6. The device for producing propylene oxide by direct oxidation of hydrogen peroxide according to claim 1, characterized in that: In any of the reaction units, a cooler is arranged on the pipeline connecting the discharge port of the reactor and the feed port of the liquid-liquid phase separation device.

7. The device for producing propylene oxide by direct oxidation of hydrogen peroxide according to claim 1, characterized in that: In any of the reaction units, a filtering device is arranged on the pipeline connecting the discharge port of the reactor and the feed port of the liquid-liquid phase separation device.

8. The device for producing propylene oxide by direct oxidation of hydrogen peroxide according to claim 1, characterized in that: The reactor and the liquid-liquid phase separation device in the same reaction unit are integrated equipment or separate equipment.

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

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

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