CN115197171A - A kind of method and system for producing propylene oxide - Google Patents

Abstract

Propylene and hydrogen peroxide are mixed and contacted in a reactor in the presence of an oxidation catalyst to carry out oxidation reaction, and the material flow after the reaction is separated to obtain the propylene oxide; the adopted device for producing the propylene oxide consists of a riser reactor (5), a liquid-solid separator (8), a liquid-liquid separator (13) and a tubular mixer (4), wherein the top of the reactor is communicated with the inlet of the solid-liquid separator through an external circulating pipe (7), the intercepted liquid outlet of the solid-liquid separator is communicated with the bottom of the reactor through the external circulating pipe and the tubular mixer, and the clear liquid outlet (10) of the solid-liquid separator is communicated with the inlet of the liquid-liquid separator; the hydrogen peroxide and the solvent in the reaction mass are used as a dispersed phase or a continuous phase. The method for producing the propylene oxide strengthens liquid-liquid mass transfer, can improve the reaction conversion rate and selectivity, and realizes long-period operation of the device.

Description

A kind of method and system for producing propylene oxide

technical field

The invention relates to a method and reaction system for producing propylene oxide, more particularly, to a method and reaction system for catalyzing the oxidation of propylene with hydrogen peroxide to produce propylene oxide using a liquid-liquid-solid multiphase reaction device.

technical background

Propylene oxide (PO) is an important basic organic chemical raw material. It is the third largest organic chemical product in propylene derivatives after polypropylene and acrylonitrile. It is widely used in chemical industry, light industry, medicine, food, Textile and other industries have a profound impact on the chemical industry and the development of the national economy. With the expansion of PO uses and the growth of downstream product consumption, the demand for PO market is increasing. At present, the industrial production of propylene oxide mainly adopts the chlorohydrin method and the co-oxidation method. When the chlorohydrin method is used to synthesize propylene oxide, the equipment is seriously corroded, a large amount of toxic gas is consumed, and a large amount of waste water is generated, which does not meet the requirements of green chemistry and clean production, and will be gradually eliminated. And by-products are subject to market constraints. Using titanium-silicon molecular sieve as a catalyst, hydrogen peroxide directly epoxidizes propylene to synthesize propylene oxide (HPPO process). The process is mild, environmentally friendly and pollution-free. It conforms to the current development concept of green chemistry and is a green way to produce propylene oxide. New Technology.

Due to the poor compatibility of the reaction raw material propylene and hydrogen peroxide in the process of direct epoxidation of propylene with hydrogen peroxide to synthesize propylene oxide, the current methods for liquid-liquid mixing of oil and water phases mainly include the following: First, by adding cosolvents to improve the two mutual solubility. For example, CN 101293813A discloses a method for producing propylene oxide, which uses an emulsifier to form C4 and water into an oil-in-water emulsion and then performs olefin hydration reaction, which can increase the conversion rate of isobutene to about 70%. In the process of synthesizing propylene oxide from hydrogen peroxide and propylene, methanol is often used as a solvent to improve the mutual contact of two phases (CN102898405A, CN 102442979A, CN 106632148A), but the addition of such non-raw material may cause a series of side reactions occurrence, and has a great impact on the subsequent separation and product purity. In addition, the conventional methods for strengthening the liquid-liquid mixing process include mechanical stirring, designing tortuous flow channels, and high-speed impact of liquids. The purpose is to generate fluid turbulence to increase the mixing efficiency of liquids. Among them, the most commonly used form of reactor is a stirred tank, which uses the mechanical stirring action of a stirrer to realize the mixing and reaction of raw materials. However, due to the limitations of stirred tank equipment, the time scale of mixing is between a few minutes or even a few hours, which is often used in a reaction system with a slow reaction rate. For example, CN202527171A discloses a reaction device for gas-liquid-liquid-solid multiphase reaction. A guide tube is installed inside the reactor, and a stirrer is installed in the guide tube to realize the contact of raw materials by stirring. reaction. The commonly used pipeline static mixer uses a tortuous flow channel to strengthen the mixing of the fluid, but its mixing effect is relatively poor.

At present, the reactors used in the synthesis of propylene oxide from hydrogen peroxide and propylene mainly have the following forms, such as fixed bed reactors (EP 0659473, CN 1671678A) or tubular reactors, or a stirring method (CN101279957A) , or slurry bed reactor (CN 101314596A), or multiple reactors in series/parallel use, such as CN104311513A using a combined process of a fixed-bed pipeline reactor and a slurry-bed reactor, CN 106632148A discloses a drum The invention discloses a method for combining a bubble column slurry bed reactor and a stirred tank slurry bed reactor to carry out epoxidation reaction. The main purpose of the above-mentioned different methods is to improve the mass transfer between the phases and the heat extraction of the reaction. In order to solve the problem of heat release and process amplification in the chemical reaction process.

Judging from the reports in the existing literature and patents, the synthesis of propylene oxide from hydrogen peroxide and propylene still has many problems in the actual application process. Therefore, it is necessary to develop a new propylene epoxidation process, especially an innovative reactor form. , so as to simply and efficiently solve the problems of incomplete conversion of hydrogen peroxide, low effective utilization of hydrogen peroxide, low selectivity of product propylene oxide, and strong reaction heat in the process of synthesizing propylene oxide from hydrogen peroxide and propylene. May lead to flying temperature and many other problems.

SUMMARY OF THE INVENTION

One of the technical problems to be solved by the present invention is to provide a method for producing propylene oxide by oxidizing propylene with hydrogen peroxide in the presence of a solid molecular sieve catalyst.

The second technical problem to be solved by the present invention is to provide a reaction system for producing propylene oxide.

A method for producing propylene oxide, wherein propylene and hydrogen peroxide are mixed and contacted in a reactor in the presence of an oxidation catalyst to carry out an oxidation reaction, and after the reaction, the flow is separated to obtain propylene oxide; the adopted device for producing propylene oxide is reacted by a riser 5, liquid-solid separator 8, liquid-liquid separator 13 and tubular mixer 4, wherein, the bottom of the riser reactor is provided with a dispersed phase inlet 1 and a catalyst discharge outlet 6, and the top of the reactor is provided with a disperse phase inlet 1 and a catalyst discharge outlet 6. The inlet of the solid-liquid separator is communicated with the external circulation pipe 7, the retentate outlet of the solid-liquid separator is communicated with the bottom of the reactor through the external circulation pipe and the tubular mixer, and the clear liquid outlet 10 of the solid-liquid separator is connected with the The inlet of the liquid-liquid separator is connected, the liquid-liquid separator is provided with a water-phase outlet and an oil-phase outlet, and the water-phase outlet or the oil-phase outlet is communicated with the inlet of the tubular mixer 4 .

Preferably, hydrogen peroxide in the reaction mass is used as the dispersed phase, and propylene is used as the continuous phase.

A system for producing propylene oxide, comprising a device for producing propylene oxide, a reaction system composed of water-oil two-phase reaction raw materials and oxidation catalyst particles, wherein the water phase is hydrogen peroxide, with or without a solvent, and the oil phase is propylene, The particle size of the oxidation catalyst particles is 0.05-3.0 mm, and the device for producing propylene oxide is composed of a riser reactor 5, a liquid-solid separator 8, a liquid-liquid separator 13 and a tubular mixer 4, wherein , the bottom of the riser reactor is provided with a dispersed phase inlet 1 and a catalyst discharge outlet 6, the top of the reactor is connected to the inlet of the solid-liquid separator through an external circulation pipe 7, and the retentate outlet of the solid-liquid separator is externally circulated The tube and tube mixer are communicated with the bottom of the reactor, the clear liquid outlet 10 of the solid-liquid separator is communicated with the inlet of the liquid-liquid separator, and the liquid-liquid separator is provided with a water phase outlet and an oil phase outlet. The outlet, the water phase outlet or the oil phase outlet is communicated with the inlet of the tubular mixer 4 .

The novel multiphase reaction system provided by the present invention and its beneficial effects in the preparation process of propylene oxide are:

Compared with the prior art, the reaction method for directly oxidizing hydrogen peroxide to produce propylene oxide provided by the present invention adopts a special reaction device, and disperses one-phase reactants into tiny liquids through a dispersing phase feeder, and simultaneously adopts small particle size. Molecular sieve oxidation catalyst improves the mass transfer between phases through micro droplets and micro particles, thereby greatly improving the reaction efficiency, and does not require or minimize the use of co-solvents, reduces the occurrence of side reactions, and is also conducive to reducing the difficulty and energy consumption of subsequent separations. The coupling of the reaction and the (liquid-liquid) separation process is realized, a large amount of propylene realizes internal circulation, and the newly added propylene only needs to supplement the chemical consumption; in addition, the existence of high-concentration continuous phase propylene is beneficial to improve the hydrogen peroxide reaction selectivity. Since the solid-phase catalyst is in a circulating flow state in the reaction system, it is beneficial to the online renewal of the catalyst, thereby prolonging the shutdown and maintenance period of the device.

Description of drawings

1 is a schematic flow diagram of the first embodiment of the method for producing propylene oxide provided by the present invention.

Figure 2 is a schematic flow diagram of a second embodiment of a reaction apparatus for producing propylene oxide.

Description of reference numbers:

1-Disperse phase inlet 2-Continuous phase inlet 3-Disperse phase feeder

4-tubular mixer 5-reactor 6-catalyst discharge port

7-External circulation pipe 8-Liquid-solid separator 9-Lower section of external circulation pipe

10-clear liquid outlet 11-catalyst inlet 12-backwash liquid inlet

13-liquid-liquid separator 14-water phase outlet 15-oil phase outlet

16-Product separation system Ⅰ-tube side Ⅱ-shell side

Detailed ways

Specific embodiments of the present invention will be described in detail below.

A method for producing propylene oxide, wherein propylene and hydrogen peroxide are mixed and contacted in a reactor in the presence of an oxidation catalyst to carry out an oxidation reaction, and after the reaction, the flow is separated to obtain propylene oxide; the adopted device for producing propylene oxide is reacted by a riser 5, liquid-solid separator 8, liquid-liquid separator 13 and tubular mixer 4, wherein, the bottom of the riser reactor is provided with a dispersed phase inlet 1 and a catalyst discharge outlet 6, and the top of the reactor is provided with a disperse phase inlet 1 and a catalyst discharge outlet 6. The inlet of the solid-liquid separator is communicated with the external circulation pipe 7, the retentate outlet of the solid-liquid separator is communicated with the bottom of the reactor through the external circulation pipe and the tubular mixer, and the clear liquid outlet 10 of the solid-liquid separator is connected with the The inlet of the liquid-liquid separator is connected, the liquid-liquid separator is provided with a water-phase outlet and an oil-phase outlet, and the water-phase outlet or the oil-phase outlet is communicated with the inlet of the tubular mixer 4 .

In the method for producing propylene oxide provided by the present invention, hydrogen peroxide, with or without a solvent, is an aqueous phase, which can be used as a dispersed phase or a continuous phase; propylene is an oil phase as another phase. Preferably, hydrogen peroxide and solvent are used as the dispersed phase, and propylene is used as the continuous phase. The solvent is preferably methanol.

In the method for producing propylene oxide provided by the present invention, hydrogen peroxide and propylene undergo an oxidation reaction in the presence of an oxidation catalyst to obtain propylene oxide; the oxidation reaction conditions are: a pressure of 0.1-3.0 MPa, a temperature of 30-80° C., and a reaction residence time of 0.3- 3h, the molar ratio of fresh feed propylene and hydrogen peroxide is (1.0-3.0):1, and the molar ratio of solvent and hydrogen peroxide is (0-10):1. Preferably, a solvent is added to the reaction material, and the molar ratio of the solvent to the hydrogen peroxide is (0.5-10):1.

In the method for producing propylene oxide provided by the present invention, the oxidation catalyst is a titanium-silicon molecular sieve having an MFI structure, and the particle diameter of the oxidation catalyst is 0.05-3.0 mm.

In the method for producing propylene oxide provided by the present invention, in the device for producing propylene oxide, preferably, the riser reactor is divided into a tube side and a shell side, and the pipe body and the shell side are divided into a tube side and a shell side. The tubes are separated by the tube wall, the tube body and the shell are not connected, and the flow in the tube body and the shell can exchange heat, in which the tube side provides the reaction space for the reaction materials, and the shell side passes into the heat exchange medium to remove the heat released by the reaction, The upper and lower ends of the shell side are respectively provided with a heat exchange medium inlet and a heat exchange medium outlet.

In the device for producing propylene oxide, preferably, the dispersed phase inlet 1 is provided with a dispersed phase feeder 3, and the dispersed phase feeder is a porous tube, a sintered metal tube, an inorganic membrane tube or a Atomizing nozzle.

Preferably, the pressure drop before and after the dispersed phase feeder 2 is 0.05-3.0 MPa, and the initial liquid flow rate at the outlet of the dispersed phase feeder is 5-40 m/s.

Preferably, the riser reactor is a shell-and-tube reactor, wherein the inside of the tube side I provides a reaction space for the reaction material, and the cooling medium introduced into the shell side II conducts heat exchange with the reaction material in the tube side, so that the reaction Tropical out. The number of the tube side is preferably a plurality of circular tubes evenly arranged inside the reactor shell, and the tube side and the shell side materials are separated by setting top and bottom baffles. The disperse phase inlet is provided with a disperse phase feeder 2, and when there are multiple circular tubes in the straight pipe section, a disperse phase feeder is provided at the bottom of each circular tube. In the production of propylene oxide, the dispersed phase may be an oil phase or an aqueous phase. The dispersed phase feeder has a significant throttling effect, and it is necessary to ensure that the pressure difference between the front and rear of the feeder is preferably 0.05-3.0 MPa, and the liquid flow rate at the feed port is 5-40 m/s.

In the device for producing propylene oxide, preferably, the liquid-solid separator is a filter assembly, the filter assembly includes a shell and a filter tube, and the filter tube is selected from inorganic ceramic membranes, metal tubes One or a combination of membrane, metal mesh, and metal sintered tube.

In the device for producing propylene oxide, preferably, the liquid-solid separator shell is further provided with a catalyst feeding port.

In the device for producing propylene oxide, preferably, in the liquid-solid separator, a backwash pipeline is provided on the filter assembly.

In the device for producing propylene oxide, preferably, the outer circulation pipe is one or more, wherein the upper section of the outer circulation pipe is connected between the outlet of the reactor and the liquid-solid separator, Connecting between the liquid-solid separator retentate outlet and the tubular mixer is the lower section of the external circulation pipe;

Preferably, the inner diameter of the upper section of the outer circulation pipe and the lower section of the outer circulation pipe are the same.

Preferably, the ratio of the diameter of the external circulation pipe to the reactor is (0.3-3):1, preferably (0.5-2):1.

In the device for producing propylene oxide, preferably, the tubular mixer is a jet mixer, wherein the lower section of the circulation pipe is communicated with the main fluid inlet of the jet mixer, and the The water phase outlet of the liquid-liquid mixer communicates with the high-speed jet fluid inlet of the jet mixer.

The jet mixer has a main fluid inlet, a high-speed jet fluid inlet and an ejection outlet. During the reaction process, the high-speed jet fluid flow rate at the ejection outlet of the jet mixer is 3-30 m/s.

Preferably, the high-speed jet fluid inlet of the jet mixer is also connected to the continuous phase inlet, so as to supplement the reaction raw materials during the reaction process.

Preferably, the liquid-liquid separator is selected from one or a combination of conventional gravity settling tanks, oil-water coalescing separators and fiber membrane surface separators.

There are one or more external circulation pipes, one end of which is connected with the top of the reactor, and one end is connected with the bottom of the reactor to form a circulation loop. Preferably, the upper section of the outer circulation pipe and the lower section of the outer circulation pipe have the same inner diameter, and the ratio of the diameter of the outer circulation pipe to the straight pipe section of the reactor is (0.3-3):1, preferably (0.5-2):1.

Preferably, the liquid-solid separator is a filter assembly, which is used for liquid-solid separation of the material from the top of the reactor. The filter assembly includes a housing and a filter tube, and the filter tube is selected from one or a combination of inorganic ceramic membranes, metal tube membranes, metal screens, and metal sintered tubes. The filtering components can be one or more groups. The filter assembly is provided with a clear liquid outlet and a retentate liquid outlet, the clear liquid outlet is connected to the liquid-liquid separator, and the retentate liquid outlet is connected to the bottom of the reactor through the lower section of the downcomer. The mixer is returned to the bottom of the reactor.

The filter assembly is provided with an inlet for filtering the backwash liquid, and preferably, the inlet line of the backwash liquid and the outlet line of the clear liquid obtained by liquid-solid separation share an interface on the shell of the filter assembly. The backwash liquid is selected from filtered clear liquid, or fresh raw material liquid.

The lower section of the outer circulation pipe communicates with the jet mixer. The circulating material from the retentate outlet of the liquid-solid separator is used as the suction fluid of the jet mixer, the raw material from the continuous phase inlet and the circulating liquid phase from the water phase outlet of the liquid-liquid separator are used as high-speed jet fluid, and the jet flow rate It is preferably 3 to 30 m/s. The two materials are mixed by a jet mixer and then enter the bottom of the reactor.

In the method for producing propylene oxide provided by the present invention, the adopted granular oxidation catalyst is added to the reaction device through the catalyst feeding port arranged on the liquid-solid separator. Due to the inevitable wear and deactivation of a part of the catalyst during the reaction process, in order to ensure the overall activity of the catalyst, it is necessary to regularly inspect the activity and wear of the catalyst, and unload a part of the catalyst from the catalyst discharge port at the bottom of the riser reactor to achieve The online update of the catalyst avoids the shutdown of the device and affects the operation cycle of the device.

A system for producing propylene oxide, comprising a device for producing propylene oxide, a reaction system composed of water-oil two-phase reaction raw materials and oxidation catalyst particles, wherein the water phase is hydrogen peroxide and a solvent, the oil phase is propylene, and the oxidation The particle size of the catalyst particles is 0.05 to 3.0 mm, and the device for producing propylene oxide is composed of a riser reactor, a liquid-solid separator, a liquid-liquid separator and a tubular mixer, wherein the riser reactor The bottom is provided with a disperse phase inlet and a catalyst discharge outlet, the top of the reactor is connected to the inlet of the solid-liquid separator through an external circulation pipe, and the retentate outlet of the solid-liquid separator is connected to the bottom of the reactor through an external circulation pipe and a tubular mixer. , the clear liquid outlet of the solid-liquid separator is communicated with the inlet of the liquid-liquid separator, and the liquid-liquid separator is provided with a water phase outlet and an oil phase outlet, and the water phase outlet or the oil phase outlet It is communicated with the inlet of the tubular mixer; wherein, the water phase is used as the dispersed phase or the continuous phase. Hydrogen peroxide and solvent are preferred as the dispersed phase.

The method and system for producing propylene oxide of the present invention are further described below with reference to the accompanying drawings. However, the present invention is not limited thereby.

1 is a schematic flow diagram of a method for producing propylene oxide. As shown in Figure 1, the adopted reaction device for producing propylene oxide is composed of a reactor 5, a liquid-solid separator 8, a liquid-liquid separator 13 and a tubular mixer 4, wherein the bottom of the riser reactor is There is a disperse phase inlet 1 and a catalyst discharge outlet 6, the top of the reactor is communicated with the inlet of the solid-liquid separator 8 through the external circulation pipe 7, and the retentate outlet of the solid-liquid separator 8 is communicated with the bottom of the reactor through the tubular mixer 4 , the clear liquid outlet 10 of the solid-liquid separator is communicated with the inlet of the liquid-liquid separator 13, and the liquid-liquid separator 13 is provided with a water phase outlet 14 and an oil phase outlet 15. The outlet 14 communicates with the inlet of the tubular mixer 4 .

2 is a schematic flow diagram of the second embodiment of the method for producing propylene oxide. The difference from FIG. 1 is that the reactor is divided into a tube side I and a shell side II, and the tube side and the shell side are not connected. The upper and lower ends of the shell side are respectively provided with a heat exchange medium inlet 20 and a heat exchange medium outlet 21, wherein a reaction space is provided for the reaction material in the tube side, and the heat exchange medium and the reaction material in the tube side are introduced into the shell side to heat the reaction material. The exchange removes the heat of reaction to control the reaction temperature. The oil phase separated by the liquid-liquid separator 13 is returned to the bottom of the reactor 5 through the oil phase outlet 15 for circulating reaction, and the separated water phase enters the product separation system 16 through the water phase outlet 14 for further separation. In addition, the bottom of the reactor 5 is also provided with a continuous phase inlet 2 .

As shown in accompanying drawing 2, the method for producing propylene oxide provided by the present invention is described by taking hydrogen peroxide as the dispersed phase as an example, a certain amount of oxidation catalyst is pre-transferred in the riser reactor 5, and the catalyst is preferably titanium with MFI structure. Silicon molecular sieve, the particle diameter is 0.05～3.0mm. The fresh raw material propylene enters from the continuous phase inlet 2 as the continuous phase and fills the whole reactor, a certain amount of hydrogen peroxide (usually containing water) and the solvent, preferably methanol, are mixed in a certain proportion. 3 Entering the bottom of the reactor tube 5, in order to achieve a better dispersion effect and ensure a good circulation flow in the reactor, the pressure drop before and after the disperse phase feeder 3 is required to be 0.05-3.0MPa, and the initial outlet of the disperse phase feeder is required. The liquid flow rate reaches 5-40 m/s, and the diameter of the obtained dispersed phase droplets is less than 1 mm. In the reaction tube body I, titanium silicon molecular sieve catalyzes the oxidation of propylene with hydrogen peroxide to generate propylene oxide. The apparent liquid velocity in the reaction tube is controlled to exceed 20% to 120% of the critical sedimentation velocity of the catalyst particles or droplet particles (whichever is greater). A heat exchange medium is introduced into the reactor shell II to take out the heat of the reaction and control the temperature required for the reaction. Preferably, the flow of the cooling medium is opposite to the flow of the reaction material or the main body is cross-flow.

After the reaction, the material is extracted from the top of the reactor 5 and enters the external circulation pipe 7, and enters the liquid-solid separator 8 for liquid-solid separation. The liquid-solid separator 8 is a filter assembly, and the filter assembly includes a housing and a filter tube. The mixed material is cross-flow filtered on a filter assembly. When there are too many particles accumulated on the wall of the filter tube, optionally when the pressure difference between the two sides of the filter tube is greater than 0.2MPa, switch to the backwash stage, and use the backwash medium inlet 12 to introduce the backwash flow to the filter tube. The particles are backwashed, thereby restoring the permeability of the filter tube. Preferably, the backwash liquid inlet 12 and the filtered clear liquid outlet 10 can share a port. The backwash liquid is selected from filtered clear liquid, or fresh raw material liquid. The retentate of the liquid-solid separator 8 enters the jet jet mixer through the lower section of the outer circulation pipe as a circulating material, and enters the bottom of the riser reactor 5 after being mixed with the continuous phase feed. The circulating material is used as the suction fluid, and the continuous liquid phase feed is used as the high-speed jet fluid. In order to ensure a good mixing effect, the jet flow rate is preferably 3-30 m/s.

After the liquid-solid separator is filtered, the clear liquid enters the liquid-liquid separator 13 through the clear liquid outlet 10 . The liquid-liquid separator 13 is mainly used to separate the oil phase and the water phase, and can use a conventional gravity settling tank, a surface coalescing separator, a fiber membrane surface separator, a centrifugal separator, a cyclone separator or a variety of used in combination. The separated oil phase mainly composed of propylene returns to the reactor through the oil phase outlet 15 to participate in the reaction again, and the separated water phase rich in propylene oxide is extracted through the water phase outlet 14 and enters the subsequent product separation system 16 for For the separation of the target product, the product separation system 16 can be used in a variety of different unit operation modes such as conventional distillation separation, liquid-liquid extraction, adsorption separation, or a combination thereof.

The catalyst inlet 11 is preferably arranged on the liquid-solid separator 8, and the catalyst discharge outlet 6 is preferably arranged at the bottom of the reactor. Due to the inevitable wear and deactivation of a part of the catalyst during the reaction process, in order to ensure the overall activity of the catalyst, it is necessary to regularly inspect the activity and wear of the catalyst, and unload a part of the catalyst from the discharge port according to the situation, and replenish a part of fresh catalyst , to realize the online update of the catalyst, and avoid the shutdown of the device and affect the operation cycle of the device.

The application effects of the method and system for producing propylene oxide provided by the present invention are further described below through specific examples, but the present invention is not thereby limited.

In the examples and comparative examples, the purity of the raw material propylene is greater than 99.6%, and the titanium silicon molecular sieve catalyst brand HTS (Hunan Jianchang Company) is used. Hydrogen peroxide is commercially available, the concentration of hydrogen peroxide is 30 wt%, the concentration of remaining hydrogen peroxide is determined by KMnO ₄ titration, and the composition of the product is analyzed by gas chromatography.

Comparative Example 1

Comparative Example 1 A traditional fixed-bed reactor was used to oxidize propylene with hydrogen peroxide to produce propylene oxide, and the height-diameter ratio of the reactor was 20. The flow enters and exits up and down, and the reactor inlet is provided with a side-gap inlet distributor, and the flow in the reactor is naturally distributed.

The reaction inlet material is a mixture of propylene, hydrogen peroxide and solvent methanol, wherein the molar ratio of methanol to hydrogen peroxide is 40:1, the feed molar ratio of propylene to hydrogen peroxide is 2:1, the reaction inlet temperature is 35 ° C, the pressure is 1.6 MPa, and the reaction mass The apparent residence time in the reactor is 1.0h. The reactor outlet temperature was 78°C.

Sampling, analysis and calculation result of the reaction results in that the conversion rate of hydrogen peroxide is less than 90%, and the selectivity of propylene oxide is 82%.

Wherein, the hydrogen peroxide conversion rate is the ratio of the hydrogen peroxide consumed by the reaction to the amount of hydrogen peroxide added. Propylene oxide selectivity is the ratio of the amount of propylene oxide-producing species to the amount of hydrogen peroxide consumed.

Example 1

Example 1 illustrates the effect of the method for producing propylene oxide provided by the present invention.

Adopt the reaction device and flow process of producing propylene oxide as shown in accompanying drawing 2, the mixed solution that hydrogen peroxide and methanol are formed is used as disperse phase, wherein the mol ratio of methanol and hydrogen peroxide is 2.0, and the mol ratio of fresh propylene feed and hydrogen peroxide is 1.5 , the diameter of catalyst particles is 10-200 μm. The reactor contains 3 evenly distributed tubes, the bottom of each tube corresponds to a disperse phase feeder, the top of the disperse phase feeder is a 6mm sintered metal tube, the average pore diameter of the sintered tube is 7μm, and three disperse phase feeders It is connected with the disperse phase feed pipe through the loop pipe, and the total pressure drop of the feeder is 0.25MPa. A metal sintered tube filter assembly is set on the external circulation pipeline, with an average filter pore size of 6 μm. The liquid-solid mixture on the interception side of the filter assembly is circulated back to the reactor, the filtrate produced by the filter assembly enters the gravity settling tank for liquid-liquid separation, the upper oil phase obtained from the separation is returned to the reactor, and the lower water phase is extracted for product separation and analysis.

The inlet temperature of the reaction was 45°C, the outlet temperature of the reactor was controlled at 68°C by passing cooling water through the reactor shell, the pressure of the reaction part was 1.2MPa, and the apparent residence time of the reaction material in the reactor was 1.0h.

The conversion rate of hydrogen peroxide obtained by sampling analysis and calculation reaction results is greater than 96%, and the selectivity of propylene oxide is 95%.

Claims (13)

1. Propylene and hydrogen peroxide are mixed and contacted in a reactor in the presence of an oxidation catalyst for oxidation reaction, and the reacted material flow is separated to obtain propylene oxide; the device for producing the propylene oxide is characterized by comprising a riser reactor (5), a liquid-solid separator (8), a liquid-liquid separator (13) and a tubular mixer (4), wherein the bottom of the riser reactor is provided with a dispersed phase inlet (1) and a catalyst discharge outlet (6), the top of the reactor is communicated with the inlet of the solid-liquid separator through an external circulating pipe (7), a trapped liquid outlet of the solid-liquid separator is communicated with the bottom of the reactor through the external circulating pipe and the tubular mixer, a clear liquid outlet (10) of the solid-liquid separator is communicated with the inlet of the liquid-liquid separator, the liquid-liquid separator is provided with a water phase outlet and an oil phase outlet, and the water phase outlet or the oil phase outlet is communicated with the inlet of the tubular mixer (4);

preferably, the hydrogen peroxide in the reaction materials is used as a dispersed phase, and the propylene is used as a continuous phase.

2. The process for producing propylene oxide according to claim 1, wherein the oxidation catalyst is a titanium silicalite molecular sieve having an MFI structure, and the oxidation catalyst has a particle diameter of 0.05 to 3.0mm.

3. The process for producing propylene oxide according to claim 1 or 2, wherein the oxidation reaction conditions are: the pressure is 0.1-3.0 MPa, the temperature is 30-80 ℃, the reaction residence time is 0.3-3 h, and the molar ratio of the fresh feed propylene to the hydrogen peroxide is (1.0-3.0): 1, wherein a solvent is added or not added into the reaction materials, and the molar ratio of the solvent to the hydrogen peroxide is (0-10): 1;

the preferred solvent is methanol.

4. A process for producing propylene oxide according to any one of claims 1 to 3, wherein the riser reactor is divided into a tube side and a shell side, the upper and lower ends of the shell side are provided with a heat exchange medium inlet and a heat exchange medium outlet, respectively, wherein the tube side provides a reaction space for the reaction material, and the shell side is fed with a heat exchange medium to control the temperature.

5. A process for producing propylene oxide according to any one of claims 1 to 3, wherein the dispersed phase inlet (1) is provided with a dispersed phase feeder (3) which is a perforated pipe, a sintered metal pipe, an inorganic membrane pipe or an atomizing nozzle.

6. A process for producing propylene oxide according to claim 5, wherein the dispersed phase feeder 2 has a pressure drop before and after 0.05 to 3.0MPa and an initial liquid flow rate at the outlet of the dispersed phase feeder is 5 to 40m/s.

7. The method for producing propylene oxide according to any one of claims 1 to 3, wherein the liquid-solid separator is a filter module, the filter module comprises a shell and a filter tube, and the filter tube is one or a combination of inorganic ceramic membrane, metal tube membrane, metal screen and metal sintered tube.

8. A process for producing propylene oxide according to any one of claims 1 to 3, wherein said liquid-solid separator casing is further provided with a catalyst-feeding port.

9. The process for producing propylene oxide according to claim 8, wherein the liquid-solid separator is provided with a back-flushing line on the filter unit.

10. The process for producing propylene oxide according to claim 1, wherein the number of the external circulation pipes is one or more, wherein the upper section of the external circulation pipe is communicated between the outlet of the reactor and the liquid-solid separator, and the lower section of the external circulation pipe is communicated between the outlet of the liquid-solid separator and the tubular mixer;

preferably, the upper section of the external circulation pipe and the lower section of the external circulation pipe have the same inner diameter.

11. The process for producing propylene oxide according to claim 10, wherein the ratio of the diameter of the external circulation pipe to that of the reactor is (0.3 to 3): 1, preferably (0.5 to 2): 1.

12. a process for producing propylene oxide according to claim 1, wherein said tubular mixer is a jet mixer, wherein said lower section of said circulation pipe is in communication with a main fluid inlet of said jet mixer, and wherein an aqueous phase outlet of said liquid-liquid mixer is in communication with a high velocity jet fluid inlet of said jet mixer.

13. A system for producing propylene oxide is characterized by comprising a device for producing propylene oxide and a reaction system consisting of water phase and oil phase and oxidation catalyst particles, wherein the water phase is hydrogen peroxide and a solvent, the oil phase is propylene, the particle size of the oxidation catalyst particles is 0.05-3.0 mm, the device for producing propylene oxide consists of a riser reactor, a liquid-solid separator, a liquid-liquid separator and a tubular mixer, wherein the bottom of the riser reactor is provided with a dispersed phase inlet and a catalyst discharge outlet, the top of the reactor is communicated with the inlet of the solid-liquid separator through an external circulating pipe, the intercepted liquid outlet of the solid-liquid separator is communicated with the bottom of the reactor through an external circulating pipe and the tubular mixer, the clear liquid outlet of the solid-liquid separator is communicated with the inlet of the liquid-liquid separator, the liquid is provided with a water phase outlet and an oil phase outlet, and the water phase outlet or the oil phase outlet is communicated with the inlet of the tubular mixer.

Images