Gas distribution unit, bubbling bed reactor and reaction method

Abstract

The invention discloses a gas distribution unit, a bubbling bed reactor applying the same and a corresponding reaction method, and the gas distribution unit comprises a first gas distributor arranged below a catalyst bed layer and bubbling upwards; and the second gas distributor is arranged in the catalyst bed layer, and the second gas distributor bubbles downwards. According to the invention, through the gas distribution unit and the corresponding reactor, the gas phase feed distribution is more uniform, the conversion rate and selectivity of the reactor are effectively improved, and the catalyst deactivation phenomenon caused by too high local concentration of gas-liquid-solid three phases and violent reaction heat release is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of gas-liquid-solid catalytic reaction, and in particular to a gas distribution unit, a bubbling bed reactor using the unit, and a corresponding reaction method. Background Art

[0002] For gas-liquid-solid reactions using granular solid catalysts in bubbling reactors, how to increase the contact time and uniformity of bubbles in the liquid phase is a common concern in the industry. Taking the synthesis of ethylene carbonate in gas-liquid-solid reactions as an example, ethylene carbonate (EC) is a high-polarity solvent and fine chemical intermediate with excellent performance, and is a potential basic raw material for organic chemical industry. Electronic grade ethylene carbonate is an indispensable electrolyte solvent for power lithium batteries, and is also a synthetic raw material for high-end electrolyte additives such as vinylene carbonate and fluoroethylene carbonate. The main production methods of ethylene carbonate are phosgene method, ester exchange method, urea alcoholysis method and ethylene oxide and carbon dioxide addition method.

[0003] CO2 is a greenhouse gas. With the frequent occurrence of extreme weather in recent years, how to effectively fix CO2 has become an urgent issue that all mankind needs to solve. Driven by policies such as carbon peak and carbon neutrality, the synthesis of ethylene carbonate from ethylene oxide and CO2 is a good way that is both economical and social, and will have huge development potential in the future. The industrial production of EC mainly adopts homogeneous catalytic process, which has a simple reactor structure, but the subsequent separation process is complicated, the cost is high, and there are many three wastes. The advantage of heterogeneous catalytic technology is that the reaction product does not contain a catalyst, which simplifies the separation process of the reaction product due to the use of homogeneous catalysts, and reduces the emission of three wastes.

[0004] Chinese patent application CN106475017A discloses a gas-liquid-solid three-phase reactor for synthesizing ethylene carbonate from ethylene oxide and carbon dioxide, which includes a liquid discharge port, a liquid baffle, a gas feed port, a gas inlet distributor, a catalyst lower support sieve plate, a lower porcelain ball layer, a catalyst layer, an upper porcelain ball layer, a catalyst upper support sieve plate, a liquid feed port, a liquid feed distributor and a gas discharge port from bottom to top. The gas and liquid feeds enter the catalyst bed layer radially and uniformly through the gas distributor and the liquid distributor, respectively. The catalyst bed layer is fixed in the reactor by upper and lower porcelain balls and upper and lower support sieve plates. Multiple groups of baffles are arranged at the bottom of the reactor, and overflow weirs are arranged on both sides. Although this scheme can achieve better separation of gas and liquid through the overflow weir, it increases the liquid flow resistance, and the gas operation flux is small, which limits the production capacity of the reactor. The gas in the bed cannot be evenly distributed, which reduces the reactor conversion rate and selectivity, and it is easy to have excessive concentration of the gas-liquid-solid three-phase local concentration and intense reaction exotherm, resulting in catalyst deactivation.

[0005] Therefore, there is an urgent need for a gas distribution unit and a bubbling bed reactor suitable for gas-liquid-solid reactions, which can evenly distribute the gas to improve the reactor conversion rate and selectivity and effectively avoid catalyst deactivation.

[0006] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention and should not be regarded as an acknowledgment or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the invention

[0007] The object of the present invention is to provide a gas distribution unit, a bubbling bed reactor and a corresponding reaction method. The gas distribution unit can make the gas phase feed distribution more uniform, effectively improve the conversion rate and selectivity of the reactor, and avoid the occurrence of excessive local concentration of gas-liquid-solid three-phases and intense reaction exotherm, thereby avoiding catalyst deactivation.

[0008] To achieve the above-mentioned purpose, according to the first aspect of the present invention, the present invention provides a gas distribution unit, which is applied to a gas-liquid-solid three-phase bubbling bed reactor, comprising: a first gas distributor, which is arranged below the catalyst bed and bubbles upward; a second gas distributor, which is arranged inside the catalyst bed and bubbles downward.

[0009] Furthermore, in the above technical solution, a granular solid catalyst is arranged in the catalyst bed and is confined within the bed.

[0010] Furthermore, in the above technical solution, the second gas distributor can be arranged in 1 to 4 layers at different heights in the catalyst bed, preferably 2 layers.

[0011] Furthermore, in the above technical solution, first air holes for bubbling upwards may be uniformly formed on the first gas distributor; and second air holes for bubbling downwards may be uniformly formed on the second gas distributor.

[0012] Furthermore, in the above technical solution, the second air holes can be arranged in two or more rows; when there are two rows of second air holes, the two rows of air holes are symmetrical and inclined downward, and the angle α between the air hole direction and the vertical direction ranges from 25° to 65°.

[0013] Furthermore, in the above technical solution, when the second gas distributor is provided in two layers, the angle α of the second pores in the upper layer may be greater than or equal to the angle α of the second pores in the lower layer. The difference between the angles α of the upper and lower layers may be 5°-25°.

[0014] Furthermore, in the above technical solution, when two or more layers of the second gas distributors are provided, the second gas distributors of adjacent layers have an overall inclination angle δ in the horizontal direction, and the angle range of δ may be 0°-135°.

[0015] Furthermore, in the above technical solution, the installation height of the second gas distributor at the uppermost layer may be less than or equal to 80% of the height of the catalyst bed.

[0016] Furthermore, in the above technical solution, the first air holes can be arranged in two or more rows; when there are two rows of first air holes, the two air holes can be arranged symmetrically and tilted upward, and the angle β between the air hole direction and the vertical direction can range from 30° to 60°.

[0017] Furthermore, in the above technical solution, the first gas distributor and the second gas distributor may be composed of a main pipe and multiple branch pipes perpendicular to each other, and the coverage of the branch pipes is adapted to the cross-section of the bubbling bed reactor; the opening rate of the main pipe and the branch pipe is 1‰-45‰.

[0018] According to a second aspect of the present invention, the present invention provides a bubbling bed reactor, which is applied to any one of the aforementioned gas distribution units.

[0019] Furthermore, in the above technical solution, the reactor further comprises: a liquid distributor, which is arranged above the catalyst bed and is used to provide a liquid phase feed for the reaction; the liquid phase feed immerses the solid catalyst bed. The opening rate of the liquid distributor can be 1‰-65‰.

[0020] Furthermore, in the above technical solution, the reactor may also include: a catalyst bed, which is one layer or multiple layers. When the catalyst bed is multiple layers, the gas distribution unit may be independently arranged in each bed.

[0021] Furthermore, in the above technical solution, supporting sieve plates may be provided at the upper end and the lower end of the catalyst bed, respectively.

[0022] Furthermore, in the above technical solution, the outer wall of the bubbling bed reactor can be wrapped with a cooling jacket according to specific reaction conditions.

[0023] According to the third aspect of the present invention, there is provided a reaction method, using any one of the aforementioned bubbling bed reactors, comprising: liquid feed enters the reactor through a liquid distributor and establishes a liquid level that submerges the catalyst bed; gas feed passes through a first gas distributor and a second gas distributor to form a counter-spray, and bubbles from the second gas distributor return in the liquid phase at the catalyst bed; under the combined action of the returning bubbles and the rising bubbles from the first gas distributor, the solid catalyst particles are in a tumbling motion state in the bed.

[0024] Furthermore, in the above technical solution, the reaction method can be used to synthesize ethylene carbonate. The liquid feed in the reaction can be ethylene oxide, and the gas feed can be carbon dioxide.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1) In the present invention, the gas entering the reactor through the second gas distributor has an initial downward velocity. Under the buoyancy of the liquid phase feed, the bubbles generated by the second gas distributor located in the catalyst bed are turned back and forth, so that the bubbles stay in the catalyst bed for a longer time, which promotes gas-liquid mass transfer. In addition, since the bubbles generated by the first gas distributor always run from bottom to top, the bubbles with different running trajectories increase the turbulence of the liquid phase. Under the turbulence of the liquid phase, the catalyst particles are always in a tumbling motion state during the entire reaction process, so that the gas-liquid-solid reaction is more sufficient.

[0027] 2) The present invention can arrange only one layer of the second gas distributor in the catalyst bed, or two or more layers; when multiple layers are arranged, the installation height of the second gas distributor of the uppermost layer is less than or equal to 80% of the height of the catalyst bed, preferably two layers can effectively save the space of the reactor, and the design of the installation height can leave enough running space for the bubble return;

[0028] 3) The second pore arrangement of the present invention is inclined downward so that the gas entering the reactor has an initial velocity that is inclined downward, and the velocity has a downward component in the vertical direction and a horizontal outward component, which can ensure that the gas in the lower area of ​​the second gas distributor is evenly dispersed, and the excess gas that has not reacted in time will change its movement direction after a period of time due to the effect of buoyancy and become upward movement, and at the same time, the bubble coverage area is wider, ensuring that the gas in the upper area of ​​the distributor can also be evenly distributed;

[0029] 4) When two layers of the second gas distributor are provided, the present invention can make the downward velocity component of the gas entering the reactor through the upper second gas distributor smaller by making the inclination angle of the pores of the upper second gas distributor (i.e., the angle α) greater than the corresponding inclination angle of the lower layer, thereby ensuring that more gas eventually moves upward due to buoyancy, further ensuring that the gas is evenly distributed in the reactor, and improving the conversion rate and selectivity of the reactor;

[0030] 5) When two or more layers of the second gas distributor are arranged, the second gas distributors of adjacent layers are arranged as a whole to have an inclination angle δ in the horizontal direction to form a staggered arrangement of the second gas distributors of different layers, which can further increase the degree of gas-liquid turbulence, promote mixing, and improve the conversion rate and selectivity of the reaction;

[0031] 6) The catalyst bed of the bubbling bed reactor of the present invention preferably adopts one layer; when the catalyst bed is more than one layer, a first gas distributor needs to be installed in the space between the beds, and at least one second gas distributor is installed in each bed, that is, the reactor is divided into two relatively independent reaction beds, and each gas distributor is configured respectively, which can reduce the degree of system back mixing, improve the reaction rate and conversion rate, but the temperature control and feed need to be adjusted accordingly to avoid the reactor temperature runaway phenomenon;

[0032] 7) The conversion rate and selectivity data of the reaction in the embodiments of the present invention are all data of a single reactor, which has obvious technical effects compared with the single reactor in the prior art (in the prior art, two or more reactors are usually required to ensure a certain optimization effect).

[0033] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, and to make the above and other purposes, technical features and advantages of the present invention easier to understand, one or more preferred embodiments are listed below and described in detail with the accompanying drawings as follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a schematic structural diagram of the bubbling bed reactor of the present invention.

[0035] Figure 2 It is a structural schematic diagram of the first gas distributor in the gas distribution unit of the present invention.

[0036] Figure 3 It is a schematic diagram of the structure of the second gas distributor in the gas distribution unit of the present invention.

[0037] Figure 4 It is a schematic cross-sectional view of the branch pipe of the first gas distributor of the present invention (showing the gas holes arranged inclined upward).

[0038] Figure 5 It is a schematic cross-sectional view of the branch pipe of the second gas distributor of the present invention (showing the gas holes arranged at a downward inclination).

[0039] Description of main reference numerals:

[0040] 1-bubbling bed reactor, 11-catalyst layer, 12A-first gas distributor, 12B / 12C-second gas distributor, 120-air hole, 121-gas distribution main pipe, 122-gas distribution branch pipe, 13-liquid distributor, 14-catalyst supporting sieve plate, 15-cooling jacket, 16-gas outlet, 17-liquid outlet. DETAILED DESCRIPTION

[0041] The specific implementation modes of the present invention are described in detail below in conjunction with the accompanying drawings, but it should be understood that the protection scope of the present invention is not limited by the specific implementation modes.

[0042] Unless explicitly stated otherwise, throughout the specification and claims, the term “comprise” or variations such as “include” or “comprising”, etc., will be understood to include the stated elements or components but not to exclude other elements or components.

[0043] In this document, for the convenience of description, spatial relative terms such as "below", "below", "down", "above", "above", "upper", etc. may be used to describe the relationship between one element or feature and another element or feature in the accompanying drawings. It should be understood that the spatial relative terms are intended to include different orientations of the object in use or operation in addition to the orientation depicted in the figure. For example, if the object in the figure is turned over, the element described as being "below" or "below" other elements or features will be oriented "above" the element or feature. Therefore, the exemplary term "below" can include both below and above. Objects may also have other orientations (rotated 90 degrees or other orientations) and the spatial relative terms used in this document should be interpreted accordingly.

[0044] In this document, the terms "first", "second", etc. are used to distinguish two different elements or parts, and are not used to limit a specific position or relative relationship. In other words, in some embodiments, the terms "first", "second", etc. can also be interchangeable.

[0045] The gas distribution unit of the present invention and the bubbling bed reactor using the unit are suitable for gas-liquid-solid reactions using a bubbling bed reactor. The present invention is described by taking the gas-liquid-solid catalytic reaction process of synthesizing ethylene carbonate as an example. In view of the problem that the uneven distribution of the gas phase in the reactor in the prior art reduces the conversion rate and selectivity of the reactor, and the problem that the local concentration of the gas is too high, resulting in intense heat release of the reaction and deactivation of the catalyst, the present invention effectively overcomes the difficulty of reactor design for the above-mentioned problems. The inventor has found through research that the uniform distribution of gas in the gas-liquid-solid three-phase reactor has always been a difficulty in reactor design. If the gas cannot be evenly distributed, it will inevitably lead to a decrease in reaction conversion rate and selectivity. When the local concentration of the gas in the reactor is too high, it is more likely to cause excessive heat release of the reaction, and the heat will not be removed in time, so that the catalyst is deactivated due to high temperature. More seriously, thermal runaway will occur, affecting the intrinsic safety of the reaction. The gas distribution unit provided by the present invention and the bubbling bed reactor for heterogeneous catalytic synthesis of ethylene carbonate using the unit have the advantages of uniform gas phase feed distribution, high reaction conversion rate and selectivity, large operating load, easier control of reactor temperature, etc. during the synthesis of ethylene carbonate, and are suitable for industrial large-scale production of high-purity electronic grade ethylene carbonate.

[0046] like Figure 1 As shown, the present invention provides a bubbling bed reactor 1 for synthesizing ethylene carbonate, which is a columnar tank structure. Based on the fact that the reaction of the present invention is an exothermic reaction, a cooling jacket 15 is wrapped around the outer wall of the bubbling bed reactor 1 to allow a cooling medium to be introduced into the jacket to remove heat. The bubbling bed reactor 1 includes a solid catalyst bed 11, a gas distribution unit 12, and a liquid distributor 13. The catalyst bed 11 can be set as one or more layers. When the catalyst bed is multi-layered, the gas distribution unit 12 is independently set in each bed. The present invention preferably uses a catalyst bed 11. When the catalyst bed is more than one layer, a first gas distributor 12A needs to be installed in the space between the beds, and at least one second gas distributor 12B / 12C is installed in each bed. The advantage of a two-layer bed is that the reaction system is a fully mixed flow system, and the gas-liquid-solid three-phase back-mixing is serious. Dividing the reactor into two relatively independent reaction beds and configuring respective gas distributors can reduce the degree of system back-mixing and improve the reaction rate and conversion rate, but the temperature control and feed need to be adjusted accordingly to avoid the reactor temperature runaway phenomenon. The upper and lower ends of the catalyst bed 11 are respectively provided with supporting sieve plates 14. Since the solid catalyst used in the present invention is granular and immersed in the liquid phase feed, the particles are in a tumbling motion state during the reaction process. Therefore, the supporting sieve plates 14 at the upper and lower ends can limit the granular solid catalyst to the catalyst bed of this layer. The liquid distributor 13 is arranged above the catalyst bed to provide liquid phase feed ethylene oxide for synthesizing ethylene carbonate, and the liquid phase feed immerses the solid catalyst bed. Specifically, the liquid distributor 13 is a combination of a main pipe and a branch pipe, and at least one row of small holes facing downward is opened on the main pipe and the branch pipe. When there are more than one row of holes, the opening direction can be symmetrically distributed along the lowest point of the lower part of the pipe. Preferably, two to five rows of small holes are opened, and the porosity is 1‰-95‰, and the porosity is preferably 1‰-65‰.

[0047] Further Figure 1 As shown, the gas distribution unit 12 for synthesizing ethylene carbonate of the present invention is applied to a gas-liquid-solid three-phase bubbling bed reactor to provide carbon dioxide gas required for the reaction, and the gas distribution unit 12 comprises: a first gas distributor 12A and a second gas distributor 12B / 12C. Preferably, but not restrictively, the first gas distributor and the second gas distributor are each composed of a main pipe 121 and a plurality of branch pipes 122 perpendicular to each other, and the coverage of the branch pipe 122 is adapted to the cross section of the bubbling bed reactor (refer to Figure 2 and Figure 3 ); the opening rate of the main pipe and the branch pipe is 1‰-45‰. Among them, the first gas distributor 12A is arranged below each catalyst bed layer, and the first gas holes for bubbling upward are uniformly provided on the first gas distributor 12A (refer to Figure 4The second gas distributor 12B / 12C is arranged inside each catalyst bed layer, and the second gas distributor is evenly provided with second gas holes for bubbling downward (refer to Figure 5 The gas hole 120 in the reactor is formed by the second gas hole, and the bubbles formed by the second gas hole are first sprayed downward and then return to rise in the liquid phase of ethylene oxide. The present invention utilizes the viscosity of the liquid phase feed ethylene oxide at a certain reaction temperature, and the carbon dioxide gas entering the reactor through the second gas distributor 12B / 12C has an initial downward velocity. Under the buoyancy of the liquid phase feed, the excessive gas that has not reacted in time will change its movement direction after a period of time and become an upward movement. That is, the bubbles generated by the second gas distributor located in the catalyst bed layer are returned to run, so that the bubbles stay in the catalyst bed layer for a longer time, which promotes the mass transfer of gas and liquid. In addition, since the bubbles generated by the first gas distributor 12A always run from bottom to top, the bubbles with different running trajectories increase the turbulence of the liquid phase. Under the turbulence of the liquid phase, the catalyst particles are always in a tumbling motion state during the entire reaction process, so that the gas-liquid-solid reaction is more sufficient.

[0048] Further Figure 1 As shown, the second gas distributor 12B / 12C can be arranged in one to four layers at different heights in the catalyst bed. Considering the space limitation of the reactor and leaving enough running space for the bubble return, the present invention preferably adopts two layers of the second gas distributor, i.e. Figure 1 The second gas distributor 12B and the second gas distributor 12C. It should be noted here that only one layer of the second gas distributor is arranged in the catalyst bed, and the purpose of the present invention can also be achieved; when multiple layers are arranged, the installation height of the second gas distributor in the uppermost layer is less than or equal to 80% of the height of the catalyst bed. Second air holes are provided on the main pipe and branch pipe of the second gas distributor. The second air holes are arranged in two or more rows, preferably two to five rows, with an opening rate of 1‰-60‰, and a preferred opening rate of 1‰-45‰. When there are two rows of second air holes, the two air holes are symmetrical and inclined downward (reference Figure 5 , when there are more than two rows, the opening direction is symmetrically distributed along the lowest point of the lower part of the tube), and the angle α between the direction of the air hole and the vertical direction ranges from 25° to 65°. The second air hole arrangement inclined downward makes the carbon dioxide gas entering the reactor have an initial velocity inclined downward, and the velocity has a downward component in the vertical direction and a horizontal outward component, which can ensure that the gas in the lower area of ​​the gas distributor is evenly dispersed, and the excess gas that has not reacted in time will change its movement direction after a period of time due to the effect of buoyancy and become upward movement, and at the same time make the bubble cover a wider area, thereby ensuring that the gas in the upper area of ​​the distributor is also evenly distributed.

[0049] Further, when the second gas distributor is provided with two layers, that is, Figure 1In the lower second gas distributor 12B and the upper second gas distributor 12C, the angle α of the second pores of the upper 12C is greater than or equal to the angle α of the second pores of the lower 12B. Preferably, but not restrictively, the difference between the angles α of the upper and lower layers is 5°-25°. With such a setting, the gas in the lower area of ​​the upper layer 12C is more than the gas in the lower area of ​​the lower layer 12B, and the opening angle α of the upper layer 12C is larger, which can make the downward velocity component of the gas entering the reactor through the upper second gas distributor 12C smaller, and can ensure that more gas will eventually move upward due to buoyancy. This method can further ensure that the carbon dioxide gas is evenly distributed in the reactor, and improve the conversion rate and selectivity of the reactor.

[0050] Further Figures 1 to 3 As shown, when two or more layers of the second gas distributor are provided, the second gas distributors of adjacent layers have an inclination angle δ in the horizontal direction as a whole, and the angle range of δ is 0°-135°. Figure 2 The first gas distributor 12A shown in the figure is a reference (the main pipe 121 of the first gas distributor is arranged horizontally, and each branch pipe 122 is arranged vertically to the main pipe), the lower second gas distributor 12B can be arranged in the same manner as the first gas distributor 12A, and the upper second gas distributor 12C can be rotated counterclockwise by an angle δ in the horizontal direction as a whole. If there are more than two layers of second gas distributors, the staggered arrangement of second gas distributors of different layers is formed by analogy. The second gas distributor adopts such a staggered arrangement, which can further increase the degree of gas-liquid turbulence, promote mixing, and improve the conversion rate and selectivity of the reaction.

[0051] Further Figure 2 , 4 As shown, the opening of the first gas distributor 12A at the bottom of the reactor is upward. When the opening is in a row, the opening is located at the highest position of the gas distribution main pipe 121 and the gas distribution branch pipe 122. The present invention preferably uses two rows of symmetrically distributed and inclined upward gas holes 120, and the opening forms a certain angle β with the vertical direction, and the value range of β is 0°-90°, preferably 30°-60°. The opening direction of the first gas distributor 12A makes the gas entering the reactor have an initial velocity that is obliquely upward, and the velocity has an upward component in the vertical direction. This method can maximize the uniform distribution of the gas phase in the reactor and improve the conversion rate and selectivity of the reactor.

[0052] like Figure 1 As shown, the process flow of the bubbling bed reactor for the heterogeneous catalytic synthesis of ethylene carbonate of the present invention is as follows:

[0053] Liquid ethylene oxide enters the reactor 1 from the liquid distributor 13, and establishes a liquid level in the reactor to achieve the immersion of the catalyst bed by the liquid phase. The gas phase CO2 enters the reactor 1 from the first gas distributor 12A and the second gas distributor 12B / 12C in a bubbling state. Since the pore opening direction of the first gas distributor 12A is inclined upward, CO2 flows through the lower catalyst support screen plate 14 at an initial velocity inclined upward and enters the catalyst bed 11 for reaction. Since the pore opening direction of the second gas distributor 12B and 12C is inclined downward, CO2 enters the catalyst bed 11 at an initial velocity inclined downward for reaction. When the gas velocity drops to zero due to resistance, it begins to move back and forth upward due to buoyancy, which can fully ensure that the CO2 gas in the area between the catalyst support screen plate 14 and the second gas distributor 12B and the area between the second gas distributor 12B and the second gas distributor 12C is fully and evenly distributed, thereby improving the reaction conversion rate and selectivity. Liquid ethylene oxide and gaseous CO2 undergo a gas-liquid-solid three-phase catalytic reaction in the catalyst bed 11 to produce ethylene carbonate. The product flows out of the reactor 1 through the liquid outlet 17 in the form of a liquid phase, and the unreacted CO2 is discharged from the gas outlet 16 at the top of the reactor 1.

[0054] Example 1

[0055] The reactor has a diameter of 1600 mm and a catalyst bed is provided in one layer. The first and second gas distributors are composed of a gas distribution main pipe 121 and five gas distribution branch pipes 122, and the main pipe and the branch pipes are perpendicular. The second gas distributor 12C is rotated counterclockwise by an angle δ relative to the first gas distributor 12A, δ = 0°. The second gas distributors 12B and 12C are provided with two rows of symmetrically distributed and downwardly inclined gas holes, and the openings are at a certain angle α to the vertical direction, and α 12B =α 12C =45°. The first gas distributor 12A has two rows of symmetrically distributed and upwardly inclined pores, and the openings form a certain angle β with the vertical direction, β=30°. The second gas distributor 12B is installed at 25% of the height of the catalyst bed 11, and the second gas distributor 12C is installed at 50% of the height of the catalyst bed 11. The porosity of all gas distributors is 25‰, and the porosity of the liquid distributor 13 is 45‰. Ethylene oxide and carbon dioxide are reacted in the above-mentioned reactor to synthesize ethylene carbonate. The catalyst uses a commercial solid catalyst. The conversion rate of a single reactor is 87.1%, and the selectivity is 96.5%.

[0056] Example 2

[0057] The reactor has a diameter of 1600 mm and a catalyst bed is provided in one layer. The first and second gas distributors are composed of a gas distribution main pipe 121 and five gas distribution branch pipes 122, and the main pipe and the branch pipe are perpendicular. The second gas distributor 12C is rotated counterclockwise by an angle δ relative to the first gas distributor 12A, δ = 30°. The second gas distributors 12B and 12C are provided with two rows of symmetrically distributed and downwardly inclined gas holes, and the openings are at a certain angle α to the vertical direction, and α 12B =45°, α 12C =55°. The first gas distributor 12A has two rows of symmetrically distributed pores inclined upward, and the openings form a certain angle β with the vertical direction, β=45°. The second gas distributor 12B is installed at 25% of the height of the catalyst bed 11, and the second gas distributor 12C is installed at 50% of the height of the catalyst bed 11. The porosity of all gas distributors is 25‰, and the porosity of the liquid distributor 13 is 45‰. Ethylene oxide and carbon dioxide are reacted in the above-mentioned reactor to synthesize ethylene carbonate. The catalyst uses the same commercial solid catalyst as in Example 1. The conversion rate of a single reactor is 94.2%, and the selectivity is greater than 99.9%.

[0058] [Comparative Example 1]

[0059] The reactor structure is designed according to Example 2. The reactor of Example 2 adopts a reaction temperature of 100°C, while the comparative example 1 adopts a reaction temperature of 110°C. Ethylene oxide and carbon dioxide are reacted in the above reactor to synthesize ethylene carbonate. The catalyst adopts the same solid catalyst. The conversion rate of a single reactor is 93.1% and the selectivity is 99.0%. It can be seen that for the reaction of the present invention, the increase in temperature will bring about a change in the viscosity of the liquid phase. When the reaction temperature of the comparative example 1 increases, the corresponding conversion rate and selectivity will decrease.

[0060] [Comparative Example 2]

[0061] The reactor has a diameter of 1600 mm, and a catalyst bed is provided with one layer. The first and second gas distributors are composed of a gas distribution main pipe 121 and five gas distribution branch pipes 122, and the main pipe and the branch pipe are vertical. In Comparative Example 2, only one first gas distributor 12A is provided, on which two rows of symmetrically distributed and upwardly inclined pores are provided, and the openings form a certain angle β with the vertical direction, β=45°, and no second gas distributor is provided inside the catalyst bed. The porosity of the first gas distributor 12A is 25‰, and the porosity of the liquid distributor 13 is 45‰. Ethylene oxide and carbon dioxide are reacted to synthesize ethylene carbonate in the above-mentioned reactor, and the catalyst uses the same solid catalyst. The conversion rate of a single reactor is 78.8%, and the selectivity is 91.1%.

[0062] [Comparative Example 3]

[0063] The reactor has a diameter of 1600 mm and a catalyst bed is provided in one layer. The first and second gas distributors are composed of a gas distribution main pipe 121 and five gas distribution branch pipes 122, and the main pipe and the branch pipes are vertical. The second gas distributor 12B has two rows of symmetrically distributed and downwardly inclined gas holes, and the openings form a certain angle α with the vertical direction, and α 12B =45°. The second gas distributor 12B is installed at 25% of the height of the catalyst bed 11. The reactor has only one second gas distributor 12B in the bed. The opening rate of the second gas distributor 12B is 25‰, and the opening rate of the liquid distributor 13 is 45‰. Ethylene oxide and carbon dioxide are reacted in the above reactor to synthesize ethylene carbonate. The catalyst uses the same solid catalyst. The conversion rate of a single reactor is 80.1% and the selectivity is 92.8%.

[0064] Example 3

[0065] The reactor has a diameter of 1600 mm and a catalyst bed is provided in one layer. The first and second gas distributors are composed of a gas distribution main pipe 121 and five gas distribution branch pipes 122, and the main pipe and the branch pipe are perpendicular. The second gas distributor 12C is rotated counterclockwise by an angle δ relative to the first gas distributor 12A, δ = 30°. The second gas distributors 12B and 12C are provided with two rows of symmetrically distributed and downwardly inclined gas holes, and the openings are at a certain angle α to the vertical direction, and α 12B =60°, α 12C =30°. The first gas distributor 12A has two rows of symmetrically distributed and upwardly inclined holes, and the holes form a certain angle β with the vertical direction, β=45°. The second gas distributor 12B is installed at 25% of the height of the catalyst bed 11, and the second gas distributor 12C is installed at 50% of the height of the catalyst bed 11. The porosity of all gas distributors is 25‰, and the porosity of the liquid distributor 13 is 45‰. Ethylene oxide and carbon dioxide are reacted in the above-mentioned reactor to synthesize ethylene carbonate. The catalyst uses the same solid catalyst. The conversion rate of a single reactor is 88.4%, and the selectivity is 97.6%.

[0066] Example 4

[0067] The reactor has a diameter of 1600 mm and a catalyst bed is provided in one layer. The first and second gas distributors are composed of a gas distribution main pipe 121 and five gas distribution branch pipes 122, and the main pipe and the branch pipes are perpendicular. The second gas distributor 12C is rotated counterclockwise by an angle δ relative to the first gas distributor 12A, δ = 45°. The second gas distributors 12B and 12C are provided with two rows of symmetrically distributed and downwardly inclined gas holes, and the openings are at a certain angle α to the vertical direction, and α 12B =60°, α 12C=70°. The first gas distributor 12A has two rows of symmetrically distributed and upwardly inclined holes, and the holes form a certain angle β with the vertical direction, β=45°. The second gas distributor 12B is installed at 30% of the height of the catalyst bed 11, and the second gas distributor 12C is installed at 60% of the height of the catalyst bed 11. The porosity of all gas distributors is 15‰, and the porosity of the liquid distributor 13 is 40‰. Ethylene oxide and carbon dioxide are reacted in the above-mentioned reactor to synthesize ethylene carbonate. The catalyst uses the same solid catalyst. The conversion rate of a single reactor is 90.8%, and the selectivity is 98.6%.

[0068] Example 5

[0069] The reactor has a diameter of 1200 mm and a catalyst bed is provided in one layer. The first and second gas distributors are composed of a gas distribution main pipe 121 and five gas distribution branch pipes 122, and the main pipe and the branch pipes are perpendicular. The second gas distributor 12C is rotated counterclockwise by an angle δ relative to the first gas distributor 12A, δ = 30°. The second gas distributors 12B and 12C are provided with two rows of symmetrically distributed and downwardly inclined gas holes, and the openings are at a certain angle α to the vertical direction, and α 12B =45°, α 12C =55°. The first gas distributor 12A has two rows of symmetrically distributed and upwardly inclined holes, and the holes form a certain angle β with the vertical direction, β=45°. The second gas distributor 12B is installed at 25% of the height of the catalyst bed 11, and the second gas distributor 12C is installed at 50% of the height of the catalyst bed 11. The porosity of all gas distributors is 8‰, and the porosity of the liquid distributor 13 is 15‰. Ethylene oxide and carbon dioxide are reacted in the above-mentioned reactor to synthesize ethylene carbonate. The catalyst uses the same solid catalyst. The conversion rate of a single reactor is 90.1% and the selectivity is 98.2%.

[0070] Example 6

[0071] The reactor has a diameter of 1600 mm and two layers of catalyst beds are provided. The first and second gas distributors are each composed of a gas distribution main pipe 121 and five gas distribution branch pipes 122, and the main pipe and the branch pipe are vertical. In this embodiment, a first gas distributor 12A and a second gas distributor 12B are respectively provided at corresponding positions of the two beds. The opening angle α of the second gas distributor 12B in the bed is 45°. The opening angle β of the first gas distributor 12A at the bottom of the bed is 45°. The installation positions of the two second gas distributors 12B are 25% of the height of the corresponding catalyst bed 11. The opening rate of all gas distributors is 25‰, and the opening rate of the liquid distributor 13 is 45‰. Ethylene oxide and carbon dioxide are reacted to synthesize ethylene carbonate in the above-mentioned reactor, and the catalyst adopts the same solid catalyst. The conversion rate of a single reactor is 94.8%, and the selectivity is greater than 99.9%.

[0072] The foregoing description of specific exemplary embodiments of the present invention is for the purpose of illustration and demonstration. These descriptions are not intended to limit the present invention to the precise form disclosed, and it is clear that many changes and variations can be made based on the above teachings. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the present invention and its practical application, so that those skilled in the art can realize and utilize various different exemplary embodiments of the present invention and various different selections and changes. Any simple modifications, equivalent changes and modifications made to the above exemplary embodiments should fall within the scope of protection of the present invention.

Claims

1. A gas distribution unit, characterized in that: Applied in gas-liquid-solid three-phase bubbling bed reactor, including: A first gas distributor, which is disposed below the catalyst bed and bubbles upward; A second gas distributor is disposed inside the catalyst bed and bubbles downward.

2. The gas distribution unit according to claim 1, characterized in that The catalyst bed is provided with a granular solid catalyst which is confined within the bed.

3. The gas distribution unit according to claim 1, characterized in that The second gas distributor is arranged in 1 to 4 layers at different heights in the catalyst bed, preferably in 2 layers.

4. The gas distribution unit according to claim 1, characterized in that The first gas distributor is evenly provided with first gas holes for bubbling upward; the second gas distributor is evenly provided with second gas holes for bubbling downward.

5. The gas distribution unit according to claim 4, characterized in that The second air holes are arranged in two or more rows; when there are two rows of second air holes, the two rows of air holes are symmetrical and inclined downward, and the angle α between the air hole direction and the vertical direction ranges from 25° to 65°.

6. The gas distribution unit according to claim 5, characterized in that When two layers of the second gas distributor are provided, the angle α of the second pores in the upper layer is greater than or equal to the angle α of the second pores in the lower layer.

7. The gas distribution unit according to claim 6, characterized in that The difference between the angle α between the upper and lower layers is 5°-25°.

8. The gas distribution unit according to claim 3, characterized in that When two or more layers of the second gas distributors are provided, the second gas distributors in adjacent layers have an inclination angle δ in the horizontal direction as a whole, and the angle range of δ is 0°-135°.

9. The gas distribution unit according to claim 3, characterized in that The installation height of the second gas distributor at the uppermost layer is less than or equal to 80% of the height of the catalyst bed.

10. The gas distribution unit according to claim 1, characterized in that The first air holes are arranged in two or more rows; when there are two rows of first air holes, the two air holes are arranged symmetrically and tilted upward, and the angle β between the air hole direction and the vertical direction ranges from 30° to 60°.

11. The gas distribution unit according to claim 1, characterized in that The first gas distributor and the second gas distributor are composed of a main pipe and a plurality of branch pipes which are perpendicular to each other, and the coverage of the branch pipes is adapted to the cross section of the bubbling bed reactor; the opening ratio of the main pipe and the branch pipe is 1‰-45‰.

12. A bubbling bed reactor, characterized in that: Applicable to the gas distribution unit as claimed in any one of claims 1 to 11.

13. The bubbling bed reactor according to claim 12, characterized in that: Also includes: A liquid distributor, which is arranged above the catalyst bed and is used to provide a liquid phase feed for the reaction; The liquid feed submerges the solid catalyst bed.

14. The bubbling bed reactor according to claim 13, characterized in that: The opening rate of the liquid distributor is 1‰-65‰.

15. The bubbling bed reactor according to claim 12, characterized in that: Also includes: The catalyst bed is one layer or multiple layers. When the catalyst bed is multiple layers, the gas distribution unit is independently arranged in each bed.

16. The bubbling bed reactor according to claim 15, characterized in that The upper end and the lower end of the catalyst bed are respectively provided with supporting sieve plates.

17. The bubbling bed reactor according to claim 12, characterized in that: The outer wall of the bubbling bed reactor is wrapped with a cooling jacket.

18. A reaction method, characterized in that: The bubbling bed reactor according to any one of claims 12 to 17 is used, comprising: The liquid feed enters the reactor through the liquid distributor and establishes a liquid level that submerges the catalyst bed; The gas feed is respectively sprayed through the first gas distributor and the second gas distributor, and the bubbles from the second gas distributor are turned back in the liquid phase at the catalyst bed; Under the combined effect of the returning bubbles and the rising bubbles from the first gas distributor, the solid catalyst particles are in a tumbling motion state in the bed.

19. The reaction method according to claim 18, characterized in that The reaction method is used for synthesizing ethylene carbonate.

20. The reaction method according to claim 19, characterized in that The liquid feed is ethylene oxide, and the gas feed is carbon dioxide.

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