Gas distribution unit, bubble column reactor and reaction method

Abstract

The application discloses a gas distribution unit, a bubble bed reactor applying the unit and a corresponding reaction method. The gas distribution unit comprises: a first gas distributor arranged below a catalyst bed and bubbling upward; and a second gas distributor arranged inside the catalyst bed, the second gas distributor bubbling downward. The application can make the gas phase feed more uniformly distributed through the gas distribution unit and the corresponding reactor, effectively improve the conversion rate and selectivity of the reactor, and avoid the local concentration of the gas-liquid-solid three phases being too high and the catalyst deactivation phenomenon caused by the intense reaction heat release.

Description

Technical Field

[0001] This invention relates to the field of gas-liquid-solid catalytic reaction technology, and in particular to a gas distribution unit, a bubble bed reactor using the unit, and a corresponding reaction method. Background Technology

[0002] For gas-liquid-solid reactions using granular solid catalysts in bubble reactors, improving the contact time and uniformity of bubbles in the liquid phase is a common concern in the industry. Taking the synthesis of ethylene carbonate (EC) in gas-liquid-solid reactions as an example, ethylene carbonate (EC) is a high-performance, highly polar solvent and fine chemical intermediate, and a potential basic raw material for organic chemicals. Electronic-grade ethylene carbonate is an essential electrolyte solvent for power lithium batteries and a raw material for the synthesis of high-end electrolyte additives such as vinylene carbonate and fluoroethylene carbonate. The main production methods for ethylene carbonate include the phosgene process, transesterification, urea alcoholysis, and the addition of ethylene oxide to carbon dioxide.

[0003] As a greenhouse gas, CO2 has become a pressing issue for all humanity due to the increasing frequency of extreme weather events in recent years. Driven by policies promoting carbon peaking and carbon neutrality, the synthesis of ethylene carbonate (EC) from ethylene oxide and CO2 is a cost-effective and socially beneficial approach with significant future development potential. Industrial production of EC primarily employs homogeneous catalytic processes, which feature simple reactor structures but complex subsequent separation processes, high costs, and significant waste generation. Heterogeneous catalytic technology, on the other hand, eliminates the catalyst in the reaction products, simplifying the separation process compared to homogeneous catalysts and reducing waste emissions.

[0004] Chinese patent application CN106475017A discloses a gas-liquid-solid three-phase reactor for the synthesis of ethylene carbonate from ethylene oxide and carbon dioxide. From bottom to top, it includes a liquid outlet, liquid baffles, a gas inlet, a gas inlet distributor, a lower catalyst support sieve plate, a lower ceramic ball layer, a catalyst layer, an upper ceramic ball layer, an upper catalyst support sieve plate, a liquid inlet, a liquid feed distributor, and a gas outlet. Gas and liquid feeds are radially and uniformly introduced into the catalyst bed through the gas distributor and liquid distributor, respectively. The catalyst bed is fixed inside the reactor by upper and lower ceramic balls and upper and lower support sieve plates. Multiple sets of baffles are installed at the bottom of the reactor, and overflow weirs are set on both sides. Although this design can achieve better gas-liquid separation through overflow weirs, it increases liquid flow resistance, and the gas operating flux is relatively small, limiting the reactor's capacity. The gas cannot be uniformly distributed within the bed, reducing the reactor's conversion rate and selectivity. Furthermore, it is prone to localized excessive concentrations of the gas-liquid-solid three-phase mixture, leading to intense exothermic reactions and 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 make the gas uniformly distributed, thereby improving the reactor conversion rate and selectivity and effectively avoiding catalyst deactivation.

[0006] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0007] The purpose of this 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 phenomenon of catalyst deactivation caused by excessively high local concentration of gas-liquid-solid three phases and violent exothermic reaction.

[0008] To achieve the above objectives, according to a first aspect of the present invention, a gas distribution unit is provided for use in a gas-liquid-solid three-phase bubbling bed reactor, comprising: a first gas distributor disposed below a catalyst bed and bubbling upwards; and a second gas distributor disposed inside the catalyst bed and bubbling downwards.

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

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

[0011] Furthermore, in the above technical solution, the first gas distributor can be uniformly provided with upward bubbling first air holes; the second gas distributor can be uniformly provided with downward bubbling second air holes.

[0012] Furthermore, in the above technical solution, the second air hole can be set in two or more rows; when the second air hole is in two rows, the two rows of air holes are symmetrical and inclined downward, and the angle α between the air hole orientation and the vertical direction is in the range of 25°-65°.

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

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

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

[0016] Furthermore, in the above technical solution, the first air hole can be arranged in two or more rows; when the first air hole is in two rows, the two rows of air holes can be arranged symmetrically and inclined upwards, and the angle β between the air hole orientation and the vertical direction can be in the range of 30°-60°.

[0017] Furthermore, in the above technical solution, the first gas distributor and the second gas distributor can be composed of a main pipe and multiple branch pipes that 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 pipes is 1‰-45‰.

[0018] According to a second aspect of the present invention, a bubble bed reactor is provided for use in any of the preceding gas distribution units.

[0019] Furthermore, in the above technical solution, the reactor also includes a liquid distributor, which is disposed above the catalyst bed and used to provide liquid feed for the reaction; the liquid feed submerges the solid catalyst bed. The porosity of the liquid distributor can be 1‰-65‰.

[0020] Furthermore, in the above technical solution, the reactor may also include: a catalyst bed, which may be one or more layers. When the catalyst bed is multi-layered, the gas distribution unit may be set independently in each bed.

[0021] Furthermore, in the above technical solution, the upper and lower ends of the catalyst bed can be provided with supporting sieve plates 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 the specific reaction conditions.

[0023] According to a third aspect of the present invention, the present invention provides a reaction method using a bubbling bed reactor according to any one of the foregoing, comprising: a liquid feed entering the reactor via a liquid distributor to establish a liquid level that submerges the catalyst bed; a gas feed being sprayed through a first gas distributor and a second gas distributor to form a counter-spray, wherein bubbles from the second gas distributor circulate back and forth in the liquid phase at the catalyst bed; and under the combined action of the circulating bubbles and the rising bubbles from the first gas distributor, the solid catalyst particles are in a tumbling motion state within the bed.

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

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

[0026] 1) In this invention, the gas entering the reactor through the second gas distributor has a downward initial velocity. Under the buoyancy of the liquid feed, the bubbles generated by the second gas distributor located in the catalyst bed run back and forth, which makes the bubbles stay in the catalyst bed for a longer time, promoting 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 rolling motion state throughout the reaction process, making the gas-liquid-solid reaction more complete.

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

[0028] 3) The downward tilting second air hole setting of the present invention gives the gas entering the reactor an initial velocity that is tilted downward. The velocity has a downward component in the vertical direction and a horizontal outward component. This ensures that the gas in the lower part of the second gas distributor is evenly dispersed, while the excess gas that has not had time to react will change its direction of motion and move upward due to buoyancy after a period of time. At the same time, it makes the bubble coverage area wider and ensures that the gas in the upper part of the distributor is also evenly distributed.

[0029] 4) When the second gas distributor is set in two layers, 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 gas hole tilt angle (i.e., included angle α) of the upper second gas distributor greater than the corresponding tilt angle of the lower layer. This ensures that more gas moves upward due to buoyancy, which can further ensure that the gas is evenly distributed in the reactor and improve the conversion rate and selectivity of the reactor.

[0030] 5) When two or more layers of second gas distributors are set, by setting the second gas distributors of adjacent layers as a whole to have an inclination angle δ in the horizontal direction, the staggered arrangement of second gas distributors of different layers 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 in the bubbling bed reactor of the present invention is preferably a single layer; when there is more than one catalyst bed, a first gas distributor needs to be installed in the space between the beds, and at least one second gas distributor needs to be installed in each bed, that is, the reactor is divided into two relatively independent reaction beds and each is equipped with its own gas distributor, which can reduce the degree of backmixing of the system and improve the reaction rate and conversion rate. However, the temperature control and feed need to be adjusted accordingly to avoid the reactor overheating 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 advantages compared with the single reactor in the prior art (the prior art usually requires two or more reactors to ensure a certain optimization effect).

[0033] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it according to the contents of the specification, and to make the above and other objects, technical features and advantages of the present invention easier to understand, one or more preferred embodiments are listed below and described in detail with reference to the accompanying drawings. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the structure of the bubble bed reactor of the present invention.

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

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

[0037] Figure 4 This is a schematic diagram of the cross-section of the branch pipe of the first gas distributor of the present invention (showing the upwardly inclined air holes).

[0038] Figure 5 This is a schematic diagram of the cross-section of the branch pipe of the second gas distributor of the present invention (showing the downwardly inclined air holes).

[0039] Explanation of key figure labels:

[0040] 1-Bubble bed reactor, 11-Catalyst layer, 12A-First gas distributor, 12B / 12C-Second gas distributor, 120-Vacuum pore, 121-Main gas distribution pipe, 122-Branch gas distribution pipe, 13-Liquid distributor, 14-Catalyst support sieve plate, 15-Cooling jacket, 16-Gas outlet, 17-Liquid outlet. Detailed Implementation

[0041] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0042] Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprises" shall be understood to include the stated elements or components without excluding other elements or other components.

[0043] In this document, for ease of description, spatial relative terms such as “below,” “under,” “down,” “above,” “above,” “upper,” etc., are used to describe the relationship of one element or feature to another element or feature in the accompanying drawings. It should be understood that spatial relative terms are intended to encompass different orientations of an object in use or operation, in addition to those depicted in the figures. For example, if an object in the figure is flipped, an element described as “below” or “under” another element or feature would be oriented “above” that element or feature. Thus, the exemplary term “below” can encompass both the downward and upward orientations. An object may also have other orientations (rotated 90 degrees or other orientations), and the spatial relative terms used herein 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 define specific positions or relative relationships. In other words, in some embodiments, the terms "first," "second," etc., can also be used interchangeably.

[0045] The gas distribution unit of this invention and the bubbling bed reactor using this unit are applicable to gas-liquid-solid reactions using a bubbling bed reactor. This invention is illustrated using the gas-liquid-solid catalytic reaction process for synthesizing ethylene carbonate as an example. Addressing the problems of uneven gas phase distribution within the reactor reducing reactor conversion and selectivity, and excessively high local gas concentrations leading to intense exothermic reactions and catalyst deactivation, this invention effectively overcomes the reactor design challenges related to these issues. The inventors discovered that uniform gas distribution within a gas-liquid-solid three-phase reactor has always been a design challenge. Incomplete gas distribution inevitably leads to decreased reaction conversion and selectivity. When the local gas concentration within the reactor is excessively high, it is more likely to cause excessive exothermic reactions. If the heat cannot dissipate quickly enough, the catalyst may deactivate due to high temperatures. More seriously, thermal runaway may occur, affecting the inherent safety of the reaction. The gas distribution unit provided by this invention and the bubble bed reactor for multiphase catalytic synthesis of ethylene carbonate using this unit have advantages such as uniform gas phase feed distribution, high reaction conversion rate and selectivity, large operating load, and easier control of reactor temperature during ethylene carbonate synthesis. They are suitable for large-scale industrial production of high-purity electronic-grade ethylene carbonate.

[0046] like Figure 1 As shown, this invention provides a bubble bed reactor 1 for synthesizing ethylene carbonate. The reactor has a cylindrical tank structure. Based on the fact that the reaction is exothermic, a cooling jacket 15 is wrapped around the outer wall of the bubble bed reactor 1 to allow a cooling medium to be introduced into the jacket for heat removal. The bubble 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 configured as one or more layers. When the catalyst bed is multi-layered, the gas distribution unit 12 is independently installed in each bed layer. This invention preferably uses a single catalyst bed 11. When there are more than one catalyst bed 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 needs to be installed in each bed layer. The advantage of a two-layer reactor bed is that the reaction system is a fully mixed system with severe backmixing of the gas, liquid, and solid phases. Dividing the reactor into two relatively independent reaction beds, each equipped with its own gas distributor, can reduce the degree of backmixing and improve the reaction rate and conversion rate. However, temperature control and feed need to be adjusted accordingly to avoid reactor overheating. Supporting sieves 14 are provided at the upper and lower ends of the catalyst bed 11. Since the solid catalyst used in this invention is granular and immersed in the liquid feed, the particles are in a tumbling motion during the reaction. Therefore, the supporting sieves 14 at the upper and lower ends can confine the granular solid catalyst within the catalyst bed layer. The liquid distributor 13 is located above the catalyst bed and is used to provide the liquid feed ethylene oxide for the synthesis of ethylene carbonate, which immerses the solid catalyst bed. Specifically, the liquid distributor 13 has a combination of main pipe and branch pipe. At least one row of small holes facing downwards is opened on the main pipe and 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, with an opening rate of 1‰-95‰, and the opening rate is preferably 1‰-65‰.

[0047] Further as Figure 1 As shown, the gas distribution unit 12 for synthesizing ethylene carbonate of the present invention is applied in a gas-liquid-solid three-phase bubbling bed reactor and provides the carbon dioxide gas required for the reaction. The gas distribution unit 12 includes: a first gas distributor 12A and a second gas distributor 12B / 12C. Preferably, but not limitingly, both the first gas distributor and the second gas distributor consist of a main pipe 121 perpendicular to each other and multiple branch pipes 122. The coverage of the branch pipes 122 is adapted to the cross-section of the bubbling bed reactor (see reference). Figure 2 and Figure 3 The opening ratio of the main pipe and branch pipes is 1‰-45‰. The first gas distributor 12A is located below each catalyst bed layer, and the first gas distributor 12A has uniformly formed upward-bubbling first gas holes (see reference). Figure 4(Vascular pores 120). Second gas distributors 12B / 12C are disposed inside each catalyst bed layer, and downward-bubbling second pores are uniformly formed on the second gas distributors (see reference). Figure 5 In the first gas distributor 12A, the bubbles formed by the second gas distributor 12B / 12C are first injected downwards and then rise back upwards in the liquid phase of ethylene oxide. This invention utilizes the viscosity of the liquid-phase ethylene oxide feed at a certain reaction temperature, and the downward initial velocity of the carbon dioxide gas entering the reactor through the second gas distributor 12B / 12C. Under the buoyancy of the liquid-phase feed, excess gas that has not reacted in time will change its direction of motion after a period of time, becoming upwards. That is, the bubbles generated by the second gas distributor located in the catalyst bed, through their reversal motion, allow the bubbles to remain in the catalyst bed for a longer time, promoting gas-liquid mass transfer. Furthermore, since the bubbles generated by the first gas distributor 12A always move upwards, the different trajectories of the bubbles increase the turbulence of the liquid phase. Under the turbulence of the liquid phase, the catalyst particles are always in a state of tumbling motion throughout the reaction process, making the gas-liquid-solid reaction more complete.

[0048] Further as Figure 1 As shown, the second gas distributors 12B / 12C can be arranged in one to four layers at different heights within the catalyst bed. Considering the space constraints of the reactor and the need to provide sufficient operating space for bubble backflow, this invention preferably employs two layers of second gas distributors, i.e. Figure 1 The second gas distributor 12B and the second gas distributor 12C are described. It should be noted that the purpose of this invention can be achieved by arranging only one layer of second gas distributors in the catalyst bed; when multiple layers are arranged, the installation height of the uppermost second gas distributor is less than or equal to 80% of the height of the catalyst bed. Second gas holes are provided on the main and branch pipes of the second gas distributor, with two or more rows, preferably two to five rows, and an opening ratio of 1‰-60‰, preferably 1‰-45‰. When there are two rows of second gas holes, the two rows of holes are symmetrical and inclined downwards (see reference). Figure 5 When there are more than two rows, the openings are symmetrically distributed along the lowest point of the tube. The angle α between the opening orientation and the vertical direction ranges from 25° to 65°. The downward-sloping arrangement of the second vent ensures that the carbon dioxide gas entering the reactor has an initial downward velocity. This velocity has a downward component in the vertical direction and a horizontal outward component. This ensures that the gas is evenly dispersed in the lower region of the gas distributor, while excess gas that has not yet reacted will change its direction of motion and move upward due to buoyancy after a period of time. This also makes the bubble coverage area wider, thus ensuring that the gas is also evenly distributed in the upper region of the distributor.

[0049] Furthermore, when the second gas distributor is configured with two layers, i.e. Figure 1The reactor consists of a lower second gas distributor 12B and an upper second gas distributor 12C. The included angle α between the second gas vents of the upper second gas distributor 12C is greater than or equal to the included angle α between the second gas vents of the lower second gas distributor 12B. Preferably, but not limitingly, the difference in the included angle α between the upper and lower layers is 5°-25°. With this arrangement, the lower region of the upper layer 12C contains more gas than the lower region of the lower layer 12B. The larger opening angle α of the upper layer 12C allows for a smaller downward velocity component of the gas entering the reactor through the upper second gas distributor 12C, ensuring that more gas ultimately moves upward due to buoyancy. This arrangement further ensures uniform distribution of carbon dioxide gas within the reactor, improving the reactor's conversion rate and selectivity.

[0050] Further as 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 overall tilt angle δ in the horizontal direction, where the angle δ ranges from 0° to 135°. Specifically, according to the present invention... Figure 2 The first gas distributor 12A, as illustrated in the diagram, serves as a reference (the main pipe 121 of the first gas distributor is horizontally positioned, and each branch pipe 122 is vertically positioned). The lower second gas distributor 12B can be configured in the same way as the first gas distributor 12A, while the upper second gas distributor 12C can be rotated counterclockwise by an angle δ in the horizontal direction. If there are more than two layers of second gas distributors, this arrangement forms an alternating arrangement of different layers of second gas distributors. This alternating arrangement of the second gas distributors can further increase the degree of gas-liquid turbulence, promote mixing, and improve the conversion rate and selectivity of the reaction.

[0051] Further as Figure 2 , 4 As shown, the first gas distributor 12A at the bottom of the reactor has upward-facing openings. When the openings are in a row, they are located at the highest points of the main gas distribution pipe 121 and the branch gas distribution pipe 122. Preferably, this invention employs two rows of symmetrically distributed, upward-sloping gas holes 120, with the openings forming a certain angle β with the vertical direction. The value of β ranges from 0° to 90°, preferably from 30° to 60°. The orientation of the openings of the first gas distributor 12A ensures that the gas entering the reactor has an initial upward-sloping velocity, with an upward component in the vertical direction. This arrangement maximizes the uniform distribution of the gas phase within the reactor, improving the reactor's conversion rate and selectivity.

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

[0053] Liquid ethylene oxide enters reactor 1 through liquid distributor 13, establishing a liquid level within the reactor to submerge the catalyst bed. Gaseous CO2 enters reactor 1 through first gas distributor 12A and second gas distributors 12B / 12C in a bubbling state. Because the pores of the first gas distributor 12A are inclined upwards, CO2 flows upwards at an initial velocity through the lower catalyst support sieve plate 14 before entering the catalyst bed 11 for reaction. Because the pores of the second gas distributors 12B and 12C are inclined downwards, CO2 enters the catalyst bed 11 at an initial velocity downwards. When the downward velocity decreases to zero due to resistance, buoyancy causes it to turn back upwards, ensuring a sufficiently uniform distribution of CO2 between the catalyst support sieve plate 14 and the second gas distributor 12B, as well as between the second gas distributor 12B and the second gas distributor 12C, thus improving reaction conversion and selectivity. Liquid ethylene oxide and gaseous CO2 undergo a gas-liquid-solid three-phase catalytic reaction in catalyst bed 11 to produce ethylene carbonate. The product flows out of reactor 1 in liquid form through liquid outlet 17, while unreacted CO2 is discharged from gas outlet 16 at the top of reactor 1.

[0054] Example 1

[0055] The reactor has a diameter of 1600 mm and a single catalyst bed. Both the first and second gas distributors consist of a main gas distribution pipe 121 and five branch gas distribution pipes 122, with the main pipe and branch pipes perpendicular to each other. The second gas distributor 12C is rotated counterclockwise relative to the first gas distributor 12A by an angle δ, where δ = 0°. The second gas distributors 12B and 12C have two rows of symmetrically distributed, downward-sloping gas holes, with the openings forming a certain angle α with the vertical direction, and α... 12B =α 12C =45°. The first gas distributor 12A has two rows of symmetrically distributed, upward-sloping gas holes, with the openings forming 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 opening ratio of all gas distributors is 25‰, and the opening ratio of the liquid distributor 13 is 45‰. The synthesis of ethylene carbonate from ethylene oxide and carbon dioxide is carried out in the above reactor. A commercially available solid catalyst is used, and the conversion rate of a single reactor is 87.1%, with a selectivity of 96.5%.

[0056] Example 2

[0057] The reactor has a diameter of 1600 mm and a single catalyst bed. Both the first and second gas distributors consist of a main gas distribution pipe 121 and five branch gas distribution pipes 122, with the main pipe and branch pipes perpendicular to each other. The second gas distributor 12C is rotated counterclockwise relative to the first gas distributor 12A by an angle δ, where δ = 30°. The second gas distributors 12B and 12C have two rows of symmetrically distributed, downward-sloping gas holes, with the openings forming a certain angle α with the vertical direction, and α... 12B =45°, α 12C =55°. The first gas distributor 12A has two rows of symmetrically distributed, upward-sloping gas holes, with the openings forming 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 opening ratio of all gas distributors is 25‰, and the opening ratio of the liquid distributor 13 is 45‰. Ethylene oxide and carbon dioxide are reacted to synthesize ethylene carbonate in the above reactor. The catalyst used is 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 was designed according to Example 2. The reactor in Example 2 used a reaction temperature of 100°C, while Comparative Example 1 used a reaction temperature of 110°C. Ethylene oxide and carbon dioxide were reacted to synthesize ethylene carbonate in the above reactors. The same solid catalyst was used. The conversion rate of a single reactor was 93.1%, and the selectivity was 99.0%. It can be seen that for the reaction of the present invention, the increase of temperature will lead to a change in the viscosity of the liquid phase. When the reaction temperature of Comparative Example 1 is increased, the corresponding conversion rate and selectivity will decrease.

[0060] Comparative Example 2

[0061] The reactor has a diameter of 1600 mm and a single catalyst bed. Both the first and second gas distributors consist of a main gas distribution pipe 121 and five branch gas distribution pipes 122, with the main and branch pipes perpendicular to each other. In Comparative Example 2, only one first gas distributor 12A is used, with two rows of symmetrically distributed, upward-sloping gas holes at an angle β (β = 45°) to the vertical direction. No second gas distributor is installed inside the catalyst bed. The opening ratio of the first gas distributor 12A is 25‰, and the opening ratio of the liquid distributor 13 is 45‰. The synthesis of ethylene carbonate from ethylene oxide and carbon dioxide is carried out in the above reactor using 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 single catalyst bed. Both the first and second gas distributors consist of a main gas distribution pipe 121 and five branch gas distribution pipes 122, with the main pipe and branch pipes perpendicular to each other. The second gas distributor 12B has two rows of symmetrically distributed, downward-sloping gas holes, with the openings forming 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 within the bed. The opening ratio of the second gas distributor 12B is 25‰, and the opening ratio of the liquid distributor 13 is 45‰. The synthesis of ethylene carbonate from ethylene oxide and carbon dioxide takes place in the above reactor, using 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 single catalyst bed. Both the first and second gas distributors consist of a main gas distribution pipe 121 and five branch gas distribution pipes 122, with the main pipe and branch pipes perpendicular to each other. The second gas distributor 12C is rotated counterclockwise relative to the first gas distributor 12A by an angle δ, where δ = 30°. The second gas distributors 12B and 12C have two rows of symmetrically distributed, downward-sloping gas holes, with the openings forming a certain angle α with the vertical direction, and α... 12B =60°, α 12C =30°. The first gas distributor 12A has two rows of symmetrically distributed, upward-sloping holes, with the openings forming an 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 opening ratio of all gas distributors is 25‰, and the opening ratio of the liquid distributor 13 is 45‰. The synthesis of ethylene carbonate from ethylene oxide and carbon dioxide is carried out in the above reactor, using 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 single catalyst bed. Both the first and second gas distributors consist of a main gas distribution pipe 121 and five branch gas distribution pipes 122, with the main pipe and branch pipes perpendicular to each other. The second gas distributor 12C is rotated counterclockwise relative to the first gas distributor 12A by an angle δ, where δ = 45°. The second gas distributors 12B and 12C have two rows of symmetrically distributed, downward-sloping gas holes, with the openings forming a certain angle α with the vertical direction, and α... 12B =60°, α 12C=70°. The first gas distributor 12A has two rows of symmetrically distributed, upward-sloping holes, with the openings forming 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 opening ratio of all gas distributors is 15‰, and the opening ratio of the liquid distributor 13 is 40‰. The synthesis of ethylene carbonate from ethylene oxide and carbon dioxide is carried out in the above reactor, using 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 single catalyst bed. Both the first and second gas distributors consist of a main gas distribution pipe 121 and five branch gas distribution pipes 122, with the main pipe and branch pipes perpendicular to each other. The second gas distributor 12C is rotated counterclockwise relative to the first gas distributor 12A by an angle δ, where δ = 30°. The second gas distributors 12B and 12C have two rows of symmetrically distributed, downward-sloping gas holes, with the openings forming a certain angle α with the vertical direction, and α... 12B =45°, α 12C =55°. The first gas distributor 12A has two rows of symmetrically distributed, upward-sloping holes, with the openings forming an 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 opening ratio of all gas distributors is 8‰, and the opening ratio of the liquid distributor 13 is 15‰. The synthesis of ethylene carbonate from ethylene oxide and carbon dioxide is carried out in the above reactor, using 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 the catalyst bed consists of two layers. Both the first and second gas distributors consist of a main gas distribution pipe 121 and five branch gas distribution pipes 122, with the main and branch pipes perpendicular to each other. In this embodiment, a first gas distributor 12A and a second gas distributor 12B are installed at corresponding positions in the two beds. The opening angle α of the second gas distributors 12B within the bed is 45°. The opening angle β of the first gas distributors 12A at the bottom of the bed is 45°. The two second gas distributors 12B are installed at 25% of the height of the corresponding catalyst bed 11. The opening ratio of all gas distributors is 25‰, and the opening ratio of the liquid distributor 13 is 45‰. Ethylene oxide and carbon dioxide are reacted to synthesize ethylene carbonate in the above reactor. The same solid catalyst is used, and the conversion rate of a single reactor is 94.8%, with a selectivity greater than 99.9%.

[0072] The foregoing description of specific exemplary embodiments of the present invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. Any simple modifications, equivalent changes, and alterations made to the foregoing exemplary embodiments should fall within the scope of protection of the present invention.

Claims

1. A gas distribution unit, characterized in that, Applications in gas-liquid-solid three-phase bubbling bed reactors, including: A first gas distributor is disposed below the catalyst bed and bubblees upward; the first gas distributor has uniformly opened first gas holes that bubble upward. A second gas distributor is disposed inside the catalyst bed, and the second gas distributor bubblees downwards; the second gas distributor has uniformly distributed second gas holes that bubble downwards; the second gas holes are arranged in two or more rows; when there are two rows of second gas holes, the two rows of gas holes are symmetrical and inclined downwards, and the angle between the gas hole orientation and the vertical direction is α; the second gas distributor is arranged in 2 to 4 layers at different heights in the catalyst bed; when the second gas distributor is arranged in two layers, the angle α of the second gas holes in the upper layer is greater than the angle α of the second gas holes in the lower layer.

2. The gas distribution unit according to claim 1, characterized in that, The catalyst bed contains particulate solid catalyst that is confined within the bed.

3. The gas distribution unit according to claim 1, characterized in that, The included angle α ranges from 25° to 65°.

4. The gas distribution unit according to claim 1, characterized in that, The difference in the included angle α between the upper and lower layers is 5°-25°.

5. The gas distribution unit according to claim 1, characterized in that, When the second gas distributor is provided in two or more layers, the second gas distributors of adjacent layers have an overall tilt angle δ in the horizontal direction, and the angle range of δ is 0°-135°.

6. The gas distribution unit according to claim 1, characterized in that, The installation height of the second gas distributor in the top layer is less than or equal to 80% of the height of the catalyst bed.

7. The gas distribution unit according to claim 1, characterized in that, The first air hole is arranged in two or more rows; when the first air hole is arranged in two rows, the two rows of air holes are symmetrical and inclined upward, and the angle β between the air hole orientation and the vertical direction is in the range of 30°-60°.

8. The gas distribution unit according to claim 1, characterized in that, The first gas distributor and the second gas distributor consist of a main pipe and multiple branch pipes perpendicular to each other. The coverage area 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 pipes is 1‰-45‰.

9. A bubble bed reactor, characterized in that, Applied to the gas distribution unit according to any one of claims 1 to 8.

10. The bubbling bed reactor according to claim 9, characterized in that, Also includes: A liquid distributor, positioned above the catalyst bed, is used to provide liquid-phase feed for the reaction; The liquid feed is used to immerse the solid catalyst bed.

11. The bubbling bed reactor according to claim 10, characterized in that, The orifice ratio of the liquid distributor is 1‰-65‰.

12. The bubble bed reactor according to claim 9, characterized in that, Also includes: The catalyst bed may be one or more layers. When the catalyst bed is multi-layered, the gas distribution unit is set independently in each bed.

13. The bubbling bed reactor according to claim 12, characterized in that, The catalyst bed is provided with supporting sieve plates at the upper and lower ends, respectively.

14. The bubbling bed reactor according to claim 9, characterized in that, The outer wall of the bubbling bed reactor is wrapped with a cooling jacket.

15. A reaction method, characterized in that, Using the bubbling bed reactor as described in any one of claims 9 to 14, comprising: The liquid feed enters the reactor via a liquid distributor and establishes a liquid level that submerges the catalyst bed. The gas feed is sprayed through the first gas distributor and the second gas distributor respectively to form a counter-jet, and the bubbles from the second gas distributor are circulated back and forth in the liquid phase at the catalyst bed; Under the combined action of the refluxing bubbles and the rising bubbles from the first gas distributor, the solid catalyst particles are in a tumbling motion within the bed.

16. The reaction method according to claim 15, characterized in that, The reaction method is used to synthesize ethylene carbonate.

17. The reaction method according to claim 16, characterized in that, The liquid feed is ethylene oxide, and the gas feed is carbon dioxide.

Images