Confined fluidization continuous reactor for anthraquinone hydrogenation

Abstract

The invention discloses a confinement fluidization continuous reactor for anthraquinone hydrogenation, and belongs to the technical field of reactor design. The main structure comprises a feeding area (1) and a reaction area (2), the feeding area (1) plays a role in pre-dispersing gas and liquid, the reaction area (2) is composed of a plurality of constraint bodies which are connected through threads, screens are installed among the constraint bodies, reactants and products can penetrate through the screens, but catalysts cannot penetrate through the screens, and limited fluidization can only be carried out in a certain constraint body. The reactor can reduce gas-phase and liquid-phase flow rates required by a catalyst to reach an optimal fluidized state, so that the wear degree of the catalyst is reduced, and the generation amount of fine powder is reduced; in addition, the spatial distribution of the catalyst in the whole hydrogenation tower is more uniform, and obvious dense-phase regions and dilute-phase regions do not exist, so that the utilization rate of the catalyst is improved.

Description

Technical Field

[0001] The present invention belongs to the field of reactor design, and particularly relates to a novel continuous confined fluidized bed reactor applied to anthraquinone hydrogenation reaction. Background Art

[0002] Hydrogen peroxide, with the chemical formula H 2 O 2 , and its aqueous solution is called "hydrogen peroxide solution", which is mainly used in the production of important chemicals such as caprolactam, propylene oxide, and iron phosphate, pulp and fabric bleaching, sewage treatment and other fields. Industrial plants all use the anthraquinone method to produce hydrogen peroxide, and according to the type of reaction tower used in the hydrogenation process, it is divided into two processes: fixed bed and fluidized bed. Although the production capacity of domestic fixed bed plants still accounts for about 70% of the total production capacity at present, affected by relevant policies and the integration of hydrogen peroxide-downstream applications, the proportion of fluidized bed plants is increasing rapidly.

[0003] During the operation of a traditional fluidized bed, catalyst particles are in a fluidized state under the combined action of the working fluid and hydrogen. Compared with the fixed bed process, the fluidized bed process has many advantages, such as: the temperature in the bed is more uniform than that in the fixed bed and there is no local hot spot; the working fluid in the fluidized bed is approximately in a completely mixed flow, and abnormal conditions such as uneven flow and channeling are not likely to occur; the volume of a single set of equipment is small and the production capacity is higher. However, during the operation of a traditional fluidized bed, the catalyst particles collide frequently with equipment such as hydrogenation towers and pipelines, which easily causes serious wear of the catalyst and generates a large amount of fine powder, resulting in a rapid increase in the pressure difference of the back-end filter and forcing frequent shutdowns to replace the filter; in addition, the distribution of catalyst particles in the bed is not uniform, and the concentration of the catalyst in the lower part of the fluidized bed is significantly higher than that in the middle and upper parts. Compared with uniform distribution, the utilization rate of the catalyst is low. Summary of the Invention

[0004] To solve the above problems, the present invention provides a confined fluidized continuous reactor applied to anthraquinone hydrogenation reaction, which mainly consists of two parts: a feeding area and a reaction area. Among them, the feeding area mainly includes a gas distributor and a liquid distributor, and the reaction area mainly includes a confinement body filled with catalyst and a thermal insulation jacket. The specific process is as follows: After hydrogen and the working fluid enter the feeding area, they are dispersed by the gas distributor and the liquid distributor respectively, and then sequentially pass through each confinement body filled with catalyst from bottom to top. Affected by the flow of gas and the working fluid, the catalyst is always in a fluidized state during the reaction and is restricted to fluidize in a certain confinement body. The working fluid and the remaining gas after the reaction enter the gas-liquid separation tank for preliminary separation. The gas phase enters the tube side of the shell-and-tube condenser, and cooling water is introduced into the shell side. The condensed liquid returns to the gas-liquid separator, and the gas is discharged. The liquid-phase reaction products collected in the gas-liquid separation tank are regularly transported to the hydrogenated liquid storage tank, and a filter is installed between the gas-liquid separation tank and the hydrogenated liquid storage tank.

[0005] The outer side of the cylinder is dense, and gas or working fluid cannot pass through; the upper bottom surface of the cylinder has internal threads, and the lower bottom surface has external threads. Two adjacent binding bodies above and below are fixed by threads, and a gasket and a sieve are also installed therein. The aperture of the sieve is 20 - 200 μm.

[0006] The pressure in the reaction zone is 0.10 - 0.50 MPa, and the temperature in the reaction zone is 30 - 80 °C.

[0007] Furthermore, the binding body is a hollow cylinder, and the aspect ratio of length to diameter is 1:1 - 5:1.

[0008] The beneficial effects of the present invention are as follows: (1) Due to the confinement and redispersion effects of the sieve, both the gas-phase and liquid-phase flow rates required for the catalyst to reach the optimal fluidization state are significantly reduced. Therefore, the degree of catalyst wear is greatly reduced, and the generation amount of fine powder is significantly reduced. This not only reduces the loss of the catalyst during operation but also greatly improves the safety of the device operation. (2) The spatial distribution of the catalyst in the entire hydrogenation tower is more uniform, and there is no obvious dense phase region and dilute phase region, thereby improving the utilization rate of the catalyst. In addition, according to the reaction characteristics, catalysts with different performances can be filled in different regions, so as to achieve high conversion rate and high selectivity simultaneously. Description of the Drawings

[0009] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. The drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings, where:

[0010] Figure 1 is the flow chart of the confined fluidization continuous reactor device for anthraquinone hydrogenation of the present invention. 1 - Feed zone; 2 - Inlet gas pipe; 3 - Gas distributor; 4 - Inlet liquid pipe; 5 - Liquid distributor; 6 - Binding body; 7 - Gas-liquid separation tank; 8 - Shell-and-tube condenser; 9 - Filter; 10 - Hydrogenated liquid storage tank; 11 - Hydrogenated liquid and hydrogen; 12 - Hydrogen with entrained hydrogenated liquid; 13 - Vent tail gas; 14 - Condensed hydrogenated liquid.

[0011] Figure 2 is the structural schematic diagram of the feed zone. 2 - Inlet gas pipe; 3 - Gas distributor; 4 - Inlet liquid pipe; 5 - Liquid distributor.

[0012] Figure 3 is the structural schematic diagram of a single binding body in the reaction zone. Detailed Embodiments

[0013] The technical solutions in the embodiments of the present invention will be clearly and completely described below. The described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0014] Example 1

[0015] A confined fluidized continuous reactor is used for anthraquinone hydrogenation reaction. The reactor feed zone includes an inlet gas pipe, an inlet liquid pipe, a gas distributor, and a liquid distributor. The gas distributor in the feed zone is a 304 stainless steel sintered metal mesh with a pore size of 60 μm. The working fluid is a mixed solution of 2-pentylanthraquinone, 1,2,4-trimethylbenzene, and tetrabutylurea (where the concentration of 2-pentylanthraquinone is 250 g / L, and the volume ratio of 1,2,4-trimethylbenzene to tetrabutylurea is 7:3). The confinement bodies in the reaction zone are made of 304 stainless steel, with an outer diameter of 2.00 mm, an inner diameter of 1.00 mm, and a height of 8.00 mm, where the heights of the inner and outer threaded parts are both 1.00 mm. The total number of confinement bodies is 16, and a wire woven mesh made of 304 stainless steel with a pore size of 100 μm is placed between each confinement body. The confinement bodies are filled with microspherical Pd / Al 2 O 3 catalyst, where the mass fraction of palladium is 2.00%, and the mass of the catalyst in each confinement body is 15.0 mg. The gas flow rate during the reaction process is controlled at 2.0 L / min, the working fluid flow rate is 0.60 L / h, the reaction temperature is 55 °C, the pressure in the feed zone is 0.10 MPa, and the hydrogenated liquid is taken out from the back end of the filter every 30 min for reaction performance evaluation and calculation of the production capacity of the catalyst.

[0016] Example 2

[0017] The same device as in Example 1 is used, and the working fluid is a mixed solution of 2-ethylanthraquinone, 1,2,4-trimethylbenzene, and tetrabutylurea (where the concentration of 2-ethylanthraquinone is 120 g / L, and the volume ratio of 1,2,4-trimethylbenzene to tetrabutylurea is 6:4). The total number of confinement bodies in the reaction zone is 16, and a wire woven mesh made of 304 stainless steel with a pore size of 60 μm is placed between each confinement body. The confinement bodies are filled with microspherical Pd / Al 2 O 3 catalyst, where the mass fraction of palladium is 1.50%, and the mass of the catalyst in each confinement body is 20.0 mg. The gas flow rate during the reaction process is controlled at 3.0 L / min, the working fluid flow rate is 0.40 L / h, the reaction temperature is 65 °C, the pressure in the feed zone is 0.20 MPa, and the hydrogenated liquid is taken out from the back end of the filter every 30 min for reaction performance evaluation and calculation of the production capacity of the catalyst.

[0018] Example 3

[0019] Using the same device as in Example 1, the working fluid is a mixed solution of 2-ethylanthraquinone, 1,2,4-trimethylbenzene and tetrabutylurea (where the concentration of 2-ethylanthraquinone is 120 g / L, and the volume ratio of 1,2,4-trimethylbenzene to tetrabutylurea is 6:4). The total number of confinement bodies in the reaction zone is 16. A wire mesh made of 304 stainless steel with a pore size of 60 μm is placed between the ten confinement bodies near the lower part, and 20.0 mg of microspherical Pd / Al 2 O 3 catalyst with a palladium mass fraction of 1.50% is filled in each confinement body; a wire mesh made of 304 stainless steel with a pore size of 100 μm is placed between the six confinement bodies near the upper part, and 15.0 mg of microspherical Pd / Al 2 O 3 catalyst with a palladium mass fraction of 2.00% is filled in each confinement body. Control the gas flow rate in the reaction process to be 2.5 L / min, the working fluid flow rate to be 0.50 L / h, the reaction temperature to be 60 °C, and the pressure in the feed zone to be 0.15 MPa. Take out the hydrogenated liquid from the back end of the filter every 30 min for reaction performance evaluation and calculate the production capacity of the catalyst.

[0020] Comparative Example

[0021] Using the same device as in Example 1, only the sieves at two places, namely between the feed zone and the bottom confinement body and at the top confinement body, are retained, and 240.0 mg of the same microspherical Pd / Al 2 O 3 catalyst as in Example 1 is filled in the bottom confinement body. The working fluid and process parameters used in the reaction are the same as those in Example 1. Take out the hydrogenated liquid from the back end of the filter every 30 min for reaction performance evaluation and calculate the production capacity of the catalyst.

[0022] Table 1 Comparison of production capacity between the confined-fluidized continuous reactor and the fluidized bed reactor in the reaction of anthraquinone hydrogenation to hydrogen peroxide

[0023]

[0024] The above are only the embodiments of the present invention, and do not limit the scope of the present invention accordingly. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, shall be included in the patent scope of the present invention by the same token.

Claims

1. A confined fluidized continuous reactor for anthraquinone hydrogenation, characterized in that: It includes two parts: a feed zone and a reaction zone; the feed zone includes a gas distributor and a liquid distributor, and the reaction zone includes a restraining body filled with catalyst and a heat-insulating jacket; the specific process is as follows: after hydrogen and working liquid enter the feed zone, they are dispersed by the gas distributor and the liquid distributor respectively, and then pass through each restraining body filled with catalyst from bottom to top in sequence; The catalyst is always in a fluidized state during the reaction and is confined to a certain binding body for fluidization; the working liquid and the remaining gas after the reaction enter the gas-liquid separation tank for preliminary separation, the gas phase enters the tube side of the shell-and-tube condenser, the shell side is passed through cooling water, the condensed liquid returns to the gas-liquid separator, and the gas is vented; the liquid reaction products collected in the gas-liquid separation tank are regularly transported to the hydrogenation liquid storage tank, and a filter is installed between the gas-liquid separation tank and the hydrogenation liquid storage tank; The outer side of the restraining body is dense, and gas or working fluid cannot pass through; the two upper and lower adjacent restraining bodies are fixed by threads, and gaskets and screens are also installed in the restraining body. The above-mentioned screen is a detachable and replaceable metal mesh with a mesh aperture of 20 to 200 μm; The pressure in the reaction zone is 0.10-0.50 MPa, and the temperature in the reaction zone is 30-80°C.

2. A method for using the reactor as claimed in claim 1, characterized in that: Used for anthraquinone hydrogenation reaction; the gas distributor in the feed zone is a metal mesh with a pore size of 60μm, and the working fluid is a mixed solution of 2-pentylanthraquinone, 1,2,4-trimethylbenzene and tetrabutylurea; the concentration of 2-pentylanthraquinone is 250g / L, and the volume ratio of 1,2,4-trimethylbenzene to tetrabutylurea is 7:3; the restraining body in the reaction zone is made of 304 stainless steel, with an outer diameter of 2.00mm, an inner diameter of 1.00mm, and a height of 8.00mm, wherein the inner thread and the outer thread part are The height is 1.00mm; there are a total of 16 restraining bodies, and a metal mesh with a pore size of 100μm is placed between each restraining body; the restraining bodies are filled with microspherical Pd / Al2O3 catalysts with a particle size of 110-250μm, in which the mass fraction of palladium is 2.00%, and the mass of catalyst in each restraining body is 15.0mg; the gas flow rate of the reaction process is controlled at 2.0L / min, the working liquid flow rate is 0.60L / h, the reaction temperature is 55℃, and the pressure in the feed zone is 0.10MPa.

3. A method for using the reactor as claimed in claim 1, characterized in that: The working liquid is a mixed solution of 2-ethylanthraquinone, 1,2,4-trimethylbenzene and tetrabutylurea; wherein the concentration of 2-ethylanthraquinone is 120 g / L, and the volume ratio of 1,2,4-trimethylbenzene to tetrabutylurea is 6:4; the number of the restraining bodies in the reaction zone is 16 in total, and a metal mesh with an aperture of 60 μm is placed between each restraining body; the restraining bodies are filled with microspherical Pd / Al2O3 catalysts with a particle size of 75 to 200 μm, wherein the mass fraction of palladium is 1.50%, and the mass of the catalyst in each restraining body is 20.0 mg; the gas flow rate of the reaction process is controlled to be 3.0 L / min, the working liquid flow rate is 0.40 L / h, the reaction temperature is 65°C, and the pressure in the feed zone is 0.20 MPa.

4. A method for using the reactor as claimed in claim 1, characterized in that: The working liquid is a mixed solution of 2-ethylanthraquinone, 1,2,4-trimethylbenzene and tetrabutylurea; wherein the concentration of 2-ethylanthraquinone is 120 g / L, and the volume ratio of 1,2,4-trimethylbenzene to tetrabutylurea is 6:4; there are a total of 16 restraining bodies in the reaction zone, a mesh with an aperture of 60 μm is placed between the ten restraining bodies near the bottom, and each restraining body is filled with 20.0 mg of microspherical Pd / Al2O3 catalyst with a particle size of 75-200 μm, wherein the mass fraction of palladium is 1.50%; a mesh with an aperture of 100 μm is placed between the six restraining bodies near the top, and each restraining body is filled with 15.0 mg of microspherical Pd / Al2O3 catalyst with a particle size of 110-200 μm, wherein the mass fraction of palladium is 2.00%; the gas flow rate of the reaction process is controlled to be 2.5 L / min, the working liquid flow rate is 0.50 L / h, the reaction temperature is 60° C., and the pressure in the feed zone is 0.15 MPa.

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