Stirred tank reactors and their use in rubber hydrogenation, batch hydrogenation process for nitrile rubber

Abstract

This invention relates to the field of rubber hydrogenation, and discloses a stirred tank reactor and its application in rubber hydrogenation, as well as a batch hydrogenation method for nitrile rubber. The stirred tank reactor includes a cylindrical body and a stirrer and hollow finger-shaped baffles placed inside the body. The stirrer includes a hollow stirring shaft and a stirring paddle mounted on the shaft. A hydrogen inlet is located at the top of the hollow stirring shaft, and an annular gas distributor is located at the bottom. The hollow finger-shaped baffles include a hollow straight tube and at least two short, downward-sloping straight tubes arranged along the bottom of the tube. The bottom of the hollow straight tube is connected to a hydrogen inlet pipe at the bottom of the cylindrical body. The multiple hollow finger-shaped baffles within the stirred tank reactor enable good dispersion and mixing of hydrogen in the rubber solution, and, together with the hollow stirring shaft and gas distributor, achieve a top-to-bottom self-circulation of hydrogen in the gas phase space within the reactor, thereby improving the hydrogenation efficiency of the rubber hydrogenation reaction.

Description

Technical Field

[0001] This invention relates to the field of rubber hydrogenation, specifically to a stirred tank reactor and its application in rubber hydrogenation, and a batch hydrogenation method for nitrile rubber. Background Technology

[0002] Nitrile butadiene rubber (NBR) is a copolymer obtained by polymerizing butadiene and acrylonitrile monomers. Due to its excellent oil resistance, benzene resistance, heat resistance, and physical and mechanical properties, it has become the standard elastomer for oil-resistant rubber products. However, because its molecular chain contains a large number of unsaturated carbon-carbon double bonds, its heat resistance is relatively poor. Selective hydrogenation of these unsaturated carbon-carbon double bonds can produce highly saturated NBR, also known as hydrogenated NBR. Hydrogenated NBR not only inherits the oil resistance, abrasion resistance, and low-temperature resistance (-40℃) of NBR, but also possesses superior heat resistance (150℃), oxidation resistance, ozone resistance, and chemical resistance, and is widely used in automobile manufacturing, machining, metallurgical sealing, and the petroleum industry.

[0003] Methods for hydrogenating the unsaturated carbon-carbon double bonds in nitrile rubber typically include acrylonitrile-ethylene copolymerization, emulsion hydrogenation, and solution hydrogenation, with solution hydrogenation being the primary method used industrially both domestically and internationally. In solution hydrogenation, the nitrile rubber is first pulverized and dissolved in a suitable solvent, then hydrogenated in a high-temperature, high-pressure reactor. The selected hydrogenation catalyst selectively hydrogenates only the double bonds, without hydrogenating the nitrile group (-C≡N) in the acrylonitrile unit. This solution hydrogenation method typically uses a batch reactor, operates intermittently, requires high temperature and pressure, and has a long reaction time.

[0004] In order to increase the gas-liquid two-phase contact area between hydrogen and nitrile rubber solution and reduce the hydrogenation reaction conditions, the type and structure of hydrogenation reactors in the existing technology need to be optimized and improved.

[0005] CN101081878A discloses a method for hydrogenating nitrile rubber using a rotating disc reactor. The rotating disc reactor includes a support component assembled to rotate about an axis, the support component having a surface on which one or more reactants, particularly nitrile rubber, can be supplied. It also includes a feeding device for supplying nitrile rubber to the surface of the support component, and a feeding device for supplying hydrogen and optionally a catalyst and a co-catalyst into the reactor. Using this rotating disc reactor, near 100% hydrogenation degree can be obtained in 6 hours under conditions of 1.0-3.0 MPa.G and 110-160°C. However, the rotating disc hydrogenation reactor has a complex structure and is difficult to manufacture.

[0006] CN104190340A discloses a process for preparing hydrogenated nitrile butadiene rubber using a microtube reactor. This microtube reactor consists of a preheating module and a reaction module, facilitating installation and disassembly. The hydrogenated nitrile butadiene rubber product prepared using this microtube reactor has a hydrogenation degree of over 96%, reducing catalyst consumption by more than 15% compared to a batch reactor, and shortening the reaction time by at least 30 times, significantly reducing energy consumption and production costs. Furthermore, it allows for convenient continuous production of hydrogenated nitrile butadiene rubber. However, the operation and control of this microtube hydrogenation reactor are relatively complex.

[0007] In the existing technology, although the optimized new hydrogenation reactor enhances the dispersion of hydrogen in nitrile rubber solution and increases the contact area between the gas and liquid phases, it places higher demands on the operation and control of the hydrogenation process. Summary of the Invention

[0008] The purpose of this invention is to overcome the problems of limited contact area between hydrogen and rubber solution in the existing technology of rubber hydrogenation, complex reactor structure and cumbersome process, and low hydrogenation efficiency of rubber. This invention provides a stirred tank reactor and its application in rubber hydrogenation, as well as a batch hydrogenation method for nitrile rubber. The stirred tank reactor is equipped with multiple hollow finger-shaped baffles, which can achieve good dispersion and mixing of hydrogen in the rubber solution. Together with a hollow stirring shaft and gas distributor, it enables the hydrogen in the gas phase space of the stirred tank reactor to self-circulate from top to bottom, thereby improving the hydrogenation efficiency of the rubber hydrogenation reaction.

[0009] To achieve the above objectives, the first aspect of the present invention provides a stirred tank reactor, characterized in that the stirred tank reactor includes a cylindrical body 1 and a stirrer and a hollow finger-shaped baffle 2 disposed within the cylindrical body, the stirrer includes a hollow stirring shaft 3 and a stirring paddle 5 mounted on the hollow stirring shaft 3, the upper part of the hollow stirring shaft 3 is provided with a hydrogen inlet 7; the bottom of the hollow stirring shaft 3 is provided with an annular gas distributor 4;

[0010] The hollow finger-shaped baffle 2 includes a hollow straight tube 21 and at least two short straight tubes 22 that are obliquely downward along the upward direction from the bottom end of the hollow straight tube 21.

[0011] The bottom of the hollow straight tube 21 is connected to the hydrogen feed pipe 6 at the bottom of the cylinder 1.

[0012] A second aspect of the present invention provides an application of the above-described stirred tank reactor in the hydrogenation of rubber.

[0013] A third aspect of the present invention provides a method for intermittent hydrogenation of nitrile rubber, characterized in that, in the above-mentioned stirred tank reactor, a homogeneous intermittent hydrogenation reaction is carried out on the nitrile rubber solution in the presence of a hydrogenation catalyst.

[0014] Through the above technical solutions, the stirred tank reactor and its application in rubber hydrogenation, and the intermittent hydrogenation method for nitrile rubber provided by the present invention achieve the following beneficial effects:

[0015] The stirred tank reactor provided by this invention is equipped with multiple hollow finger-shaped baffles, which enable good dispersion and mixing of hydrogen gas that has just entered the reactor in the rubber solution. Furthermore, the hollow stirring shaft and gas distributor enable the hydrogen gas in the gas phase space within the stirred tank reactor to achieve self-circulation from top to bottom, thereby improving the hydrogenation efficiency of the rubber hydrogenation reaction.

[0016] Furthermore, the stirred tank reactor described in this invention is used in the intermittent hydrogenation reaction of nitrile rubber. During the reaction, continuously replenished hydrogen gas enters the stirred tank reactor from the bottom through a short, straight pipe angled downwards on a hollow finger-shaped baffle. The hydrogen gas exiting from the short pipe collides violently with the nitrile rubber solution ejected by the stirring paddle, breaking the hydrogen gas flow into fine bubbles and dispersing them in the nitrile rubber solution. Simultaneously, under the rapid rotation of the hollow stirring shaft, hydrogen gas in the gas phase space of the stirred tank reactor is drawn into the hollow stirring shaft. The drawn-in hydrogen gas is then ejected from the openings in the annular gas distributor at the bottom and also dispersed in the nitrile rubber solution. Under the combined action of the finger-shaped baffle, the hollow stirring shaft, and the gas distributor, the hydrogen gas and the nitrile rubber solution achieve sufficient contact, increasing the gas-liquid mass transfer area and improving the hydrogenation efficiency of nitrile rubber.

[0017] Furthermore, the intermittent hydrogenation method for nitrile rubber provided by this invention is easy to operate and can be stably controlled. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of one embodiment of the stirred tank reactor described in this invention;

[0019] Figure 2 This is a top view of the annular gas distributor described in this invention.

[0020] Explanation of reference numerals in the attached figures

[0021] 1. Stirred reactor shell; 2. Hollow finger-shaped baffle; 21. Hollow straight pipe; 22. Short straight pipe; 221. First short straight pipe; 222. Second short straight pipe; 3. Hollow stirring shaft; 4. Annular gas distributor; 41. Connecting pipe between gas distributor and hollow stirring shaft; 42. Opening on gas distributor; 5. Stirring paddle; 6. Hydrogen feed pipe; 7. Hydrogen inlet; 8. Rubber solution inlet; 9. Hydrogenation catalyst inlet; 10. Hydrogenated rubber solution outlet; 11. Temperature control jacket; 12. Jacket medium outlet; 13. Jacket medium inlet. Detailed Implementation

[0022] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0023] The first aspect of the present invention provides a stirred tank reactor, characterized in that the stirred tank reactor includes a cylindrical body 1 and a stirrer and a hollow finger-shaped baffle 2 placed inside the cylindrical body, the stirrer includes a hollow stirring shaft 3 and a stirring paddle 5 installed on the hollow stirring shaft 3, the upper part of the hollow stirring shaft 3 is provided with a hydrogen inlet 7; the bottom of the hollow stirring shaft 3 is provided with an annular gas distributor 4.

[0024] The hollow finger-shaped baffle 2 includes a hollow straight tube 21 and at least two short straight tubes 22 that are obliquely downward along the upward direction from the bottom end of the hollow straight tube 21.

[0025] The bottom of the hollow straight tube 21 is connected to the hydrogen feed pipe 6 at the bottom of the cylinder 1.

[0026] The stirred tank reactor provided by this invention is equipped with multiple hollow finger-shaped baffles, which enable good dispersion and mixing of hydrogen gas that has just entered the reactor in the rubber solution. Furthermore, the hollow stirring shaft and gas distributor enable the hydrogen gas in the gas phase space within the stirred tank reactor to achieve self-circulation from top to bottom, thereby improving the hydrogenation efficiency of the rubber hydrogenation reaction.

[0027] In this invention, the hollow straight tube 21 is a hollow straight tube with its top and bottom sealed.

[0028] According to the present invention, the diameter D2 of the hollow straight tube 21 is 1 / 20 to 1 / 4 times the diameter D1 of the cylinder 1, preferably 1 / 10 to 1 / 5 times.

[0029] According to the present invention, the distance d1 between the bottom end of the hollow straight tube 21 and the bottommost end of the inner wall of the cylinder 1 is 1 / 7 to 1 / 2 times the diameter D1 of the cylinder 1, preferably 1 / 5 to 1 / 3 times.

[0030] According to the present invention, the height H2 of the hollow straight tube 21 is 2 / 5-9 / 10 times the height H1 of the straight section of the cylinder 1, preferably 3 / 5-17 / 20 times.

[0031] According to the present invention, the distance d2 between the axis of the hollow straight tube 21 and the inner wall of the straight section of the cylinder 1 is 17 / 10-2 times the diameter D2 of the hollow straight tube 21, preferably 1-1.5 times.

[0032] According to the present invention, the at least two downwardly angled short straight pipes 22 are arranged in parallel.

[0033] According to the present invention, the diameter D3 of the short straight tube 22 is 1 / 4 to 1, preferably 1 / 3 to 7 / 10 times the diameter D2 of the hollow straight tube 21.

[0034] According to the present invention, the length L of the short straight tube 22 is 1-5 times the diameter D3 of the short straight tube 22, preferably 2-3.5 times.

[0035] According to the present invention, the included angle α between the axis of the short straight tube 22 and the axis of the hollow straight tube 21 is 10-60°, preferably 30-50°.

[0036] According to the present invention, the short straight pipe 22 is a straight pipe with a sealed bottom and an opening in the pipe wall.

[0037] According to the present invention, the number of openings in the pipe wall of the short straight pipe 22 is 2-8, preferably 3-5;

[0038] According to the present invention, the diameter φ1 of the hole in the wall of the short straight pipe 22 is 0.5-5mm, preferably 2-3mm.

[0039] In this invention, the end of the short straight tube 22 points towards the axis of the hollow stirring shaft 3. Specifically, the axis of the short straight tube 22 intersects the axis of the hollow stirring shaft 3.

[0040] According to the present invention, a first short straight tube 221 and a second short straight tube 222 are arranged obliquely downward in the direction upward from the bottom end of the hollow straight tube 21.

[0041] According to the present invention, the distance d3 between the first short straight tube 221 and the bottom end of the hollow straight tube 21 is 1.5-4 times the diameter D2 of the hollow straight tube 21, preferably 2-3 times.

[0042] According to the present invention, the distance d4 between the axis of the first short straight tube 221 and the axis of the second short straight tube 222 is 1 / 3 to 3 / 2 times the diameter D2 of the hollow straight tube 21, preferably 2 / 3 to 6 / 5 times.

[0043] According to the present invention, the number of hollow finger-shaped baffles 2 is 2-8, preferably 4-6.

[0044] According to the present invention, the hollow finger-shaped baffles 2 are uniformly distributed along the inner circumference of the cylinder 1.

[0045] According to the present invention, the cylinder 1 further includes a hydrogen inlet 7, which is located above the material operating liquid surface of the hollow stirring shaft 3.

[0046] According to the present invention, the annular gas distributor 4 is used for hydrogen discharge.

[0047] According to the present invention, the annular gas distributor 4 and the hollow stirring shaft 3 are integrally formed.

[0048] According to the present invention, the annular diameter D4 of the annular gas distributor 4 is 1 / 2 to 9 / 10 of the diameter D1 of the cylinder 1, preferably 3 / 5 to 4 / 5.

[0049] In this invention, the ring diameter D4 refers to the average value of the sum of the outer ring diameter and the inner ring diameter of the annular gas distributor.

[0050] According to the present invention, the distance d5 between the center of the annular gas distributor 4 and the bottommost part of the inner cavity of the cylinder 1 is 1 / 15-1 / 3 of the diameter D1 of the cylinder 1, preferably 1 / 12-1 / 4.

[0051] According to the present invention, the annular gas distributor 4 is provided with an opening 42.

[0052] In this invention, the openings 42 are uniformly distributed on the annular gas distributor.

[0053] According to the present invention, the number of openings 42 on the annular gas distributor 4 is 4-30, preferably 8-20.

[0054] According to the present invention, the aperture φ2 of the opening 42 on the annular gas distributor 4 is 1-5 mm, preferably 2-3 mm.

[0055] In one specific embodiment of the present invention, such as Figure 2 The top view of the annular gas distributor 4 shown is as follows: Figure 2 As shown, the annular gas distributor 4 and the hollow stirring shaft 3 are integrally formed. The annular gas distributor 4 and the hollow stirring shaft 3 are connected by a connecting pipe 41. Openings 42 are evenly provided on the annular gas distributor 4.

[0056] According to the present invention, the number of the stirring paddles 5 is 1-6, preferably 2-4.

[0057] According to the present invention, the distance d6 between the plurality of stirring paddles 5 is 1 / 6 to 1 times the diameter D1 of the cylinder 1, preferably 1 / 3 to 2 / 3 times.

[0058] According to the present invention, the stirring paddle 5 includes at least one radial flow stirring paddle, and the radial flow stirring paddle is close to the annular gas distributor 4.

[0059] In one specific embodiment of the present invention, the stirring paddle 5 includes a radial flow stirring paddle, which is close to the annular gas distributor 4, and the other stirring paddles along the hollow stirring shaft 3 upward are conventional axial flow stirring paddles in the art.

[0060] According to the present invention, the diameter D5 of the stirring paddle 5 is 1 / 4 to 2 / 3 of the diameter D1 of the cylinder 1, preferably 1 / 3 to 1 / 2.

[0061] According to the present invention, the distance d7 between the stirring paddle 5 and the annular gas distributor 4 near the annular gas distributor 4 is 1 / 12 to 1 / 2 times the diameter D1 of the cylinder 1, preferably 1 / 6 to 1 / 3 times.

[0062] According to the present invention, the stirred tank reactor further includes a temperature control jacket 11, a rubber solution inlet 8, a hydrogenation catalyst inlet 9, and a hydrogenated rubber solution outlet 10;

[0063] The temperature control jacket 11 is located outside the cylinder 1; the rubber solution inlet 8 and the hydrogenation catalyst inlet 9 are located at the top of the cylinder 1; and the hydrogenated rubber solution outlet is located at the bottom of the cylinder 1.

[0064] In this invention, the reaction temperature in the stirred tank reactor is controlled by introducing a medium into the temperature control jacket 11. Specifically, the medium enters the temperature control jacket 11 through the jacket medium inlet 13 and is discharged through the jacket medium outlet 12.

[0065] According to the present invention, the Reynolds number of the fluid flowing in the stirred reactor is 1000-5000, preferably 2000-3000.

[0066] A second aspect of the present invention provides an application of the above-mentioned stirred tank reactor in the hydrogenation of nitrile rubber.

[0067] A third aspect of the present invention provides a method for intermittent hydrogenation of nitrile rubber, characterized in that, in the above-mentioned stirred tank reactor, a homogeneous intermittent hydrogenation reaction is carried out on the nitrile rubber solution in the presence of a hydrogenation catalyst.

[0068] According to the present invention, the solvent in the nitrile rubber solution is selected from at least one of chlorobenzene, bromobenzene, toluene, xylene, acetone and butanone, preferably at least one of chlorobenzene, bromobenzene and butanone.

[0069] According to the present invention, the mass concentration of nitrile rubber in the nitrile rubber solution is 5-12 wt%, preferably 7-10 wt%.

[0070] According to the present invention, the hydrogenation catalyst is selected from at least one of rhodium-based hydrogenation catalysts, ruthenium-based hydrogenation catalysts, palladium-based hydrogenation catalysts and rhodium-ruthenium-based hydrogenation catalysts, preferably rhodium-based hydrogenation catalysts and / or rhodium-ruthenium-based rhodium-based hydrogenation catalysts.

[0071] According to the present invention, the amount of the hydrogenation catalyst is 0.05-0.2 wt%, preferably 0.08-0.15 wt%, based on the mass of dry nitrile rubber.

[0072] According to the present invention, the conditions for the homogeneous intermittent hydrogenation reaction include: an operating pressure of 4-8 MPa.G, preferably 5-7 MPa.G; an operating temperature of 80-140°C, preferably 100-120°C; and a total hydrogenation reaction time of 5-10 h, preferably 6-8 h.

[0073] The present invention will be described in detail below through embodiments.

[0074] In the following examples and comparative examples, the degree of hydrogenation was determined using the bromine-iodine method.

[0075] In the following examples and comparative examples, the solvent in the nitrile rubber solution is chlorobenzene; the catalyst is triphenylphosphine-rhodium chloride; the volume of the stirred tank reactor is 50L, its inner diameter is 350mm, and the length-to-diameter ratio of the straight section is 1.5:1.

[0076] Example 1

[0077] Four hollow finger-shaped baffles 2 are installed inside the stirred tank reactor and are evenly distributed along the circumference. Each hollow finger-shaped baffle 2 includes a hollow straight tube 21 and two parallel, downward-sloping short straight tubes 22 (first short straight tube 221 and second short straight tube 222) arranged sequentially upwards from the bottom end of the hollow straight tube 21. The diameter D2 of the hollow straight tube 21 is 1 / 10 times the diameter D1 of the stirred tank reactor body 1; the distance d1 between the bottom end of the hollow straight tube 21 and the bottommost point of the inner wall of the stirred tank reactor body 1 is 1 / 5 times the diameter D1 of the body 1; the height H2 of the hollow straight tube 21 is 3 / 4 times the height H1 of the straight section of the stirred tank reactor body 1; the axis of the hollow straight tube 21 is parallel to the axis of the stirred tank reactor body 1. The distance d2 between the inner walls of the straight sections of reactor cylinder 1 is 1.5 times the diameter D2 of the hollow straight tube 21; the diameter D3 of the short straight tube 22 is 7 / 10 times the diameter D2 of the hollow straight tube 21; the length L of the short straight tube 22 is 2 times the diameter D3 of the short straight tube 22; the angle α between the axis of the short straight tube 22 and the axis of the hollow straight tube 21 is 45°; the bottom end of the short straight tube 22 is sealed and has three openings with a diameter φ1 of 2mm; the distance d4 between the axis of the first short straight tube 221 and the axis of the second short straight tube 222 is 2 / 3 times the diameter D2 of the hollow straight tube 21.

[0078] The annular gas distributor at the bottom of the hollow stirring shaft has a diameter D4 that is 3 / 5 of the diameter D1 of the stirred tank reactor body 1. The annular gas distributor 4 has 16 openings 42 with a diameter φ2 of 2 mm. The distance d5 between the center of the annular gas distributor 4 and the bottom of the inner wall of the stirred tank reactor body 1 is 1 / 8 of the diameter D1 of the stirred tank reactor body 1. Along the hollow stirring shaft, upwards from the annular gas distributor, multiple stirring blades 5 are installed. A radial flow stirring blade—a six-bladed disc turbine—is installed at a distance d7 from the annular gas distributor 4, which is 1 / 6 of the diameter D1 of the stirred tank reactor body 1. An axial flow stirring blade—a four-bladed turbine—is installed upwards from the aforementioned radial flow stirring blade, at a distance d6 from it, which is 1 / 3 of the diameter D1 of the stirred tank reactor body 1. The diameter D5 of both stirring blades is 1 / 3 of the diameter D1 of the stirred tank reactor body 1. A temperature-controlled jacket 11 is installed outside the stirred tank reactor. Hot oil at 120°C is introduced through the jacket medium inlet 13 to provide the necessary heat for the hydrogenation reaction. The heat-exchanged medium is discharged from the jacket medium outlet 12.

[0079] Under normal temperature and pressure, nitrile rubber (NBR) is first prepared into an NBR solution using chlorobenzene as a solvent. The weight ratio of chlorobenzene to pure NBR is 93:7, and the mass concentration of the NBR solution is 7 wt%. The amount of hydrogenation catalyst used is 0.08 wt% based on the mass of the dry NBR. The uniformly prepared NBR solution is then added to a stirred tank reactor. After the NBR solution has been completely added, the stirrer is started to bring the Reynolds number of the fluid flow inside the stirred tank reactor to 3000. Under this condition, the catalyst is added to the stirred tank reactor. After the catalyst has been added, hot oil is circulated into the jacket of the stirred tank reactor to raise the reactor temperature to 120°C. Then, the automatic hydrogen feed valve at the bottom of the stirred tank reactor is opened to introduce hydrogen into the reactor until the reactor pressure reaches 5 MPa. The automatic hydrogen feed valve is then closed, and the hydrogenation reaction begins. During the reaction, the interlock between the remote pressure transmission of the stirred tank reactor and the bottom automatic hydrogen feed valve automatically opens and closes the hydrogen feed valve, so that the pressure inside the stirred tank reactor is always maintained at 5 MPa.G.

[0080] Samples were taken at 4, 6, 8 and 10 hours after the start of the hydrogenation reaction to determine the degree of hydrogenation of the unsaturated polymer. The results are listed in Table 1 below.

[0081] Example 2

[0082] The basic embodiment is repeated in Example 1, except that the distance d1 between the bottom end of the hollow straight tube 21 of the hollow finger-shaped baffle 2 and the bottom end of the inner wall of the stirred tank reactor cylinder 1 is 1 / 3 times the diameter D1 of the cylinder 1.

[0083] Samples were taken at 4, 6, 8 and 10 hours after the start of the hydrogenation reaction to determine the degree of hydrogenation of the unsaturated polymer. The results are listed in Table 1 below.

[0084] Example 3

[0085] The basic embodiment 1 is repeated, except that the diameter D3 of the short straight tube 22 is 1 / 3 times the diameter D2 of the hollow straight tube 21.

[0086] Samples were taken at 4, 6, 8 and 10 hours after the start of the hydrogenation reaction to determine the degree of hydrogenation of the unsaturated polymer. The results are listed in Table 1 below.

[0087] Example 4

[0088] The basic embodiment 1 is repeated, except that the length L of the short straight tube 22 is 3.5 times the diameter D1 of the hollow straight tube 21.

[0089] Samples were taken at 4, 6, 8 and 10 hours after the start of the hydrogenation reaction to determine the degree of hydrogenation of the unsaturated polymer. The results are listed in Table 1 below.

[0090] Example 5

[0091] The basic embodiment 1 is repeated, except that the bottom end of the short straight tube 22 is sealed and has an opening, the number of openings is 5, and the diameter of the opening φ1 is 2mm.

[0092] Samples were taken at 4, 6, 8 and 10 hours after the start of the hydrogenation reaction to determine the degree of hydrogenation of the unsaturated polymer. The results are listed in Table 1 below.

[0093] Example 6

[0094] The basic embodiment 1 is repeated, except that the distance d4 between the axes of the first short straight tube 221 and the second short straight tube 222 is 6 / 5 times the diameter D2 of the hollow straight tube 21.

[0095] Samples were taken at 4, 6, 8 and 10 hours after the start of the hydrogenation reaction to determine the degree of hydrogenation of the unsaturated polymer. The results are listed in Table 1 below.

[0096] Example 7

[0097] The basic embodiment is repeated in Example 1, except that the diameter D2 of the hollow straight tube 21 is 1 / 5 times the diameter D1 of the stirred tank reactor body 1.

[0098] Samples were taken at 4, 6, 8 and 10 hours after the start of the hydrogenation reaction to determine the degree of hydrogenation of the unsaturated polymer. The results are listed in Table 1 below.

[0099] Example 8

[0100] The basic example is repeated from Example 1, except that: in the nitrile rubber solution, the weight ratio of chlorobenzene to pure nitrile rubber is 90:10, that is, the mass concentration of the nitrile rubber solution is 10wt%, and the Reynolds number of the fluid flow inside the stirred tank reactor reaches 2000.

[0101] Samples were taken at 4, 6, 8 and 10 hours after the start of the hydrogenation reaction to determine the degree of hydrogenation of the unsaturated polymer. The results are listed in Table 1 below.

[0102] Example 9

[0103] The basic example 1 was repeated, except that the amount of hydrogenation catalyst used was 0.15 wt% based on the mass of dry nitrile rubber.

[0104] Samples were taken at 4, 6, 8 and 10 hours after the start of the hydrogenation reaction to determine the degree of hydrogenation of the unsaturated polymer. The results are listed in Table 1 below.

[0105] Example 10

[0106] The basic example is repeated from Example 1, except that the pressure inside the stirred tank reactor is always maintained at 7 MPa.G.

[0107] Samples were taken at 4, 6, 8 and 10 hours after the start of the hydrogenation reaction to determine the degree of hydrogenation of the unsaturated polymer. The results are listed in Table 1 below.

[0108] Example 11

[0109] The basic embodiment 1 is repeated, except that three short straight tubes 22 are arranged obliquely downward along the upward direction from the bottom end of the hollow straight tube 21.

[0110] Samples were taken at 4, 6, 8 and 10 hours after the start of the hydrogenation reaction to determine the degree of hydrogenation of the unsaturated polymer. The results are listed in Table 1 below.

[0111] Example 12

[0112] The basic embodiment 1 is repeated, except that the angle α between the axis of the short straight tube 22 and the axis of the hollow straight tube 21 is 20°.

[0113] Samples were taken at 4, 6, 8 and 10 hours after the start of the hydrogenation reaction to determine the degree of hydrogenation of the unsaturated polymer. The results are listed in Table 1 below.

[0114] Example 13

[0115] The basic embodiment 1 is repeated, except that the number of hollow finger-shaped baffles 2 is 2.

[0116] Samples were taken at 4, 6, 8 and 10 hours after the start of the hydrogenation reaction to determine the degree of hydrogenation of the unsaturated polymer. The results are listed in Table 1 below.

[0117] Example 14

[0118] The basic embodiment 1 is repeated, except that the annular diameter D4 of the annular gas distributor 4 is half the diameter D1 of the cylinder 1.

[0119] Samples were taken at 4, 6, 8 and 10 hours after the start of the hydrogenation reaction to determine the degree of hydrogenation of the unsaturated polymer. The results are listed in Table 1 below.

[0120] Comparative Example 1

[0121] The basic embodiment 1 is repeated, except that the hollow finger-shaped baffle 2 is replaced with a solid finger-shaped baffle.

[0122] Samples were taken at 4, 6, 8 and 10 hours after the start of the hydrogenation reaction to determine the degree of hydrogenation of the unsaturated polymer. The results are listed in Table 1 below.

[0123] Comparative Example 2

[0124] The basic embodiment 1 is repeated, except that the hollow finger-shaped baffle 2 is replaced with a solid plate-shaped baffle, which is conventional in the art.

[0125] Samples were taken at 4, 6, 8 and 10 hours after the start of the hydrogenation reaction to determine the degree of hydrogenation of the unsaturated polymer. The results are listed in Table 1 below.

[0126] Comparative Example 3

[0127] The basic embodiment 1 is repeated, except that a short straight tube 22 is provided at an angle downward along the upward direction from the bottom end of the hollow straight tube 21.

[0128] Samples were taken at 4, 6, 8 and 10 hours after the start of the hydrogenation reaction to determine the degree of hydrogenation of the unsaturated polymer. The results are listed in Table 1 below.

[0129] Table 1

[0130]

[0131]

[0132] As can be seen from the data listed in Table 1, according to the present invention, by utilizing the hollow finger-shaped baffle, hollow stirring shaft and gas distributor installed in the stirred tank reactor, the continuous replenishment of hydrogen gas during the hydrogenation reaction and the full contact, dispersion and mixing of hydrogen gas in the gas phase space of the reactor with the nitrile rubber solution are realized, thereby improving the hydrogenation efficiency of the unsaturated polymer.

[0133] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for intermittent hydrogenation of nitrile rubber, characterized in that, In a stirred tank reactor, a homogeneous batch hydrogenation reaction of nitrile rubber solution is carried out in the presence of a hydrogenation catalyst. During the reaction, continuously replenished hydrogen enters the stirred tank reactor from the bottom through a short, straight tube angled downwards on a hollow finger-shaped baffle. The hydrogen exiting from the short tube collides violently with the nitrile rubber solution thrown out by the agitator, breaking the hydrogen gas flow into tiny bubbles and dispersing them in the nitrile rubber solution. Simultaneously, under the rapid rotation of the hollow agitator shaft, hydrogen in the gas phase space of the stirred tank reactor is drawn into the hollow agitator shaft. The drawn-in hydrogen is then thrown out through the openings on the bottom annular gas distributor and also dispersed in the nitrile rubber solution. The stirred tank reactor includes a cylindrical body (1) and a stirrer and a hollow finger-shaped baffle (2) placed inside the cylindrical body. The stirrer includes a hollow stirring shaft (3) and a stirring paddle (5) installed on the hollow stirring shaft (3). The upper part of the hollow stirring shaft (3) is provided with a hydrogen inlet (7); the bottom of the hollow stirring shaft (3) is provided with an annular gas distributor (4). The hollow finger-shaped baffle (2) includes a hollow straight tube (21) and at least two short straight tubes (22) that are obliquely downward along the direction of the bottom end of the hollow straight tube (21). The bottom of the hollow straight tube (21) is connected to the hydrogen feed pipe (6) at the bottom of the cylinder (1); The angle α between the axis of the short straight tube (22) and the axis of the hollow straight tube (21) is 30-50°; The short straight pipe (22) includes a first short straight pipe (221) and a second short straight pipe (222); Along the direction upward from the bottom end of the hollow straight tube (21), a first short straight tube (221) and a second short straight tube (222) are arranged obliquely downward in sequence. The distance d3 between the bottom end of the first short straight tube (221) and the hollow straight tube (21) is 1.5-4 times the diameter D2 of the hollow straight tube (21); The mass concentration of nitrile rubber in the nitrile rubber solution is 7-10 wt%.

2. The intermittent hydrogenation method according to claim 1, wherein, The diameter D2 of the hollow straight tube (21) is 1 / 20 to 1 / 4 times the diameter D1 of the cylinder (1).

3. The intermittent hydrogenation method according to claim 1, wherein, The diameter D2 of the hollow straight tube (21) is 1 / 10 to 1 / 5 times the diameter D1 of the cylinder (1).

4. The intermittent hydrogenation method according to any one of claims 1-3, wherein, The distance d1 between the bottom end of the hollow straight tube (21) and the bottom end of the inner wall of the cylinder (1) is 1 / 7 to 1 / 2 times the diameter D1 of the cylinder (1).

5. The intermittent hydrogenation method according to claim 4, wherein, The distance d1 between the bottom end of the hollow straight tube (21) and the bottom end of the inner wall of the cylinder (1) is 1 / 5 to 1 / 3 times the diameter D1 of the cylinder (1).

6. The intermittent hydrogenation method according to any one of claims 1-3, wherein, The height H2 of the hollow straight tube (21) is 2 / 5 to 9 / 10 times the height H1 of the straight section of the cylinder (1).

7. The intermittent hydrogenation method according to claim 6, wherein, The height H2 of the hollow straight tube (21) is 3 / 5 to 17 / 20 times the height H1 of the straight section of the cylinder (1).

8. The intermittent hydrogenation method according to any one of claims 1-3, wherein, The distance d2 between the axis of the hollow straight tube (21) and the inner wall of the straight section of the cylinder (1) is 17 / 10-2 times the diameter D2 of the hollow straight tube (21).

9. The intermittent hydrogenation method according to claim 8, wherein, The distance d2 between the axis of the hollow straight tube (21) and the inner wall of the straight section of the cylinder (1) is 1-1.5 times the diameter D2 of the hollow straight tube (21).

10. The intermittent hydrogenation method according to any one of claims 1-3, wherein, The at least two downward-sloping short straight pipes (22) are arranged in parallel; And / or, the diameter D3 of the short straight tube (22) is 1 / 4-1 of the diameter D2 of the hollow straight tube (21); And / or, the length L of the short straight tube (22) is 1-5 times the diameter D3 of the short straight tube (22).

11. The intermittent hydrogenation method according to claim 10, wherein, The diameter D3 of the short straight tube (22) is 1 / 3 to 7 / 10 times the diameter D2 of the hollow straight tube (21); And / or, the length L of the short straight tube (22) is 2-3.5 times the diameter D3 of the short straight tube (22).

12. The intermittent hydrogenation method according to any one of claims 1-3, wherein, The short straight pipe (22) is a straight pipe with a closed bottom and an opening; And / or, the number of openings in the short straight tube (22) is 2-8; And / or, the aperture φ1 of the opening of the short straight tube (22) is 0.5-5mm.

13. The intermittent hydrogenation method according to claim 12, wherein, The short straight tube (22) has 3-5 openings; And / or, the aperture φ1 of the opening of the short straight tube (22) is 2-3 mm.

14. The intermittent hydrogenation method according to any one of claims 1-3, wherein, The axis of the short straight tube (22) intersects the axis of the hollow stirring shaft (3).

15. The intermittent hydrogenation method according to any one of claims 1-3, wherein, The distance d3 between the bottom end of the first short straight tube (221) and the hollow straight tube (21) is 2-3 times the diameter D2 of the hollow straight tube (21); And / or, the distance d4 between the axis of the first short straight tube (221) and the axis of the second short straight tube (222) is 1 / 3 to 3 / 2 times the diameter D2 of the hollow straight tube (21).

16. The intermittent hydrogenation method according to claim 15, wherein, The distance d4 between the axis of the first short straight tube (221) and the axis of the second short straight tube (222) is 2 / 3 to 6 / 5 times the diameter D2 of the hollow straight tube (21).

17. The intermittent hydrogenation method according to any one of claims 1-3, wherein, The number of hollow finger-shaped baffles (2) is 2-8; And / or, the hollow finger-shaped baffles (2) are evenly distributed along the inner circumference of the cylinder (1).

18. The intermittent hydrogenation method according to claim 17, wherein, The number of hollow finger-shaped baffles (2) is 4-6.

19. The intermittent hydrogenation method according to any one of claims 1-3, wherein, The cylinder (1) also includes a hydrogen inlet (7), which is located above the material operating liquid surface of the hollow stirring shaft (3). And / or, the annular gas distributor (4) is used for hydrogen discharge.

20. The intermittent hydrogenation method according to any one of claims 1-3, wherein, The annular gas distributor (4) and the hollow stirring shaft (3) are integrally formed; And / or, the annular diameter D4 of the annular gas distributor (4) is 1 / 2 to 9 / 10 of the diameter D1 of the cylinder (1); And / or, the distance d5 between the center of the annular gas distributor (4) and the bottom of the interior of the cylinder (1) is 1 / 15 to 1 / 3 of the diameter D1 of the cylinder (1).

21. The intermittent hydrogenation method according to any one of claims 1-3, wherein, The annular gas distributor (4) has an annular diameter D4 that is 3 / 5 to 4 / 5 of the diameter D1 of the cylinder (1); And / or, the distance d5 between the center of the annular gas distributor (4) and the bottom of the interior of the cylinder (1) is 1 / 12 to 1 / 4 of the diameter D1 of the cylinder (1).

22. The intermittent hydrogenation method according to any one of claims 1-3, wherein, The annular gas distributor (4) is provided with an opening (42).

23. The intermittent hydrogenation method according to claim 22, wherein, The number of openings on the annular gas distributor (4) is 4-30; And / or, the aperture φ2 of the annular gas distributor (4) is 1-5 mm.

24. The intermittent hydrogenation method according to claim 23, wherein, The number of openings on the annular gas distributor (4) is 8-20; And / or, the aperture φ2 of the annular gas distributor (4) is 2-3 mm.

25. The intermittent hydrogenation method according to any one of claims 1-3, wherein, The number of the stirring paddles (5) is 1-6; And / or, the distance d6 between the plurality of said stirring paddles (5) is 1 / 6 to 1 times the diameter D1 of said cylinder (1); And / or, the stirring paddle (5) includes at least one radial flow stirring paddle, and the radial flow stirring paddle is close to the annular gas distributor (4).

26. The intermittent hydrogenation method according to claim 25, wherein, The number of the stirring paddles (5) is 2-4; And / or, the distance d6 between the plurality of said stirring paddles (5) is 1 / 3 to 2 / 3 times the diameter D1 of said cylinder (1).

27. The intermittent hydrogenation method according to any one of claims 1-3, wherein, The diameter D5 of the stirring paddle (5) is 1 / 4 to 2 / 3 of the diameter D1 of the cylinder (1); And / or, the distance d7 between the agitator (5) near the annular gas distributor (4) and the annular gas distributor (4) is 1 / 12 to 1 / 2 times the diameter D1 of the cylinder (1).

28. The intermittent hydrogenation method according to any one of claims 1-3, wherein, The diameter D5 of the stirring paddle (5) is 1 / 3 to 1 / 2 of the diameter D1 of the cylinder (1); And / or, the distance d7 between the stirring paddle (5) near the annular gas distributor (4) and the annular gas distributor (4) is 1 / 6 to 1 / 3 times the diameter D1 of the cylinder (1).

29. The intermittent hydrogenation method according to any one of claims 1-3, wherein, The stirred tank reactor also includes a temperature control jacket (11), a rubber solution inlet (8), a hydrogenation catalyst inlet (9), and a hydrogenated rubber solution outlet (10). The temperature control jacket (11) is located outside the cylinder (1); the rubber solution inlet (8) and the hydrogenation catalyst inlet (9) are located at the top of the cylinder (1); and the hydrogenated rubber solution outlet is located at the bottom of the cylinder (1).

30. The intermittent hydrogenation method according to any one of claims 1-3, wherein, The Reynolds number for fluid flow in the stirred tank reactor is 1000-5000.

31. The intermittent hydrogenation method according to claim 30, wherein, The Reynolds number of the fluid flowing inside the stirred tank reactor is 2000-3000.

32. The intermittent hydrogenation method according to claim 31, wherein, The solvent in the nitrile rubber solution is selected from at least one of chlorobenzene, bromobenzene, toluene, xylene, acetone, and butanone.

33. The intermittent hydrogenation method according to claim 32, wherein, The solvent in the nitrile rubber solution is selected from at least one of chlorobenzene, bromobenzene, and butanone.

34. The intermittent hydrogenation method according to any one of claims 1, 32, and 33, wherein, The hydrogenation catalyst is selected from at least one of rhodium-based hydrogenation catalysts, ruthenium-based hydrogenation catalysts, palladium-based hydrogenation catalysts, and rhodium-ruthenium-based hydrogenation catalysts; And / or, based on the mass of dry nitrile rubber, the amount of the hydrogenation catalyst is 0.05-0.2 wt%.

35. The intermittent hydrogenation method according to claim 34, wherein, The hydrogenation catalyst is selected from rhodium-based hydrogenation catalysts and / or rhodium-ruthenium-based rhodium-based hydrogenation catalysts; And / or, based on the mass of dry nitrile rubber, the amount of the hydrogenation catalyst is 0.08-0.15 wt%.

36. The intermittent hydrogenation method according to any one of claims 1, 32, and 33, wherein, The conditions for the homogeneous intermittent hydrogenation reaction include: an operating pressure of 4-8 MPa.G; an operating temperature of 80-140℃; and a total hydrogenation reaction time of 5-10 h.

37. The intermittent hydrogenation method according to claim 36, wherein, The conditions for the homogeneous intermittent hydrogenation reaction include: an operating pressure of 5-7 MPa.G; an operating temperature of 100-120℃; and a total hydrogenation reaction time of 6-8 h.

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