System for preparing dimethyl 1, 4-cyclohexanedicarboxylate

Abstract

The utility model provides a system for preparing 1, 4-cyclohexanedicarboxylic acid dimethyl ester. The system comprises a first feeding pipeline, a second feeding pipeline and a hydrogenation reactor, the first feeding pipeline is communicated with the hydrogenation reactor through the bottom of the hydrogenation reactor; a reinforced mass transfer device is arranged in the hydrogenation reactor, microbubble outlets are formed in the upper end and the lower end of the reinforced mass transfer device, and the number of the microbubble outlets in the upper end is smaller than that of the microbubble outlets in the lower end; the second feeding pipeline is connected with the enhanced mass transfer device; the hydrogenation reactor is a slurry bed reactor, a material outlet of the hydrogenation reactor is higher than the reinforced mass transfer device in the vertical direction, and the material outlet is lower than the liquid level in the hydrogenation reactor in the vertical direction; a baffle is arranged in the hydrogenation reactor close to the material outlet, and the top of the baffle is located between the material outlet and the liquid level of the hydrogenation reactor in the vertical direction; the bottoms of the baffles are obliquely arranged close to the side wall of the hydrogenation reactor. The system can effectively increase the phase boundary mass transfer area of the gas phase and the liquid phase.

Description

TECHNICAL FIELD

[0001] The utility model relates to 1,4 -cyclohexane dimethyl dicarboxylate preparation technical field, specifically, relate to a system for preparing 1,4 -cyclohexane dimethyl dicarboxylate. BACKGROUND

[0002] 1,4 -cyclohexane dimethyl dicarboxylate is an important chemical intermediate, can be used as the raw material of polyester resin, is used in the production high -performance fiber, film and engineering plastics. It is also the intermediate product of preparation 1,4 -cyclohexane dimethyl alcohol, 1,4 -cyclohexane dimethyl alcohol has very high application value, and is also the excellent monomer of production high -value -added polyester material. In the coating and resin industry, 1,4 -cyclohexane dimethyl dicarboxylate as modifier and solvent, can enhance the adhesion of coating, weather resistance and gloss, is widely used in building coating, automobile coating, wood coating and other fields. In addition, 1,4 -cyclohexane dimethyl dicarboxylate also plays a key role in resin production, can improve the toughness and chemical resistance of resin, is suitable for the production of plastic modification, adhesive, sealant and other products. 1,4 -cyclohexane dimethyl dicarboxylate can also be used as the intermediate of synthetic perfume, is used to manufacture various flower fragrance, fruit fragrance, wood fragrance and other types of essence. These essences are widely used in daily chemicals, food, cosmetics and other fields, provide rich aroma selection for consumers.

[0003] 1,4 -cyclohexane dimethyl dicarboxylate is mainly prepared by the hydrogenation of terephthalic acid dimethyl ester, the hydrogen gas in the existing hydrogenation reactor is distributed by the bottom distributor to complete the initial distribution and then enters the reactor, the bubble diameter is large, the phase boundary area of gas-liquid two phases is small, and the initial distribution bubble is easy to coalesce and become large in the rising process, which leads to low gas-liquid mass transfer efficiency and reaction rate.

[0004] Therefore, the utility model is provided. UTILITY MODEL CONTENT

[0005] The first purpose of the utility model is to provide a system for preparing 1,4 -cyclohexane dimethyl dicarboxylate, which adopts a slurry bed reactor for hydrogenation reaction and sets a mass transfer intensifier in the hydrogenation reactor, so that the gas-liquid two-phase phase boundary mass transfer area can be effectively increased, thereby helping to increase the gas-liquid mass transfer efficiency and reaction rate.

[0006] The second purpose of the utility model is to provide a method for preparing 1,4 -cyclohexane dimethyl dicarboxylate, which uses the above system to prepare 1,4 -cyclohexane dimethyl dicarboxylate, has high preparation efficiency and can realize efficient production of 1,4 -cyclohexane dimethyl dicarboxylate.

[0007] In order to achieve the above purposes of the utility model, the following technical solutions are adopted:

[0008] The utility model provides a system for preparing 1,4-cyclohexane dimethyl dicarboxylate, comprising: first feed pipeline, second feed pipeline and hydrogenation reactor,

[0009] The first feed pipeline is used for conveying dimethyl terephthalate, methanol and solid catalyst, and the first feed pipeline communicates with the hydrogenation reactor through the bottom of the hydrogenation reactor;

[0010] The second feed pipeline is used for conveying hydrogen, and the hydrogenation reactor is provided with a mass transfer intensifier, the upper and lower ends of the mass transfer intensifier are both provided with micro-bubble outlets, and the number of the upper end micro-bubble outlet is less than that of the lower end micro-bubble outlet; the second feed pipeline is connected with the mass transfer intensifier;

[0011] The hydrogenation reactor is a slurry bed reactor, the material outlet of the hydrogenation reactor is higher than the mass transfer intensifier along the vertical direction, and the material outlet is lower than the liquid level in the hydrogenation reactor along the vertical direction;

[0012] A baffle is arranged in the hydrogenation reactor close to the material outlet, the top of the baffle is located between the material outlet and the liquid level of the hydrogenation reactor along the vertical direction; the bottom of the baffle is inclinedly arranged along the direction close to the side wall of the hydrogenation reactor, and there is a gap between the bottom of the baffle and the side wall of the hydrogenation reactor; the baffle and the side wall where the material outlet is located form a settling tank.

[0013] In the above scheme, dimethyl terephthalate, methanol and solid catalyst are mixed in the first feed pipeline, which can make the solid catalyst uniformly distributed in the hydrogenation reactor, and help to better play the catalytic effect; by adopting a slurry bed reactor as the hydrogenation reactor, the hydrogenation reaction catalyst can be replaced in real time during production, thereby solving the problem of stopping to replace the catalyst in the prior art; by arranging the mass transfer intensifier in the hydrogenation reactor, hydrogen can be dispersed and broken into micron-sized micro-bubbles, thereby the gas-liquid mass transfer area can be increased, the gas-liquid mass transfer efficiency can be increased, and the reaction rate can be improved, and to a certain extent, the requirements of hydrogenation reaction on temperature and pressure can be reduced, thereby helping to reduce the reaction energy consumption; the mass transfer intensifier of the scheme adopts a horn-shaped structure with more outlets at one end and less outlets at one end, which can make the output micro-bubbles more reasonably distributed in the hydrogenation reactor, and can intensify the mixing of the solid catalyst in the liquid phase; by arranging a baffle near the material outlet in the hydrogenation reactor, the baffle and the side wall of the hydrogenation reactor can form an embedded settling tank, the reaction liquid in the hydrogenation reactor flows into the settling tank for sedimentation, the supernatant is output through the material outlet, and the turbid liquid flows back into the hydrogenation reactor through the bottom of the settling tank to continue to participate in the reaction, thereby the purity of the product output by the material outlet and the utilization rate of the catalyst can be improved, which helps to save costs.

[0014] Preferably, the number of the mass transfer intensifiers is two, and the second feed pipeline is connected to the two mass transfer intensifiers respectively; one of the two mass transfer intensifiers is located above the other mass transfer intensifier in the vertical direction, and the two mass transfer intensifiers are arranged staggered in the vertical direction.

[0015] In the above scheme, the two mass transfer intensifiers are arranged staggered in the vertical direction, which can make the lower end outlet of the upper mass transfer intensifier staggered with the upper end outlet of the lower mass transfer intensifier, and this arrangement can avoid the collision of the two micro-bubble streams to cause liquid dead zone, and the micro-bubbles sprayed by the two mass transfer intensifiers can agitate the reaction liquid in the hydrogenation reactor, which can on the one hand make the micro-bubbles uniformly distributed, further increase the mass transfer area and the contact area between the reaction materials, and improve the reaction efficiency, and on the other hand, the agitation of the reaction liquid can ensure the uniform distribution of the catalyst in the reaction liquid, and ensure the catalytic effect of the catalyst, which helps to further improve the reaction efficiency of the hydrogenation reaction.

[0016] Preferably, the system further comprises a first circulation pipeline; the inlet and outlet of the first circulation pipeline are both connected to the side wall of the hydrogenation reactor, and the inlet of the first circulation pipeline is located below the two mass transfer intensifiers in the vertical direction, and the outlet of the first circulation pipeline is located above the two mass transfer intensifiers.

[0017] In the above scheme, by setting the first circulating pipeline, the solid catalyst deposited at the bottom of the hydrogenation reactor can be pumped into the upper middle part of the hydrogenation reactor through the first circulating pipeline, so that the solid catalyst continues to participate in the reaction; and this way can stir the reaction liquid at the bottom of the hydrogenation reactor in the vertical direction, to some extent, to prevent the deposition of solid catalyst; in general, by setting the first circulating pipeline, the catalytic effect and utilization rate of the solid catalyst can be improved.

[0018] Preferably, the system further comprises a second circulating pipeline; the inlet and outlet of the second circulating pipeline are both connected to the side wall of the hydrogenation reactor, and the inlet of the second circulating pipeline is lower than the bottom of the baffle in the vertical direction, and the outlet of the second circulating pipeline is located between the two intensified mass transfer devices in the vertical direction.

[0019] In the above scheme, the lower slurry settled at the bottom of the settling tank can be directly input into the space between the two intensified mass transfer devices through the second circulating pipeline, and uniformly dispersed by the stirring of the micro-bubble flow of the two intensified mass transfer devices, which helps to further improve the utilization rate and catalytic effect of the catalyst.

[0020] Preferably, a plurality of baffles are arranged in the hydrogenation reactor, the plurality of baffles are arranged staggered, and the plurality of baffles are located between the baffle and the intensified mass transfer device in the vertical direction. Preferably, the baffles are arranged inclined downward away from the side wall of the hydrogenation reactor. This scheme can reduce the flow speed of the upper reaction liquid by arranging the plurality of baffles staggered, promote the settlement of the solid catalyst in the reaction liquid, and thus reduce the purity of the product output by the material outlet. In a further scheme, by arranging the baffles inclined downward, the settled solid catalyst can flow back into the reaction liquid below along the baffles, avoiding the accumulation of the settled solid catalyst on the baffles.

[0021] Preferably, a ring-shaped agitator is arranged at the bottom of the hydrogenation reactor; the ring-shaped agitator comprises a ring-shaped pipe and a plurality of nozzles arranged in an array below the ring-shaped pipe; the plurality of nozzles are arranged inclined downward; and the first feeding pipeline is connected to the ring-shaped pipe. The plurality of nozzles of the ring-shaped agitator spray the solid-liquid mixture in the first feeding pipeline into the hydrogenation reactor, which can disturb and stir the reaction liquid in the hydrogenation reactor, which on the one hand is conducive to the rapid mixing of the solid-liquid mixture with the reaction liquid, so that the solid catalyst is uniformly distributed; and on the other hand, the reaction liquid at the bottom of the hydrogenation reactor can be stirred to avoid the deposition of the solid catalyst at the bottom of the hydrogenation reactor, thereby further promoting the uniform distribution of the solid catalyst in the reaction liquid; at the same time, the ring-shaped agitator mainly stirs the reaction liquid at the bottom of the hydrogenation reactor in the horizontal direction, while the first circulating pipeline mainly plays a stirring role in the vertical direction, and the combination of the two can further improve the uniformity of the distribution of the solid catalyst.

[0022] Preferably, the system further comprises a sedimentation tank and a filter, the material outlet is connected to the sedimentation tank, a lower turbid liquid outlet of the sedimentation tank is connected to the filter, and a filter residue outlet of the filter is connected to the first feeding pipeline; preferably, the number of filters is two, and the two filters are arranged in parallel. The reacted material enters the sedimentation tank through the material outlet, and is precipitated in the sedimentation tank, and the lower turbid liquid therein enters the filter for filtration and separation, and the separated solid catalyst returns to the first feeding pipeline through the filter residue outlet. In a further aspect, the number of filters is two, and the two filters can adopt an application mode of one open and one closed, so as to avoid stopping for cleaning the filter, which helps to increase production efficiency.

[0023] Preferably, an arc-shaped filter cloth is arranged in the filter; the arc-shaped filter cloth divides an internal chamber of the filter into a filtration cavity and a filtrate cavity, and the filter residue outlet of the filter is arranged on a side wall of the filtration cavity; preferably, a guide plate is arranged at an inlet of the filter, and the guide plate extends downward and inclines in a direction close to the arc-shaped filter cloth. In this aspect, the filter cloth of the filter adopts a 1 / 4 circular arc design, which is more conducive to the recovery of the solid catalyst and can effectively prevent the solid catalyst from blocking the filter cloth; in a further aspect, a guide plate is arranged in the filter, which can play a guiding and buffering role, and can avoid the lower turbid liquid entering the filter from directly impacting the arc-shaped filter cloth, thereby ensuring the filtering effect of the arc-shaped filter cloth.

[0024] Preferably, the system further comprises a first rectifying tower and a second rectifying tower, and the supernatant outlet of the sedimentation tank and the filtrate outlet of the filter are both connected to the first rectifying tower; a tower bottom outlet of the first rectifying tower is connected to the second rectifying tower, and a tower top outlet is connected to the first feeding pipeline; and a tower top outlet of the second rectifying tower is used to output a product, and a tower bottom outlet is connected to the first feeding pipeline. The supernatant obtained through the sedimentation tank and the filtrate obtained through the filter enter the first rectifying tower for rectification, the methanol rectified out of the top of the first rectifying tower returns to the first feeding pipeline, and the tower bottom material flows into the second rectifying tower; the target product 1,4-cyclohexane dimethyl dicarboxylate is produced at the top of the second rectifying tower, and dimethyl terephthalate is produced at the bottom and is input into the first feeding pipeline to continue to participate in the reaction. This aspect can effectively improve the purity of the product through two rectification processes.

[0025] The skilled in the art can understand that the enhanced mass transfer device adopted by the utility model has been embodied in the prior patents of the inventor, such as the patents with the application numbers CN201610641119.6, CN201610641251.7, CN201710766435.0, the publication numbers CN106187660A, CN105903425A, CN205833127U and CN207581700U. The specific product structure and working principle of the micron bubble generator (i.e. bubble breaker) are introduced in detail in the prior patent CN201610641119.6. It is recorded in the application file that "the micron bubble generator comprises a body and a secondary breaking piece, the body has a cavity, the body is provided with an inlet communicating with the cavity, the opposite first end and the second end of the cavity are open, wherein the cross-sectional area of the cavity decreases from the middle part of the cavity to the first end and the second end of the cavity; the secondary breaking piece is arranged at least one of the first end and the second end of the cavity, a part of the secondary breaking piece is arranged in the cavity, and an annular channel is formed between the secondary breaking piece and the open hole of the cavity. The micron bubble generator further comprises a gas inlet pipe and a liquid inlet pipe." From the specific structure disclosed in the application file, it can be known that the specific working principle is that the liquid enters the micron bubble generator through the liquid inlet pipe tangentially, rotates at a high speed and cuts the gas, so that the gas bubbles are broken into micron-sized micro-bubbles, thereby improving the mass transfer area between the liquid phase and the gas phase, and the micron bubble generator in the patent belongs to a pneumatic bubble breaker.

[0026] In addition, it is recorded in the prior patent 201610641251.7 that the primary bubble breaker has a circulating liquid inlet, a circulating gas inlet and a gas-liquid mixture outlet, and the secondary bubble breaker is communicated with the feed inlet and the gas-liquid mixture outlet, which indicates that the bubble breaker needs to be mixed with gas and liquid, and in addition, it can be known from the subsequent drawings that the primary bubble breaker mainly uses circulating liquid as power, so the primary bubble breaker actually belongs to a liquid-driven type of enhanced reactor, and the secondary bubble breaker is communicated with the gas-liquid mixture into the rotating ball in the elliptical shape to rotate, so as to realize bubble breaking in the rotating process, so the secondary bubble breaker actually belongs to a gas-liquid linkage type of bubble breaker. Actually, whether it is a liquid-driven type of bubble breaker or a gas-liquid linkage type of bubble breaker, it belongs to a specific form of bubble breaker, however, the enhanced mass transfer device adopted by the utility model is not limited to the above-mentioned forms, and the specific structure of the bubble breaker recorded in the prior patents is only one of the forms that can be adopted by the utility model.

[0027] In addition, it is described in the prior patent 201710766435.0 that "the principle of the bubble breaker is high-speed jet flow to achieve mutual collision of gas"; and the specific structure of the bubble breaker is also described in the prior patent CN106187660, specifically see paragraphs

[0031] -

[0041] in the specification, and the drawing part, which has a detailed description of the specific working principle of the bubble breaker S-2, the top of the bubble breaker is a liquid phase inlet, and the side is a gas phase inlet, the liquid phase from the top provides the entrainment power, so as to achieve the effect of crushing into superfine bubbles, and it can be seen from the drawing that the bubble breaker is conical, and the diameter of the upper part is larger than that of the lower part, so that the liquid phase can better provide the entrainment power.

[0028] Because the bubble breaker was just developed in the early stage of the prior patent application, it was named as a micron bubble generator (CN201610641119.6) in the early stage, and with continuous technical improvement, it was renamed as a bubble breaker in the later stage, and now the reinforced mass transfer device in the utility model is equivalent to the previous micron bubble generator, micro-interface generator, etc., only the name is different.

[0029] The utility model also provides a kind of method for preparing 1,4-cyclohexane dimethyl dicarboxylate, which prepares 1,4-cyclohexane dimethyl dicarboxylate using the system of any one of the above embodiments.

[0030] Compared with the prior art, the utility model has the beneficial effects that:

[0031] 1, dimethyl terephthalate, methanol and solid catalyst are mixed in the first feed pipe, which can make the solid catalyst uniformly distributed in the hydrogenation reactor, and help to better play the catalytic effect;

[0032] 2, by adopting slurry bed reactor as hydrogenation reactor, hydrogenation reaction catalyst can be replaced in real time during production, thereby solving the problem of catalyst replacement in the prior art;

[0033] 3, by setting reinforced mass transfer device in hydrogenation reactor, hydrogen can be dispersed and broken into micron-sized micro-bubbles, so as to improve the gas-liquid mass transfer area, increase the gas-liquid mass transfer efficiency, and further help to improve the reaction rate, and this method can reduce the requirement of hydrogenation reaction on temperature and pressure to a certain extent, thereby helping to reduce the reaction energy consumption;

[0034] 4, the reinforced mass transfer device of the scheme adopts a horn-shaped structure with more outlets at one end and less outlets at one end, so that the output micro-bubbles can be more reasonably distributed in the hydrogenation reactor;

[0035] 5. By setting a baffle plate near the material outlet in the hydrogenation reactor, the baffle plate and the side wall of the hydrogenation reactor can form an internal settling tank, the reaction liquid in the hydrogenation reactor flows into the settling tank for settlement, the supernatant is output through the material outlet, and the turbid liquid flows back into the hydrogenation reactor through the bottom of the settling tank to continue to participate in the reaction, thereby improving the purity of the product output by the material outlet and the utilization rate of the catalyst, which helps to save costs. BRIEF DESCRIPTION OF DRAWINGS

[0036] Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The accompanying drawings are included to provide a description of the preferred embodiments and are not intended to limit the scope of the present application. Moreover, the same reference numerals are used throughout the various drawings to designate identical elements. In the drawings:

[0037] Figure 1 A schematic diagram of a system for preparing 1,4-cyclohexane dimethyl dicarboxylate according to Embodiment 1 of the present application is shown;

[0038] Figure 2 A structural schematic diagram of a ring-shaped agitator according to Embodiment 1 of the present application is shown;

[0039] Figure 3 A structural schematic diagram of a filter according to Embodiment 1 of the present application is shown.

[0040] In the drawings: 1, hydrogenation reactor; 2, partition; 3, mass transfer intensifier; 4, second feed pipe; 5, first circulation pipe; 6, ring-shaped agitator; 601, ring-shaped pipe; 602, nozzle; 7, first feed pipe; 8, baffle plate; 9, second circulation pipe; 10, settling tank; 11, filter; 12, first rectifying column; 13, second rectifying column; 14, arc-shaped filter cloth; 15, guide plate. DETAILED DESCRIPTION

[0041] The technical solutions of the present application will be described clearly and completely in combination with the drawings and specific embodiments, but those skilled in the art will understand that the following described embodiments are part of the embodiments of the present application, not all the embodiments, and are only used to illustrate the present application, and should not be considered as limiting the scope of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application. The specific conditions are not specified in the embodiments, and are carried out according to the conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used are not specified by the manufacturer, and are conventional products that can be purchased on the market.

[0042] In the description of the utility model, it needs to explain, the term "center", "upper", "lower", "left", "right", "vertical", "horizontal", "internal", "external" and so on indicate the orientation or positional relationship is based on the orientation or positional relationship shown in the drawing, only for the convenience of describing the utility model and simplifying the description, and cannot indicate or imply that the device or element must have a particular orientation, a particular orientation and operation, therefore cannot be understood as a limitation on the utility model. In addition, the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0043] In the description of the utility model, it needs to explain, unless otherwise expressly provided and limited, the terms "mounting", "connecting", "connecting" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected, it can be mechanically connected, or it can be electrically connected, it can be directly connected, or it can be indirectly connected through an intermediate medium, it can be the communication inside two elements. For ordinary skilled in the art, the specific meaning of the above terms in the utility model can be understood according to the specific circumstances.

[0044] In order to more clearly describe the technical scheme in the utility model, the following is described in the form of specific examples.

[0045] Example 1

[0046] Combined with reference Figures 1-3 The embodiment provides a system for preparing 1,4-cyclohexane dimethyl dicarboxylate, which comprises: a first feed pipeline 7, a second feed pipeline 4 and a hydrogenation reactor 1; the first feed pipeline 7 is used for conveying dimethyl terephthalate, methanol and a solid catalyst, and the first feed pipeline 7 communicates the hydrogenation reactor 1 through the bottom of the hydrogenation reactor 1; the second feed pipeline 4 is used for conveying hydrogen, and the hydrogenation reactor 1 is provided with a mass transfer intensifier 3, the upper and lower ends of the mass transfer intensifier 3 are provided with micro-bubble outlets, and the number of the upper end micro-bubble outlet is less than that of the lower end micro-bubble outlet; the second feed pipeline 4 is connected with the mass transfer intensifier 3; the hydrogenation reactor 1 is a slurry bed reactor, the material outlet of the hydrogenation reactor 1 is higher than the mass transfer intensifier 3 in the vertical direction, and the material outlet is lower than the liquid level in the hydrogenation reactor 1 in the vertical direction; the hydrogenation reactor 1 is provided with a baffle 8 close to the material outlet, the top of the baffle 8 is located between the material outlet and the liquid level of the hydrogenation reactor 1 in the vertical direction; the bottom of the baffle 8 is inclinedly arranged along the direction close to the side wall of the hydrogenation reactor 1, and there is a gap between the bottom of the baffle 8 and the side wall of the hydrogenation reactor 1; the baffle 8 and the side wall where the material outlet is located form a settling tank.

[0047] In the scheme of the present embodiment, dimethyl terephthalate, methanol and solid catalyst can be mixed in advance and then input into the hydrogenation reactor 1 through the first feeding pipeline 7. The solid catalyst can be a powder-like ruthenium-rhenium catalyst, which can be prepared by an equal-impregnation method, and the total loading of the ruthenium-rhenium bimetal is 0.3%-5%, and the carrier is one of activated carbon, carbon black, carbon nanotube and carbon nanofiber.

[0048] It can be understood that, in order to ensure the flow of materials in each pipeline, a water pump can be arranged on the pipeline, which will not be described herein.

[0049] According to the above description, the number of the upper micro-bubble outlets of the intensified mass transfer device 3 is less than the number of the lower micro-bubble outlets in the present embodiment. In the present embodiment, the length ratio of the upper and lower of the intensified mass transfer device 3 is 5:2.

[0050] In the present embodiment, the baffle 8 and the side wall where the material outlet is located form a settling tank. The volume of the settling tank can be 1 / 20-1 / 10 of the volume of the hydrogenation reactor 1, the height of the settling tank can be 1 / 5-3 / 5 of the height of the hydrogenation reactor 1, and the width of the settling tank can be 1 / 10-1 / 5 of the width of the hydrogenation reactor 1, wherein the height of the lower slurry is 1 / 10-1 / 5 of the height of the tank.

[0051] As shown in Figure 1 In the present embodiment, the number of the intensified mass transfer devices 3 is two, and the second feeding pipeline 4 is connected to the two intensified mass transfer devices 3 respectively; one of the two intensified mass transfer devices 3 is located above the other intensified mass transfer device 3 in the vertical direction, and the two intensified mass transfer devices 3 are staggered in the vertical direction. The lower outlet of the upper intensified mass transfer device 3 can output a micro-bubble flow downward, and the upper outlet of the lower intensified mass transfer device 3 can output a micro-bubble flow upward. Since the two micro-bubble flows are staggered in the vertical direction, a counterclockwise stirring force can be generated between the two intensified mass transfer devices 3 by the two micro-bubble flows.

[0052] Continuing to refer to Figure 1 In the present embodiment, the system further comprises a first circulation pipeline 5; the inlet and outlet of the first circulation pipeline 5 are both connected to the side wall of the hydrogenation reactor 1, and the inlet of the first circulation pipeline 5 is located below the two intensified mass transfer devices 3 in the vertical direction (i.e. it is located below the lower intensified mass transfer device 3 among the two intensified mass transfer devices 3), and the outlet of the first circulation pipeline 5 is located above the two intensified mass transfer devices 3 (i.e. it is located above the upper intensified mass transfer device 3 among the two intensified mass transfer devices 3). The reaction liquid at the bottom of the hydrogenation reactor 1 is pumped into the upper of the two intensified mass transfer devices 3 through the first circulation pipeline 5.

[0053] Continuing to refer to Figure 1In the embodiment, the system further comprises a second circulation pipeline 9; the inlet and outlet of the second circulation pipeline 9 are connected to the side wall of the hydrogenation reactor 1, and the inlet of the second circulation pipeline 9 is lower than the bottom of the baffle 8 in the vertical direction, and the outlet of the second circulation pipeline 9 is located between the two enhanced mass transfer devices 3 in the vertical direction. The underflow of the settling tank is pumped into the space between the two enhanced mass transfer devices 3 through the second circulation pipeline 9.

[0054] With reference to the drawings Figure 1 The hydrogenation reactor 1 is provided with a plurality of partitions 2, the plurality of partitions 2 are staggered, and the plurality of partitions 2 are located between the baffle 8 and the enhanced mass transfer device 3 in the vertical direction. In the embodiment, the partitions 2 are inclined downward away from the side wall of the hydrogenation reactor 1.

[0055] With reference to the drawings Figure 1 , 2 The hydrogenation reactor 1 is provided with a plurality of partitions 2, the plurality of partitions 2 are staggered, and the plurality of partitions 2 are located between the baffle 8 and the enhanced mass transfer device 3 in the vertical direction. In the embodiment, the partitions 2 are inclined downward away from the side wall of the hydrogenation reactor 1.

[0056] In Figure 1 the embodiment, the inlet of the first circulation pipeline 5 is located above the ring-shaped disturbance device 6, and the outlet is located below the partition 2. The inlet of the second circulation pipeline 9 is located above the partition 2.

[0057] In the embodiment, as shown in Figure 1 , the system further comprises a settling tank 10, a filter 11, a first rectifying column 12 and a second rectifying column 13; the material outlet is connected to the settling tank 10, the underflow outlet of the settling tank 10 is connected to the filter 11, and the filter residue outlet of the filter 11 is connected to the first feed pipeline 7; the supernatant outlet of the settling tank 10 and the filtrate outlet of the filter 11 are both connected to the first rectifying column 12; the bottom outlet of the first rectifying column 12 is connected to the second rectifying column 13, and the top outlet is connected to the first feed pipeline 7; the top outlet of the second rectifying column 13 is used to output the product, and the bottom outlet is connected to the first feed pipeline 7. The reacted material enters the settling tank 10 through the material outlet and is precipitated in the settling tank 10, and the underflow enters the filter 11 for filtration and separation, and the separated solid catalyst returns to the first feed pipeline 7 through the filter residue outlet. The supernatant obtained from the settling tank 10 and the filtrate obtained from the filter 11 enter the first rectifying column 12 for rectification, the methanol rectified from the top of the first rectifying column 12 returns to the first feed pipeline 7, and the bottom material flows into the second rectifying column 13; the target product 1,4-cyclohexane dimethyl dicarboxylate is produced from the top of the second rectifying column 13, and terephthalic acid dimethyl ester is produced from the bottom and is input into the first feed pipeline 7 to continue to participate in the reaction.

[0058] In the embodiment, the number of filters 11 is two, and the two filters 11 are arranged in parallel. In actual use, the two filters 11 can adopt an application mode of one open and one closed to avoid stopping due to cleaning of the filter 11, which helps to increase production efficiency.

[0059] Referring to Figure 3 In the embodiment, the filter 11 is provided with an arc-shaped filter cloth 14; the arc-shaped filter cloth 14 divides the internal chamber of the filter 11 into a filtering cavity and a filtrate cavity, and the filter residue outlet of the filter 11 is arranged on the side wall of the filtering cavity; the inlet of the filter 11 is provided with a guide plate 15, which is arranged to extend downwardly and incline toward the arc-shaped filter cloth 14. In the embodiment, the filter cloth of the filter 11 adopts a 1 / 4 circular arc design.

[0060] The embodiment also provides a method for preparing dimethyl 1,4-cyclohexanedicarboxylate, which applies the above system to prepare dimethyl 1,4-cyclohexanedicarboxylate.

[0061] The specific steps of the method are as follows: first, the powdered ruthenium-rhenium catalyst is loaded into the hydrogenation reactor 1, dimethyl terephthalate (dissolved in methanol) and hydrogen are introduced into the micro-interface intensifier unit of the hydrogenation reactor 1 at a molar ratio of 1:4 to form a micro-interface system, and dimethyl 1,4-cyclohexanedicarboxylate is generated under a reaction pressure of 1.0 MPa-3.0 MPa and a reaction temperature of 30℃-100℃ for 1-2 hours. During the reaction process, the powdered ruthenium-rhenium catalyst can be mixed into the first feed pipe 7 as needed to supplement the catalyst in real time. The reacted material flows from bottom to top in the hydrogenation reactor 1, flows into the sedimentation tank 10 from the top to perform sedimentation, the supernatant flows into the first rectifying column 12, and the turbid liquid is separated by filtration, the filtered solid catalyst is returned to the hydrogenation reactor 1 for recycling, and the filtrate flows into the first rectifying column 12. The methanol produced at the top of the first rectifying column 12 is introduced into the hydrogenation reactor 1 for recycling, and the material at the bottom is introduced into the second rectifying column 13. The target product dimethyl 1,4-cyclohexanedicarboxylate is produced at the top of the second rectifying column 13, and dimethyl terephthalate is produced at the bottom and introduced into the hydrogenation reactor 1 for recycling.

[0062] In this example, the specific process for preparing dimethyl 1,4-cyclohexanedicarboxylate is as follows: 1.0 kg / h of hydrogen is introduced into the enhanced mass transfer device of the hydrogenation reactor, and the feed temperature is controlled at about 40°C. 24.3 kg / h of dimethyl terephthalate and 100.0 kg / h of methanol are introduced into the hydrogenation reactor via the first feed pipe, and the feed temperature is controlled at about 30°C. The hydrogenation reactor slurry bed is loaded with powdered ruthenium-rhenium catalyst, and the reaction pressure is 3.0 MPa, and the reaction temperature is 100°C. During the reaction, the catalyst can be supplemented in real time through the first feed pipe. The reacted material flows from bottom to top in the hydrogenation reactor, flows into the sedimentation tank at the top for sedimentation, and the supernatant flows into the first rectifying column. The turbid liquid is separated by filtration, the filtered solid catalyst is returned to the hydrogenation reactor for recycling, and the filtrate flows into the first rectifying column. The methanol produced at the top of the first rectifying column is introduced into the hydrogenation reactor for recycling, and the bottom material is introduced into the second rectifying column. The target product dimethyl 1,4-cyclohexanedicarboxylate is produced at the top of the second rectifying column, and dimethyl terephthalate is produced at the bottom and introduced into the hydrogenation reactor for recycling. After the reaction is completed, 24.2 kg / h of the target product dimethyl 1,4-cyclohexanedicarboxylate is obtained, and the selectivity reaches 99.7%.

[0063] Example 2

[0064] The system used in this example is the same as in Example 1, and the specific process for preparing dimethyl 1,4-cyclohexanedicarboxylate in this example is as follows: 1.0 kg / h of hydrogen is introduced into the micro-interface enhanced unit of the hydrogenation reactor, and the feed temperature is controlled at about 40°C. 24.3 kg / h of dimethyl terephthalate and 100.0 kg / h of methanol are introduced into the hydrogenation reactor from the bottom, and the feed temperature is controlled at about 30°C. The hydrogenation reactor slurry bed is loaded with powdered ruthenium-rhenium catalyst, and the reaction pressure is 3.0 MPa, and the reaction temperature is 65°C. During the reaction, the catalyst can be supplemented in real time through the first feed pipe. The reacted material flows from bottom to top in the hydrogenation reactor, flows into the sedimentation tank at the top for sedimentation, and the supernatant flows into the first rectifying column. The turbid liquid is separated by filtration, the filtered solid catalyst is returned to the hydrogenation reactor for recycling, and the filtrate flows into the first rectifying column. The methanol produced at the top of the first rectifying column is introduced into the hydrogenation reactor for recycling, and the bottom material is introduced into the second rectifying column. The target product dimethyl 1,4-cyclohexanedicarboxylate is produced at the top of the second rectifying column, and dimethyl terephthalate is produced at the bottom and introduced into the hydrogenation reactor for recycling. After the reaction is completed, 23.7 kg / h of the target product dimethyl 1,4-cyclohexanedicarboxylate is obtained, and the selectivity reaches 98.8%.

[0065] Example 3

[0066] The system used in this example is the same as that of Example 1. The specific process for preparing dimethyl 1,4-cyclohexanedicarboxylate in this example is as follows: 1.0 kg / h of hydrogen is introduced into the micro-interface intensifier unit of the hydrogenation reactor, and the feed temperature is controlled at about 40°C. 24.3 kg / h of dimethyl terephthalate and 100.0 kg / h of methanol are introduced into the hydrogenation reactor from the bottom, and the feed temperature is controlled at about 30°C. The hydrogenation reactor slurry bed is loaded with powdered ruthenium-rhenium catalyst, the reaction pressure is 3.0 MPa, and the reaction temperature is 30°C. During the reaction, the catalyst can be supplemented in real time through the first feed pipe. The reacted material flows from bottom to top in the hydrogenation reactor, flows into the sedimentation tank at the top for sedimentation, the supernatant flows into the first rectifying column, the lower turbidity liquid is separated by filtration, the filtered solid catalyst is returned to the hydrogenation reactor for recycling, and the filtrate flows into the first rectifying column. The methanol produced at the top of the first rectifying column is introduced into the hydrogenation reactor for recycling, and the bottom material is introduced into the second rectifying column. The target product dimethyl 1,4-cyclohexanedicarboxylate is produced at the top of the second rectifying column, and dimethyl terephthalate is produced at the bottom and introduced into the hydrogenation reactor for recycling. After the reaction is completed, 21.5 kg / h of the target product dimethyl 1,4-cyclohexanedicarboxylate is obtained, and the selectivity reaches 95.5%.

[0067] Example 4

[0068] The system used in this example is the same as that of Example 1. The specific process for preparing dimethyl 1,4-cyclohexanedicarboxylate in this example is as follows: 1.0 kg / h of hydrogen is introduced into the micro-interface intensifier unit of the hydrogenation reactor, and the feed temperature is controlled at about 40°C. 24.3 kg / h of dimethyl terephthalate and 100.0 kg / h of methanol are introduced into the hydrogenation reactor from the bottom, and the feed temperature is controlled at about 30°C. The hydrogenation reactor slurry bed is loaded with powdered ruthenium-rhenium catalyst, the reaction pressure is 2.0 MPa, and the reaction temperature is 100°C. During the reaction, the catalyst can be supplemented in real time through the first feed pipe. The reacted material flows from bottom to top in the hydrogenation reactor, flows into the sedimentation tank at the top for sedimentation, the supernatant flows into the first rectifying column, the lower turbidity liquid is separated by filtration, the filtered solid catalyst is returned to the hydrogenation reactor for recycling, and the filtrate flows into the first rectifying column. The methanol produced at the top of the first rectifying column is introduced into the hydrogenation reactor for recycling, and the bottom material is introduced into the second rectifying column. The target product dimethyl 1,4-cyclohexanedicarboxylate is produced at the top of the second rectifying column, and dimethyl terephthalate is produced at the bottom and introduced into the hydrogenation reactor for recycling. After the reaction is completed, 23.8 kg / h of the target product dimethyl 1,4-cyclohexanedicarboxylate is obtained, and the selectivity reaches 99.1%.

[0069] Example 5

[0070] The system used in this example is the same as that of Example 1. The specific process for preparing 1,4-cyclohexane dimethyl dicarboxylate in this example is as follows: 1.0 kg / h of hydrogen is introduced into the micro-interface intensifier unit of the hydrogenation reactor, and the feed temperature is controlled at about 40°C. 24.3 kg / h of dimethyl terephthalate and 100.0 kg / h of methanol are introduced into the hydrogenation reactor from the bottom, and the feed temperature is controlled at about 30°C. The hydrogenation reactor slurry bed is filled with powdered ruthenium-rhenium catalyst, the reaction pressure is 1.0 MPa, and the reaction temperature is 100°C. During the reaction, the catalyst can be supplemented in real time through the first feed pipe. The reacted material flows from bottom to top in the hydrogenation reactor, flows into the sedimentation tank at the top, and is precipitated. The supernatant flows into the first rectifying column, and the turbid liquid is separated by filtration. The filtered solid catalyst is returned to the hydrogenation reactor for recycling, and the filtrate flows into the first rectifying column. The methanol produced at the top of the first rectifying column is introduced into the hydrogenation reactor for recycling, and the material at the bottom is introduced into the second rectifying column. The target product 1,4-cyclohexane dimethyl dicarboxylate is produced at the top of the second rectifying column, and dimethyl terephthalate is produced at the bottom and introduced into the hydrogenation reactor for recycling. After the reaction is completed, 23.1 kg / h of the target product 1,4-cyclohexane dimethyl dicarboxylate is obtained, and the selectivity reaches 97.6%.

[0071] Example 6

[0072] The difference between this example and Example 1 is that no annular disturber is arranged in the hydrogenation reactor, and the material in the first feed pipe directly flows into the hydrogenation reactor through the bottom of the hydrogenation reactor. After hydrogenation and rectification separation, 23.1 kg / h of the target product 1,4-cyclohexane dimethyl dicarboxylate is obtained, and the selectivity is 98.5%.

[0073] Example 7

[0074] The difference between this example and Example 1 is that one of the two intensifying mass transfer devices is vertically located directly above the other intensifying mass transfer device, and the lower end outlet of the upper intensifying mass transfer device is opposite to the upper end outlet of the lower intensifying mass transfer device. After hydrogenation and rectification separation, 20.3 kg / h of the target product 1,4-cyclohexane dimethyl dicarboxylate is obtained, and the selectivity is 94.3%.

[0075] Comparative Example 1

[0076] The difference between this example and Example 1 is that no intensifying mass transfer device is arranged in the hydrogenation reactor. After hydrogenation and rectification separation, 15.1 kg / h of the target product 1,4-cyclohexane dimethyl dicarboxylate is obtained, and the selectivity is 75.5%.

[0077] Comparative Example 2

[0078] The difference between the system of this example and example 1 is that no mass transfer intensifier is arranged in the hydrogenation reactor. The specific process for preparing 1,4-cyclohexane dimethyl dicarboxylate in this example is as follows: 1.0 kg / h of hydrogen is introduced into the hydrogenation reactor (remove the micro-interface intensifier unit), and the feed temperature is controlled at about 40℃; 24.3 kg / h of dimethyl terephthalate and 100.0 kg / h of methanol are introduced into the hydrogenation reactor from the bottom, and the feed temperature is controlled at about 30℃. The hydrogenation reactor slurry bed is filled with powdered ruthenium-rhenium catalyst, and the reaction pressure is 5.0 MPa, and the reaction temperature is 130℃. During the reaction, the catalyst can be supplemented in real time through the first feed pipe. The reacted material flows from bottom to top in the hydrogenation reactor, flows into the sedimentation tank from the top, and the supernatant flows into the first rectifying tower, and the turbid liquid is separated by filtration, and the filtered solid catalyst is returned to the hydrogenation reactor for recycling, and the filtrate flows into the first rectifying tower. The methanol produced at the top of the first rectifying tower is introduced into the hydrogenation reactor for recycling, and the bottom material is introduced into the second rectifying tower. The target product 1,4-cyclohexane dimethyl dicarboxylate is produced at the top of the second rectifying tower, and dimethyl terephthalate is produced at the bottom and introduced into the hydrogenation reactor for recycling. After the reaction is completed, 17.5 kg / h of the target product 1,4-cyclohexane dimethyl dicarboxylate is obtained, and the selectivity reaches 82.3%.

[0079] According to examples 1-7, it can be seen that the system of the utility model has high yield and high selectivity when preparing 1,4-cyclohexane dimethyl dicarboxylate. According to the data of examples 1-5 and comparative examples 1-2, the following conclusions can be drawn: increasing the reaction temperature of hydrogenation reaction can increase the solubility of dimethyl terephthalate in methanol, so increasing the temperature can increase the reaction rate of dimethyl terephthalate hydrogenation and improve the conversion rate of dimethyl terephthalate, but increasing the temperature can reduce the solubility of hydrogen in the catalyst system, weaken the adsorption effect on the surface of the catalyst, and too high reaction temperature can accelerate the increase of the grain size of the catalyst and accelerate the aging of the catalyst. Therefore, the reaction temperature should be controlled at 30-100℃. The reaction conditions are relatively mild, which can effectively reduce the energy consumption.

[0080] Comparing example 1 and example 6, it can be seen that the product yield and selectivity of example 1 are better than those of example 6. This may be due to the fact that the annular disturber in example 1 can play a stirring role at the bottom of the hydrogenation reactor, promote the uniform distribution of the catalyst, avoid the settlement of the catalyst, thereby improve the catalytic effect of the catalyst, and further improve the product yield and selectivity.

[0081] Comparing example 1 and example 7, it can be seen that the product yield and selectivity of example 1 are both superior to example 7. This can be due to the fact that the two strong mass transfer device outlets are opposite in example 7, causing a dead zone in the reaction liquid. Example 1 achieves agitation of the reaction liquid by staggering the two strong mass transfer device outlets, so the uniformity of the distribution of catalyst and micro-bubbles in the reaction liquid in the hydrogenation reactor in example 1 is better, the reaction rate is fast, and thus the product yield and selectivity are both superior to example 7.

[0082] Comparing example 1, comparative example 1 and comparative example 2, it can be seen that the product yield and selectivity in example 1 are both superior to comparative example 1 and comparative example 2. This shows that the use of the strong mass transfer device in the utility model improves the interfacial mass transfer area of the raw materials and improves the reaction rate. This also proves that the use of the strong mass transfer device can greatly improve the selectivity of 1,4-cyclohexane dimethyl ester in the hydrogenation reaction and has a significant effect on reaction intensification.

[0083] In summary, the system of the utility model uses a slurry bed reactor for hydrogenation reaction and sets a strong mass transfer device in the hydrogenation reactor, which can effectively increase the interfacial mass transfer area of the gas-liquid two-phase, thereby helping to increase the gas-liquid mass transfer efficiency and reaction rate.

[0084] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the utility model, and not to limit them; although the utility model has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the utility model.

Claims

1. A system for producing dimethyl 1,4-cyclohexanedicarboxylate, characterized by, The application relates to a hydrogenation reactor. The first feed pipeline is used for conveying dimethyl terephthalate, methanol and a solid catalyst, and the first feed pipeline communicates with the hydrogenation reactor through the bottom of the hydrogenation reactor. The second feed pipeline is used for conveying hydrogen, and the hydrogenation reactor is provided with a mass transfer intensifier, the upper and lower ends of the mass transfer intensifier are provided with micro-bubble outlets, and the number of the upper end micro-bubble outlets is less than that of the lower end micro-bubble outlets; the second feed pipeline is connected with the mass transfer intensifier. The hydrogenation reactor is a slurry bed reactor, the material outlet of the hydrogenation reactor is higher than the mass transfer intensifier in the vertical direction, and the material outlet is lower than the liquid level in the hydrogenation reactor in the vertical direction. A baffle is arranged near the material outlet in the hydrogenation reactor, the top of the baffle is located between the material outlet and the liquid level of the hydrogenation reactor in the vertical direction; the bottom of the baffle is arranged in a direction close to the side wall of the hydrogenation reactor, and a gap is formed between the bottom of the baffle and the side wall of the hydrogenation reactor; a settling tank is formed between the baffle and the side wall where the material outlet is located. The number of the mass transfer intensifiers is two, and the second feed pipeline is connected with the two mass transfer intensifiers respectively; one of the two mass transfer intensifiers is located above the other mass transfer intensifier in the vertical direction, and the two mass transfer intensifiers are arranged in a staggered mode in the vertical direction.

2. The system of claim 1, wherein, The first circulation pipeline is further arranged; the inlet and outlet of the first circulation pipeline are connected with the side wall of the hydrogenation reactor, and the inlet of the first circulation pipeline is located below the two mass transfer intensifiers in the vertical direction, and the outlet of the first circulation pipeline is located above the two mass transfer intensifiers.

3. The system of claim 2, wherein, The second circulation pipeline is further arranged; the inlet and outlet of the second circulation pipeline are connected with the side wall of the hydrogenation reactor, and the inlet of the second circulation pipeline is lower than the bottom of the baffle in the vertical direction, and the outlet of the second circulation pipeline is located between the two mass transfer intensifiers in the vertical direction.

4. The system of claim 2, wherein, A plurality of partitions are arranged in the hydrogenation reactor, the plurality of partitions are arranged in a staggered mode, and the plurality of partitions are located between the baffle and the mass transfer intensifiers in the vertical direction.

5. The system according to any of claims 1-4, characterized in that, The bottom of the hydrogenation reactor is provided with a ring-shaped agitator; the ring-shaped agitator comprises a ring-shaped pipe and a plurality of nozzles arranged in an array below the ring-shaped pipe; the plurality of nozzles are arranged in a downward inclined mode; and the first feed pipeline is connected with the ring-shaped pipe.

6. The system according to any of claims 1-4, characterized in that, A settling tank and a filter are further arranged; the material outlet is connected with the settling tank, the lower turbid liquid outlet of the settling tank is connected with the filter, and the filter residue outlet of the filter is connected with the first feed pipeline.

7. The system according to any of claims 1-4, characterized in that, An arc-shaped filter cloth is arranged in the filter; the arc-shaped filter cloth divides the internal chamber of the filter into a filtering cavity and a filtrate cavity, and the filter residue outlet of the filter is arranged on the side wall of the filtering cavity.

8. The system of claim 7, wherein, A guide plate is arranged at the inlet of the filter, and the guide plate is arranged in a downward inclined mode close to the arc-shaped filter cloth.

9. The system of claim 8, wherein, ​ 10. The system of claim 7, wherein, The first distillation column and the second distillation column are further included, the supernatant outlet of the sedimentation tank and the filtrate outlet of the filter are connected to the first distillation column; the bottom outlet of the first distillation column is connected to the second distillation column, and the top outlet is connected to the first feeding pipeline; The top outlet of the second distillation column is used for outputting products, and the bottom outlet is connected to the first feeding pipeline.

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