CN115448815A - Process for synthesizing 1, 4-butanediol by applying loop current hydrogenation reactor to Reppe method - Google Patents

Process for synthesizing 1, 4-butanediol by applying loop current hydrogenation reactor to Reppe method Download PDF

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CN115448815A
CN115448815A CN202211077299.1A CN202211077299A CN115448815A CN 115448815 A CN115448815 A CN 115448815A CN 202211077299 A CN202211077299 A CN 202211077299A CN 115448815 A CN115448815 A CN 115448815A
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butanediol
catalyst
acetylene
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刘巍
杜金颖
孟令旭
王宇翀
王伊璇
高朔
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Liaoning University
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Abstract

The invention belongs to the field of chemical product synthesis, and relates to a process for synthesizing 1, 4-butanediol by applying a circulating hydrogenation reactor to a Reppe method. The method comprises the following steps: preparing acetylene by partial oxidation of natural gas: respectively feeding natural gas and oxygen into a cracking furnace, cracking at 1800 ℃, separating and concentrating to obtain crude acetylene gas; acetylene and formaldehyde react under the condition of a catalyst to prepare 1, 4-butynediol, and impurities are removed; 1, 4-butanediol is prepared by hydrogenating 1, 4-butynediol under the condition of a catalyst. The process improves the existing 1,4 butanediol production process, uses a natural gas partial oxidation method, and avoids the use of calcium carbide and water for hydrogenation to pollute the environment. The loop reactor is used, so that the 1, 4-butynediol can be subjected to hydrogenation reaction fully to generate 1, 4-butanediol, the energy consumption is reduced, and the abrasion of the catalyst is reduced.

Description

Process for synthesizing 1, 4-butanediol by applying loop current hydrogenation reactor to Reppe method
Technical Field
The invention belongs to the field of chemical product synthesis, and relates to a process for synthesizing 1, 4-butanediol by applying a circulating hydrogenation reactor to a Rapper method.
Background
1, 4-Butanediol (BDO) is an important chemical raw material, and the BDO is used for preparing synthetic rubber monomer butadiene at first, and then the butadiene has more economic sources. The main downstream applications of BDO include: THF, GBL, PBT, PU. Wherein the THF is mainly used as follows: as a solvent, the product can be used in the industries of medicine, spice, chemical industry and the like; as chemical raw material, PTMEG can be produced, and can be used for spandex, tetrahydrothiophene, pyrrolidone, 2, 3-dichlorotetrahydrofuran, 1, 4-dichloroethane, ink and perfume, etc. The main uses of GBL are: as a solvent, the solvent can dissolve various high polymers such as PVC, PAN, PVB, epoxy resin and the like, and is a special solvent for varnish, spray paint and capacitor electrolyte; produce herbicide (dichlorophenoxybutyric acid), azo dye, methionine, perfume, medicine, NMP (N-methyl pyrrolidone), gamma-butyrolactam, NVP, etc. The PBT has the main purposes that: engineering plastics can be used for automobiles, electronic and electric appliances, light industry and industrial parts; producing films and optical fibers. The PU has the main purposes that: tires, hydraulic seals, pipe liners, automotive instrument panels and bumpers, ski boot sole stock solutions, adhesives, elastomers, sizing, synthetic leather, and the like. In addition, the national improvement on the plastic pollution control is promoted from the original 'plastic limit' to 'plastic forbidding', and with the increasing attention of people on the plastic pollution and the implementation of a new edition of 'plastic forbidding' instruction, the application of BDO downstream products can meet an explosion period, and meanwhile, BDO can meet a new peak of continuously increasing application.
Most of the commonly used methods for preparing 1, 4-butanediol are an alkyne-aldehyde method and a cis-anhydride method, and compared with the alkyne-aldehyde method, the cis-anhydride method has the defects of complicated process flow and large influence caused by the restriction of raw material cis-anhydride. The alkyne-aldehyde method has long development history, mature process, high product yield and few byproducts. However, the process flow for preparing acetylene from natural gas is flammable and explosive, and in addition, the reactors commonly used in the hydrogenation step of the existing acetylene aldehyde method comprise a fluidized bed reactor and a fixed bed reactor. Both reactors are essentially capable of meeting the reaction requirements. But also has some disadvantages, fluidized bed reactors: the yield of the target product is low; the reaction conversion rate is low; the catalyst is accelerated to be pulverized and has large loss; the operation is empirical and random. A fixed bed reactor: poor heat transfer; the catalyst cannot be replaced during the operation process, and the catalyst is not suitable for the reaction which needs frequent regeneration.
Disclosure of Invention
In order to solve the problems, the invention provides a process for applying a circulating hydrogenation reactor to synthesize 1, 4-butanediol by a Rapper method, which comprises the following steps:
1) Partial oxidation of natural gas to acetylene: respectively feeding natural gas and oxygen into a cracking furnace, cracking at 1800 ℃, separating and concentrating to obtain crude acetylene gas;
2) Acetylene and formaldehyde react under the condition of a catalyst to prepare 1, 4-butynediol, and impurities are removed;
3) 1, 4-butynediol is hydrogenated under the condition of a catalyst to prepare 1, 4-butanediol.
Preferably, the above-mentioned process for applying a ring flow hydrogenation reactor to the synthesis of 1, 4-butanediol by the Rappe method further comprises impurity removal treatment in step 1), wherein the impurity removal treatment comprises purification and refining of acetylene, and the refining is to use activated carbon to adsorb higher alkyne in acetylene raw material gas.
Preferably, the above-mentioned process for synthesizing 1, 4-butanediol by using a loop current hydrogenation reactor is a process for synthesizing 1, 4-butanediol by the Rappe method, and the catalyst in the step 2) is copper, bismuth and aluminum.
Preferably, the loop hydrogenation reactor is applied to the process for synthesizing 1, 4-butanediol by the Rapper method, and the gas lift loop reactor is used for hydrogenation in the step 3).
Preferably, the loop hydrogenation reactor is applied to the process for synthesizing 1, 4-butanediol by the Rapper method, and the airlift loop reactor has the structure that: the middle position of the top of the upper end of the airlift loop reactor is provided with a hydrogen feeding hole, a compressor is arranged below the hydrogen feeding hole, the compressor is sequentially connected with a diaphragm and a separator, a hollow pipe is arranged below the separator, the hollow pipe extends to a position close to the bottom of the airlift loop reactor, the top of the upper end of the airlift loop reactor is also provided with a butynediol feeding hole, a stirrer and a heat exchange pipe are also arranged inside the airlift loop reactor, and the upper part and the lower part of the side surface of the airlift loop reactor are respectively provided with a first discharging hole and a second discharging hole.
Preferably, the above-mentioned one applies the ring-flow hydrogenation reactor to the process for synthesizing 1, 4-butanediol by the Rapspee method, and the catalyst used in step 3) is one or more of Raney nickel, raney cobalt, raney iron, raney copper, pd/C and Ru/C.
Preferably, the above process for synthesizing 1, 4-butanediol by using a circulating hydrogenation reactor in the Rapspee method, the catalyst used in step 3) is a Raney nickel catalyst, and the Raney nickel catalyst is a powdery Raney nickel catalyst or an amorphous Raney nickel catalyst.
Preferably, the preparation method of the powdery raney nickel catalyst comprises the following steps of heating and melting solid powder of Ni and Al under the protection of argon to obtain uniform nickel-aluminum alloy, cooling to room temperature, crushing, ball-milling to obtain nickel-aluminum alloy powder, slowly and repeatedly adding the nickel-aluminum alloy powder into a sodium hydroxide solution, activating, washing to be neutral after activation is finished, and placing in water for storage.
Preferably, the above-mentioned method for preparing the amorphous raney nickel catalyst by applying the loop hydrogenation reactor to the process for synthesizing 1, 4-butanediol by the raney method comprises the steps of putting a nickel-aluminum alloy block into a reaction tube, introducing 25 wt% sodium hydroxide solution at a flow rate of 0.5mL/min, reacting for 2h at 50 ℃, and after the activation is completed, washing to be neutral to obtain the amorphous raney nickel catalyst.
Preferably, the above-mentioned process for synthesizing 1, 4-butanediol by using a circulating hydrogenation reactor in the Reppe method, in step 3), the hydrogenation temperature is 60-160 ℃.
Preferably, in the above process for synthesizing 1, 4-butanediol by using a loop-flow hydrogenation reactor, in step 3), the solvent for hydrogenation is one of methanol, water or tetrahydrofuran.
The invention has the beneficial effects that:
in the aspect of technical improvement:
(1) The process adopts a novel hydrogenation mode of 1, 4-butanediol and a natural gas partial oxidation method, and avoids the environmental pollution caused by hydrogenation by calcium carbide and water.
(2) In the process of preparing acetylene by partial oxidation of natural gas, a screw compressor is used, so that the risk of easy explosion is avoided, and the safety of an experimental device is ensured. .
(3) The yield of the acetylene is improved, and the yield of the 1, 4-butanediol is indirectly increased.
(4) A loop reactor is used, so that 1, 4-butynediol can be subjected to a hydrogenation reaction to generate 1, 4-butanediol, the energy consumption is reduced, and the abrasion of the catalyst is reduced.
(5) The use of Raney nickel catalyst can make the catalytic reaction maximum.
(6) Water is used as a solvent, so that the temperature of the reactor can be effectively reduced, and the activity of the catalyst is ensured.
Social benefit aspect:
(1) The loss of the catalyst is reduced, and the loss of resources and cost caused by continuous replacement of the catalyst is avoided.
(2) The compactness, high efficiency and energy conservation are inevitable and main trends of the development of the current chemical equipment. The airlift loop reactor has no moving parts inside, and the internal fluid is regularly circulated. The device has the advantages of simple structure, low energy consumption, easy large-scale production, convenient operation and the like, and is high-efficiency and energy-saving equipment with application value and development prospect.
(3) The 1, 4-butynediol reactant is better utilized, the 1, 4-butanediol product is generated to the maximum extent, and unnecessary resource waste is avoided.
Partial oxidation of natural gas to produce acetylene → reaction of acetylene and formaldehyde to produce 1, 4-butynediol → hydrogenation of 1, 4-butynediol to produce 1, 4-butanediol. The whole process improves each section on the basis of the traditional acetylenic aldehyde method, improves the purity of the product acetylene in the section of preparing acetylene by partial oxidation of natural gas through an adsorption method, and ensures the safety of the process in the section by using a screw compressor; in the working section of 1, 4-butanediol preparation by hydrogenation of 1, 4-butynediol, the conversion rate of 1, 4-butanediol preparation by hydrogenation of 1, 4-butynediol is improved by using the airlift loop hydrogenation reactor, and through multiple experiments, a Raney nickel catalyst and solvent water are finally selected to improve the reaction yield. The 1, 4-butanediol prepared by the process flow has high purity, and the process is economic and environment-friendly.
Drawings
FIG. 1 is a schematic view of a cracking furnace.
021-mixing chamber; 022-cervical canal; 023-diffusion areas; 024-a combustor; 025-a reaction zone; 026-quench zone.
FIG. 2 is a schematic diagram of a process for the concentration of acetylene.
Fig. 3 is a schematic diagram of a screw compressor two-stage compression system related control configuration.
The labels in the figure are: 01-a first scrubber tank; 02-a primary compressor; 03-first stage compression aftercooler; 04-a second scrubber tank; 05-a secondary compressor; 06-two stage compression aftercooler.
FIG. 4 is a graph of the effect of copper content on catalyst.
FIG. 5 is a graph of the effect of bismuth content on catalyst.
FIG. 6 is a schematic diagram of a loop reactor.
The labels in the figure are: 001-hydrogen feed port; 002-a compressor; 003-membrane; 004-a separator; 005-stirrer; 006-heat exchange tube; a 007-butynediol feed port; 008-a first discharge hole; 009-a second outlet; 010-a hollow tube; 011-jacket; FIG. 7 is a process flow of 1, 4-butanediol production by Reppe method in this project.
The mark in the figure is: 1-a cracking furnace; 2-crude acetylene purification column; 3-an alkynylation reactor; 4-a cooler; 5-a buffer tank; 6-a preheater; 7-a feed pump; 8-low pressure hydrogenation reactor; 9-a buffer tank; 10-a compressor; 11-hydrogen vent condenser; 12-a hydrogen separation tank; 13-two-stage hydrogenation feed pump; 14-second-stage hydrogenation preheater; 15-high pressure hydrogenation reactor; 16-a flash tank; 17-a booster pump; 18-a concentration tower; 19-a booster pump; 20-a salt tower; 21-a thin film evaporator; 22-a condenser; 23-a low-boiling column; 24-a booster pump; 25-high boiling column; 26-a pump; 27 Pump
Detailed Description
The present invention is described in further detail below, but is not to be construed as being limited thereto.
Example 1
The embodiment aims to provide an improved method for applying a circulating hydrogenation reactor to a process for synthesizing 1, 4-butanediol by a Reppe method, which improves the existing 1, 4-butanediol preparation route, and comprises the following specific flows:
partial oxidation of natural gas to produce acetylene → reaction of acetylene and formaldehyde to produce 1, 4-butynediol → hydrogenation of 1, 4-butynediol to produce 1, 4-butanediol.
The reaction flow is shown in fig. 7, oxygen and natural gas are mixed and enter a cracking furnace 1, and crude acetylene is obtained through cracking and purification in a crude acetylene purification tower 2. Acetylene gas is subjected to impurity removal and refining, then mixed with formaldehyde and then enters an ethynylation reactor 3 for ethynylation reaction, unreacted gas at the top end of the reactor enters a cooler 4 for cooling, then enters a buffer tank 5 for separation, and one part of unreacted gas flows back to the ethynylation reactor 3 and the other part of unreacted gas is discharged to a torch system. Reaction liquid at the bottom of the ethynylation reactor 3 enters a low-pressure hydrogenation reactor 8 through a preheater 6 and a feed pump 7, hydrogen firstly enters a buffer tank 9, is compressed by a compressor 10 and then enters the low-pressure hydrogenation reactor 8 to carry out 1, 4-butynediol hydrogenation reaction with the reaction liquid, unreacted gas at the top of the reactor is cooled by a hydrogen emptying condenser 11, enters a hydrogen separation tank 12 to obtain hydrogen, and finally is introduced into the separation tank 9 to recycle the hydrogen. The reaction product obtained from the low-pressure hydrogenation reactor 8 is pressurized by a pressurizing pump 13 and preheated by a preheater 14, and then enters a high-pressure hydrogenation reactor 15, and finally, crude 1, 4-butanediol is obtained. And finally, concentrating the obtained crude 1, 4-butanediol, feeding into a flash tank 16 for flash evaporation, pumping into a concentration tower 18 by a pump 17, separating n-butanol and water from the tower top, and pumping the tower bottom liquid into a salt tower 20 by a pump 19. The high-boiling substance at the bottom of the salt tower 20 enters a film evaporator 21, and the organic substance is evaporated and enters the salt tower 20 again. The gas phase at the top of the salt tower 20 is condensed by a condenser 22 and then enters a low-boiling tower 23, low-boiling-point substances and water are separated out, the liquid at the bottom of the salt tower is pumped into a high-boiling tower 25 by a pump 24, the high-boiling-point substances and the water are removed, and finally the 1, 4-butanediol is obtained. The gas-liquid phase at the top of the high-boiling column is discharged under reduced pressure by pumps 26 and 27, respectively.
The selection of a 1, 4-butanediol process technical route emphasizes comparison and analysis of production principles, process technical sources and characteristics, raw material sources, technical economy and other aspects, and a novel alkyne-aldehyde method production process is adopted by combining the energy policy and local resource conditions in China, the raw material resource advantages of construction units, product structures, scale sizes, investment and other factors.
Reaction section 1 partial oxidation of natural gas to acetylene
Natural gas is a multi-component mixed gaseous fossil fuel that is found primarily in oil, gas, coal and shale fields, with the main component being alkanes, the majority of which is methane, and small amounts of ethane, propane and butane.
The working section of the acetylene preparation by partial oxidation of natural gas is that natural gas and oxygen respectively enter a cracking furnace, the structure of the cracking furnace is shown in figure 1, and the cracking furnace mainly comprises a mixing chamber 021, a neck pipe 022, a diffusion zone 023, a burner 024, a hearth 025 and a quenching zone 026. The natural gas and oxygen are mixed in a mixing chamber 021, which is a cylinder with a float inside. In the mixing zone, the natural gas flows through the annular section and oxygen is blown into the natural gas via both sides of the gas flow for mixing. The exit velocity of the mixture is greater than 50m/s and passes from neck 022 through diffusion zone 023 to combustor 024. The burner has two annular flow channels, 6 guide blocks in each channel for the fluid vortex, and an exit velocity of the methane-oxygen mixture of greater than 300m/s. To prevent the flame from blowing out, a small portion of stabilized oxygen is fed into the burner to sustain the reaction. And then into reaction zone 025 where a flame reaction of partial oxidation of natural gas and cracking of methane occurs to produce acetylene and other reaction products. In order to ensure the yield of acetylene and minimize the decomposition of acetylene. The gas exiting the reaction zone 025 is immediately sprayed by the lower quench zone 026Quenching water is added to quench the reaction to 89 ℃, thereby stopping the reaction, and quenched gas is sent out from the lower part of a quenching zone 026 and enters the next section for continuous reaction. However, in this stage, the acetylene gas produced contains a large amount of impurities, and therefore, a purification treatment of the gaseous product is required. We plan to use an adsorption process to refine acetylene as shown in figure 2. In the pressure and temperature varying adsorption system, the adsorption beds are used for circular adsorption and regeneration, active carbon is used mainly to adsorb higher alkyne in acetylene material gas, and the higher alkyne may be fed to power station as fuel. Then acetylene is absorbed by an acetylene absorption device to leave H 2 And CO, which can be used as synthesis gas. And the acetylene is retained in the adsorption bed layer, is discharged out of the system and enters the next working section for continuous reaction.
In addition, the raw material natural gas adopted by the process is extremely easy to burn and has strong explosion danger when being contacted with pure oxygen at high temperature; the cracking gas containing acetylene is generated in the partial oxidation process, the high-grade alkyne gas containing a large amount of diacetylene is generated in the concentration process, and the acetylene product is easy to explode.
As shown in table 1, the decomposition pressures for acetylene and higher alkynes are relatively low. When the partial pressure is high, acetylene and higher alkyne are easy to be explosively decomposed, so that the partial pressure of acetylene is strictly controlled below 0.14MPa when pyrolysis gas is compressed, and therefore, the pressure of a back pressure pipeline and a concentration process is strictly controlled below 1.08 MPa. Under the condition of high temperature, acetylene and high-grade alkyne in the pyrolysis gas are easy to polymerize, and the pyrolysis gas often contains polymer and carbon black, so that the pyrolysis gas compression device adopts a screw compressor, the structure of which is shown in figure 3, the pyrolysis gas firstly enters a first scrubbing tank 101 for processing, and then enters a first-stage compressor 102, and the main technical parameter is that the first-stage processing capacity is 25 multiplied by 104m 3 The first-stage compression air inlet pressure is 30kPa (G), the exhaust pressure is 850kPa (G), the first-stage compression air inlet temperature is 40 ℃, and the exhaust temperature is 85 ℃; the compressed gas enters a first-stage compressor cooler 103 for cooling treatment and then enters a second-stage compressor 105 through a second scrubbing tank 104, and the main technical parameters are that the second-stage treatment capacity is 15 multiplied by 104m 3 D, the pressure of the secondary compression inlet air is 800kPa (G), the exhaust pressure is 2400kPa (G), the temperature of the secondary compression inlet air is 40 ℃, and the exhaust is carried outThe gas temperature was 85 ℃. The compressed gas enters the secondary compressor cooler 106 for cooling and then is discharged. Meanwhile, in order to prevent the screw compressor from reversing, reduce the starting torque and the bearing load and balance the inlet and outlet pressure as soon as possible when the compressor is stopped, an unloading valve with high reaction speed is additionally arranged to realize two balance, one discharge and two return flows. The pipeline provided with the unloading valve is connected to the inlet of the compression outlet pipeline of each stage, and the discharge valve is arranged at the outlet of the secondary compressor to ensure the safe discharge of the whole compressor system.
The screw compressor has the characteristics of low compression ratio and two-stage compression, desalted water is adopted in the compressor as jet water, and the outlet temperature of each stage is controlled to be below 80 ℃, so that the polymerization of acetylene and high-grade alkyne is reduced; and the interstage is sprayed and cooled by carbon black water, the temperature is controlled to be about 35 ℃, if the temperature is controlled to be too low, the polymer can be crystallized to block a backpressure pipeline, so that the flow rate of the cracked gas is too high, the pressure of the pipeline is increased, and the safety of the device is endangered.
Table 1: decomposition pressure of acetylene and higher alkynes
Name(s) Decomposition pressure/MPa
C 2 H 2 (acetylene) 0.14
M-C 3 H 4 (Methylacetylene) 0.18
C 4 H 4 (vinyl acetylene) 0.11
C 4 H 2 (diacetylene) 0.02
In the process flow of preparing acetylene from natural gas, acetylene gas generated in the cracking and concentration processes contains a lot of impurities, so that the gas product needs to be subjected to impurity removal treatment. The impurity removal of acetylene gas is mainly divided into two steps: purifying and refining acetylene. The purification is mainly to remove most of the impurities present in the acetylene, while the purification of acetylene is to remove a small amount of higher alkynes mixed in the acetylene. If the acetylene obtained is to be used as a starting material for the synthesis of 1, 4-butynediol, the purity is at least 99.5%.
The conventional acetylene refining method is mainly an acid-base refining method, and although the acid-base refining method can obtain the acetylene product reaching the standard, the method has the problems of high acid-base consumption, difficulty in treating waste acid, waste residue formation by high-grade alkyne polymerization and the like. Therefore, it is planned to purify acetylene by an adsorption method. In the pressure-swing temperature-change adsorption system, each adsorption bed is subjected to cyclic adsorption and regeneration, and the high-grade alkyne in the acetylene feed gas is mainly adsorbed by adopting active carbon and is retained in the adsorption bed layer to obtain purified acetylene gas which is then discharged out of the system. The purity of the purified gas is more than 99.4 percent, and the recovery rate of the acetylene is more than 99.5 percent.
Reaction section 2 acetylene and formaldehyde react to prepare 1, 4-butynediol
Acetylene and formaldehyde prepared by partial oxidation of natural gas are subjected to an ethynylation reaction in a slurry reactor under the catalysis of a copper bismuth catalyst with the copper content of 20% and the bismuth content of 4% to generate 1, 4-butynediol, and the 1, 4-butynediol obtained by impurity removal enters the next hydrogenation section for reaction.
The industrial production of 1, 4-butynediol by using the copper bismuth catalyst is carried out on a slurry bed reactor, the slurry reactor uses a stirred tank reactor, slurry is mixed by adopting mechanical stirring, and the method is suitable for occasions with high solid content, small gas flow or intermittent feeding of both gas phase and liquid phase, and can continuously discharge inactivated catalyst; the liquid has large liquid loading amount and good heat transfer, mass transfer and mixing performance; the conditions are mild.
The copper bismuth catalyst used in the reaction process of generating 1, 4-butynediol by the reaction of acetylene and formaldehyde can ensure the catalytic reaction to the maximum extent and accelerate the reaction rate. The copper bismuth content of the catalyst was analyzed to discuss the most suitable copper bismuth catalysts.
0.7g of a copper-bismuth catalyst (bismuth content: 4%) and 35ml of a 4.0% formaldehyde solution were charged into the reaction vat, and the formaldehyde conversion and the 1, 4-butynediol yield were observed under conditions of an acetylene partial pressure of 0.88MPa, a temperature of 90 ℃ and a rotation speed of 600 r/min.
Table 2: influence of copper content on the catalyst
Copper content/%) Conversion of formaldehyde/% 1,4 butynediol yield%
15 88.14 73.30
20 91.20 80.30
25 87.53 70.50
30 89.16 65.60
35 87.22 58.60
The results of the effect of copper content on the catalyst are shown in FIG. 4.
0.7g of a copper-bismuth catalyst (copper content: 20%) and 35ml of a 4.0% formaldehyde solution were charged into the reaction vat, and the formaldehyde conversion and the 1, 4-butynediol yield were observed under conditions of an acetylene partial pressure of 0.88MPa, a rotation speed of 600r/min and a temperature of 90 ℃.
Table 3: effect of bismuth content on the catalyst
Figure BDA0003832092810000071
Figure BDA0003832092810000081
The effect of bismuth content on the catalyst results are shown in fig. 5.
During the reaction of synthesizing 1, 4-butynediol from formaldehyde and acetylene, the side reaction of acetylene polymerization is easy to occur, carbon deposition is formed on the surface of the catalyst, and the catalyst is inactivated. The addition of bismuth can improve the activity and selectivity of the catalyst, and has stronger carbon deposition resistance, thereby inhibiting the generation of polyacetylene. As can be seen from the figure, addition of Bi at less than 4% is advantageous in increasing the activity and selectivity of the catalyst, but the increase is not so great, and the yield of 1, 4-butynediol begins to decrease when the Bi content exceeds 4%.
Therefore, the maximum activity of the catalyst can be exhibited by selecting a copper content of 20% and a bismuth content of 4%.
Reaction section 3, 4-butynediol hydrogenation for preparing 1, 4-butanediol
The 1, 4-butynediol produced flows out of the slurry bed and is subjected to hydrogenation. The airlift loop reactor is planned to be applied to a hydrogenation working section, and has the advantages of simple structure, good fluid mechanical property and easy engineering amplification. As shown in fig. 6, the loop reactor is a multi-phase reactor which is more efficient than the bubble bed reactor and has better mass and heat transfer effects in the reactor, because a guide cylinder is added on the basis of the bubble bed reactor, the fluid in the reactor flows in a regular loop along the guide cylinder. Loop reactors also have advantages over other reactors having complex structures. The airlift loop reactor is a novel reactor improved from a bubbling reactor, integrates the performances of a bubbling bed and a stirring kettle, and has the advantages of simple structure, no mechanical rotating part, uniform shearing force field, low energy consumption, high energy efficiency and the like.
First, 1, 4-butynediol was fed from butynediol feed inlet 007, and hydrogen was fed from hydrogen feed inlet 001. 1, 4-butynediol moves downwards under the action of gravity, hydrogen enters from a hydrogen inlet 001, and is accumulated above the reactor because the hydrogen is much lower in density than air, so that the hydrogen is compressed by an upper compressor 002 to form a downward airflow, and after the hydrogen overflows from the hollow pipe, the hydrogen forms an upward airflow due to the low density. The 1, 4-butynediol moving downwards and the hydrogen moving upwards are fully mixed and completely react through a magnetic stirrer, and the prepared product flows out from the second material outlet 009. Because the hydrogen is sufficient, in order to recycle the hydrogen, the diaphragm 003 is arranged below the compressor 002, the hydrogen and impurities are separated for the first time, and substances entering the diaphragm 003 are separated for the second time through the separator 004, so that pure hydrogen is finally obtained. The purified hydrogen obtained from the recycle is compressed by the compressor 002 together with the feed hydrogen to form a downward gas flow again, and finally the hydrogen is made to form a circular flow in the reactor. The hollow shaft 010 is surrounded by the heat exchange tubes 006, the heat exchange tubes 006 are in a spiral form, a certain distance is reserved between the heat exchange tubes 006 and the hollow shaft 010, material conversion is not affected, and heat transfer and heat exchange effects can be achieved.
In the hydrogenation process of 1, 4-butynediol, raney nickel is selected as a catalyst for the reaction:
table 4: effect of different catalysts on 1, 4-butynediol hydrogenation Performance
Reaction conditions:1g BYD,0.1gcat，20mlMeOH,120℃，2MPa，2h
Figure BDA0003832092810000091
As shown in Table 4, raney nickel, raney cobalt, raney iron, raney copper, pd/C, ru/C can be used as catalysts for the hydrogenation of 1, 4-butynediol. As can be seen from the data in the table, the conversion rate can reach 100% by using the Raney-Ni based catalyst, the selectivity of BDO is 76.2%, and the hydrogenation effect is the best.
The raw material of Raney-Ni is Ni-Al alloy, and the preparation method and the process of the alloy are shaped. The preparation method of the powdery Raney nickel catalyst comprises the following steps: under the protection of argon, heating and melting the solid powder of Ni and Al in a specific ratio to obtain a uniform alloy. After cooling to room temperature, the nickel-aluminum alloy is crushed, and the nickel-aluminum alloy block is ground into nickel-aluminum alloy powder by using a ball mill. 10g of nickel-aluminum alloy powder was slowly added to 50mL of 20% (wt) sodium hydroxide solution in portions, and stirred at 90 ℃ for 1 hour. After activation, the catalyst is washed to be neutral by deionized water, and the activated catalyst is placed in water for storage so as to maintain the activity of the catalyst. The preparation method of the amorphous Raney nickel catalyst comprises the following steps: 15g of the nickel-aluminum alloy block was put into a reaction tube, and 25% (wt) of a sodium hydroxide solution was introduced at a flow rate of 0.5mL/min to react at 50 ℃ for 2 hours. After activation, washing the catalyst to be neutral by using deionized water to obtain the amorphous Raney nickel catalyst which can be used for subsequent reaction.
In the hydrogenation process of 1, 4-butynediol, water is used as a solvent for reaction to achieve the effect of reducing the temperature:
as the hydrogenation of 1, 4-butynediol to prepare 1, 4-butanediol is a strong exothermic reaction, the reaction heat is 251kJ/mol, the reaction is favorably carried out by heating within a certain temperature range, but side reactions can occur due to overhigh temperature, and the yield is even influenced. Experiments were carried out at 60 deg.C, 80 deg.C, 100 deg.C, 120 deg.C, 140 deg.C and 160 deg.C to examine the effect of temperature on selective hydrogenation of 1, 4-butynediol. The results are shown in Table 5.
Table 5: effect of different reaction temperatures on the hydrogenation of 1, 4-butynediol
Reaction conditions:0.1g cat.,1g BYD,100℃，2MPa，2h
Figure BDA0003832092810000092
Figure BDA0003832092810000101
At the reaction temperature of 100 ℃, the Raney nickel catalyst has the best catalytic performance, the conversion rate of BYD is 100%, and the selectivity of BDO is 90.6%. As the reaction temperature increased, the BYD conversion tended to plateau and then decrease, while the BDO selectivity tended to increase and then decrease. Since the BYD hydrogenation reaction belongs to an exothermic reaction, increasing the reaction temperature in a certain range has a promoting effect on the reaction process, but the reaction temperature is too high to promote side reactions, which reduces the reaction conversion rate and selectivity. In conclusion, the reaction temperature of 100 ℃ is selected to be suitable. Therefore, the reaction solvent is utilized, so that the temperature of the reactor is not too high when the reaction occurs, and the conversion rate and the selectivity are ensured. The results of the effect on the hydrogenation of 1, 4-butynediol when methanol, tetrahydrofuran and water were selected as the reaction solvent are shown in Table 6.
TABLE 6 influence of the solvent on the hydrogenation behavior of Raney's nickel catalyst for 1, 4-butynediol
Reaction conditions:0.1g cat.,1g BYD,100℃，2MPa，2h
Figure BDA0003832092810000102
As shown in the table, methanol, water and tetrahydrofuran were used as the solvents for the hydrogenation of 1, 4-butynediol, respectively. As can be seen from the data in the table, the selectivity of 1, 4-butanediol was minimal when tetrahydrofuran was used as the solvent, probably due to the greater steric hindrance of the solvent, which was detrimental to BDO formation. When water is used as a solvent, the selectivity of 1, 4-butanediol is the highest, and the selectivity is 90.6%. This is because free hydrogen exists in water, which has good ability to transfer hydrogen atoms and supply hydrogen, and can improve reaction rate and product selectivity. Meanwhile, water is used as a solvent, so that the cost is lower, the safety is higher, and the environment is more friendly. Taking comprehensive consideration, water is selected as a reaction solvent. The yield is not influenced, and the effect of cooling is achieved.

Claims (11)

1. A process for applying a circulating hydrogenation reactor to synthesis of 1, 4-butanediol by a Reppe method is characterized by comprising the following steps:
1) Partial oxidation of natural gas to acetylene: respectively feeding natural gas and oxygen into a cracking furnace, cracking at 1800 ℃, separating and concentrating to obtain crude acetylene gas;
2) Acetylene and formaldehyde react under the condition of a catalyst to prepare 1, 4-butynediol, and impurities are removed;
3) 1, 4-butanediol is prepared by hydrogenating 1, 4-butynediol under the condition of a catalyst.
2. The process for synthesizing 1, 4-butanediol by applying the cycloidal hydrogenation reactor to the Reppe process according to claim 1, characterized in that the step 1) further comprises impurity removal treatment, wherein the impurity removal treatment comprises purification and refining of acetylene, and the refining is to use activated carbon to adsorb higher alkyne in acetylene feed gas.
3. The process for synthesizing 1, 4-butanediol by applying the loop current hydrogenation reactor to the Reppe method according to claim 1, wherein the catalyst in the step 2) is a copper bismuth catalyst.
4. The process for synthesizing 1, 4-butanediol by applying the loop current hydrogenation reactor to the Reppe method according to claim 1, characterized in that the gas lift loop reactor is used for hydrogenation in the step 3).
5. The process for synthesizing 1, 4-butanediol by applying the loop current hydrogenation reactor to the Reppe method according to claim 1, wherein the airlift loop reactor has a structure that: airlift loop reactor upper end top intermediate position is equipped with hydrogen feed inlet (001), hydrogen feed inlet (001) below is equipped with compressor (002), compressor (002) in proper order with diaphragm (003), separator (004) are connected, separator (004) below is equipped with hollow tube (010), hollow tube (010) extend to the bottom that is close airlift loop reactor, airlift loop reactor upper end top still is equipped with butynediol feed inlet (007), airlift loop reactor inside still is equipped with agitator (005) and heat exchange tube (006), airlift loop reactor side upper portion and lower part are equipped with first discharge gate (008) and second discharge gate (009) respectively.
6. The process of claim 1, wherein the catalyst used in step 3) is one or more of raney nickel, raney cobalt, raney iron, raney copper, pd/C, and Ru/C.
7. The process of claim 6, wherein the catalyst used in step 3) is Raney nickel catalyst, and the Raney nickel catalyst is powdered Raney nickel catalyst or amorphous Raney nickel catalyst.
8. The process for synthesizing 1, 4-butanediol by applying a circulating hydrogenation reactor to a Rapper's method according to claim 7 is characterized in that the preparation method of the powdery Raney nickel catalyst comprises the following steps of heating and melting solid powder of Ni and Al under the protection of argon to obtain uniform nickel-aluminum alloy, cooling to room temperature, crushing, ball-milling to obtain nickel-aluminum alloy powder, slowly adding the nickel-aluminum alloy powder into a sodium hydroxide solution in batches, activating, washing to be neutral after activation is completed, and placing in water for storage.
9. The process of claim 7, wherein the amorphous Raney nickel catalyst is prepared by placing a nickel-aluminum alloy block in a reaction tube, introducing 25 wt% sodium hydroxide solution at a flow rate of 0.5mL/min, reacting at 50 ℃ for 2h, and washing to neutrality after activation.
10. The process for synthesizing 1, 4-butanediol by applying the circulating hydrogenation reactor to the Reppe method according to claim 1, wherein the hydrogenation temperature in the step 3) is 60-160 ℃.
11. The process of claim 1, wherein the solvent used in hydrogenation step 3) is one of methanol, water and tetrahydrofuran.
CN202211077299.1A 2022-09-05 2022-09-05 Process for synthesizing 1, 4-butanediol by applying loop current hydrogenation reactor to Reppe method Pending CN115448815A (en)

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