Alkyne C4 selective hydrogenation method for improving butylene-1 selectivity

Abstract

The invention belongs to the field of petrochemical industry, and relates to an alkyne C4 selective hydrogenation method for improving butylene-1 selectivity. Comprising the following steps: (1) feeding an alkyne-containing C4 raw material, hydrogen and a solvent into a hydrogenation reactor, and carrying out a selective hydrogenation reaction under the action of a catalyst to obtain a material after the hydrogenation reaction; the flow ratio of the alkyne-containing C4 raw material to the hydrogen is (20-50): 1; (2) the material after hydrogenation reaction enters a gas-liquid separation tank for gas-liquid separation, hydrogenated liquid-phase C4 is obtained, one part of the hydrogenated liquid-phase C4 serves as a circulating material 1, and the other part of the hydrogenated liquid-phase C4 enters a rectifying tower; and (3) the hydrogenated liquid-phase C4 entering the rectifying tower is rectified in the rectifying tower, a product C4 is obtained through tower top separation, a circulating material 2 is obtained in a tower kettle, the circulating material 1 and the circulating material 2 are mixed to obtain a total circulating material, and the total circulating material is cooled and then returned to an inlet of the hydrogenation reactor. The conversion rate of alkyne and alkadiene reaches 80% or above, and the selectivity of 1-butene reaches 50% or above.

Description

Technical Field

[0001] This invention belongs to the field of petrochemicals, and specifically relates to a method for selective hydrogenation of alkynes C4 to improve the selectivity of butene-1. Background Technology

[0002] 1,3-Butadiene is an important chemical raw material and a major raw material for the production of synthetic rubber and resins. Currently, butadiene is mainly obtained through extraction from C4 cracking in ethylene plants. Simultaneously, alkynes from the cracked C4 are enriched during extraction, forming C4-acetylene tail gas. This C4-acetylene tail gas is rich in vinylacetylene and ethylacetylene, with vinylacetylene content generally exceeding 20 wt%, and sometimes exceeding 40 wt%. Due to the self-decomposition and explosive hazard of vinylacetylene, this C4-acetylene tail gas is typically diluted with C4 raffinate and used as fuel, or incinerated via a flare, resulting in a waste of C4 resources. Currently, the main industrial approach to recover and utilize this alkyne-rich C4 resource is through hydrogenation, converting it into high-value-added products, which offers significant economic and social benefits.

[0003] The main components of C4-acetylenes are: butene-1, isobutene, butene-2, 1,3-butadiene, 1,2-butadiene, ethylacetylene, and vinylacetylene. Among these, 1,3-butadiene, 1,2-butadiene, ethylacetylene, and vinylacetylene can all react with hydrogen to produce 1-butene. 1-Butene is a chemically reactive α-olefin, which can be used as a comonomer for LLDPE and a polymer monomer for poly1-butene, and is also an important raw material for the production of isooctene, butanone, and other chemical products. Under the presence of alkynes, dienes, and hydrogen, and in the presence of a catalyst, alkynes and dienes are hydrogenated to produce 1-butene. 1-Butene readily undergoes further hydrogenation to form butane, thus reducing reaction selectivity and the yield of 1-butene. Therefore, by rationally controlling the reaction depth through process techniques to inhibit the further hydrogenation of 1-butene to butane, the economic value of C4-acetylene hydrogenation products can be effectively improved.

[0004] CN102285859B discloses a selective hydrogenation process for a C4 stream with high butadiene content. This patent involves passing a C4 stream containing a high concentration of butadiene through one or more fixed-bed hydrogenation reactors with recirculation lines. The C4 mixture containing high butadiene undergoes selective hydrogenation under the action of a catalyst, removing butadiene and alkynes to produce butene. The stream then passes through a terminal reactor without recirculation lines to further remove remaining butadiene and alkynes from the C4 stream containing a low concentration of butadiene. This method employs a two-stage hydrogenation process to produce butene-1 as the target product. However, using the hydrogenated product as a recirculation stream may result in a loss of selectivity.

[0005] CN114478176B discloses a selective hydrogenation device and method for butadiene extraction tail gas. This patent includes a feed tank, a feed pump, a coalescer, a primary mixer, a primary reactor, a primary reactor outlet buffer tank, a secondary feed cooler, a secondary mixer, a secondary reactor, a secondary reactor outlet buffer tank, and a stabilizer. The outlet pipeline of the primary reactor outlet buffer tank is divided into two paths: the first path connects sequentially to the circulating C4 cooler, the primary mixer, and the primary reactor; the second path connects to the secondary feed cooler. The hydrogen feed pipeline is divided into at least a first stream and optionally a second and a third stream. The first stream connects to the primary reactor outlet buffer tank, the second stream connects to the secondary mixer, and the third stream connects to the primary mixer. This method requires a two-stage hydrogenation reactor, making the process complex.

[0006] CN115710153A discloses a flexible method and apparatus for hydrogenating C4 acetylene. The process includes steps such as pressurization, liquefaction, water washing for impurity removal, dehydration, hydrogenation, and separation. It can achieve three types of C4 acetylene-rich hydrogenation reaction processes and can treat tail gas containing acetylene and impurities from butadiene plants. In this process, impurities requiring water washing to remove include water-soluble solvents and water-soluble polar organic compounds, such as N-methylpyrrolidone. However, the recycling of reaction products as a means of removing reaction heat inevitably leads to excessively long product residence times, resulting in secondary reactions and difficulty in ensuring high selectivity. Furthermore, the pretreatment process is complex, energy-intensive, and generates a large amount of waste pollutants. Summary of the Invention

[0007] The purpose of this invention is to address the aforementioned problems in the prior art and provide a C4 selective hydrogenation method for alkynes to improve the selectivity of 1-butene. Under the action of a catalyst, C4 alkynes undergo a hydrogenation reaction with hydrogen. By controlling the depth of hydrogenation, a large amount of alkynes can be converted into 1-butene. This invention uses a mixture of hydrogenation product and circulating solvent as the circulating stream to remove the heat of reaction. The circulating solvent enriches the alkynes and dienes that can be converted into 1-butene in the circulating solvent, and they preferentially adsorb onto the catalyst surface for reaction, thereby increasing the concentration of alkynes and dienes on the catalyst surface and promoting the conversion rate and selectivity of alkynes and dienes. For C4 feedstock with an alkyne content of 20-30%, the conversion rate of alkynes and dienes can reach over 80%, and the 1-butene selectivity can reach over 50%. The product can be used as feedstock for butadiene extraction units, increasing the production of residual C4, improving the conversion rate and selectivity of the hydrogenation reaction, and effectively improving the utilization rate of C4 resources.

[0008] To achieve the above objectives, the present invention provides a method for selective hydrogenation of alkynes with C4-selective hydrogenation to improve butene-1 selectivity, comprising the following steps:

[0009] (1) Alkyne-containing C4 feedstock, hydrogen and solvent are fed into a hydrogenation reactor and selectively hydrogenated under the action of a catalyst to obtain the hydrogenated material; the flow ratio of the alkyne-containing C4 feedstock to hydrogen is 20 to 50:1.

[0010] (2) The material after the hydrogenation reaction enters the gas-liquid separator for gas-liquid separation to obtain hydrogenated liquid C4. The hydrogenated liquid C4 is divided into two parts, one part is used as circulating material 1, and the other part enters the distillation column.

[0011] (3) The hydrogenated liquid C4 entering the distillation column is distilled in the distillation column. The product C4 is separated at the top of the column, and the recycled material 2 is obtained at the bottom of the column. The recycled material 1 and recycled material 2 are mixed to obtain the total recycled material, which is cooled and returned to the inlet of the hydrogenation reactor.

[0012] The apparatus and method of this invention use a mixture of circulating solvent and part of the hydrogenation product as a circulating reaction heat carrier. On the one hand, this reduces the residence time of the reaction products in the reactor bed due to circulation. On the other hand, compared with butane and isobutane, the introduced circulating solvent has better solubility for the reaction raw materials alkynes and dienes. Therefore, the alkynes and dienes dissolved in the circulating solvent are more likely to undergo selective hydrogenation on the catalyst surface due to concentration enrichment. After generating 1-butene, they are more likely to desorb from the catalyst surface due to solubility, thus greatly improving the selectivity of the reaction.

[0013] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0014] Exemplary embodiments of the present invention will be described in more detail with reference to the accompanying drawings.

[0015] Figure 1 A process flow diagram of the alkyne C4 selective hydrogenation method for improving butene-1 selectivity according to the present invention is shown.

[0016] Explanation of reference numerals in the attached figures

[0017] I: Fixed-bed reactor; II: Vapor-liquid separator; III: Distillation column.

[0018] 1. Hydrogen, 2. Alkyne C4, 3. Hydrogenated low-alkyne C4, 4. Hydrogenated liquid C4, 5. C4 entering the distillation column, 6. Total recycled material, 7. Product C4, 8. Recycled material 2, 9. Solvent, 10. Discharge solvent. Detailed Implementation

[0019] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0020] To achieve the above objectives, the present invention provides a method for selective hydrogenation of alkynes with C4-selective hydrogenation to improve butene-1 selectivity, comprising the following steps:

[0021] (1) Alkyne-containing C4 feedstock, hydrogen and solvent are fed into a hydrogenation reactor and selectively hydrogenated under the action of a catalyst to obtain the hydrogenated material; the flow ratio of the alkyne-containing C4 feedstock to hydrogen is 20 to 50:1.

[0022] (2) The material after the hydrogenation reaction enters the gas-liquid separator for gas-liquid separation to obtain hydrogenated liquid C4. The hydrogenated liquid C4 is divided into two parts, one part is used as circulating material 1, and the other part enters the distillation column.

[0023] (3) The hydrogenated liquid C4 entering the distillation column is distilled in the distillation column. The product C4 is separated at the top of the column, and the recycled material 2 is obtained at the bottom of the column. The recycled material 1 and recycled material 2 are mixed to obtain the total recycled material, which is cooled and returned to the inlet of the hydrogenation reactor.

[0024] According to the present invention, preferably, the alkyne C4 selective hydrogenation method is carried out using an alkyne C4 selective hydrogenation device, which includes a hydrogen feed line, an alkyne C4 feed line, a solvent feed line, a hydrogenation reactor, a gas-liquid separator, and a distillation column.

[0025] The hydrogen feed line and solvent feed line merge, and then merge with the alkyne C4 feed line, and then connect in sequence to the hydrogenation reactor, gas-liquid separator and distillation column;

[0026] The liquid phase discharge pipeline of the gas-liquid separator is divided into two branches, one of which serves as the circulating material pipeline 1, and the other is connected to the distillation column.

[0027] The distillation column is equipped with a top discharge pipeline and a bottom discharge pipeline. The bottom discharge pipeline serves as a circulating material pipeline 2. The circulating material pipeline 1 and the circulating material pipeline 2 are connected to the inlet of the hydrogenation reactor after they merge.

[0028] A cooler is installed on the merging pipeline of circulating material pipeline 1 and circulating material pipeline 2.

[0029] According to the present invention, preferably, the merging pipeline of the circulating material pipeline 1 and the circulating material pipeline 2 first merges with the hydrogen feed pipeline, then merges with the alkyne C4 feed pipeline, and then connects to the inlet of the hydrogenation reactor; a gas-liquid mixer is provided on the pipeline connected to the inlet of the hydrogenation reactor.

[0030] According to the present invention, preferably, the distillation column is a plate column or a packed column, and more preferably selected from at least one of floating valve plate column, solid valve plate column, structured packed column and random packed column.

[0031] According to the present invention, preferably, both the circulating material pipeline 1 and the circulating material pipeline 2 are provided with flow regulating valves.

[0032] According to the present invention, preferably, the mass flow rate ratio of the circulating material 1 to the circulating material 2 is 0.1 to 50:1, more preferably 0.1 to 40:1.

[0033] According to the present invention, preferably, the ratio of the total circulating material to the mass flow rate of the alkyne-containing C4 feedstock is 0.1 to 80:1, more preferably 10 to 60:1.

[0034] Preferably, the solvent accounts for 0.1% to 90% of the total recycled material, and more preferably 40% to 90%.

[0035] According to the present invention, preferably, the total circulating material is cooled to 30-50°C by a cooler before being returned to the inlet of the hydrogenation reactor.

[0036] According to the present invention, preferably, the operating conditions of the hydrogenation reaction include: a reaction temperature of 5 to 100°C, more preferably 20 to 80°C, and a reaction pressure of 0.6 to 5.0 MPaG.

[0037] According to the present invention, preferably, the operating conditions of the distillation column are as follows: the number of trays is 5 to 60, the feed position is the 15th to 25th tray, the column pressure is 0.1 to 0.6 MPaG, the column top temperature is 5 to 60°C, and the column bottom temperature is 150 to 350°C.

[0038] In this invention, the reaction can be carried out using selective hydrogenation catalysts known in the art, preferably the selective hydrogenation catalyst disclosed in CN102240547. The catalyst preferably comprises the following components by weight: palladium in a content of 0.015 to 2.00 wt%, one or more auxiliary metals selected from lead, silver, tin, magnesium and calcium in a content of 0.005 to 3.0 wt%; and the balance is a support selected from at least one support selected from alumina, titanium oxide and magnesium oxide.

[0039] According to the present invention, preferably, the circulating solvent is N-methylpyrrolidone.

[0040] In this invention, compared with butene-1 and butadiene, the introduced solvent has better solubility for the reaction raw material vinylacetylene. Therefore, vinylacetylene dissolved in the solvent is more likely to undergo selective hydrogenation on the catalyst surface due to its concentration enrichment. After generating butadiene, it is more likely to desorb from the catalyst surface due to its solubility, thus greatly improving the selectivity of the reaction.

[0041] According to the present invention, preferably, the alkyne-containing C4 raw material comprises C2 to C4. 10At least one of the light hydrocarbon feedstocks.

[0042] Preferably, based on the total weight of the C4 raw material containing alkynes, the content of alkynes in the C4 raw material is 0.0001 to 40 wt%.

[0043] The present invention will be further described below with reference to the embodiments, but the scope of the present invention is not limited to these embodiments.

[0044] Example 1

[0045] This embodiment uses, as follows: Figure 1 The C4 alkyne selective hydrogenation unit shown includes a hydrogen feed line, a C4 alkyne feed line, a solvent feed line, a fixed-bed reactor I, a gas-liquid separator II, and a distillation column III; wherein the distillation column is a valve plate column.

[0046] The hydrogen feed line, alkyne C4 feed line, and solvent feed line converge and are then connected in sequence to the hydrogenation reactor, gas-liquid separator, and distillation column.

[0047] The liquid phase discharge pipeline of the gas-liquid separator is divided into two branches, one of which serves as the circulating material pipeline 1, and the other is connected to the distillation column.

[0048] The distillation column is equipped with a top discharge line and a bottom discharge line. The bottom discharge line serves as the circulating material line 2. After the circulating material lines 1 and 2 merge, the merging line first merges with the hydrogen feed line, then with the alkyne C4 feed line, and then connects to the inlet of the hydrogenation reactor. A gas-liquid mixer is installed on the line connected to the inlet of the hydrogenation reactor.

[0049] Both circulating material pipeline 1 and circulating material pipeline 2 are equipped with flow regulating valves, and a cooler is installed on the confluence pipeline of circulating material pipeline 1 and circulating material pipeline 2.

[0050] Liquefied butadiene tail gas 2 from the butadiene extraction unit, temperature 25℃, flow rate 1700 kg / h. Circulating stream 6, temperature 40℃, flow rate 50000 kg / h. Hydrogen gas 1 is thoroughly mixed with the circulating solvent N-methylpyrrolidone, and then mixed with liquefied butadiene tail gas 2. Hydrogen temperature 25℃, flow rate 45 kg / h.

[0051] The reactor operating conditions are: 2.0 MPaG, inlet temperature 39℃, and outlet temperature 66℃. The reactor outlet stream is sent to a vapor-liquid separator. After vapor-liquid two-phase equilibrium separation, the vapor flow rate is 0 kg / h, and the liquid flow rate is 517,450 kg / h. 30,000 kg / h of the liquid phase is returned to the reactor inlet as a recirculating stream; 21,745 kg / h of the liquid phase is sent to a distillation column.

[0052] The distillation column is a valve tray type with 36 trays, and the feed is fed onto the 20th tray. The operating temperature at the top is 20℃, the operating temperature at the bottom is 184.0℃, the operating pressure at the top is 0.6 MPaG, the operating pressure at the bottom is 0.65 MPaG, and the reflux ratio is 2.0. The distillation column separates the C4 hydrogenation product from the circulating solvent N-methylpyrrolidone. The circulating solvent in the bottom is cooled to 40℃ and then returned to the reactor inlet to be mixed again with the butadiene tail gas. The output of non-condensable vapor from the top is 3.86 kg / h, the output of liquid C4 hydrogenation product from the top is 1650 kg / h, and the output of circulating solvent from the bottom is 20091.14 kg / h.

[0053] The catalyst loaded in the reactor is supported on alumina and contains active metallic components such as palladium, lead, and silver.

[0054] The quality composition of each major logistics item is shown in Table 1.

[0055] Table 1

[0056]

[0057] The selectivity of 1-butene is defined as follows:

[0058]

[0059] The above 1-butene, alkynes and dienes are calculated in kmol / h.

[0060] As shown in Table 1, the mass fraction of 1-butene in the hydrogenated product is 35.18%, the mass fraction of 1-butene in the feedstock is 19.16%, the selectivity of 1-butene is 51.18%, and the conversion rate of alkynes and dienes is 88.81%.

[0061] Example 2

[0062] Liquefied butadiene tail gas 2 from the butadiene extraction unit, temperature 25℃, flow rate 1700 kg / h. Circulating stream 6, temperature 30℃, flow rate 46500 kg / h. Hydrogen 1 is thoroughly mixed with the circulating solvent N-methylpyrrolidone, and then mixed with liquefied butadiene tail gas 2. Hydrogen temperature 25℃, flow rate 60 kg / h.

[0063] The reactor operating conditions were: 2.0 MPaG, inlet temperature 29℃, and outlet temperature 57℃. The reactor outlet stream was fed into a vapor-liquid separator. After vapor-liquid two-phase equilibrium separation, the vapor flow rate was 21.12 kg / h, and the liquid flow rate was 48739.05 kg / h. 45000 kg / h of the liquid phase was returned to the reactor inlet as a recirculating stream; 3739.05 kg / h of the liquid phase was sent to a distillation column.

[0064] The distillation column is a valved plate type with 36 trays, and the feed is fed onto the 6th tray. The operating temperature at the top is 40℃, the operating temperature at the bottom is 211.1℃, the operating pressure at the top is 0.6 MPaG, the operating pressure at the bottom is 0.65 MPaG, and the reflux ratio is 3.0. The distillation column separates the C4 hydrogenation product from the circulating solvent N-methylpyrrolidone. The circulating solvent in the bottom is cooled to 30℃ and then returned to the reactor inlet to be mixed again with the butadiene tail gas. The output of non-condensable vapor from the top is 44.92 kg / h, the output of liquid C4 hydrogenation product from the top is 1580 kg / h, and the output of circulating solvent from the bottom is 2114.13 kg / h.

[0065] The catalyst loaded in the reactor is supported on alumina and contains active metallic components such as palladium, lead, and silver.

[0066] The quality composition of each major logistics item is shown in Table 2.

[0067] Table 2

[0068]

[0069]

[0070] The selectivity of 1-butene is defined as follows:

[0071]

[0072] The above 1-butene, alkynes and dienes are calculated in kmol / h.

[0073] As shown in Table 2, the mass fraction of 1-butene in the hydrogenated product is 38.82%, the mass fraction of 1-butene in the feedstock is 19.16%, the selectivity of 1-butene is 56.51%, and the conversion rate of alkynes and dienes is 96.53%.

[0074] Comparative Example 1

[0075] The difference between this comparative example and the apparatus in Example 1 is that no solvent feed line is provided, and no circulating solvent line is included.

[0076] The comparative example of selective hydrogenation of alkynes C4 includes the following steps:

[0077] Liquefied butadiene tail gas 2 from the butadiene extraction unit, temperature 25℃, flow rate 1700 kg / h. Hydrogen gas 1 is mixed with liquefied butadiene tail gas 2. Hydrogen gas temperature 25℃, flow rate 14 kg / h.

[0078] The reactor operating conditions were: 2.0 MPaG, inlet temperature 25.5℃, and outlet temperature 94.6℃. The reactor outlet stream was fed into a vapor-liquid separator. After vapor-liquid two-phase equilibrium separation, the vapor flow rate was 14.10 kg / h, and the liquid flow rate was 1701.48 kg / h. The liquid phase was then sent to a distillation column.

[0079] The distillation column is a valved tray column with 36 trays, and the feed is fed onto the 6th tray. The operating temperature at the top is 49.5℃, the operating temperature at the bottom is 93.7℃, the operating pressure at the top is 0.6 MPaG, the operating pressure at the bottom is 0.65 MPaG, and the reflux ratio is 2.0. The distillation column separates the C4 hydrogenation product from the green oil. The non-condensable vapor output from the top is 0 kg / h, the liquid C4 hydrogenation product output from the top is 1698.48 kg / h, and the green oil output from the bottom is 3 kg / h.

[0080] The catalyst loaded in the reactor is supported on alumina and contains active metallic components such as palladium, lead, and silver.

[0081] The quality composition of each major logistics item is shown in Table 3.

[0082] Table 3

[0083]

[0084]

[0085] The selectivity of 1-butene is defined as follows:

[0086]

[0087] The above 1-butene, alkynes and dienes are calculated in kmol / h.

[0088] As shown in Table 3, the mass fraction of 1-butene in the hydrogenated product is 26.28%, the mass fraction of 1-butene in the feedstock is 24.78%, the selectivity of 1-butene is 20.57%, and the conversion rate of alkynes and dienes is 63.83%.

[0089] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

[0090] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

Claims

1. A method for selective hydrogenation of alkynes to improve butene-1 selectivity, characterized in that, Includes the following steps: (1) Alkyne-containing C4 feedstock, hydrogen and solvent are fed into a hydrogenation reactor and selectively hydrogenated under the action of a catalyst to obtain the hydrogenated material; the flow ratio of the alkyne-containing C4 feedstock to hydrogen is 20 to 50:

1. (2) The material after the hydrogenation reaction enters the gas-liquid separator for gas-liquid separation to obtain hydrogenated liquid C4. The hydrogenated liquid C4 is divided into two parts, one part is used as circulating material 1, and the other part enters the distillation column. (3) The hydrogenated liquid C4 entering the distillation column is distilled in the distillation column. The product C4 is separated at the top of the column, and the recycled material 2 is obtained at the bottom of the column. The recycled material 1 and recycled material 2 are mixed to obtain the total recycled material, which is cooled and returned to the inlet of the hydrogenation reactor.

2. The method for selective hydrogenation of alkynes to improve butene-1 selectivity according to claim 1, wherein, The alkyne C4 selective hydrogenation method is carried out using an alkyne C4 selective hydrogenation device, which includes a hydrogen feed line, an alkyne C4 feed line, a solvent feed line, a hydrogenation reactor, a gas-liquid separator, and a distillation column. The hydrogen feed line and solvent feed line merge, and then merge with the alkyne C4 feed line, and then connect in sequence to the hydrogenation reactor, gas-liquid separator and distillation column; The liquid phase discharge pipeline of the gas-liquid separator is divided into two branches, one of which serves as the circulating material pipeline 1, and the other is connected to the distillation column. The distillation column is equipped with a top discharge pipeline and a bottom discharge pipeline. The bottom discharge pipeline serves as a circulating material pipeline 2. The circulating material pipeline 1 and the circulating material pipeline 2 are connected to the inlet of the hydrogenation reactor after they merge. A cooler is installed on the merging pipeline of circulating material pipeline 1 and circulating material pipeline 2.

3. The method for selective hydrogenation of alkynes to improve butene-1 selectivity according to claim 2, wherein, The merging pipeline of the circulating material pipeline 1 and the circulating material pipeline 2 first merges with the hydrogen feed pipeline, then merges with the C4 alkyne feed pipeline, and then connects to the inlet of the hydrogenation reactor; a gas-liquid mixer is installed on the pipeline connected to the inlet of the hydrogenation reactor.

4. The method for selective hydrogenation of alkynes to improve butene-1 selectivity according to claim 2, wherein, The hydrogenation reactor is a fixed-bed reactor, preferably at least one of a trickle-bed reactor, a bubble-bed reactor, a tubular reactor, and a micro-packed bed.

5. The method for selective hydrogenation of alkynes to improve butene-1 selectivity according to claim 2, wherein, The distillation column is a plate column or a packed column.

6. The method for selective hydrogenation of alkynes to improve butene-1 selectivity according to claim 2, wherein, Both circulating material pipeline 1 and circulating material pipeline 2 are equipped with flow regulating valves.

7. The method for selective hydrogenation of alkynes to improve butene-1 selectivity according to claim 1, wherein, The mass flow rate ratio of the circulating material 1 to the circulating material 2 is 0.1 to 50:1, preferably 0.1 to 40:

1.

8. The method for selective hydrogenation of alkynes to improve butene-1 selectivity according to claim 1, wherein, The mass flow rate ratio of the total circulating material to the C4-containing alkyne feedstock is 0.1 to 80:1, preferably 10 to 60:1; Preferably, the solvent accounts for 0.1% to 90% of the total recycled material, and more preferably 40% to 90%.

9. The method for selective hydrogenation of alkynes to improve butene-1 selectivity according to claim 1, wherein, The total circulating material is cooled to 30-50°C by a cooler before being returned to the inlet of the hydrogenation reactor.

10. The method for selective hydrogenation of alkynes to improve butene-1 selectivity according to claim 1, wherein, The operating conditions for the hydrogenation reaction include: a reaction temperature of 5–100°C, preferably 20–80°C, and a reaction pressure of 0.6–5.0 MPaG.

11. The method for selective hydrogenation of alkynes to improve butene-1 selectivity according to claim 1, wherein, The operating conditions of the distillation column are as follows: 5 to 60 trays, feed position is the 15th to 25th tray, column pressure is 0.1 to 0.6 MPaG, column top temperature is 5 to 60℃, and column bottom temperature is 150 to 350℃.

12. The method for selective hydrogenation of alkynes to improve butene-1 selectivity according to claim 1, wherein, The catalyst includes a support and an active component supported on the support; Preferably, the active component includes a palladium main active component and an auxiliary component. Based on the total weight of the catalyst, the content of the palladium main active component is 0.015-2.0 wt%, the content of the auxiliary component is 0.005-3.0 wt%, and the balance is the support.

13. The method for selective hydrogenation of alkynes to improve butene-1 selectivity according to claim 12, wherein, The carrier is selected from at least one of alumina, titanium dioxide, and magnesium oxide; The auxiliary component is selected from at least one of lead, silver, tin, magnesium and calcium.

14. The method for selective hydrogenation of alkynes to improve butene-1 selectivity according to claim 1, wherein, The circulating solvent is N-methylpyrrolidone.

15. The method for selective hydrogenation of alkynes to improve butene-1 selectivity according to claim 1, wherein, The alkyne-containing C4 feedstock includes C2-C4. 10 At least one of the light hydrocarbon feedstocks; Preferably, based on the total weight of the C4 raw material containing alkynes, the content of alkynes in the C4 raw material is 0.0001 to 40 wt%.

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