Alkyne C4 selective hydrogenation device and method
By using a two-stage hydrogenation reactor system and a circulating solvent, the problem of low reaction selectivity in the recovery and utilization of C4 acetylene tail gas was solved, the yield and conversion rate of 1-butene were improved, the process flow was simplified, and energy consumption and pollutant emissions were reduced.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA PETROLEUM & CHEMICAL CORP
- Filing Date
- 2024-11-19
- Publication Date
- 2026-05-19
AI Technical Summary
In the existing technology, the reaction selectivity in the recovery and utilization of C4 acetylene tail gas is low, which leads to a decrease in the yield of 1-butene. In addition, the process is complicated, the equipment investment is high, the energy consumption is high, and a lot of pollutants are generated.
A two-stage hydrogenation reactor system is adopted, using a circulating solvent as the heat carrier for the reaction. The heat of reaction is removed by controlling the circulating solvent in the first-stage hydrogenation reactor, and the solvent ratio is controlled in the second-stage hydrogenation reactor to improve the reaction selectivity and conversion rate.
It improves the selectivity of 1-butene and the conversion rate of alkynes/dienes, simplifies the process flow, reduces energy consumption, and reduces the generation of pollutants.
Smart Images
Figure CN122057441A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of petrochemicals, specifically relating to a C4 selective hydrogenation apparatus and method for alkynes. 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%. Vinylacetylene poses a self-decomposition and explosion hazard. Generally, this C4-acetylene tail gas is 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 has 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] CN14456029B discloses a method for preparing 1-butene from C4 hydrocarbons, comprising: mixing C4 feedstock and hydrogen for selective hydrogenation to obtain material I; subjecting material I to a first distillation separation to obtain material II containing isobutene, 1-butene, and optionally isobutane, and material III containing 2-butene and optionally n-butane; subjecting material II to a second distillation separation to obtain material IV containing 1-butene and isobutene; subjecting material IV to reactive distillation to obtain material V containing isobutene and material VI containing 2-butene; and subjecting material VI to a second double bond isomerization reaction to obtain material containing 1-butene. This invention has a long process flow, complex equipment structure, and high investment costs.
[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 by providing a C4 selective hydrogenation apparatus and method for alkynes. By employing a two-stage hydrogenation reactor, the concentrations of alkynes and dienes in the hydrogenated products can be effectively maintained, ensuring the smooth and stable operation of downstream user facilities. The first-stage hydrogenation reactor is equipped with a circulation pipeline, using a non-reactive circulating solvent as a means of removing reaction heat, thus avoiding long residence times of reaction products in the reactor. Under these process conditions, the circulating solvent has superior solubility for the target feedstocks alkynes and dienes in the hydrogenation reaction. The circulating solvent, having dissolved the alkynes and dienes, is more likely to react on the catalyst surface. Therefore, using a circulating solvent as the circulating stream allows for control of the removal of reaction heat and the concentrations of alkynes and dienes within the reactor, thereby improving the selectivity of the selective hydrogenation reaction and enhancing the economic efficiency of the equipment. The second-stage hydrogenation reaction system uses a single-pass reactor. By controlling a certain solvent ratio in the second-stage reaction feed, good 1-butene selectivity and alkyne / diene conversion rates can be achieved during the hydrogenation reaction.
[0008] To achieve the above objectives, a first aspect of the present invention provides a selective hydrogenation apparatus for alkyne C4, the apparatus comprising a hydrogen feed line, an alkyne C4 feed line, a solvent feed line, a first-stage hydrogenation reactor, a first-stage gas-liquid separator, a first-stage distillation column, a second-stage hydrogenation reactor, a second-stage gas-liquid separator, and a second-stage distillation column.
[0009] The hydrogen feed line, alkyne C4 feed line, and solvent feed line are connected in sequence to a hydrogenation reactor, a gas-liquid separator, and a distillation column.
[0010] The first-stage distillation column is equipped with a first-stage distillation column top discharge pipeline and a first-stage distillation column bottom discharge pipeline. The first-stage distillation column bottom discharge pipeline serves as a circulating solvent pipeline and is connected to the inlet of the first-stage hydrogenation reactor. A cooler is installed on the circulating solvent pipeline.
[0011] The top discharge pipeline of the first-stage distillation column is sequentially connected to the second-stage hydrogenation reactor, the second-stage gas-liquid separator, and the second-stage distillation column.
[0012] A second aspect of the present invention provides a method for selective hydrogenation of alkynes C4, using the aforementioned selective hydrogenation apparatus for alkynes C4, comprising the following steps:
[0013] (1) Alkyne-containing C4 raw material, hydrogen and solvent enter a first-stage hydrogenation reactor, and under the action of a first-stage catalyst, a first-stage selective hydrogenation reaction is carried out to obtain the material after the first-stage hydrogenation reaction;
[0014] (2) After the hydrogenation reaction, the material undergoes gas-liquid separation and distillation. A C4 material is obtained at the top of the distillation column, and a circulating solvent is obtained at the bottom of the column. The circulating solvent is cooled and returned to the inlet of the hydrogenation reactor.
[0015] (3) The first-stage C4 material enters the second-stage hydrogenation reactor and undergoes a second-stage selective hydrogenation reaction under the action of the second-stage catalyst to obtain the material after the second-stage hydrogenation reaction. The material after the second-stage hydrogenation reaction undergoes a second-stage gas-liquid separation and distillation to obtain the product C4 at the top of the second-stage distillation column.
[0016] The technical solution of the present invention has the following beneficial effects:
[0017] Using the apparatus and method of this invention, a circulating solvent is employed as a circulating heat carrier in the first-stage hydrogenation reaction. This eliminates the residence time of reaction products in the reactor bed due to circulation. Furthermore, compared to butane and isobutane, the introduced circulating solvent has better solubility for the reactants, alkynes and dienes. Therefore, the alkynes and dienes dissolved in the circulating solvent, due to their increased concentration, are more likely to undergo selective hydrogenation on the catalyst surface, forming 1-butene. This solubility further facilitates desorption from the catalyst surface, significantly improving the selectivity of the reaction. In the second-stage hydrogenation reaction, because the exothermic reaction is small, the circulating solvent is not required for heat removal. However, the presence of the solvent effectively improves the selectivity of the reaction. The two-stage hydrogenation system effectively balances reaction selectivity and conversion rate.
[0018] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description
[0019] Exemplary embodiments of the present invention will be described in more detail with reference to the accompanying drawings.
[0020] Figure 1 A process flow diagram of the alkyne C4 selective hydrogenation method of the present invention is shown.
[0021] Explanation of reference numerals in the attached figures
[0022] I: One-stage fixed-bed reactor; II: One-stage vapor-liquid separator; III: One-stage distillation column; IV: Two-stage fixed-bed reactor; V: Two-stage vapor-liquid separator; VI: Two-stage distillation column.
[0023] 1. Hydrogen, 2. Alkyne-containing C4 feedstock, 3. Low-alkyne C4 after primary hydrogenation, 4. Liquid C4 after primary hydrogenation, 5. Primary C4 feedstock, 6. Circulating solvent, 7. Secondary hydrogenated C4 feedstock, 8. Circulating solvent from distillation separation, 9. Secondary hydrogenated C4 product, 10. C4 entering the secondary distillation column, 11. Hydrogenated product, 12. Heavy components, 13. Solvent, 14. Discharge solvent. Detailed Implementation
[0024] 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.
[0025] To achieve the above objectives, a first aspect of the present invention provides a selective hydrogenation apparatus for alkyne C4, the apparatus comprising a hydrogen feed line, an alkyne C4 feed line, a solvent feed line, a first-stage hydrogenation reactor, a first-stage gas-liquid separator, a first-stage distillation column, a second-stage hydrogenation reactor, a second-stage gas-liquid separator, and a second-stage distillation column.
[0026] The hydrogen feed line, alkyne C4 feed line, and solvent feed line are connected in sequence to a hydrogenation reactor, a gas-liquid separator, and a distillation column.
[0027] The first-stage distillation column is equipped with a first-stage distillation column top discharge pipeline and a first-stage distillation column bottom discharge pipeline. The first-stage distillation column bottom discharge pipeline serves as a circulating solvent pipeline and is connected to the inlet of the first-stage hydrogenation reactor. A cooler is installed on the circulating solvent pipeline.
[0028] The top discharge pipeline of the first-stage distillation column is sequentially connected to the second-stage hydrogenation reactor, the second-stage gas-liquid separator, and the second-stage distillation column.
[0029] According to the present invention, preferably, the circulating solvent pipeline first merges with the alkyne C4 feed pipeline, then merges with the hydrogen feed pipeline, and then connects to the inlet of a hydrogenation reactor; a gas-liquid mixer is provided on the pipeline connected to the inlet of the hydrogenation reactor.
[0030] In this invention, the material mixing method can employ various methods such as pipeline free mixing and static mixer mixing to ensure that hydrogen is uniformly dispersed in the liquid phase feed.
[0031] According to the present invention, preferably, the first-stage hydrogenation reactor and the second-stage hydrogenation reactor are each independently a fixed-bed reactor, and more preferably at least one of a trickle-bed reactor, a bubble-bed reactor, a tubular reactor, and a micro-packed bed.
[0032] According to the present invention, preferably, the first-stage distillation column and the second-stage distillation column are each independently a plate column or a packed column, preferably at least one of a floating valve plate column, a fixed valve plate column, a structured packed column and a random packed column.
[0033] According to the present invention, preferably, a flow regulating valve is provided on the circulating solvent pipeline.
[0034] According to the present invention, preferably, the top of the two-stage distillation column is provided with a C4 product discharge pipeline, and the bottom of the column is provided with a heavy component discharge pipeline.
[0035] A second aspect of the present invention provides a method for selective hydrogenation of alkynes C4, using the aforementioned selective hydrogenation apparatus for alkynes C4, comprising the following steps:
[0036] (1) Alkyne-containing C4 raw material, hydrogen and solvent enter a first-stage hydrogenation reactor, and under the action of a first-stage catalyst, a first-stage selective hydrogenation reaction is carried out to obtain the material after the first-stage hydrogenation reaction;
[0037] (2) After the hydrogenation reaction, the material undergoes gas-liquid separation and distillation. A C4 material is obtained at the top of the distillation column, and a circulating solvent is obtained at the bottom of the column. The circulating solvent is cooled and returned to the inlet of the hydrogenation reactor.
[0038] (3) The first-stage C4 material enters the second-stage hydrogenation reactor and undergoes a second-stage selective hydrogenation reaction under the action of the second-stage catalyst to obtain the material after the second-stage hydrogenation reaction. The material after the second-stage hydrogenation reaction undergoes a second-stage gas-liquid separation and distillation to obtain the product C4 at the top of the second-stage distillation column.
[0039] According to the present invention, preferably, the mass flow rate ratio of the alkyne-containing C4 feedstock to the circulating solvent is 0.1 to 50:1, more preferably 20 to 40:1.
[0040] Preferably, based on the total weight of a C4 material, the solvent content is 0.01-20 wt%, more preferably 0.01-5 wt%.
[0041] According to the present invention, preferably, the circulating solvent is cooled to 30-50°C by a cooler and then returned to the inlet of the first-stage hydrogenation reactor.
[0042] According to the present invention, preferably, the operating conditions of the first-stage hydrogenation reaction include: a reaction temperature of 5–100°C, preferably 20–80°C, and a reaction pressure of 0.6–5.0 MPaG; the operating conditions of the second-stage hydrogenation reaction include: a reaction temperature of 5–100°C, preferably 20–80°C, and a reaction pressure of 0.6–5.0 MPaG.
[0043] According to the present invention, preferably, the operating conditions of the first-stage 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 top temperature is 0 to 60°C, and the bottom temperature is 150 to 350°C; the operating conditions of the second-stage 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 top temperature is 0 to 60°C, and the bottom temperature is 150 to 350°C.
[0044] 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.
[0045] According to the present invention, preferably, the circulating solvent is N-methylpyrrolidone.
[0046] In this invention, compared with butene-1 and butadiene, the introduced circulating solvent has better solubility for the reaction raw material vinylacetylene. Therefore, vinylacetylene dissolved in the circulating solvent is more likely to undergo selective hydrogenation on the catalyst surface due to concentration enrichment. After generating butadiene, it is more likely to desorb from the catalyst surface due to solubility, thus greatly improving the selectivity of the reaction.
[0047] According to the present invention, preferably, the alkyne-containing C4 raw material comprises C2 to C4. 10 At least one of the light hydrocarbon feedstocks.
[0048] 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%.
[0049] 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.
[0050] Example 1
[0051] This embodiment provides a C4 selective hydrogenation device for alkynes, such as... Figure 1 As shown, the device includes a hydrogen feed line, an alkyne C4 feed line, a solvent feed line, a first-stage fixed-bed reactor I, a first-stage gas-liquid separator II, a first-stage distillation column III, a second-stage fixed-bed reactor IV, a second-stage gas-liquid separator V, and a second-stage distillation column VI; both the first-stage and second-stage distillation columns are fixed valve plate type columns.
[0052] After the hydrogen feed line, alkyne C4 feed line, and solvent feed line converge, they are sequentially connected to a fixed-bed reactor I, a gas-liquid separator II, and a distillation column III.
[0053] The first-stage distillation column III is equipped with a top discharge pipeline and a bottom discharge pipeline. The bottom discharge pipeline serves as a circulating solvent pipeline. The circulating solvent pipeline first merges with the alkyne C4 feed pipeline, then merges with the hydrogen feed pipeline, and then connects to the inlet of the first-stage hydrogenation reactor. The circulating solvent pipeline is equipped with a flow regulating valve and a cooler, and a gas-liquid mixer is installed on the pipeline connected to the inlet of the first-stage hydrogenation reactor.
[0054] The top discharge pipeline of the first-stage distillation column is sequentially connected to the second-stage fixed-bed reactor IV, the second-stage gas-liquid separator V, and the second-stage distillation column VI. The top of the second-stage distillation column VI is equipped with a C4 product discharge pipeline, and the bottom of the column is equipped with a heavy component discharge pipeline.
[0055] Example 2
[0056] This embodiment provides a method for selective hydrogenation of alkynes at C4, using the apparatus of Example 1, and includes the following steps:
[0057] Liquefied butadiene tail gas 2 from the butadiene extraction unit, temperature 25℃, flow rate 1700 kg / h. Circulating stream 6, temperature 40℃, flow rate 46300 kg / h. Liquefied butadiene tail gas 2 is thoroughly mixed with the circulating solvent N-methylpyrrolidone, and then mixed with hydrogen gas 1. Hydrogen temperature 25℃, flow rate 50 kg / h.
[0058] The operating conditions of the first-stage hydrogenation reactor are: 2.0 MPaG, inlet temperature 38℃, and outlet temperature 69.8℃. The outlet stream from the first-stage hydrogenation reactor is sent to a first-stage vapor-liquid separator. After vapor-liquid two-phase equilibrium separation, the vapor flow rate is 0 kg / h, and the liquid flow rate is 49750 kg / h, all of which is sent to the distillation column.
[0059] The first-stage distillation column is a valved plate column with 36 trays, and the feed is fed onto the 20th tray. The operating temperature at the top is 20°C, the operating temperature at the bottom is 294.4°C, 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°C and returned to the reactor inlet to be mixed again with the butadiene tail gas. The column produces 54.69 kg / h of non-condensable vapor at the top, 1695.31 kg / h of liquid C4 hydrogenation product (of which the solvent content is 0.23 wt% based on the total weight of the liquid C4 hydrogenation product), and 48,000 kg / h of circulating solvent in the bottom.
[0060] The operating conditions for the two-stage hydrogenation reactor are: 2.0 MPaG, inlet temperature 40℃, and outlet temperature 54.4℃. The outlet stream from the two-stage hydrogenation reactor is sent to the two-stage vapor-liquid separator. After vapor-liquid two-phase equilibrium separation, the vapor flow rate is 0 kg / h, and the liquid flow rate is 1696.81 kg / h, which is then sent to the two-stage distillation column.
[0061] The two-stage distillation column is a valved tray column with 30 trays, and the feed is fed onto the 15th tray. The operating temperature at the top is 40℃, the operating temperature at the bottom is 132.7℃, 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 liquid phase at the top of the second distillation column is 1620 kg / h of C4 product, the non-condensable vapor output at the top is 66.81 kg / h, and the bottom contains heavy components at 10 kg / h.
[0062] The catalysts loaded in the first and second stage reactors are supported on alumina and contain active metallic components such as palladium, lead and silver.
[0063] The quality composition of each major logistics item is shown in Table 1.
[0064] Table 1
[0065]
[0066]
[0067] The selectivity of 1-butene is defined as follows:
[0068]
[0069] The above 1-butene, alkynes and dienes are calculated in kmol / h.
[0070] The conversion rates of alkynes and dienes are defined as follows:
[0071]
[0072] The above alkynes and dienes are calculated in kmol / h.
[0073] As shown in Table 1, the mass fraction of 1-butene in the hydrogenated product is 39.23%, the mass fraction of 1-butene in the feedstock is 19.16%, the selectivity of 1-butene is 55.97%, and the conversion rate of alkynes and dienes is 100%.
[0074] Example 3
[0075] Liquefied butadiene tail gas 2 from the butadiene extraction unit, temperature 25℃, flow rate 1700 kg / h. Circulating stream 6, temperature 25℃, flow rate 35000 kg / h. Liquefied butadiene tail gas 2 is thoroughly mixed with the circulating solvent N-methylpyrrolidone, and then mixed with hydrogen gas 1. Hydrogen temperature 25℃, flow rate 50 kg / h.
[0076] The operating conditions of the first-stage hydrogenation reactor are: 2.0 MPaG, inlet temperature 25.1℃, and outlet temperature 65.6℃. The outlet stream from the first-stage hydrogenation reactor is sent to a first-stage vapor-liquid separator. After vapor-liquid two-phase equilibrium separation, the vapor flow rate is 0 kg / h, and the liquid flow rate is 38450 kg / h, all of which is sent to the distillation column.
[0077] The first-stage distillation column is a packed column using 250Y type packing with a height of 18 meters and a central feed position. The operating temperature at the top is 0℃, the operating temperature at the bottom is 153.7℃, the operating pressure at the top is 0.5 MPaG, the operating pressure at the bottom is 0.55 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 25℃ and returned to the reactor inlet to be mixed again with the butadiene tail gas. The top output of non-condensable vapor is 22.78 kg / h, the top output of liquid C4 hydrogenation product is 1600 kg / h (of which, based on the total weight of the liquid C4 hydrogenation product, the solvent content is 0.003 wt%), and the bottom output of circulating solvent is 36827.22 kg / h.
[0078] The operating conditions for the two-stage hydrogenation reactor are: 2.0 MPaG, inlet temperature 25℃, and outlet temperature 34.9℃. The outlet stream from the two-stage hydrogenation reactor is sent to the two-stage vapor-liquid separator. After vapor-liquid two-phase equilibrium separation, the vapor flow rate is 0 kg / h, and the liquid flow rate is 1601 kg / h, which is then sent to the two-stage distillation column.
[0079] The second-stage distillation column is a packed column using 250Y type packing with a packing height of 15 meters and a central feed position. The operating temperature at the top is 36.3℃, the operating temperature at the bottom is 151℃, the operating pressure at the top is 0.5 MPaG, the operating pressure at the bottom is 0.55 MPaG, and the reflux ratio is 2.0. The liquid phase at the top of the second distillation column is 1550 kg / h of C4 product, the non-condensable vapor at the top is 41 kg / h, and the bottom contains heavy components at 10 kg / h.
[0080] The catalysts loaded in the first and second stage reactors are supported on alumina and contain active metallic components such as palladium, lead and silver.
[0081] The quality composition of each major logistics item is shown in Table 2.
[0082] Table 2
[0083]
[0084]
[0085]
[0086] The selectivity of 1-butene is defined as follows:
[0087]
[0088] The above 1-butene, alkynes and dienes are calculated in kmol / h.
[0089] The conversion rates of alkynes and dienes are defined as follows:
[0090]
[0091] The above alkynes and dienes are calculated in kmol / h.
[0092] As shown in Table 2, the mass fraction of 1-butene in the hydrogenated product is 39.93%, the mass fraction of 1-butene in the feedstock is 19.16%, the selectivity of 1-butene is 52.83%, and the conversion rate of alkynes and dienes is 100%.
[0093] Comparative Example 1
[0094] 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.
[0095] The comparative example of selective hydrogenation of alkynes C4 includes the following steps:
[0096] 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 5 kg / h.
[0097] The reactor operating conditions were: 2.0 MPaG, inlet temperature 28.6℃, and outlet temperature 86.7℃. The reactor outlet stream was sent to a vapor-liquid separator. After vapor-liquid two-phase equilibrium separation, the vapor flow rate was 0 kg / h, and the liquid flow rate was 1705.00 kg / h. The liquid phase was then sent to a distillation column.
[0098] The distillation column is a valved tray column with 36 trays, and the feed is fed onto the 12th tray. The operating temperature at the top is 40℃, the operating temperature at the bottom is 58.5℃, the operating pressure at the top is 0.5 MPaG, the operating pressure at the bottom is 0.55 MPaG, and the reflux ratio is 2.0. The distillation column separates the C4 hydrogenated product from the green oil. The top product yields 5.36 kg / h of non-condensable vapor, 1650 kg / h of liquid C4 hydrogenated product, and 49.62 kg / h of C4-containing green oil.
[0099] The reactor is packed with a catalyst supported on alumina, which contains active metallic components such as palladium, lead, and silver. The mass composition of the main streams is shown in Table 3.
[0100] Table 3
[0101]
[0102]
[0103] The selectivity of 1-butene is defined as follows:
[0104]
[0105] The above 1-butene, alkynes and dienes are calculated in kmol / h.
[0106] The conversion rates of alkynes and dienes are defined as follows:
[0107]
[0108] The above alkynes and dienes are calculated in kmol / h.
[0109] As shown in Table 3, the mass fraction of 1-butene in the hydrogenated product is 15.12%, the mass fraction of 1-butene in the feedstock is 12.20%, the selectivity of 1-butene is 34.16%, and the conversion rate of alkynes and dienes is 100%.
[0110] 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.
[0111] 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 C4 selective hydrogenation apparatus for alkynes, characterized in that, The device includes a hydrogen feed line, an alkyne C4 feed line, a solvent feed line, a first-stage hydrogenation reactor, a first-stage gas-liquid separator, a first-stage distillation column, a second-stage hydrogenation reactor, a second-stage gas-liquid separator, and a second-stage distillation column. The hydrogen feed line, alkyne C4 feed line, and solvent feed line are connected in sequence to a hydrogenation reactor, a gas-liquid separator, and a distillation column. The first-stage distillation column is equipped with a first-stage distillation column top discharge pipeline and a first-stage distillation column bottom discharge pipeline. The first-stage distillation column bottom discharge pipeline serves as a circulating solvent pipeline and is connected to the inlet of the first-stage hydrogenation reactor. A cooler is installed on the circulating solvent pipeline. The top discharge pipeline of the first-stage distillation column is sequentially connected to the second-stage hydrogenation reactor, the second-stage gas-liquid separator, and the second-stage distillation column.
2. The alkyne C4 selective hydrogenation apparatus according to claim 1, wherein, The circulating solvent pipeline first merges with the alkyne C4 feed pipeline, then merges with the hydrogen feed pipeline, and then connects to the inlet of a hydrogenation reactor section; a gas-liquid mixer is installed on the pipeline connected to the inlet of the hydrogenation reactor section.
3. The alkyne C4 selective hydrogenation apparatus according to claim 1, wherein, The first-stage hydrogenation reactor and the second-stage hydrogenation reactor are each independently 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.
4. The alkyne C4 selective hydrogenation apparatus according to claim 1, wherein, The first-stage distillation column and the second-stage distillation column are each independently either plate columns or packed columns.
5. The alkyne C4 selective hydrogenation apparatus according to claim 1, wherein, A flow regulating valve is installed on the circulating solvent pipeline.
6. The alkyne C4 selective hydrogenation apparatus according to claim 1, wherein, The two-stage distillation column is equipped with a C4 product discharge pipeline at the top and a heavy component discharge pipeline at the bottom.
7. A method for selective hydrogenation of alkynes at C4, characterized in that, The process, performed using the alkyne C4 selective hydrogenation apparatus according to any one of claims 1-6, includes the following steps: (1) Alkyne-containing C4 raw material, hydrogen and solvent enter a first-stage hydrogenation reactor, and under the action of a first-stage catalyst, a first-stage selective hydrogenation reaction is carried out to obtain the material after the first-stage hydrogenation reaction; (2) After the hydrogenation reaction, the material undergoes gas-liquid separation and distillation. A C4 material is obtained at the top of the distillation column, and a circulating solvent is obtained at the bottom of the column. The circulating solvent is cooled and returned to the inlet of the hydrogenation reactor. (3) The first-stage C4 material enters the second-stage hydrogenation reactor and undergoes a second-stage selective hydrogenation reaction under the action of the second-stage catalyst to obtain the material after the second-stage hydrogenation reaction. The material after the second-stage hydrogenation reaction undergoes a second-stage gas-liquid separation and distillation to obtain the product C4 at the top of the second-stage distillation column.
8. The method for selective hydrogenation of alkynes to C4 hydrocarbons according to claim 7, wherein, The mass flow rate ratio of the alkyne-containing C4 feedstock to the circulating solvent is 0.1 to 50:1, preferably 20 to 40:1; Based on the total weight of a C4 material, the solvent content is 0.01-20 wt%, preferably 0.01-5 wt%.
9. The method for selective hydrogenation of alkynes to C4 hydrocarbons according to claim 7, wherein, The circulating solvent is cooled to 30-50°C by a cooler before being returned to the inlet of the first-stage hydrogenation reactor.
10. The method for selective hydrogenation of alkynes to C4 according to claim 7, 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; The operating conditions for the two-stage 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 C4 according to claim 7, 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 0 to 60°C, and column bottom temperature is 150 to 350°C. The operating conditions of the two-stage 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 0 to 60℃, and column bottom temperature is 150 to 350℃.
12. The method for selective hydrogenation of alkynes to C4 hydrocarbons according to claim 7, wherein, The first-stage catalyst and the second-stage catalyst may be the same or different, and each independently 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 C4 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 C4 according to claim 7, wherein, The circulating solvent is N-methylpyrrolidone.
15. The method for selective hydrogenation of alkynes to C4 according to claim 7, 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%.