Method for producing butene-1 from C4 light hydrocarbon

Abstract

The invention relates to a method for producing butylene-1 from C4 light hydrocarbon, and belongs to the field of C4 light hydrocarbon processing and application. The method solves the technical problems of high energy consumption and poor economical efficiency during separation and preparation of butene-1 after catalytic cracking of mixed C4 with high alkane content and low olefin content in the prior art. The method for producing butene-1 comprises the following steps: feeding etherified C4 into a precise rectifying tower, carrying out rectification separation on light and heavy C4, carrying out selective hydrogenation to remove butadiene from a fraction rich in butene-1 and iso-butane, feeding the fraction into an extractive distillation tower, carrying out alkane-olefin separation, carrying out water washing on raffinate to remove an entrained extractant, and carrying out distillation to obtain the butene-1, wherein the fraction is extracted from a side line of the tower and is rich in butene-1 and iso-butane; and refining in a butene-1 refining tower, and extracting a butene-1 product from the tower top. According to the method, the process can be shortened, the energy consumption can be reduced, impurities in the raw materials can be removed, the method has the characteristics of high operability and high butylene-1 yield, and a high-purity isobutane product can be obtained.

Description

Technical Field

[0001] The invention relates to a method for producing butene-1 from C4 light hydrocarbons, and belongs to the field of C4 light hydrocarbon processing applications. The method is mainly suitable for producing butene-1 from mixed C4 fractions produced by processes such as petrochemical refining catalytic cracking, and can also be used to produce butene-1 from post-ether C4 fractions in processes such as steam cracking and coal chemical industry. Background Art

[0002] Butene-1 (English name 1-butene) is a colorless transparent gas with a boiling point of -6°C. It is flammable and low in toxicity. It is mainly used as a comonomer for HDPE and LLDPE. It can also be used to produce products such as polybutene-1, 1-octene and dodecene.

[0003] At present, the C4 resources for producing butene-1 are mainly C4 from petrochemical ethylene cracking and a small amount of C4 produced as a by-product of coal chemical MTO units. The production routes of butene-1 are mainly divided into two categories: mixed C4 separation method and ethylene dimerization method. The ethylene dimerization method is to produce high-purity butene-1 by dimerizing ethylene under the action of Zegler-Netta catalyst. Since the raw material of this method is ethylene, which is more valuable than butene-1, the production cost is relatively high. At present, the production of butene-1 is mainly based on the mixed C4 separation method. The usual technical route is: first, butadiene is removed by butadiene extraction or hydrogenation, then isobutylene is removed by the MTBE method, and finally a high-purity butene-1 product is separated by precise fractionation, and a hydrocarbon mixture rich in 2-butene (mainly 2-butene and n-butane) is obtained.

[0004] The comprehensive utilization of C4 components in refineries is one of the hot spots for comprehensive utilization of C4 resources. With a wide source base, most of the C4 resources produced as byproducts of catalytic cracking are burned as fuel, resulting in a waste of C4 resources. For enterprises that are mainly engaged in refining and chemical industry, if C4 can be reasonably utilized in chemical industry, it can effectively improve the utilization level of resources and improve the overall economic benefits of the enterprise.

[0005] Patent CN114456029A provides a method for preparing butene-1 from C4 hydrocarbons, including mixing a C4 raw material and hydrogen for a selective hydrogenation reaction, subjecting the product to a first distillation separation to separate material II containing isobutylene, butene-1 and isobutane from material III containing 2-butene and normal butane, and then subjecting material II containing isobutylene, butene-1 and isobutane to a second distillation to separate isobutane, subjecting material IV containing butene-1 and isobutylene to reactive distillation to obtain material V containing isobutylene and material VI containing 2-butene, and subjecting the material containing 2-butene to a second double bond isomerization reaction to obtain material containing butene-1. The process flow is long and the energy consumption is high.

[0006] CN102992933 discloses a method for separating mixed C4, wherein the mixed C4 containing n-butane, isobutane, butene-1 and 2-butene after removing components such as C3, butadiene, alkynes, isobutene and C5 is subjected to two extractive distillations to separate isobutane, n-butane and butene respectively, and further separated by ordinary distillation to obtain isobutane, butene-1, 2-butene and crude n-butane products; the process flow is relatively complicated and the energy consumption of the extractive distillation is relatively high.

[0007] CN101544532A provides a method for producing butene-1 using C4 byproduct of ethylene cracking and C4 byproduct of catalytic cracking as raw materials, belonging to the field of petrochemical technology. The method is to separate the mixed C4 byproduct of catalytic cracking into light and heavy C4 by gas fractionation device, and then separate the light C4 to obtain concentrated isobutane component and isobutylene and butene-1 component; the isobutylene and butene-1 components are deeply desulfurized and purified and then concentrated, and butadiene is removed by selective hydrogenation, and then mixed with the product of C4 raffinate oil byproduct of ethylene cracking and enter the chemical MTBE device for etherification and distillation to obtain polymerization-grade butene-1 product. The process route of the invention is long and the energy consumption is high.

[0008] CN101050159A provides a method for separating butane from butene and a special device thereof, wherein the method adopts a raw material pretreatment distillation tower, removes isobutane at the top, extracts mixed normal isobutene and butadiene from the side line to remove light and heavy components, extracts butene-2 ​​and normal butane from the bottom to remove heavy components; separates normal butane from the top of the heavy component extraction distillation tower, and obtains butene-2 ​​at the bottom; separates isobutane from the top of the light and heavy component extraction distillation tower, mixes the bottom material with the material extracted from the bottom of the heavy component extraction distillation tower and enters a degassing tower, and extracts mixed butene from the top of the degassing tower. The invention can effectively improve the yield and purity of each component separated from the carbon four component raw material, and reduce the amount of extractant used, but the disadvantage is that only mixed butene can be obtained.

[0009] CN1170793C discloses a method for separating butane and butene using a methyl ethyl ketone series mixed solvent. The technology uses methyl ethyl ketone and a polar solvent, such as nitrogen-formyl morpholine, morpholine or a mixture of the two, cyclopentane, etc. as solvents, extractive distillation to separate butane and butene. The solvent has good solubility in carbon four and low viscosity. There is basically no double liquid phase and no foaming phenomenon in the tower. The extractive distillation tower and the analytical tower are pressurized, the tower top temperature is about 45°C, the tower bottom temperature is lower than 170°C, the solvent ratio is 9-15, the butene product purity is greater than 97%, and the highest can reach more than 99%, and the butene yield is 95%-97%. However, only alkane and alkene separation is performed.

[0010] CN101544532B discloses a method for producing butene-1 using C4 as a by-product of catalytic cracking and C4 as a by-product of ethylene cracking as raw materials. The method comprises the following steps: firstly, the mixed C4 is introduced into a gas fractionation tower, and a light component material containing isobutane, isobutylene and butene-1 is obtained at the top of the tower; then, the material is introduced into a fractionation tower, and most of the isobutane is separated from the top of the tower, and a heavy component material containing isobutylene and butene-1 is obtained at the bottom of the tower; then, the heavy component material is subjected to deep desulfurization and selective hydrogenation to remove butadiene; then, isobutylene is removed by MTBE etherification reaction; and finally, the C4 after etherification is subjected to rectification and separation to obtain a butene-1 product.

[0011] CN1355158A discloses a method for producing high-purity butene-1 by utilizing sulfur-containing C4 fraction. The method uses C4 after isobutylene is removed from the ether as raw material. First, the raw material is introduced into a first distillation tower, and isobutane, C3 fraction and some light components containing sulfur compounds are separated at the top of the tower. The heavy components containing butene-1, 2-butene and normal butane in the bottom of the tower enter a second distillation tower. In the second distillation tower, butadiene is selectively hydrogenated, and sulfide is extracted from the bottom of the tower. Butene-1 product is obtained from the top of the tower or the side line. If necessary, butene-1 product can also be produced by catalytic distillation of 2-butene isomerization to butene-1.

[0012] CN104876785A discloses a process and device for producing MTBE / butene-1 from residual C4. The method uses residual C4 as raw material and adopts the MTBE method to remove the isobutylene component in the C4 raw material. The MTBE reaction equipment includes an etherification reactor and a catalytic distillation tower. The C4 material from which isobutylene is removed is separated into the butene-1 product by bulkhead distillation.

[0013] CN1990438B discloses a method for preparing butene-1 from an industrial mixture of C4 hydrocarbons. The method uses an industrial mixture I of C4 hydrocarbons containing at least butene-1, isobutylene, n-butane and 2-butene as a raw material. First, part of the isobutylene in the C4 raw material I is reacted by reacting isobutylene with water, alcohol or formaldehyde, or by oligomerization of isobutylene to obtain a material II having a boiling point higher than 30°C under standard pressure; then, unconverted C4 hydrocarbons in the material II are removed by a thermal separation method to obtain a material III; then, the material III is treated by a distillation separation method to obtain a material IV containing at least butene-1 and isobutylene and a material V containing at least 2-butene and n-butane and substantially free of isobutylene; then, an etherification method is used to react the isobutylene in the material IV with the alcohol VI to obtain tert-butyl ether VII, while removing the unconverted C4 hydrocarbons in the butene-1-containing logistics to obtain a material VIII; finally, butene-1 is separated from the material VIII by distillation.

[0014] CN101514135B discloses a method for preparing butene-1 by catalytic isomerization of a C4 mixture, wherein the C4 material is heated to 300-350°C and then fed into a reactor, 2-butene isomerized into butene-1 under the action of a solid acid catalyst, the reaction product is passed into a concentration tower, a mixture rich in butene-1 is obtained at the top of the tower, and a part of the heavy components in the bottom of the tower is circulated back to the reactor. The method has high requirements for the feed of C4 raw materials and can only process C4 raw materials rich in 2-butene.

[0015] In the above methods, the alkanes and olefins in the mixed C4 are separated by extractive distillation, or the isobutylene is removed by the MTBE method, butene-1 is separated by distillation, or butene-1 is directly produced using etherified C4 as raw material. However, all of them have the problems of long process and high energy consumption; and most of the processes do not remove butadiene in the raw materials.

[0016] Since catalytic C4 contains a small amount of butadiene, which has a boiling point difference of about 1.8°C from butene-1, it is difficult to remove it by conventional distillation. When butene-1 is used, clear indicators are put forward for the butadiene content. Therefore, all butene-1 units must add a butadiene removal process before producing butene-1 to control its content within its quality standards. The best way to remove butadiene is selective hydrogenation. Although the existing catalytic C4 selective hydrogenation catalyst has good hydrogenation activity when used in industry, it also has a certain butene-1 isomerization phenomenon, resulting in a significantly low yield of catalytic C4 butene-1 with a low content. Therefore, it is necessary to develop a new catalyst that is suitable for catalytic C4 and has the characteristics of selective hydrogenation to remove butadiene while maintaining a high butene-1 yield.

[0017] Usually, light hydrocarbon hydrogenation uses metals of Group VIII such as Pt, Pd, Ni, Ru, Rh, and Co. Studies have found that precious metals have high intrinsic activity for hydrogenation reactions. Among them, the precious metal Pd catalyst is more suitable for selective hydrogenation reactions due to its high activity, large processing capacity, good catalyst stability, long service life, and mild operating conditions.

[0018] CN109485536A discloses a method for selective hydrogenation of alkynes and / or dienes in a C4 fraction, wherein the active metal component of the supported hydrogenation catalyst is 0.01-0.5wt% palladium, the auxiliary agent is 0-15wt% silver, and the carrier is alumina. The bulk density can be 0.5-1.5g / cm 3 , the specific surface area can be 5~350m 2 / g. Butadiene can be hydrogenated to less than 10 ppm by one or more hydrogenation reactors, but the butene-1 selectivity is not mentioned.

[0019] CN1238239A discloses a method for preparing a catalyst for selective hydrogenation of dienes in carbon four fractions. The main technical feature is that palladium or palladium and gold are loaded on a δ, θ, α mixed phase alumina carrier, the content of the active component palladium on the carrier is 0.05-0.5% (m / m), and the content of gold on the carrier is 0.005-0.05%. The prepared catalyst has the ability to resist sulfur poisoning, high activity and good selectivity. -1 Under the conditions of temperature 50°C, pressure 1.5MPa and hydrogen-to-dienes ratio 2.0mol / mol, the hydrogenation conversion rate was 99.11% and the olefin yield was 100.82%.

[0020] In summary, the catalysts disclosed in existing patents and technologies are mainly palladium-based catalysts. Other types of catalysts have high olefin hydrogenation losses and low butene yields during hydrogenation reactions, and their low-temperature hydrogenation activity and selectivity are much lower than those of palladium-based metal catalysts. Therefore, it is necessary to develop a new type of precious metal palladium catalyst and method that has both high butadiene hydrogenation activity and high butene-1 yield. Summary of the invention

[0021] One of the purposes of the present invention is to solve the technical problems of high energy consumption and poor economy in the separation and preparation of butene-1 from mixed C4 with high alkane and low olefin content components in the prior art through catalytic cracking, and to provide a method for producing butene-1 from C4 light hydrocarbons. The method comprises precise fractionation, extractive distillation and selective hydrogenation reaction processes, which can shorten the process, reduce energy consumption and remove raw material impurities at the same time. The method has the characteristics of strong operability and high butene-1 yield, and can also obtain a high-purity isobutane product.

[0022] The second purpose of the present invention is to solve the technical problem that although the selective hydrogenation catalyst for catalyzing carbon four has good hydrogenation activity, there is also a certain butene-1 isomerization phenomenon, resulting in a low yield of butene-1, and to provide a selective catalyst for catalyzing carbon four.

[0023] The technical solution adopted by the present invention to solve the above technical problems is as follows.

[0024] The present invention provides a method for producing butene-1 from C4 light hydrocarbons, comprising the following steps:

[0025] Step 1: transport the post-ether C4 to a precision distillation tower, obtain a C4 light component isobutane stream at the top of the tower, obtain a heavy C4 stream at the bottom of the tower, and extract a C4 component stream rich in butene-1 from the side line of the tower;

[0026] Step 2: Combine the C4 stream rich in butene-1 and the hydrogen stream and transport them to a hydrogenation reactor to remove butadiene carried in the C4 stream rich in butene-1 to obtain a hydrogenated material;

[0027] Step 3, transporting the hydrogenated material to an extractive distillation tower, extracting and distilling with an extractant, producing an isobutane fraction at the top of the tower, combining it with the C4 light component isobutane stream produced at the top of the precision distillation tower and delivering it, and producing a rich extractant stream containing a mixed solvent and butene at the bottom of the tower;

[0028] Step 4: conveying the rich extractant stream to the desolventizing tower, extracting the n-butene stream at the top of the tower, extracting the lean extractant stream at the bottom of the tower, and returning the lean extractant stream to the extractive distillation tower for reuse after heat recovery;

[0029] Step 5: transport the n-butene stream to a water washing tower to remove the entrained extractant by water washing, extract the n-butene stream after water washing from the top of the tower, and extract the water stream containing the extractant from the bottom of the tower and transport it to a sewage treatment plant or an extractant recovery device;

[0030] Step 6. The normal butene stream after water washing is transported to the butene-1 refining tower, the butene-1 stream is collected from the top of the tower and stored, and the C4 stream containing butene-1 is collected from the bottom of the tower and combined with the new post-ether C4 and transported to the precision distillation tower.

[0031] Preferably, in step 1, the process for obtaining the etherified C4 is as follows: the mixed C4 is transported to an MTBE device, isobutylene is removed through an etherification reaction, and the etherified C4 is obtained.

[0032] Preferably, in step 1, the number of theoretical plates of the precision distillation tower is 102, and a C4 stream rich in butene-1 is obtained by side-drawing at 15 to 40 theoretical plates in the tower.

[0033] Preferably, in step 1, the working conditions of the precision distillation tower are: pressure 0.4-2.0 MPa, temperature 40-110° C., and reflux ratio 4-20.

[0034] Preferably, in step 2, the working conditions of the hydrogenation reactor are: reaction pressure 1.5 MPa, temperature 40-60°C, hydrogen-to-diene ratio 1.1-2.0 mol / mol, space velocity 5h -1 .

[0035] Preferably, in step 2, the selective hydrogenation catalyst used in the hydrogenation reactor comprises a carrier, a main hydrogenation active component, a first auxiliary active component and a second auxiliary active component; the carrier is one or both of aluminum oxide and silicon oxide, the main hydrogenation active component is a mixture of one or more of Group VIII metal elements, the first auxiliary active component is a mixture of one or more of Group IA metal elements, and the second auxiliary active component is a mixture of one or more of Group IB metal elements.

[0036] More preferably, the carrier is composed of 80-95 wt % of α-phase alumina and 5-20 wt % of θ-phase alumina.

[0037] More preferably, the specific surface area of ​​the carrier is 20 to 300 m 2 / g, the specific pore volume is 0.2-0.8 ml / g, the pore radius is 5.0-15 nm; the specific surface area is particularly preferred to be 50-150 m 2 / g.

[0038] More preferably, the main active component of hydrogenation is Ni, Pd or a mixture of the two, and particularly preferably Pd.

[0039] More preferably, the first co-active component is K, Na or a mixture of the two.

[0040] More preferably, the second co-active component is Ag.

[0041] More preferably, the content of the hydrogenation main active component on the carrier is 0.05-0.5% (m / m), and particularly preferably, 0.1-0.3% (m / m).

[0042] More preferably, the content of the first co-active component on the carrier is 0.05-3.0% (m / m), and particularly preferably, 0.1-2.0% (m / m).

[0043] More preferably, the content of the second co-active component on the carrier is 0.05-4.0% (m / m), and particularly preferably, 0.1-3.0% (m / m).

[0044] More preferably, the preparation method of the selective hydrogenation catalyst is:

[0045] First, the raw material of the carrier is mixed evenly with the aqueous solution of the soluble salt of the first auxiliary active component, and after kneading, molding and drying, it is roasted at 400-1200°C for 2-16 hours to obtain the carrier loaded with the first auxiliary active component; then the carrier loaded with the first auxiliary active component is first immersed in the aqueous solution of the soluble salt of the hydrogenation main active component, and after the solution becomes transparent, it is immersed in the aqueous solution of the soluble salt of the second auxiliary active component, and after the solution becomes transparent, it is filtered, or the carrier loaded with the first auxiliary active component is immersed in the aqueous solution containing the soluble salt of the hydrogenation main active component and the soluble salt of the second auxiliary active component, and after the solution becomes transparent, it is filtered; finally, it is dried and roasted at 300-600°C for 3-6 hours to obtain the selective hydrogenation catalyst.

[0046] It is particularly preferred that the raw material of the carrier is firstly mixed with the aqueous solution of the soluble salt of the first co-active component, and one or both of a binder and a pore-enlarging agent are added and mixed evenly, the amount of the pore-enlarging agent added is 1 to 4 wt% of the raw material of the carrier, and the amount of the binder added is 1 to 5 wt% of the raw material of the carrier; most preferably, the binder is sesbania powder and the pore-enlarging agent is citric acid;

[0047] It is particularly preferred that a competitive adsorbent is further added to the aqueous solution of the soluble salt of the main hydrogenation active component or the aqueous solution containing the soluble salt of the main hydrogenation active component and the soluble salt of the second auxiliary active component, the competitive adsorbent is an organic acid or an inorganic acid, the organic acid is formic acid, acetic acid or oxalic acid, the inorganic acid is nitric acid or hydrochloric acid, and the amount of the competitive adsorbent is 1.0 to 10.0 wt% of the soluble salt of the main hydrogenation active component;

[0048] It is particularly preferred that the drying temperature is 100-300°C.

[0049] It is particularly preferred that the immersion temperature is from room temperature to 100°C.

[0050] It is particularly preferred that the soluble salts are independently nitrates or chlorides of the corresponding elements.

[0051] Preferably, in step 3, the number of theoretical plates of the extractive distillation tower is 95, and the extractant stream includes acetonitrile, DMF or N-methylpyrrolidone, which is added from 5 to 10 theoretical plates.

[0052] Preferably, in step three, the working conditions of the extractive distillation tower are: pressure 0.4-0.7 MPa, reflux ratio 1-5, and solvent ratio 2-10.

[0053] Preferably, in step 4, the number of theoretical plates of the desolventizing tower is 22.

[0054] Preferably, in step 4, the working conditions of the desolventizing tower are: pressure 0.4-0.7 MPa, and reflux ratio 1-5.

[0055] Preferably, in step five, the n-butene stream enters from the bottom of the water scrubber, and the water stream enters from the top of the water scrubber, with an oil-to-water ratio of 1 to 20:1.

[0056] Preferably, in step 5, the heat of the lean extractant stream is used for the butene-1 column and the precision distillation column. 。

[0057] Preferably, in step six, the working conditions of the butene-1 refining tower are: pressure 0.4-0.7 MPa, reflux ratio 1-5.

[0058] The principle of the present invention is as follows: for catalytic cracking (FCC) C4 raw materials, due to the high content of isobutane components in the raw materials, after isobutene is removed by reaction in an MTBE device, if the raw materials are directly fed into an extractive distillation tower for separation of alkanes and olefins, a large amount of extractant will need to be circulated in the extraction system due to the high ratio of the extractant to the hydrocarbon material, and the raffinate is mainly butene-1 and butene-2 ​​components, and butene-1 still needs to be separated by precise fractionation, resulting in a large separation energy consumption; the method for producing butene-1 from C4 light hydrocarbons of the present invention, firstly The carbon four after etherification is sent to the precision distillation tower for distillation and separation of light and heavy carbon four. The isobutane with a higher content is extracted from the top of the tower, and normal butane and butene-2 ​​are extracted from the bottom of the tower as heavy carbon four, and the device is used for dealkylation. The side line of the tower extracts the fraction rich in butene-1 and isobutane, and after selective hydrogenation to remove butadiene, it enters the extractive distillation tower for alkane-olefin separation. Since most of the isobutane and normal butane have been separated, the material volume of this stream is small, the circulation volume of the extraction solvent is small, it is more economical than the traditional process route, and the energy consumption of the extraction system is lower. The raffinate is washed with water to remove the entrained extract, and enters the butene-1 refining tower for refining. The butene-1 product is extracted from the top of the tower, and the bottom material returns to the precision distillation tower for refining.

[0059] Compared with the prior art, the present invention has the following beneficial effects:

[0060] The method for producing butene-1 from C4 light hydrocarbons of the present invention adopts a separation method combining ordinary distillation and extractive distillation, and simultaneously separates isobutane and heavy C4 in a precision distillation tower. The flow rate of the butene-1 stream extracted from the side line is small, which reduces the amount of selective hydrogenation catalyst used, reduces the amount of extractant used, and reduces the energy consumption of the subsequent butene-1 processing process, overcomes the shortcomings of the prior art, can achieve a high yield of butene-1 products produced by catalytic C4, and can also obtain high-purity isobutane products. The remaining C4 product is removed from the alkylation device, which improves the utilization of catalytic C4, and through the optimization of the process design, the extractant-poor stream extracted from the desolventizing tower is used as a heat source for the butene-1 tower and the precision distillation tower, reducing steam consumption or only needing to supplement a small amount of steam, improving the economy of the separation device, low production cost, and good economic benefits, that is, it has the characteristics of shortening the process, reducing energy consumption, removing raw material impurities at the same time, strong operability, and high butene-1 yield.

[0061] The selective hydrogenation catalyst of the present invention has high reaction activity and butene-1 selectivity, butene-1 is basically not lost in the hydrogenation process, and under mild conditions, dienes (butadiene and alkynes) react with H2 to generate butene, the hydrogenation position is reasonably selected, and a high butene-1 yield is maintained. The reaction releases a certain amount of heat, and the temperature rise varies with the different butadiene content in the material. The reacted material directly enters the subsequent extraction distillation tower without heat exchange to separate the alkane and alkene carbon four, and the heat of the hydrogenation reaction can be utilized and recovered, thereby reducing the comprehensive energy consumption of the device, and the process is simple and easy to implement. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] In order to more clearly illustrate the technical solution in the present invention, the drawings required for use in the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained without paying creative work.

[0063] Figure 1 The process flow diagram of the method for producing butene-1 from C4 light hydrocarbons of the present invention is shown;

[0064] In the figure, 1. precision distillation tower, 2. hydrogenation reactor, 3. extractive distillation tower, 4. desolventizing tower, 5. water washing tower, 6. butene-1 refining tower, 7. mixed C4, 8. C4 after etherification, 9. C4 light component isobutane stream, 10. Heavy C4 stream, 11. C4 component stream rich in butene-1, 12. Hydrogen stream, 13. Material after hydrogenation, 14. Extractant stream, 15. Isobutane fraction, 16. Rich extractant stream, 17. n-butene stream, 18. Lean extractant stream, 19. n-butene stream after water washing, 20. Extractant-containing water stream, 21. Butene-1 stream, 22. C4 stream containing butene-1, 23. MTBE unit, 24. Water stream. DETAILED DESCRIPTION

[0065] In order to further understand the present invention, preferred embodiments of the present invention are described below. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0066] like Figure 1 As shown, the method for producing butene-1 from C4 light hydrocarbons of the present invention comprises the following steps:

[0067] Step 1, transporting the etherified C4 8 to a precision distillation tower 1, obtaining a C4 light component isobutane stream 9 at the top of the tower, obtaining a heavy C4 stream 10 at the bottom of the tower, and extracting a C4 component stream 11 rich in butene-1 from the side line of the tower;

[0068] Step 2: The C4 component stream 11 rich in butene-1 is combined with the hydrogen stream 12 to enter the hydrogenation reactor 2, and the butadiene component entrained in the C4 component stream 11 rich in butene-1 is removed to obtain a hydrogenated material 13;

[0069] Step 3, transporting the hydrogenated material 13 to the extractive distillation tower 3, extracting and distilling through the extractant stream 14, producing an isobutane fraction 15 at the top of the tower, combining it with the C4 light component isobutane stream 9 produced at the top of the precision distillation tower 1 and delivering it, and producing a rich extractant stream 16 containing a mixed solvent and butene components at the bottom of the tower;

[0070] Step 4: convey the rich extractant stream 16 to the desolventizing tower 4, extract the n-butene stream 17 at the top of the tower, extract the lean extractant stream 18 at the bottom of the tower, and return the lean extractant stream 18 to the extractive distillation tower 3 for reuse after heat recovery;

[0071] Step 5: transport the n-butene stream 17 to the water washing tower 5 for washing to remove the entrained extractant, extract the n-butene stream 19 after washing from the top of the tower, and extractant-containing water stream 20 from the bottom of the tower and transport it to a sewage treatment plant or an extractant recovery device;

[0072] Step six, the washed normal butene stream 19 is transported to the butene-1 refining tower 6, the butene-1 stream 21 is taken out of the tower top and stored in the device, and the C4 stream 22 containing butene-1 (a small amount) is taken out of the tower bottom and returned to the precision distillation tower 1.

[0073] In the above technical solution, in step 1, the source of the etherified C4 8 is not particularly limited, such as transporting the mixed C4 7 to the MTBE device 23, removing isobutylene through etherification reaction, and obtaining the etherified C4 8, or the etherified C4 from steam cracking and coal chemical industry. The source of the mixed C4 7 is not particularly limited, and it can be the mixed C4 by-product of petrochemical refining catalytic cracking, or other sources.

[0074] In the above technical solution, in step 1, the number of theoretical plates of the precision distillation tower 1 is preferably 102, and a side line is usually drawn at 15 to 40 theoretical plates in the tower to obtain a carbon four component stream 11 rich in butene-1, but it should be noted that those skilled in the art can change it according to actual needs. The working conditions of the precision distillation tower 1 are preferably: pressure 0.4 to 2.0 MPa, temperature 40 to 110° C., and reflux ratio 4 to 20.

[0075] In the above technical scheme, in step 2, the working conditions of the hydrogenation reactor are: reaction pressure 1.5MPa, temperature 40-60°C, hydrogen-to-diene ratio 1.1-2.0mol / mol, space velocity 5h -1 .

[0076] In the above technical solution, in step 3, the number of theoretical plates of the extractive distillation tower 3 is preferably 95, and the extractant stream 14 includes acetonitrile, DMF or N-methylpyrrolidone, which is added at 5 to 10 theoretical plates, but it should be noted that those skilled in the art can change it according to actual needs. The working conditions of the extractive distillation tower 3 are preferably: pressure 0.4 to 0.7 MPa, reflux ratio 1 to 5, and solvent ratio 2 to 10.

[0077] In the above technical solution, in step 4, the theoretical number of plates of the desolventizing tower 4 is preferably 22, but it should be noted that those skilled in the art can change it according to actual needs. The working conditions of the desolventizing tower 4 are preferably: pressure 0.4-0.7MPa, reflux ratio 1-5.

[0078] In the above technical solution, in step 5, the n-butene stream 17 enters from the bottom of the water washing tower 5, and the water stream 24 enters from the top of the water washing tower 5, preferably with an oil-water ratio of 1 to 20: 1. The heat of the lean extractant stream 18 is used for the butene-1 tower 6 and the precision distillation tower 1.

[0079] In the above technical solution, in step six, the working conditions of the butene-1 refining tower 6 are preferably: pressure 0.4-0.7 MPa, reflux ratio 1-5.

[0080] The above method for producing butene-1 from C4 light hydrocarbons overcomes the shortcomings of the prior art, such as the long process or high energy consumption, and can achieve high-yield separation of butene-1 products, and can also obtain isobutane products with higher purity. The remaining C4 products are removed from the alkylation device, thereby improving the utilization of catalytic C4. Moreover, by optimizing the process design, part of the waste heat of the extractant is effectively utilized, thereby improving the economic efficiency.

[0081] On this basis, in order to further improve the efficiency of the hydrogenation reaction, the present embodiment provides a selective hydrogenation catalyst used in a hydrogenation reactor 2, comprising a carrier, and a main hydrogenation active component, a first auxiliary active component and a second auxiliary active component loaded on the carrier; the carrier comprises one or both of aluminum oxide and silicon oxide, the main hydrogenation active component is a mixture of one or more of Group VIII metal elements, the first auxiliary active component is a mixture of one or more of Group IA metal elements, and the second auxiliary active component is a mixture of one or more of Group IB metal elements.

[0082] Preferably, the carrier is composed of 80-95 wt% α-phase alumina and 5-20 wt% θ-phase alumina; the specific surface area of ​​the carrier is 20-300 m 2 / g, the specific pore volume is 0.2-0.8 ml / g, the pore radius is 5.0-15 nm; the specific surface area is particularly preferred to be 50-150 m 2 / g.

[0083] Preferably, the main active component of hydrogenation is one of Ni and Pd or a mixture of the two, with Pd having the best effect. The content of the main active component of hydrogenation on the carrier is 0.05-0.5% (m / m), and particularly preferably 0.1-0.3% (m / m).

[0084] Preferably, the first auxiliary active component is one of K and Na or a mixture of the two. The content of the first auxiliary active component on the carrier is 0.05-3.0% (m / m), and particularly preferably 0.1-2.0% (m / m).

[0085] Preferably, the second auxiliary active component is Ag, and the content of the second auxiliary active component on the carrier is 0.05-4.0% (m / m), particularly preferably 0.1-3.0% (m / m).

[0086] The preparation method of the above selective hydrogenation catalyst is:

[0087] First, the raw material of the carrier is mixed evenly with the aqueous solution of the soluble salt of the first auxiliary active component, and after kneading, molding and drying, it is roasted at 400-1200°C for 2-16 hours to obtain the carrier loaded with the first auxiliary active component; then the carrier loaded with the first auxiliary active component is first immersed in the aqueous solution of the soluble salt of the hydrogenation main active component, and after the solution becomes transparent, it is immersed in the aqueous solution of the soluble salt of the second auxiliary active component, and after the solution becomes transparent, it is filtered, or the carrier loaded with the first auxiliary active component is immersed in the aqueous solution containing the soluble salt of the hydrogenation main active component and the soluble salt of the second auxiliary active component, and after the solution becomes transparent, it is filtered; finally, it is dried and roasted at 300-600°C for 3-6 hours to obtain the selective hydrogenation catalyst.

[0088] Preferably, the raw material of the carrier is firstly mixed with the aqueous solution of the soluble salt of the first co-active component, and one or both of a binder and a pore expander are added and mixed evenly, the amount of the pore expander added is 1-4wt% of the raw material of the carrier, and the amount of the binder added is 1-5wt% of the raw material of the carrier, preferably 1-2wt%; most preferably, the binder is sesbania powder and the pore expander is citric acid;

[0089] Preferably, a competitive adsorbent is added to the aqueous solution of the soluble salt of the main hydrogenation active component or the aqueous solution containing the soluble salt of the main hydrogenation active component and the soluble salt of the second auxiliary active component, the competitive adsorbent is an organic acid or an inorganic acid, the organic acid is formic acid, acetic acid or oxalic acid, the inorganic acid is nitric acid or hydrochloric acid, and the amount of the competitive adsorbent is 1.0 to 10.0 wt% of the soluble salt of the main hydrogenation active component;

[0090] Preferably, the immersion temperature is room temperature to 100°C, and the drying temperature is 100 to 300°C.

[0091] Preferably, the soluble salts are independently nitrates or chlorides of the corresponding elements.

[0092] The terms used in the present invention generally have the meanings commonly understood by those of ordinary skill in the art, unless otherwise specified.

[0093] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below in conjunction with embodiments.

[0094] In the following examples, various processes and methods not described in detail are conventional methods known in the art. Unless otherwise specified, the materials, reagents, devices, instruments, equipment, etc. used in the following examples can be obtained from commercial sources.

[0095] Example 1

[0096] Preparation of Selective Hydrogenation Catalysts:

[0097] Step 1: first add 5wt% sesbania powder to the boehmite powder and mix evenly, then add 10wt% citric acid aqueous solution (the amount of citric acid is 2wt% of the boehmite powder), then add potassium nitrate aqueous solution (the amount of potassium nitrate is 2wt% of the boehmite powder), knead and extrude to form a preform with a diameter of 1.5-3mm strip or 2-4mm sphere, first dry at room temperature for 24h, then dry at 120℃ for 4h, then keep constant temperature at 500℃ for 1h, finally keep constant temperature at 1100℃ for 4h, and naturally cool to obtain a carrier loaded with the first auxiliary active component. After testing, the carrier has the following properties: crystal phase: α phase is the main phase; specific pore volume: 0.3-0.5ml / g; specific surface area: 100-150m 2 / g.

[0098] Step 2, weigh the chloropalladic acid powder with Pd content not less than 59.5% according to the catalyst Pd content requirement, dissolve in distilled water, and prepare PdCl2 aqueous solution. According to the catalyst Ag content requirement, weigh the silver nitrate powder with Ag content not less than 64.0%, dissolve in distilled water, and prepare AgNO3 aqueous solution. Under room temperature~100 ℃ condition, the carrier of the first active component of the load prepared in step 1 is immersed in PdCl2 aqueous solution, and stirred evenly in the impregnation solution at the same time, so that the active component is evenly distributed on the surface of the carrier, and the remaining liquid is filtered out after the solution becomes colorless and transparent, and then immersed in AgNO3 aqueous solution at room temperature, and the remaining liquid is filtered out after the solution becomes transparent, first dried at 120 ℃ for 2h, then dried at 120 ℃ for 2h, and finally roasted at 500 ℃ for 6h to make a selective hydrogenation catalyst. After testing, the content of Pd on the carrier is 0.3% (m / m), and the Ag content is 0.3% (m / m).

[0099] Example 2

[0100] like Figure 1 As shown, the method for producing butene-1 from C4 light hydrocarbons comprises the following steps:

[0101] Step 1: transporting the mixed C4 7 produced by catalytic cracking in the refinery to the MTBE unit 23, removing isobutylene through an etherification reaction, and obtaining etherified C4 8;

[0102] Step 2, transport the etherified C4 8 to a precision distillation tower 1, the precision distillation tower 1 has 102 theoretical plates, and the working conditions are: pressure 0.5 MPa, temperature at the top of the tower 45°C, tower bottom 58°C, reflux ratio 10, obtain C4 light component isobutane stream 9 at the top of the tower, obtain heavy C4 stream 10 at the bottom of the tower, and extract the side line at 30 theoretical plates in the tower to obtain a C4 component stream 11 rich in butene-1;

[0103] Step 3: The C4 stream 11 rich in butene-1 and the hydrogen stream 12 are combined and fed into the hydrogenation reactor 2 (loaded with the selective hydrogenation catalyst of Example 1), and the butadiene component entrained in the C4 stream 11 rich in butene-1 is removed to obtain the hydrogenated material 13; the hydrogenation operation condition is a space velocity of 5h -1 , temperature 40°C, pressure 1.5MPa, hydrogen-to-diene ratio 1.3mol / mol;

[0104] Step 4, transporting the hydrogenated material 13 to the extractive distillation tower 3, extracting and distilling through the extractant stream 14 (acetonitrile), the extractive distillation tower 3 has 95 theoretical plates, the extractant stream 14 is added from 5 theoretical plates, the working conditions are: pressure 0.5 MPa, reflux ratio 3, solvent ratio 10, isobutane fraction 15 is produced at the top of the tower, combined with the carbon four light component isobutane stream 9 produced from the top of the precision distillation tower 1 and sent out, and the rich extractant stream 16 containing mixed solvent and butene component is produced at the bottom of the tower;

[0105] Step 5, conveying the rich extractant stream 16 containing the mixed solvent and the butene component to the desolventizing tower 4, the desolventizing tower has 22 theoretical plates, and the working conditions are: pressure 0.5 MPa, reflux ratio 2, taking out the n-butene stream 17 at the top of the tower, taking out the lean extractant stream 18 at the bottom of the tower, and returning the lean extractant stream 18 to the extractive distillation tower 3 for reuse after heat recovery;

[0106] Step 6: transport the n-butene stream 17 to the water washing tower 5 for washing to remove the entrained extractant. The n-butene stream 17 enters the water washing tower 5 from the bottom, and the water stream 24 enters the water washing tower 5 from the top. The oil-water ratio is 1-20:1. The n-butene stream 19 after washing is produced from the top of the tower, and the water stream 20 containing the extractant is produced from the bottom of the tower and transported to a sewage treatment plant or an extractant recovery device.

[0107] Step 7, the normal butene stream 19 after water washing is transported to the butene-1 refining tower 6, working conditions: pressure 0.5MPa, reflux ratio 2, butene-1 stream 21 taken out of the top of the tower is stored in the device, and the carbon four stream 22 containing butene-1 is taken out of the bottom of the tower and returned to the precision distillation tower 1.

[0108] The operating results of the method for producing butene-1 from C4 light hydrocarbons in Example 2 are shown in Table 1.

[0109] Table 1 Material data sheet

[0110] composition 7 8 9 10 11 15 17 19 20 21 22 Isobutane 43.57 50.00 96.04 0.00 57.41 95.72 0 0 0 0 0 n-Butane 17.43 20.00 0 49.82 0.36 0.60 0 0 0 0 0 Butene-1 8.71 10.00 3.89 0.61 40.60 0.14 96.22 98.65 1.49 99.34 12.73 Isobutylene 13.00 0.15 0.07 0 0.60 0.67 0.45 0.46 0 0.46 0.23 Trans-Butene-2 10.50 12.05 0 30.06 0.14 0 0.32 0.33 0 0.19 17.92 Cis-2-Butene 6.60 7.60 0 19.49 0.02 0 0.04 0.04 0 0.02 3.50 Butadiene 0.17 0.2 0.03 0.02 0.87 0 0 0 0 0 0 water 0 0 0 0 0 0 0 0.13 95.85 0 16.27 Extraction solvent 0 0 0 0 2.88 2.97 0.39 2.65 0 49.36 Flow rate kg / hr 1129 1000 400 400 200 121 85 81.6 83.4 81 0.6

[0111] The selective hydrogenation catalyst of Example 1 was used and the hydrogenation operation condition was a space velocity of 5h -1 Under the conditions of temperature 40°C, pressure 1.5 MPa and hydrogen-to-diene ratio of 1.3 mol / mol, the material composition before and after hydrogenation operation is shown in Table 2 below.

[0112] Table 2 Material composition before and after hydrogenation operation

[0113] composition Isobutane n-Butane Butene-1 Isobutylene Trans-Butene-2 Cis-2-Butene Butadiene raw material 43.57 17.43 8.71 13.00 10.5 6.6 0.17 product 43.57 17.43 8.70 13.01 10.56 6.71 0.0004

[0114] Comparative Example 1

[0115] Example 1 in CN102992933A

[0116] It can be seen from the effect data of Example 2 and Comparative Example 1 that the method of the present invention simultaneously separates isobutane and heavy carbon four into two products in the precision distillation tower 1, and the flow rate of the butene-1 stream extracted from the side line is small, which reduces the amount of selective hydrogenation catalyst used, reduces the amount of extractant used, and reduces the energy consumption of the subsequent butene-1 processing process. The lean solvent extracted from the bottom of the extraction solvent tower 3 can be used as a heat source for the butene-1 tower 6 and the precision distillation tower 1, reducing steam consumption or only requiring a small amount of steam to be supplemented, with low production costs and good economic benefits.

[0117] In particular, the selective hydrogenation catalyst of Example 1 has high reaction activity and butene-1 selectivity, butene-1 is basically not lost during the hydrogenation process, the hydrogenation position is reasonably selected, and the heat of the hydrogenation reaction can be utilized while removing butadiene. The process is simple and easy to implement.

[0118] Obviously, the above embodiments are merely examples for clear explanation, and are not intended to limit the embodiments. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. The obvious changes or modifications derived from them are still within the protection scope of the invention.

Claims

1. A method for producing butene-1 from C4 light hydrocarbons, characterized in that: The following steps are involved: Step 1, transporting the etherified C4 (8) to a precision distillation tower (1), obtaining a C4 light component isobutane stream (9) at the top of the tower, obtaining a heavy C4 stream (10) at the bottom of the tower, and extracting a C4 component stream (11) rich in butene-1 from a side line in the tower; Step 2: Combine the C4 stream (11) rich in butene-1 and the hydrogen stream (12) and transport them to the hydrogenation reactor (2), remove butadiene entrained in the C4 stream (11) rich in butene-1, and obtain a hydrogenated material (13); Step 3, transporting the hydrogenated material (13) to an extractive distillation tower (3), extracting and distilling through an extractant stream (14), producing an isobutane fraction (15) at the top of the tower, combining it with the C4 light component isobutane stream (9) produced from the top of the precision distillation tower (1) and delivering it, and producing a rich extractant stream (16) containing a mixed solvent and butene at the bottom of the tower; Step 4: conveying the rich extractant stream (16) to the desolventizing tower (4), extracting the n-butene stream (17) at the top of the tower, extracting the lean extractant stream (18) at the bottom of the tower, and returning the lean extractant stream (18) to the extractive distillation tower (3) for reuse after heat recovery; Step 5: conveying the n-butene stream (17) to a water washing tower (5) to remove the entrained extractant by water washing, taking out the washed n-butene stream (19) from the top of the tower, and taking out the extractant-containing water stream (20) from the bottom of the tower and conveying it to a sewage treatment plant or an extractant recovery device; Step 6. The water-washed normal butene stream (19) is transported to a butene-1 refining tower (6), a butene-1 stream (21) is taken out from the top of the tower and stored, and a C4 stream (22) containing butene-1 is taken out from the bottom of the tower and combined with new post-ether C4 (8) and transported to a precision distillation tower (1).

2. A method for producing butene-1 from C4 light hydrocarbons according to claim 1, characterized in that: In step 1, the process for obtaining the etherified C4 (8) is as follows: the mixed C4 (7) is transported to the MTBE device (23), and isobutylene is removed by etherification reaction to obtain the etherified C4 (8).

3. The method for producing butene-1 from C4 light hydrocarbons according to claim 1, characterized in that: In step 1, the number of theoretical plates of the precision distillation tower (1) is 102, and a side line is drawn at 15 to 40 theoretical plates in the tower to obtain a C4 stream (11) rich in butene-1; The working conditions of the precision distillation tower (1) are: pressure 0.4-2.0 MPa, temperature 40-110° C., and reflux ratio 4-20.

4. The method for producing butene-1 from C4 light hydrocarbons according to claim 1, characterized in that: Step 2: The selective hydrogenation catalyst used in the hydrogenation reactor (2) comprises a carrier, a main hydrogenation active component, a first auxiliary active component and a second auxiliary active component; The carrier is one or more of aluminum oxide and silicon oxide; the main active component of hydrogenation is a mixture of one or more of Group VIII metal elements; the first auxiliary active component is a mixture of one or more of Group IA metal elements; and the second auxiliary active component is a mixture of one or more of Group IB metal elements.

5. A method for producing butene-1 from C4 light hydrocarbons according to claim 4, characterized in that: The carrier is composed of 80-95 wt% of α-phase alumina and 5-20 wt% of θ-phase alumina, and the specific surface area of ​​the carrier is 20-300 m 2 / g, specific pore volume is 0.2~0.8ml / g, pore radius is 5.0~15nm; The main hydrogenation active component is one of Ni and Pd or a mixture of the two, and the mass percentage of the main hydrogenation active component on the carrier is 0.05-0.5%; The first auxiliary active component is one of K and Na or a mixture of the two, and the mass percentage of the first auxiliary active component on the carrier is 0.05-3.0%; The second auxiliary active component is Ag, and the mass percentage of the second auxiliary active component on the carrier is 0.05-4.0%.

6. A method for producing butene-1 from C4 light hydrocarbons according to claim 4, characterized in that: The preparation method of the selective hydrogenation catalyst is: First, the raw material of the carrier is mixed evenly with the aqueous solution of the soluble salt of the first auxiliary active component, and after kneading, molding and drying, it is roasted at 400-1200°C for 2-16 hours to obtain the carrier loaded with the first auxiliary active component; then the carrier loaded with the first auxiliary active component is first immersed in the aqueous solution of the soluble salt of the hydrogenation main active component, and after the solution becomes transparent, it is immersed in the aqueous solution of the soluble salt of the second auxiliary active component, and after the solution becomes transparent, it is filtered, or the carrier loaded with the first auxiliary active component is immersed in the aqueous solution containing the soluble salt of the hydrogenation main active component and the soluble salt of the second auxiliary active component, and after the solution becomes transparent, it is filtered; finally, it is dried and roasted at 300-600°C for 3-6 hours to obtain the selective hydrogenation catalyst.

7. A method for producing butene-1 from C4 light hydrocarbons according to claim 6, characterized in that: First, the raw material of the carrier and the aqueous solution of the soluble salt of the first co-active component are mixed evenly, and one or both of a binder and a pore expander are added and mixed evenly, wherein the amount of the pore expander added is 1-4wt% of the raw material of the carrier, and the amount of the binder added is 1-5wt% of the raw material of the carrier, the binder is sesbania powder, and the pore expander is citric acid; The drying temperature is 100-300°C; A competitive adsorbent is further added to the aqueous solution of the soluble salt of the main hydrogenation active component or the aqueous solution containing the soluble salt of the main hydrogenation active component and the soluble salt of the second auxiliary active component, wherein the competitive adsorbent is an organic acid or an inorganic acid, wherein the organic acid is formic acid, acetic acid or oxalic acid, and the inorganic acid is nitric acid or hydrochloric acid, and the amount of the competitive adsorbent is 1.0 to 10.0 wt% of the soluble salt of the main hydrogenation active component; The immersion temperature is respectively room temperature to 100°C; The soluble salts are independently nitrates or chlorides of the corresponding elements.

8. The method for producing butene-1 from C4 light hydrocarbons according to claim 1, characterized in that: In step 2, the working conditions of the hydrogenation reactor (2) are: reaction pressure 1.5 MPa, temperature 40-60°C, hydrogen-to-diene ratio 1.1-2.0 mol / mol, space velocity 5h -1 ; In step 3, the number of theoretical plates of the extractive distillation tower (3) is 95, and the extractant stream (14) includes acetonitrile, DMF or N-methylpyrrolidone, which is added at 5 to 10 theoretical plates; The working conditions of the extractive distillation tower (3) are: pressure 0.4-0.7 MPa, reflux ratio 1-5, and solvent ratio 2-10.

9. The method for producing butene-1 from C4 light hydrocarbons according to claim 1, characterized in that: In step 4, the number of theoretical plates of the desolventizing tower (4) is 22; The working conditions of the desolventizing tower (4) are: pressure 0.4-0.7 MPa, reflux ratio 1-5.

10. The method for producing butene-1 from C4 light hydrocarbons according to claim 1, characterized in that: In step 5, the n-butene stream (17) enters from the bottom of the water washing tower (5), and the water stream (24) enters from the top of the water washing tower (5), with an oil-water ratio of 1 to 20:1; The heat of the lean extractant stream (18) is used in the butene-1 column (6) and the fine distillation column (1); In step six, the working conditions of the butene-1 refining tower (6) are: pressure 0.4-0.7 MPa, reflux ratio 1-5.

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