Method for co-producing olefin and aromatic hydrocarbon

Abstract

The invention relates to the technical field of conversion of C5-C7 alkanes in petrochemical industry into olefins and aromatic hydrocarbons, in particular to a method for co-production of olefins and aromatic hydrocarbons, which comprises the following steps: (1) in the presence of a first dehydrogenation catalyst, carrying out a first reaction on a first raw material flow containing C5 alkanes to obtain a first product flow containing hydrogen, C5 alkanes and C5 olefins; (2) in the presence of a second dehydrogenation catalyst, carrying out a second reaction on the first product material flow and a second raw material flow containing C6-C7 alkane to obtain a second product material flow containing hydrogen, C5-C7 alkane, C5-C7 olefin, benzene and toluene; and (3) carrying out product separation treatment on the second product flow to obtain C5-C7 olefin, benzene and toluene, wherein the temperature of the second reaction is 10-60 DEG C lower than that of the first reaction. The method realizes co-production of olefin and aromatic hydrocarbon by using C5-C7 alkane with low added value, and has high total yield of olefin and aromatic hydrocarbon.

Description

Technical Field

[0001] The present invention relates to the technical field of converting C5-C7 alkanes into olefins and aromatics in petrochemical industry, and in particular to a method for co-producing olefins and aromatics. Background Art

[0002] The products of catalytic reforming process contain a large amount of BTX and C9 + In addition to aromatics, a certain amount of low-value C5-C7 alkanes is present. These C5-C7 alkanes are mostly straight-chain and singly branched, with low octane numbers, making them a suboptimal gasoline pool component. While n-pentane, a promising cracking feedstock, can be used in the steam cracking process to produce ethylene and propylene, the remaining C5-C6 alkanes enter the isomerization unit to produce multi-branched isoparaffins, ultimately entering the gasoline pool. However, with the improvement of domestic gasoline quality standards and the continuous decline in saturated vapor pressure, the low-boiling-point C5-C6 fraction is becoming difficult to enter the gasoline pool. Due to the kinetics and thermodynamics of the reforming reaction, C7 alkanes are inherently difficult to convert into aromatics, and a suitable disposal option has been lacking.

[0003] Therefore, the development of new C5-C7 alkane utilization technologies is of great significance for expanding the utilization channels of low-value-added C5-C7 alkanes. Summary of the Invention

[0004] The present invention addresses the problem that C5-C7 alkanes are difficult to utilize with high added value, and provides a method for co-producing olefins and aromatics, thereby realizing the conversion of C5-C7 alkanes into olefins and aromatics.

[0005] In order to achieve the above object, the present invention provides a method for co-producing olefins and aromatics, the method comprising:

[0006] (1) subjecting a first feed stream containing C5 alkanes to a first reaction in the presence of a first dehydrogenation catalyst to obtain a first product stream containing hydrogen, C5 alkanes, and C5 olefins;

[0007] (2) subjecting the first product stream and a second feed stream containing C6-C7 alkanes to a second reaction in the presence of a second dehydrogenation catalyst to obtain a second product stream containing hydrogen, C5-C7 alkanes, C5-C7 olefins, benzene, and toluene;

[0008] (3) subjecting the second product stream to product separation to obtain C5-C7 olefins, benzene, and toluene;

[0009] The temperature of the first reaction is 10-60° C. higher than the temperature of the second reaction.

[0010] Through the above technical solution, the present invention adopts a method of feeding C5 alkanes and C6-C7 alkanes separately, wherein the difficult-to-dehydrogenate C5 alkanes are first dehydrogenated under conditions of high catalytic activity, and then the dehydrogenated products of the C5 alkanes are dehydrogenated, cyclized, and metathesized together with the relatively easy-to-dehydrogenate C6-C7 alkanes under conditions of relatively low catalytic activity (reaction temperature is 10-60°C lower than the dehydrogenation temperature of the C5 alkanes). After that, the products are separated to obtain C5-C7 olefins, benzene, and toluene, thereby achieving the co-production of olefins and aromatics. The method for co-producing olefins and aromatics provided by the present invention has high raw material utilization, can achieve high production of olefins and aromatics products under relatively mild reaction conditions, and achieve a total yield of olefins and aromatics greater than 38%, preferably, a total yield of olefins greater than 42%. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 The present invention is a process flow chart for the co-production of olefins and aromatics according to a preferred embodiment of the present invention.

[0012] Figure 2 yes Figure 1 Schematic diagram of the composition of the first reaction zone, the second reaction zone and the catalyst regeneration unit.

[0013] Description of Reference Numerals

[0014] 1. First reaction zone 2, second reaction zone 3, raw material pretreatment unit

[0015] 4. Catalyst regeneration unit 5. Compression cooling unit 6. Distillation unit

[0016] 7. C5 olefin separation unit 8. Aromatic hydrocarbon separation unit 9. C6-C7 olefin separation unit

[0017] 10. First feed stream containing C5 alkanes 11. Second feed stream containing C6-C7 alkanes

[0018] 12. First product stream containing hydrogen, C5 alkanes and C5 olefins 13. Mixed stream

[0019] 14. A second product stream containing hydrogen, C5-C7 alkanes, C5-C7 olefins, benzene and toluene

[0020] 15. Gas phase logistics containing hydrogen 16. Liquid phase logistics 17. Logistics containing C5 components

[0021] 18. Logistics containing C6-C7 components 19. C5 olefins 20. C5 alkane product logistics

[0022] 21. Aromatics logistics 22. Dearomatization logistics 23. C6-C7 olefins

[0023] 24. C6-C7 alkane product stream 25. Heavy component C8 + Hydrocarbon Logistics

[0024] 26, first reactor 27, second reactor 28, third reactor

[0025] 29, fourth reactor 30, first buffer hopper 31, second buffer hopper

[0026] 32. Third buffer hopper 33. Fourth buffer hopper 34. First collector

[0027] 35, second collector 36, third collector 37, fourth collector

[0028] 38. Regenerator 39. Separation hopper 40. Regenerated catalyst collector DETAILED DESCRIPTION

[0029] The endpoints of the ranges and any values ​​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 endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0030] The following is a detailed description of the specific embodiments of the present invention. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0031] The present invention provides a method for co-producing olefins and aromatics, the method comprising:

[0032] (1) subjecting a first feed stream containing C5 alkanes to a first reaction in the presence of a first dehydrogenation catalyst to obtain a first product stream containing hydrogen, C5 alkanes, and C5 olefins;

[0033] (2) subjecting the first product stream and a second feed stream containing C6-C7 alkanes to a second reaction in the presence of a second dehydrogenation catalyst to obtain a second product stream containing hydrogen, C5-C7 alkanes, C5-C7 olefins, benzene, and toluene;

[0034] (3) subjecting the second product stream to product separation to obtain C5-C7 olefins, benzene, and toluene;

[0035] The temperature of the first reaction is 10-60° C. higher than the temperature of the second reaction.

[0036] The present invention performs the reaction by feeding C5 alkanes and C6-C7 alkanes in C5-C7 alkanes separately, and matches the different difficulty levels of the dehydrogenation reactions of C5-C7 alkanes. First, the C5 alkanes that are difficult to dehydrogenate are dehydrogenated under conditions of relatively high catalytic activity. Then, the dehydrogenation products of the C5 alkanes are jointly subjected to dehydrogenation, cyclization, metathesis and other reactions with the C6-C7 alkanes that are relatively easy to dehydrogenate under conditions of relatively low catalytic activity. This is conducive to achieving high production of olefins and aromatic products under relatively mild reaction conditions.

[0037] According to the present invention, the C5-C7 alkane refers to a straight-chain or monobranched alkane having 5 to 7 carbon atoms. The present invention does not particularly limit the source of the C5-C7 alkane. For example, the C5 alkane may be light naphtha from a reformer or pentane oil from a reformer, and the C6-C7 alkane may be raffinate oil or distillate naphtha from an extraction unit.

[0038] According to the present invention, in the method for co-producing olefins and aromatics, in step (1), preferably, the content of C5 alkanes in the first C5 alkane-containing feed stream is ≥ 85 wt%, which facilitates controlling reaction conditions and ensuring the subsequent product separation effect. Further preferably, the content of C5 alkanes in the first C5 alkane-containing feed stream is 92-99 wt%.

[0039] According to the present invention, in step (1), the first reaction is a dehydrogenation reaction. Under the action of the first dehydrogenation catalyst, the C5 alkanes in the first feed stream are dehydrogenated to obtain product hydrogen and C5 olefins.

[0040] In the present invention, the first product stream contains, in addition to the dehydrogenation product hydrogen and C5 olefins, unreacted C5 alkanes and a small amount of C1-C4 light hydrocarbon products produced by side reactions.

[0041] According to the present invention, in step (1), considering that the dehydrogenation difficulty of the C5 alkane is relatively high and a higher reaction temperature is required to achieve the dehydrogenation effect, the first reaction is carried out under relatively high catalytic activity conditions. Preferably, the conditions of the first reaction include: a temperature of 480-580°C; a pressure of 0.01-1 MPa; a hydrogen-to-hydrocarbon molar ratio of (0.1-10):1; a mass space velocity of 1-6 h-1 / 2 of the first feed stream containing C5 alkane; -1 .

[0042] According to the present invention, in step (1), in order to make the first dehydrogenation catalyst show better catalytic activity in the first reaction and achieve the purpose of maximizing the yield of C5 olefins, the first reaction is further preferably carried out at 520-580°C.

[0043] According to the present invention, in the method for co-producing olefins and aromatics, in step (2), preferably, the total content of C6 and C7 alkanes in the second feed stream containing C6-C7 alkanes is ≥ 90 wt%, which facilitates controlling reaction conditions and ensuring the subsequent product separation effect. Further preferably, the total content of C6 and C7 alkanes in the second feed stream containing C6-C7 alkanes is 95-99 wt%.

[0044] According to the present invention, in step (2), the first product stream and the second feed stream are jointly subjected to the second reaction. Preferably, before the second reaction, the first product stream and the second feed stream are mixed and fed as a mixed material to the second reaction.

[0045] According to the present invention, in step (2), preferably, the weight ratio of the first feed stream containing C5 alkanes to the second feed stream containing C6-C7 alkanes is controlled to be 1:(2-8), which is conducive to obtaining a higher total yield of olefins and aromatics. Further preferably, the weight ratio of the first feed stream containing C5 alkanes to the second feed stream containing C6-C7 alkanes is 1:(3-6).

[0046] According to the present invention, in step (2), the second reaction includes dehydrogenation, cyclization, and metathesis reactions. Under the action of the second dehydrogenation catalyst, the C6-C7 alkanes in the second feed stream undergo dehydrogenation and cyclization reactions, the unreacted C5 alkanes in the first product stream undergo dehydrogenation reactions, and some C5 olefins (including C5 olefins produced by the first reaction and C5 olefins produced by the second reaction) undergo dehydrogenation, cyclization, and metathesis reactions with the C7 olefins obtained by the dehydrogenation of the C7 alkanes. After the second reaction, hydrogen, C5-C7 olefins, benzene, and toluene are obtained as products.

[0047] In the present invention, the second product stream contains not only product hydrogen, C5-C7 olefins, benzene and toluene, but also unreacted C5-C7 alkanes, a small amount of C1-C4 light hydrocarbon products and C8 + By-products such as hydrocarbons.

[0048] According to the present invention, in step (2), considering that the dehydrogenation difficulty of the C6-C7 alkane is smaller than that of the C5 alkane, the dehydrogenation and cyclization reaction of the C6-C7 alkane does not require an excessively high reaction temperature, so the second reaction is carried out under relatively low catalytic activity conditions. Preferably, the conditions of the second reaction include: a temperature of 440-540°C, preferably 500-540°C; a pressure of 0.01-1MPa; a hydrogen-to-hydrocarbon molar ratio of (0.1-10):1; a total mass space velocity of 1-6h-1 of the first product stream and the second feed stream containing C6-C7 alkane. -1 .

[0049] According to the present invention, preferably, the temperature of the second reaction is controlled to be 20-40°C lower than the temperature of the first reaction, which is beneficial to better suppress the side reactions such as cracking and hydrogenolysis of the C6-C7 alkanes, resulting in higher selectivity of olefins and aromatics.

[0050] According to the present invention, in step (1) and step (2), the first reaction and the second reaction are preferably carried out in a moving bed multi-stage series reaction mode, and the first reaction and the second reaction are carried out in sequence in multiple moving bed reactors. Using this reaction mode, the catalyst will sequentially enter multiple reactors in series (i.e., participate in the first reaction and the second reaction in sequence). In the process of sequentially entering multiple reactors in series, as the reaction proceeds, the activity of the catalyst gradually decreases, thereby matching the difficulty level of the C5-C7 alkane dehydrogenation reaction. Preferably, the first reaction can adopt one reactor or two reactors in series, and the second reaction can adopt 2-4 reactors in series.

[0051] According to the present invention, in step (1) and step (2), the first dehydrogenation catalyst and the second dehydrogenation catalyst can be conventional alkane dehydrogenation catalysts, which can be obtained through commercial channels or homemade. In the present invention, preferably, the first dehydrogenation catalyst and the second dehydrogenation catalyst each independently include a carrier and an active component;

[0052] Wherein, based on the total weight of the carrier, the active components include: 0.1-2 wt% of Group VIII metal, 0.1-2 wt% of Group IIIA and / or Group IVA metal, 0.5-5 wt% of Group IA metal, 0.3-10 wt% of halogen, 0.1-1 wt% of Eu and 0.1-1 wt% of Ce;

[0053] The carrier is selected from at least one of aluminum oxide, silicon oxide, zirconium oxide and titanium oxide.

[0054] According to the present invention, in the first and second dehydrogenation catalysts, preferably, the Group VIII metal is selected from Pt and / or Pd; the Group IIIA and / or Group IVA metal is selected from at least one of Ge, Sn, Pb, Ga, In, and Tl, more preferably at least one of Sn, Ga, and In; and the Group IA metal is selected from Na and / or K, more preferably K. Using these preferred active components, the first and second dehydrogenation catalysts can exhibit enhanced dehydrogenation and dehydrocyclization activities.

[0055] According to the present invention, in the first dehydrogenation catalyst and the second dehydrogenation catalyst, the carrier is preferably alumina, and more preferably θ-alumina.

[0056] According to the present invention, preferably, the specific surface area of ​​the first dehydrogenation catalyst and the second dehydrogenation catalyst is 50-130m 2 / g, pore volume of 0.5-1cm 3 / g, thereby bringing better dehydrogenation and dehydrocyclization activity.

[0057] In the present invention, the specific surface area and pore volume of the catalyst are measured using the BET method.

[0058] According to the present invention, the first catalyst and the second catalyst are independent of each other in composition and can be the same or different. From the perspectives of process control and operating costs, it is preferred that the first catalyst and the second catalyst are the same.

[0059] In the present invention, the first dehydrogenation catalyst and the second dehydrogenation catalyst can be prepared by a conventional method for preparing a supported catalyst. According to a preferred embodiment of the present invention, the catalyst can be prepared by the following method:

[0060] (a) mixing an alumina sol with a hydrochloric acid solution containing SnCl2, EuCl3, and CeCl3 and a urea solution, and then adding kerosene and fatty alcohol polyoxyethylene ether to obtain a mixed sol; and performing drop ball forming on the mixed sol to obtain a solid product;

[0061] The solid product is solidified in an aqueous ammonia phase, followed by washing, drying, a first calcination, a steam treatment, and a second calcination to obtain a spherical alumina support containing Sn, Eu, and Ce;

[0062] (b) impregnating the spherical alumina support containing Sn, Eu, and Ce with an impregnation solution containing chloroplatinic acid and hydrochloric acid, and then drying and calcining the impregnated support to obtain a calcined product;

[0063] (c) impregnating the calcined product with an alkali solution, and then drying the impregnated calcined product to obtain an alkali-impregnated and dried solid;

[0064] (d) subjecting the dried solid impregnated with alkali to oxychlorination treatment with air containing water and HCl, and then subjecting it to hydrogen reduction to obtain the catalyst.

[0065] Wherein, in step (a), the temperature of the first calcination is 450-700°C, and the time of the first calcination is 1-10 hours; the temperature of the steam treatment is 400-700°C, and the treatment time is 0.5-2 hours; the temperature of the second calcination is 800-1150°C, and the time of the second calcination is 1-10 hours;

[0066] In step (b), the impregnation temperature is 20-35°C, and the impregnation time is 1-10 hours; the drying temperature is 80-150°C, and the drying time is 5-20 hours; the roasting temperature is 450-550°C, and the roasting time is 1-8 hours;

[0067] In step (c), the alkaline solution is preferably an aqueous solution of NaOH and / or KOH; the immersion temperature is 20-35°C, and the immersion time is 1-10 hours; the drying temperature is 80-130°C, and the drying time is 1-20 hours;

[0068] In step (d), the temperature of the oxychlorination treatment is 500-700° C., and the treatment time is 1-8 hours;

[0069] In the above steps, the feeding amount of each raw material is such that, in the catalyst, based on the total weight of the alumina carrier, the active components include: 0.1-2wt% Pt, 0.1-2wt% Sn, 0.5-5wt% K, 0.3-10wt% Cl, 0.1-1wt% Eu and 0.1-1wt% Ce.

[0070] According to the present invention, in the method for co-producing olefins and aromatics, in step (3), the product separation process comprises:

[0071] (i) compressing, cooling, and separating the second product stream in sequence to obtain a liquid stream and a hydrogen-containing gaseous stream;

[0072] (ii) fractionating the liquid phase stream to obtain a stream containing C5 components and a stream containing C6-C7 components;

[0073] (iii) subjecting the C5 component-containing stream to a first alkane-olefin separation to obtain a C5 alkane product stream and C5 olefins;

[0074] The C6-C7 component-containing stream is subjected to aromatic separation to obtain a dearomatized stream, benzene and toluene; and then the dearomatized stream is subjected to a second alkane-olefin separation to obtain a C6-C7 alkane product stream and C6-C7 olefins.

[0075] According to the present invention, in step (i), the hydrogen in the second product stream is separated by compression cooling. Preferably, the compression cooling conditions include: a temperature of -20 to 50°C and a pressure of 0.5 to 2 MPa.

[0076] According to the present invention, in step (i), the separation is not particularly limited, and any method capable of achieving gas-liquid two-phase separation may be used, such as cooling separation or membrane separation.

[0077] According to the present invention, in step (i), the liquid phase stream mainly contains C5-C7 alkanes (unreacted), C5-C7 olefins, benzene, toluene and a small amount of C8 + Hydrocarbons. The gaseous phase stream mainly contains hydrogen and a small amount of C1-C4 light hydrocarbon products. Preferably, the gaseous phase stream can be subjected to pressure swing adsorption (PSA) treatment to obtain pure hydrogen and recover it.

[0078] According to the present invention, in step (ii), there is no particular limitation on the fraction cutting, and conventional methods can be used, such as distillation. Those skilled in the art can select the cutting conditions according to the carbon number of the target product after cutting, as long as the C5 component and C6 component in the liquid phase stream can be separated. + Components can be.

[0079] According to the present invention, in step (ii), the logistics containing C5 components includes C5 alkanes (unreacted) and C5 olefins. The logistics containing C6-C7 components includes C6-C7 alkanes (unreacted), C6-C7 olefins, benzene, toluene and a small amount of C8 + Hydrocarbons.

[0080] According to the present invention, in step (iii), the alkanes and olefins in the C5 component are separated by the first alkane-olefin separation to obtain a C5 olefin product and a C5 alkane (unreacted) product stream.

[0081] In the present invention, the first alkane-olefin separation method has a relatively broad definition, as long as the alkanes and alkenes in the C5 fraction can be separated. Preferably, the first alkane-olefin separation method may include at least one of adsorption separation, solvent extraction separation, and ionic liquid separation. Those skilled in the art can select the conditions for the first alkane-olefin separation based on the target product and the specific separation method employed.

[0082] According to the present invention, the aromatic hydrocarbon separation in step (iii) is broadly defined, as long as the aromatic hydrocarbon product in the C6-C7 fraction can be separated. Preferably, the aromatic hydrocarbon separation method may include extractive separation and / or rectification. Those skilled in the art can select the conditions for aromatic hydrocarbon separation based on the target product and the specific separation method employed.

[0083] According to the present invention, in step (iii), the alkanes and olefins in the dearomatized hydrocarbon stream are separated by the second alkane-olefin separation to obtain a C6-C7 olefin product and a C6-C7 alkane (unreacted) product stream.

[0084] In the present invention, the second alkane-olefin separation method has a relatively broad definition, as long as the alkanes and olefins in the dearomatized stream can be separated. Preferably, the second alkane-olefin separation method can include at least one of adsorption separation, solvent extraction separation, and ionic liquid separation. Those skilled in the art can select the conditions for the second alkane-olefin separation based on the target product and the specific separation method employed.

[0085] According to the present invention, the method for co-producing olefins and aromatics may further comprise: recycling at least a portion of the C5 alkane product stream back to step (1) to be incorporated into the first feed stream containing C5 alkanes and participate in the first reaction;

[0086] And / or, at least a portion of the C6-C7 alkane product stream is recycled back to step (2) to be incorporated into the second feed stream containing C6-C7 alkanes and participate in the second reaction.

[0087] In the present invention, the unreacted C5 alkane product stream and / or the unreacted C6-C7 alkane product stream obtained in step (iii) are used as circulating raw materials to continue to participate in the reaction, thereby facilitating the production of more olefins and aromatics products.

[0088] According to the present invention, the method for co-producing olefins and aromatics may further comprise: before the second reaction, removing heavy components from the second feed stream containing C6-C7 alkanes. The C6-C7 alkane product stream obtained in step (iii) above may contain a small amount of heavy components C8 + Hydrocarbons, through the said heavy component removal process, the introduced heavy component C8 + Removal of hydrocarbons helps reduce catalyst carbon deposition and extend catalyst service life.

[0089] In the present invention, the treatment for removing heavy components is broadly defined and can be achieved by conventional distillation methods. Those skilled in the art can select the conditions for removing heavy components according to the target product and the specific method used.

[0090] In order to clearly describe the method for co-producing olefins and aromatics of the present invention, the following Figure 1 and Figure 2 , provides a preferred specific implementation method, including:

[0091] (1) Figure 1 As shown, a first feed stream 10 containing C5 alkanes enters a first reaction zone 1 (comprising one or two reactors connected in series), contacts a first dehydrogenation catalyst in the first reaction zone 1, and undergoes a first reaction to obtain a first product stream 12 containing hydrogen, C5 alkanes, and C5 olefins;

[0092] (2) The first product stream 12 and the second feed stream 11 containing C6-C7 alkanes are mixed to form a mixed stream 13; the mixed stream 13 enters a second reaction zone 2 (comprising 2-4 reactors connected in series), contacts with a second dehydrogenation catalyst in the second reaction zone 2 to perform a second reaction, and obtains a second product stream 14 containing hydrogen, C5-C7 alkanes, C5-C7 olefins, benzene, and toluene;

[0093] The first reaction zone 1 and the second reaction zone 2 share a catalyst regeneration unit 4;

[0094] (3) The second product stream 14 enters the compression cooling unit 5, and is compressed, cooled, and separated to obtain a hydrogen-containing gas stream 15 and a liquid stream 16; wherein the hydrogen-containing gas stream 15 is subjected to pressure swing adsorption treatment to recover pure hydrogen;

[0095] The liquid phase stream 16 enters the distillation unit 6 for fraction cutting to obtain a stream 17 containing C5 components and a stream 18 containing C6-C7 components;

[0096] The C5 component-containing stream 17 enters the C5 olefin separation unit 7 for a first alkene-olefin separation to obtain C5 olefins 19 and a C5 alkane product stream 20; wherein the C5 olefins 19 are collected as products; the C5 alkane product stream 20 is recycled and incorporated into the first C5 alkane-containing feed stream 10 to continue participating in the first reaction;

[0097] The C6-C7 component-containing stream 18 enters the aromatic separation unit 8 for aromatic separation to obtain an aromatic stream 21 and a dearomatized stream 22; wherein the aromatic stream 21 is subjected to clay adsorption or selective hydrogenation treatment to remove trace olefins contained therein, thereby obtaining high-purity benzene and toluene;

[0098] The dearomatized stream 22 enters the C6-C7 olefin separation unit 9 for second alkene separation to obtain C6-C7 olefins 23 and a C6-C7 alkane product stream 24; wherein the C6-C7 olefins 23 are collected as products; the C6-C7 alkane product stream 24 is recycled and enters the feedstock pretreatment unit 3 to be incorporated into the second feedstock stream 11 containing C6-C7 alkanes, and the second feedstock stream 11 containing C6-C7 alkanes is subjected to a heavy component removal treatment to separate the heavy component C8 + The hydrocarbon stream 25 and the second raw material stream 11 containing C6-C7 alkanes after weight removal continue to participate in the second reaction.

[0099] In the above preparation method, Figure 2As shown, a first reactor 26 is provided in the first reaction zone 1, and a second reactor 27, a third reactor 28, and a fourth reactor 29 are provided in the second reaction zone 2 (the number of reactors is for illustration only). The first reactor 26, the second reactor 27, the third reactor 28, and the fourth reactor 29 are connected in series in sequence. The first feed stream 10 containing C5 alkanes undergoes the first reaction in the first reactor 26. The resulting first product stream 12, after exiting the first reactor 26, is mixed with the second feed stream 11 containing C6-C7 alkanes to form a mixed stream 13. The mixed stream 13 enters the second reactor 27, the third reactor 28, and the fourth reactor 29 in sequence to undergo the second reaction. The resulting second product stream 14 containing hydrogen, C5-C7 alkanes, C5-C7 alkenes, benzene, and toluene enters the compression cooling unit 5 after exiting the fourth reactor 29.

[0100] The first, second, third, and fourth reactors 26, 27, 28, and 29 are each provided with a first buffer hopper 30, a second buffer hopper 31, a third buffer hopper 32, and a fourth buffer hopper 33 on their tops, and a first collector 34, a second collector 35, a third collector 36, and a fourth collector 37 on their bottoms. The catalyst regeneration unit 4 is provided with a regenerator 38, which is provided with a separation hopper 39 on its top and a regenerated catalyst collector 40 on its bottom. During the first reaction and the second reaction, the catalyst moves slowly from top to bottom under the action of gravity. The catalyst in the first reactor 26 slowly falls into the first collector 34, and is lifted to the second buffer hopper 31 at the top of the second reactor 27 by the action of the lifter (not shown in the figure), and then falls to the second reactor 27 and the second collector 35 in turn, and so on, and finally enters the fourth collector 37 at the bottom of the fourth reactor 29 (the last reactor). After that, the catalyst is lifted and moved to the separation hopper 39. After the dust in the catalyst is effectively removed, it enters the regenerator 38, is charred, oxychlorinated, dried and cooled, and is sent to the reducer for reduction. The reduced catalyst returns to the first reactor 26 from the first buffer hopper 30 again, forming a complete closed-loop cycle.

[0101] The present invention will be described in detail below by way of examples.

[0102] Dehydrogenation catalyst-1: PST-100 dehydrogenation catalyst (Sinopec Research Institute of Petroleum Processing), with a specific surface area of ​​110m 2 / g, pore volume 0.7cm 3 / g.

[0103] Dehydrogenation catalyst-2: The support is θ-alumina. Based on the total weight of the support, the active components are: 0.3wt% Pt, 0.3wt% Sn, 1wt% K, 1.2wt% Cl, 0.14wt% Eu and 0.31wt% Ce. The specific surface area is 80m 2 / g, pore volume 0.8cm 3 / g. It was prepared by the following method:

[0104] 27 g of aluminum flakes were added to 610 g of hydrochloric acid solution (the concentration of the hydrochloric acid solution was 18 wt%) to obtain an aluminum chloride solution; 850 g of aqueous ammonia (the concentration of the aqueous ammonia was 6 wt%) was added to the aluminum chloride solution, and the mixture was mixed uniformly at 60° C. The pH was adjusted to 7.5-8.5. The resulting aluminum hydroxide precipitate was filtered and washed to obtain a filter cake; 9 mL of nitric acid was added to the filter cake to obtain an alumina sol;

[0105] A hydrochloric acid solution containing SnCl2, EuCl3, and CeCl3 and 40 mL of a urea solution (containing 30 g of urea) were added to the alumina sol to adjust the Sn content, Eu content, and Ce content of the solution to 0.3% by weight of the dry alumina, 0.14% by weight of the dry alumina, and 0.31% by weight of the dry alumina. The solution was stirred for 1 h for acidification, and then 30 g of kerosene and 3 g of fatty alcohol polyoxyethylene ether were dropwise added to the acidified sol to obtain a mixed sol. The mixed sol was then dripped into an oil-ammonia column having an upper layer of an oil phase (kerosene) and a lower layer of an ammonia aqueous phase (ammonia aqueous concentration of 8 wt%) for drop spheroidization to obtain a solid product.

[0106] The solid product was solidified in an aqueous ammonia phase for 1 hour, taken out and rinsed with deionized water, and then dried at 60° C. for 6 hours and 120° C. for 10 hours. Thereafter, the solid product was first calcined in an air stream at 650° C. for 4 hours. The calcined product was treated in air with a water vapor content of 5% by volume at 650° C. for 1 hour. Thereafter, the water vapor-treated product was second-stage calcined at 1000° C. for 4 hours to obtain a spherical θ-alumina support containing Sn, Eu, and Ce (wherein the Sn content was 0.3% by weight of the support, the Eu content was 0.14% by weight of the support, and the Ce content was 0.31% by weight of the support);

[0107] The support was impregnated with an impregnation solution containing chloroplatinic acid and hydrochloric acid at 25°C for 4 hours. The solution contained 0.3 wt% Pt and 1.2 wt% Cl (Pt and Cl contents are relative to the dry weight of the alumina support, the same below) at a liquid / solid ratio of 1.6 mL / g. After impregnation, the solid was dried at 120°C for 12 hours and then calcined at 500°C for 4 hours. The resulting solid was impregnated with a KOH solution containing 1 wt% K (relative to the dry weight of the alumina support) at a liquid / solid ratio of 1.4 mL / g at 25°C for 4 hours. After impregnation, the solid was dried at 120°C for 12 hours and then oxychlorinated with air containing water and HCl (with a H2O / HCl molar ratio of 20:1) at 600°C for 4 hours. The product was then reduced with hydrogen for 2 hours to obtain dehydrogenation catalyst-2.

[0108] The specific surface area and pore volume of the catalyst were measured using a BET analyzer (manufacturer: Micromertics, model 3Flex).

[0109] Raw material 1: pentane oil, PONA analysis data see Table 1.

[0110] Raw material 2: C6 raffinate oil, PONA analysis data see Table 2.

[0111] Table 1

[0112] project P N A total C4 alkanes 0.21 0.00 0.00 0.21 C5 alkanes 89.10 8.94 0.00 98.04 C6 alkanes 1.51 0.15 0.00 1.66 C7 alkanes 0.00 0.00 0.00 0.00 total 90.82 9.09 0.00 99.91

[0113] Table 2

[0114] project P N A total C4 alkanes 0.00 0.00 0.00 0.00 C5 alkanes 0.10 0.00 0.00 0.10 C6 alkanes 77.89 7.95 0.06 85.90 C7 alkanes 13.50 0.44 0.00 13.94 total 91.49 8.39 0.06 99.94

[0115] Example 1

[0116] use Figure 1 The process shown and Figure 2 The illustrated composition of the first reaction zone, the second reaction zone and the catalyst regeneration unit allows for the co-production of olefins and aromatics.

[0117] (1) A first feed stream 10 (feedstock 1) containing C5 alkanes is introduced into a first reaction zone 1 (using one reactor), and is contacted with a dehydrogenation catalyst-2 in the first reaction zone 1 to carry out a first reaction (reaction temperature is 555°C, pressure is 0.1 MPa; hydrogen-to-hydrocarbon molar ratio is 1:1; mass space velocity of the first feed stream 10 is 2 h -1 ), to obtain a first product stream 12 containing hydrogen, C5 alkanes and C5 olefins;

[0118] (2) The first product stream 12 obtained in step (1) and the second feed stream 11 (feedstock 2) containing C6-C7 alkanes are mixed to form a mixed stream 13 (the weight ratio of feedstock 1:feedstock 2 is 1:4); the mixed stream 13 enters the second reaction zone 2 (using three reactors in series), and contacts with the dehydrogenation catalyst-2 in the second reaction zone 2 to carry out the second reaction (reaction temperature is 525°C, pressure is 0.1 MPa; hydrogen-to-hydrocarbon molar ratio is 1:1; the total mass space velocity of the first product stream 12 and the second feed stream 11 is 2h -1 ) to obtain a second product stream 14 containing hydrogen, C5-C7 alkanes, C5-C7 olefins, benzene and toluene;

[0119] (3) The second product stream 14 enters the compression cooling unit 5, where it is compressed, cooled (at a temperature of -10°C and a pressure of 1.5 MPa) and separated to obtain a hydrogen-containing gaseous stream 15 and a liquid stream 16. The hydrogen-containing gaseous stream 15 is subjected to pressure swing adsorption treatment to recover pure hydrogen.

[0120] The liquid phase stream 16 enters the distillation unit 6 for fraction cutting to obtain a stream 17 containing C5 components and a stream 18 containing C6-C7 components;

[0121] The C5 component-containing stream 17 enters the C5 olefin separation unit 7 for a first alkene-alkene separation to obtain C5 olefins 19 and a C5 alkane product stream 20; the C5 alkane product stream 20 is recycled and incorporated into the feedstock 1 and continues to participate in the first reaction; the C5 olefins 19 are collected as products;

[0122] The C6-C7 component stream 18 enters the aromatic separation unit 8 for aromatic separation to obtain an aromatic stream 21 and a dearomatized stream 22. The aromatic stream 21 is subjected to white earth adsorption treatment to obtain high-purity benzene and toluene, which are collected as products.

[0123] The dearomatized stream 22 enters the C6-C7 olefin separation unit 9 for the second alkene separation to obtain C6-C7 olefins 23 and a C6-C7 alkane product stream 24; wherein the C6-C7 alkane product stream 24 enters the feedstock pretreatment unit 3 and is incorporated into the feedstock 2, and the feedstock 2 is subjected to a heavy component removal treatment to separate the heavy component C8 + The hydrocarbon stream 25 and the deweighted feedstock 2 enter the second reaction zone 2 to continue the second reaction. The C6-C7 olefins 23 are collected as products.

[0124] In the above preparation process, the first reaction zone 1 and the second reaction zone 2 share a catalyst regeneration unit 4. In the first reaction zone 1, the catalyst in the first reactor 26 slowly falls into the first collector 34 at the bottom, and is lifted to the second buffer hopper 31 at the top of the second reactor 27 in the second reaction zone 2 by the action of the lifter, and then falls to the second reactor 27 and the second collector 35 in sequence, and so on, and finally enters the fourth collector 37 at the bottom of the fourth reactor 29. After that, the catalyst is lifted into the catalyst regeneration unit 4 and enters the separation hopper 39 at the top of the regenerator 38. After the dust in the catalyst is effectively removed, it enters the regenerator 38, is charred, oxychlorinated, dried and cooled, and is sent to the reducer for reduction. The reduced catalyst returns to the first reactor 26 again through the first buffer hopper 30, forming a complete closed-loop cycle.

[0125] In this embodiment, the yields of product olefins and aromatics are shown in Table 3.

[0126] Example 2

[0127] The method of Example 1 was followed, except that the temperature of the first reaction was 560° C. and the temperature of the second reaction was 520° C. The other steps and conditions were the same as those of Example 1.

[0128] In this embodiment, the yields of product olefins and aromatics are shown in Table 3.

[0129] Example 3

[0130] The method of Example 1 was followed, except that the temperature of the first reaction was 550° C. and the temperature of the second reaction was 530° C. The other steps and conditions were the same as those of Example 1.

[0131] In this embodiment, the yields of product olefins and aromatics are shown in Table 3.

[0132] Example 4

[0133] The method of Example 1 was followed, except that the temperature of the first reaction was 545° C. and the temperature of the second reaction was 535° C. The other steps and conditions were the same as those of Example 1.

[0134] In this embodiment, the yields of product olefins and aromatics are shown in Table 3.

[0135] Example 5

[0136] The method of Example 1 was followed, except that the temperature of the first reaction was 565° C. and the temperature of the second reaction was 515° C. The other steps and conditions were the same as those of Example 1.

[0137] In this embodiment, the yields of product olefins and aromatics are shown in Table 3.

[0138] Example 6

[0139] The method of Example 5 was followed, except that the weight ratio of raw material 1:raw material 2 was 1:10, and the other steps and conditions were the same as those of Example 5.

[0140] In this embodiment, the yields of product olefins and aromatics are shown in Table 3.

[0141] Example 7

[0142] The method of Example 5 was followed, with the only difference being that the dehydrogenation catalyst-2 was replaced with an equal weight of the dehydrogenation catalyst-1. The other steps and conditions were the same as those of Example 5.

[0143] In this embodiment, the yields of product olefins and aromatics are shown in Table 3.

[0144] Comparative Example 1

[0145] The method of Example 5 is followed, except that step (1) and step (2) are replaced by "raw material 1 and raw material 2 are mixed in a weight ratio of 1:4 to obtain a mixture, and the mixture is sequentially passed through a first reaction zone 1 (for a first reaction) and a second reaction zone 2 (for a second reaction), wherein the conditions of the first reaction and the second reaction are the same as those of Example 5, to obtain a reaction product", and the reaction product obtained after the second reaction is subjected to step (3) of Example 5. The other steps and conditions are the same as those of Example 5.

[0146] In this comparative example, the yields of product olefins and aromatics are shown in Table 3.

[0147] Comparative Example 2

[0148] (1) The raw material 1 is introduced into the first reaction zone 1 (using one reactor), and is contacted with the dehydrogenation catalyst-2 in the first reaction zone 1 to carry out the first reaction (reaction temperature is 565°C, pressure is 0.1 MPa; hydrogen-to-hydrocarbon molar ratio is 1:1; mass space velocity of the raw material 1 is 2h -1 ), to obtain a first product stream;

[0149] The first product stream is compressed, cooled (temperature of -10°C, pressure of 1.5 MPa), and separated to obtain a gaseous stream and a liquid stream; the gaseous stream is subjected to pressure swing adsorption treatment to recover pure hydrogen; the liquid stream is subjected to a first alkane-olefin separation to obtain C5 olefins (product) and a C5 alkane stream; the C5 alkane stream is recycled and incorporated into feedstock 1 to continue participating in the first reaction;

[0150] (2) Raw material 2 (the weight ratio of raw material 1 to raw material 2 is 1:4) is introduced into the second reaction zone 2 (using three reactors in series), and is contacted with dehydrogenation catalyst-2 in the second reaction zone 2 to carry out the second reaction (reaction temperature is 515°C, pressure is 0.1 MPa; hydrogen-hydrocarbon molar ratio is 1:1; mass space velocity of raw material 2 is 2h -1), to obtain a second product stream;

[0151] The second product stream is compressed and cooled (temperature is -10°C, pressure is 1.5 MPa), and separated to obtain a gaseous stream and a liquid stream; wherein the gaseous stream is subjected to pressure swing adsorption treatment to recover pure hydrogen;

[0152] The liquid phase stream is subjected to aromatic separation to obtain an aromatic stream and a dearomatized stream; wherein the aromatic stream is subjected to white earth adsorption treatment to obtain high-purity benzene and toluene (products);

[0153] The dearomatized stream is subjected to a second alkene separation to obtain C6-C7 olefins (products) and C6-C7 alkane stream; wherein the C6-C7 alkane stream is recycled and incorporated into the feedstock 2, and the feedstock 2 is subjected to a heavy component removal treatment to separate the heavy component C8 + The hydrocarbon flow and the deweighted raw material 2 enter the second reaction zone 2 to continue the second reaction.

[0154] In this comparative example, the yields of product olefins and aromatics are shown in Table 3.

[0155] Table 3

[0156]

[0157] As can be seen from Table 3, the method provided by the present invention can utilize C5-C7 alkanes to co-produce olefins and aromatics, achieving an olefin yield higher than 20%, while an aromatics yield higher than 5%, and a total yield of olefins and aromatics higher than 38%. Among them, Examples 1-3 show particularly outstanding effect advantages, achieving an olefin yield higher than 24%, while an aromatics yield higher than 21%, and a total yield of olefins and aromatics higher than 46%. Comparing the effects of Examples 1-3 and 4-5, it can be seen that by controlling the temperature of the first reaction to be 10-40°C higher than the temperature of the second reaction, higher olefin and aromatics yields can be achieved. Comparing the effects of Example 5 and Example 6, it can be seen that the weight ratio of raw material 1 (mainly containing C5 alkanes) to raw material 2 (mainly containing C6-C7 alkanes) is reduced to 1:10, so that the yields of C5 olefins and benzene decrease, which may be related to the decrease in the ratio of C5 olefins, affecting the metathesis reaction with C7 olefins, thereby causing a decrease in benzene yield. Comparing the effects of Example 5 and Example 7, it can be seen that compared with Dehydrogenation Catalyst-1, Dehydrogenation Catalyst-2 is more conducive to improving the yield of aromatics.

[0158] In particular, in Comparative Example 1, where Raw Materials 1 and 2 were mixed and subsequently subjected to the first and second reactions, the total yield of olefins and aromatics decreased. This was due to the different dehydrogenation difficulties of C5 alkanes and C6-C7 alkanes. The combined reaction failed to match the reaction conditions for each, leading to increased side reactions and a reduction in the total yield of olefins and aromatics. In Comparative Example 2, the C5 alkane was subjected only to the first reaction, resulting in a decrease in conversion. Furthermore, since Comparative Example 2 reacted the C5 alkane and C6-C7 alkanes independently, metathesis between the C5 and C7 alkanes could not occur, resulting in a decrease in the total yield of olefins and aromatics.

[0159] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A method for co-producing olefins and aromatics, characterized in that: include: (1) subjecting a first feed stream containing C5 alkanes to a first reaction in the presence of a first dehydrogenation catalyst to obtain a first product stream containing hydrogen, C5 alkanes and C5 olefins; (2) in the presence of a second dehydrogenation catalyst, subjecting the first product stream and a second feed stream containing C6-C7 alkanes to a second reaction to obtain a second product stream containing hydrogen, C5-C7 alkanes, C5-C7 olefins, benzene and toluene; (3) subjecting the second product stream to product separation treatment to obtain C5-C7 olefins, benzene and toluene; Wherein, the temperature of the second reaction is 10-60°C lower than the temperature of the first reaction.

2. The method according to claim 1, wherein: The content of C5 alkanes in the first C5 alkane-containing feed stream is ≥ 85 wt%, preferably 92-99 wt%; And / or, the total content of C6 alkanes and C7 alkanes in the second raw material stream containing C6-C7 alkanes is ≥90wt%, preferably 95-99wt%.

3. The method according to claim 1 or 2, wherein: The conditions of the first reaction include: a temperature of 480-580°C, preferably 520-580°C; a pressure of 0.01-1MPa; a hydrogen-to-hydrocarbon molar ratio of (0.1-10):1; a mass space velocity of the first raw material stream containing C5 alkanes of 1-6h -1 ; And / or, the conditions of the second reaction include: temperature of 440-540°C, preferably 500-540°C; pressure of 0.01-1MPa; hydrogen-to-hydrocarbon molar ratio of (0.1-10):1; the total mass space velocity of the first product stream and the second feed stream containing C6-C7 alkanes is 1-6h -1 .

4. The method according to any one of claims 1 to 3, wherein: The weight ratio of the first raw material stream containing C5 alkanes to the second raw material stream containing C6-C7 alkanes is 1:(2-8), preferably 1:(3-6).

5. The method according to any one of claims 1 to 4, wherein: The first dehydrogenation catalyst and the second dehydrogenation catalyst each independently include a carrier and an active component; Wherein, based on the total weight of the carrier, the active components include: 0.1-2wt% of Group VIII metal, 0.1-2wt% of Group IIIA and / or Group IVA metal, 0.5-5wt% of Group IA metal, 0.3-10wt% of halogen, 0.1-1wt% of Eu and 0.1-1wt% of Ce; The carrier is selected from at least one of aluminum oxide, silicon oxide, zirconium oxide and titanium oxide.

6. The method according to claim 5, wherein: The Group VIII metal is selected from Pt and / or Pd; and / or, the IIIA group and / or IVA group metal is selected from at least one of Ge, Sn, Pb, Ga, In and Tl; And / or, the Group IA metal is selected from Na and / or K.

7. The method according to any one of claims 5 to 6, wherein: The specific surface area of ​​the first dehydrogenation catalyst and the second dehydrogenation catalyst is 50-130m 2 / g, pore volume is 0.5-1cm 3 / g; Preferably, the first catalyst and the second catalyst are the same.

8. The method according to any one of claims 1 to 7, wherein: The product separation process comprises: (i) compressing, cooling and separating the second product stream in sequence to obtain a liquid stream and a hydrogen-containing gas stream; (ii) fractionating the liquid phase stream to obtain a stream containing C5 components and a stream containing C6-C7 components; (iii) subjecting the C5 component-containing stream to a first alkane-olefin separation to obtain a C5 alkane product stream and C5 olefins; The C6-C7 component-containing stream is subjected to aromatic separation to obtain a dearomatized stream, benzene and toluene; then the dearomatized stream is subjected to a second alkane-olefin separation to obtain a C6-C7 alkane product stream and C6-C7 olefins.

9. The method according to claim 8, wherein: The compression cooling conditions include: temperature of -20 to 50°C and pressure of 0.5-2MPa; and / or, the first alkane-olefin separation and the second alkane-olefin separation method include at least one of adsorption separation, solvent extraction separation and ionic liquid separation; And / or, the method for separating aromatic hydrocarbons comprises solvent extraction separation and / or distillation.

10. The method according to claim 8 or 9, wherein: The method further comprises: recycling at least a portion of the C5 alkane product stream back to step (1) to be incorporated into the first feed stream containing C5 alkane and participate in the first reaction; and / or, recycling at least a portion of the C6-C7 alkane product stream back to step (2) to be incorporated into the second feed stream containing C6-C7 alkanes and participate in the second reaction; Preferably, before the second reaction, the second feedstock stream containing C6-C7 alkanes is treated to remove heavy components.

Images