Method for preparing alkylate oil

Abstract

The invention relates to a method for preparing alkylated oil. The method comprises the following steps: enabling a mixed raw material containing isoparaffin and olefin to be in contact with a catalyst in a weak acid environment in an alkylation reactor to carry out alkylation reaction, the alkylation reactor is a tubular reactor. Wherein the weak acid environment can be solid acid or liquid acid. The tubular reactor is adopted, side reactions are reduced by accurately controlling the inlet temperature of the reactor and taking effective heat removal measures of a bed layer, and therefore it is guaranteed that the solid acid catalyst can operate for a long period, and the regeneration frequency is reduced; or when a liquid weak acid environment is used, the acid consumption of liquid acid can be reduced, the discharge of waste acid is reduced, and even zero discharge of waste acid is realized. The device has the effects that a compressor is not arranged, and the equipment investment cost and energy consumption are reduced. Meanwhile, heat released by alkylation reaction can be effectively recovered, so that the steam consumption of an alkylation process is greatly reduced, and the production cost of alkylated oil is greatly reduced.

Description

Technical Field

[0001] The present disclosure belongs to the field of alkylated oil, and particularly relates to a method for preparing alkylated oil. Background Art

[0002] Under the catalytic action of an acidic catalyst, alkylated oil generated by the conversion of olefins and isobutane under certain conditions of temperature, pressure, and alkene-to-alkane ratio has a high octane number / cetane number and is an ideal gasoline / diesel blending component. In existing alkylation processes, the main typical processes include liquid acid alkylation process and solid acid alkylation process.

[0003] In the liquid acid alkylation process, since the alkylation reaction is an exothermic reaction, in order to control the low-temperature reaction temperature of liquid acid alkylation, it is usually necessary to use a refrigeration system to cool the coolant / reactant material, and control the reaction temperature by circulating the cooled coolant / reactant material. Taking the low-temperature sulfuric acid alkylation method as an example, in the alkylation reactor, the reaction raw material isobutane in the reaction system is vaporized by pumping negative pressure through a compressor. The vaporization of isobutane absorbs the heat released by the reaction. The vaporized isobutane is further cooled and liquefied through a compressor, heat exchanger, and refrigeration system and then recycled back to the reactor. On the one hand, this method requires the compressor to boost the pressure of the reaction raw material isobutane in the reaction system, and requires a refrigeration system and heat exchanger for cooling and liquefaction, which has problems such as large equipment investment and high energy consumption. On the other hand, a large amount of heat released by the alkylation reaction cannot be effectively utilized, resulting in energy waste.

[0004] US5443799 and US3759318 disclose that they mainly focus on how to use rapid shearing operations to quickly form a uniform emulsion phase of acid and hydrocarbon. For example: the reactor is divided into a premixing zone and a reaction zone. In the premixing zone of the reactor, isobutane is ejected through an ejector and mixed with sulfuric acid to form an emulsion, and the olefin reacts with the emulsion from the premixing zone in a countercurrent manner in the reaction zone. The volume of the reaction zone is significantly larger than that of the premixing zone. After the premixed mixture of isobutane and sulfuric acid enters the reaction zone, the volume suddenly increases, and the adiabatic expansion absorbs the heat released by the alkylation reaction. There are still problems of high energy consumption and inability to recover the heat released by the reaction.

[0005] CN101104570A and CN103357369A disclose a static mixing system formed by designing the internal structure of the reactor. Under the cutting and dispersing action of structured packing, the acid and hydrocarbon are fully mixed, and the reaction heat is removed by a cooling medium. This method requires the introduction of a new cooling medium, and there is a risk that the reaction effect will be seriously affected due to the leakage of the cooling medium.

[0006] Secondly, while producing alkylated oil, the liquid acid alkylation process is accompanied by a large amount of low-concentration waste acid as a by-product. The low-concentration waste acid produced as a by-product needs to be further treated in order to recycle the liquid acid catalyst. In the low-temperature sulfuric acid method, the liquid acid catalyst uses concentrated sulfuric acid with a concentration of 98 wt%. For every 1 ton of isooctane produced, 50 kg of waste sulfuric acid with a concentration of about 90% is generated. In addition to sulfuric acid, its composition also contains about 7% of organic matter and about 3% of moisture. Since the higher the concentration of the liquid acid catalyst, the more waste sulfuric acid that needs to be further treated as a by-product. Waste sulfuric acid is a viscous colloidal liquid with a dark red color, unstable properties, emitting a special odor, and is difficult to recycle and treat, causing serious environmental pollution.

[0007] In addition, compared with the liquid acid alkylation process, the solid acid alkylation process has advantages such as being cleaner, safer and more environmentally friendly, and less hazardous waste treatment. However, since the by-products generated during the alkylation reaction will adhere to the surface of the catalyst, gradually covering the acidic centers. When the number of acidic centers decreases to a certain extent, the activity of the catalyst will rapidly decline. In order to maintain a certain reaction activity, frequent regeneration operations are required. Therefore, solid acid catalysts have problems such as being easily deactivated and having a relatively short single-pass life of the catalyst. At present, some solid acid alkylation processes have been industrially applied.

[0008] CN115537229A discloses a method and reaction device for extending the operation cycle of solid acid alkylation reaction. By using multiple reactors and separators in series, and adding reactions to multiple reactors sequentially, the operation cycle is increased by 20 - 50% compared to a single reactor device under the same weight hourly space velocity. However, this method has problems such as high equipment investment and complex operation processes.

[0009] Therefore, the liquid acid alkylation process still has disadvantages such as being unable to effectively utilize the reaction heat in order to control the alkylation reaction temperature, having high energy consumption, and high waste acid treatment costs generated by the liquid acid catalyst. Secondly, how to extend the activity cycle and lifespan of solid acid catalysts is an urgent problem to be solved in the current solid acid process. Summary of the Invention

[0010] The object of the present disclosure is to provide a method for preparing alkylated oil. The method provided by the present invention can improve the lifespan and activity of solid acid catalysts, while reducing the acid consumption of liquid acid catalysts, reducing waste acid emissions, and effectively recovering the heat released during the alkylation reaction, reducing the energy consumption of the alkylation process, and reducing production costs.

[0011] To achieve the above object, the present invention provides a method for preparing alkylated oil, including: contacting a mixed raw material containing isoparaffin and olefin with a catalyst in a weak acidic environment in an alkylation reactor to carry out an alkylation reaction; wherein, the alkylation reactor is a shell-and-tube reactor.

[0012] Optionally, the catalyst for the weakly acidic environment includes a solid acid catalyst or a liquid acid catalyst; the solid acid catalyst includes a weak acid or an acidic molecular sieve, etc., and the liquid acid catalyst includes a low-concentration strong acid catalyst or a very weak acid; the mass concentration of the liquid acid catalyst in the alkylation reaction system is 0.01%-10%; wherein, the reaction temperature of the alkylation reaction is 40-200 °C, and the reaction pressure is 0.5-8.0 Mpa.

[0013] Optionally, the reaction heat released by the alkylation reaction is removed by the heat extraction medium in the jacket of the tubular reactor, and the heat extraction medium includes circulating water and / or jacket water or generates steam; preferably, the inlet temperature of the mixed raw material of the tubular reactor is 30-190 °C, and the inlet temperature of the heat extraction medium is 35-180 °C.

[0014] Optionally, the carbon number of the isoparaffin in the mixed raw material is 4-8, preferably isobutane; the carbon number of the olefin in the mixed raw material is 3-8, preferably at least one of propylene, n-butene, 2-butene, pentene, hexene, heptene and octene.

[0015] Optionally, the mixed raw material is selected from at least one of the carbon four raw materials after etherification, the carbon five raw materials from pyrolysis and the carbon six raw materials after extraction of aromatics; preferably the carbon four raw materials after etherification.

[0016] Optionally, the molar ratio of isoparaffin to olefin in the mixed raw material is 5-20, preferably 7-12.

[0017] Optionally, the liquid acid catalyst is selected from at least one of sulfuric acid, hydrofluoric acid, dodecylbenzenesulfonic acid, preferably dodecylbenzenesulfonic acid.

[0018] Optionally, the solid acid catalyst is selected from at least one of acidic cation resin, solid phosphoric acid, acidic molecular sieve, preferably acidic molecular sieve.

[0019] Optionally, the conditions of the alkylation reaction further include that the liquid hourly space velocity of the olefin relative to the solid acid catalyst in the mixed raw material is 0.5-2.0 h -1 , preferably 1.0-2.0 h -1 .

[0020] Optionally, the product of the alkylation reactor is directly sent to a separation device through pressure for separation to obtain alkylated oil, unreacted isoparaffin, and optionally recycled catalyst.

[0021] Optionally, heat exchange tubes are arranged in the tubular reactor, and the heat exchange tubes are filled with the solid acid catalyst that is beneficial to the mixing of the reaction medium or the filler that is easy to fully mix the hydrocarbon and the liquid acid catalyst.

[0022] Through the above technical solutions, compared with the prior art, the present disclosure has the following specific advantages:

[0023] The present disclosure uses a shell-and-tube reactor. By precisely controlling the reactor inlet temperature and effective heat removal measures in the bed layer, the generation of side reactions is reduced, thereby ensuring the long-term operation of the solid acid catalyst and reducing the number of regenerations; or when using a weak liquid acid environment, the liquid acid consumption can be reduced, the waste acid discharge can be reduced, and even zero waste acid discharge can be achieved.

[0024] The present disclosure can eliminate the need for a compressor, reducing equipment investment costs and energy consumption. At the same time, by effectively recovering the heat released during the alkylation reaction, the steam consumption of the alkylation process can be significantly reduced, greatly reducing the production cost of alkylated oil.

[0025] Other features and advantages of the present invention will be described in detail in the subsequent specific implementation section. Brief Description of the Drawings

[0026] The drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the following specific implementation, they are used to explain the present invention, but do not constitute a limitation to the present invention. In the drawings:

[0027] Figure 1 is the process flow diagram provided for Embodiment 1 of the present invention.

[0028] Figure 2 is the process flow diagram provided for Embodiment 5 of the present invention.

[0029] Description of the Reference Numerals in the Drawings

[0030] Figure 1 : 1, alkylation reactor; 2, acid-hydrocarbon separation coalescer; 3, product separation column; 4, butane separation column; 5, heat extraction medium inlet; 6, heat extraction medium outlet.

[0031] S1, C4 hydrocarbons after etherification; S2, alkylation reaction product; S3, reaction product after removing the acid catalyst; S4, C4 alkanes; S5, high-concentration n-butane; S6, recycled isobutane; S7, high-concentration isobutane; S8, recycled acid catalyst; S9, alkylated oil; S10, fresh acid catalyst.

[0032] Figure 2 : 1, alkylation reactor; 3, product separation column; 4, butane separation column; 5, heat extraction medium inlet; 6, heat extraction medium outlet.

[0033] S1, C4 hydrocarbons after etherification; S2, alkylation reaction product; S4, C4 alkanes; S5, high-concentration n-butane; S6, recycled isobutane; S7, high-concentration isobutane; S9, alkylated oil. Detailed Description of the Invention

[0034] The following will describe in detail the specific embodiments of the present disclosure with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only for the purpose of illustrating and explaining the present disclosure, and are not intended to limit the present disclosure.

[0035] The present disclosure provides a method for preparing alkylated oil, including: contacting a mixed raw material containing isoparaffin and olefin with a catalyst in a weak acidic environment in an alkylation reactor, and the alkylation reactor is a shell-and-tube reactor.

[0036] In the present disclosure, the catalyst in the weak acidic environment can be a catalyst that provides a weak acidic catalytic reaction environment in the alkylation reaction. In a specific embodiment, the catalyst in the weak acidic environment can be a solid acid catalyst or a liquid acid catalyst; the solid acid catalyst includes weak acids or acidic zeolites, etc., and the liquid acid catalyst includes low-concentration strong acid catalysts or very weak acid catalysts. The mass concentration of the liquid acid catalyst in the alkylation reaction system is 0.01% to 10%, preferably 0.1% to 2%. Specifically, the mass concentration of the liquid acid catalyst in the alkylation reaction system can be 0.01%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5%, 5.0%, 5.5%, 6.0%, 6.5%, 7.0%, 7.5%, 8.0%, 8.5%, 9.0%, 9.5%, 10.0%, etc., or any value between the above adjacent values.

[0037] In a specific embodiment, the liquid acid catalyst is selected from one or more of sulfuric acid, hydrofluoric acid or dodecylbenzenesulfonic acid, preferably dodecylbenzenesulfonic acid. In the above embodiment, the liquid acid catalyst can use a strong acid catalyst sulfuric acid or hydrofluoric acid with a very low concentration, or a weak acid catalyst dodecylbenzenesulfonic acid. Compared with the prior art, by reducing the mass concentration of the acidic catalyst in the reaction system, this method can reduce the side reactions caused by the contact between the acidic catalyst and olefins, greatly reduce the acid consumption, reduce the waste acid discharge, and even achieve zero waste acid discharge, and reduce the catalyst treatment cost.

[0038] In a specific embodiment, the solid acid catalyst is selected from one or more of acidic cation resins, solid phosphoric acid or acidic supported zeolites, preferably acidic supported zeolites. In the above embodiment, the solid acid catalyst can use a weakly acidic cation resin, such as sulfonic acid resin or waste sulfonic acid resin, or an acidic supported zeolite, etc.

[0039] In a specific embodiment, the reaction temperature of the alkylation reaction is 40 to 200 °C, preferably 90 to 150 °C. Specifically, the reaction temperature of the alkylation reaction can be 40 °C, 50 °C, 60 °C, 70 °C, 80 °C, 90 °C, 100 °C, 110 °C, 120 °C, 130 °C, 140 °C, 150 °C, 160 °C, 170 °C, 180 °C, 190 °C, 200 °C, etc., or any value between the adjacent values above.

[0040] In a specific embodiment, the reaction pressure of the alkylation reaction is 0.5 to 8.0 Mpa, preferably 1.0 to 4.0 Mpa. Specifically, the reaction pressure can be 0.5 MPa, 1.0 MPa, 1.5 MPa, 2.0 MPa, 2.5 MPa, 3.0 MPa, 3.5 MPa, 4.0 MPa, 4.5 MPa, 5.0 MPa, 5.5 MPa, 6.0 MPa, 6.5 MPa, 7.0 MPa, 7.5 MPa, 8.0 MPa, etc., or any value between the adjacent values above.

[0041] In the above embodiment, the present disclosure adopts a shell-and-tube reactor, takes advantage of the large heat transfer area of the shell-and-tube reactor, and reduces the generation of side reactions through precise control of the reactor inlet temperature and effective heat removal measures in the bed layer, thereby ensuring that the solid acid catalyst can operate for a long period and greatly reducing the number of regeneration operations of the solid acid catalyst. Or when using a low-concentration liquid acid catalyst, it can reduce the acid consumption of the liquid acid catalyst, reduce the waste acid discharge, and even achieve zero waste acid discharge.

[0042] Secondly, by increasing the reaction temperature and the reaction pressure, the isoparaffins and olefins in the mixed raw materials are in a liquid phase, eliminating the need for equipment such as compressors, reducing equipment investment costs and power consumption. At the same time, increasing the alkylation reaction temperature and combining it with a shell-and-tube reactor can effectively recover about 700 kJ / kg of the heat released by the alkylation reaction. The recovered reaction heat can be used for steam production, etc., significantly reducing the production energy consumption of the alkylation process, improving the energy utilization efficiency of the alkylation process, and greatly reducing production costs.

[0043] In a specific embodiment, the reaction heat released by the alkylation reaction is removed by the heat extraction medium in the jacket of the tubular reactor. The heat extraction medium includes circulating water and / or jacket water or generates steam. Preferably, the inlet temperature of the mixed raw materials of the tubular reactor is 30-190°C, and the inlet temperature of the heat extraction medium is 35-180°C. Specifically, the inlet temperature of the mixed raw materials of the tubular reactor can be 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, etc., or any value between the adjacent values above. The inlet temperature of the heat extraction medium can be 35°C, 45°C, 55°C, 65°C, 75°C, 85°C, 95°C, 105°C, 115°C, 125°C, 135°C, 145°C, 155°C, 165°C, 175°C, 180°C, etc., or any value between the adjacent values above.

[0044] In the above embodiment, by controlling the inlet temperature of the mixed raw materials or the inlet temperature of the heat extraction medium, the heat released by the reaction is effectively transferred, and effective heat removal of the fixed bed layer is achieved, so as to more accurately control the temperature of the fixed bed layer, reduce the generation of side reactions, ensure the long-term operation of the solid acid catalyst, and greatly reduce the number of regeneration operations of the solid acid catalyst. The heat extraction medium can be circulating water or jacket water. The heat released by the reaction is taken away by the circulating water for recovery, and the recovered reaction heat can be used for steam production, etc., to effectively recover the heat released by the alkylation reaction, greatly reduce the energy consumption of the alkylation process production, and improve the energy utilization efficiency of the alkylation process.

[0045] In a further embodiment, the mixed raw materials adopt an upward inlet and downward outlet feeding method, and the heat extraction medium adopts a countercurrent contact method of downward inlet and upward outlet for heat extraction. By adopting the countercurrent contact method, the heat exchange efficiency can be further improved, and the heat released by the alkylation reaction can be better taken away by heat extraction.

[0046] In a specific embodiment, the number of carbon atoms of the isoparaffin in the mixed raw materials is 4-8, preferably isobutane. The number of carbon atoms of the olefin in the mixed raw materials is 3-8, preferably at least one of propylene, n-butene, 2-butene, pentene, hexene, heptene and octene.

[0047] In a specific embodiment, the mixed raw materials are selected from at least one of the carbon four raw materials after etherification, the carbon five raw materials after cracking and the carbon six raw materials after extraction of aromatics, preferably the carbon four raw materials after etherification. Specifically, the carbon four raw materials after etherification include isobutane, n-butene, cis-2-butene, trans-2-butene and butadiene.

[0048] In a specific embodiment, the molar ratio of isoparaffin to olefin in the mixed raw material is 5 to 20, preferably 7 to 12. Specifically, the molar ratio of isoparaffin to olefin in the mixed raw material can be 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, etc., or any value between adjacent values above.

[0049] In a specific embodiment, the conditions of the alkylation reaction further include: the liquid hourly space velocity of olefin in the mixed raw material relative to the solid acid catalyst is 0.5 to 2.0 h -1 , preferably 1.0 to 2.0 h -1 . Specifically, the liquid hourly space velocity of olefin in the mixed raw material relative to the solid acid catalyst can be 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, etc., or any value between adjacent values above. In the above embodiment, the occurrence of side reactions can be better avoided, the generation of by-products during the reaction can be reduced, the long-term operation of the solid acid catalyst can be ensured, and the number of regeneration operations of the solid acid catalyst can be reduced.

[0050] In a specific embodiment, the product of the alkylation reactor is directly sent to a separation device through pressure for separation to obtain alkylated oil, unreacted isoparaffin, and optional recycled catalyst. In the above embodiment, the alkylation reaction product in the alkylation reactor is sent to the separation device by self-pressure, without being sent by compressor boosting, reducing the equipment investment cost and energy consumption. After separation from the separation device, alkylated oil, unreacted isoparaffin, and optional recycled catalyst are obtained. The optional recycled catalyst is a liquid acid catalyst obtained by acid-hydrocarbon separation when using a liquid acid catalyst. By separating and recovering unreacted isoparaffin and liquid acid catalyst, the recycling of reaction materials and catalyst is realized, the product yield is improved, and the production cost is reduced.

[0051] In a further embodiment, the unreacted isoparaffin is returned to the alkylation reactor; the optional recycled catalyst is returned to the alkylation reactor for recycling. In the above embodiment, by circulating the unreacted isoparaffin back to the reactor inlet, the molar ratio of isoparaffin to olefin in the mixed raw material is controlled.

[0052] In a further embodiment, optional fresh acid catalyst is supplemented at the inlet of the alkyl reactor. In the above embodiment, by supplementing optional fresh acid, the liquid acid catalyst in the alkylation reactor is controlled at a certain mass concentration to ensure the occurrence of the alkylation reaction, while reducing the waste acid discharge during the alkylation reaction, greatly reducing the waste acid treatment cost of reaction by-products, and significantly reducing the production cost.

[0053] In a specific embodiment, heat exchange tubes are arranged in the shell-and-tube reactor, and a solid acid catalyst that facilitates the mixing of reaction media or a filler that easily enables the full mixing of hydrocarbons and liquid acid catalyst is filled in the heat exchange tubes. In the above embodiment, when using a solid acid catalyst, the heat exchange tubes of the shell-and-tube reactor are filled with the solid acid catalyst, and this solid catalyst is conducive to the mixing of reaction media and promotes mass transfer and heat transfer between reaction media. When using a liquid acid catalyst, the heat exchange tubes of the shell-and-tube reactor are filled with a filler, and this filler can promote the full mixing of hydrocarbons and liquid acid catalyst, make the mixing of acid catalyst and hydrocarbons more uniform, and improve the reaction mass transfer and heat transfer efficiency. For example, the filler can be a fiber membrane filler.

[0054] Furthermore, the separation device may include a product separation tower, a butane separation tower, a deweighting tower, and a catalyst separator. Each separation device can be of a conventional type in the art, such as selected from a flash evaporator, a distillation column, a gas-liquid separator, a coalescer, etc.

[0055] In a preferred specific embodiment of the present disclosure, a liquid acid catalyst is used, such as Figure 1 As shown, the separation device includes a product separation tower 3, a butane separation tower 4, and an acid-hydrocarbon separation coalescer 2 to separate the mixed materials generated by the alkylation reaction.

[0056] In the present disclosure, isoparaffin and olefin react under the action of a liquid acid catalyst in a reactor to generate alkylated oil. The alkylation reaction is an exothermic reaction, and the heat released by the reaction is taken away by the shell-and-tube reactor using a heat extraction medium to circulate and extract heat. The alkylation reaction temperature can be controlled at 40-200°C by controlling the circulation amount of the heat extraction medium, the temperature of the heat extraction medium, the inlet temperature of the tube reactor, etc.

[0057] Specifically, the reaction product obtained from the alkylation reactor enters the acid-hydrocarbon separation coalescer for separation. The liquid acid catalyst is separated from the bottom of the acid-hydrocarbon separator and sent back to the alkylation reactor for recycling. The reaction product from which the acid catalyst has been removed is sent to the product separation tower for separation. Isoparaffin is obtained from the top of the product separation tower and sent back to the alkylation reactor, and the alkylated oil product is obtained from the bottom of the product separation tower; the normal paraffin that does not participate in the reaction and the surplus isoparaffin in the feedstock extracted from the side line of the product separation tower are sent to the paraffin separation tower for separation. High-concentration normal paraffin is extracted from the bottom of the paraffin separation tower, and the high-concentration isoparaffin obtained from the top is returned to the alkylation reactor.

[0058] In a preferred specific embodiment of the present disclosure, a solid acid catalyst is used, such as Figure 2As shown, the separation device includes a product separation column 3 and a butane separation column 4 to separate the mixed materials produced by the alkylation reaction. The present invention will be further described below by way of examples, but the present invention is not limited thereby.

[0059] Unless otherwise specified, various reagents and raw materials used in the present invention are commercially available products or products that can be prepared by well-known methods.

[0060] Example 1

[0061] As Figure 1 shown, using a liquid acid catalyst, the process system of this example includes: an alkylation reactor 1, an acid-hydrocarbon separation coalescer 2, a product separation column 3, and a butane separation column 4; among them, the alkylation reactor 1 is a shell-and-tube reactor, and the composition of the mixed raw material S1 (carbon four raw material after etherification) containing isoparaffin and olefin is shown in Table 1.

[0062] The carbon four raw material S1 after etherification containing isoparaffin and olefin, which has been pretreated by raw materials, is fed into the shell-and-tube alkylation reactor 1, contacts with the liquid acid catalyst dodecylbenzenesulfonic acid, and is mixed evenly under the action of a disperser, and then enters the tube side of the reactor for alkylation reaction to obtain an alkylation reaction product S2. The tube side of the reactor is equipped with packing to further make the carbon four raw material after etherification containing isoparaffin and olefin mix more evenly with the liquid acid catalyst. Among them, the concentration of the liquid acid catalyst dodecylbenzenesulfonic acid in the alkylation reaction system is 0.8 wt%, the alkylation reaction temperature is 120 °C, and the reaction pressure is 3.2 Mpa.

[0063] Among them, the heat removal medium of the shell-and-tube reactor uses circulating water. The circulating water is fed into the shell side of the reactor through the heat removal medium inlet 5 of the alkylation reactor 1, countercurrently removes heat from the mixed raw materials of the shell-and-tube reactor, and the circulating water that absorbs heat is discharged through the heat removal medium outlet 6 of the alkylation reactor 1 and enters the subsequent utilization section. Among them, the temperature of the mixed raw material inlet of the shell-and-tube reactor is 110 °C, and the temperature of the circulating water inlet is 80 °C.

[0064] Let the product S2 obtained from the alkylation reactor enter the acid-hydrocarbon separation coalescer 2 for separation. The recycled acid catalyst S8 separated from the bottom of the acid-hydrocarbon separation coalescer 2 is sent back to the alkylation reactor 1 for recycling. The reaction product S3 from which the acid catalyst has been removed is sent to the product separation tower 3 for separation. The isobutane component S6 is obtained from the top of the product separation tower 3 and sent back to the alkylation reactor 1, and the alkylated oil product S9 is obtained from the bottom of the product separation tower 3. The unreacted n-butane drawn from the side line of the product separation tower 3 and the unreacted isobutane S4 in the etherified C4 raw material are sent to the butane separation tower 4 for separation. High-concentration n-butane S5 can be obtained from the bottom of the butane separation tower 4 and used as a raw material for the maleic anhydride unit, and the high-concentration isobutane S7 obtained from the top is returned to the reactor. Fresh acid catalyst S10 is supplemented at the feed inlet of the alkylation reactor 1 to control the mass concentration of the liquid acid catalyst in the alkylation reaction system. The reaction results are shown in Table 2.

[0065] Example 2

[0066] The process flow and method of Example 1 are adopted, with the only difference being that the alkylation reaction temperature is 50 °C and the reaction pressure is 2.0 Mpa. The inlet temperature of the mixed raw materials in the tubular reactor is 40 °C, and the inlet temperature of the circulating water is 40 °C. The reaction results are shown in Table 2.

[0067] Example 3

[0068] The process flow and method of Example 1 are adopted, with the only difference being that the alkylation reaction temperature is 160 °C and the reaction pressure is 5.0 Mpa. The inlet temperature of the mixed raw materials in the tubular reactor is 150 °C, and the inlet temperature of the circulating water is 90 °C. The reaction results are shown in Table 2.

[0069] Example 4

[0070] The process flow and method of Example 1 are adopted, with the only difference being that the catalyst used is a commercially available industrial concentrated sulfuric acid with a sulfuric acid mass fraction of 98%, and its concentration in the alkylation reaction system is 0.05 wt%. The reaction results are shown in Table 2.

[0071] Example 5

[0072] As Figure 2 shown, a solid acid catalyst is used. The etherified C4 raw material S1 containing isoparaffin and olefin after raw material pretreatment is sent into the tubular alkylation reactor 1, and is mixed evenly under the action of a disperser, and then enters the tube side of the reactor for alkylation reaction. The solid acid catalyst acidic molecular sieve MCM-41 is filled in the heat exchange tube side of the reactor. The etherified C4 raw material is in full contact with the solid acid catalyst for alkylation reaction to obtain the alkylation reaction product S2. Among them, the alkylation reaction bed temperature of the solid acid catalyst is 120 °C, the reaction pressure is 3.2 Mpa, and the liquid hourly space velocity of the olefin is 1.2 h -1, the inlet temperature of the raw materials is 110°C, and the inlet temperature of the circulating water is controlled at 90°C.

[0073] The product separation process method obtained from the alkylation reactor is the same as the liquid acid alkylation product separation method in Example 1, except that it is not necessary to pass through the acid-hydrocarbon separation coalescer 2 to separate the acidic catalyst. The reaction results are shown in Table 2.

[0074] Example 6

[0075] Adopt the process flow and method of Example 5, the difference is only that the heat exchange tubes of the shell-and-tube reactor are filled with a solid acidic catalyst: high-temperature styrene-based sulfonic acid resin (purchased from Dandong Mingzhu Resin Co., Ltd.), the bed temperature of the solid acid catalyst is 70°C, the reaction pressure is 2.1 Mpa, the inlet temperature of the raw materials is 65°C, and the inlet temperature of the circulating water is controlled at 60°C. The reaction results are shown in Table 2.

[0076] Comparative Example 1

[0077] Adopt the process flow and method of Example 1, the difference is only that the reverse alkylation reactor is a fixed-bed reactor, the reaction temperature of the alkylation reaction is 3°C, the reaction pressure is 0.35 MPa, the liquid acid catalyst uses commercially available industrial concentrated sulfuric acid with a sulfuric acid mass fraction of 98%, and the reaction heat of the alkylation reaction is taken away by isobutane vaporization, and after being pressurized by a compressor and refrigerated by an ice machine, it returns to the inlet of the alkylation reactor. The reaction results are shown in Table 2.

[0078] Comparative Example 2

[0079] Adopt the process flow and method of Example 5, and the total loading amount of the solid acid catalyst acidity is kept consistent with that of Example 5. The difference is only that the alkylation reactor uses a fixed-bed reactor, and the circulating isobutane entering the reactor is cooled to offset the reaction heat released by the alkylation reaction. The reaction results are shown in Table 2.

[0080] Test Example

[0081] (1) The octane number and heat production of the alkylated oil in Examples 1-6 and Comparative Examples 1-2 were tested in the following manner, and the test results are listed in Table 2:

[0082] The octane number of the alkylated oil was determined by GB / T 5487-2015 (Research Method).

[0083] The heat production was calculated by the following formula:

[0084] When the alkylation reaction is a liquid-liquid reaction, the standard enthalpy of formation of isooctane in the liquid state is -259.20 kJ / mol, and the standard specific heat capacity in the liquid phase is 238.55 J / mol·K; the standard enthalpy of formation of isobutane in the liquid state is -154.2 kJ / mol, and the standard specific heat capacity in the liquid phase is 141.64 J / mol·K; the standard enthalpy of formation of 1-butene in the liquid state is -20.8 kJ / mol, and the standard specific heat capacity in the liquid phase is 118.8 J / mol·K; since the heat release of other olefins such as 2-butene is close to that of 1-butene, therefore, the heat released by the alkylation reaction of 1-butene is used to represent the heat released during the entire alkylation reaction process, as follows:

[0085] H0 = (∑H 产物 - ∑H 原料 )

[0086] = (-259.20 kJ / mol) – ((-154.2 kJ / mol) + (-21.1 kJ / mol))

[0087] = -83.9 kJ / mol, or -736 kJ / kg

[0088] Therefore, under standard conditions, the reaction of isobutane and 1-butene to produce alkylate is a strongly exothermic reaction, and the heat of reaction is -83.9 kJ / mol or -736 kJ / kg.

[0089] When the reaction temperature changes, the change in its reaction enthalpy is:

[0090] △H’ = △H0 + ∑Ci△T

[0091] = (-83.9 kJ / mol) + △T × (128.9 + 141.64 - 238.55) J / mol·K

[0092] = (-83.9 + 0.032 × △T) kJ / mol

[0093] When the temperature is 120 °C, that is, △T = 120 K, substituting it in gives △H’ = -80.1 kJ / mol, or -702.28 kJ / kg.

[0094] (2) The acid consumption of the liquid acid catalyst is the amount of the liquid acid catalyst consumed per ton of alkylate produced.

[0095] (3) In Example 5, Example 6 and Comparative Example 2, when a solid acid catalyst is used and the conversion rate of the reaction olefin is lower than 90%, the tubular reactor is cut out for catalyst regeneration, and the results of the single-cycle operation time of the catalyst are listed in Table 2:

[0096] Table 1 Composition of C4 raw materials after etherification (wt%)

[0097] n-butane isobutane n-butene trans-butene cis-butene isobutene C5 22.78 49.26 4.77 13.44 9.18 0.51 0.07

[0098] Table 2 Results of the alkylation reaction

[0099]

[0100] It can be seen from the reaction results in Table 2 that compared with the comparative examples, the high-temperature alkylation process provided by the present invention can accurately control the inlet temperature of the reactor and effectively remove heat from the bed temperature by using a shell-and-tube reactor, reducing the generation of side reactions, thereby ensuring the long-term operation of the solid acid catalyst and greatly reducing the number of regeneration operations of the solid acid catalyst; or when using a low-concentration liquid acid catalyst, it can reduce the acid consumption of the liquid acid catalyst, reduce waste acid emissions, and even achieve zero waste acid emissions. The present invention can eliminate the need for a compressor, reducing equipment investment costs and power consumption. At the same time, the heat released during the alkylation reaction can be effectively recovered, significantly reducing the steam consumption of the alkylation process and greatly reducing the production cost of alkylated oil.

[0101] Comparing Example 1 with Comparative Example 1, it can be seen that both use a liquid acid catalyst. By using a shell-and-tube reactor with a heat transfer medium for heat removal, Example 1 can accurately control the inlet temperature of the reactor and the alkylation reaction temperature, eliminating the need for equipment such as compressors and refrigeration equipment, and having the advantages of low equipment investment and low energy consumption. By controlling the mass concentration of the liquid acid catalyst dodecylbenzenesulfonic acid in the reaction system at a low concentration, the acid consumption of the liquid acid catalyst is 12 kg / t of product, greatly reducing the acid consumption of the liquid acid catalyst and reducing waste acid emissions. At the same time, Example 1 can effectively recover about 702.3 kJ / kg of the heat released during the alkylation reaction, greatly improving the energy utilization efficiency and significantly reducing the production cost.

[0102] Comparing Example 5 with Comparative Example 2, it can be seen that both use a solid acid catalyst. Since Comparative Example 2 uses a fixed-bed reactor, it cannot accurately control the bed temperature of the reactor, easily leading to local overheating and generating a large number of by-products, resulting in easy deactivation of the catalyst and a short single-pass operation time of the catalyst. Only after 2 days of operation, regeneration operation is required. In contrast, by using a shell-and-tube reactor and controlling the inlet temperature of the heat transfer medium and the inlet temperature of the shell-and-tube reactor, Example 5 can accurately control the temperature of the fixed-bed catalyst in the reaction and effectively remove heat from the bed, reducing the generation of side reactions, thereby ensuring the long-term operation of the solid acid catalyst. The single-pass operation time of the catalyst is as long as 180 days, significantly increasing the single-cycle operation time of the catalyst and greatly reducing the number of regeneration operations of the solid acid catalyst. At the same time, Example 5 can effectively recover about 702.3 kJ / kg of the heat released during the alkylation reaction, greatly improving the energy utilization efficiency and significantly reducing the production cost.

[0103] The preferred embodiments of the present invention have been described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0104] In addition, it should be noted that, in the various specific technical features described in the above specific embodiments, they can be combined in any appropriate manner without conflict. To avoid unnecessary repetition, the present invention will not separately describe various possible combination manners.

[0105] Furthermore, any combination can be made between various different embodiments of the present invention, as long as it does not violate the idea of the present invention, and it should also be regarded as the content disclosed by the present invention.

Claims

1. A method for preparing alkylated oil, characterized in that: Contact a mixed feedstock containing isoparaffins and olefins with a catalyst in a weak acidic environment in an alkylation reactor to carry out an alkylation reaction; wherein, the alkylation reactor is a shell-and-tube reactor.

2. The method according to claim 1, wherein: The catalyst in the weak acidic environment includes a solid acid catalyst or a liquid acid catalyst; the solid acid catalyst includes a weak acid or an acidic molecular sieve, and the liquid acid catalyst includes a low-concentration strong acid or a very weak acid; the mass concentration of the liquid acid catalyst in the alkylation reaction system is 0.01% to 10%; wherein, the reaction temperature of the alkylation reaction is 40 to 200 °C, and the reaction pressure is 0.5 to 8.0 Mpa.

3. The method according to claim 1 or 2, characterized in that: The reaction heat released by the alkylation reaction is removed by a heat extraction medium in the jacket of the shell-and-tube reactor, and the heat extraction medium includes circulating water and / or jacket water or generates steam; preferably, the inlet temperature of the mixed feedstock of the shell-and-tube reactor is 30 to 190 °C, and the inlet temperature of the heat extraction medium is 35 to 180 °C.

4. The method according to claim 1 or 2, characterized in that: The carbon number of the isoparaffins in the mixed feedstock is 4 to 8, preferably isobutane; the carbon number of the olefins in the mixed feedstock is 3 to 8, preferably at least one of propylene, n-butene, 2-butene, pentene, hexene, heptene, and octene.

5. The method according to claim 1 or 2, characterized in that: The mixed feedstock is selected from at least one of the C4 feedstock after etherification, the C5 feedstock from pyrolysis, and the C6 feedstock after extraction of aromatics; preferably the C4 feedstock after etherification.

6. The method according to claim 1 or 2, characterized in that: The molar ratio of isoparaffins to olefins in the mixed feedstock is 5 to 20, preferably 7 to 12.

7. The method according to claim 2, wherein: The liquid acid catalyst is selected from at least one of sulfuric acid, hydrofluoric acid, dodecylbenzenesulfonic acid, preferably dodecylbenzenesulfonic acid.

8. The method according to claim 2, wherein: The solid acid catalyst is selected from at least one of acidic cation exchange resins, solid phosphoric acid, acidic molecular sieves, preferably acidic molecular sieves.

9. The method according to claim 8, wherein: The conditions of the alkylation reaction further include: the liquid hourly space velocity of olefins in the mixed raw materials relative to the solid acid catalyst is 0.5 to 2.0 h -1 , preferably 1.0 to 2.0 h -1 .

10. The method according to claim 1, characterized in that: Directly send the alkylation reaction product into a separation device through pressure for separation to obtain alkylated oil, unreacted isoparaffins, and optionally recycled catalyst.

11. The method according to claim 1, characterized in that: Heat exchange tubes are arranged in the shell-and-tube reactor, and the heat exchange tubes are filled with a solid acid catalyst that is beneficial to the mixing of reaction media or a filler that can easily make the mixed feedstock and the liquid acid catalyst fully mixed, and the filler is preferably a fiber membrane filler.

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