Production method of isoparaffin solvent oil

Abstract

The invention relates to the field of isoparaffin production, and discloses a production method of isoparaffin solvent oil. The method comprises the following steps: (1) in the presence of a superimposition reaction catalyst, performing superimposition reaction on mixed C4 to obtain a superimposition reaction product containing C8-C12 mixed olefin; (2) carrying out an alkylation reaction on the superposition reaction product of the mixed olefin containing C8-C12 in the step (1) and an alkylate to obtain a mixture containing isoparaffin containing C5-C16; and (3) separating the mixture containing the C5-C16 isoparaffin in the step (2) to obtain the C5-C11 alkylated gasoline and the C12-C16 isoparaffin solvent oil. According to the method, the mixed C4 is used as a reaction raw material, a superposition reaction and an alkylation reaction are combined, the application scene of the mixed C4 is widened, the comprehensive utilization rate of the raw materials is high, the production cost is low, and alkylated gasoline and isoparaffin solvent oil can be produced as byproducts.

Description

Technical Field

[0001] The invention relates to the technical field of isoparaffin production, and in particular to a method for producing isoparaffin solvent oil. Background Art

[0002] As the country continues to pay attention to new energy vehicles, my country's demand for gasoline will show a downward trend, and refinery raw materials will be more inclined to be deeply processed to produce high-value-added chemical products. 4 The deep processing and utilization of C 4 Olefins are mainly used in etherification to produce MTBE, alkylation, isomerization and aromatization to produce alkylated gasoline, etc. How to make better use of C 4 The production of high value-added chemicals is a hot topic in chemical research.

[0003] C 12 , C 16 Isoparaffins are colorless, odorless, high-purity hydrocarbon solvent oils with a single component, stable quality, no aromatics and sulfur, green and environmentally friendly, low freezing point, low odor, low toxicity and good stability, consistent product quality, low surface tension, low density, good low-temperature performance and solvency, etc. In most cases, the application of isoparaffins is no different from that of D series dearomatized solvent oils. Due to their excellent low odor, low aromatic performance and relatively high price, they are mainly used in high-end applications to replace D series dearomatized solvent oils, such as: volatile stamping oil (aluminum fins of air conditioners / aluminum foil for dining boxes) / aerosols / odorless coatings / high-end mold release agents / high-end clothing dry cleaning agents / metal cleaning / special fibers / plastic gloves. At the same time, because it exceeds the safety indicators of D series dearomatized solvent oils, it is unique and irreplaceable in the use of LDPE polymerization initiator carriers / high-end skin care cosmetics and other fields.

[0004] At present, there are three production processes for isoparaffins: isomerization of linear alkanes (representative manufacturers ExxonMobil), isobutylene superposition hydrogenation (representative manufacturers Idemitsu, INEOS, Maruzen), and Fischer-Tropsch synthesis of isoparaffins (domestic coal chemical industry). Among them, the first two processes have high requirements for raw materials and relatively high costs, which makes the cost of high-end solvent oil high. The Fischer-Tropsch process cannot be applied to high-end applications such as food and cosmetics due to its long process, more impurities, and strong odor. Summary of the invention

[0005] The purpose of the present invention is to overcome the problems of high raw material requirements, complex production process and high cost in the production process of isoparaffin solvent oil in the prior art, and to provide a production method of isoparaffin solvent oil. The method uses mixed carbon four as a reaction raw material, combines superposition reaction and alkylation reaction, broadens the applicable scenarios of mixed carbon four, has high comprehensive raw material utilization rate, low production cost, and can produce alkylation gasoline and isoparaffin solvent oil as by-products.

[0006] In order to achieve the above object, the present invention provides a method for producing isoparaffin solvent oil, wherein the method comprises the following steps:

[0007] (1) In the presence of a superposition reaction catalyst, a mixture of carbon four is subjected to superposition reaction to obtain a compound containing C 8 -C 12 A product of a superposition reaction of mixed olefins;

[0008] (2) the C-containing 8 -C 12 The mixed olefin superposition reaction product is subjected to alkylation reaction with an alkylate to obtain a C 5 -C 16 A mixture of isoparaffins;

[0009] (3) the C-containing 5 -C 16 The mixture of isoparaffins is separated to obtain C 5 -C 11 Alkylate gasoline and C 12 -C 16 Isoparaffin solvent oil.

[0010] The production method provided by the present invention uses mixed C4 as a reaction raw material to produce isoparaffin solvent oil. In a preferred case, the C4 of the refinery is fully utilized. 4 Different components in olefins can produce ideal alkylation gasoline components as by-products, broadening the application scenarios of mixed C4 and providing a new development path for mixed C4. Using mixed C4 as the reaction raw material can give full play to the advantages of mixed C4 components, with high comprehensive utilization efficiency of raw materials and simple production process. On the basis of reducing costs, the production of isoparaffin solvent oil can be achieved, which is beneficial to industrial production.

[0011] The production method provided by the invention organically combines superposition reaction and alkylation reaction, and the synthesized isoparaffin solvent oil has a high isoparaffin content, which can be as high as 100%, less impurities, higher isoparaffin purity, and improved product added value. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic diagram of the process flow of the present invention.

[0013] Reference numerals

[0014] 1-Superposition reactor 2-Alkylation reactor

[0015] 3-Separation tower DETAILED DESCRIPTION

[0016] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the 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 as specifically disclosed in this article.

[0017] The present invention provides a method for producing isoparaffin solvent oil, wherein the method comprises the following steps:

[0018] (1) In the presence of a superposition reaction catalyst, a mixture of carbon four is subjected to superposition reaction to obtain a compound containing C 8 -C 12 A product of a superposition reaction of mixed olefins;

[0019] (2) the C-containing 8 -C 12 The mixed olefin superposition reaction product is subjected to alkylation reaction with an alkylate to obtain a C 5 -C 16 A mixture of isoparaffins;

[0020] (3) the C-containing 5 -C 16 The mixture of isoparaffins is separated to obtain C 5 -C 11 Alkylate gasoline and C 12 -C 16 Isoparaffin solvent oil.

[0021] The production method provided by the present invention uses mixed C4 as a reaction raw material to produce isoparaffin solvent oil, which broadens the application scenarios of mixed C4, solves the problem of overproduction of mixed C4 in the prior art, and provides a new development path for mixed C4; using mixed C4 as a reaction raw material can give full play to the advantages of the mixed C4 components, the comprehensive utilization efficiency of raw materials is high, and the production process is simple. On the basis of reducing costs, the production of isoparaffin solvent oil is achieved, which is beneficial to industrial production.

[0022] The production method provided by the invention organically combines superposition reaction and alkylation reaction, and the synthesized isoparaffin solvent oil has a high isoparaffin content, which can be as high as 100%, less impurities, higher isoparaffin purity, and improved product added value.

[0023] In the present invention, there is no particular limitation on the source of the mixed C4 as the reaction raw material, and the mixed C4 obtained in the conventional production process defined in the art is applicable to the present invention. Preferably, in step (1), the mixed C4 comes from at least one of an oil refining process, a coal chemical process and an isoparaffin dehydrogenation process, preferably from an oil refining process. The advantage of adopting this preferred embodiment is that the ratio of alkane and olefin components in the C4 is appropriate, can be fully converted, the solvent oil has a high relative yield of C4 raw materials, and also provides a new development path for mixed C4, which has good industrial value.

[0024] In the present invention, the mixed C4 reaction raw material contains a variety of olefins, and the type of olefins is selected to facilitate the production of isoparaffin solvent oil. Preferably, the mixed C4 contains olefins and / or isobutane. The advantage of adopting this preferred embodiment is that the isobutane in the mixed C4 can be directly used as an alkylate, avoiding subsequent separation and selection of alkylates, simplifying the industrial process, and saving costs.

[0025] In the present invention, preferably, the olefin is selected from at least one of isobutylene, 1-butene and 2-butene.

[0026] In the present invention, by controlling the content of olefins in the mixed carbon four of the reaction raw material, it is beneficial to the production of isoparaffin solvent oil. Preferably, based on the total amount of the mixed carbon four, the mass fraction of the olefin is 30-60%, and the mass fraction of the isobutane is 40-60%; further preferably, based on the total amount of the mixed carbon four, the mass fraction of the olefin is 35-50%, and the mass fraction of the isobutane is 42-50%. By controlling the ratio of olefins and isobutane in the mixed carbon four of the reaction raw material, the distribution of the reaction products can be effectively regulated to obtain the target product.

[0027] In the present invention, by controlling the content of isobutylene in olefins, the production of isoparaffin solvent oil is facilitated. Preferably, based on the total amount of olefins, the mass fraction of isobutylene is above 15%, more preferably above 30%, and more preferably 31-80%. The advantage of adopting this preferred embodiment is that isobutylene is more conducive to superposition to generate isopentene, and the isomerization degree of the final target product solvent oil is higher.

[0028] In the present invention, there is no particular limitation on the type of catalyst used in the superposition reaction, and those skilled in the art can select it according to actual conditions. Preferably, in step (1), the superposition reaction catalyst is a molecular sieve and / or an ion exchange resin, preferably an ion exchange resin, more preferably a cation exchange resin, and more preferably at least one selected from sulfonated styrene-divinylbenzene resin, sulfonated styrene-divinylbenzene high temperature resistant resin in which some hydrogen atoms on the benzene ring are replaced by chlorine, and perfluorosulfonated styrene-divinylbenzene resin.

[0029] In the present invention, there is no particular limitation on the source of the superposition reaction catalyst, and it can be prepared, for example, by a method conventionally defined in the art, or can be commercially obtained.

[0030] In the present invention, preferably, in step (1), the conversion rate of olefins in the mixed C4 is 70-100%, more preferably 90-100%. In the present invention, by controlling the conversion rate of olefins and regulating the distribution of reaction products, the superposition reaction and the alkylation reaction are organically combined, which is conducive to obtaining the target products alkylated gasoline and isoparaffin solvent oil, and increasing the proportion of isoparaffins.

[0031] In the present invention, the conditions for the superposition reaction are relatively wide. Preferably, in step (1), the conditions for the superposition reaction include: a temperature of 130-250°C, a pressure of 3-7 MPa, a mass space velocity of 2-10 h -1 Further preferably, in step (1), the conditions of the superposition reaction include: temperature of 190-220°C, pressure of 4-6MPa, mass space velocity of mixed carbon four of 4-8h -1 .

[0032] In the present invention, preferably, the superposition reaction is a non-selective superposition reaction. It should be noted that the non-selective superposition reaction means that all olefins participate in the superposition reaction to maximize the production of C8 olefins.

[0033] In the present invention, there is no particular limitation on the type of alkylate. Preferably, in step (2), the alkylate is selected from at least one of isobutane, propane and isopentane, preferably isobutane. The use of the alkylate in the above preferred range has the advantage of being more conducive to converting olefins into isoparaffin solvent oil.

[0034] In the present invention, in step (2), the alkylation reaction is carried out in the presence of an alkylation catalyst. In the present invention, there is no particular limitation on the type of the alkylation catalyst. Preferably, the alkylation catalyst is selected from at least one of a liquid acid, an ionic liquid and a solid acid molecular sieve catalyst. In the present invention, there is no particular limitation on the specific type of each alkylation catalyst, and the alkylation catalyst conventionally defined in the art can be applied to the present invention, for example, it can be hydrofluoric acid and / or sulfuric acid.

[0035] In the present invention, there is no particular limitation on the source of the alkylation catalyst. For example, the alkylation catalyst can be prepared by a method conventionally defined in the art, or can be commercially obtained.

[0036] In the present invention, the conditions for the alkylation reaction can be selected in a wide range. Preferably, in step (2), the conditions for the alkylation reaction include: a temperature of 30-200°C, a pressure of 0.5-6 MPa, and a 8 -C 12 The mass ratio of the mixed olefins is 5-1000:1, the alkylate and C 8 -C 12 The feed space velocity of the mixed olefins is 10-3000mL / (g·h); further preferably, in step (2), the conditions of the alkylation reaction include: temperature of 40-80°C, pressure of 1-3MPa, alkylate and C 8 -C 12 The mass ratio of the mixed olefins is 20-200:1, the alkylate and C 8 -C 12 The feed space velocity of the mixed olefins is 20-200 mL / (g·h).

[0037] In the present invention, preferably, the step (1) contains C 8 -C 12 The mixed olefin polymerization product also contains unreacted isobutylene.

[0038] In the present invention, preferably, the method further comprises the step of using the unreacted isobutylene in the superposition reaction of step (1) as the alkylate in step (2) for alkylation reaction without separation. The advantage of adopting this preferred embodiment is that the unreacted isobutane in step (1) can be used as the alkylate in step (2) without separation, and the isobutane can be fully utilized as the alkylate, while the amount of new alkylate added is minimized, thereby simplifying the process and saving production costs.

[0039] In the present invention, preferably, the superposition reaction in step (1) and the alkylation reaction in step (2) are each independently carried out in at least one of a fixed bed reactor, a slurry bed reactor and a moving bed reactor, and more preferably in a fixed bed reactor.

[0040] In the present invention, there is no particular limitation on the methods of the superposition reaction and the alkylation reaction. Preferably, the superposition reaction in step (1) and the alkylation reaction in step (2) are both carried out in a fixed bed reactor, and the two fixed bed reactors are connected in series. Preferably, the superposition reaction product obtained in step (1) (the superposition reaction product includes C 8 -C 12 The mixed olefins and unreacted mixed C4) are directly fed into the alkylation reaction without separation and the alkylation reaction in step (2) is carried out in a solid bed reactor, thereby saving energy consumption. The fixed bed process is also easy to separate the products, which is more environmentally friendly.

[0041] In the present invention, there is no particular limitation on the manner and conditions of separation in step (3). For example, the separation can be carried out in a separation tower, and the separation conditions can be carried out according to conventional operations in the art, and the present invention does not impose any particular limitation on this.

[0042] In the present invention, preferably, the method further comprises obtaining C4 olefins after separation in step (3), and then returning the C4 olefins to step (1) for recycling.

[0043] According to a specific embodiment of the present invention, the method is as follows Figure 1 The system shown in the figure is carried out, the mixed C4 enters the superposition reactor 1 for superposition reaction to obtain C 8 -C 12 The product of the polymerization reaction of mixed olefins containing C 8 -C 12 The superposition reaction product of the mixed olefins and the alkylate enter the alkylation reactor 2 for alkylation reaction to obtain C 5 -C 16 A mixture of isoalkanes; containing C 5 -C 16 The isoparaffin mixture enters the separator 3 for separation to obtain C 5 -C 11 Alkylate gasoline and C 12 -C 16 Isoparaffin solvent oil.

[0044] The present invention will be described in detail below by way of examples. In the following examples, unless otherwise specified, all the raw materials used are commercially available.

[0045] The mixed C4 in the following Examples 1-5 comes from C4 in a refinery, and the composition of the mixed C4 is: isobutane (C 4 H 10 ) 45 mass%, n-butane (C 4 H 10 ) 16 mass%, butene mixture (C 4 H8 ) 39 mass %, of which isobutylene accounts for 40 mass % of the butene mixture.

[0046] In the following examples, Hβ molecular sieve (relative crystallinity 90%, w(Na 2 O)=0.075%) as the alkylation catalyst.

[0047] In the following examples, a superimposed strong acid cation exchange resin catalyst was selected as the superimposed reaction catalyst. The superimposed strong acid cation exchange resin catalyst was purchased from Sinopec Catalyst Co., Ltd., with an exchange capacity of 5.2 mmol H + / g.

[0048] Example 1

[0049] Use the following process and follow Figure 1 The system is used to prepare isoparaffin solvent oil, wherein the reactions of step (1) and step (2) are respectively carried out in two fixed bed reactors, and step (3) is carried out in a separation tower;

[0050] (1) The refinery C4 was used as feed in the first fixed bed reactor (superposition reactor 1) for superposition reaction. The superposition reaction temperature was 190°C, the pressure was 4 MPa, and the feed mass space velocity was 4 h -1 The PONA composition of the superposition reaction product was analyzed by gas chromatography, and the conversion rate of butene in the refinery C4 was 92%.

[0051] (2) The product of the superposition reaction in step (1) was directly used as the olefin source for the alkylation reaction, and then a mixture of isobutane and mixed olefins with a mass ratio of 200 was added to form a feed for the alkylation reaction. The alkylation reaction was carried out in a second fixed bed reactor (alkylation reactor 2) at a reaction temperature of 40° C., a pressure of 1 MPa, and a feed space velocity of 20 mL / (g·h). The composition of the alkylation reaction product was analyzed by gas chromatography and is shown in Table 1.

[0052] (3) The alkylation product obtained in step (2) is separated by separation tower 3, and the C4 fraction at the top of the tower is returned to step (1) for reuse. 5 -C 11 The fractions are alkylation gasoline, bottom C 12 -C 16 It is the isoparaffin solvent oil fraction. The isoparaffin content in the isoparaffin solvent oil fraction is measured by gas chromatography.

[0053] Example 2

[0054] Use the following process and follow Figure 1 The system is used to prepare isoparaffin solvent oil, wherein the reactions of step (1) and step (2) are respectively carried out in two fixed bed reactors, and step (3) is carried out in a separation tower;

[0055] (1) The refinery C4 was used as feed to carry out a superposition reaction in the first fixed bed reactor (superposition reactor 1). The superposition reaction temperature was 220°C, the pressure was 6 MPa, and the feed mass space velocity was 8 h -1 The PONA composition of the superposition reaction product was analyzed by gas chromatography, and the conversion rate of C4 in the refinery was 91%.

[0056] (2) The product of the superposition reaction in step (1) was directly used as the olefin source for the alkylation reaction, and then a mixture of isobutane and mixed olefins in a mass ratio of 100 was added to form a feed for the alkylation reaction. The alkylation reaction was carried out in a second fixed bed reactor (alkylation reactor 2) at a reaction temperature of 80° C., a pressure of 3 MPa, and a feed space velocity of 200 mL / (g·h). The composition of the alkylation reaction product was analyzed by gas chromatography and is shown in Table 1.

[0057] (3) The alkylation product obtained in step (2) is separated by separation tower 3, and the C4 fraction at the top of the tower is returned to step (1) for reuse. 5 -C 11 The fractions are alkylation gasoline, bottom C 12 -C 16 It is the isoparaffin solvent oil fraction. The isoparaffin content in the isoparaffin solvent oil fraction is measured by gas chromatography.

[0058] Example 3

[0059] Use the following process and follow Figure 1 The system is used to prepare isoparaffin solvent oil, wherein the reactions of step (1) and step (2) are respectively carried out in two fixed bed reactors, and step (3) is carried out in a separation tower;

[0060] (1) The refinery C4 was used as feed in the first fixed bed reactor (superposition reactor 1) for superposition reaction. The superposition reaction temperature was 200°C, the pressure was 5 MPa, and the feed mass space velocity was 6 h -1 The PONA composition of the superposition reaction product was analyzed by gas chromatography, and the conversion rate of olefins in the refinery C4 was 94%.

[0061] (2) The product of the superposition reaction in step (1) was directly used as the olefin source for the alkylation reaction, and then a mixture of isobutane and mixed olefins in a mass ratio of 20 was added to form a feed for the alkylation reaction. The alkylation reaction was carried out in a second fixed bed reactor (alkylation reactor 2) at a reaction temperature of 50° C., a pressure of 2 MPa, and a feed space velocity of 30 mL / (g·h). The composition of the alkylation reaction product was analyzed by gas chromatography and is shown in Table 1.

[0062] (3) The alkylation product obtained in step (2) is separated by separation tower 3, and the C4 fraction at the top of the tower is returned to step (1) for reuse.5 -C 11 The fractions are alkylation gasoline, bottom C 12 -C 16 It is the isoparaffin solvent oil fraction. The isoparaffin content in the isoparaffin solvent oil fraction is measured by gas chromatography.

[0063] Example 4

[0064] The method of Example 1 was followed, except that isopentane was used instead of isobutane. The composition of the alkylation reaction product was analyzed by gas chromatography, and the conversion rate of olefins in the superposition reaction product was 99.91%. The content of isoparaffins in the isoparaffin solvent oil fraction was measured by gas chromatography.

[0065] Example 5

[0066] Use the following process and follow Figure 1 The system is used to prepare isoparaffin solvent oil, wherein the reactions of step (1) and step (2) are respectively carried out in two fixed bed reactors, and step (3) is carried out in a separation tower;

[0067] (1) The refinery C4 was used as feed to carry out a superposition reaction in the first fixed bed reactor (superposition reactor 1). The superposition reaction temperature was 170°C, the pressure was 3.5 MPa, and the feed mass space velocity was 5 h -1 The PONA composition of the superposition reaction product was analyzed by gas chromatography, and the conversion rate of olefins in the refinery C4 was 85%.

[0068] (2) The product of the superposition reaction in step (1) was directly used as the olefin source for the alkylation reaction, and then a mixture of isobutane and mixed olefins in a mass ratio of 100 was added to form a feed for the alkylation reaction. The alkylation reaction was carried out in a second fixed bed reactor (alkylation reactor 2) at a reaction temperature of 30° C., a pressure of 5 MPa, and a feed space velocity of 210 mL / (g·h). The composition of the alkylation reaction product was analyzed by gas chromatography and is shown in Table 1.

[0069] (3) The alkylation product obtained in step (2) is separated by separation tower 3, and the C4 fraction at the top of the tower is returned to step (1) for reuse. 5 -C 11 The fractions are alkylation gasoline, bottom C 12 -C 16 It is the isoparaffin solvent oil fraction. The isoparaffin content in the isoparaffin solvent oil fraction is measured by gas chromatography.

[0070] Example 6

[0071] The method of Example 1 is different in that the reaction raw material mixed carbon four comes from the refinery carbon four, isobutane (C 4 H 10) 23 mass%, n-butane (C 4 H 10 ) 7 mass%, butene mixture (C 4 H 8 ) 70 mass %, of which isobutylene accounts for 15 mass % of the butene mixture.

[0072] The following process is used to prepare isoparaffin solvent oil, wherein the reactions of step (1) and step (2) are respectively carried out in two fixed bed reactors, and step (3) is carried out in a separation tower;

[0073] (1) The PONA composition of the superposition reaction product was analyzed by gas chromatography, and the conversion rate of olefins in the refinery C4 was 80%.

[0074] (2) The composition of the alkylation reaction product was analyzed by gas chromatography and is shown in Table 1. The content of isoparaffin in the isoparaffin solvent oil fraction was measured by gas chromatography.

[0075] Table 1

[0076] <![CDATA[C 5 -C 11 / Mass%]]> <![CDATA[C 12 -C 16 / Mass%]]> <![CDATA[C 12 / Mass%]]> Isoparaffin proportion / % Example 1 67.8 32.2 12.3 100 Example 2 70.5 29.5 11.8 100 Example 3 68.1 31.9 11.5 100 Example 4 65.8 34.2 10.8 99.5 Example 5 64.6 35.4 11.2 99.3 Example 6 73.3 26.7 9.8 98.5

[0077] It can be seen from the results in Table 1 that the method of the present invention uses mixed C4 as a raw material and combines the superposition reaction with the alkylation reaction to produce alkylated gasoline and solvent oil. The isoparaffin content in the solvent oil is relatively high, and the added value of the product is increased.

[0078] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for producing isoparaffin solvent oil, characterized in that: The method comprises the following steps: (1) In the presence of a superposition reaction catalyst, a mixture of carbon four is subjected to superposition reaction to obtain a mixture containing C8-C 12 A product of a superposition reaction of mixed olefins; (2) the C8-C 12 The mixed olefin superposition reaction product is subjected to alkylation reaction with an alkylate to obtain a C5-C 16 A mixture of isoparaffins; (3) the C5-C 16 The mixture of isoparaffins is separated to obtain C5-C 11 Alkylate gasoline and C 12 -C 16 Isoparaffin solvent oil.

2. The method according to claim 1, wherein: In step (1), the mixed C4 is derived from at least one of an oil refining process, a coal chemical process and an isoparaffin dehydrogenation process, preferably from an oil refining process; Preferably, the mixed C4 contains olefins and / or isobutane; Preferably, the olefin is selected from at least one of isobutylene, 1-butene and 2-butene; Preferably, based on the total amount of mixed C4, the mass fraction of the olefin is 30-60%, and the mass fraction of the isobutane is 40-60%; Further preferably, based on the total amount of mixed C4, the mass fraction of the olefin is 35-50%, and the mass fraction of the isobutane is 42-50%; Preferably, based on the total amount of olefins, the mass fraction of isobutylene is above 15%, more preferably above 30%, and even more preferably 31-80%.

3. The method according to claim 1 or 2, wherein: In step (1), the superposition reaction catalyst is a molecular sieve and / or an ion exchange resin, preferably an ion exchange resin, and more preferably a cation exchange resin.

4. The method according to claim 2 or 3, wherein: In step (1), the conversion rate of olefins in the mixed C4 is 70-100%, preferably 90-100%.

5. The method according to any one of claims 1 to 4, wherein: In step (1), the conditions of the superposition reaction include: temperature of 130-250°C, pressure of 3-7 MPa, mass space velocity of mixed C4 of 2-10 h -1 ; Preferably, in step (1), the conditions of the superposition reaction include: temperature of 190-220°C, pressure of 4-6 MPa, mass space velocity of mixed C4 of 4-8 h -1 .

6. The method according to any one of claims 1 to 5, wherein: In step (2), the alkylate is selected from at least one of isobutane, isopentane and propane, preferably isobutane.

7. The method according to any one of claims 1 to 6, wherein: In step (2), the alkylation reaction is carried out in the presence of an alkylation catalyst; Preferably, the alkylation catalyst is selected from at least one of a liquid acid, an ionic liquid and a solid acid molecular sieve catalyst.

8. The method according to any one of claims 1 to 7, wherein: In step (2), the conditions of the alkylation reaction include: temperature of 30-200°C, pressure of 0.5-6MPa, alkylation product and C8-C 12 The mass ratio of the mixed olefins is 5-1000:1, alkylate and C8-C 12 The feed space velocity of the mixed olefins is 10-3000 mL / (g·h).

9. The method according to claim 8, wherein: In step (2), the conditions of the alkylation reaction include: temperature of 40-80°C, pressure of 1-3 MPa, alkylation product and C8-C 12 The mass ratio of mixed olefins is 20-200:1, alkylate and C8-C 12 The feed space velocity of the mixed olefins is 20-200 mL / (g·h).

10. The method according to any one of claims 1 to 9, wherein: Step (1) contains C8-C 12 The mixed olefin superposition reaction product also contains unreacted isobutylene; Preferably, the method further comprises using the unreacted isobutylene in the superposition reaction of step (1) as the alkylate of step (2) for alkylation reaction without separation; Preferably, the superposition reaction in step (1) and the alkylation reaction in step (2) are each independently carried out in at least one of a fixed bed reactor, a slurry bed reactor and a moving bed reactor, and more preferably in a fixed bed reactor.

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