Conversion method of mixed C4 and mixed C4-maleic anhydride polymer

Abstract

The invention provides a conversion method of mixed C4 and a mixed C4-maleic anhydride polymer. The conversion method comprises the following steps: S1, under the action of a catalyst, carrying out an isomerization reaction on n-butene in mixed C4 to convert n-butene into isobutene so as to obtain a C4 mixed concentrated material; and S2, mixing the C4 mixed concentration material, maleic anhydride, an initiator and an organic solvent, and carrying out a polymerization reaction to obtain a mixed C4-maleic anhydride polymer and inactive C4. According to the mixed C4-maleic anhydride polymer, n-butene in the mixed C4 is converted into isobutene through an isomerization reaction, the content of isobutene in the mixed C4 is increased, the mixed C4 and maleic anhydride are subjected to a polymerization reaction, the generated mixed C4-maleic anhydride polymer is uniform in molecular weight and particle size distribution, and the quality and the application value of the mixed C4-maleic anhydride polymer are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of recycling of mixed C4, and in particular, to a method for converting mixed C4 and a mixed C4-maleic anhydride polymer. Background Art

[0002] Due to the development of industries such as oil refining and coal chemical industry in China, a large amount of mixed C4 resources have been generated. Mixed C4 is mostly used as liquefied fuel, but with the development of natural gas development and utilization technology, the use of liquefied fuel has been decreasing year by year. Therefore, the utilization rate of mixed C4 is low, and the added value of C4 products is also low. How to reasonably and fully utilize C4 fractions, improve the utilization rate of mixed C4 resources and the added value of products, is a problem widely concerned by the industry and academia. At present, the main components of C4 hydrocarbons usually include n-butane, isobutane, isobutene, butadiene, 1-butene and 2-butene, etc., and the C4 components produced by different processing methods also have differences. Many existing processes mostly only utilize one component in mixed C4 to improve the utilization rate of this component. For example, isobutene is widely used in the preparation of methyl tert-butyl ether and 1-butene, etc. However, many processes basically require relatively cumbersome separation and purification processes, with high operation difficulty and economic cost.

[0003] The application fields of high molecular polymers are relatively wide, such as the electronic information industry, liquid crystal display industry, coatings, leather, adhesives, battery membranes, paper surface processing, etc. Polymers can be mainly applied as plastic additives to increase performance indicators such as the toughness of plastics. The most common one is ABS resin, but the impact resistance of ABS resin is weak. Therefore, after adding butadiene polymer microspheres to the above resin, its impact resistance can be improved, making it widely used in daily life. The polymers applied in the adhesive industry are mainly core-shell structured polymer microspheres. The shell structure is mainly used to show the viscosity of the adhesive, while the core structure is mainly used to enhance its viscosity. After the polymerization microspheres are compounded with materials, adhesives with room temperature film-forming and excellent biodegradability can be prepared. This type of adhesive is widely used in the wood products industry and has great development potential.

[0004] CN111285968 A discloses a preparation method of a highly alternating and controllable molecular weight maleic anhydride-isobutene copolymer. This method uses an autoclave to stir and mix maleic anhydride with a solvent, and then introduces isobutene gas and a solvent containing an initiator into the autoclave for reaction; then the obtained mixed system of the reaction is filtered, and the filter cake is washed with a polar organic solvent and water, and dried to obtain a maleic anhydride-isobutene copolymer. CN1175592A discloses a method for synthesizing an alternating isobutene-maleic anhydride resin, characterized in that using isobutene and maleic anhydride as the main raw materials, under the action of an initiator, at a certain temperature and pressure, maleic anhydride and ethylene in the mixture form a copolymer resin.

[0005] However, in the above-mentioned studies, the polymerization reaction is mostly carried out using pure isobutene and maleic anhydride. Pure isobutene needs to be obtained through steps such as separation and purification, which greatly increases the complexity of the process.

[0006] CN107722177 A discloses a method for utilizing mixed C4. The method includes: (1) under nitrogen, in the presence of an initiator and an organic solvent, copolymerizing part or all of the terminal olefins in the material containing mixed C4 with maleic anhydride; (2) separating the gas and liquid of the product obtained in step (1) to obtain a gas-phase product and a liquid-solid mixture; based on the total weight of the gas-phase product, the content of terminal olefins in the gas-phase product is 1 wt% or less, and the content of 1,3-butadiene is 0.1 wt% or less; (3) subjecting the gas-phase product obtained in step (2) to steam cracking reaction, and returning the cracked gas to the material in step (1); (4) separating the liquid-solid mixture obtained in step (2) to obtain a solid product which is a polymer containing maleic anhydride functional groups; the mixed C4 is a mixture containing C4 hydrocarbon compounds, and this method can convert the mixed C4 into a raw material for functional materials for utilization. Although the yield of the polymerization product of mixed C4 and maleic anhydride is increased compared with the traditional autoclave polymerization method, during the steam cracking process, the cracking reaction temperature reaches above 700 °C, which greatly increases the energy consumption in the preparation process and increases the cost. During the cracking process of mixed C4, a large amount of C4 alkanes will be cracked, generating more impurities in the mixed C4, resulting in uncontrollable molecular weight of the polymer, and the alkanes in the mixed C4 cannot be purified, reducing the utilization rate of the mixed C4. Summary of the Invention

[0007] The main object of the present invention is to provide a method for converting mixed C4 and a mixed C4-maleic anhydride polymer, so as to solve the problems of complex recovery and utilization process and low utilization rate of mixed C4 in the prior art.

[0008] To achieve the above object, according to one aspect of the present invention, a method for converting mixed C4 is provided. The conversion method includes: Step S1, under the action of a catalyst, isomerizing the normal butene in the mixed C4 to isobutene to obtain a concentrated C4 mixed material; Step S2, mixing the concentrated C4 mixed material, maleic anhydride, an initiator and an organic solvent, and carrying out a polymerization reaction to obtain a mixed C4-maleic anhydride polymer and inactive C4.

[0009] Further, the catalyst is an acidic solid catalyst. Preferably, the catalyst is any one or more of ZSM-22, ZSM-23, SAPO-11, MeAPO-11, Fe-ZSM-5 and ZSM-35; More preferably, the feed space velocity of the mixed C4 is 0.1~2 h -1 ;

[0010] And / or, the temperature of the isomerization reaction is 250 - 400 °C, and the pressure is 0 - 2 MPa.

[0011] Furthermore, the molar ratio of isobutene to n-butene in the C4 mixed and concentrated material is 5 - 20:1;

[0012] Preferably, the content of isobutene in the C4 mixed and concentrated material is 20% - 40%;

[0013] Preferably, step S1 includes: under the action of a catalyst, isomerizing n-butene in the mixed C4 into isobutene, performing gas-liquid separation on the isomerized product, and collecting the gas phase as the C4 mixed and concentrated material; preferably, the gas-liquid separation is carried out in a condensation tank, and the temperature of the condensation tank is 25 - 35 °C.

[0014] Furthermore, the mass ratio of the C4 mixed and concentrated material to maleic anhydride is 0.5 - 20:1, preferably 2 - 10:1;

[0015] Preferably, the C4 mixed and concentrated material is subjected to water treatment before mixing.

[0016] Furthermore, the initiator is a thermal decomposition type initiator. Preferably, the initiator is selected from at least one or more of benzoyl peroxide, diisopropylbenzene peroxide, ditert-butyl peroxide, lauroyl peroxide, tert-butyl perbenzoate, diisopropyl peroxydicarbonate, dicyclohexyl peroxydicarbonate, azobisisobutyronitrile, and azobisisoheptonitrile; preferably, the mass ratio of the initiator to maleic anhydride is 0.01 - 0.20:1;

[0017] And / or, the organic solvent includes at least one of organic acid alkyl esters, alkanes, and aromatic hydrocarbons; preferably, the organic solvent is selected from any one or more of isopentyl acetate, ethyl acetate, and propyl acetate. Preferably, the proportion of maleic anhydride in the organic solvent is 5% wt. - 25% wt.

[0018] Furthermore, the polymerization reaction is carried out in an inert gas atmosphere;

[0019] And / or, the temperature of the polymerization reaction is 60 °C - 100 °C, the pressure is 0.2 MPa - 1.0 MPa, and the reaction time is 5 - 10 h.

[0020] Furthermore, the mixed C4 is a mixture containing C4 hydrocarbon compounds generated during the petroleum processing and refining process;

[0021] Preferably, the content of C4 olefins in the mixed C4 is 48% - 55%, and the content of alkanes in the mixed C4 is 45% - 50%.

[0022] Further, step S2 includes: step S21, mixing a C4 mixed and concentrated material, maleic anhydride, an initiator, and an organic solvent, and performing a polymerization reaction to obtain a polymerization reaction product system; step S22, performing gas-liquid separation on the polymerization reaction product system to obtain a gas-phase product and a liquid-solid mixture; preferably, returning the gas-phase product to step S1 for isomerization reaction; step S23, performing liquid-solid separation on the liquid-solid mixture to obtain a solid-phase product and a liquid-phase product, washing and drying the solid-phase product to obtain a mixed C4-maleic anhydride polymer; preferably, returning the liquid-phase product to step S21 for polymerization reaction;

[0023] Optionally, the method for liquid-solid separation is centrifugal separation, the rotation speed of the centrifugal separation is 4000-8000 rpm, and the time for centrifugal separation is 10-30 min;

[0024] Preferably, the washing is performed using alcohols and / or alkanes. The alcohols include any one or more of ethanol, methanol, and isopropanol; the alkanes include any one or more of n-hexane, hexane, and cyclohexane.

[0025] According to another aspect of the present application, there is provided a mixed C4-maleic anhydride polymer, which is prepared by the conversion method of the mixed C4 described above.

[0026] Further, the molecular weight of the mixed C4-maleic anhydride polymer is 41000-70000, and the dispersion coefficient is less than or equal to 1.15; preferably, the number average particle size of the mixed C4-maleic anhydride polymer is 0.2-2.0 μm.

[0027] Applying the technical solution of the present invention, the n-butene in the mixed C4 is converted into isobutene through an isomerization reaction, the content of isobutene in the mixed C4 is increased, and it is polymerized with maleic anhydride to generate a mixed C4-maleic anhydride polymer with relatively uniform molecular weight and particle size distribution, improving its quality and application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The specification drawings forming a part of the present application are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0029] Figure 1 The schematic diagram of the conversion method of the mixed C4 according to the embodiment of the present invention is shown.

[0030] Among them, the above-mentioned drawings include the following reference numerals: 1. Mixed C4 gas tank; 2. Fixed-bed reactor; 3. Gas filtration tank; 4. Plunger pump; 5. Solution preheating tank; 6. Polymerization reactor; 7. Gas-liquid separator; 8. Solid-liquid separator; 9. Solid washing tank; 10. Dryer. Detailed implementation manners

[0031] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments may be combined with each other. The present invention will be described in detail below with reference to the drawings and in combination with the embodiments.

[0032] As analyzed in the background art of the present application, there are problems in the prior art such as complex recovery and utilization processes of mixed C4 and low utilization rates. To solve this problem, the present application provides a method for converting mixed C4 and a mixed C4-maleic anhydride polymer.

[0033] According to a typical implementation manner of the present application, a method for converting mixed C4 is provided. The conversion method includes: Step S1, under the action of a catalyst, isomerizing n-butene in the mixed C4 to isobutene to obtain a concentrated C4 mixed material; Step S2, mixing the concentrated C4 mixed material, maleic anhydride, initiator and organic solvent, and carrying out a polymerization reaction to obtain a mixed C4-maleic anhydride polymer and inactive C4.

[0034] In the above-mentioned method for converting mixed C4, n-butene in the mixed C4 is converted to isobutene through an isomerization reaction, the content of isobutene in the mixed C4 is increased, and it is polymerized with maleic anhydride to generate a mixed C4-maleic anhydride polymer with relatively uniform molecular weight and particle size distribution, improving its quality and application value.

[0035] On the other hand, while obtaining the mixed C4-maleic anhydride polymer, the inactive C4 therein is recovered. The main components of the inactive C4 are C4 alkanes and internal olefins containing 4 carbons. The content of terminal olefins in the inactive C4 is relatively low, which is convenient for subsequent conversion or separation and purification, further improving the added value of the mixed C4.

[0036] The above-mentioned mixed C4 is a mixture mainly composed of hydrocarbon compounds containing four carbons. For example, it is a mixture containing C4 hydrocarbon compounds generated during the petroleum processing and refining process. In some embodiments of the present application, the content of C4 olefins in the mixed C4 is 48% - 55%, and the content of alkanes in the mixed C4 is 45% - 50%. Among them, the C4 olefins are any one or more of n-butene, isobutene, cis-butene and trans-butene. In some preferred embodiments of the present application, the content of n-butene in the mixed C4 is 10% - 25%, and the content of isobutene is 15% - 18%, and the conversion efficiency by the method of the present application is relatively high.

[0037] To improve the conversion rate of the isomerization reaction, the catalyst used in the above isomerization reaction is an acidic solid catalyst. In some preferred embodiments of the present application, the catalyst is any one or more of ZSM-22, ZSM-23, SAPO-11, MeAPO-11, Fe-ZSM-5, and ZSM-35.

[0038] To improve the conversion rate of the above-mentioned n-butene in the mixed C4, preferably, the feed space velocity of the mixed C4 is 0.1 - 2 h -1 .

[0039] In some embodiments of the present application, the temperature of the isomerization reaction is 250 - 400 °C, and the pressure is 0 - 2 MPa, and the conversion rate of n-butene is relatively high.

[0040] In some embodiments of the present application, the molar ratio of isobutene to n-butene in the C4 mixed enrichment material is 5 - 20:1, which is beneficial to improving the molecular weight and particle size distribution uniformity of the mixed C4-maleic anhydride polymer. Exemplarily, the molar ratio of isobutene to n-butene in the C4 mixed enrichment material can be 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, 16:1, 17:1, 18:1, 19:1, 20:1, or any range between any two of them.

[0041] In some typical embodiments of the present application, in order to further improve the performance of the mixed C4-maleic anhydride polymer, the content of isobutene in the C4 mixed enrichment material obtained after the first isomerization of the mixed C4 is 20% - 40%. Concentrating the isobutene in the mixed C4 to this concentration is beneficial to obtaining a mixed C4-maleic anhydride polymer with a more uniform molecular weight distribution. Exemplarily, the content of isobutene in the C4 mixed enrichment material is 20%, 25%, 28%, 30%, 32%, 35%, 38%, 40%, or any range between any two of them.

[0042] In some preferred embodiments of the present application, step S1 includes: under the action of a catalyst, isomerizing the n-butene in the mixed C4 to isobutene, separating the isomerized product into gas and liquid, collecting the gas phase as the C4 mixed enrichment material, and most of the liquid phase is the C8 component, accounting for about 1% of the total mass. This part of the C8 component can be recycled. In some embodiments of the present application, the gas-liquid separation is carried out in a condensation tank, and the temperature of the condensation tank is 25 - 35 °C, which is beneficial to improving the efficiency of gas-liquid separation.

[0043] In some embodiments of the present application, in step S2, the mass ratio of the concentrated C4 mixed material to maleic anhydride is 0.5 to 20:1, preferably 2 to 10:1, which is beneficial to further improve the yield of the C4-maleic anhydride polymer and the product quality.

[0044] In some preferred embodiments of the present application, before the concentrated C4 mixed material is mixed with other reaction materials, water treatment is carried out to prevent water vapor from being brought into the polymerization reaction environment and having an adverse effect on the polymerization effect, which is beneficial to further improve the efficiency of the polymerization reaction and the performance of the polymerization product. In some embodiments of the present application, a filter tube filled with a desiccant is installed at the inlet of the concentrated C4 mixed material entering the polymerization reactor to filter the water vapor in the concentrated C4 mixed material.

[0045] The initiator in the above polymerization reaction can be selected from the prior art. Preferably, the initiator is a thermal decomposition type initiator. In some embodiments of the present application, the initiator is selected from at least one or more of benzoyl peroxide, diisopropylbenzene peroxide, di-tert-butyl peroxide, lauroyl peroxide, tert-butyl perbenzoate, diisopropyl peroxydicarbonate, dicyclohexyl peroxydicarbonate, azobisisobutyronitrile, and azobisisoheptonitrile. Preferably, the mass ratio of the initiator to maleic anhydride is 0.01 to 0.20:1, which has a more suitable polymerization rate and is beneficial to further improve the molecular weight distribution of the polymerization product and the uniformity of the particle size.

[0046] The above organic solvent needs to have good solubility for the initiator and maleic anhydride, and those skilled in the art can select from the prior art. In some embodiments of the present application, the organic solvent includes at least one of organic acid alkyl esters, alkanes, and aromatic hydrocarbons.

[0047] For example, the organic acid alkyl ester can be selected from any one or more of methyl formate, ethyl formate, propyl formate, butyl formate, isobutyl formate, pentyl formate, methyl acetate, ethyl acetate, allyl acetate, butyl acetate, isobutyl acetate, sec-butyl acetate, pentyl acetate, isoamyl acetate, hexyl acetate, methyl propionate, ethyl propionate, butyl propionate, methyl butyrate, ethyl butyrate, butyl butyrate, isobutyl butyrate, isoamyl butyrate, isoamyl isovalerate, methyl benzoate, ethyl benzoate, propyl benzoate, butyl benzoate, isoamyl benzoate, methyl phenylacetate, and ethyl phenylacetate. Preferably, the organic solvent is selected from any one or more of isoamyl acetate, ethyl acetate, and propyl acetate, which are relatively inexpensive and easy to obtain, and have good solubility for the raw materials, which is beneficial to improving the quality of the polymerization product.

[0048] Exemplarily, the alkane can be selected from any one or more of straight-chain or branched liquid alkanes having 5 to 16 carbon atoms, such as propane, n-butane, isobutane, pentane, isopentane, n-hexane, isohexane, cyclohexane, n-heptane, n-octane, and isooctane;

[0049] Exemplarily, the aromatic hydrocarbons include, but are not limited to, any one or more of benzene, toluene, xylene, chlorobenzene, and bromobenzene.

[0050] Preferably, the proportion of maleic anhydride in the organic solvent is 5% wt. to 25% wt.

[0051] In some embodiments of the present application, the polymerization reaction is carried out in an inert gas atmosphere. In some embodiments of the present application, the temperature of the polymerization reaction is 60°C to 100°C, the pressure is 0.2 MPa to 1.0 MPa, and the reaction time is 5 to 10 h.

[0052] In order to further increase the yield of the mixed C4-maleic anhydride polymer and the utilization rate of mixed C4, in some embodiments of the present application, step S2 includes: step S21, mixing the C4 mixed enrichment material, maleic anhydride, initiator, and organic solvent for a polymerization reaction to obtain a polymerization reaction product system; step S22, performing gas-liquid separation on the polymerization reaction product system to obtain a gas-phase product and a liquid-solid mixture; preferably, returning the gas-phase product to step S1 for isomerization reaction; step S23, performing liquid-solid separation on the liquid-solid mixture to obtain a solid-phase product and a liquid-phase product, and the solid-phase product is washed and dried to obtain the mixed C4-maleic anhydride polymer; preferably, returning the liquid-phase product to step S21 for polymerization reaction. By recycling the gas-phase product and the liquid-phase product in the polymerization reaction product system for isomerization reaction and polymerization reaction again, the yield of the mixed C4-maleic anhydride polymer can be significantly increased. The step of performing the isomerization reaction again on the above gas-phase product can be repeated one to multiple times.

[0053] In some embodiments of the present application, in the non-active C4 components obtained by performing multiple isomerization and polymerization reactions on the mixed C4 raw material, the content of terminal olefins is 1% to 3%, and the terminal olefins are n-butene and isobutene.

[0054] In some embodiments of the present application, the monomer conversion rate of the mixed C4 raw material can reach 25% to 50%, and the conversion rate of terminal olefins is 80% to 99%.

[0055] The above method of gas-liquid separation can be selected from the prior art. In some embodiments of the present application, flash separation is used for gas-liquid separation. Preferably, the conditions for the flash separation are that at a temperature of 20°C to 30°C, the gauge pressure of the system for the copolymerization reaction is reduced to atmospheric pressure to obtain a gas-phase product C containing mixed C4 and a liquid-solid mixture D containing the polymerization product.

[0056] The liquid-solid separation method in the above step S23 can be selected from the prior art. In some embodiments of the present application, the liquid-solid separation method is centrifugal separation. Preferably, the rotation speed of the centrifugal separation is 4000 - 8000 rpm, and the centrifugal separation time is 10 - 30 min, with better separation effect. Optionally, the centrifugal separator can be in any form of horizontal or vertical type.

[0057] Preferably, the above solid-phase product is washed with alcohols and / or alkanes. The alcohols include, but are not limited to, any one or more of ethanol, methanol, and isopropanol; the alkanes include, but are not limited to, any one or more of n-hexane, hexane, and cyclohexane.

[0058] In some embodiments of the present application, in step (3), the drying is drying by baking, and the drying temperature is 60 - 100 °C.

[0059] In some embodiments of the present application, after the polymer is dried, it is a powdery solid substance. The number-average particle size can be measured by scanning electron microscopy, and the number-average particle size of the particles is within 0.2 - 250 μm, preferably 0.2 - 2 μm.

[0060] In some embodiments of the present application, the molecular weight of the mixed C4-maleic anhydride polymer prepared by the above conversion method is 41000 - 70000, and the dispersion coefficient is less than or equal to 1.15.

[0061] In some typical embodiments of the present application, the conversion method of the mixed C4 is as Figure 1 shown, including:

[0062] (1) Concentration of active components in the mixed C4: The mixed C4 in the mixed C4 gas tank 1 is introduced into the fixed-bed reactor 2 filled with an acidic solid catalyst. Under the action of the catalyst, the n-butene in the mixed C4 undergoes an isomerization reaction to obtain a C4 mixed concentrated material A. The reaction temperature is controlled at 250 - 400 °C, the reaction pressure is from atmospheric pressure to 2 MPa, and the mixed feed space velocity is 0.1 - 2 h -1 . The product is taken at regular intervals, and its composition is analyzed by gas chromatography. The isobutene content in the C4 mixed concentrated material A can be increased to 20% - 40%.

[0063] (2) Polymerization reaction: Under a nitrogen atmosphere, the mixed solution B formed by an organic solvent dissolving maleic anhydride and an initiator is fed into the preheating tank 5 through a metering pump 4, and then into the polymerization reactor 6. At the same time, the generated C4 mixed concentrated material A is fed into the polymerization reactor 6 through a gas filtration tank 3 filled with a desiccant (such as molecular sieve, color-changing silica gel) to react with the mixed solution B after sufficient contact. The reaction temperature is 60°C - 100°C, the reaction pressure is 0.2 MPa - 1.0 MPa, and the reaction time is 5 - 10 h.

[0064] (3) Separation and purification: The mixed C4 product containing excessive unreacted substances obtained in step (2) enters the gas-liquid separator tank 7 for gas-liquid separation to obtain a gas-phase product C and a liquid-solid mixture D. The gas-phase product C returns to the inlet of the fixed-bed reactor 2 in step (1) for isomerization reaction again to increase the isobutene content in the mixed C4. The liquid-solid mixture D enters the liquid-solid separator 8 for liquid-solid separation. The obtained liquid E returns to the mixed solution B in step (2); the obtained solid is washed in the solid washing tank 9 in sequence and dried in the dryer 10 to obtain a polymer of mixed C4 - maleic anhydride. After cycling three times, the final polymerization product and the inactive C4 in the purified mixed C4 are obtained.

[0065] According to another typical embodiment of the present application, a mixed C4 - maleic anhydride polymer is provided, and the mixed C4 - maleic anhydride polymer is prepared by the conversion method of any of the above-mentioned mixed C4.

[0066] The mixed C4 - maleic anhydride polymer prepared by the above-mentioned conversion method of mixed C4, because the olefins in the mixed C4 are converted into isobutene through isomerization reaction during the preparation process, the content of isobutene in the mixed C4 is increased, and it is polymerized with maleic anhydride to generate a mixed C4 - maleic anhydride polymer with relatively stable molecular weight and particle size, improving its application value. On the other hand, while obtaining the mixed C4 - maleic anhydride polymer, the inactive C4 therein, that is, the alkane component, is recovered, further improving the additional value of the mixed C4.

[0067] In some typical embodiments of the present application, the molecular weight of the mixed C4 - maleic anhydride polymer is 41,000 - 70,000, and the dispersion coefficient is less than or equal to 1.15; preferably, the number-average particle size of the mixed C4 - maleic anhydride polymer is 0.2 - 2.0 μm.

[0068] The beneficial effects that can be achieved by the present application will be further described below in combination with examples and comparative examples.

[0069] Example 1

[0070] The preparation of the mixed C4 - maleic anhydride copolymer includes the following steps:

[0071] (1) After purging the fixed-bed reactor and the high-pressure autoclave with nitrogen. In the fixed-bed reactor, 20 g of the above-mentioned ZSM-35 catalyst particles were filled into the middle of the reaction tube; the reaction material, mixed C4 (propane 0.29%, propylene 0.07%, n-butane 38.9%, isobutane 8.99%, trans-butene 14.10%, n-butene 11.97%, isobutene 15.44%, cis-butene 9.72%, C5 0.52%) entered from the inlet of the reactor and contacted with the catalyst bed to undergo the butene isomerization reaction. The process conditions for the reaction were a reaction temperature of 250 °C, a pressure of atmospheric pressure, and WHSV (space velocity) = 0.1 h -1 , and a mixed C4 gas A1 was obtained, in which the content of isobutene was 25%.

[0072] (2) 90 g of the mixed C4 gas A1 prepared in step (1) was introduced into the high-pressure autoclave. 2.25 g of azobisisobutyronitrile and 45 g of maleic anhydride were dissolved in 1 L of isopropyl acetate solution to obtain a maleic anhydride solution containing an initiator (organic solution B1). This solution B1 was metered by a metering pump and then entered the high-pressure autoclave through the inlet of the high-pressure autoclave, and was fully mixed with the mixed C4 gas A1 to carry out a free radical copolymerization reaction. The copolymerization reaction pressure was 0.2 MPa, the copolymerization reaction temperature was 60 °C, and the copolymerization reaction time was 10 h.

[0073] (3) The product obtained in step (2) was introduced into a gas-liquid separator tank for gas-liquid separation. Gas-liquid separation was carried out at 20 °C to obtain a gas-phase product C1 and a liquid-solid mixture D1. The gas-phase product C was returned to the inlet of the fixed-bed reactor in step (1) for isomerization reaction again; the liquid-solid mixture D1 was subjected to liquid-solid separation at 4000 rpm for 15 min, and the obtained liquid E1 was returned to the organic solvent in step (2). The polymerization reaction was continued, and this step was repeated three times.

[0074] The solids obtained from multiple copolymerizations were combined, washed with absolute ethanol, and dried at 70 °C to obtain a mixed C4-maleic anhydride copolymer. The mass of the copolymer obtained was 63.2 g, the monomer conversion rate was 46.81%, and the conversion rate calculated based on the content of terminal olefins in the monomer was 91.07%. The molecular weight measured by a gel permeation chromatograph was 56000, the number average particle size of the polymer particles measured by a scanning electron microscope was 1.27 μm, the microsphere particle size dispersion coefficient was 1.051, and the content of terminal olefins in the gas separated in the last separation was 2.8%.

[0075] Example 2

[0076] The preparation of the mixed C4-maleic anhydride copolymer includes the following steps:

[0077] (1) After purging the fixed-bed reactor and the high-pressure autoclave with nitrogen. In the fixed-bed reactor, 20 g of the above-mentioned ZSM-35 catalyst particles were loaded into the middle of the reaction tube; the reaction material, mixed C4 (propane 0.29%, propylene 0.07%, n-butane 38.9%, isobutane 8.99%, trans-butene 14.10%, n-butene 11.97%, isobutene 15.44%, cis-butene 9.72%, C5 0.52%) entered from the inlet of the reactor and contacted with the catalyst bed to undergo butene isomerization reaction. The process conditions for the reaction were a reaction temperature of 250 °C, a pressure of atmospheric pressure, and WHSV = 0.1 h -1 , and a mixed C4 gas A2 was obtained, in which the isobutene content was 25%.

[0078] (2) 90 g of the mixed C4 gas A1 prepared in step (1) was introduced into the high-pressure autoclave. 2.25 g of benzoyl peroxide and 45 g of maleic anhydride were dissolved in 1 L of isopentyl acetate solution to obtain a maleic anhydride solution containing an initiator (organic solution B2). This solution B2 was metered by a metering pump and then entered the high-pressure autoclave through the inlet of the high-pressure autoclave, and was fully mixed with the mixed C4 gas A2 to carry out a free radical copolymerization reaction. The copolymerization reaction pressure was 0.2 MPa, the copolymerization reaction temperature was 60 °C, and the copolymerization reaction time was 8 h.

[0079] The subsequent steps were the same as (3) in Example 1. The solids obtained from multiple copolymerizations were combined and washed with absolute ethanol and dried at 70 °C to obtain a mixed C4 - maleic anhydride copolymer. The mass of the copolymer obtained was 64.33 g, the monomer conversion rate was 47.65%, and the conversion rate calculated based on the content of terminal olefins in the monomers was 92.7%. The molecular weight measured by a gel permeation chromatograph was 63,000, the number average particle size of the polymer particles measured by a scanning electron microscope was 1.83 μm, the microsphere particle size dispersion coefficient was 1.142, and the content of terminal olefins in the gas separated in the last time was 2.3%.

[0080] Example 3

[0081] The preparation of the mixed C4 - maleic anhydride copolymer includes the following steps:

[0082] (1) After purging the fixed-bed reactor and the high-pressure autoclave with nitrogen. In the fixed-bed reactor, 20 g of the above-mentioned ZSM-35 catalyst particles were loaded into the middle of the reaction tube; the reaction material, mixed C4 (propane 0.24%, propylene 0.03%, n-butane 36.12%, isobutane 8.99%, trans-butene 11.98%, n-butene 15.78%, isobutene 17.58%, cis-butene 10.21%, C5 0.63%) entered from the inlet of the reactor and contacted with the catalyst bed to undergo butene isomerization reaction. The process conditions for the reaction were a reaction temperature of 300 °C, a pressure of atmospheric pressure, and WHSV = 1 h -1, a mixed C4 gas A3 is obtained, wherein the isobutene content is 29%.

[0083] (2) The 120 g of the mixed C4 gas A3 prepared in step (1) is introduced into a high-pressure reactor. 2.25 g of azobisisobutyronitrile and 45 g of maleic anhydride are dissolved in 1 L of isopentyl acetate solution to obtain a maleic anhydride solution containing an initiator (organic solution B3). This solution B3 is metered by a metering pump and enters the high-pressure reactor through the inlet of the high-pressure reactor, and is sufficiently mixed with the mixed C4 gas A3 to carry out a free radical copolymerization reaction. The copolymerization reaction pressure is 0.2 MPa, the copolymerization reaction temperature is 60 °C, and the copolymerization reaction time is 6 h.

[0084] The subsequent steps are the same as those in (3) of Example 1. The solids obtained from multiple copolymerizations are combined and washed with absolute ethanol and dried at 70 °C to obtain a mixed C4-maleic anhydride copolymer. The mass of the copolymer obtained is 73.92 g, the monomer conversion rate is 44.80%, and the conversion rate calculated based on the content of terminal olefins in the monomer is 95.35%. The molecular weight measured by a gel permeation chromatograph is 46,000, the number average particle size of the polymer particles measured by a scanning electron microscope is 0.87 μm, the microsphere particle size dispersion coefficient is 1.017, and the content of terminal olefins in the gas separated for the last time is 1.7%.

[0085] Example 4

[0086] The preparation of the mixed C4-maleic anhydride copolymer includes the following steps:

[0087] (1) After purging the fixed-bed reactor and the high-pressure reactor with nitrogen. In the fixed-bed reactor, 20 g of the above-mentioned ZSM-35 catalyst particles are filled into the middle of the reaction tube; the reaction material mixed C4 (n-butane 4.731%, isobutane 41.323%, trans-butene 8.07%, n-butene 23.105%, isobutene 17.515%, cis-butene 4.212%, C5 1.024%) enters from the inlet of the reactor and contacts the catalyst bed to undergo a butene isomerization reaction. The process conditions for the reaction are a reaction temperature of 330 °C, a pressure of atmospheric pressure, and WHSV = 2 h -1 , a mixed C4 gas A4 is obtained, wherein the isobutene content is 34%.

[0088] In step (2), 190 g of the mixed C4 gas A4 prepared in step (1) was introduced into the high-pressure reactor. The subsequent steps were the same as those in (2) and (3) of Example 3. The solids obtained from multiple copolymerizations were combined, washed with absolute ethanol, and dried at 70 °C to obtain a mixed C4-maleic anhydride copolymer. The mass of the copolymer obtained was 120.18 g, the monomer conversion rate was 51.14%, and the conversion rate calculated based on the content of terminal olefins in the monomer was 98.37%. The molecular weight measured by a gel permeation chromatograph was 48,000, the number-average particle size of the polymer particles measured by a scanning electron microscope was 0.83 μm, the particle size dispersion coefficient of the microspheres was 1.006, and the content of terminal olefins in the gas separated in the last time was 1.1%.

[0089] Example 5

[0090] The preparation of the mixed C4-maleic anhydride copolymer includes the following steps:

[0091] (1) After purging the fixed-bed reactor and the high-pressure reactor with nitrogen. In the fixed-bed reactor, 20 g of the above ZSM-35 catalyst particles were loaded into the middle of the reaction tube; the reaction material, mixed C4 (propane 0.24%, propylene 0.03%, n-butane 36.12%, isobutane 8.99%, trans-butene 11.98%, n-butene 15.78%, isobutene 17.58%, cis-butene 10.21%, C5 0.63%) entered from the inlet of the reactor and contacted with the catalyst bed to undergo a butene isomerization reaction. The process conditions for the reaction were a reaction temperature of 400 °C, a pressure of atmospheric pressure, and WHSV = 2 h -1 , and a mixed C4 gas A5 was obtained, in which the isobutene content was 26%.

[0092] In step (2), 120 g of the mixed C4 gas A5 prepared in step (1) was introduced into the high-pressure reactor. The subsequent steps were the same as those in (2) and (3) of Example 3. The solids obtained from multiple copolymerizations were combined, washed with absolute ethanol, and dried at 70 °C to obtain a mixed C4-maleic anhydride copolymer. The mass of the copolymer obtained was 77.03 g, the monomer conversion rate was 46.69%, and the conversion rate calculated based on the content of terminal olefins in the monomer was 93.23%. The molecular weight measured by a gel permeation chromatograph was 46,000, the number-average particle size of the polymer particles measured by a scanning electron microscope was 0.71 μm, the particle size dispersion coefficient of the microspheres was 1.021, and the content of terminal olefins in the gas separated in the last time was 3%.

[0093] Example 6

[0094] The preparation of the mixed C4-maleic anhydride copolymer includes the following steps:

[0095] (1) After purging the fixed-bed reactor and the high-pressure autoclave with nitrogen. In the fixed-bed reactor, 20 g of the above-mentioned ZSM-35 catalyst particles were filled into the middle of the reaction tube; the reaction material, mixed C4 (propane 0.24%, propylene 0.03%, n-butane 36.12%, isobutane 8.99%, trans-butene 11.98%, n-butene 15.78%, isobutene 17.58%, cis-butene 10.21%, C5 0.63%) entered from the inlet of the reactor, contacted with the catalyst bed to undergo butene isomerization reaction, and the process conditions of the reaction were reaction temperature of 350 °C, pressure of atmospheric pressure, WHSV = 2 h -1 , and the mixed C4 gas A6 (isobutene content 31%) was obtained.

[0096] (2) 90 g of the mixed C4 gas A6 prepared in step (1) was introduced into the high-pressure autoclave. 2.25 g of azobisisobutyronitrile and 45 g of maleic anhydride were dissolved in 1 L of isopentyl acetate + n-hexane (volume ratio: 3:1) solution to obtain a maleic anhydride solution containing an initiator (organic solution B6). This solution B6 was metered by a metering pump and then entered the high-pressure autoclave through the inlet of the high-pressure autoclave, and was fully mixed with the mixed C4 gas A6 to carry out a free radical copolymerization reaction. The copolymerization reaction pressure was 0.2 MPa, the copolymerization reaction temperature was 70 °C, and the copolymerization reaction time was 8 h.

[0097] The subsequent steps were the same as those in (3) of Example 1. The solids obtained by multiple copolymerizations were combined, washed with anhydrous ethanol, and dried at 70 °C to obtain a mixed C4-maleic anhydride copolymer. The mass of the copolymer obtained was 73.5 g, the monomer conversion rate was 54.45%, and the conversion rate calculated based on the content of terminal olefins in the monomers was 97.98%. The molecular weight measured by gel permeation chromatography was 68000, the number average particle size of the polymer particles measured by scanning electron microscopy was 0.77 μm, the microsphere particle size dispersion coefficient was 1.026, and the content of terminal olefins in the gas separated in the last time was 1%.

[0098] Example 7

[0099] The preparation of the mixed C4-maleic anhydride copolymer includes the following steps:

[0100] (1) After purging the fixed-bed reactor and the high-pressure autoclave with nitrogen. In the fixed-bed reactor, 20 g of the above-mentioned ZSM-35 catalyst particles were filled into the middle of the reaction tube; the reaction material, mixed C4 (propane 0.29%, propylene 0.07%, n-butane 38.9%, isobutane 8.99%, trans-butene 14.10%, n-butene 11.97%, isobutene 15.44%, cis-butene 9.72%, C5 0.52%) entered from the inlet of the reactor, contacted with the catalyst bed to undergo butene isomerization reaction, and the process conditions of the reaction were reaction temperature of 380 °C, pressure of atmospheric pressure, WHSV = 1 h -1, a mixed C4 gas A7 (isobutene content 24%) is obtained.

[0101] (2) 225 g of the mixed C4 gas A7 prepared in step (1) is introduced into a high-pressure reactor. 9 g of azobisisobutyronitrile and 45 g of maleic anhydride are dissolved in 1 L of isopentyl acetate + n-hexane (volume ratio: 3:1) solution to obtain a maleic anhydride solution containing an initiator (organic solution B7). This solution B7 is metered by a metering pump and enters the high-pressure reactor through the inlet of the high-pressure reactor, and is fully mixed with the mixed C4 gas A7 for a free radical copolymerization reaction. The copolymerization reaction pressure is 1.0 MPa, the copolymerization reaction temperature is 70 °C, and the copolymerization reaction time is 6 h.

[0102] The subsequent steps are the same as those in (3) of Example 1. The solids obtained from multiple copolymerizations are combined and washed with absolute ethanol and dried at 70 °C to obtain a mixed C4-maleic anhydride copolymer. The mass of the copolymer obtained is 99.13 g, the monomer conversion rate is 36.71%, and the conversion rate calculated based on the content of terminal olefins in the monomers is 92.93%. The molecular weight measured by a gel permeation chromatograph is 64000, the number average particle size of the polymer particles measured by a scanning electron microscope is 0.92 μm, the microsphere particle size dispersion coefficient is 1.023, and the content of terminal olefins in the gas separated in the last time is 2.6%.

[0103] Example 8

[0104] The preparation of the mixed C4-maleic anhydride copolymer includes the following steps:

[0105] (1) After purging the fixed-bed reactor and the high-pressure reactor with nitrogen. In the fixed-bed reactor, 20 g of the above-mentioned ZSM-35 catalyst particles are filled into the middle of the reaction tube; the reaction material mixed C4 (propane 0.24%, propylene 0.03%, n-butane 36.12%, isobutane 8.99%, trans-butene 11.98%, n-butene 15.78%, isobutene 17.58%, cis-butene 10.21%, C5 0.63%) enters from the inlet of the reactor and contacts the catalyst bed for a butene isomerization reaction. The process conditions for the reaction are a reaction temperature of 350 °C, a pressure of atmospheric pressure, and WHSV = 1 h -1 , a mixed C4 gas A8 (isobutene content 27%) is obtained.

[0106] (2) 360 g of the mixed C4 gas A8 prepared in step (1) is introduced into a high-pressure reactor. 18 g of azobisisobutyronitrile and 45 g of maleic anhydride are dissolved in 1 L of propyl acetate solution to obtain a maleic anhydride solution containing an initiator (organic solution B8). This solution B8 is metered by a metering pump and enters the high-pressure reactor through the inlet of the high-pressure reactor, and is fully mixed with the mixed C4 gas A8 for a free radical copolymerization reaction. The copolymerization reaction pressure is 0.2 MPa, the copolymerization reaction temperature is 70 °C, and the copolymerization reaction time is 8 h.

[0107] The subsequent steps are the same as those in (3) of Example 1. The solids obtained from multiple copolymerizations are combined, washed with petroleum ether, and dried at 70 °C to obtain a mixed C4-maleic anhydride copolymer. The mass of the copolymer obtained is 118.31 g, the monomer conversion rate is 29.21%, and the conversion rate calculated based on the content of terminal olefins in the monomers is 83.12%. The molecular weight measured by a gel permeation chromatograph is 68,000, the number-average particle size of the polymer particles measured by a scanning electron microscope is 1.26 μm, the particle size dispersion coefficient of the microspheres is 1.012, and the content of terminal olefins in the gas separated in the last time is 1%.

[0108] Example 9

[0109] The preparation of the mixed C4-maleic anhydride copolymer comprises the following steps:

[0110] (1) After purging the fixed-bed reactor and the high-pressure autoclave with nitrogen. In the fixed-bed reactor, 20 g of the above-mentioned ZSM-35 catalyst particles are filled into the middle of the reaction tube; the reaction material, mixed C4 (propane 0.24%, propylene 0.03%, n-butane 36.12%, isobutane 8.99%, trans-butene 11.98%, n-butene 15.78%, isobutene 17.58%, cis-butene 10.21%, C5 0.63%) enters from the inlet of the reactor and contacts with the catalyst bed to carry out the butene isomerization reaction, wherein the process conditions of the reaction are a reaction temperature of 350 °C, a pressure of atmospheric pressure, and WHSV = 1 h -1 , to obtain a mixed C4 gas A9 (isobutene content 27%).

[0111] (2) 360 g of the mixed C4 gas A9 prepared in step (1) is introduced into the high-pressure autoclave. 18 g of azobisisobutyronitrile and 45 g of maleic anhydride are dissolved in 1 L of propyl acetate solution to obtain a maleic anhydride solution containing an initiator (organic solution B9). This solution B9 is metered by a metering pump and enters the high-pressure autoclave through the inlet of the high-pressure autoclave, and is fully mixed with the mixed C4 gas A9 to carry out a free radical copolymerization reaction. The copolymerization reaction pressure is 0.2 MPa, the copolymerization reaction temperature is 70 °C, and the copolymerization reaction time is 5 h.

[0112] The subsequent steps are the same as those in (3) of Example 1. The solids obtained from multiple copolymerizations are combined, washed with petroleum ether, and dried at 70 °C to obtain a mixed C4-maleic anhydride copolymer. The mass of the copolymer obtained is 131.91 g, the monomer conversion rate is 32.57%, and the conversion rate calculated based on the content of terminal olefins in the monomers is 91.81%. The molecular weight measured by a gel permeation chromatograph is 58,000, the number-average particle size of the polymer particles measured by a scanning electron microscope is 1.01 μm, the particle size dispersion coefficient of the microspheres is 1.068, and the content of terminal olefins in the gas separated in the last time is 3%.

[0113] Example 10

[0114] The preparation of the mixed C4-maleic anhydride copolymer comprises the following steps:

[0115] (1) After purging the fixed-bed reactor and the high-pressure autoclave with nitrogen. In the fixed-bed reactor, 20 g of the above-mentioned SAPO-11 catalyst particles are filled into the middle of the reaction tube; the reaction material, mixed C4 (propane 0.29%, propylene 0.07%, n-butane 38.9%, isobutane 8.99%, trans-butene 14.10%, n-butene 11.97%, isobutene 15.44%, cis-butene 9.72%, C5 0.52%) enters from the inlet of the reactor and contacts with the catalyst bed to carry out the butene isomerization reaction. The process conditions for the reaction are a reaction temperature of 380 °C, a pressure of atmospheric pressure, and WHSV = 2 h -1 , and the mixed C4 gas A10 (isobutene content 23%) is obtained.

[0116] (2) 90 g of the mixed C4 gas A10 prepared in step (1) is introduced into the high-pressure autoclave. 13.5 g of azobisisobutyronitrile and 45 g of maleic anhydride are dissolved in 1 L of propyl acetate solution to obtain a maleic anhydride solution containing an initiator (organic solution B10). This solution B10 is metered by a metering pump and then enters the high-pressure autoclave through the inlet of the high-pressure autoclave, and is fully mixed with the mixed C4 gas A10 to carry out a free radical copolymerization reaction. The copolymerization reaction pressure is 0.2 MPa, the copolymerization reaction temperature is 60 °C, and the copolymerization reaction time is 5 h.

[0117] The subsequent steps are the same as those in (3) of Example 1. The solids obtained from multiple copolymerizations are combined and washed with n-hexane and dried at 70 °C to obtain the mixed C4-maleic anhydride copolymer. The mass of the copolymer obtained is 64.94 g, the monomer conversion rate is 48.1%, and the conversion rate calculated based on the content of terminal olefins in the monomer is 93.21%. The molecular weight measured by a gel permeation chromatograph is 54000, the number average particle size of the polymer particles measured by a scanning electron microscope is 0.27 μm, the microsphere particle size dispersion coefficient is 1.017, and the content of terminal olefins in the gas separated in the last time is 2.5%.

[0118] Example 11

[0119] The preparation of the mixed C4-maleic anhydride copolymer comprises the following steps:

[0120] (1) After purging the fixed-bed reactor and the high-pressure autoclave with nitrogen. In the fixed-bed reactor, 20 g of the above-mentioned SAPO-11 catalyst particles were loaded into the middle of the reaction tube; the reaction material, mixed C4 (propane 0.29%, propylene 0.07%, n-butane 38.9%, isobutane 8.99%, trans-butene 14.10%, n-butene 11.97%, isobutene 15.44%, cis-butene 9.72%, C5 0.52%) entered from the inlet of the reactor, contacted with the catalyst bed to undergo butene isomerization reaction, and the process conditions of the reaction were reaction temperature of 380 °C, pressure of atmospheric pressure, WHSV = 2 h -1 , and mixed C4 gas A11 (isobutene content 23%) was obtained.

[0121] (2) 450 g of the mixed C4 gas A11 prepared in step (1) was introduced into the high-pressure autoclave. 13.5 g of azobisisobutyronitrile and 180 g of maleic anhydride were dissolved in 1 L of propyl acetate solution to obtain a maleic anhydride solution containing initiator (organic solution B11). This solution B11 was metered by a metering pump and then entered the high-pressure autoclave through the inlet of the high-pressure autoclave, and was fully mixed with the mixed C4 gas A11 to carry out a free radical copolymerization reaction. The copolymerization reaction pressure was 0.5 MPa, the copolymerization reaction temperature was 60 °C, and the copolymerization reaction time was 5 h.

[0122] The subsequent steps were the same as (3) in Example 1. The solids obtained from multiple copolymerizations were combined, washed with n-hexane, and dried at 70 °C to obtain a mixed C4-maleic anhydride copolymer. The mass of the copolymer obtained was 285.26 g, the monomer conversion rate was 45.28%, and the conversion rate calculated based on the content of terminal olefins in the monomers was 94.04%. The molecular weight measured by gel permeation chromatography was 51,000, the number average particle size of the polymer particles measured by scanning electron microscopy was 0.23 μm, the microsphere particle size dispersion coefficient was 1.087, and the content of terminal olefins in the gas separated in the last time was 2.2%.

[0123] Example 12

[0124] (1) After purging the fixed-bed reactor and the high-pressure autoclave with nitrogen. In the fixed-bed reactor, 20 g of the above-mentioned SAPO-11 catalyst particles were loaded into the middle of the reaction tube; the reaction material, mixed C4 (propane 0.29%, propylene 0.07%, n-butane 38.9%, isobutane 8.99%, trans-butene 14.10%, n-butene 11.97%, isobutene 15.44%, cis-butene 9.72%, C5 0.52%) entered from the inlet of the reactor, contacted with the catalyst bed to undergo butene isomerization reaction, and the process conditions of the reaction were reaction temperature of 380 °C, pressure of atmospheric pressure, WHSV = 2 h -1 , and mixed C4 gas A12 (isobutene content 23%) was obtained.

[0125] (2) Feed 450 g of the mixed C4 gas A12 prepared in step (1) into a high-pressure reactor. Dissolve 13.5 g of azobisisobutyronitrile and 90 g of maleic anhydride in 1 L of butyl acetate solution to obtain a maleic anhydride solution containing an initiator (organic solution B12). This solution B12 is metered by a metering pump and enters the high-pressure reactor through the inlet of the high-pressure reactor, where it is fully mixed with the mixed C4 gas A12 for free radical copolymerization reaction. The copolymerization reaction pressure is 1 MPa, the copolymerization reaction temperature is 60 °C, and the copolymerization reaction time is 6 h.

[0126] The subsequent steps are the same as (3) in Example 1. The solids obtained from multiple copolymerizations are combined, washed with n-hexane, and dried at 70 °C to obtain a mixed C4-maleic anhydride copolymer. The mass of the copolymer obtained is 197.66 g, the monomer conversion rate is 36.6%, and the conversion rate calculated based on the content of terminal olefins in the monomer is 92.65%. The molecular weight measured by a gel permeation chromatograph is 41000, the number average particle size of the polymer particles measured by a scanning electron microscope is 0.28 μm, the microsphere particle size dispersion coefficient is 1.053, and the content of terminal olefins in the gas separated in the last separation is 2.7%.

[0127] Example 13

[0128] The difference from Example 1 is that in step (3), the separated gas phase product C1 and liquid E1 are not reused, and the treatment method of the obtained solid is the same as that in Example 1. The mass of the copolymer obtained is 40.57 g, the monomer conversion rate is 30.05%, and the conversion rate calculated based on the content of terminal olefins in the monomer is 58.46%. The molecular weight measured by a gel permeation chromatograph is 41000, the number average particle size of the polymer particles measured by a scanning electron microscope is 0.76 μm, the microsphere particle size dispersion coefficient is 1.023, and the content of terminal olefins in the separated gas is 13.38%.

[0129] Example 14

[0130] The difference from Example 1 is that in step (3), the separated gas phase product C1 and liquid E1 are reused again, that is, steps (1) to (3) are repeated twice, and the treatment method of the obtained solid is the same as that in Example 1. The mass of the copolymer obtained is 55.99 g, the monomer conversion rate is 41.48%, and the conversion rate calculated based on the content of terminal olefins in the monomer is 80.69%. The molecular weight measured by a gel permeation chromatograph is 47000, the number average particle size of the polymer particles measured by a scanning electron microscope is 0.85 μm, the microsphere particle size dispersion coefficient is 1.041, and the content of terminal olefins in the gas separated in the last separation is 6.7%.

[0131] Example 15

[0132] It is only different from Example 1 in that in step (1), the reaction pressure is 2 MPa, and the obtained mixed C4 gas A15 (isobutene content 20%) is obtained.

[0133] The mass of the obtained copolymer is 63.96 g, the monomer conversion rate is 47.38%, and the conversion rate calculated according to the content of terminal olefins in the monomer is 91.81%. The molecular weight measured by a gel chromatograph is 51,000, the number-average particle size of the polymer particles measured by a scanning electron microscope is 1.01 μm, the particle size dispersion coefficient of the microspheres is 1.053, and the content of terminal olefins in the gas separated for the last time is 3%.

[0134] Example 16

[0135] It is only different from Example 1 in that in step (1), the reaction pressure is 1 MPa, and the obtained mixed C4 gas A16 (isobutene content 23%) is obtained.

[0136] The mass of the obtained copolymer is 64.93 g, the monomer conversion rate is 48.10%, and the conversion rate calculated according to the content of terminal olefins in the monomer is 93.20%. The molecular weight measured by a gel chromatograph is 57,000, the number-average particle size of the polymer particles measured by a scanning electron microscope is 1.14 μm, the particle size dispersion coefficient of the microspheres is 1.011, and the content of terminal olefins in the gas separated for the last time is 2.5%.

[0137] Comparative Example 1

[0138] It is different from Example 1 in that the treatment in step (1) is not carried out, and the same mixed C4 raw material (90 g) as in Example 1 is introduced into a high-pressure reaction kettle, and the treatments in steps (2) and (3) are carried out.

[0139] The mass of the obtained copolymer is 20.3 g, the monomer conversion rate is 14.83%, and the conversion rate calculated according to the content of terminal olefins in the monomer is 29.25%. The molecular weight measured by a gel chromatograph is 53,000, the number-average particle size of the polymer particles measured by a scanning electron microscope is 1.34 μm, the particle size dispersion coefficient of the microspheres is 1.121, and the content of terminal olefins in the separated gas is 19.18%.

[0140] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects: the above conversion method of mixed C4 converts the olefins in the mixed C4 into isobutene through isomerization reaction, increases the content of isobutene in the mixed C4, and polymerizes it with maleic anhydride to generate a mixed C4-maleic anhydride polymer with relatively uniform molecular weight and particle size distribution, improving its application value. On the other hand, while obtaining the mixed C4-maleic anhydride polymer, the non-active C4, that is, the alkane component, is recovered, further improving the added value of the mixed C4.

[0141] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A mixed C4 conversion method, characterized in that: include: Step S1, under the action of a catalyst, isomerize the n-butene in the mixed C4 to convert it into isobutene, thereby obtaining a C4 mixed enriched material; Step S2, mixing the C4 mixed concentrated material, maleic anhydride, initiator and organic solvent, and performing polymerization reaction to obtain mixed C4-maleic anhydride polymer and inactive C4.

2. The conversion method according to claim 1, characterized in that The catalyst is an acidic solid catalyst. Preferably, the catalyst is any one or more of ZSM-22, ZSM-23, SAPO-11, MeAPO-11, Fe-ZSM-5 and ZSM-35. More preferably, the feed space velocity of the mixed C4 is 0.1 to 2 h -1 ; And / or, the temperature of the isomerization reaction is 250-400° C. and the pressure is 0-2 MPa.

3. The conversion method according to claim 1, characterized in that The molar ratio of isobutylene to normal butene in the C4 mixed enriched material is 5 to 20:1; Preferably, the content of isobutylene in the C4 mixed enriched material is 20% to 40%; Preferably, the step S1 comprises: isomerizing the n-butene in the mixed C4 to convert it into isobutene under the action of a catalyst, performing gas-liquid separation on the isomerized product, and collecting the gas phase as the C4 mixed concentrated material; Preferably, the gas-liquid separation is carried out in a condensation tank, and the temperature of the condensation tank is 25-35°C.

4. The conversion method according to claim 1, characterized in that The mass ratio of the C4 mixed concentrated material to maleic anhydride is 0.5 to 20:1, preferably 2 to 10:1; Preferably, the C4 mixed concentrated material is subjected to a water removal treatment before the mixing.

5. The conversion method according to claim 1, characterized in that The initiator is a thermal decomposition type initiator. Preferably, the initiator is selected from at least one or more of dibenzoyl peroxide, diisopropyl peroxide, di-tert-butyl peroxide, dodecyl peroxide, tert-butyl perbenzoate, diisopropyl peroxydicarbonate, dicarbonyl peroxide, azobisisobutyronitrile and azobisisoheptylonitrile; preferably, the mass ratio of the initiator to the maleic anhydride is 0.01-0.20:1; And / or, the organic solvent comprises at least one of organic acid alkyl esters, alkanes and aromatic hydrocarbons; preferably, the organic solvent is selected from any one or more of isoamyl acetate, ethyl acetate and propyl acetate, and preferably, the proportion of maleic anhydride in the organic solvent is 5%wt. to 25%wt.

6. The conversion method according to claim 1, characterized in that The polymerization reaction is carried out in an inert gas atmosphere; And / or, the polymerization reaction temperature is 60° C.-100° C., the pressure is 0.2 MPa-1.0 MPa, and the reaction time is 5-10 h.

7. The transformation method according to any one of claims 1 to 6, characterized in that The mixed C4 is a mixture containing C4 hydrocarbon compounds produced during the petroleum refining process; Preferably, the content of C4 olefins in the mixed C4 is 48% to 55%, and the content of alkanes in the mixed C4 is 45% to 50%.

8. The conversion method according to any one of claims 1 to 6, characterized in that The step S2 comprises: Step S21, mixing the C4 mixed concentrated material, maleic anhydride, an initiator and an organic solvent, and performing a polymerization reaction to obtain a polymerization reaction product system; Step S22, performing gas-liquid separation on the polymerization reaction product system to obtain a gas phase product and a liquid-solid mixture; preferably, the gas phase product is returned to the step S1 to perform the isomerization reaction; Step S23, performing liquid-solid separation on the liquid-solid mixture to obtain a solid phase product and a liquid phase product, and washing and drying the solid phase product to obtain the mixed C4-maleic anhydride polymer; preferably, returning the liquid phase product to the step S21 to perform the polymerization reaction; Optionally, the liquid-solid separation method is centrifugal separation, the rotation speed of the centrifugal separation is 4000-8000 rpm, and the time of the centrifugal separation is 10-30 min; Preferably, the washing is performed using alcohols and / or alkanes, wherein the alcohols include any one or more of ethanol, methanol and isopropanol; and the alkanes include any one or more of n-hexane, hexane and cyclohexane.

9. A mixed C4-maleic anhydride polymer, characterized in that: It is prepared by the mixed C4 conversion method described in any one of claims 1 to 8.

10. The mixed C4-maleic anhydride polymer according to claim 9, characterized in that: The molecular weight of the mixed C4-maleic anhydride polymer is 41000-70000, and the dispersion coefficient is less than or equal to 1.15; preferably, the number average particle size of the mixed C4-maleic anhydride polymer is 0.2-2.0 μm.

Images