A method for polymer demetallization

Abstract

The present invention provides a method for polymer demetallization. The method comprises the following steps: after mixing and reacting a polymer solution to be treated with a complexing agent and hydrazine hydrate, a mixed solution is obtained; separating the mixed solution through an adsorption column filled with an adsorbent, and the obtained filtrate is the demetallized polymer solution. The method of the present invention adopts a complexation reduction method, uses a dicarboxylic acid and its derivatives having a cis structure in the spatial configuration as the complexing agent, reacts with metal ions in the polymer solution to form metal complexes, uses hydrazine hydrate as a strong reducing agent to reduce metal ions such as aluminum and zirconium in the polymer solution into metal atoms, and then completes the removal of metal atoms through an adsorption column filled with an adsorbent to obtain the demetallized polymer solution. The method for polymer demetallization of the present invention has a remarkable effect on the removal of metals in the polymer, is simple to operate, has a low cost, and has broad industrialization prospects.

Description

Technical Field

[0001] The present invention relates to a method for polymer demetallization, belonging to the technical field of polymer demetallization. Background Art

[0002] As a functional polyolefin material, the copolymer of ethylene with α-olefin and cycloolefin has excellent mechanical strength, machining properties, and excellent chemical corrosion resistance. At the same time, its optical properties, gas barrier properties, chemical resistance, light resistance and other properties are excellent, and it plays an irreplaceable role in industry, agriculture, national defense, transportation and people's daily life, with broad application prospects.

[0003] At present, most in the industry use highly efficient metallocene olefin polymerization catalyst systems for the production of polyolefin products. Generally, metallocene catalysts contain elements in Groups IVB, VB, and VIB of the periodic table, especially vanadium, titanium, and zirconium. The cocatalysts mainly contain elements such as aluminum. These catalysts are usually called transition metal catalysts and have high olefin polymerization catalytic activity. However, once the polymerization is completed, the metals in the catalyst remain in the polyolefin product, which will have a negative impact on the appearance, dielectric properties, optical properties, medical material properties, etc. of the end product. Therefore, for polyolefin products, especially high-end polyolefin products such as medical grade and optical grade, how to efficiently remove metal residues (abbreviated as deashing) is of utmost importance.

[0004] The commonly used deashing methods in the polymer industrialization process mainly include aqueous phase extraction method, coagulation sedimentation method and complexation adsorption method. Among them, the complexation adsorption method is the most commonly used deashing method in polymer industrial production, and has the advantages of simple process, large adsorption capacity, high removal efficiency, few interference factors and good stability. Complexing agents are generally divided into inorganic and organic categories. Among them, inorganic complexing agents are usually easily decomposed at high temperatures and are only applicable to alkaline media, with limited application scope. Although organic complexing agents have a wider application range, it is usually difficult to reduce the metal content in the polymer solution to below 10 ppm. In addition, supported adsorbent fillers are often used for complexation deashing in the industrialization process. This type of adsorbent is a solid filler obtained by impregnating and calcining an alumina carrier and a complexing agent material, and the effective loading amount of the complexing agent is low, which is restricted to a certain extent in application.

[0005] US4992529A discloses a method for removing metals with a mixed acid. The characteristic of this method is that a monocarboxylic acid reacts with metals in the organic phase to form carboxylates insoluble in the organic phase. These carboxylates react with the inorganic acids in the mixed acid to form inorganic salts soluble in the aqueous phase, and the carboxylic acid is reduced and returns to the organic phase, then reacts with the metals in the polymer solution to form carboxylates, and so on in a cycle until all the metals in the polymer solution are transferred to the aqueous phase, thereby achieving the removal of metal residues. Here, the carboxylic acid acts as a phase transfer catalyst. The idea of this method is relatively novel, but the removal effect is not ideal, and a large amount of water is also required.

[0006] CN114534694A discloses a complexing adsorption filler, its preparation method and application. The adsorption filler is a molecular sieve filler loaded with a hydroxyquinoline compound, and an organic acid can be loaded on the molecular sieve loaded with the hydroxyquinoline compound. The adsorption filler can effectively remove the residual catalyst in the polyolefin solution, and has the advantages of fast deashing speed, large adsorption capacity, and low pressure drop, and is suitable for the removal of catalysts in a variety of olefin solution polymerization processes. However, the preparation process of the adsorption filler is complex and cumbersome, and the loading amount of hydroxyquinoline is relatively low, resulting in a low adsorption capacity of the adsorption filler and a high operating cost.

[0007] CN114989331A discloses a method for complex deashing of a polyolefin solution. The method includes the following steps: 1) adding diminazene to the polyolefin solution to perform complex adsorption on the metal ions in the solution to form a complex; 2) passing the polyolefin solution containing the complex through an adsorption column filled with a porous metal oxide for adsorption treatment to obtain a purified polyolefin solution. This deashing method can efficiently remove the residual metals in the polyolefin solution, has a simple process, low swelling of the filler, low system pressure drop, and a long service life of the deashing filler and a long replacement cycle of the adsorption column, and can significantly save the treatment cost. However, due to the general complexing ability of diminazene to metals, the metal removal rate is relatively low, especially the content of metal aluminum in the polymer is relatively high.

[0008] CN102875702A discloses a method for removing metals from a polymer. This method uses adding an organic base, such as n-butyllithium, phenyllithium, etc., to the glue solution, then adding an oxidant, washing with water after the reaction, and finally centrifuging to achieve the purpose of removing metal residues in the glue solution. Although this method has a relatively high efficiency in removing metal residues in the polymer, since organic bases are used, some metal ions are introduced, resulting in higher raw material input and the cost of removing residual catalysts, and the requirements for equipment by the externally added organic bases are high.

[0009] CN114392724A discloses a special deashing adsorbent for polyolefins, its preparation method and application. This deashing adsorbent is prepared by using pyridine-3-carboxylic acid as a complexing agent and loading it on an oxide carrier. This deashing adsorbent can efficiently remove residual metals in polyolefin solutions, significantly reduce the metal residues in polyolefin products, and has the advantages of fast deashing rate, large adsorption capacity, low swelling, and low solution pressure drop compared with traditional chelating adsorption methods. However, the preparation process of this deashing adsorbent is complex and cumbersome. At the same time, the loading amount of pyridine-3-carboxylic acid is relatively low, resulting in a low adsorption capacity of the adsorbent and a high operating cost.

[0010] CN113856637A discloses a method for removing metal residues in the production process of COC and COP by using a complexing adsorption filler. Compared with traditional adsorption resins, this adsorption filler has the advantages of fast metal deashing speed and large adsorption capacity, and there will be no swelling phenomenon at the same time. This adsorption filler is prepared by the following method: reacting silica solid, solvent, and phosphorus tribromide in proportion to prepare brominated silica solid, and then reacting it with an appropriate amount of diethyl iminodiacetate to obtain a yellow solid. After acidifying with hydrochloric acid, the adsorption filler is obtained. The preparation process of this adsorption filler is cumbersome and complex, and the heavy metal removal rate is not high.

[0011] US5073621A discloses a method for demetallization using water as a solubilizer. In this method, a dicarboxylic acid is first dissolved in water and then added to the latex, which can better remove metals in the latex. However, this method is prone to cause latex emulsification, which is not conducive to the reaction between the dicarboxylic acid and metal ions, affects the metal removal rate, and the process is difficult to control.

[0012] CN1067898A discloses a method for removing residual metal catalysts after polymer hydrogenation. In this method, hydrogen peroxide is added as an oxidant and sebacic acid is added as a precipitant to the hydrogenated butadiene-styrene random copolymer latex. Sebacic acid is dissolved in a diethylene glycol-butyl ether aqueous solution to form a sebacic acid solution, which greatly improves the metal removal effect in the latex. However, the positions of the two carboxyl groups of the dicarboxylic acid used in this method are not fixed, and the complexing effect on metals is poor, resulting in a low metal removal rate.

[0013] CN105624405B discloses a method for recovering catalyst metal ions from synthetic diamond wastewater. In this method, the synthetic diamond wastewater is filtered to obtain a filtrate, which is reacted with hydrazine hydrate under alkaline conditions to obtain a precipitate; the precipitate is filtered, washed with water, and dried under a reducing atmosphere to recover the catalyst metal powder. The metal ion recovery rate of this method reaches more than 95%, among which, C O 2+The recovery rate is close to 100%. However, the traditional hydrazine hydrate reduction process needs to be carried out under strong alkaline conditions. Under such conditions, metallic aluminum will form a gel-like white precipitate, aluminum hydroxide. Polymers are likely to deposit on its surface to form a coating layer, and then form oil-soluble microparticles, which exist in the polymer solution, preventing the reduction reaction between aluminum ions and hydrazine hydrate and making it impossible to achieve efficient removal of aluminum ions.

[0014] Existing polymer de-metallization technologies have deficiencies such as cumbersome adsorbent preparation processes, long de-metallization process flows, and relatively low removal efficiencies. Therefore, developing a new polymer de-metallization method has become one of the urgent problems to be solved in this field. Summary of the Invention

[0015] To solve the above technical problems, the purpose of the present invention is to provide a polymer de-metallization method. This method has the advantages of high de-metallization efficiency, simple process, and low cost.

[0016] To achieve the above purpose, the present invention provides a polymer de-metallization method, which includes the following steps:

[0017] (1) After mixing and reacting a polymer solution to be treated with a complexing agent and hydrazine hydrate, a mixed solution is obtained;

[0018] (2) Passing the mixed solution through an adsorption column filled with an adsorbent for separation, and the obtained filtrate is the de-metallized polymer solution;

[0019] Wherein, the complexing agent includes one or a combination of several of dicarboxylic acids and their derivatives. The dicarboxylic acid contains a carbon-carbon double bond, and the two carboxyl groups are arranged on the same side of the carbon-carbon double bond, and it has a cis structure in terms of spatial configuration.

[0020] The present invention provides a method for removing metals from polymers, especially a method for removing residual metals of catalysts in polymers (mainly polyolefins). This method uses a dicarboxylic acid and its derivatives with a cis structure in the spatial configuration as metal complexing reagents. After reacting with metal ions in the polymer solution, this kind of dicarboxylic acid and its derivatives with a cis structure form metal complexes, especially forming a complex reaction with aluminum ions in the polymer solution to generate water-soluble aluminum ion complexes. Then, using hydrazine hydrate as a strong reducing reagent, metal ions such as zirconium and aluminum in the polymer solution are reduced to metal atoms, and then the metal atoms are filtered and removed through an adsorption column filled with an adsorbent, and the obtained filtrate is the polymer solution after metal removal. In the absence of a complexing agent, aluminum ions will form a gel-like aluminum hydroxide precipitate under the alkaline conditions during the reduction by hydrazine hydrate. This precipitate will be further coated by the polymer to form oil-soluble fine particles existing in the polymer solution, preventing the aluminum ions from reacting with hydrazine hydrate, resulting in the difficulty of filtering or adsorbing and removing aluminum ions in the subsequent process, and thus leading to a low removal rate of aluminum ions. However, the method of the present invention, by introducing an efficient complexing reagent, that is, a dicarboxylic acid and its derivatives with a cis structure in the spatial configuration, compared with traditional complexing reagents, the complexing agent of the present invention can quickly form stable metal ion complexes with aluminum ions, avoiding the formation of a gel-like white precipitate of aluminum hydroxide by metal aluminum ions under alkaline conditions, so significantly improving the removal efficiency of metal ions.

[0021] In the above method for removing metals from polymers, preferably, the dicarboxylic acid has the structure shown in the following formula I:

[0022]

[0023] In formula I, R1 and R2 are the same or different, and R1 and R2 each independently selected from an H atom, a straight-chain or branched-chain alkyl group having 1 to 10 carbon atoms; preferably, R1 and R2 are the same or different, and R1 and R2 each independently selected from an H atom, a straight-chain or branched-chain alkyl group having 1 to 5 carbon atoms.

[0024] In the above method for removing metals from polymers, preferably, the derivatives of the dicarboxylic acid include one or a combination of several of acid anhydrides, acyl halides, amides, esters, nitriles, etc. formed by the dicarboxylic acid. More preferably, the derivatives of the dicarboxylic acid include acid anhydrides of the dicarboxylic acid.

[0025] In the above method for removing metals from polymers, preferably, the acid anhydride of the dicarboxylic acid has the structure shown in the following formula II:

[0026]

[0027] In formula II, R1 and R2 are the same or different, and each of R1 and R2 independently selected from a hydrogen atom, a linear or branched alkyl group having 1 to 10 carbon atoms; preferably, R1 and R2 are the same or different, and each of R1 and R2 independently selected from a hydrogen atom, a linear or branched alkyl group having 1 to 5 carbon atoms.

[0028] In the above method for removing metal from a polymer, preferably, the dicarboxylic acid and its derivatives include maleic acid (i.e., maleic acid), maleic anhydride (i.e., maleic anhydride), cis-methyl maleic acid (i.e., 2-methyl maleic acid), cis-methyl maleic anhydride (i.e., 2-methyl maleic anhydride), 2,3-dimethyl maleic acid, and 2,3-dimethyl maleic anhydride, etc., or a combination of one or more thereof.

[0029] In some specific embodiments of the present invention, the structural formula of the metal complex formed by the dicarboxylic acid and its derivatives and metal ions is as shown in formula III below:

[0030]

[0031] In formula III, R1 and R2 are the same or different, and each of R1 and R2 independently selected from a hydrogen atom, a linear or branched alkyl group having 1 to 10 carbon atoms, and M is a metal ion; preferably, R1 and R2 are the same or different, and each of R1 and R2 independently selected from a hydrogen atom, a linear or branched alkyl group having 1 to 5 carbon atoms, and M is a metal ion.

[0032] In the above method for removing metal from a polymer, preferably, the solid content in the polymer solution to be treated is 5% - 50% (mass percentage), more preferably 10% - 40% (mass percentage).

[0033] In the above method for removing metal from a polymer, preferably, the polymer in the polymer solution to be treated may include a cycloolefin copolymer (COC), a cycloolefin polymer (COP), polyethylene, polypropylene, a polyolefin plastomer (POP), and a polyolefin elastomer (POE), etc., or a combination of one or more thereof.

[0034] In the above method for removing metal from a polymer, preferably, the solvent in the polymer solution to be treated includes toluene, cyclohexane, methylcyclohexane, etc., or a combination of one or more thereof.

[0035] In some specific embodiments of the present invention, the polymer solution to be treated may come from a polymerization reaction unit in a polymer production process, specifically, it may come from a polymerization reaction kettle in a solution polymerization process.

[0036] In the above method for polymer demetallization, preferably, the metals in the polymer solution to be treated include one or a combination of several of vanadium, titanium, zirconium, etc., and aluminum, etc. More preferably, the metals in the polymer solution to be treated include zirconium and aluminum, etc.

[0037] In the above method for polymer demetallization, preferably, the mixing ratio of the polymer solution to be treated and the complexing agent is 1 g of polymer: 10 -5 -10 -3 mol of complexing agent (i.e., one or a combination of several of dicarboxylic acids and their derivatives).

[0038] In the above method for polymer demetallization, preferably, the complexing agent is added to the polymer solution to be treated in the form of a solution, and the concentration of one or a combination of several of dicarboxylic acids and their derivatives in the complexing agent solution is 0.1 - 10 mol / L, more preferably 0.1 - 5 mol / L.

[0039] In some specific embodiments of the present invention, the solvent in the complexing agent solution includes one or a combination of several of water, alcohols, ketones, and hydrocarbons, preferably including one or a combination of several of water, ethanol, and acetone, etc.

[0040] In the above method for polymer demetallization, preferably, the mixing ratio of the polymer solution to be treated and the hydrazine hydrate is 1 g of polymer: 10 -5 -10 -3 mol of hydrazine hydrate.

[0041] In the above method for polymer demetallization, preferably, the hydrazine hydrate is added to the polymer solution to be treated in the form of a solution, and the mass fraction of hydrazine hydrate in the hydrazine hydrate solution is 20% - 80%, more preferably 40% - 80%.

[0042] In some specific embodiments of the present invention, the solvent in the hydrazine hydrate solution includes water and / or alcohols, etc.

[0043] In the above method for polymer demetallization, preferably, in step (1), the process of mixing and reacting the polymer solution to be treated with the complexing agent and hydrazine hydrate is carried out under stirring conditions, and the rotation speed of the stirring can be adjusted by those skilled in the art according to the production scale, and preferably vigorous stirring is adopted.

[0044] In the above method for polymer demetallization, preferably, in step (1), the temperature of mixing and reacting the polymer solution to be treated with the complexing agent and hydrazine hydrate is 60 - 150 °C, more preferably 80 - 130 °C.

[0045] In the above method for polymer demetallization, preferably, in step (1), the reaction time of the polymer solution to be treated with the complexing agent and hydrazine hydrate is 2 - 100 minutes, more preferably 5 - 60 minutes.

[0046] In the above method for polymer demetallization, preferably, the adsorbent includes an oxide adsorbent; more preferably, the adsorbent includes one or a combination of several of aluminum oxide, zinc oxide, silica, etc.

[0047] In the above method for polymer demetallization, preferably, the shape of the adsorbent includes one or a combination of several of powder, sphere, strip, etc. Among them, the strip can include shapes such as clover, four - leaf clover, cylinder, etc. The size of the adsorbent can be conventionally adjusted by those skilled in the art, and the present invention does not specifically limit it.

[0048] In the above method for polymer demetallization, preferably, the bulk density of the adsorbent is 0.35 - 0.8 g / mL, more preferably 0.4 - 0.6 g / mL.

[0049] In the above method for polymer demetallization, preferably, the specific surface area of the adsorbent is 200 - 350 m 2 / g, and the pore volume is 0.4 - 0.8 mL / g.

[0050] In the above method for polymer demetallization, preferably, in step (2), the separation temperature is 30 - 120 °C, more preferably 50 - 100 °C.

[0051] In the above method for polymer demetallization, preferably, in step (2), the separation pressure is 0.1 - 5.0 Mpa, more preferably 0.2 - 3.0 Mpa.

[0052] In the above method for polymer demetallization, preferably, in step (2), the volume space velocity of the mixed liquid for the separation is 0.1 - 10 h -1 and more preferably 0.5 - 8 h -1 .

[0053] According to the specific embodiments of the present invention, preferably, the above method for polymer demetallization further includes step (3): mixing the demetallized polymer solution with an alcohol to precipitate the demetallized polymer in the form of a precipitate, thereby obtaining the demetallized polymer. More preferably, the alcohol used includes one or a combination of several of methanol, ethanol, propanol, isopropanol, etc.; further preferably, the alcohol used is ethanol, etc. More preferably, the mixing volume ratio of the demetallized polymer solution to the alcohol is 1:(1 - 20).

[0054] In some specific embodiments of the present invention, the alcohol used can be an alcohol solution, and its mass fraction or volume fraction can be adjusted conventionally by those skilled in the art.

[0055] In some specific embodiments of the present invention, step (3) may further include: after subjecting the de-metallized polymer precipitated in the form of a precipitate to conventional operations such as solid-liquid separation (such as filtration) and drying, the de-metallized polymer is obtained.

[0056] The present invention provides a method for de-metallizing a polymer, especially a method for removing residual metals of a main catalyst and a co-catalyst in a polymer (mainly polyolefin). The method of the present invention uses a dicarboxylic acid and its derivatives having a cis structure in the spatial configuration as a metal complexing reagent, which reacts with metal ions in the polymer solution to form metal complexes, especially undergoes a complexation reaction with aluminum ions in the polymer solution to generate a water-soluble aluminum ion complex. Then, hydrazine hydrate is used as a strong reducing reagent to reduce residual metal ions such as zirconium and aluminum in the polymer solution to metal atoms, forming a precipitate. Then, the precipitate is filtered and separated through an adsorption column filled with an oxide adsorbent, thereby completing the removal of metal atoms, and the obtained filtrate is a de-metallized polymer solution.

[0057] The method for de-metallizing a polymer of the present invention has at least the following beneficial technical effects:

[0058] 1. In the absence of a complexing agent, aluminum ions will form a flocculent aluminum hydroxide precipitate under the alkaline conditions during the reduction by hydrazine hydrate. This precipitate will be further coated by the polymer and exist as oil-soluble microparticles in the polymer solution, preventing the aluminum ions from reacting with hydrazine hydrate in the reduction reaction, resulting in a low removal rate of aluminum ions and unable to achieve deep removal of metal ions. The present invention uses a dicarboxylic acid and its derivatives having a cis structure in the spatial configuration as a complexing reagent. Compared with traditional complexing reagents, the dicarboxylic acid and its derivatives having a cis structure in the space can quickly form stable metal ion complexes with aluminum ions, avoiding the formation of a gel-like white precipitate of aluminum hydroxide of metal aluminum ions under alkaline conditions, and significantly improving the removal efficiency of metal ions.

[0059] 2. The present invention uses hydrazine hydrate as a reducing de-metallizing reagent. Hydrazine hydrate has strong reducibility and can quickly and efficiently react with metal ions in the polymer to generate metal atoms, forming a precipitate. The by-products are discharged from the system in the form of amines and nitrogen. The by-products are easily separated, have no influence on the performance of the polymer, and the operation is simple and feasible.

[0060] 3. Since hydrazine hydrate is used as the reducing demetallization reagent in the present invention, the main function of the adsorbent is to filter metal atoms, and there is basically no need to adsorb metal ions, thus avoiding the problem that the service life of the adsorbent is affected due to adsorption saturation. The service life of the adsorbent can be greatly extended, and it can operate stably for a long period without replacing the adsorbent.

[0061] 4. In the present invention, oxides are used as the adsorbent to complete the removal of metal atoms. The preparation process of the adsorbent is simple, with high adsorption capacity, not easy to swell, small pressure drop in the adsorbent bed, good long-term operation stability, and low operating cost.

[0062] Therefore, the polymer demetallization method of the present invention can efficiently remove residual metal ions in the polymer solution, and significantly reduce the metal residue in polymer products, especially polyolefin products. Compared with the traditional polymer demetallization technology, the technical solution of the present invention has the advantages of high demetallization efficiency, fast speed, simple process, low cost, and no need for water washing. It can be widely applied to the field of polymer metal removal, with universality and high efficiency, and broad industrialization prospects. Specific Embodiments

[0063] For a clearer understanding of the technical features, objectives, and beneficial effects of the present invention, the technical solution of the present invention will be described in detail below, but it should not be construed as a limitation on the implementable scope of the present invention.

[0064] According to the specific embodiments of the present invention, preferably, the polymer demetallization method provided by the present invention includes the following steps:

[0065] (1) Under the conditions of 60 - 150 °C (preferably 80 - 130 °C) and vigorous stirring, a complexing agent solution and a hydrazine hydrate solution are respectively added to the polymer solution to be treated, and the reaction is carried out for 2 - 100 minutes (preferably 5 - 60 minutes) under vigorous stirring. After the complexing agent reacts with the metal ions in the polymer solution to be treated, metal complexes are formed, especially the complexing reaction with aluminum ions to generate water-soluble aluminum ion complexes, avoiding the formation of aluminum hydroxide precipitation when hydrazine hydrate is added under alkaline conditions. Hydrazine hydrate undergoes a reduction reaction with metal ions such as zirconium and aluminum in the polymer solution to be treated to form metal atoms, obtaining a mixed solution;

[0066] Among them, the solid content in the polymer solution to be treated is 5%-50% (mass percentage), preferably 10%-40% (mass percentage); the polymer in the polymer solution to be treated may include one or a combination of several of cycloolefin copolymer, cycloolefin polymer, polyethylene, polypropylene, polyolefin plastomer, polyolefin elastomer, etc.; the solvent in the polymer solution to be treated includes one or a combination of several of toluene, cyclohexane, methylcyclohexane, etc.; the polymer solution to be treated may come from the polymerization reaction unit in the polymer production process, specifically, it may come from the polymerization reactor in the solution polymerization process.

[0067] The mixing ratio of the polymer solution to be treated and the complexing agent is 1 g polymer: 10 -5 -10 -3 mol of complexing agent; the mixing ratio of the polymer solution to be treated and the hydrazine hydrate is 1 g polymer: 10 -5 -10 -3 mol of hydrazine hydrate.

[0068] The complexing agent solution and the hydrazine hydrate solution are obtained by premixing the complexing agent, hydrazine hydrate and solvent respectively; the concentration of one or a combination of several of the dicarboxylic acid and its derivatives in the complexing agent solution is 0.1-10 mol / L, more preferably 0.1-5 mol / L; the solvent in the complexing agent solution may include one or a combination of several of water, alcohols, ketones and hydrocarbons, preferably including one or a combination of several of water, ethanol and acetone, etc.; the mass fraction of hydrazine hydrate in the hydrazine hydrate solution is 20%-80%, preferably 40%-80%; the solvent in the hydrazine hydrate solution may include water and / or alcohol, etc., preferably water and / or ethanol, etc.

[0069] (2) Under the temperature and pressure conditions of 30-120 °C (preferably 50-100 °C) and 0.1-5.0 Mpa (preferably 0.2-3.0 Mpa), the mixed liquid passes through an adsorption column filled with an adsorbent at a volumetric space velocity of 0.1-10 h -1 (preferably 0.5-8 h -1 ) for separation, and the filtrate obtained is the polymer solution after demetallization.

[0070] Among them, the adsorbent includes an oxide adsorbent; preferably, the adsorbent includes one or a combination of several of aluminum oxide, zinc oxide, silicon dioxide, etc.; the shape of the adsorbent includes one or a combination of several of powder, sphere, strip, etc., among which the strip may include shapes such as clover, four-leaf clover, cylinder, etc.; the bulk density of the adsorbent is 0.35-0.8 g / mL, preferably 0.4-0.6 g / mL; the specific surface area of the adsorbent is 200-350 m2 / g, with a pore volume of 0.4 - 0.8 mL / g;

[0071] (3) Add the metal - removed polymer solution to an alcohol, so that the metal - removed polymer precipitates out, and obtain the metal - removed polymer;

[0072] Among them, the alcohol used includes one or a combination of several of methanol, ethanol, propanol, isopropanol, etc.; preferably, the alcohol used is ethanol, etc.; the mixing volume ratio of the metal - removed polymer solution to the alcohol is 1:(1 - 20); the alcohol used can be an alcohol solution, and its mass fraction or volume fraction can be routinely adjusted by those skilled in the art.

[0073] Example 1

[0074] This example provides a method for polymer demetallization, which includes the following steps:

[0075] (1) Heat 500 mL of a COC toluene solution with a solid content of 10% (mass percentage) to 80 °C, add 5 mL of a 0.1 mol / L maleic acid aqueous solution and 0.063 mL of a 40% hydrazine hydrate aqueous solution under vigorous stirring conditions, and continue to react for 5 minutes under vigorous stirring conditions to obtain a mixed solution;

[0076] (2) Let the mixed solution pass through an adsorption column filled with aluminum oxide powder at a temperature and pressure of 50 °C and 0.2 Mpa with a volume space velocity of 0.5 h -1 to be separated, and the obtained filtrate is the metal - removed polymer solution, which is denoted as S1; among them, the bulk density of the aluminum oxide powder is 0.4 g / mL, the specific surface area is 220 m 2 / g, and the pore volume is 0.4 mL / g;

[0077] (3) Take 500 mL of the filtrate S1 and add it to 2000 mL of an ethanol solution with a volume fraction of 95%, so that the metal - removed polymer precipitates out in the form of a white precipitate. After filtering and drying the white precipitate, obtain the metal - removed polymer product, denoted as P1.

[0078] Use the method of this example to perform long - cycle demetallization on the COC toluene solution. The long - cycle operation time is 2000 hours, and the adsorbent is not replaced during the operation.

[0079] The non - demetallized polymer obtained from the COC toluene solution through step (3) of this example is measured for its metal content by the ignition method, as shown in Table 1.

[0080] The Zr content in the polymer product P1 measured by the ignition method is 0.02 ppm, and the Al content is 0.15 ppm.

[0081] The specific steps for determining the metal content in the polymer by the ignition method are conventional technical means in the art. In the examples and comparative examples of the present invention, the ignition method specifically includes: taking 100 g of the polymer without metal removal or the polymer product after metal removal and placing it in a muffle furnace. Using a programmed temperature rise, the temperature is raised to 650 °C in 1 hour, and then held at a constant temperature for 2 hours to ensure complete combustion of the polymer. After that, it is cooled to room temperature. The ash residue after ignition is added to 5 mL of hydrochloric acid solution (the mass fraction of this hydrochloric acid solution is 19%), and after the ash is completely digested, the metal content in the solution is analyzed by ICP-MS.

[0082] Example 2

[0083] This example provides a method for removing metal from a polymer, which includes the following steps:

[0084] (1) Heat 500 mL of a COC cyclohexane solution with a solid content of 15% (mass percentage) to 90 °C, add 15 mL of a maleic anhydride ethanol solution with a concentration of 0.5 mol / L and 9.38 mL of a hydrazine hydrate ethanol solution with a mass fraction of 40% under vigorous stirring conditions, and continue to react for 10 minutes under vigorous stirring conditions to obtain a mixed solution;

[0085] (2) Under the temperature and pressure conditions of 60 °C and 0.5 Mpa, pass the mixed solution through an adsorption column filled with zinc oxide powder at a volume space velocity of 2.0 h -1 for separation. The obtained filtrate is the polymer solution after metal removal, and this filtrate is denoted as S2; wherein, the bulk density of the zinc oxide powder is 0.45 g / mL, the specific surface area is 280 m 2 / g, and the pore volume is 0.5 mL / g;

[0086] (3) Take 500 mL of filtrate S2 and add it to 2000 mL of an ethanol solution with a volume fraction of 95%, so that the polymer after metal removal precipitates in the form of a white precipitate. After filtering and drying the white precipitate, a polymer product after metal removal is obtained, denoted as P2.

[0087] Using the method of this example for long-term metal removal of the COC cyclohexane solution, the long-term operation time is 2200 hours, and the adsorbent is not replaced during the operation.

[0088] The polymer without metal removal is obtained from the COC cyclohexane solution through step (3) of this example, and its metal content is measured by the ignition method, as shown in Table 1.

[0089] The Zr content in the polymer product P2 measured by the ignition method is 0.03 ppm, and the Al content is 0.19 ppm.

[0090] Example 3

[0091] This example provides a method for polymer demetallization, which includes the following steps:

[0092] (1) Heat 500 mL of a COC methylcyclohexane solution with a solid content of 20% (mass percentage) to 100 °C, and add 100 mL of a 1 mol / L cis-methylmaleic acid acetone solution and 8.3 mL of a 60% hydrazine hydrate aqueous solution under vigorous stirring. Continue to react for 20 minutes under vigorous stirring to obtain a mixed solution;

[0093] (2) Under the temperature and pressure conditions of 70 °C and 1.0 Mpa, pass the mixed solution through an adsorption column filled with silica powder at a volume space velocity of 4.0 h -1 to separate, and the obtained filtrate is the demetallized polymer solution, which is denoted as S3; wherein, the bulk density of the silica powder is 0.5 g / mL, the specific surface area is 300 m 2 / g, and the pore volume is 0.6 mL / g;

[0094] (3) Take 500 mL of the filtrate S3 and add it to 2000 mL of an ethanol solution with a volume fraction of 95% to precipitate the demetallized polymer in the form of a white precipitate. After filtering and drying the white precipitate, the demetallized polymer product is obtained, denoted as P3.

[0095] The method of this example is used for long-term demetallization of the COC methylcyclohexane solution. The long-term operation time is 2300 hours, and the adsorbent is not replaced during the operation.

[0096] The undemetallized polymer is obtained by subjecting the COC methylcyclohexane solution to step (3) of this example, and its metal content is measured by the ignition method, as shown in Table 1.

[0097] The Zr content in the polymer product P3 measured by the ignition method is 0.04 ppm, and the Al content is 0.22 ppm.

[0098] Example 4

[0099] This example provides a method for polymer demetallization, which includes the following steps:

[0100] (1) Heat a 500 mL toluene solution of COC with a solid content of 25% (mass percentage) to 110 °C. Under vigorous stirring, add 0.7 mL of an aqueous solution of 2-methylmaleic anhydride with a concentration of 2 mol / L and 5 mL of a hydrazine hydrate ethanol solution with a mass fraction of 70%. Continue to react for 30 minutes under vigorous stirring to obtain a mixed solution.

[0101] (2) Under the temperature and pressure conditions of 80 °C and 1.5 Mpa, let the mixed solution pass through an adsorption column filled with aluminum oxide powder at a volume space velocity of 6.0 h -1 for separation. The obtained filtrate is the polymer solution after demetallization, and this filtrate is denoted as S4. Among them, the bulk density of the aluminum oxide powder is 0.55 g / mL, the specific surface area is 320 m 2 / g, and the pore volume is 0.7 mL / g.

[0102] (3) Take 500 mL of the filtrate S4 and add it to 2000 mL of an ethanol solution with a volume fraction of 95%. The polymer after demetallization precipitates in the form of a white precipitate. After filtering and drying the white precipitate, a polymer product after demetallization is obtained, denoted as P4.

[0103] Using the method of this example for long-term demetallization of the COC toluene solution, the long-term operation time is 2400 hours, and the adsorbent is not replaced during the operation.

[0104] The polymer without demetallization is obtained from the COC toluene solution through step (3) of this example, and its metal content is measured by the ignition method, as shown in Table 1.

[0105] The Zr content in the polymer product P4 measured by the ignition method is 0.04 ppm, and the Al content is 0.36 ppm.

[0106] Example 5

[0107] This example provides a method for polymer demetallization, which includes the following steps:

[0108] (1) Heat a 500 mL cyclohexane solution of COC with a solid content of 30% (mass percentage) to 120 °C. Under vigorous stirring, add 5 mL of a 2,3-dimethylmaleic anhydride ethanol solution with a concentration of 3 mol / L and 2 mL of a hydrazine hydrate aqueous solution with a mass fraction of 80%. Continue to react for 40 minutes under vigorous stirring to obtain a mixed solution.

[0109] (2) Under the temperature and pressure conditions of 90 °C and 2.0 Mpa, let the mixed solution pass through at a volume space velocity of 7.0 h -1The volumetric space velocity is separated through an adsorption column filled with zinc oxide powder, and the obtained filtrate is the polymer solution after demetallization, which is denoted as S5; wherein, the bulk density of the zinc oxide powder is 0.6 g / mL, the specific surface area is 350 m 2 / g, and the pore volume is 0.8 mL / g;

[0110] (3) Take 500 mL of the filtrate S5 and add it to 2000 mL of an ethanol solution with a volume fraction of 95%, so that the polymer after demetallization precipitates in the form of a white precipitate. After filtering and drying the white precipitate, a polymer product after demetallization is obtained, which is denoted as P5.

[0111] Using the method of this example for long-term demetallization of the COC cyclohexane solution, the long-term operation time is 2600 hours, and the adsorbent is not replaced during the operation.

[0112] The COC cyclohexane solution is processed through step (3) of this example to obtain the polymer without demetallization, and its metal content is measured by the ignition method, as shown in Table 1.

[0113] The Zr content in the polymer product P5 measured by the ignition method is 0.05 ppm, and the Al content is 0.24 ppm.

[0114] Example 6

[0115] This example provides a method for demetallizing a polymer, which includes the following steps:

[0116] (1) Heat 500 mL of a COC methylcyclohexane solution with a solid content of 40% (mass percentage) to 130 °C, and add 40 mL of a 2,3-dimethylmaleic anhydride acetone solution with a concentration of 5 mol / L and 2 mL of a hydrazine hydrate ethanol solution with a mass fraction of 80% under vigorous stirring conditions. Continue to react for 60 minutes under vigorous stirring conditions to obtain a mixed solution;

[0117] (2) Under the temperature and pressure conditions of 100 °C and 3.0 Mpa, make the mixed solution pass through an adsorption column filled with silica powder at a volumetric space velocity of 8.0 h -1 for separation, and the obtained filtrate is the polymer solution after demetallization, which is denoted as S6; wherein, the bulk density of the silica powder is 0.45 g / mL, the specific surface area is 280 m 2 / g, and the pore volume is 0.45 mL / g;

[0118] (3) Take 500 mL of the filtrate S6 and add it to 2000 mL of an ethanol solution with a volume fraction of 95%, so that the polymer after demetallization precipitates in the form of a white precipitate. After filtering and drying the white precipitate, a polymer product after demetallization is obtained, which is denoted as P6.

[0119] Using the method of this embodiment to perform long - term demetallization on the COC methylcyclohexane solution, the long - term operation time is 2900 hours, and the adsorbent is not replaced during the operation.

[0120] The COC methylcyclohexane solution is subjected to the step (3) of this embodiment to obtain a polymer without demetallization, and its metal content is measured by the ignition method, as shown in Table 1.

[0121] The Zr content in the polymer product P6 measured by the ignition method is 0.04 ppm, and the Al content is 0.31 ppm.

[0122] Comparative Example 1

[0123] This comparative example provides a method for polymer demetallization, which includes the following steps:

[0124] (1) Heat 500 mL of a COC toluene solution with a solid content of 10% (mass percentage), which is the same as that in Example 1, to 80 °C. Under vigorous stirring conditions, add 5 mL of an aqueous adipic acid solution with a concentration of 0.1 mol / L, and continue to react for 5 minutes under vigorous stirring conditions to obtain a mixed solution;

[0125] (2) Under the temperature and pressure conditions of 50 °C and 0.2 Mpa, allow the mixed solution to pass through an adsorption column filled with aluminum oxide powder at a volumetric space velocity of 0.5 h -1 for adsorption separation. The filtrate obtained is a polymer solution after demetallization, and this filtrate is denoted as S7; among them, the bulk density of the aluminum oxide powder is 0.4 g / mL, the specific surface area is 220 m 2 / g, and the pore volume is 0.4 mL / g;

[0126] (3) Take 500 mL of the filtrate S7 and add it to 2000 mL of an ethanol solution with a volume fraction of 95%, so that the polymer after demetallization precipitates in the form of a white precipitate. After filtering and drying the white precipitate, a polymer product after demetallization is obtained, denoted as P7.

[0127] Using the method of this comparative example to perform long - term demetallization on the COC toluene solution, the long - term operation time is 400 hours, and the adsorbent is not replaced during the operation.

[0128] The Zr content in the polymer product P7 measured by the ignition method is 1.8 ppm, and the Al content is 12 ppm.

[0129] Comparative Example 2

[0130] This comparative example provides a method for polymer demetallization, which includes the following steps:

[0131] (1) Heat 500 mL of the COC toluene solution with a solid content of 10% (mass percentage), which is the same as that in Example 1, to 80 °C. Add 5 mL of a citric acid aqueous solution with a concentration of 0.1 mol / L under vigorous stirring conditions. After continuing to react for 5 minutes under vigorous stirring conditions, a mixed solution is obtained;

[0132] (2) Under the temperature and pressure conditions of 50 °C and 0.2 Mpa, let the mixed solution pass through an adsorption column filled with aluminum oxide powder at a volume space velocity of 0.5 h -1 for adsorption separation. The obtained filtrate is the polymer solution after demetallization, and this filtrate is denoted as S8; wherein, the bulk density of the aluminum oxide powder is 0.4 g / mL, the specific surface area is 220 m 2 / g, and the pore volume is 0.4 mL / g;

[0133] (3) Take 500 mL of the filtrate S8 and add it to 2000 mL of an ethanol solution with a volume fraction of 95%. Let the polymer after demetallization precipitate in the form of a white precipitate. After filtering and drying the white precipitate, a polymer product after demetallization is obtained, denoted as P8.

[0134] Using the method of this comparative example to carry out long - cycle demetallization of the COC toluene solution, the long - cycle operation time is 400 hours, and the adsorbent is not replaced during the operation.

[0135] The Zr content in the polymer product P8 measured by the ignition method is 2.1 ppm, and the Al content is 14 ppm.

[0136] Comparative Example 3

[0137] This comparative example provides a method for polymer demetallization, which includes the following steps:

[0138] (1) Take 250 mL of the aluminum oxide powder used in step (2) of Example 1. After heating to 100 °C, add 100 mL of a maleic acid aqueous solution with a concentration of 0.005 mol / L. Continue to stir for 2 hours, then filter. Take the filter residue and dry it at 120 °C for 8 hours to obtain maleic acid - pretreated aluminum oxide powder; the bulk density of this maleic acid - pretreated aluminum oxide powder is 0.41 g / mL, the specific surface area is 212 m 2 / g, and the pore volume is 0.42 mL / g;

[0139] (2) Heat 500 mL of the COC toluene solution with a solid content of 10% (mass percentage), which is the same as that in Example 1, to 50 °C. Under the temperature and pressure conditions of 50 °C and 0.2 Mpa, at a volume space velocity of 0.5 h -1The volumetric space velocity is passed through an adsorption column filled with the alumina powder pretreated with maleic acid for adsorption separation, and the obtained filtrate is the polymer solution after demetallization, and this filtrate is denoted as S9;

[0140] (3) Take 500 mL of the filtrate S9 and add it to 2000 mL of an ethanol solution with a volume fraction of 95%, so that the polymer after demetallization precipitates in the form of a white precipitate. After filtering and drying the white precipitate, a polymer product after demetallization is obtained, denoted as P9.

[0141] The method of this comparative example is used for long-term demetallization of the COC toluene solution. The long-term operation time is 400 hours, and the adsorbent is not replaced during the operation.

[0142] The Zr content in the polymer product P9 measured by the ignition method is 4.5 ppm, and the Al content is 32 ppm.

[0143] Comparative Example 4

[0144] This comparative example provides a method for polymer demetallization, which includes the following steps:

[0145] (1) Heat 500 mL of a COC toluene solution with a solid content of 10% (mass percentage, the same as in Example 1) to 80 °C, and add 66 mL of an EDTA aqueous solution with a mass fraction of 11% (7.3 g of EDTA) and 5 mL of an ethylenediamine aqueous solution with a concentration of 0.1 mol / L under vigorous stirring conditions. Continue to react for 5 minutes under vigorous stirring conditions to obtain a mixed solution;

[0146] (2) Under the temperature and pressure conditions of 50 °C and 0.2 Mpa, let the mixed solution pass through an adsorption column filled with alumina powder at a volumetric space velocity of 0.5 h -1 for separation. The obtained filtrate is the polymer solution after demetallization, and this filtrate is denoted as S10; wherein, the bulk density of the alumina powder is 0.4 g / mL, the specific surface area is 220 m 2 / g, and the pore volume is 0.4 mL / g;

[0147] (3) Take 500 mL of the filtrate S10 and add it to 2000 mL of an ethanol solution with a volume fraction of 95%, so that the polymer after demetallization precipitates in the form of a white precipitate. After filtering and drying the white precipitate, a polymer product after demetallization is obtained, denoted as P10.

[0148] The method of this comparative example is used for long-term demetallization of the COC toluene solution. The long-term operation time is 400 hours, and the adsorbent is not replaced during the operation.

[0149] The Zr content in the polymer product P10 measured by the ignition method was 5.1 ppm, and the Al content was 34 ppm.

[0150] Comparative Example 5

[0151] This comparative example provides a method for polymer demetallization, which includes the following steps:

[0152] (1) Heat 500 mL of a COC toluene solution with a solid content of 10% (mass percentage) to 80 °C, and add 66 mL of an EDTA aqueous solution with a mass fraction of 11% (7.3 g of EDTA) and 0.063 mL of a hydrazine hydrate aqueous solution with a mass fraction of 40% under vigorous stirring conditions. Continue to react for 5 minutes under vigorous stirring conditions to obtain a mixed solution;

[0153] (2) Under the temperature and pressure conditions of 50 °C and 0.2 Mpa, pass the mixed solution through an adsorption column filled with aluminum oxide powder at a volume space velocity of 0.5 h -1 for separation. The obtained filtrate is the polymer solution after demetallization, and this filtrate is denoted as S11; among them, the bulk density of the aluminum oxide powder is 0.4 g / mL, the specific surface area is 220 m 2 / g, and the pore volume is 0.4 mL / g;

[0154] (3) Take 500 mL of the filtrate S11 and add it to 2000 mL of an ethanol solution with a volume fraction of 95% to precipitate the demetallized polymer in the form of a white precipitate. After filtering and drying the white precipitate, the demetallized polymer product is obtained, denoted as P11.

[0155] Using the method of this comparative example for long-term demetallization of the COC toluene solution, the long-term operation time is 400 hours, and the adsorbent is not replaced during the operation.

[0156] The Zr content in the polymer product P11 measured by the ignition method was 0.03 ppm, and the Al content was 11 ppm.

[0157] The results of the polymer demetallization methods provided in the above Examples 1-6 and Comparative Examples 1-5 are shown in Table 1.

[0158] Table 1 Polymer Demetallization Experiment Results

[0159]

[0160] As can be seen from the experimental results in Table 1, the method for polymer demetallization in Examples 1-6 of the present invention has a significant effect on the removal of metals in the polymer, and the removal efficiency is significantly superior to that of Comparative Examples 1-5. Moreover, the operation time of the adsorbent is longer than that of Comparative Examples 1-5. At the same time, the method for polymer demetallization of the present invention is simple to operate, low in cost, and has broad industrialization prospects.

Claims

1. A method for polymer demetallization, which comprises the following steps: (1) After mixing and reacting a polymer solution to be treated with a complexing agent and hydrazine hydrate, a mixed solution is obtained; (2) The mixed solution is separated by passing through an adsorption column filled with an adsorbent, and the filtrate obtained is the polymer solution after demetallization; Wherein, the complexing agent includes one or a combination of several of dicarboxylic acids and their derivatives; the dicarboxylic acid contains a carbon-carbon double bond and two carboxyl groups are arranged on the same side of the carbon-carbon double bond, and has a cis structure in terms of spatial configuration. The dicarboxylic acid has the structure shown in Formula I below: Formula I In Formula I, R1 and R2 are the same or different, and R1 and R2 are each independently selected from an H atom, a straight-chain or branched-chain alkyl group having 1 to 5 carbon atoms; the derivatives of the dicarboxylic acid include one or a combination of several of acid anhydrides, acyl halides, amides, esters, and nitriles formed by the dicarboxylic acid; The polymer in the polymer solution to be treated is a polyolefin.

2. The method for polymer demetallization according to claim 1, wherein The derivative of the dicarboxylic acid includes the acid anhydride of the dicarboxylic acid.

3. The method for polymer demetallization according to claim 1, wherein The dicarboxylic acid and its derivatives include one or a combination of several of maleic acid, maleic anhydride, cis-methylmaleic acid, cis-methylmaleic anhydride, 2,3-dimethylmaleic acid, and 2,3-dimethylmaleic anhydride.

4. The method for polymer demetallization according to claim 1, wherein The solid content in the polymer solution to be treated is 5% - 50%.

5. The method for polymer demetallization according to claim 4, wherein, The solid content in the polymer solution to be treated is 10% - 40%.

6. The method for polymer demetallization according to claim 1, wherein, The polymer in the polymer solution to be treated includes one or a combination of several of cycloolefin copolymer (COC), cycloolefin polymer (COP), polyethylene, polypropylene, polyolefin plastomer, and polyolefin elastomer.

7. The method for demetallizing a polymer according to claim 1, wherein, The metals in the polymer solution to be treated include one or a combination of several of vanadium, titanium, and zirconium, and aluminum.

8. The method for polymer demetallization according to claim 1, wherein, The mixing ratio of the polymer solution to be processed and the complexing agent is 1 g of polymer: 10 -5 - 10 -3 mol of complexing agent.

9. The method for polymer demetallization according to claim 8, wherein, The complexing agent is added to the polymer solution to be treated in the form of a solution, and the concentration of one or a combination of several of the dicarboxylic acid and its derivatives in the complexing agent solution is 0.1 - 10 mol / L.

10. The method for demetallizing a polymer according to claim 9, wherein, The concentration of one or a combination of several of the dicarboxylic acid and its derivatives in the complexing agent solution is 0.1 - 5 mol / L.

11. The method for polymer demetallization according to claim 9, wherein, The solvent in the complexing agent solution includes one or a combination of several of water, alcohols, ketones, and hydrocarbons.

12. The method for polymer demetallization according to claim 1, wherein, The mixing ratio of the polymer solution to be treated and the hydrazine hydrate is 1 g of polymer: 10 -5 - 10 -3 mol of hydrazine hydrate.

13. The method for polymer demetallization according to claim 12, wherein, The hydrazine hydrate is added to the polymer solution to be treated in the form of a solution, and the mass fraction of hydrazine hydrate in the hydrazine hydrate solution is 20% - 80%.

14. The method for polymer demetallization according to claim 13, wherein, The mass fraction of hydrazine hydrate in the hydrazine hydrate solution is 40% - 80%.

15. The method for polymer demetallization according to claim 13, wherein, The solvent in the hydrazine hydrate solution includes water and / or alcohol.

16. The method for polymer demetallization according to claim 1, wherein, In step (1), the temperature for mixing and reacting the polymer solution to be treated with the complexing agent and hydrazine hydrate is 60 - 150 °C.

17. The method for polymer demetallization according to claim 16, wherein, In step (1), the temperature for mixing and reacting the polymer solution to be treated with the complexing agent and hydrazine hydrate is 80 - 130 °C.

18. The method for polymer demetallization according to claim 1, wherein, In step (1), the reaction time of the polymer solution to be treated with the complexing agent and hydrazine hydrate is 2 - 100 minutes.

19. The method for demetallizing a polymer according to claim 18, wherein, In step (1), the reaction time of the polymer solution to be treated with the complexing agent and hydrazine hydrate is 5 - 60 minutes.

20. The method for polymer demetallization according to claim 1, wherein, The adsorbent includes an oxide adsorbent.

21. The method for polymer demetallization according to claim 20, wherein, The adsorbent includes one or a combination of several of aluminum oxide, zinc oxide, and silicon dioxide.

22. The method for polymer demetallization according to claim 1 or 20, wherein, The bulk density of the adsorbent is 0.35 - 0.8 g / mL.

23. The method for demetallizing a polymer according to claim 22, wherein, The bulk density of the adsorbent is 0.4 - 0.6 g / mL.

24. The method for demetallizing a polymer according to claim 1 or 20, wherein, The specific surface area of the adsorbent is 200-350 m 2 / g, and the pore volume is 0.4-0.8 mL / g.

25. The method for polymer demetallization according to claim 1, wherein, In step (2), the separation temperature is 30 - 120 °C.

26. The method for demetallizing a polymer according to claim 25, wherein, In step (2), the separation temperature is 50 - 100 °C.

27. The method for polymer demetallization according to claim 1, wherein In step (2), the separation pressure is 0.1 - 5.0 Mpa.

28. The method for demetallizing a polymer according to claim 27, wherein, In step (2), the separation pressure is 0.2 - 3.0 Mpa.

29. The method for polymer demetallization according to claim 1, wherein, In step (2), the volumetric space velocity of the mixed liquid for the separation is 0.1 - 10 h -1 .

30. The method for demetallizing a polymer according to claim 29, wherein, In step (2), the volume space velocity of the mixed liquid for the separation is 0.5 - 8 h -1 .

31. The method for polymer demetallization according to claim 1, wherein, The method for polymer demetallization further includes step (3): mixing the demetallized polymer solution with an alcohol to precipitate the demetallized polymer, thereby obtaining the demetallized polymer.

32. The method for polymer demetallization according to claim 31, wherein, In step (3), the alcohol used includes one or a combination of several of methanol, ethanol, propanol, and isopropanol.

33. The method for polymer demetallization according to claim 31, wherein, In step (3), the mixing volume ratio of the demetallized polymer solution to the alcohol is 1:(1 - 20).

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