A method for treating a polyolefin catalyst waste solution

Abstract

The present application relates to the technical field of organic waste liquid treatment, and discloses a polyolefin catalyst waste liquid treatment method. The polyolefin catalyst waste liquid treatment method comprises the following steps: under an inert atmosphere, carrying out an oxidation-reduction reaction on a titanium-containing organic waste liquid and an organic metal compound-containing waste liquid, and then carrying out solid-liquid separation to obtain a titanium-containing compound and a low-titanium organic waste liquid; the organic metal compound-containing waste liquid comprises at least one of an organic aluminum compound-containing waste liquid or an organic magnesium compound-containing waste liquid; and the low-titanium organic waste liquid is subjected to rectification to obtain an organic solvent and waste. The organic aluminum compound and the organic magnesium compound have high reducibility, and can reduce titanium in the titanium-containing organic waste liquid from tetravalence to trivalence and divalence, and correspondingly, the material state is converted from liquid to solid, thereby improving the recovery rate of titanium in the titanium-containing organic waste liquid; after the low-titanium organic waste liquid is subjected to rectification to recover the organic solvent, the amount of waste is greatly reduced, and the subsequent treatment amount of the three wastes is also greatly reduced.

Description

Technical Field

[0001] This invention relates to the field of organic waste liquid treatment technology, and in particular to a method for treating polyolefin catalyst waste liquid. Background Technology

[0002] Highly active polyolefin catalysts are currently used extensively in the polyolefin industry, with the Ziegler-Natta catalyst being the most commonly used highly active catalyst for polypropylene. The Ziegler-Natta catalyst is prepared by reacting titanium tetrachloride, an organic solvent, a magnesium-containing compound, and an internal electron donor. The resulting solid particles need to be separated from the mother liquor, and the solid particles are washed with a hydrocarbon solvent to remove unreacted titanium compounds and byproducts, ultimately yielding the Ziegler-Natta catalyst. This separation and washing process generates a certain amount of waste liquid. For cost and environmental reasons, the organic solvent and titanium tetrachloride need to be recovered from this waste liquid. Currently, the recovery process involves feeding a mixture containing the organic solvent, titanium tetrachloride, and high-boiling-point substances into a distillation column for separation. The top of the column separates the light organic solvent component, while the bottom contains titanium tetrachloride and high-boiling-point substances. The bottom material is then further separated by distillation to obtain titanium tetrachloride and residual liquid. The residual liquid, after hydrolysis, is acidic and needs to be neutralized with alkali before being discharged as wastewater and waste residue. In this treatment method, the high boiling point content of the material in the bottom of the tower is relatively high, the material viscosity is high, the fluidity is poor, and the long residence time at high temperature can easily lead to coking on the bottom wall, inability to stir, or even shutdown. Therefore, it is difficult to achieve high-efficiency recovery of titanium tetrachloride. Direct hydrolysis and neutralization not only waste raw materials but also increase the amount of waste to be treated.

[0003] The carriers for Ziegler-Natta catalysts include organomagnesia compounds, such as dibutylmagnesium and dioctylmagnesium. The preparation of these organomagnesia compounds generates waste liquid containing organomagnesia compounds. Organomagnesia compounds are highly reactive and hazardous, and improper handling can threaten personal safety. Waste disposal is generally carried out by hydrolysis, which generates a large amount of alkaline wastewater and waste residue.

[0004] Furthermore, to avoid problems such as polymer agglomeration and catalyst breakage leading to high fine powder content in polymer powder during olefin polymerization, a prepolymerization reaction is introduced before olefin polymerization in industrial applications. This results in a more stable release of activity from the Ziegler-Natta catalyst, enabling the production of more high-value-added polyolefin grades. However, the prepolymerization catalyst preparation process involves the addition of excessive organoaluminum compounds and organic solvents, generating wastewater containing high concentrations of organoaluminum compounds. Current treatment methods involve hydrolysis, which produces large amounts of alkaline wastewater and waste residue, placing significant pressure on environmental protection and the economy. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a method for treating polyolefin catalyst waste liquid, which involves subjecting titanium-containing organic waste liquid to an oxidation-reduction reaction with waste liquid containing organometallic compounds. This method can effectively improve the recovery rate of titanium in the titanium-containing organic waste liquid and significantly reduce the quality of the final waste.

[0006] To achieve the above-mentioned objectives, the embodiments of the present invention employ the following technical solutions:

[0007] A method for treating polyolefin catalyst waste liquid includes the following steps:

[0008] S1, under an inert atmosphere, titanium-containing organic waste liquid and waste liquid containing organometallic compounds are subjected to an oxidation-reduction reaction, and solid-liquid separation is performed to obtain titanium-containing compounds and low-titanium organic waste liquid.

[0009] The titanium-containing organic waste liquid is a waste liquid containing tetravalent titanium generated during the preparation of titanium-based polyolefin catalysts;

[0010] The waste liquid containing organometallic compounds includes at least one of waste liquid containing organoaluminum compounds or waste liquid containing organomagnesium compounds; the waste liquid containing organoaluminum compounds includes organic aluminum compounds, and the waste liquid containing organomagnesium compounds includes organic magnesium compounds.

[0011] S2, the low-titanium organic waste liquid is distilled to obtain organic solvent and waste.

[0012] Compared to existing technologies, the polyolefin catalyst waste liquid treatment method provided by this invention involves a redox reaction between titanium-containing organic waste liquid and waste liquid containing organometallic compounds. Aluminum and magnesium in organoaluminum and organomagnesium compounds are reactive metals with high reducing power, capable of reducing titanium in the titanium-containing organic waste liquid from tetravalent to trivalent and divalent, respectively. The corresponding material state changes from liquid to solid, precipitating from the organic waste liquid to obtain low-valent titanium-containing compounds and low-titanium organic waste liquid. The titanium-containing compounds can be recycled, for example, to produce titanium dioxide, thereby improving the titanium recovery rate from the titanium-containing organic waste liquid. The titanium content in the low-titanium organic waste liquid is significantly reduced. After distillation and recovery of the organic solvent, the amount of waste can be significantly reduced, correspondingly reducing the amount of subsequent waste treatment. Furthermore, organoaluminum and organomagnesium compounds are both hazardous wastes. After the redox reaction, chlorine atoms in the titanium-containing organic waste liquid can be removed, ultimately existing as stable aluminum chloride and magnesium chloride, significantly reducing the hazard.

[0013] Preferably, in S1, the titanium-containing organic waste liquid includes titanium tetrachloride, alkoxy titanium chloride, an internal electron donor, magnesium chloride powder, and a first organic solvent.

[0014] Preferably, in S1, the alkoxy titanium chloride includes at least one of methoxy titanium trichloride, ethoxy titanium trichloride, propoxy titanium trichloride, n-butoxy titanium trichloride, dimethoxy titanium dichloride, diethoxy titanium dichloride, dipropoxy titanium dichloride, di-n-butoxy titanium dichloride, trimethoxy titanium chloride, triethoxy titanium chloride, tripropoxy titanium chloride, or tri-n-butoxy titanium chloride.

[0015] Preferably, in S1, the internal electron donor includes at least one of diether compounds, aromatic dicarboxylic acid ester compounds, succinate compounds, aromatic diol ester compounds, aliphatic diol ester compounds, or amine compounds.

[0016] For example, in S1, the internal electron donor includes at least one of di-n-butyl phthalate, 9,9-methoxymethylfluorene, or 2-isopropyl-2-isopentyl-1,3-dimethoxypropane.

[0017] Preferably, in S1, the first organic solvent includes at least one of toluene, benzene, n-hexane, cyclohexane, heptane, dichloromethane, or chloroform.

[0018] More preferably, in S1, the titanium-containing organic waste liquid contains 5wt%~15wt% titanium, 20wt%~35wt% chlorine, 0.1wt%~3wt% internal electron donor, ≤5wt% magnesium chloride powder, and 50wt%~90wt% first organic solvent.

[0019] Preferably, in S1, the waste liquid containing organoaluminum compounds includes an organoaluminum compound, an internal electron donor, and a second organic solvent.

[0020] Preferably, in S1, the aluminum-containing organic compound includes at least one of alkylaluminum, chloroalkylaluminum, or aluminoxane.

[0021] More preferably, in S1, the alkylaluminum includes at least one of triethylaluminum, tributylaluminum, triisobutylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum, or isoprene aluminum.

[0022] More preferably, in S1, the chloroalkyl aluminum includes at least one of diethylaluminum chloride, diethylaluminum chloride, or sesquiethylaluminum chloride.

[0023] More preferably, in S1, the aluminum oxane is at least one of methylaluminoxane, modified methylaluminoxane, ethylaluminoxane, propylaluminoxane, or butylaluminoxane.

[0024] Preferably, in S1, the second organic solvent includes at least one of n-pentane, n-hexane, n-heptane, n-octane, cyclohexane, toluene, ethylbenzene, or xylene.

[0025] More preferably, in S1, the aluminum content in the waste liquid containing organoaluminum compounds is 2wt%~10wt%, the chlorine content is ≤5wt%, the content of internal electron donors is ≤2wt%, and the content of the second organic solvent is 65wt%~95wt%.

[0026] Preferably, in S1, the waste liquid containing organic magnesium compounds includes organic magnesium compounds and a third organic solvent.

[0027] Preferably, in S1, the organomagnesium compound includes at least one of alkyl magnesium or alkyl chloride magnesium.

[0028] More preferably, in S1, the alkyl magnesium includes at least one of dimethyl magnesium, diethyl magnesium, dipropyl magnesium, dibutyl magnesium, dihexyl magnesium, dioctyl magnesium, ethylbutyl magnesium, butylhexyl magnesium, butyloctyl magnesium, methylphenyl magnesium, or ethylphenyl magnesium.

[0029] More preferably, in S1, the alkyl magnesium chloride includes at least one of methyl magnesium chloride, ethyl magnesium chloride, propyl magnesium chloride, butyl magnesium chloride, or phenyl magnesium chloride.

[0030] Preferably, in S1, the third organic solvent includes at least one of n-pentane, n-hexane, n-heptane, n-octane, cyclohexane, toluene, ethylbenzene, or xylene.

[0031] More preferably, in S1, the magnesium content in the waste liquid containing organic magnesium compounds is 5wt%~15wt%, the chlorine content is 5wt%~25wt%, and the content of the third organic solvent is 50wt%~90wt%.

[0032] Preferably, in S1, the titanium-containing organic waste liquid includes at least one of the first catalyst mother liquor, the first washing liquid, or the first distillation residue generated during the preparation of titanium-based polyolefin catalysts.

[0033] More preferably, in S1, the titanium-based polyolefin catalyst includes a Ziegler-Natta catalyst.

[0034] More preferably, in S1, the first distillation residue is the residue after distilling away part of the first solvent from the first catalyst mother liquor and / or the first washing liquid.

[0035] Preferably, in S1, the waste liquid containing organoaluminum compounds includes at least one of the second catalyst mother liquor, the second washing liquid, or the second distillation residue generated during the preparation of the prepolymerization catalyst.

[0036] More preferably, in S1, the second distillation residue is the residue after distilling away part of the second solvent from the second catalyst mother liquor and / or the second washing liquid.

[0037] Preferably, in S1, the waste liquid containing organic magnesium compounds includes waste liquid containing organic magnesium compounds generated during the preparation of polyolefin catalysts.

[0038] For example, in S1, the waste liquid containing organomagnesia compounds can be the residue after distillation to remove some of the organic solvent.

[0039] The method for treating polyolefin catalyst waste liquid provided by this invention can simultaneously treat titanium-containing organic waste liquid and organoaluminum compound waste liquid or organomagnesium compound waste liquid generated during the preparation of polyolefin catalysts. It can not only recover a large amount of titanium from titanium-containing organic waste liquid and reduce the danger of organoaluminum compound waste liquid or organomagnesium compound waste liquid, but also significantly improve the recovery rate of organic solvents in titanium-containing organic waste liquid and organoaluminum compound waste liquid or organomagnesium compound waste liquid. The treatment cost is effectively controlled and it has good market application value.

[0040] It should be noted that the steps for generating titanium-containing organic waste liquid, organoaluminum compound-containing waste liquid, and organomagnesium compound-containing waste liquid can be performed using conventional methods in the field, and the present invention does not impose any special limitations on them.

[0041] Preferably, in S1, the molar ratio of titanium in the titanium-containing organic waste liquid to the metal in the organometallic compound waste liquid is 1:(0.1~30), more preferably 1:(0.1~15), and even more preferably 1:(0.1~5).

[0042] For example, in S1, the inert atmosphere can be a nitrogen atmosphere to isolate oxygen from the air.

[0043] Preferably, in S1, the temperature of the redox reaction is 0℃~100℃, and the reaction time is 1min~150min.

[0044] More preferably, in S1, the temperature of the redox reaction is 10℃~90℃, and the reaction time is 10min~140min.

[0045] Preferably, in S1, the titanium-containing organic compound includes at least three of titanium dichloride, titanium trichloride, low-valent alkoxy titanium chloride, or low-valent alkoxy titanium.

[0046] More preferably, in S1, the low-valent alkoxy titanium chloride includes at least one of methoxy titanium dichloride, ethoxy titanium dichloride, propoxy titanium dichloride, n-butoxy titanium dichloride, dimethoxy titanium monochloride, diethoxy titanium monochloride, dipropoxy titanium monochloride, or di-n-butoxy titanium monochloride.

[0047] More preferably, in S1, the low-valent alkoxy titanium includes at least one of trimethoxy titanium, triethoxy titanium, tripropoxy titanium, or tri-n-butoxy titanium.

[0048] Preferably, in S1, the titanium content in the low-titanium organic waste liquid is ≤3.0wt%, more preferably ≤1.8wt%, and even more preferably ≤0.9wt%.

[0049] During the redox process, titanium tetrachloride and alkoxy titanium chloride in titanium-containing organic waste liquid are reduced to titanium dichloride, titanium trichloride, low-valent alkoxy titanium chloride, or low-valent alkoxy titanium, respectively (the reaction equations can be found in Equations 1 and 2). At the same time, organoaluminum compounds in waste liquid containing organoaluminum compounds and organomagnesium compounds in waste liquid containing organomagnesium compounds can remove chlorine atoms from titanium-containing organic waste liquid to form stable aluminum chloride and magnesium chloride, which greatly reduces the risk and is beneficial for the further treatment of subsequent waste.

[0050] Formula 1

[0051] Formula 2

[0052] In Formula 2, R is the alkyl group corresponding to alkoxytitanium chloride.

[0053] Preferably, in S2, the distillation pressure is -0.02MPa to 0MPa, and the distillation time is 0.5h to 1h.

[0054] It should be noted that the present invention does not impose any special limitation on the distillation temperature in S2; a conventional temperature range in the art can be used depending on the recovered organic solvent.

[0055] For example, in S2, the waste can be incinerated. Detailed Implementation

[0056] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0057] Unless otherwise specified, all materials used in this invention are commercially available products.

[0058] The titanium content was determined by spectrophotometry, the magnesium and aluminum content were determined by EDTA titration, and the internal electron donor content was determined by gas chromatography.

[0059] Example 1

[0060] This embodiment provides a method for treating polyolefin catalyst waste liquid, including the following steps:

[0061] Sa, Preparation of waste liquid containing organic magnesium compounds:

[0062] In a four-necked flask equipped with a stirrer, a reflux condenser was installed and connected to a cumulative gas meter. After the entire reaction apparatus was fully purged with nitrogen, 20 g (0.823 mol) of 250-mesh magnesium powder and 0.3 L of n-heptane purified by molecular sieve were added, followed by 0.5 g of elemental iodine as an initiator. The mixture was stirred and mixed at room temperature for 30 min, and then heated to reflux. Under reflux, 60.9 g (0.658 mol) of 1-chlorobutane was slowly added dropwise. After the addition was complete, the reaction was continued under reflux for 60 min. The mixture was then cooled to room temperature and filtered to obtain a heptane solution of dibutylmagnesium.

[0063] It should be noted that the heptane solution of dibutylmagnesium is one of the raw materials for preparing polyolefin catalysts. The heptane solution of dibutylmagnesium is highly reactive; if flocculent matter or precipitate is found in the heptane solution, it indicates that the dibutylmagnesium has deteriorated or become ineffective, requiring waste liquid treatment (i.e., waste liquid containing organic magnesium compounds). Measurements showed that the waste liquid containing organic magnesium compounds contained 7.0 wt% magnesium, 8.1 wt% chlorine, and 71.6 wt% n-heptane.

[0064] Preparation of Sb-containing organic waste liquid:

[0065] In a stirred five-necked flask fully purged with nitrogen, 10 g of polyolefin catalyst support Mg(OEt)2 and 80 mL of toluene were added to prepare a suspension. Then, 20 mL of titanium tetrachloride was added dropwise at -15 °C. After the addition was complete, the system was slowly heated to 10 °C, and 60 mL of titanium tetrachloride was added dropwise. The temperature was then slowly raised to 80 °C, and 3.5 g of di-n-butyl phthalate was added. The temperature was then raised to 120 °C and held for 2 h. After pressure filtration, the first catalyst mother liquor and the first solid were obtained. The first solid was washed three times with 120 mL of titanium tetrachloride at 125 °C, and then washed twice with 150 mL of n-hexane at 60 °C and twice at room temperature. Solid-liquid separation was performed to obtain the first washing liquid and the second solid. The second solid was dried to obtain the Ziegler-Natta catalyst (analytical titanium content of 2.83 wt% and di-n-butyl phthalate content of 11.24 wt%).

[0066] The mixture of the first catalyst mother liquor and the first washing liquid was subjected to vacuum distillation to recover some of the solvent (a small amount of toluene and all of the n-hexane), yielding the first distillation residue, which is the titanium-containing organic waste liquid. Measurements showed that the titanium-containing organic waste liquid contained 9.6 wt% titanium, 26.3 wt% chlorine, 58.3 wt% toluene, and 1.3 wt% di-n-butyl phthalate.

[0067] In a stirred five-necked flask fully purged with nitrogen, 40.0 g of titanium-containing organic waste liquid (3.84 g titanium, 0.080 mol titanium) was added. Under stirring, 139.2 g of organic magnesium compound waste liquid (9.74 g magnesium, 0.401 mol magnesium) was gradually added. The oxidation-reduction reaction was carried out at 60 °C for 2 h. After cooling to room temperature, the mixture was filtered to obtain 19.3 g of titanium compound solid and low-titanium organic waste liquid.

[0068] Measurements showed that the titanium content in the low-titanium organic waste liquid was 0.09 wt%. It should be noted that during the redox reaction, the butyl group in dibutylmagnesium is converted into butane and butene, which are emitted as gases.

[0069] Sd, low-titanium organic waste liquid was subjected to vacuum distillation to obtain organic solvent (21.3g toluene, 93.4g n-heptane) and 38.8g waste.

[0070] Example 2

[0071] This embodiment provides a method for treating polyolefin catalyst waste liquid, including the following steps:

[0072] Sa, preparation of titanium-containing organic waste liquid: same as Sb in Example 1, and will not be repeated.

[0073] Preparation of waste liquid containing organoaluminum compounds (Sb):

[0074] In a stirred five-necked flask fully purged with nitrogen, 300 mL of n-hexane, 20 mL of 0.5 mol / L triisobutylaluminum hexane solution, and 10 g of the above Ziegler-Natta catalyst were added. After being kept at 5 °C for 5 min, propylene was introduced through a mass flow meter at a rate of 20 g / h. After reacting for 60 min, the propylene flow was stopped, and the mixture was filtered to obtain a second catalyst mother liquor and a third solid. The third solid was washed with n-hexane, and the solid and liquid were separated to obtain a second washing liquid and a fourth solid. The fourth solid was dried under vacuum to obtain 26.4 g of prepolymerized catalyst (analytical titanium content of 1.1 wt%, polymer content of 62.0 wt%, and propylene prepolymerization ratio of 1.6).

[0075] The mixture of the second catalyst mother liquor and the second washing liquid was subjected to vacuum distillation to recover part of the solvent (n-hexane), yielding the second distillation residue, which was the waste liquid containing organoaluminum compounds. Measurements showed that the waste liquid contained 4.1 wt% aluminum, 0.5 wt% chlorine, 0.1 wt% internal electron donor, and 72.3 wt% n-hexane.

[0076] In a stirred five-necked flask fully purged with nitrogen, 40.0 g of titanium-containing organic waste liquid (3.84 g titanium, 0.080 mol titanium) was added. Under stirring, 26.4 g of organic aluminum compound waste liquid (1.08 g aluminum, 0.040 mol aluminum) was gradually added. The reaction was carried out at 40 °C for 2 h. After cooling to room temperature, the mixture was filtered to obtain 13.9 g of titanium compound solid and low-titanium organic waste liquid.

[0077] Measurements showed that the titanium content in the low-titanium organic waste liquid was 1.5 wt%. It should be noted that during the redox reaction, the isobutyl groups in triisobutylaluminum are converted into isobutane and isobutene, which are emitted in gaseous form.

[0078] Sd, low-titanium organic waste liquid was subjected to vacuum distillation to obtain organic solvent (18.7g toluene, 17.2g n-hexane) and 13.7g waste.

[0079] Example 3

[0080] This embodiment provides a method for treating polyolefin catalyst waste liquid, including the following steps:

[0081] Preparation of Sa~Sb waste liquid containing organic magnesium compounds and titanium-containing organic waste liquid: Same as in Example 1, and will not be repeated.

[0082] Preparation of Sc, containing organoaluminum compound waste liquid: same as Sb in Example 2, and will not be repeated.

[0083] In a stirred five-necked flask fully purged with nitrogen, 40.0 g of titanium-containing organic waste liquid (3.84 g titanium, 0.080 mol titanium) was added. Under stirring, 27.8 g of organic magnesium compound waste liquid (1.95 g magnesium, 0.080 mol magnesium) and 26.4 g of organic aluminum compound waste liquid (1.08 g aluminum, 0.040 mol aluminum) were gradually added. The reaction was carried out at 50 °C for 2 h. After cooling to room temperature, the mixture was filtered to obtain 14.2 g of titanium compound solid and low-titanium organic waste liquid.

[0084] Measurements showed that the titanium content in the low-titanium organic waste liquid was 0.48 wt%. It should be noted that during the redox reaction, the butyl group in dibutylmagnesium was converted to butane and butene, and the isobutyl group in triisobutylaluminum was converted to isobutane and isobutene, both emitted as gases.

[0085] Sd, low-titanium organic waste liquid was subjected to vacuum distillation to obtain organic solvents (16.3g toluene, 18.1g n-hexane, 18.9g n-heptane) and 23.6g waste.

[0086] Example 4

[0087] This embodiment provides a method for treating polyolefin catalyst waste liquid, including the following steps:

[0088] Sa, Preparation of titanium-containing organic waste liquid:

[0089] In a stirred five-necked flask fully purged with nitrogen, 10 g of polyolefin catalyst support MgClOEt and 80 mL of heptane were added to prepare a suspension. Then, 20 mL of titanium tetrachloride was added dropwise at -15 °C. After the addition was complete, the system was slowly heated to 10 °C, and 60 mL of titanium tetrachloride was added dropwise. The temperature was then slowly raised to 80 °C, and 3.5 g of 9,9-methoxymethylfluorene was added. The temperature was then raised to 120 °C and held for 2 hours. After pressure filtration, the first catalyst mother liquor and the first solid were obtained. The first solid was washed three times with 120 mL of titanium tetrachloride at 125 °C, and then washed twice with 150 mL of heptane at 60 °C and twice at room temperature. Solid-liquid separation was performed to obtain the first washing liquid and the second solid. The second solid was dried to obtain the Ziegler-Natta catalyst (analytical titanium content of 3.68 wt% and 9,9-methoxymethylfluorene content of 15.08 wt%).

[0090] The mixture of the first catalyst mother liquor and the first washing liquid was subjected to vacuum distillation to recover part of the solvent (heptane), yielding the first distillation residue, which is the titanium-containing organic waste liquid. Measurements showed that the titanium-containing organic waste liquid contained 9.1 wt% titanium, 24.9 wt% chlorine, 62.6 wt% heptane, and 0.5 wt% 9,9-methoxymethylfluorene.

[0091] Preparation of waste liquid containing organoaluminum compounds (Sb):

[0092] In a stirred five-necked flask fully purged with nitrogen, 300 mL of n-pentane, 20 mL of 0.5 mol / L diethylaluminum pentane solution, and 10 g of the above Ziegler-Natta catalyst were added. The mixture was kept at 5 °C for 5 min. Propylene was then introduced through a mass flow meter at a rate of 20 g / h. After reacting for 60 min, the propylene flow was stopped, and the mixture was filtered to obtain a second catalyst mother liquor and a third solid. The third solid was washed with n-pentane, and the solid and liquid were separated to obtain a second washing liquid and a fourth solid. The fourth solid was dried under vacuum to obtain 26.0 g of prepolymerization catalyst.

[0093] The mixture of the second catalyst mother liquor and the second washing liquid was subjected to vacuum distillation to recover part of the solvent (n-pentane), yielding the second distillation residue, which was the waste liquid containing organoaluminum compounds. Measurements showed that the waste liquid contained 4.2 wt% aluminum, 5.6 wt% chlorine, 0.3 wt% internal electron donor, and 78.1 wt% n-pentane.

[0094] In a stirred five-necked flask fully purged with nitrogen, 42.0 g of titanium-containing organic waste liquid (3.82 g titanium, 0.080 mol titanium) was added. Under stirring, 52.8 g of organic aluminum compound waste liquid (2.22 g aluminum, 0.082 mol aluminum) was gradually added. The reaction was carried out at 10 °C for 2.5 h. After cooling to room temperature, the mixture was filtered to obtain 12.3 g of titanium compound solid and low-titanium organic waste liquid.

[0095] Measurements showed that the titanium content in the low-titanium organic waste liquid was 0.8 wt%. It should be noted that during the redox reaction, the ethyl group in diethylaluminum chloride was converted into ethane and ethylene, which were emitted as gases.

[0096] Sd, low-titanium organic waste liquid was subjected to vacuum distillation to obtain organic solvent (22.1g heptane, 39.2g n-pentane) and 16.9g waste.

[0097] Example 5

[0098] This embodiment provides a method for treating polyolefin catalyst waste liquid, including the following steps:

[0099] Sa, Preparation of titanium-containing organic waste liquid:

[0100] In a stirred five-necked flask fully purged with nitrogen, 10 g of the polyolefin catalyst support MgClEt and 80 mL of dichloromethane were added to prepare a suspension. Then, 20 mL of titanium tetrachloride was added dropwise at -15 °C. After the addition was complete, the system was slowly heated to 10 °C, and then 60 mL of titanium tetrachloride was added dropwise. The temperature was then slowly increased to 80 °C, and 3.5 g of titanium tetrachloride was added. 2-Isopropyl-2-isopentyl-1,3-dimethoxypropane was heated to 120℃ and held for 2 hours, then filtered to obtain the first catalyst mother liquor and the first solid. The first solid was washed three times with 120 mL of titanium tetrachloride at 125℃, and then washed twice with 150 mL of dichloromethane at 60℃ and twice at room temperature. The solid and liquid were separated to obtain the first washing liquid and the second solid. The second solid was dried to obtain the Ziegler-Natta catalyst (analytical titanium content of 3.15 wt% and 2-isopropyl-2-isopentyl-1,3-dimethoxypropane content of 16.52 wt%).

[0101] The mixture of the first catalyst mother liquor and the first washing liquid was subjected to vacuum distillation to recover part of the solvent (dichloromethane), yielding the first distillation residue, which is the titanium-containing organic waste liquid. Measurements showed that the titanium-containing organic waste liquid contained 10.3 wt% titanium, 28.1 wt% chlorine, 53.6 wt% dichloromethane, and 0.7 wt% 2-isopropyl-2-isopentyl-1,3-dimethoxypropane.

[0102] Preparation of waste liquid containing organoaluminum compounds (Sb):

[0103] In a stirred five-necked flask fully purged with nitrogen, 300 mL of toluene, 20 mL of 0.5 mol / L propylaluminoxane toluene solution, and 10 g of the above Ziegler-Natta catalyst were added. After being kept at 5 °C for 5 min, propylene was introduced through a mass flow meter at a rate of 20 g / h. After reacting for 60 min, the propylene flow was stopped, and the mixture was filtered to obtain a second catalyst mother liquor and a third solid. The third solid was washed with toluene, and the solid and liquid were separated to obtain a second washing liquid and a fourth solid. The fourth solid was dried under vacuum to obtain 25.9 g of prepolymerization catalyst.

[0104] The mixture of the second catalyst mother liquor and the second washing liquid was subjected to vacuum distillation to recover part of the solvent (toluene), yielding the second distillation residue, which was the waste liquid containing organoaluminum compounds. Measurements showed that the waste liquid containing organoaluminum compounds contained 3.9 wt% aluminum, 0.7 wt% chlorine, 0.6 wt% internal electron donors, and 82.5 wt% toluene.

[0105] In a stirred five-necked flask fully purged with nitrogen, 37.2 g of titanium-containing organic waste liquid (3.83 g titanium, 0.080 mol titanium) was added. Under stirring, 79.2 g of organic aluminum compound waste liquid (3.09 g aluminum, 0.114 mol aluminum) was gradually added. The reaction was carried out at 95 °C for 10 min. After cooling to room temperature, the mixture was filtered to obtain 15.5 g of titanium-containing compound and low-titanium organic waste liquid.

[0106] Measurements showed that the titanium content in the low-titanium organic waste liquid was 0.22 wt%. It should be noted that during the redox reaction, the propyl group in propylaluminoxane is converted into propane and propylene, which are emitted in gaseous form.

[0107] Sd, low-titanium organic waste liquid was subjected to vacuum distillation to obtain organic solvent (59.7g toluene, 18.8g dichloromethane) and 19.3g waste.

[0108] Example 6

[0109] This embodiment provides a method for treating polyolefin catalyst waste liquid, including the following steps:

[0110] Sa, Preparation of titanium-containing organic waste liquid:

[0111] In a stirred five-necked flask fully purged with nitrogen, 10 g of polyolefin catalyst support Mg(Et)2 and 80 mL of cyclohexane were added to prepare a suspension. Then, 20 mL of titanium tetrachloride was added dropwise at -15 °C. After the addition was complete, the system was slowly heated to 10 °C, and 60 mL of titanium tetrachloride was added dropwise. The temperature was then slowly raised to 80 °C, and 3.5 g of di-n-butyl phthalate was added. The temperature was then raised to 120 °C and held for 2 hours. After pressure filtration, the first catalyst mother liquor and the first solid were obtained. The first solid was washed three times with 120 mL of titanium tetrachloride at 125 °C, and then washed twice with 150 mL of cyclohexane at 60 °C and twice at room temperature. Solid-liquid separation was performed to obtain the first washing liquid and the second solid. The second solid was dried to obtain the Ziegler-Natta catalyst (analytical titanium content of 3.31 wt% and di-n-butyl phthalate content of 12.07 wt%).

[0112] The mixture of the first catalyst mother liquor and the first washing liquid was used as the titanium-containing organic waste liquid. Measurements showed that the titanium-containing organic waste liquid contained 8.9 wt% titanium, 25.4 wt% chlorine, 62.3 wt% cyclohexane, and 0.5 wt% di-n-butyl phthalate.

[0113] Preparation of waste liquid containing organoaluminum compounds (Sb):

[0114] In a stirred five-necked flask fully purged with nitrogen, 300 mL of cyclohexane, 20 mL of 0.5 mol / L tri-n-butylaluminum cyclohexane solution, and 10 g of the above Ziegler-Natta catalyst were added. After being kept at 5 °C for 5 min, propylene was introduced through a mass flow meter at a rate of 20 g / h. After reacting for 60 min, the propylene flow was stopped, and the mixture was filtered to obtain a second catalyst mother liquor and a third solid. The third solid was washed with cyclohexane, and the solid and liquid were separated to obtain a second washing liquid and a fourth solid. The fourth solid was dried under vacuum to obtain 26.2 g of prepolymerization catalyst.

[0115] The mixture of the second catalyst mother liquor and the second washing liquid was used as the waste liquid containing organoaluminum compounds. Measurements showed that the waste liquid containing organoaluminum compounds contained 5.3 wt% aluminum, 0.9 wt% chlorine, 0.4 wt% internal electron donors, and 70.1 wt% cyclohexane.

[0116] In a stirred five-necked flask fully purged with nitrogen, 43.0 g of titanium-containing organic waste liquid (3.83 g titanium, 0.080 mol titanium) was added. Under stirring, 326.1 g of organic aluminum compound waste liquid (17.28 g aluminum, 0.64 mol aluminum) was gradually added. The reaction was carried out at 80 °C for 30 min. After cooling to room temperature, the mixture was filtered to obtain 15.3 g of titanium-containing compound and low-titanium organic waste liquid.

[0117] Measurements showed that the titanium content in the low-titanium organic waste liquid was 0.03 wt%. It should be noted that during the redox reaction, the n-butyl group in tri-n-butylaluminum is converted into butane and butene, which are emitted in gaseous form.

[0118] Sd, low-titanium organic waste liquid was subjected to vacuum distillation to obtain organic solvent (77.8g cyclohexane) and 202.4g waste.

[0119] Comparative Example 1

[0120] This comparative example provides a method for treating titanium-containing organic waste liquid, including the following steps:

[0121] Sa, preparation of titanium-containing organic waste liquid: same as Sb in Example 1, and will not be repeated.

[0122] Sb, 40g of titanium-containing organic waste liquid (3.84g titanium, 0.080mol titanium) was slowly poured into 500mL of room temperature water and stirred rapidly until hydrolysis was complete. Then, 9.17g of calcium oxide was added in batches under stirring. The reaction was carried out at 60℃ for 2h, cooled to room temperature, and filtered to obtain 27.6g of paste, 485g of aqueous phase and 33g of organic phase.

[0123] Comparative Example 2

[0124] This comparative example provides a method for treating titanium-containing organic waste liquid, including the following steps:

[0125] Sa, preparation of titanium-containing organic waste liquid: same as Sb in Example 1, and will not be repeated.

[0126] Sb, 40g of titanium-containing organic waste liquid (3.84g titanium, 0.080mol titanium) was slowly poured into 500mL of room temperature water and stirred rapidly until hydrolysis was complete. Then, 13.0g of sodium hydroxide was added in batches under stirring and reacted at 60℃ for 2h (the reaction equations can be found in Equations 3 and 4). After cooling to room temperature, the mixture was filtered to obtain 25.5g of paste, 490g of aqueous phase and 28g of organic phase.

[0127] Formula 3

[0128] Formula 4

[0129] In Formula 4, R is the alkyl group corresponding to alkoxytitanium chloride.

[0130] As can be seen from the test data of the above examples and comparative examples, titanium in titanium-containing organic waste liquid exists in the form of titanium tetrachloride, alkoxy titanium chloride, etc. Neutralization treatment of the hydrolysate of titanium-containing organic waste liquid with inorganic alkali yields three products: a paste, an aqueous phase, and an organic phase. The paste is mainly the hydrolysate of titanium tetrachloride (titanium dioxide), and also contains impurities such as inorganic salts and excess alkali, which can be further recycled. The organic phase is an organic solvent containing high-boiling-point substances. The aqueous phase is mainly an aqueous solution containing inorganic salts and excess alkali, such as an aqueous solution containing small amounts of sodium hydroxide, sodium chloride, and magnesium chloride. Both the aqueous and organic phases require further treatment, but the above measures increase costs and cannot achieve the effect of treating waste liquid containing organometallic compounds as described in this invention, which significantly improves the recovery rate of titanium and the recovery rate of organic solvents in titanium-containing organic waste liquid.

[0131] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for treating polyolefin catalyst waste liquid, characterized in that: Includes the following steps: S1, under an inert atmosphere, titanium-containing organic waste liquid and waste liquid containing organometallic compounds are subjected to an oxidation-reduction reaction, and solid-liquid separation is performed to obtain titanium-containing compounds and low-titanium organic waste liquid. The titanium-containing organic waste liquid is a waste liquid containing tetravalent titanium generated during the preparation of titanium-based polyolefin catalysts; the titanium-containing organic waste liquid includes titanium tetrachloride, alkoxy titanium chloride, internal electron donor, magnesium chloride powder and a first organic solvent; The waste liquid containing organometallic compounds includes at least one of waste liquid containing organoaluminum compounds or waste liquid containing organomagnesium compounds; the waste liquid containing organoaluminum compounds includes organoaluminum compounds, and the waste liquid containing organomagnesium compounds includes organomagnesium compounds; the organoaluminum compounds include at least one of alkylaluminum, chloroalkylaluminum, or aluminumoxane, and the organomagnesium compounds include at least one of alkylmagnesium or alkylchloromagnesium. The organoaluminum compounds and organomagnesium compounds reduce titanium in the titanium-containing organic waste liquid from tetravalent to trivalent and divalent, respectively, and the corresponding material state changes from liquid to solid, thus precipitating out of the organic waste liquid; S2, the low-titanium organic waste liquid is distilled to obtain organic solvent and waste.

2. The method for treating polyolefin catalyst waste liquid as described in claim 1, characterized in that: In S1, the waste liquid containing organoaluminum compounds includes an organoaluminum compound, an internal electron donor, and a second organic solvent; the waste liquid containing organomagnesium compounds includes an organomagnesium compound and a third organic solvent.

3. The method for treating polyolefin catalyst waste liquid as described in claim 2, characterized in that: In S1, the alkoxy titanium chloride includes at least one of methoxy titanium trichloride, ethoxy titanium trichloride, propoxy titanium trichloride, n-butoxy titanium trichloride, dimethoxy titanium dichloride, diethoxy titanium dichloride, dipropoxy titanium dichloride, di-n-butoxy titanium dichloride, trimethoxy titanium chloride, triethoxy titanium chloride, tripropoxy titanium chloride, or tri-n-butoxy titanium chloride. In S1, the internal electron donor includes at least one of diether compounds, aromatic dicarboxylic acid ester compounds, succinate compounds, aromatic diol ester compounds, aliphatic diol ester compounds, or amine compounds; In S1, the first organic solvent includes at least one of toluene, benzene, n-hexane, cyclohexane, heptane, dichloromethane, or chloroform.

4. The method for treating polyolefin catalyst waste liquid as described in claim 2, characterized in that: In S1, the second organic solvent includes at least one of n-pentane, n-hexane, n-heptane, n-octane, cyclohexane, toluene, ethylbenzene, or xylene; In S1, the third organic solvent includes at least one of n-pentane, n-hexane, n-heptane, n-octane, cyclohexane, toluene, ethylbenzene, or xylene.

5. The method for treating polyolefin catalyst waste liquid as described in claim 4, characterized in that: In S1, the alkylaluminum includes at least one of triethylaluminum, tributylaluminum, triisobutylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum, or isoprene aluminum; In S1, the chloroalkyl aluminum includes at least one of diethylaluminum chloride, diethylaluminum chloride, or sesquiethylaluminum. In S1, the aluminum oxane is at least one of methyl aluminum oxane, modified methyl aluminum oxane, ethyl aluminum oxane, propyl aluminum oxane, or butyl aluminum oxane. In S1, the alkyl magnesium includes at least one of dimethyl magnesium, diethyl magnesium, dipropyl magnesium, dibutyl magnesium, dihexyl magnesium, dioctyl magnesium, ethylbutyl magnesium, butylhexyl magnesium, butyloctyl magnesium, methylphenyl magnesium, or ethylphenyl magnesium. In S1, the alkyl magnesium chloride includes at least one of methyl magnesium chloride, ethyl magnesium chloride, propyl magnesium chloride, butyl magnesium chloride, or phenyl magnesium chloride.

6. The method for treating polyolefin catalyst waste liquid as described in claim 2, characterized in that: In S1, the titanium-containing organic waste liquid includes at least one of the first catalyst mother liquor, the first washing liquid, or the first distillation residue generated during the preparation of titanium-based polyolefin catalyst; In S1, the waste liquid containing organoaluminum compounds includes at least one of the second catalyst mother liquor, the second washing liquid, or the second distillation residue generated during the preparation of the prepolymerization catalyst; In S1, the waste liquid containing organic magnesium compounds includes waste liquid containing organic magnesium compounds generated during the preparation of polyolefin catalysts.

7. The method for treating polyolefin catalyst waste liquid as described in claim 6, characterized in that: In S1, the first distillation residue is the residue after the first catalyst mother liquor and / or the first washing liquid have been distilled to remove part of the first organic solvent. In S1, the second distillation residue is the residue after the second catalyst mother liquor and / or the second washing liquid have been distilled to remove part of the second organic solvent.

8. The method for treating polyolefin catalyst waste liquid according to any one of claims 2 to 7, characterized in that: In S1, the titanium-containing organic waste liquid contains 5wt%~15wt% titanium, 20wt%~35wt% chlorine, 0.1wt%~3wt% internal electron donor, ≤5wt% magnesium chloride powder, and 50wt%~90wt% first organic solvent. In S1, the aluminum content in the waste liquid containing organoaluminum compounds is 2wt%~10wt%, the chlorine content is ≤5wt%, the content of internal electron donors is ≤2wt%, and the content of the second organic solvent is 65wt%~95wt%. In S1, the magnesium content in the waste liquid containing organic magnesium compounds is 5wt%~15wt%, the chlorine content is 5wt%~25wt%, and the content of the third organic solvent is 50wt%~90wt%.

9. The method for treating polyolefin catalyst waste liquid according to any one of claims 1 to 7, characterized in that: In S1, the molar ratio of titanium in the titanium-containing organic waste liquid to the metal in the waste liquid containing organometallic compounds is 1:(0.1~30); In S1, the temperature of the redox reaction is 0℃~100℃, and the reaction time is 1min~150min.

10. The method for treating polyolefin catalyst waste liquid according to any one of claims 1 to 7, characterized in that: In S1, the titanium-containing compound includes at least three of titanium dichloride, titanium trichloride, low-valent alkoxy titanium chloride, or low-valent alkoxy titanium. The low-valent alkoxy titanium chloride includes at least one of methoxy titanium dichloride, ethoxy titanium dichloride, propoxy titanium dichloride, n-butoxy titanium dichloride, dimethoxy titanium monochloride, diethoxy titanium monochloride, dipropoxy titanium monochloride, or di-n-butoxy titanium monochloride; The low-valent alkoxy titanium includes at least one of trimethoxy titanium, triethoxy titanium, tripropoxy titanium, or tri-n-butoxy titanium; In S1, the titanium content in the low-titanium organic waste liquid is ≤3.0wt%.