ZN type catalytic filtrate separation and recovery system and method

Abstract

The present invention provides a separation and recovery system and method for Z-N type catalyst filtrate. The separation and recovery system of the Z-N type catalyst filtrate provided in the present application includes an evaporation separation unit, a toluene separation unit, a titanium tetrachloride separation unit and a residual liquid treatment unit, wherein the evaporation unit includes a first evaporation kettle, the toluene separation unit includes a toluene distillation tower, the titanium tetrachloride unit includes a titanium tetrachloride distillation tower, and the residual liquid treatment unit includes an alkalization kettle. The separation and recovery system of the Z-N type catalyst filtrate provided in the present application, by the evaporation separation unit, the toluene separation unit, the titanium tetrachloride separation unit and the residual liquid unit, not only can toluene and titanium tetrachloride be recovered, but also the first evaporating liquid and the second evaporating liquid can be continued to be recycled, effectively reducing energy waste, reducing the recovery cost of the Z-N type catalyst filtrate, thereby improving economy and environmental protection, and having broad application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of waste liquid recovery and treatment, and in particular to a separation and recovery system and method for a ZN type catalyst filtrate. Background Art

[0002] Currently, the main polypropylene catalyst used in industry is the Ziegler-Natta (ZN) catalyst, which consists of a main catalyst and a co-catalyst. The main catalyst is composed of titanium tetrachloride and a titanium-loaded support. The preparation process of ZN-type polypropylene catalysts has problems such as high solvent consumption and low raw material conversion per pass. This results in a large amount of catalyst filtrate. If the raw materials and solvent are not separated and recovered, the cost of the catalyst product will be greatly increased, which is not economical. In addition, the large amount of residual liquid is not conducive to environmental protection. Therefore, the effective separation and recovery of the catalyst filtrate during the catalyst preparation process is of great significance.

[0003] Currently, the separation and recovery of ZN catalyst filtrate mainly involves filtration treatment or converting titanium chloride in the filtrate into hydrochloric acid for recovery, without separating and recovering the related solvents, resulting in a large amount of energy being wasted and poor economic and environmental performance.

[0004] In view of this, the present invention is proposed. Summary of the Invention

[0005] The main purpose of the present invention is to provide a ZN type catalytic filtrate separation and recovery system and method to solve the problem that the separation and recovery of ZN catalyst filtrate in the prior art mainly involves filtration treatment or converting titanium chloride in the filtrate into hydrochloric acid for recovery, without separating and recovering the related solvent, resulting in a large amount of energy being wasted and poor economic and environmental performance.

[0006] To achieve the above objectives, according to one aspect of the present invention, a separation and recovery system for a ZN catalyst filtrate is provided. The separation and recovery system comprises: an evaporation separation unit, a toluene separation unit, a titanium tetrachloride separation unit, and a residual liquid treatment unit. The evaporation separation unit comprises a first evaporator, the first evaporator being used to evaporate and separate the ZN catalyst filtrate to obtain a second evaporated liquid and a residual liquid; the toluene separation unit comprises a toluene distillation tower connected to the first evaporator and used to distill and separate the first evaporated liquid to obtain toluene and a first heavy component; the titanium tetrachloride separation unit comprises a titanium tetrachloride distillation tower connected to the toluene distillation tower and used to distill and separate the first heavy component to obtain titanium tetrachloride and a second heavy component; the titanium tetrachloride distillation tower is also connected to the first evaporator and used to return the second heavy component to the first evaporator; and the residual liquid treatment unit comprises an alkalization kettle, the alkalization kettle being used to sequentially perform a second evaporation separation and alkalization treatment on the residual liquid to obtain a second evaporated liquid and an alkalized mixed liquid, and the alkalization kettle is connected to the first evaporator and used to return the second evaporated liquid to the first evaporator.

[0007] Furthermore, the residual liquid processing unit also includes a hydrocyclone separator, an oil-water separator, a second evaporation kettle and a decane / isooctanol distillation tower connected in sequence. The hydrocyclone separator is connected to the alkalization kettle and is used to separate the solid and liquid of the alkalized mixed liquid to obtain a solid by-product and an alkalized liquid; the oil-water separator is used to separate the water and oil of the alkalized liquid to obtain an aqueous phase liquid and an oily phase liquid; the second evaporation kettle is used to evaporate and separate the oily phase liquid to obtain a crude decane / isooctanol product and a first waste liquid; and the decane / isooctanol distillation tower is used to distill and separate the crude decane / isooctanol product to obtain decane / isooctanol and a second waste liquid.

[0008] Furthermore, the residual liquid treatment unit also includes a drying tower, which is connected to the decane / isooctanol distillation tower and is used to dry the decane / isooctanol; a first condenser is also provided on the pipeline between the decane / isooctanol distillation tower and the drying tower, and the first condenser is used to condense the decane / isooctanol.

[0009] Furthermore, the toluene separation unit also includes a second condenser, which is arranged at the top of the toluene distillation tower and connected to the toluene distillation tower for condensing toluene; the titanium tetrachloride separation unit also includes a third condenser, which is arranged at the top of the titanium tetrachloride distillation tower and connected to the titanium tetrachloride distillation tower for condensing titanium tetrachloride; a fourth condenser is provided on the pipeline between the alkalization kettle and the first evaporation kettle, and the fourth condenser is used to condense the second evaporated liquid. To achieve the above-mentioned object, according to another aspect of the present invention, a method for separating and recovering a ZN-type catalyst is provided. The method comprises: step S1, subjecting a ZN-type catalyst filtrate to a first evaporation separation to obtain a first evaporation liquid and a residual liquid; step S2, subjecting the first evaporation liquid to a first rectification separation to obtain toluene and a first heavy component; step S3, subjecting the first heavy component to a second rectification separation to obtain titanium tetrachloride and a second heavy component, wherein the second heavy component is returned to step S1, mixed with the ZN-type catalyst filtrate, and further subjected to the first evaporation separation; and step S4, subjecting the residual liquid to a second evaporation separation and an alkalization treatment in sequence to obtain a second evaporation liquid and an alkalized product mixed liquid, wherein the second evaporation liquid is returned to step S1, mixed with the ZN-type catalyst filtrate, and further subjected to the first evaporation separation.

[0010] Furthermore, step S4 also includes separation and recovery of the alkalized mixed liquid, which includes: step S41, performing solid-liquid separation on the alkalized mixed liquid to obtain a solid by-product and an alkalized liquid; step S42, performing water-oil separation on the alkalized liquid to obtain an aqueous phase liquid and an oil phase liquid; step S43, performing a second evaporation separation on the oil phase liquid to obtain a crude decane / isooctanol product and a first waste liquid; step S44, performing a third distillation separation on the crude decane / isooctanol product to obtain decane / isooctanol and a second waste liquid.

[0011] Furthermore, the third distillation separation is vacuum distillation, with a temperature of 110 to 160° C. and a pressure of -0.08 to 0 MPa.

[0012] Furthermore, step S4 further includes: sequentially performing condensation treatment and drying treatment on the decane / isooctanol.

[0013] Furthermore, step S further includes condensation of toluene; step S3 further includes condensation of titanium tetrachloride; and step S4 further includes condensation of the second evaporating liquid.

[0014] Furthermore, in step S1, the temperature of the first evaporation separation is 130-150°C.

[0015] Furthermore, the first distillation separation is atmospheric distillation separation, and the temperature thereof is 105-135°C.

[0016] Furthermore, the second distillation separation is atmospheric distillation separation, and the temperature thereof is 130-155°C.

[0017] Furthermore, the temperature of the second evaporation separation is 120-200°C.

[0018] Furthermore, calculated by mass percentage, the ZN-type catalyst filtrate includes 0.5-42.67% toluene, 42.67-85.34% titanium tetrachloride, 0.5-0.6% tetrabutyl titanate, 0.78-0.9% electron donor, 4.1-4.9% decane, 8.2-8.9% alcoholated titanium trichloride, and 0.02-0.05% catalyst fine powder.

[0019] By applying the technical solution of the present application, the ZN-type catalyst filtrate separation and recovery system provided in the present application, through an evaporation separation unit, a toluene separation unit, a titanium tetrachloride separation unit, and a residual liquid unit, can not only recover toluene and titanium tetrachloride, but also can continue to circulate and recycle the first evaporated liquid and the second evaporated liquid, effectively reducing energy waste and lowering the recovery cost of the ZN-type catalyst filtrate, thereby improving economy and environmental protection, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0021] Figure 1 The schematic flow diagram of the ZN catalyst filtrate separation and recovery system provided in Example 1 of the present invention is shown.

[0022] The above drawings include the following reference numerals:

[0023] 11. First evaporator; 21. Toluene distillation tower; 22. Second condenser; 31. Titanium tetrachloride distillation tower; 32. Third condenser; 41. Alkalization kettle; 42. Hydrocyclone; 43. Oil-water separator; 44. Second evaporator; 45. Decane / isooctanol distillation tower; 46. First condenser; 47. Drying tower; 48. Fourth condenser. DETAILED DESCRIPTION

[0024] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0025] As analyzed in the background technology of this application, the current separation and recovery of ZN catalyst filtrate mainly involves filtration treatment or converting the titanium chloride in the filtrate into hydrochloric acid for recovery, and the relevant solvents are not separated and recovered. This results in a large amount of energy being wasted, and the economy and environmental protection are poor. In order to solve this problem, this application provides a separation and recovery system and method for ZN catalyst filtrate.

[0026] In a typical embodiment of the present application, a separation and recovery system for a ZN type catalyst filtrate is provided, such as Figure 1 As shown, the separation and recovery system includes: an evaporation separation unit, a toluene separation unit, a titanium tetrachloride separation unit and a residual liquid processing unit. The evaporation separation unit includes a first evaporation kettle 11, which is used to evaporate and separate the ZN catalyst filtrate to obtain a second evaporated liquid and a residual liquid; the toluene separation unit includes a toluene distillation tower 21, which is connected to the first evaporation kettle 11 and is used to distill and separate the first evaporated liquid to obtain toluene and a first heavy component; the titanium tetrachloride separation unit includes a titanium tetrachloride distillation tower 31, which is used to distill and separate the first evaporated liquid to obtain toluene and a first heavy component. The tower 31 is connected to the toluene distillation tower 21 and is used to distill and separate the first heavy component to obtain titanium tetrachloride and a second heavy component. The titanium tetrachloride distillation tower 31 is also connected to the first evaporation kettle 11 and is used to return the second heavy component to the first evaporation kettle 11. The residual liquid processing unit includes an alkalization kettle 41. The alkalization kettle 41 is used to sequentially perform a second evaporation treatment and an alkalization treatment on the residual liquid to obtain a second evaporated liquid and an alkalized product mixed liquid. The alkalization kettle 41 is connected to the first evaporator and is used to return the second evaporated liquid to the first evaporation kettle 11.

[0027] By applying the technical solution of the present application, the ZN-type catalyst filtrate separation and recovery system provided in the present application, through an evaporation separation unit, a toluene separation unit, a titanium tetrachloride separation unit, and a residual liquid unit, can not only recover toluene and titanium tetrachloride, but also can continue to circulate and recycle the first evaporated liquid and the second evaporated liquid, effectively reducing energy waste and lowering the recovery cost of the ZN-type catalyst filtrate, thereby improving economy and environmental protection, and has broad application prospects.

[0028] In order to further improve the energy recovery and utilization rate, the residual liquid treatment unit preferably also includes a hydrocyclone 42, an oil-water separator 43, a second evaporation kettle 44 and a decane / isooctanol distillation tower 45 connected in sequence, wherein the hydrocyclone 42 is connected to the alkalization kettle 41 for performing solid-liquid separation on the alkalized mixed liquid to obtain a solid by-product (mainly titanium dioxide) and an alkalized liquid; the oil-water separator 43 is connected to the hydrocyclone 42 for performing water-oil separation on the alkalized liquid to obtain an aqueous phase liquid and an oil phase liquid, and the aqueous phase liquid is sent to a water treatment system for centralized treatment; the second evaporation kettle 44 is used to evaporate and separate the oil phase liquid to obtain a crude decane / isooctanol product and a first waste liquid; the decane / isooctanol distillation tower 45 is connected to the second evaporation kettle 44 for distilling and separating the crude decane / isooctanol product to obtain decane / isooctanol and a second waste liquid, and the first waste liquid and the second waste liquid are collected and centrally treated, thereby reducing environmental pollution while recovering the decane / isooctanol.

[0029] In this application, decane refers to n-decane, and decane / isooctanol refers to n-decane and isooctanol.

[0030] In order to further reduce the moisture in decane / isooctanol, the residual liquid treatment unit preferably further includes a drying tower 47, which is connected to the decane / isooctanol distillation tower 45 for drying the decane / isooctanol to further improve the product quality of the decane / isooctanol.

[0031] In order to further reduce the difficulty of the drying process, a first condenser 46 is preferably provided on the pipeline between the decane / isooctanol distillation tower 45 and the drying tower 47. The first condenser 46 is used to condense the gaseous decane / isooctanol separated by the decane / isooctanol distillation tower 45 into liquid decane / isooctanol and then transport it to the drying tower 47 for drying treatment.

[0032] In order to facilitate the storage of toluene, the toluene separation unit preferably also includes a second condenser 22, which is arranged at the top of the toluene distillation tower 21 and connected to the toluene distillation tower 21, and is used to condense the gaseous toluene separated by the toluene distillation tower 21 into liquid toluene for storage.

[0033] In order to facilitate the storage of titanium tetrachloride, the titanium tetrachloride separation unit preferably further includes a third condenser 32. The third condenser 32 is arranged at the top of the titanium tetrachloride distillation tower 31, and the third condenser 32 is connected to the titanium tetrachloride distillation tower 31, and is used to condense the gaseous titanium tetrachloride separated by the titanium tetrachloride distillation tower 31 into liquid titanium tetrachloride for storage.

[0034] In order to facilitate the recycling of the second evaporated liquid, a fourth condenser 48 is preferably provided on the pipeline between the alkalization kettle 41 and the first evaporation kettle 11. The fourth condenser 48 is used to condense the gaseous second evaporated liquid evaporated from the alkalization kettle 41 into liquid second evaporated liquid and return it to the first evaporation kettle 11 for recycling.

[0035] In a second typical embodiment of the present application, a separation and recovery method for a ZN-type catalyst filtrate is further provided. The separation and recovery method comprises: step S1, performing a first evaporation separation on the ZN-type catalyst filtrate to obtain a first evaporated liquid and a residual liquid; step S2, performing a first distillation separation on the first evaporated liquid to obtain toluene and a first heavy component; step S3, performing a second distillation separation on the first heavy component to obtain titanium tetrachloride and a second heavy component, and the second heavy component is returned to step S1 and mixed with the ZN-type catalyst filtrate to continue the first evaporation separation and recycling; step S4, performing a second evaporation separation and alkalization treatment on the residual liquid in sequence to obtain a second evaporated liquid and an alkalized mixed liquid, and the second evaporated liquid is returned to step S1 and mixed with the ZN-type catalyst filtrate to continue the first evaporation separation.

[0036] The present application provides a method for separating and recovering a ZN-type catalyst filtrate, wherein the ZN-type catalyst filtrate is sequentially subjected to a first evaporation separation, a first distillation separation, and a second distillation separation, and the residual liquid obtained by the first evaporation separation is sequentially subjected to a second evaporation separation and an alkalization treatment. This method not only recovers toluene and titanium tetrachloride, but also allows the first evaporated liquid and the second evaporated liquid to be further recycled and utilized, effectively reducing energy waste and lowering the recovery cost of the ZN-type catalyst filtrate, thereby improving economy and environmental protection, and having broad application prospects.

[0037] The above-mentioned ZN-type catalyst filtrate is the filtrate obtained during the preparation of ZN-type catalyst in the art. Its specific components are not specifically limited, including but not limited to toluene, titanium tetrachloride, tetrabutyl titanate, electron donor, n-decane, alcoholated titanium trichloride, catalyst fine powder, etc.

[0038] In the present application, the electron donor includes at least one of phthalate compounds, salicylate compounds, fluorene diether compounds, succinate compounds or glycol compounds; wherein, phthalate compounds include but are not limited to diisobutyl phthalate, di-n-butyl phthalate, etc.; salicylate compounds include but are not limited to isobutyl o-benzoyloxybenzoate, n-butyl 3-methyl-2-benzoyloxybenzoate; fluorene diether compounds include but are not limited to 9,9-bis(methoxymethyl)fluorene, 2,4-dimethyl 3,3-bis(methoxymethyl)pentane; succinate compounds include but are not limited to dibutyl 2,3-diisopropylsuccinate, diethyl 2,3-diisopropylsuccinate; glycol compounds include but are not limited to 1,3-propylene glycol benzoate, 1,3-pentanediol benzoate.

[0039] In some embodiments of the present application, the ZN-type catalyst filtrate includes, by mass percentage, 0.5-42.67% toluene, 42.67-85.34% titanium tetrachloride, 0.5-0.6% tetrabutyl titanate, 0.78-0.9% electron donor, 4.1-4.9% decane, 8.2-8.9% alcoholated titanium trichloride, and 0.02-0.05% catalyst fine powder.

[0040] Typically but not limiting, in the ZN catalyst filtrate, the mass content of toluene is such as 0.5%, 1%, 2%, 5%, 10%, 15%, 20%, 30%, 40%, 42.67% or a range consisting of any two values; the mass content of titanium tetrachloride is such as 42.67%, 45%, 50%, 55%, 60%, 70%, 80%, 85.34% or a range consisting of any two values; the mass content of tetrabutyl titanate is such as 0.5%, 0.52%, 0.55%, 0.58%, 0.6% or a range consisting of any two values; the mass content of electron donor is such as 0.7 the mass content of decane is such as 4.1%, 4.2%, 4.3%, 4.4%, 4.56%, 4.8%, 4.9% or a range consisting of any two numerical values; the mass content of alkoxide titanium trichloride is such as 8.2%, 8.3%, 8.4%, 8.5%, 8.69%, 8.7%, 8.8%8.9% or a range consisting of any two numerical values; the mass content of catalyst fine powder is such as 0.02%, 0.03%, 0.04%, 0.05% or a range consisting of any two numerical values.

[0041] In order to further improve the efficiency of the alkalization treatment, the alkalization treatment preferably includes: mixing the alkali solution with the solid matter after the second evaporation treatment, performing an alkalization reaction, and obtaining an alkalized mixed liquid, wherein the alkalized mixed liquid includes but is not limited to titanium dioxide, sodium chloride, water, decane, isooctyl alcohol, an electron donor, catalyst fine powder, etc.

[0042] When the alkali solution is sodium hydroxide solution, the alkalization reaction includes but is not limited to:

[0043] TICl4+NaOH→TiO2+NaCl+H2O

[0044] Ti(OC4H9)4+H2O→TiO2+C4H9OH

[0045] Ti(OC8H 17 )Cl3+H2O→TiO2+C8H 17 OH

[0046] In order to further recycle the residual liquid, step S4 preferably also includes separation and recovery of the alkalized mixed liquid, which includes: step S41, performing solid-liquid separation on the alkalized mixed liquid to obtain a solid by-product (the main component is titanium dioxide) and an alkalized liquid; step S42, performing water-oil separation on the alkalized liquid to obtain an aqueous phase liquid and an oil phase liquid, and the aqueous phase liquid is sent to a water treatment system for centralized treatment; step S43, performing a second evaporation separation on the oil phase liquid to obtain a crude decane / isooctanol product and a first waste liquid; step S44, performing a third distillation separation on the crude decane / isooctanol product to obtain decane / isooctanol and a second waste liquid, and the first waste liquid and the second waste liquid are collected separately for centralized treatment to improve environmental safety.

[0047] In order to further improve the distillation separation efficiency of the crude decane / isooctanol product, the third distillation separation is preferably performed as a vacuum distillation, which is performed in the decane / isooctanol distillation tower 45. Preferably, the top of the tower is cooled and refluxed by circulating water, and the temperature is controlled at 110 to 160° C. and the pressure is -0.08 to 0 MPa.

[0048] In order to further reduce the moisture content in decane / isooctanol, step S4 preferably also includes condensing and drying the decane / isooctanol in sequence, so as to condense the gaseous decane / isooctanol obtained by the third distillation separation into liquid decane / isooctanol and perform drying to remove the moisture content in the decane / isooctanol, so as to further improve the product quality of the decane / isooctanol.

[0049] In order to facilitate the storage of toluene, preferably step S2 further includes a condensation process of toluene, so as to condense the gaseous toluene separated by the first distillation into liquid toluene for storage.

[0050] In order to facilitate the storage of titanium tetrachloride, step S3 preferably further includes a condensation process of titanium tetrachloride, so as to condense the gaseous titanium tetrachloride separated by the second distillation into liquid titanium tetrachloride for storage.

[0051] In order to facilitate the recycling of the second evaporating liquid, step S4 preferably further includes condensation of the second evaporating liquid, so as to condense the gaseous second evaporating liquid separated by the second evaporation into liquid second evaporating liquid and return it to step S1 for recycling.

[0052] In order to further improve the efficiency of the first evaporation separation, the temperature of step S1 is preferably 130-150° C., and the evaporation process is stopped when solid appears in the ZN-type catalyst filtrate. The unevaporated filtrate is the residual liquid.

[0053] In order to further improve the separation efficiency of the first distillation separation, the first distillation separation is preferably performed as atmospheric distillation separation in a toluene distillation tower 21, with a distillation temperature of 105 to 135°C. The top of the tower is preferably cooled and refluxed by circulating water, and the temperature is controlled at 105 to 120°C, and the bottom of the tower is heated by steam, and the temperature is controlled at 110 to 135°C.

[0054] In order to further improve the separation efficiency of the second distillation separation, the second distillation separation is preferably carried out as atmospheric distillation separation in titanium tetrachloride distillation, and the distillation temperature is 130-155°C. Preferably, the top of the tower is cooled and refluxed by circulating water, and the temperature is controlled at 130-150°C, and the bottom of the tower is heated by steam, and the temperature is controlled at 135-155°C.

[0055] In order to improve the separation efficiency of the second evaporation separation, the temperature of the second evaporation separation is preferably 120-200°C.

[0056] The beneficial effects of the present application will be further illustrated below with reference to examples and comparative examples.

[0057] Example 1

[0058] like Figure 1As shown, this embodiment provides a separation and recovery system for a ZN type catalyst filtrate, which includes: an evaporation separation unit, a toluene separation unit, a titanium tetrachloride separation unit, and a residual liquid processing unit. The evaporation separation unit includes a first evaporation kettle 11, which is used to evaporate and separate the ZN catalyst filtrate to obtain a second evaporated liquid and a residual liquid; the toluene separation unit includes a toluene distillation tower 21, which is connected to the first evaporation kettle 11 and is used to distill and separate the first evaporated liquid to obtain toluene and a first heavy component; the titanium tetrachloride separation unit includes a titanium tetrachloride distillation tower 21. A titanium tetrachloride distillation tower 31 is connected to the toluene distillation tower 21 and is used to distill and separate the first heavy component to obtain titanium tetrachloride and a second heavy component. The titanium tetrachloride distillation tower 31 is also connected to the first evaporation kettle 11 and is used to return the second heavy component to the first evaporation kettle 11; a residual liquid processing unit includes an alkalization kettle 41, which is used to sequentially perform a second evaporation treatment and an alkalization treatment on the residual liquid to obtain a second evaporated liquid and an alkalized product mixed liquid. The alkalization kettle 41 is connected to the first evaporator and is used to return the second evaporated liquid to the first evaporation kettle 11.

[0059] To further improve the energy recovery and utilization rate, the residual liquid treatment unit also includes a hydrocyclone 42, an oil-water separator 43, a second evaporation kettle 44 and a decane / isooctanol distillation tower 45 connected in sequence. The hydrocyclone 42 is connected to the alkalization kettle 41 for performing solid-liquid separation on the alkalized mixture to obtain a solid byproduct (mainly titanium dioxide) and an alkalized liquid; the oil-water separator 43 is connected to the hydrocyclone 42 for performing water-oil separation on the alkalized liquid to obtain an aqueous phase liquid and an oil phase liquid, which is sent to a water treatment system for centralized treatment; the second evaporation kettle 44 is used to evaporate and separate the oil phase liquid to obtain a crude decane / isooctanol product and a first waste liquid; and the decane / isooctanol distillation tower 45 is connected to the second evaporation kettle 44 for distilling and separating the crude decane / isooctanol product to obtain decane / isooctanol and a second waste liquid. The first waste liquid and the second waste liquid are collected and centrally treated, thereby reducing environmental pollution while recovering the decane / isooctanol.

[0060] In order to further reduce the moisture in decane / isooctanol, the residual liquid processing unit further includes a drying tower 47, which is connected to the decane / isooctanol distillation tower 45 and is used to dry the decane / isooctanol to further improve the product quality of the decane / isooctanol.

[0061] In order to further reduce the difficulty of the drying process, a first condenser 46 is provided on the pipeline between the decane / isooctanol distillation tower 45 and the drying tower 47. The first condenser 46 is used to condense the gaseous decane / isooctanol separated by the decane / isooctanol distillation tower 45 into liquid decane / isooctanol and then transport it to the drying tower 47 for drying treatment.

[0062] In order to facilitate the storage of toluene, the toluene separation unit also includes a second condenser 22, which is arranged at the top of the toluene distillation tower 21 and connected to the toluene distillation tower 21, and is used to condense the gaseous toluene distilled and separated by the toluene distillation tower 21 into liquid toluene for storage.

[0063] In order to facilitate the storage of titanium tetrachloride, the titanium tetrachloride separation unit also includes a third condenser 32, which is arranged at the top of the titanium tetrachloride distillation tower 31. The third condenser 32 is connected to the titanium tetrachloride distillation tower 31 and is used to condense the gaseous titanium tetrachloride separated by the titanium tetrachloride distillation tower 31 into liquid titanium tetrachloride for storage.

[0064] In order to facilitate the recycling of the second evaporated liquid, a fourth condenser 48 is provided on the pipeline between the alkalization kettle 41 and the first evaporation kettle 11. The fourth condenser 48 is used to condense the gaseous second evaporated liquid evaporated from the alkalization kettle 41 into liquid second evaporated liquid and return it to the first evaporation kettle 11 for recycling.

[0065] Example 2

[0066] This embodiment provides a separation and recovery method for a ZN type catalyst filtrate. The separation and recovery method is carried out in the separation and recovery system provided in Example 1. The ZN type catalyst filtrate comprises, by mass percentage, 42.67% toluene, 42.67% titanium tetrachloride, 0.55% tetrabutyl titanate, 0.84% ​​electron donor, 4.56% decane, 8.69% alcoholate titanium trichloride, and 0.02% catalyst fine powder.

[0067] (1) The ZN catalyst filtrate is passed into the first evaporation kettle 11 for first evaporation separation. The evaporation temperature is controlled at 130-150° C. and the evaporation is carried out until solid appears in the first evaporation kettle 11. The heating is stopped and the first evaporation kettle 11 is the residual liquid. The evaporated gas is the first evaporation liquid.

[0068] (2) The first evaporating liquid is introduced into a toluene distillation tower 21 for atmospheric distillation separation. The top of the tower is cooled and refluxed by circulating water, and the temperature is controlled at 105-120°C. The bottom of the tower is heated by steam, and the temperature is controlled at 110-135°C. Gaseous toluene is discharged from the top of the tower and condensed into liquid toluene for storage by a second condenser 22, and the first heavy component is discharged from the bottom of the tower.

[0069] (3) The first heavy component is discharged into a titanium tetrachloride distillation tower 31 for atmospheric distillation separation. The top of the tower is cooled and refluxed by circulating water, and the temperature is controlled at 130-150° C. The bottom of the tower is heated by steam, and the temperature is controlled at 135-155° C. The gaseous titanium tetrachloride is discharged from the top of the tower and condensed into liquid titanium tetrachloride for storage by a third condenser 32. The second heavy component is discharged from the bottom of the tower and returns to step (1) to continue to be introduced into the first evaporator 11 for recycling.

[0070] (4) The residual liquid is discharged into the alkalization kettle 41 for second evaporation separation, and the temperature of the alkalization kettle 41 is controlled to be 120-200°C until the liquid is evaporated to dryness. The evaporated steam is the second evaporated liquid, and the second evaporated liquid is passed into the first evaporation kettle 11 for recycling; a sodium hydroxide solution with a mass concentration of 20% is passed into the alkalization kettle 41 and mixed with the solid matter after the liquid is evaporated from the alkalization kettle 41 to perform an alkalization reaction to obtain an alkalized mixed liquid, which includes but is not limited to titanium dioxide, sodium chloride, water, decane, isooctyl alcohol, electron donor, catalyst fine powder, etc. The alkalization reaction is but is not limited to:

[0071] TICl4+NaOH→TiO2+NaCl+H2O

[0072] Ti(OC4H9)4+H2O→TiO2+C4H9OH

[0073] Ti(OC8H 17 )Cl3+H2O→TiO2+C8H 17 OH

[0074] (5) The alkalized mixed liquid is passed into a cyclone separator 42, and the alkalized mixed liquid is subjected to solid-liquid separation to obtain a solid by-product (mainly titanium dioxide) and an alkalized liquid. The alkalized liquid is passed into a water-oil separator for water-oil separation to obtain an aqueous phase liquid and an oily phase liquid. The aqueous phase liquid is sent to a water treatment system for centralized treatment; the oily phase liquid is passed into a decane / isooctanol distillation tower 45 for vacuum distillation, and the top of the tower is cooled and refluxed by circulating water. The temperature is controlled at 110 to 160° C. and the pressure is -0.08 to 0 MPa. Gaseous decane / isooctanol is extracted from the top of the tower, and the gaseous decane / isooctanol is condensed into liquid decane / isooctanol by a first condenser 46 and then passed into a drying tower 47 for drying and then collected and stored.

[0075] Example 3

[0076] The difference between this embodiment and embodiment 2 is that, by mass percentage, the ZN catalyst filtrate includes 0.5% toluene, 85.34% titanium tetrachloride, 0.55% tetrabutyl titanate, 0.84% ​​electron donor, 4.26% decane, 8.49% alcoholate titanium trichloride, and 0.02% catalyst fine powder.

[0077] Example 4

[0078] The difference between this embodiment and embodiment 2 is that, by mass percentage, the ZN catalyst filtrate includes 34.14% toluene, 51.20% titanium tetrachloride, 0.55% tetrabutyl titanate, 0.84% ​​electron donor, 4.56% decane, 8.69% alcoholate titanium trichloride, and 0.02% catalyst fine powder.

[0079] Test example

[0080] The purity of the toluene, titanium tetrachloride and decane / isooctanol products collected in Examples 2-4 above were respectively tested, and the results are shown in Table 1 below.

[0081] Table 1

[0082]

[0083]

[0084] From the above description, it can be seen that the above-mentioned embodiments of the present invention achieve the following technical effects: the separation and recovery method of the ZN-type catalyst filtrate provided in the present application sequentially performs a first evaporation separation, a first distillation separation, and a second distillation separation on the ZN-type catalyst filtrate, and sequentially performs a second evaporation separation and alkalization treatment on the residual liquid obtained by the first evaporation separation. This method not only recovers toluene and titanium tetrachloride, but also allows the first evaporated liquid and the second evaporated liquid to be further recycled and reused, effectively reducing energy waste and the recovery cost of the ZN-type catalyst filtrate, thereby improving economy and environmental protection, and has broad application prospects.

[0085] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for separating and recovering a ZN-type catalyst filtrate, characterized in that: The separation and recovery method comprises: Step S1, performing a first evaporation separation on the ZN catalyst filtrate to obtain a first evaporated liquid and a residual liquid; Step S2, performing a first distillation separation on the first evaporated liquid to obtain toluene and a first heavy component; Step S3, performing a second distillation separation on the first heavy component to obtain titanium tetrachloride and a second heavy component, and the second heavy component is returned to the step S1 and mixed with the ZN catalyst filtrate to continue the first evaporation separation; Step S4, sequentially subjecting the residual liquid to a second evaporation separation and alkalization treatment to obtain a second evaporated liquid and an alkalized product mixed liquid, and the second evaporated liquid is returned to step S1 to be mixed with the ZN-type catalyst filtrate to continue the first evaporation separation; The step S4 further comprises separating and recovering the alkalized mixed solution, which comprises: Step S41, performing solid-liquid separation on the alkalized mixed liquid to obtain a solid byproduct and an alkalized liquid; Step S42, separating the alkalized liquid into water and oil to obtain an aqueous phase liquid and an oil phase liquid; Step S43, performing a second evaporation separation on the oil phase to obtain a crude decane / isooctanol product and a first waste liquid; Step S44, subjecting the crude decane / isooctanol product to a third distillation separation to obtain decane / isooctanol and a second waste liquid; The ZN catalyst filtrate comprises, by mass percentage, 0.5-42.67% toluene, 42.67-85.34% titanium tetrachloride, 0.5-0.6% tetrabutyl titanate, 0.78-0.9% electron donor, 4.1-4.9% decane, 8.2-8.9% alcoholate titanium trichloride, and 0.02-0.05% catalyst fine powder; The temperature of the first evaporation separation is 130-150°C; the first distillation separation is atmospheric distillation separation, the temperature is 105-135°C; the second distillation separation is atmospheric distillation separation, the temperature is 130-155°C; the temperature of the second evaporation separation is 120-200°C; the third distillation separation is vacuum distillation, the temperature is 110-160°C, and the pressure is -0.08-0 MPa; The separation and recovery method is carried out in a separation and recovery system, which comprises: An evaporation separation unit, the evaporation separation unit comprising a first evaporation kettle (11), the first evaporation kettle (11) being used for evaporating and separating the ZN-type catalyst filtrate to obtain a first evaporated liquid and a residual liquid; A toluene separation unit, comprising a toluene distillation tower (21), the toluene distillation tower (21) being connected to the first evaporation kettle (11) and configured to distill and separate the first evaporating liquid to obtain toluene and a first heavy component; A titanium tetrachloride separation unit, comprising a titanium tetrachloride distillation tower (31), the titanium tetrachloride distillation tower (31) being connected to the toluene distillation tower (21) for distilling and separating the first heavy component to obtain titanium tetrachloride and a second heavy component; the titanium tetrachloride distillation tower (31) is also connected to the first evaporation kettle (11) for returning the second heavy component to the first evaporation kettle (11); a residual liquid treatment unit, the residual liquid treatment unit comprising an alkalization kettle (41), the alkalization kettle (41) being used to sequentially perform a second evaporation separation and alkalization treatment on the residual liquid to obtain a second evaporated liquid and an alkalized product mixed liquid, the alkalization kettle (41) being connected to the first evaporation kettle (11) and being used to return the second evaporated liquid to the first evaporation kettle (11); The residual liquid treatment unit further comprises a hydrocyclone (42), an oil-water separator (43), a second evaporation kettle (44) and a decane / isooctanol distillation tower (45) connected in sequence. The hydrocyclone (42) is connected to the alkalization kettle (41) and is used for separating the alkalized mixed liquid into solid and liquid to obtain a solid by-product and an alkalized liquid; the oil-water separator (43) is used for separating the alkalized liquid into water and oil to obtain an aqueous phase liquid and an oily phase liquid; the second evaporation kettle (44) is used for evaporating and separating the oily phase liquid to obtain a crude decane / isooctanol product and a first waste liquid; and the decane / isooctanol distillation tower (45) is used for distilling and separating the crude decane / isooctanol product to obtain decane / isooctanol and a second waste liquid.

2. The separation and recovery method according to claim 1, wherein The residual liquid treatment unit further comprises a drying tower (47), wherein the drying tower (47) is connected to the decane / isooctanol distillation tower (45), and the drying tower (47) is used to dry the decane / isooctanol; A first condenser (46) is further provided on the pipeline between the decane / isooctanol distillation tower (45) and the drying tower (47), and the first condenser (46) is used to condense the decane / isooctanol.

3. The separation and recovery method according to claim 1 or 2, characterized in that: The toluene separation unit further includes a second condenser (22), which is disposed on the top of the toluene distillation tower (21) and connected to the toluene distillation tower (21) for condensing the toluene; The titanium tetrachloride separation unit further includes a third condenser (32), which is disposed at the top of the titanium tetrachloride distillation tower (31) and is connected to the titanium tetrachloride distillation tower (31) for condensing the titanium tetrachloride; A fourth condenser (48) is further provided on the pipeline between the alkalization kettle (41) and the first evaporation kettle (11), and the fourth condenser (48) is used to condense the second evaporation liquid.

4. The separation and recovery method according to claim 1, wherein: The step S4 further includes: sequentially condensing and drying the decane / isooctanol.

5. The separation and recovery method according to claim 1, wherein: The step S2 further comprises condensing the toluene; The step S3 further includes condensation of the titanium tetrachloride; The step S4 further includes condensing the second evaporative liquid.

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