A method and system for treating a titanium tetrachloride liquor

Abstract

The application provides a titanium tetrachloride mother liquor treatment method and system. The method comprises the following steps: introducing the titanium tetrachloride mother liquor, TiO2 solid and HCl gas into a gas-solid-liquid three-phase reactor, and reacting TiO2 and HCl with TiCl4 and alkoxy titanium chloride in the mother liquor to generate titanium oxychloride; after separation, titanium oxychloride solid and gas-liquid phase materials are obtained; the titanium oxychloride solid is heated and decomposed to generate TiCl4 gas and TiO2 solid, and TiCl4 liquid is obtained after condensation of the TiCl4 gas. The system comprises a gas-solid-liquid three-phase reactor, a separation device, a thermal decomposition reactor and a condenser, etc. The method and system realize low-cost and efficient recovery of the titanium tetrachloride mother liquor.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of chemical industry, and particularly relates to a titanium tetrachloride mother liquor treatment method and system. BACKGROUND

[0002] Ziegler-Natta catalyst (Z-N catalyst) is one of the most important industrialized catalysts in the production of polyolefins at present. Among them, MgCl2 carrier type titanium Z-N catalyst has the widest application range. This catalyst contains carrier MgCl2, main catalyst TiCl4 and electron donor components. In the production process of this catalyst, excessive titanium tetrachloride and organic solvents are usually added, so catalyst mother liquor containing organic solvents, titanium tetrachloride and other materials is generated. In order to reduce the production cost of the catalyst, after the synthesis of the catalyst is completed, the solvent and titanium tetrachloride must be recovered from the mother liquor. The composition of the mother liquor is relatively complex, usually containing about 50-80% of titanium tetrachloride, 10-40% of alkane solvent, 1-10% of alkoxy titanium chloride, 0.1-5% of ester, and 0.1-2% of solid particles and other components. The commonly used mother liquor separation method is physical method, that is, using the boiling point difference between titanium tetrachloride and the solvent, adopting the way of thermal distillation to recover and utilize the organic solvent and titanium tetrachloride. This method is simple and easy to operate. However, due to the complex composition of the mother liquor, the tower kettle is easy to coke in the running process, the device running failure rate is high, the maintenance is frequent, the recovery efficiency of the solvent and titanium tetrachloride is low, and especially the purity index of titanium tetrachloride is difficult to meet the reuse standard, which directly affects the environmental protection compliance and economy of the catalyst production process.

[0003] In the prior art, CN103420413B discloses a method for recovering refined titanium tetrachloride from titanium-containing waste liquid. The method adds white oil as an azeotrope in the titanium-containing waste liquid, first separates the mixture of titanium tetrachloride and white oil in a distillation device, and then performs rectification on the mixture of titanium tetrachloride and white oil in a rectification device to obtain titanium tetrachloride. However, this method adds a new component, increases the recovery energy consumption, and the addition of the azeotrope affects the purity of the organic solvent. CN101717113A discloses a method for treating titanium tetrachloride mother liquor by combining low-temperature crystallization and atmospheric distillation. The method first cools the catalyst mother liquor at low temperature, and high-boiling substances are first crystallized and separated from the solution, and then atmospheric distillation is performed to separate high-purity titanium tetrachloride. However, this method needs to provide a large amount of cold energy, and the energy consumption is large, and the economy is poor. CN112704894A discloses a method for recovering titanium tetrachloride by combining multi-stage rectification and dry distillation. However, this method adopts a three-stage rectification and dry distillation scheme, the mother liquor treatment takes a long time, the operation is cumbersome, and the energy consumption is high.

[0004] Therefore, there is an urgent need for a low-cost and high-efficiency recovery technology for the mother liquor containing titanium tetrachloride in the preparation process of polyolefin catalyst. SUMMARY

[0005] To solve the above technical problems, the present application aims to provide a method and system for treating titanium tetrachloride mother liquor. The method and system can realize low-cost and high-efficiency recovery of titanium tetrachloride mother liquor.

[0006] To achieve the above-mentioned purpose, the present application provides a method for treating titanium tetrachloride mother liquor, which comprises the following steps:

[0007] (1) introducing the titanium tetrachloride mother liquor, TiO2 solid and HCl gas into a gas-solid-liquid three-phase reactor, and allowing the TiO2 and HCl to react with TiCl4 and alkoxy titanium chloride in the mother liquor to generate titanium oxychloride, and then separating the reaction product to obtain titanium oxychloride solid and gas-liquid phase materials;

[0008] (2) heating and decomposing the titanium oxychloride solid obtained in step (1) to generate TiCl4 gas and TiO2 solid, and then condensing the TiCl4 gas to obtain TiCl4 liquid.

[0009] In the above method, preferably, the titanium tetrachloride mother liquor comprises the following components in mass fraction: 50-80% of titanium tetrachloride, 10-40% of solvent, 1-10% of alkoxy titanium chloride, 1-20% of alcohol, 0.1-5% of ester and 0.1-2% of solid particles, etc. The solid particles mainly include catalyst small particles, etc.

[0010] According to the specific embodiment of the present application, preferably, the above method further comprises step (3): allowing the gas-liquid phase materials obtained in step (1) to be separated by gas-liquid separation to obtain gas materials and liquid materials. More preferably, the temperature of the gas-liquid separation is 20-40℃.

[0011] In the above method, preferably, in step (1), the TiO2 solid is nano-TiO2. More preferably, the TiO2 solid is anatase titanium dioxide with a grain size of 2-500 nm, and further preferably 2-10 nm.

[0012] In the above method, preferably, in step (1), the molar ratio of the amount of the TiO2 solid to the total amount of titanium tetrachloride and alkoxy titanium chloride in the titanium tetrachloride mother liquor is 3:1-1:1.

[0013] In the above method, preferably, in step (1), the molar ratio of the amount of the HCl gas to the total amount of titanium tetrachloride and alkoxy titanium chloride in the titanium tetrachloride mother liquor is 4:1-1:1.

[0014] In the above method, preferably, in step (1), the reaction temperature in the gas-solid-liquid three-phase reactor is 90-130℃, and the reaction pressure is 0.3-0.5 MPa. More preferably, the reaction temperature in the gas-solid-liquid three-phase reactor is 100-120℃, and the reaction pressure is 0.3-0.4 MPa.

[0015] In the above method, preferably, step (1) further comprises: cooling the post-reaction material in the gas-solid-liquid three-phase reactor to 60-80℃, and then separating the post-reaction material to obtain titanium oxychloride solids and gas-liquid phase material.

[0016] In the above method, preferably, in step (2), the temperature for heating and decomposing the titanium oxychloride solids obtained in step (1) is 280-350℃, more preferably 280-300℃.

[0017] In the above method, preferably, step (2) further comprises: returning the obtained TiO2 solids to the gas-solid-liquid three-phase reactor in step (1) to continue participating in the reaction.

[0018] In the above method, preferably, step (3) further comprises: returning the gas material to the gas-solid-liquid three-phase reactor in step (1) to continue participating in the reaction. The main components of the gas material are HCl and alkanes, etc. Returning the gas material to the gas-solid-liquid three-phase reactor effectively recycles the HCl gas.

[0019] In the above method, preferably, step (3) further comprises: passing the liquid material through a precision filter to remove a small amount of solid particles in the liquid material to obtain an organic liquid. The organic liquid can be introduced into a downstream rectification system for further rectification.

[0020] The second aspect of the present application provides a titanium tetrachloride mother liquor treatment system, which is used to implement the above-mentioned titanium tetrachloride mother liquor treatment method, and at least comprises: a gas-solid-liquid three-phase reactor, a separation device, a thermal decomposition reactor, and a condenser.

[0021] The gas-solid-liquid three-phase reactor is provided with at least a TiO2 solid feeding unit, an HCl gas feeding unit, a titanium tetrachloride mother liquor inlet, and a post-reaction material outlet.

[0022] The separation device is provided with at least an inlet, a solid material outlet, and a gas-liquid phase material outlet.

[0023] The thermal decomposition reactor is provided with at least an inlet, a solid material outlet, and a gas material outlet.

[0024] The outlet of the gas-solid-liquid three-phase reactor is connected with the inlet of the separation device, and the outlet of solid material of the separation device is connected with the inlet of the thermal decomposition reactor; the outlet of gaseous material of the thermal decomposition reactor is connected with the condenser.

[0025] According to the embodiment of the present application, preferably, the system further comprises a TiO2 solid return pipeline, one end of which is connected with the gas-solid-liquid three-phase reactor, and the other end of which is connected with the outlet of solid material of the thermal decomposition reactor, for returning the TiO2 solid generated after the heating decomposition of titanium oxychloride to the gas-solid-liquid three-phase reactor for further reaction.

[0026] According to the embodiment of the present application, preferably, the system further comprises a gas-liquid separation tank, which is provided with at least an inlet, an outlet of gaseous material and an outlet of liquid material; the inlet of the gas-liquid separation tank is connected with the outlet of gas-liquid phase material of the separation device, for separating the gas-liquid phase material into gaseous material and liquid material.

[0027] According to the embodiment of the present application, preferably, the system further comprises a gaseous material return pipeline, one end of which is connected with the gas-solid-liquid three-phase reactor, and the other end of which is connected with the outlet of gaseous material of the gas-liquid separation tank, for returning the gaseous material to the gas-solid-liquid three-phase reactor for recycling.

[0028] According to the embodiment of the present application, preferably, the system further comprises a precision filter, which is connected with the outlet of liquid material of the gas-liquid separation tank, for removing the small amount of solid particles in the liquid material to obtain organic liquid.

[0029] The present application provides a method and system for treating titanium tetrachloride mother liquor. The present application generates titanium oxychloride by using the chemical reaction of TiO2, HCl, TiCl4 and alkoxy titanium chloride in the mother liquor, and then decomposes the titanium oxychloride to generate gaseous TiCl4 and TiO2 solid, and the gaseous TiCl4 is condensed to obtain TiCl4 liquid. The present application uses a two-step chemical reaction method, i.e. using the synthesis and decomposition reaction of titanium oxychloride to separate TiCl4 from the mother liquor, which not only improves the recovery rate of TiCl4 in the mother liquor, but also greatly reduces the content of alkoxy titanium chloride in the mother liquor. The method and system of the present application realize low-cost and efficient recovery of titanium tetrachloride mother liquor, and are suitable for catalyst mother liquor recovery in the production process of polyolefin Ziegler-Natta catalyst. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 The schematic diagram of the structure of the titanium tetrachloride mother liquor treatment system provided for Example 1 and the flow of the treatment method provided for Example 2.

[0031] BRIEF DESCRIPTION OF DRAWINGS

[0032] 1-gas-solid-liquid three-phase reactor; 2-separation device; 3-thermal decomposition reactor; 4-condenser; 5-TiO2 solid return line; 6-gas-liquid separation tank; 7-gas material return line; 8-precision filter;

[0033] 101-TiO2 solid feeding unit; 102-HCl gas feeding unit; 103-titanium tetrachloride mother liquor inlet; 104-post-reaction material outlet. DETAILED DESCRIPTION

[0034] In order to have a clearer understanding of the technical features, objectives and beneficial effects of the present application, the technical solutions of the present application are described in detail as follows, but cannot be understood as limiting the scope of the present application.

[0035] In order to help understand the present application, some conditions and terms are defined as follows. The terms and conditions defined herein have the meanings commonly understood by those skilled in the art related to the present application.

[0036] Unless otherwise specified, the "titanium tetrachloride mother liquor" referred to herein refers to the combined liquid of the filtrate after filtration and the washing liquid of the washed catalyst after the synthesis step of the Z-N catalyst is completed, usually containing unreacted titanium tetrachloride, solvent, alkoxy titanium chloride, ester and solid particles, etc.

[0037] Unless otherwise specified, when the flow of the material stream as shown herein has a pressure change, there is a necessary pump or regulating valve, etc.

[0038] Unless otherwise specified, when the flow of the material stream as shown herein has a temperature change, there is a necessary heating and / or cooling device.

[0039] The specific embodiment of the present application provides a treatment method for titanium tetrachloride mother liquor, which comprises the following steps:

[0040] (1) The titanium tetrachloride mother liquor and TiO2 solid, HCl gas enter the gas-solid-liquid three-phase reactor, TiO2 and HCl react with TiCl4 and alkoxy titanium chloride in the mother liquor to generate titanium oxychloride, and after the reaction, the post-reaction material is separated to obtain titanium oxychloride solid and gas-liquid phase material;

[0041] (2) The titanium oxychloride solid obtained in step (1) is heated and decomposed to generate TiCl4 gas and TiO2 solid, and the TiCl4 gas is condensed to obtain TiCl4 liquid.

[0042] The titanium tetrachloride mother liquor treated in the present application can include the following components by mass fraction: 50-80% titanium tetrachloride, 10-40% solvent, 1-10% alkoxy titanium chloride, 1-20% alcohol, 0.1-5% ester, and 0.1-2% solid particles, etc. The solvent therein is generally an alkane. The solid particles therein mainly include catalyst small particles, etc.

[0043] In some specific embodiments, the above method further comprises step (3): subjecting the gas-liquid phase material obtained in step (1) to gas-liquid separation to obtain a gas material and a liquid material. Preferably, the temperature of the gas-liquid separation is 20-40°C.

[0044] In some specific embodiments, in step (1), the TiO2 solid is nano-TiO2. TiO2 exists in three crystalline forms: anatase, rutile, and brookite. The present application preferably uses anatase TiO2, and more preferably uses anatase TiO2 powder with a grain size of 2-10 nm.

[0045] In some specific embodiments, in step (1), the molar ratio of the amount of the TiO2 solid to the total amount of titanium tetrachloride and alkoxy titanium chloride in the titanium tetrachloride mother liquor is 3:1-1:1.

[0046] In some specific embodiments, in step (1), the molar ratio of the amount of the HCl gas to the total amount of titanium tetrachloride and alkoxy titanium chloride in the titanium tetrachloride mother liquor is 4:1-1:1.

[0047] In some specific embodiments, in step (1), the reaction temperature in the gas-solid-liquid three-phase reactor is 90-130°C, and the reaction pressure is 0.3-0.5 MPa. More preferably, the reaction temperature in the gas-solid-liquid three-phase reactor is 100-120°C, and the reaction pressure is 0.3-0.4 MPa.

[0048] In some specific embodiments, step (1) further comprises: after the reaction in the gas-solid-liquid three-phase reactor, the post-reaction material is cooled to 60-80°C, and then subjected to separation to obtain a titanium oxychloride solid and a gas-liquid phase material.

[0049] In some specific embodiments, in step (2), the temperature for heating and decomposing the titanium oxychloride solid obtained in step (1) is 280-350°C, and more preferably 280-300°C.

[0050] In some specific embodiments, step (2) further comprises: returning the obtained TiO2 solid to the gas-solid-liquid three-phase reactor in step (1) to continue participating in the reaction.

[0051] In some embodiments, step (3) further comprises: returning the gaseous material to the gas-solid-liquid three-phase reactor in step (1) to continue participating in the reaction. The main components of the gaseous material are HCl and alkanes, etc. Returning the gaseous material to the gas-solid-liquid three-phase reactor effectively recycles the HCl gas.

[0052] In some embodiments, step (3) further comprises: removing a small amount of solid particles in the liquid material through a precision filter to obtain an organic liquid. After removing a small amount of solid particles (i.e. catalyst small particles, etc.), the main components of the organic liquid are alkanes and esters, etc. The organic liquid can enter a downstream rectification system for further rectification.

[0053] The embodiments of the present application also provide a titanium tetrachloride mother liquor treatment system, which is used to implement the above-mentioned titanium tetrachloride mother liquor treatment method, and at least comprises: a gas-solid-liquid three-phase reactor, a separation device, a thermal decomposition reactor and a condenser.

[0054] The gas-solid-liquid three-phase reactor is provided with at least a TiO2 solid feeding unit, an HCl gas feeding unit, a titanium tetrachloride mother liquor inlet and a post-reaction material outlet.

[0055] The separation device is provided with at least an inlet, a solid material outlet and a gaseous-liquid phase material outlet.

[0056] The thermal decomposition reactor is provided with at least an inlet, a solid material outlet and a gaseous material outlet.

[0057] The post-reaction material outlet of the gas-solid-liquid three-phase reactor is in communication with the inlet of the separation device, the solid material outlet of the separation device is in communication with the inlet of the thermal decomposition reactor, and the gaseous material outlet of the thermal decomposition reactor is in communication with the condenser.

[0058] In some embodiments, the gas-solid-liquid three-phase reactor can adopt a form conventional in the art, such as a trickle bed, a stirred tank, a slurry bed, a fluidized bed and a carried bed, etc.

[0059] In some embodiments, the separation device can adopt a filter device conventional in the art, such as a vacuum drum filter and a plate-and-frame filter, etc.

[0060] In some embodiments, the thermal decomposition reactor can adopt a reactor conventional in the art, as long as it can realize the function of pyrolyzing titanium oxychloride solid, such as a high-temperature reaction kettle, etc.

[0061] In some embodiments, the system further comprises a TiO2 solid return pipeline, one end of which is in communication with the gas-solid-liquid three-phase reactor, and the other end of which is in communication with a solid material outlet of the thermal decomposition reactor, for returning the TiO2 solid generated after the thermal decomposition of the titanium oxychloride to the gas-solid-liquid three-phase reactor for further reaction.

[0062] In some embodiments, the system further comprises a gas-liquid separation tank, which is provided with at least an inlet, a gas material outlet and a liquid material outlet; the inlet of the gas-liquid separation tank is in communication with the gas-liquid phase material outlet of the separation device, for separating the gas-liquid phase material into gas material and liquid material.

[0063] In some embodiments, the system further comprises a gas material return pipeline, one end of which is in communication with the gas-solid-liquid three-phase reactor, and the other end of which is in communication with the gas material outlet of the gas-liquid separation tank, for returning the gas material to the gas-solid-liquid three-phase reactor for recycling.

[0064] In some embodiments, the system further comprises a precision filter, which is in communication with the liquid material outlet of the gas-liquid separation tank, for removing a small amount of solid particles in the liquid material to obtain an organic liquid.

[0065] In the system for treating the titanium tetrachloride mother liquor, the gas-solid-liquid three-phase reactor is provided, and titanium oxychloride is generated by the chemical reaction of TiO2, HCl and TiCl4 and alkoxy titanium chloride in the mother liquor. On one hand, TiO2 reacts with TiCl4 in the mother liquor to generate titanium oxychloride (the reaction process mainly includes: TiCl4+TiO2=2TiOCl2, TiCl4+3TiO2=2Ti2O3Cl2), which converts the liquid phase titanium tetrachloride in the mother liquor into solid phase titanium oxychloride, thereby realizing the separation of TiCl4 and the mother liquor. On the other hand, TiO2, HCl and alkoxy titanium chloride in the mother liquor react to generate titanium oxychloride and alcohol (the main reaction equations are as follows: TiCl(OR)3+HCl→TiCl2(OR)2·ROH……(1), TiCl2(OR)2·ROH+HCl→TiCl3(OR)·2ROH……(2), TiCl3(OR)·2ROH+HCl→TiCl4+3ROH……(3), TiCl4+TiO2=2TiOCl2……(4), TiCl4+3TiO2=2Ti2O3Cl2……(5)), which greatly reduces the content of alkoxy titanium chloride in the mother liquor and improves the recovery rate of the initial raw material TiCl4.

[0066] In addition, the titanium oxychloride is heated and decomposed to generate gaseous TiCl4 and solid TiO2 (the reaction process mainly includes: TiO x Cly →TiCl4+TiO2), this process is carried out in a thermal decomposition reactor, and then the gaseous TiCl4 is condensed to generate high-purity TiCl4 liquid with a purity of over 99.9%. The generated solid TiO2 is returned to the gas-solid-liquid three-phase reactor for reuse.

[0067] In addition, the present invention performs gas-liquid separation on the gas-liquid phase materials generated in the gas-solid-liquid three-phase reactor, and then returns the gaseous materials to the gas-solid-liquid three-phase reactor, thus effectively recovering and utilizing HCl gas.

[0068] In addition, the present invention filters the liquid material obtained after gas-liquid separation of gas-liquid phase materials through a precision filter to remove a small amount of solid particles, resulting in an organic liquid that can enter the downstream distillation system. This makes the raw material composition in the distillation system simpler and cleaner, ensuring the efficient and stable operation of the distillation system.

[0069] The technical solutions of the present invention are specifically illustrated below through embodiments, but the present invention is not limited to these embodiments. Of course, various modifications can be made within the scope of the key points of the present invention.

[0070] Example 1

[0071] This embodiment provides a treatment system for titanium tetrachloride mother liquor, the structure of which is as follows: Figure 1 As shown, the system includes: a gas-solid-liquid three-phase reactor 1, a separation device 2, a thermal decomposition reactor 3, a condenser 4, a TiO2 solid return pipeline 5, a gas-liquid separation tank 6, a gas material return pipeline 7, and a precision filter 8;

[0072] The gas-solid-liquid three-phase reactor 1 is equipped with at least a TiO2 solid feeding unit 101, an HCl gas feeding unit 102, a titanium tetrachloride mother liquor inlet 103, and a reaction material outlet 104.

[0073] The separation device 2 is provided with at least an inlet, a solid material outlet, and a gas-liquid phase material outlet;

[0074] The pyrolysis reactor 3 is equipped with at least an inlet, a solid material outlet, and a gaseous material outlet;

[0075] The gas-liquid separator 6 is equipped with at least an inlet, a gaseous material outlet, and a liquid material outlet;

[0076] The material outlet 104 of the gas-solid-liquid three-phase reactor 1 is connected to the inlet of the separation device 2, the solid material outlet of the separation device 2 is connected to the inlet of the thermal decomposition reactor 3, and the gas material outlet of the thermal decomposition reactor 3 is connected to the condenser 4.

[0077] One end of the TiO2 solid return pipeline 5 is communicated with the gas-solid-liquid three-phase reactor 1, and the other end is communicated with the solid material outlet of the thermal decomposition reactor 3, for returning the TiO2 solid generated after the heating decomposition of the titanium oxychloride solid to the gas-solid-liquid three-phase reactor 1 to continue participating in the reaction;

[0078] The inlet of the gas-liquid separation tank 6 is communicated with the gas-liquid phase material outlet of the separation device 2, for carrying out gas-liquid separation on the gas-liquid phase material to obtain gas material and liquid material;

[0079] One end of the gas material return pipeline 7 is communicated with the gas-solid-liquid three-phase reactor 1, and the other end is communicated with the gas material outlet of the gas-liquid separation tank 6, for returning the gas material to the gas-solid-liquid three-phase reactor 1 for recycling;

[0080] The precision filter 8 is communicated with the liquid material outlet of the gas-liquid separation tank 6, for removing a small amount of solid particles in the liquid material to obtain organic liquid.

[0081] Wherein, the gas-solid-liquid three-phase reactor 1 can adopt a form conventional in the art, such as a trickle bed, a stirred tank, a slurry bed, a fluidized bed and a carried bed, etc.

[0082] The separation device 2 can adopt a filter device conventional in the art, such as a vacuum drum filter, a plate-frame filter, etc.

[0083] The thermal decomposition reactor 3 can adopt a reactor conventional in the art, as long as it can realize the pyrolysis function of the titanium oxychloride solid, such as a high-temperature reaction kettle, etc.

[0084] In addition, it needs to be explained that, in order to simplify the description of the present application and facilitate understanding, Figure 1 The material storage equipment, material conveying equipment, heating and cooling equipment, pipe valves, electrical instruments and other conventional devices familiar to those skilled in the art of chemical industry are not shown in the figure, but the system of the present application can include these devices.

[0085] Example 2

[0086] The present embodiment provides a treatment method of titanium tetrachloride mother liquor, the flow chart of which is shown in Figure 1 The method adopts the treatment system of titanium tetrachloride mother liquor provided in Example 1.

[0087] The titanium tetrachloride mother liquor treated in the embodiment includes the following components in mass fraction: 67.8% of titanium tetrachloride, 20.2% of n-hexane, 5.3% of decane, 3.0% of butanol, 3.1% of n-butoxy titanium trichloride (TiCl3(OC4H9)), 0.2% of diisobutyl phthalate (DIBP), 0.1% of tetraethyl orthosilicate (TEOS), and 0.3% of solid particles such as catalyst small particles. The titanium tetrachloride mother liquor is from a polyolefin catalyst synthesis section.

[0088] The method of the embodiment includes the following steps:

[0089] (1) The titanium tetrachloride mother liquor, TiO2 solid, and HCl gas enter a gas-solid-liquid three-phase reactor 1. TiO2 and HCl react with TiCl4 and alkoxy titanium chloride in the mother liquor to generate titanium oxychloride. The reaction temperature is 100-120°C, and the reaction pressure is 0.3-0.4 MPa. The generated titanium oxychloride is a yellow precipitate. The post-reaction material is obtained. After the post-reaction material is cooled to 60-80°C, it is separated by a separation device 2 to obtain titanium oxychloride solid and gas-liquid phase material;

[0090] (2) The titanium oxychloride solid obtained in step (1) enters a thermal decomposition reactor 3 for heating and decomposition. The heating and decomposition temperature is 280-300°C. TiCl4 gas and TiO2 solid are generated. The TiCl4 gas is cooled to room temperature by a condenser 4 to obtain TiCl4 liquid. The purity of the TiCl4 liquid is above 99.9%, which can be recycled to a polyolefin catalyst synthesis section for direct use in the synthesis of Z-N catalyst. The obtained TiO2 solid is crushed and returned to the gas-solid-liquid three-phase reactor 1 in step (1) for further reaction;

[0091] (3) The gas-liquid phase material obtained in step (1) is cooled to 20-40°C by a gas-liquid separation tank 6 for gas-liquid separation to obtain gas material and liquid material. The gas material is returned to the gas-solid-liquid three-phase reactor 1 in step (1) for further reaction. The main components of the gas material are HCl and alkanes, etc., which are effectively recycled to the gas-solid-liquid three-phase reactor 1 for HCl gas recovery. The liquid material passes through a precision filter 8 to remove a small amount of fine solid particles to obtain an organic liquid. The organic liquid can enter a downstream rectification system for further rectification.

[0092] In the embodiment, the TiO2 solid used in step (1) is anatase titanium dioxide powder with a crystal grain size of 2-10 nm. The molar ratio of the amount of TiO2 solid used in step (1) to the total amount of titanium tetrachloride and alkoxy titanium chloride in the titanium tetrachloride mother liquor is 2:1. The molar ratio of the amount of HCl gas used in step (1) to the total amount of titanium tetrachloride and alkoxy titanium chloride in the titanium tetrachloride mother liquor is 1:1.

[0093] In the present embodiment, the organic liquid in step (3) comprises the following mass fractions of components: 63.3% of n-hexane, 16.7% of decane, 19.1% of butanol, 0.6% of diisobutyl phthalate (DIBP), and 0.3% of tetraethyl orthosilicate (TEOS).

[0094] The concentration of titanium in the titanium tetrachloride mother liquor and the concentration of titanium in the organic liquid obtained in step (3) are determined by spectrophotometry, and the recovery rate of titanium is calculated. The specific method comprises:

[0095] The optical density of the solution after recovery (i.e., the organic liquid) and the solution before recovery (i.e., the titanium tetrachloride mother liquor) is determined using H2O2 as an indicator, and then the concentration of Ti in the solution is calculated using the formula E = K x C x L, and the recovery rate of titanium is calculated; in the formula: E is the optical density;

[0096] K is the extinction coefficient, which is measured using a standard Ti solution;

[0097] C is the concentration of Ti in the solution, mg / mL;

[0098] L is the colorimetric thickness, cm.

[0099] The recovery rate of titanium tetrachloride in the present embodiment is 99.6%.

[0100] As can be seen from the above embodiments, the technical scheme of the present application is used for the recovery of titanium tetrachloride mother liquor in the production process of Ziegler-Natta catalyst, and through the two-step chemical reaction mode, TiCl4 in the mother liquor can be effectively separated out, and the content of alkoxy titanium chloride in the mother liquor is greatly reduced, thereby realizing efficient and low-cost recovery of the TiCl4 mother liquor. In addition, the present application returns the TiO2 solid generated by heating and decomposing titanium oxychloride back to the gas-solid-liquid three-phase reactor for repeated use, and returns the gas material obtained after gas-liquid separation of the gas-liquid phase material generated in the gas-solid-liquid three-phase reactor to the gas-solid-liquid three-phase reactor, thereby effectively recovering and utilizing the HCl gas, thus realizing full recovery and utilization of resources. In addition, after filtration by the precision filter, the remaining components in the mother liquor are simpler, so that when going to the downstream rectification system, the raw material components in the rectification system are simpler and cleaner, thereby ensuring efficient and long-term stable operation of the rectification system.

[0101] Obviously, the above embodiments of the present application are merely exemplary for clearly illustrating the present application, and are not intended to limit the implementation manners of the present application. Based on the above description, other different forms of changes or variations can be made by those skilled in the art, and here, all the implementation manners cannot be exhausted, and any obvious changes or variations derived from the technical solutions of the present application are still within the protection scope of the present application.

Claims

1. A method for treating a titanium tetrachloride mother liquor, comprising the following steps: (1) introducing the titanium tetrachloride mother liquor, TiO2 solid and HCl gas into a gas-solid-liquid three-phase reactor, and allowing the TiO2, HCl and TiCl4 and titanium alkoxy chloride in the mother liquor to react to form titanium oxychloride, and then separating the reaction product to obtain titanium oxychloride solid and gas-liquid phase materials; (2) heating and decomposing the titanium oxychloride solid obtained in step (1) to form TiCl4 gas and TiO2 solid, and then condensing the TiCl4 gas to obtain TiCl4 liquid.

2. The method of claim 1, wherein, The titanium tetrachloride mother liquor comprises the following components by mass fraction: 50-80% titanium tetrachloride, 10-40% solvent, 1-10% titanium alkoxy chloride, 1-20% alcohol, 0.1-5% ester and 0.1-2% solid particles.

3. The method of claim 1, wherein, The method further comprises step (3): allowing the gas-liquid phase materials obtained in step (1) to be separated by gas-liquid separation to obtain gas materials and liquid materials.

4. The method of claim 3, wherein, The temperature for the gas-liquid separation is 20-40°C.

5. The method of claim 1, wherein, In step (1), the TiO2 solid is nano TiO2.

6. The method of claim 1 or 5, wherein, In step (1), the TiO2 solid is anatase titanium dioxide with a grain size of 2-500 nm.

7. The method of claim 1 or 2, wherein, In step (1), the molar ratio of the amount of the TiO2 solid to the total amount of titanium tetrachloride and titanium alkoxy chloride in the titanium tetrachloride mother liquor is 3:1-1:

1.

8. The method of claim 1 or 2, wherein, In step (1), the molar ratio of the amount of the HCl gas to the total amount of titanium tetrachloride and titanium alkoxy chloride in the titanium tetrachloride mother liquor is 4:1-1:

1.

9. The method of claim 1, wherein, In step (1), the reaction temperature in the gas-solid-liquid three-phase reactor is 90-130°C, and the reaction pressure is 0.3-0.5 MPa.

10. The method of claim 9, wherein, In step (1), the reaction temperature in the gas-solid-liquid three-phase reactor is 100-120°C, and the reaction pressure is 0.3-0.4 MPa.

11. The method of claim 1, wherein, Step (1) further comprises: allowing the reaction product in the gas-solid-liquid three-phase reactor to be cooled to 60-80°C, and then separating the product to obtain titanium oxychloride solid and gas-liquid phase materials.

12. The method of claim 1, wherein, In step (2), the temperature for heating and decomposing the titanium oxychloride solid obtained in step (1) is 280-350°C.

13. The method of claim 1, wherein, Step (2) further comprises: allowing the obtained TiO2 solid to return to the gas-solid-liquid three-phase reactor in step (1) to continue participating in the reaction.

14. The method of claim 3, wherein, Step (3) further comprises: allowing the gas materials to return to the gas-solid-liquid three-phase reactor in step (1) to continue participating in the reaction.

15. The method of claim 3, wherein, Step (3) further comprises: allowing the liquid materials to pass through a precision filter to remove a small amount of solid particles therefrom to obtain organic liquid.

16. A system for treating a titanium tetrachloride mother liquor, the system being for implementing the method for treating a titanium tetrachloride mother liquor according to any one of claims 1 to 15, the system comprising at least: A gas-solid-liquid three-phase reactor, a separation device, a thermal decomposition reactor and a condenser; The gas-solid-liquid three-phase reactor is provided with at least a TiO2 solid feeding unit, an HCl gas feeding unit, a titanium tetrachloride mother liquor inlet and a reaction product outlet; The separation device is provided with at least an inlet, a solid material outlet and a gas-liquid phase material outlet; The thermal decomposition reactor is provided with at least an inlet, a solid material outlet and a gas material outlet; and The condenser is provided with at least an inlet and a liquid outlet. The gas-solid-liquid three-phase reactor is connected with the inlet of the separation device, and the solid material outlet of the separation device is connected with the inlet of the thermal decomposition reactor; the gas material outlet of the thermal decomposition reactor is connected with the condenser.

17. The system of claim 16, wherein, The system further comprises a TiO2 solid return pipeline, one end of which is connected with the gas-solid-liquid three-phase reactor, and the other end of which is connected with the solid material outlet of the thermal decomposition reactor, for returning the TiO2 solid generated after the heating decomposition of the titanium oxychloride solid to the gas-solid-liquid three-phase reactor to continue participating in the reaction.

18. The system of claim 16, wherein, The system further comprises a gas-liquid separation tank, which is provided with at least an inlet, a gas material outlet and a liquid material outlet; the inlet of the gas-liquid separation tank is connected with the gas-liquid phase material outlet of the separation device, for carrying out gas-liquid separation on the gas-liquid phase material to obtain gas material and liquid material.

19. The system of claim 18, wherein, The system further comprises a gas material return pipeline, one end of which is connected with the gas-solid-liquid three-phase reactor, and the other end of which is connected with the gas material outlet of the gas-liquid separation tank, for returning the gas material to the gas-solid-liquid three-phase reactor for recycling.

20. The system of claim 18, wherein, The system further comprises a precision filter, which is connected with the liquid material outlet of the gas-liquid separation tank, for removing a small amount of solid particles in the liquid material to obtain organic liquid.

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