Supercritical hydrothermal and solvothermal synthesis of nanocomposite zirconia system and quality control method

Abstract

The application discloses a supercritical hydrothermal and solvothermal synthesis nanometer composite zirconia system and quality control method, belongs to the technical field of energy chemical industry, and sets material composite deployment and delivery unit, heat reuse unit, reaction post-processing unit and additional product recovery unit to constitute the whole preparation system. The supercritical hydrothermal and solvothermal synthesis nanometer composite zirconia system integrates energy reuse, additional product recovery and quality control and the like into one, can realize heat energy efficient utilization, additional product recovery and quality efficient control system, can realize energy level matching in the heat energy utilization process, can realize resource utilization in the post-processing link, can realize nanometer zirconia particle size control, purity control, crystal form stability and anti-agglomeration in the whole system operation, improves system thermal efficiency, reduces operation cost, saves energy, and simultaneously obtains high-quality nanometer zirconia particles, and lays a foundation for the industrialization process of continuous supercritical hydrothermal / solvothermal synthesis.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of energy chemical industry, and particularly relates to a system for synthesizing nano-composite zirconia by supercritical hydrothermal and solvothermal methods and a quality control method. BACKGROUND

[0002] Nanoceramics have developed rapidly in the past few decades and have broad application prospects. Nano-zirconia powder is widely used as a raw material for thermal barrier coatings, denture materials, mobile phone back plates, gas sensors, supercapacitors, fuel cell electrolytes, catalysts and catalytic carriers, etc. due to its excellent toughness, strength, corrosion resistance and biocompatibility, etc. physical and chemical properties. Under ambient pressure, cubic phase, tetragonal phase and monoclinic phase are three forms of ZrO2 crystal structure, which can be prepared at room temperature~1170℃, 1170~2370℃ and 2370~2706℃, respectively. When the temperature is higher than 2706℃, zirconia will become a molten state. By taking certain measures, such as doping and changing reaction conditions, the cubic phase and tetragonal phase of ZrO2 crystals can be partially or completely stable at room temperature.

[0003] At present, the methods for synthesizing nano-zirconia include sol-gel method, chemical co-precipitation method, spray pyrolysis method, etc. Although micron and nano zirconia can be formed, these methods have many shortcomings, including slow reaction speed, complex and time-consuming process, high energy consumption (need to calcine to remove some impurities), etc. Therefore, there is an urgent need for a simple process, fast reaction speed and low cost preparation method. The continuous supercritical hydrothermal and solvothermal synthesis method can directly obtain crystalline materials from aqueous solution by cleverly controlling parameters. With the increase of temperature, metal oxides such as zirconia are rapidly precipitated due to their low solubility at high temperature, which has the advantages of high efficiency, low cost, controllable reaction, environmental protection, etc.

[0004] The reaction system involved in the process flow of continuous supercritical hydrothermal synthesis and solvothermal synthesis mainly includes a material conveying unit, a temperature and pressure increasing unit, a mixing / reaction unit, a temperature and pressure decreasing unit and a post-processing unit. However, in the process of synthesizing nano zirconia, there are still many problems in these units: for example, the patent document CN200880127076.3 discloses a continuous hydrothermal reactor system which can be used in a method for preparing, for example, the nano particles containing zirconia, which is limited to the production of zirconia nanoparticles, and in the material conveying unit, there is only a mixed liquid path without considering the problems of zirconia particle size control, crystal form stability and anti-aggregation; in the design of the whole system, the purity control problem is not considered, and the material is mostly selected from stainless steel 304 or 316, which has great corrosion risk. For example, the patent document CN201210122862.2 discloses a method for preparing a manganese-based solid solution positive electrode material by a supercritical solvothermal method, in the temperature and pressure increasing unit and the post-processing link, the heat of the high-temperature fluid is directly dissipated, which causes a large amount of waste of energy and increases the operation cost of the system. For example, the patent document CN201710232863.5 discloses a method for continuously synthesizing lithium iron phosphate by a supercritical solvothermal method, although it is not for preparing zirconia, but for the continuous supercritical solvothermal synthesis technology, the post-processing link after the continuous reaction is completely not considered in the system, and the wastewater is directly discharged after the continuous reaction, without considering the resource utilization and additional product recovery. SUMMARY

[0005] In order to overcome the above-mentioned defects of the prior art, the purpose of the present application is to provide a supercritical hydrothermal and solvothermal synthesis nano composite zirconia system and quality control method, so as to solve the technical problems that the prior art cannot reasonably utilize heat, there is no resource utilization of additional products, and the purity and crystal form of the produced nano zirconia product cannot be effectively controlled.

[0006] In order to achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0007] The present application discloses a supercritical hydrothermal and solvothermal synthesis nano composite zirconia system, which comprises a material composite preparation and conveying unit, a heat recycling unit, a reaction post-processing unit and an additional product recovery unit; wherein:

[0008] The material composite preparation and conveying unit comprises a composite storage tank one for adding a ligand, a composite storage tank two for adding a stabilizer, a precursor storage tank, a solvent storage tank and an additive storage tank, the outlet end pipelines of the composite storage tank one and the composite storage tank two are connected with the inlet end of the precursor storage tank through a low-pressure pump after being converged, and a high-pressure pump one, a high-pressure pump two and a high-pressure pump three are respectively arranged on the outlet pipelines of the precursor storage tank, the solvent storage tank and the additive storage tank, which are all used for conveying materials;

[0009] The heat recycling unit comprises, in sequence, a heater, a mixing unit, a reaction unit, a cooling unit, and a slow cooling unit. The outlets of the high-pressure pump one, the heater, and the high-pressure pump three are connected to the mixing unit through pipelines. The outlet of the cooling unit is divided into two paths, one of which is connected to the first inlet of the heater, and the other of which is connected to the hot side inlet of the slow cooling unit. The outlet of the high-pressure pump two is divided into two paths, one of which is connected to the second inlet of the heater through a valve one, and the other of which is connected to the cooling unit through a valve two.

[0010] The outlet of the slow cooling unit is divided into two paths, one of which is connected to the reaction post-processing unit, and the other of which is connected to the additional product recycling unit.

[0011] The reaction post-processing unit is used to process the zirconium oxide nano product obtained by the reaction.

[0012] The additional product recycling unit is used to recycle the additional product of the reaction.

[0013] Preferably, the reaction post-processing unit comprises a pressure reduction unit, a gas-liquid separation unit, a waste gas treatment unit, a solid-liquid separation unit, a drying unit, and a nano product storage unit. The cold side outlet of the slow cooling unit is connected to the inlet of the pressure reduction unit. The outlet of the pressure reduction unit is connected to the inlet of the gas-liquid separation unit. The outlet of the gas-liquid separation unit is divided into two paths, one of which is connected to the waste gas treatment unit, and the other of which is connected to the inlet of the solid-liquid separation unit. The outlet of the solid-liquid separation unit is divided into two paths, one of which is connected to the drying unit, and the other of which is connected to the additional product recycling unit. The outlet of the drying unit is connected to the nano product storage unit.

[0014] Further preferably, the additional product recycling unit comprises, in sequence, a membrane treatment unit, a falling film evaporation unit, and an additional product storage unit. The inlet of the membrane treatment unit is connected to one of the outlets of the solid-liquid separation unit. The hot side outlet of the slow cooling unit is connected to one inlet of the falling film evaporation unit. One outlet of the falling film evaporation unit is connected to the slow cooling unit through a pipeline.

[0015] Preferably, a plurality of complexing agent storage tanks are arranged on the pipeline before the low-pressure pump, for separately packaging ligands and / or stabilizers. The outlets of all the complexing agent storage tanks are connected to the precursor storage tank through the low-pressure pump.

[0016] Preferably, the heater is not limited to the forms of electromagnetic heater, infrared heater, or resistance heater, etc. The mixing unit is not limited to the forms of T-shaped three-way mixer, jacketed countercurrent mixer, and cross-shaped jet mixer, etc.

[0017] Preferably, the reaction unit adopts a tubular reactor or a kettle-type reactor, which is arranged as one reactor, or is composed of a plurality of reactors in series or in parallel. The heat exchange forms of the cooling unit and the slow cooling unit are not limited to the forms of coil or jacket. The membrane treatment unit is not limited to the forms of forward osmosis, RO reverse osmosis, or ultrafiltration membrane, etc.

[0018] Preferably, the material of the pipeline and reaction element of the system is not limited to nickel-based alloy, titanium-lined stainless steel or non-metallic coating, etc.

[0019] The application also discloses a method for quality control of nano-composite zirconia based on the supercritical hydrothermal and solvothermal synthesis of nano-composite zirconia, which comprises the following steps:

[0020] The ligand is stored in the composite storage tank one, the stabilizer is stored in the composite storage tank two, the precursor storage tank is pumped into for mixing and storage through the low-pressure pump, the material after pressure boosting by the high-pressure pump one reaches the critical pressure value of the supercritical hydrothermal synthesis, the material after pressure boosting is punched into the mixing unit, the alkali solution in the additive storage tank is pumped into the mixing unit after pressure boosting by the high-pressure pump three;

[0021] Valve one is opened, the solvent in the solvent storage tank is pumped into the heater after pressure boosting by the high-pressure pump two, the solvent is heated to the supercritical temperature and then is introduced into the mixing unit, the solvent is fully mixed with the alkali solution and the precursor mixture in the mixing unit, and then is introduced into the reaction unit to generate hydrolysis and dehydration reactions, and then is gradually cooled through the cooling unit and the slow cooling unit;

[0022] Valve one is closed, and valve two is opened, the unheated solvent is introduced into the cooling unit to fully exchange heat with the hot fluid after the reaction in step 2), is preheated and then is introduced into the heater to be heated to the supercritical state, the heat exchange cycle is realized, the temperature of the hot fluid is reduced from 400 DEG C to 200-300 DEG C after cooling, the medium-temperature fluid after heat exchange and cooling is introduced into the slow cooling unit, the steam generated by the waste heat is used for the additional product recovery unit, and the additional product recovery unit is further cooled to enter the reaction post-processing unit.

[0023] Preferably, the solid-liquid-gas three-phase mixture entering the reaction post-processing unit is divided into two routes in the gas-liquid separation unit, the gas phase is introduced into the waste gas treatment unit, the waste gas is used for gas heating to supply the heater, the solid-liquid phase is introduced into the solid-liquid separation unit, the solid phase is introduced into the drying unit to be dried, the obtained nano-composite zirconia powder is stored in the nano product storage unit, the liquid phase is introduced into the membrane treatment unit, the solvent is filtered out, the high-purity additional product is obtained through the falling film evaporation unit, and the high-purity additional product is stored in the additional product storage unit.

[0024] Preferably, the method comprises the following steps:

[0025] The proportion of the ligand and the stabilizer in the composite storage tank one and the composite storage tank two and the zirconium precursor is changed, the particle anti-agglomeration and the product crystal form are controlled;

[0026] The proportion of the alkali solution and the zirconium precursor in the additive storage tank is changed to adjust the pH value, the electric heating power and the pressure setting value are controlled to change the reaction temperature and the pressure, the number and the connection form of the reactors of the reaction unit are changed to change the reaction time, and the particle size of the nano zirconia particles is controlled.

[0027] The whole system pipeline and element adopt nickel base alloy or stainless steel titanium lining material to prevent system corrosion and impurity, and control the purity of nano zirconia particles.

[0028] Compared with the prior art, the application has the following beneficial effects:

[0029] The supercritical hydrothermal and solvothermal synthesis nano composite zirconia system disclosed by the application comprises a material composite preparation and conveying unit, a heat recycling unit, a post-reaction treatment unit and an additional product recovery unit, and has three advantages:

[0030] First, the material composite preparation and conveying unit is provided with a composite tank one for adding a ligand and a composite tank two for adding a stabilizer, the ligand and the stabilizer are mixed and then input into a precursor tank body, and the precursor, the solvent and the additive are conveyed through three paths to a mixing unit by a solvent tank and an additive tank, so that the particle size of the nano zirconia particles can be controlled by changing the type of the precursor, the reaction time and the pH value, and the stabilizer and the organic ligand can be added through a composite agent conveying pipeline to realize the stabilization of tetragonal phase and cubic phase and the anti-agglomeration of particles, thereby realizing the quality control of the nano zirconia.

[0031] Second, in the heat recycling unit, the high-temperature and high-pressure fluid flowing out of the reaction unit is subjected to multi-stage heat exchange through a cooling unit and a slow cooling unit in the heat recycling unit, the cold fluid is preheated, and steam is provided for a falling film unit for product recovery, so that the heat is utilized in stages and the operation cost of the system is reduced.

[0032] Third, the system is provided with a post-treatment unit and an additional product recovery unit, which can well treat the nano zirconia product obtained by the reaction and effectively recover the high-value by-products through the additional product recovery unit, so that the system resources are reasonably utilized.

[0033] Therefore, it can be seen that the supercritical hydrothermal and solvothermal synthesis nano composite zirconia system integrates quality control, energy recycling and additional product recovery, can realize efficient utilization of heat energy, recovery of additional products and efficient quality control, can realize energy level matching in the process of heat energy utilization, can realize resource utilization in the post-treatment link, can realize particle size control, purity control, crystal type stabilization and anti-agglomeration of the nano zirconia in the whole system operation, improves the system thermal efficiency, reduces the operation cost, saves energy, obtains high-quality nano zirconia particles, and lays a foundation for the industrialization process of continuous supercritical hydrothermal / solvothermal synthesis.

[0034] Further, the pipes and elements of the whole system are made of nickel-based alloy or stainless steel titanium lining, which can effectively reduce the impurity problem caused by corrosion and further improve the quality of nano zirconium oxide.

[0035] Further, the high-temperature and high-pressure fluid in the reaction unit is preheated by multi-stage heat exchange for cold fluid and provides steam for the falling film evaporation unit of the product recovery unit, in addition, the waste gas is recycled and combusted to meet the emission standard, and the waste liquid is treated by the membrane treatment unit and the falling film evaporation unit to recover high-value by-products such as potassium sulfate, potassium nitrate and potassium chloride, so as to realize resource utilization of the system. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 The structure diagram of the supercritical hydrothermal and solvothermal synthesis of nano composite zirconia system of the present application.

[0037] Among them: V1 is valve one; V2 is valve two; 1 is composite storage tank one; 2 is composite storage tank two; 3 is low-pressure pump; 4 is precursor storage tank; 5 is solvent storage tank; 6 is additive storage tank; 7 is high-pressure pump one; 8 is high-pressure pump two; 9 is high-pressure pump three; 10 is heater; 11 is mixing unit; 12 is reaction unit; 13 is cooling unit; 14 is slow cooling unit; 15 is pressure reduction unit; 16 is gas-liquid separation unit; 17 is waste gas treatment unit; 18 is solid-liquid separation unit; 19 is drying unit; 20 is nano product storage unit; 21 is membrane treatment unit; 22 is falling film evaporation unit; 23 is additional product storage unit. DETAILED DESCRIPTION

[0038] In order for those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should belong to the scope of protection of the present application.

[0039] It should be noted that the terms "first", "second" and the like in the specification and claims of the present application and the above-described drawings are used to distinguish similar objects, and do not necessarily indicate a specific order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device including a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0040] The application will be described in further detail below with reference to the drawings:

[0041] Referring to Figure 1 The supercritical hydrothermal and solvothermal synthesis nanocomposite zirconia system disclosed by the application comprises a material composite preparation and conveying unit, a heat recycling unit, a post-reaction treatment unit and an additional product recovery unit.

[0042] The material composite preparation and conveying unit comprises composite storage tank one 1, composite storage tank two 2, a low-pressure pump 3, a precursor storage tank 4, a solvent storage tank 5, an additive storage tank 6, a high-pressure pump one 7, a high-pressure pump two 8, a high-pressure pump three 9, a valve one V1 and a valve two V2. The output pipeline of the composite storage tank one 1 and the output pipeline of the composite storage tank two 2 are merged and then enter the precursor storage tank 4 through the low-pressure pump 3. The outlets of the precursor storage tank 4, the solvent storage tank 5 and the additive storage tank 6 are respectively connected with the high-pressure pump one 7, the high-pressure pump two 8 and the high-pressure pump three 9.

[0043] The heat recycling unit comprises a heater 10, a mixing unit 11, a reaction unit 12, a cooling unit 13 and a slow cooling unit 14 connected in sequence. The outlets of the high-pressure pump one 7, the heater 10 and the high-pressure pump three 9 are respectively connected with the mixing unit 11 through pipelines, and the three are merged in the mixing unit 11. The outlet of the cooling unit 13 is divided into two routes, one of which returns to the inlet end of the heater 10, and the other of which is connected with the inlet of the slow cooling unit 14.

[0044] The post-reaction treatment unit comprises a pressure reduction unit 15, a gas-liquid separation unit 16, a waste gas treatment unit 17, a solid-liquid separation unit 18, a drying unit 19 and a nanoproduct storage unit 20. One outlet (cold side outlet) of the slow cooling unit 14 is connected to the inlet of the pressure reduction unit 15. The outlet of the pressure reduction unit 15 is connected with the inlet of the gas-liquid separation unit 16. The outlet of the gas-liquid separation unit 16 is divided into two routes, one of which is connected with the waste treatment unit 17, and the other of which is connected to the inlet of the solid-liquid separation unit 18. The outlet of the solid-liquid separation unit 18 is divided into two routes, one of which is connected to the drying unit 19, and the other of which is connected to the additional product recovery unit. The outlet end of the drying unit 19 is connected to the nanoproduct storage unit 20.

[0045] The additional product recovery unit comprises a membrane treatment unit 21, a falling film evaporation unit 22 and an additional product storage unit 23 connected in sequence. The inlet end of the membrane treatment unit 21 is connected with one outlet of the solid-liquid separation unit 18.

[0046] Preferably, the outlet of the high-pressure pump two 8 is divided into two routes, one of which is connected with the inlet of the heater 10 through the valve one V1, and the other of which is connected with the cooling unit 13 through the valve two V2.

[0047] Preferably, the heater 10 has two inlets and one outlet, one cold side inlet connected with the high pressure pump two 8, and the other hot side inlet connected with the outlet of the cooling unit 13.

[0048] Preferably, the cooling unit 13 includes two inlets and two outlets, wherein the hot side inlet is connected with the outlet of the reaction unit 12, the cold side inlet is connected with the high pressure pump two 8 through the valve two V2, the hot side outlet is connected with the hot side inlet of the heater 10, and the cold side outlet is connected with the hot side inlet of the slow cooling unit 14.

[0049] Preferably, the slow cooling unit 14 includes two inlets and two outlets, wherein the hot side inlet is connected with the cold side outlet of the cooling unit 13, and the cold side inlet is connected with the outlet of the falling film evaporation unit 22; the hot side outlet is connected with the inlet of the falling film evaporation unit 22, and the cold side outlet is connected with the pressure reduction unit 15.

[0050] Preferably, the outlet of the gas-liquid separation unit 10 is divided into two routes, one of which is connected with the waste gas treatment unit 17, and the other is connected with the solid-liquid separation unit 18.

[0051] Preferably, the low pressure pump 3 can be selected from a centrifugal pump, a metering pump, etc.; the high pressure pump one 7, the high pressure pump two 8 and the high pressure pump three 9 can be selected from a diaphragm type or a piston type high pressure pump.

[0052] Preferably, the composite storage tank one 1 and the composite storage tank two 2 before the low pressure pump 3 are not limited to two or more; the heater 10 is not limited to an electromagnetic heater, an infrared heater or a resistance heater, etc.; the mixing unit 11 is not limited to a T-shaped three-way mixer, a jacketed countercurrent mixer and a cross-shaped jet mixer, etc.; the reaction unit 12 is not limited to one or more in series or parallel, such as a tubular reactor or a kettle reactor; the heat exchange form of the cooling unit 13 and the slow cooling unit 14 is not limited to a coil or a jacket, etc.; the membrane treatment unit 21 is not limited to a forward osmosis, a RO reverse osmosis or an ultrafiltration membrane, etc.; the material of the elements used in the system is not limited to a nickel-based alloy, a titanium-lined stainless steel or a non-metallic coating, etc.

[0053] In the composite tank 1, one or more ligands such as PVP, EDTA, etc. are stored, and in the composite tank 2, one or more stabilizers such as yttrium salts, lanthanum salts, cerium salts, etc. are stored. The materials in the two composite tanks are mixed and then fed into the precursor tank 4 through the low-pressure pump 3, mixed with the zirconium precursor (zirconium oxide nitrate, zirconium acetate, zirconium nitrate, or zirconium oxychloride, etc.) and stored in the precursor tank 4. By adjusting the ratio of the ligand and the stabilizer to the zirconium precursor, in-situ control of the crystal form and prevention of agglomeration can be achieved simultaneously. The precursor mixture is pressurized by the high-pressure pump 1 7 to reach the critical pressure value of supercritical hydrothermal synthesis, and the pressurized material is pumped into the mixing unit 1 1. The alkali solution (sodium hydroxide, potassium hydroxide, ammonia water, etc. which can provide hydroxyl ions) in the additive tank 6 is pressurized by the high-pressure pump 3 9 and then pumped into the mixing unit 1 1.

[0054] When the system is initially operated, the valve 1 V1 is opened, and the pure water or other solvents (ethanol, methanol, etc.) in the solvent tank 5 are pressurized by the high-pressure pump 2 8 and then pumped into the heater 10. The pure water or other solvents are quickly heated to a supercritical temperature and then mixed with the alkali solution and the precursor mixture in the mixing unit 1 1. The mixer is not limited to counter-flow mixing, cross-jet mixing, etc. and can be any element that can increase the mixing area and improve the mixing efficiency. After that, the fully mixed solution enters the reaction unit 12 to undergo rapid hydrolysis and dehydration reactions. The reaction unit can change the reaction time according to the actual conditions. Then, the solution is gradually cooled through the cooling unit 13 and the slow cooling unit 14. The cooling unit 13 and the slow cooling unit 14 are not limited to the forms of a jacketed pipe, a coil pipe, or a finned heat exchanger, which are used to increase the heat exchange area and improve the heat exchange efficiency.

[0055] When the system is normally operated, the valve 1 V1 is closed, and the valve 2 V2 is opened. The unheated pure water or other solvents enter the cooling unit 13 and are fully heat-exchanged with the hot fluid after the reaction. After preheating, the water or other solvents enter the heater 10 to be heated to a supercritical state, realizing a heat exchange cycle. The temperature of the hot fluid is reduced from about 400°C to 200-300°C after heat exchange and cooling; the medium-temperature fluid after heat exchange and cooling enters the slow cooling unit 14, uses the residual heat to generate steam for the falling film evaporation unit 22, and is further cooled to enter the pressure reduction unit 15 and the gas-liquid separation unit 16.

[0056] The solid-liquid-gas three-phase mixture after being treated by the pressure reducing unit 15 is divided into two paths in the gas-liquid separation unit 16, the gas phase enters the waste gas treatment unit 17, wherein the waste gas can be used for heating the heater 10 by the gas, the harmful gas is changed into clean gas such as CO2, N2 and H2O and is released, and can also be used for other purposes. After the solid-liquid phase enters the solid-liquid separation unit 18, the solid phase enters the drying unit 19 for drying, and the nano composite zirconia powder with small particle size, good dispersity and high purity is stored in the nano product storage unit 20; the liquid phase enters the membrane treatment unit 21, a large amount of solvent is filtered out, and high-purity additional products (potassium acetate, potassium nitrate, potassium chloride and the like) are obtained through the falling film evaporation unit 22, and the additional products are stored in the additional product storage unit 23 for sale.

[0057] The nano composite zirconia quality regulation method of the nano composite zirconia system synthesized by the supercritical hydrothermal and solvothermal method comprises the following steps:

[0058] 1) The ligand and the stabilizer are respectively stored in the composite storage tank one 1 and the composite storage tank two 2, mixed with the zirconium precursor (oxyzirconium nitrate, zirconium acetate, zirconium nitrate, zirconium oxychloride and the like) in the precursor storage tank 4 and stored in the precursor storage tank 4, the pressure of the material after being pressurized by the high-pressure pump one 7 reaches the critical pressure value of the supercritical hydrothermal synthesis, the material after being pressurized is pumped into the mixing unit 11, and the alkali solution in the additive storage tank 6 is pressurized by the high-pressure pump three 9 and pumped into the mixing unit 11;

[0059] 2) When the system is initially operated, the valve one V1 is opened, the pure water or other solvents in the solvent storage tank 5 are pressurized by the high-pressure pump two 8 and pumped into the heater 10, the pure water or other solvents are rapidly heated to the supercritical temperature, mixed with the alkali solution and the precursor mixture in the mixing unit 11, and then enter the reaction unit 12 to occur rapid hydrolysis and dehydration reaction, and then are gradually cooled through the cooling unit 13 and the slow cooling unit 14;

[0060] 3) When the system is normally operated, the valve one V1 is closed, the valve two V2 is opened, the unheated pure water or other solvents enter the cooling unit 13 and are fully heat-exchanged with the hot fluid after the reaction of step 2), are preheated and enter the heater 10 to be heated to the supercritical state, the heat exchange cycle is realized, and the temperature of the hot fluid is reduced from about 400℃ to 200-300℃ after being cooled;

[0061] 4) The medium-temperature fluid after being heat-exchanged and cooled in step 3) enters the slow cooling unit 14, steam is generated by using the waste heat for the falling film evaporation unit 22, and then enters the pressure reducing unit 15 and the gas-liquid separation unit 16 after being further cooled;

[0062] 5) The solid-liquid-gas three-phase mixture after step 4) is divided into two routes in the gas-liquid separation unit 16, the gas phase enters the waste gas treatment unit 17, wherein the waste gas can be used for gas heating to supply the heater 10, or can be used for other purposes. The solid-liquid phase enters the solid-liquid separation unit 18, and the solid phase enters the drying unit 19 after drying, and the nano composite zirconia powder is stored in the nano product storage unit 20; the liquid phase enters the membrane treatment unit 21, and after filtering a large amount of solvent, the high-purity additional product (acetate, nitrate, chloride, etc.) is obtained through the falling film evaporation unit 22, and the additional product is stored in the additional product storage unit 23 for sale.

[0063] 6) By changing the ratio of ligands and stabilizers to zirconium-based precursors in composite tank one 1 and composite tank two 2 in 1), the crystal form can be controlled and agglomeration can be prevented; by changing the ratio of alkali solution to zirconium-based precursors in the additive tank 6 in 2), the pH is adjusted, and the temperature, pressure are changed by controlling the electric heating power and pressure set value, and the particle size of the nano zirconia particles is controlled by changing the form of the reaction unit 12, so as to realize the quality control of the nano zirconia as a whole.

[0064] The supercritical hydrothermal / solvothermal synthesis of nano composite zirconia system of the application can fully heat cycle the high-temperature and high-pressure fluid in the reaction unit, provide heat for the unreacted fluid and by-product recovery unit through multi-stage heat exchange, realize heat recovery and cascade utilization, match the energy level as much as possible in the process of heat energy utilization, and maximize the use of low-grade heat energy, thereby reducing system energy consumption and operation cost, improving system economy and stability, in addition, the membrane treatment and falling film evaporation unit in the additional product recovery unit are used for recovering high-value by-products such as potassium sulfate, potassium nitrate and potassium chloride, realizing resource utilization of the system, green economy and high efficiency. The design of the whole system provides certain conditions for large-scale batch production of nano composite zirconia, and accelerates the industrialization process. Of course, the composite tank one and the composite tank two of the application are not limited to be placed before the precursor tank, but can also be placed between the high-pressure pump and the mixing unit, and the membrane treatment unit and the falling film evaporation unit can also be interchanged according to the needs, that is, the order of the process is not limited to the above, and the reasonable and efficient cascade utilization is carried out according to the quality of the waste heat, and reasonable recovery is carried out according to the needs of recovery.

[0065] The above content only illustrates the technical idea of the application, and cannot limit the protection scope of the application. Any modification made according to the technical idea of the application on the basis of the technical scheme falls within the protection scope of the claims of the application.

Claims

1. A system for supercritical hydrothermal and solvothermal synthesis of nanocomposite zirconia, characterized by, It comprises a material complex preparation and conveying unit, a heat recycling unit, a post-reaction treatment unit and an additional product recovery unit. The material complex preparation and conveying unit comprises a complex tank one (1) for adding ligands, a complex tank two (2) for adding stabilizers, a precursor tank (4), a solvent tank (5) and an additive tank (6), the outlet ends of the complex tank one (1) and the complex tank two (2) are connected to the inlet end of the precursor tank (4) through a low-pressure pump (3), high-pressure pumps one (7), two (8) and three (9) are respectively arranged on the outlet pipelines of the precursor tank (4), the solvent tank (5) and the additive tank (6) and are used for conveying materials; The heat recycling unit comprises a heater (10), a mixing unit (11), a reaction unit (12), a cooling unit (13) and a slow cooling unit (14) connected in sequence, the outlets of the high-pressure pump one (7), the heater (10) and the high-pressure pump three (9) are gathered in the mixing unit (11) through pipelines, the outlet of the cooling unit (13) is divided into two paths, one of which is connected to the first inlet of the heater (10) and the other of which is connected to the hot side inlet of the slow cooling unit (14), the outlet of the high-pressure pump two (8) is divided into two paths, one of which is connected to the second inlet of the heater (10) through a valve one V1 and the other of which is connected to the cooling unit (13) through a valve two V2; The outlet of the slow cooling unit (14) is divided into two paths, one of which is connected to the post-reaction treatment unit and the other of which is connected to the additional product recovery unit; The post-reaction treatment unit is used for treating the zirconia oxide nano product obtained by reaction, comprises a pressure reduction unit (15), a gas-liquid separation unit (16), a waste gas treatment unit (17), a solid-liquid separation unit (18), a drying unit (19) and a nano product storage unit (20), the cold side outlet of the slow cooling unit (14) is connected to the inlet of the pressure reduction unit (15), the outlet of the pressure reduction unit (15) is connected to the inlet of the gas-liquid separation unit (16), the outlet of the gas-liquid separation unit (16) is divided into two paths, one of which is connected to the waste gas treatment unit (17) and the other of which is connected to the inlet of the solid-liquid separation unit (18), the outlet of the solid-liquid separation unit (18) is divided into two paths, one of which is connected to the drying unit (19) and the other of which is connected to the additional product recovery unit, the outlet of the drying unit (19) is connected to the nano product storage unit (20); The additional product recovery unit is used for recovering additional products, comprises a membrane treatment unit (21), a falling film evaporation unit (22) and an additional product storage unit (23) connected in sequence, the inlet of the membrane treatment unit (21) is connected to one of the outlets of the solid-liquid separation unit (18), the hot side outlet of the slow cooling unit (14) is connected to one of the inlets of the falling film evaporation unit (22), one of the outlets of the falling film evaporation unit (22) is connected to the slow cooling unit (14) through a pipeline.

2. The supercritical hydrothermal and solvothermal synthesis of nanocomposite zirconia system of claim 1, wherein, A plurality of complex agent storage tanks are arranged on the pipeline before the low-pressure pump (3) for sub-packaging ligand and / or stabilizer, and the outlets of all the complex agent storage tanks are connected to the precursor storage tank (4) through the low-pressure pump (3).

3. The supercritical hydrothermal and solvothermal synthesis of nanocomposite zirconia system of claim 1, wherein, The heater (10) is an electromagnetic heater, an infrared heater or a resistance heater; the mixing unit (11) is a T-shaped three-way mixer, a jacketed counter-flow mixer or a cross-shaped jet mixer.

4. The supercritical hydrothermal and solvothermal synthesis of nanocomposite zirconia system of claim 1, wherein, The reaction unit (12) is a tubular reactor or a kettle reactor, and one reactor is arranged or a plurality of reactors are connected in series or in parallel; the cooling unit (13) and the slow cooling unit (14) are coil pipe heat exchangers or jacketed heat exchangers.

5. The supercritical hydrothermal and solvothermal synthesis of nanocomposite zirconia system of claim 1, wherein, The pipeline and the reaction element of the system are made of nickel-based alloy or stainless steel titanium lining.

6. The method for quality control of nanocomposite zirconia based on the supercritical hydrothermal and solvothermal synthesis of nanocomposite zirconia system according to any one of claims 1 to 4, characterized in that, The system comprises: The ligand is stored in the complex storage tank one (1), the stabilizer is stored in the complex storage tank two (2), and the mixture is pumped into the precursor storage tank (4) through the low-pressure pump (3) for mixing and storage, the pressure of the mixture is increased to the critical pressure value of the supercritical hydrothermal synthesis through the high-pressure pump one (7), the pressurized mixture is pumped into the mixing unit (11), the alkali solution in the additive storage tank (6) is pressurized through the high-pressure pump three (9) and then pumped into the mixing unit (11); The valve one V1 is opened, the solvent in the solvent storage tank (5) is pressurized by the high-pressure pump two (8) and then pumped into the heater (10), the solvent is heated to the supercritical temperature and then introduced into the mixing unit (11), the solvent, the alkali solution and the precursor mixture in the mixing unit (11) are fully mixed, and then the mixture is introduced into the reaction unit (12) to generate hydrolysis and dehydration reactions, and then the mixture is gradually cooled through the cooling unit (13) and the slow cooling unit (14); The valve one V1 is closed, and the valve two V2 is opened, the unheated solvent is introduced into the cooling unit (13) to exchange heat with the hot fluid after the reaction in step 2), the preheated solvent is introduced into the heater (10) to be heated to the supercritical state, the heat exchange cycle is realized, the temperature of the hot fluid is reduced from 400 DEG C to 200-300 DEG C after heat exchange, the medium-temperature fluid after heat exchange is introduced into the slow cooling unit (14), the steam generated by the waste heat is used for the additional product recovery unit, and the medium-temperature fluid is further cooled and then introduced into the reaction post-processing unit.

7. The method of claim 6, wherein the method is characterized by, The solid-liquid-gas three-phase mixture introduced into the reaction post-processing unit is separated into two paths in the gas-liquid separation unit (16), the gas phase is introduced into the waste gas treatment unit (17), the waste gas is used for gas heating to supply the heater (10), the solid-liquid phase is introduced into the solid-liquid separation unit (18), the solid phase is introduced into the drying unit (19) for drying, the obtained nano composite zirconia powder is stored in the nano product storage unit (20), and the liquid phase is introduced into the membrane treatment unit (21), the solvent is filtered out, and then the high-purity additional product is obtained through the falling film evaporation unit (22), and the high-purity additional product is stored in the additional product storage unit (23).

8. The method for quality control of nano-composite zirconia according to claim 6, characterized in that, The system comprises: The proportion of the ligand and the stabilizer in the complex storage tank one (1) and the complex storage tank two (2) and the zirconium precursor is changed to control the particle anti-agglomeration and the crystal form of the product. The pH value is adjusted by changing the ratio of alkali solution and zirconium precursor in the additive storage tank (6), the reaction temperature and pressure are changed by controlling the electric heating power and pressure set value, and the reaction time is changed by changing the number and connection form of the reactors of the reaction unit (12) to control the particle size of the nano zirconia particles. The pipes and elements of the whole system are made of nickel-based alloy or stainless steel titanium lining material to prevent impurities from corrosion of the system and control the purity of the nano zirconia particles.

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