A process for the digestion and separation of aluminium fluoride

Abstract

The application discloses a method for digesting and separating fluorinated aluminum by program, which comprises the following steps: placing a catalyst with metal elements supported on alumina as a carrier into a reaction container of a cluster digestion device, adding hydrochloric acid and / or nitric acid, setting a digestion program, introducing inert gas for pre-pressurization, performing primary digestion, and simultaneously starting a condensation reflux atomizer; after the program is completed, adding hydrofluoric acid, setting a digestion program, and performing secondary digestion; after the digestion is completed, entering a cooling and crystallization program, performing cooling and crystallization, and separating to obtain a sample solution to be detected and a solid; the solid is dried and calcined to obtain fluorinated aluminum crystals, and the liquid is used for detecting the content of metal elements. The method is applied to the digestion treatment of the alumina sample with metal elements supported thereon, has a large sample treatment range, complete digestion, no volatile loss of elements, and can separate AlF3 in an alpha crystal form through the program digestion of the digestion device.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of digestion and the technical field of chemical separation, and particularly relates to a method for separating aluminum fluoride by program digestion. BACKGROUND

[0002] Microwave is an electromagnetic wave with a frequency of 300MHz-300000MHz, i.e. an electromagnetic wave with a wavelength of 100cm-0.1cm, also known as ultra-high frequency, located between infrared radiation and radio wave in the electromagnetic spectrum. It has been widely applied in the fields of food, textile, plastic, geology, metallurgy, coal, biological medicine, petroleum chemical industry, environmental monitoring, sewage treatment, battery manufacturing, cosmetics, etc. The microwave frequencies used in industry mainly include 915±25MHz, 2450±13MHz, 5800±75MHz, 22125±125MHz, etc. Among them, the widely used frequency is 2450±13MHz, and the output power is 600W-800W, which can release about 200kJ of energy in a few minutes, so that the molecules of the medium produce about 2.4 billion five million vibrations per second, the molecules of the medium produce friction with each other, causing the temperature of the medium to rise, so that the internal and external of the medium material are heated and rise at almost the same time, forming a body heat source state, greatly shortening the heat conduction time in conventional heating, and when the condition is that the medium loss factor is negatively correlated with the medium temperature, the internal and external of the material are heated uniformly.

[0003] At present, the widely used microwave digestion instrument mainly utilizes the heating advantages and characteristics of microwave. After the sample to be digested in the special plastic digestion tank is added with acid to form a strong polar solution, the solution is heated simultaneously inside and outside by utilizing the body heating property of microwave, so that the heating is faster and more uniform, and the efficiency is improved. Microwave digestion is generally carried out in a closed digestion tank, and the pressure system can produce overheating phenomenon, so that the heating temperature is higher than the boiling point under normal pressure, which greatly improves the digestion speed and can digest samples that cannot be digested by general wet digestion. Microwave digestion in a closed system can prevent the loss of volatile elements and perform some projects that cannot be performed by conventional wet digestion. However, the traditional closed microwave digestion device has a limited sample processing capacity, and the organic sample is generally not more than 0.5g, and the inorganic sample is generally not more than 1.0g. The traditional ultra-high pressure digestion reaction tank has a large batch processing capacity, is suitable for processing large batches of samples, and has a solid furnace cavity and is not easy to deform; however, it has high energy consumption, large volume, high price, high use and maintenance cost, and low safety factor.

[0004] In addition, the uneven distribution of microwave field in common microwave digestion chambers can lead to uneven microwave reception of samples within the chamber, affecting the digestion effect. The usual solution is to rotate the tray to ensure that each sample receives microwaves as evenly as possible. However, the temperature and pressure changes of the samples before and after heating during the cycle are relatively large, and the turntable design cannot fix the digestion vessel, which is a certain deficiency from a safety point of view.

[0005] Based on the power transmission method, microwaves are divided into pulsed microwaves and non-pulsed microwaves. Traditional fixed power output is characterized by on / off pulsed microwaves. This control method is not only difficult to control but may also directly affect the digestion effect. The current development trend of microwaves is automatic power frequency conversion control and non-pulsed technology. Its characteristics are automatic power variation and non-pulsed microwave output. Its advantages are that there is no need to shut down microwave transmission. Under continuous microwave transmission conditions, the microwave power output is automatically and linearly changed according to temperature and pressure feedback signals to adjust the reaction state, resulting in more accurate temperature control and ensuring the safe and smooth conduct of experiments.

[0006] Alumina-based catalysts are catalysts that use alumina as a support, immobilizing active components such as nickel, cobalt, molybdenum, platinum, palladium, or their oxides onto the alumina. Over 70% of active alumina is used as a catalyst support, and it is widely used in the petroleum refining and chemical industries. Alumina is one of the most commonly used industrial raw materials, with extremely important applications in ceramics, refractories, pharmaceuticals, and catalysis. Due to its excellent mechanical strength, good thermal and chemical stability, suitable isoelectric point, tunable surface acidity and alkalinity, and various crystal phase structures, alumina has become the most widely used catalyst support in the chemical and petroleum industries. It plays a crucial role in reactions such as petroleum component cracking, hydrorefining, hydrodesulfurization, hydrocarbon reforming for hydrogen production, purification of gaseous oil components, and purification of automobile exhaust.

[0007] As a catalyst support, alumina support refers to white powdery or formed solid alumina, and it is one of the most widely used catalyst supports, accounting for approximately 70% of supported catalysts in industry. In many industrial catalytic processes, alumina is not only used as a catalyst itself, but also extensively used as a support for the active components of the catalyst. Moreover, with the improvement of the forming methods of activated alumina catalyst supports, various methods have been applied to the catalyst support industry, such as briquetting, granulation, compaction, pelletizing, and extrusion. Therefore, it can be used as a catalyst support in various shapes, such as columnar, ring-shaped, spherical, tablet-shaped, granular, and extruded strip-shaped.

[0008] Traditional methods for analyzing the chemical composition of alumina-based catalysts typically employ alkali metal carbonates or hydroxides such as K₂CO₃ or Na₂CO₃ as co-solvents. These are then melted together with the alumina sample in a platinum dish at 1000°C. While the Al element dissolves, K₂CO₃ is also introduced as a co-solvent.+ Na + elements, resulting in increased detection background, increased matrix interference, and affecting the accuracy of the detection. Methods for determining metal content generally include plasma emission spectrometry, spectrophotometry, X-ray fluorescence spectrometry, atomic absorption spectrometry, and plasma emission spectrometry. Among them, plasma emission spectrometry has the advantages of high accuracy, fast analysis speed, and wide linear range. Plasma emission spectrometry includes plasma atomic emission spectrometry and plasma emission mass spectrometry.

[0009] The commonly used method for eliminating interference in spectral analysis is matrix matching or internal standard method, which aims to eliminate the influence of analysis condition fluctuations on the intensity of the analysis line. For example, Ye Yuqiong et al. proposed in "Simultaneous Determination of Platinum and Phosphorus in Alumina-based Catalysts by Atomic Emission Spectrometry" published in Metallurgical Analysis in 1993 that atomic emission spectrometry powder method should be used, the best electrode shape should be selected, spectral corrosion inhibitor and internal standard element should be added, and determination should be carried out. Cheng Xichun et al. proposed in "Determination of Palladium Content in Alumina-based Catalysts by ICP-AES Internal Standard Method" published in Fujian Analysis and Testing in 2016 that aqua regia (15 mL of concentrated nitric acid and 45 mL of concentrated hydrochloric acid) should be used to dissolve the sample, yttrium should be used as the internal standard element for determination.

[0010] The sampling quality of existing microwave digestion instruments for processing solid samples is usually limited, mainly due to the constraints of digestion container size, digestion chamber design, etc. Therefore, for the analysis of trace and ultra-trace elements in solid samples, the existing microwave digestion instrument is difficult to meet the requirements of the determination. Therefore, the design of microwave digestion instrument using large-volume digestion containers and digestion chambers for efficient digestion is worth further research and development.

[0011] In addition, according to the characteristics of the instrument used for element testing, matrix matching or internal standard method is not suitable for high concentration matrix, especially for the determination of low content impurity metals, which still has different degrees of influence, making the determination results unable to meet the accuracy requirements of the method.

[0012] Through experimental research, it is found that the aluminum element concentration in the dissolved alumina solution is 40% to 60%, which causes serious spectral interference when determining the loaded metal elements. For example, when determining Pt element in Pt-loaded Al2O3-based catalyst, Pt analysis spectral lines are 265.945 nm and 214.423 nm. If Al matrix is dissolved in the sample, Pt analysis spectrum will be cut off due to the interference of Al matrix, resulting in low determination results.

[0013] Currently, among the synthesis technologies for aluminum fluoride, there are various crystal forms such as α-AlF3, β-AlF3, and γ-AlF3, each with different formation conditions. For example, CN95115476, "Fluorination Catalysts for Fluorinated Halogenated Hydrocarbons," proposes using SiO2 to fluorinate γ-Al2O3 with a mixture of anhydrous hydrogen fluoride and nitrogen, as well as pure wastewater hydrogen fluoride, at 150℃~300℃. This is used as a catalyst for supporting chromium, cobalt, and magnesium catalysts to synthesize fluorination catalysts for fluorinated halogenated hydrocarbons.

[0014] Chinese patent CN2748147Y discloses an ultrasonic microwave digestion and extraction device, comprising: a housing, a magnetron, a waveguide, sample vials, a microwave power supply, a reflux condenser, a condenser sleeve, and an electronic control system. The electronic control system is a microcontroller. The housing is a hexahedron made of metal plates, with a hinged door on the front. A microwave radiation cavity is formed inside the housing by a metal partition, and the sample vials are placed in the microwave radiation cavity. One end of the reflux condenser is inserted into the mouth of the sample vials through a sleeve fixed to the top of the housing by a nut, and is fixed to the top of the housing by a positioning ring. This technology installs ultrasonic and microwave on the housing, and the housing structure is a conventional hexahedron. Ordinary housing structures and conventional microwave functions may result in incomplete digestion of large-mass samples. In addition, although this technology includes a reflux condenser, volatile elements are prone to remain in the reflux tube wall, and cooling alone cannot completely and effectively reflux the volatile residues.

[0015] Chinese patent CN205301023U discloses an atmospheric pressure sealed pollution-free digester, which consists of a ground-glass stoppered triangular flask, a vertical condenser, an anti-backflow bottle, a toxic gas absorption bottle, and a perforated plate. Its key feature is that the vertical condenser is connected to the top of the ground-glass stoppered triangular flask, and the upper side of the vertical condenser is connected to the anti-backflow bottle via a gas guide tube. The anti-backflow bottle is connected to the toxic gas absorption bottle via a gas guide tube, and the outlet of the gas guide tube is sealed by the perforated plate and extends downwards to near the bottom of the toxic gas absorption bottle. A certain amount of toxic gas absorbing liquid is added to the toxic gas absorption bottle, which isolates the sample solution to be digested from the ambient air. However, this technology only provides a device for digestion via conventional bottom heating and condensation. Conventional sealed heating digestion is difficult to meet the requirements for digesting large-mass oxide samples loaded with a large amount of metal elements.

[0016] Existing microwave digestion equipment typically offers limited sampling quality for solid samples, primarily due to constraints such as digestion vessel size and digestion chamber design. Therefore, existing microwave digestion equipment struggles to meet the requirements for analyzing trace and ultra-trace elements in solid samples. Consequently, the design of microwave digesters utilizing large-volume digestion vessels and multi-internal-surface digestion chambers to achieve efficient digestion warrants further research and development. Summary of the Invention

[0017] The present application aims to provide a method for digestion and separation of aluminum fluoride, which is applied to the digestion treatment of catalyst samples with metal supported on alumina carrier, has a large sample treatment range, complete digestion, no volatile loss of elements, and separates AlF3 in alpha crystal form through the program digestion of the digestion device.

[0018] To achieve the above-mentioned purpose, the present application provides a method for digestion and separation of aluminum fluoride, which comprises: placing a catalyst with metal elements supported on alumina carrier into a reaction container of a cluster digestion device, adding hydrochloric acid and / or nitric acid, setting a digestion program, introducing inert gas pre-pressurization, performing primary digestion, and simultaneously starting a condensation reflux atomizer; after the program ends, adding hydrofluoric acid, setting a digestion program, and performing secondary digestion; after the digestion is completed, entering a cooling crystallization program, performing cooling crystallization, separating to obtain a clear sample solution and a solid, drying and calcining the solid to obtain aluminum fluoride crystals, and using the sample solution for detection of the content of metal elements;

[0019] The cluster digestion device comprises: a body, a reaction container, and a condensation reflux atomizer; the condensation reflux atomizer comprises a condenser inlet, a reflux pool, a reflux pool outlet, a condensation tube, an atomizer generator, a condenser water inlet, and a condenser water outlet, the lower end of the condensation tube is in communication with the reflux pool, and the side of the reflux pool is in communication with the atomizer generator through a sealing ring; the bottom of the condensation reflux atomizer is provided with a condenser lower outlet, and the condenser lower outlet is in communication with the reaction container;

[0020] The atomizer generator is a glass concentric atomizer, the center of which is a capillary tube, the capillary tube is parallel to the gas flow of a carrier gas, the carrier gas is introduced through an external gas inlet port on one side of the body, the gas flow rapidly passes through the end of the capillary tube, meets and shears the liquid in the atomizer generator at the atomizer nozzle, forms tiny droplets, the tiny droplets are sprayed out with the carrier gas, condenses into condensate through the condensation tube, the condensate droplets reflux into the reflux pool, and flow into the reaction container; the upper part of the reaction container is provided with an external port, which is in communication with an external inert gas.

[0021] Further, the metal elements include at least one of nickel, cobalt, molybdenum, platinum, palladium, lead, iridium, and ruthenium.

[0022] Further, the content of alumina in the catalyst is 10wt%-98wt%, the catalyst is ground to have a particle size less than 74μm to obtain the best reaction effect, and the catalyst is dried at 105℃-120℃ for 100min-150min, cooled, and then placed into the reaction container of the cluster digestion device.

[0023] Further, the atomization generator uses carrier gas, which is at least one of nitrogen, helium and argon, with a flow rate of 0.05-1.0 L / min and a pressure of 0.1-0.5 MPa; the carrier liquid is a dilute acid solution; the dilute acid solution is selected from hydrochloric acid and / or nitric acid, with a mass concentration of 0.5-5.0%, and the flow rate of the carrier liquid is 0.1-2.5 mL / min.

[0024] Further, the inert gas is at least one of nitrogen, helium and argon, with a flow rate of 0.5-2.0 L / min and a pressure of 0.5-5.0 MPa.

[0025] Further, the hydrochloric acid and / or nitric acid is added in a proportion of 5.0 mL-10.0 mL acid per 1.0 g catalyst, the catalyst is added in an amount of 1.0 g-50.0 g, the mass concentration of the hydrochloric acid is 10%-37%, and the mass concentration of the nitric acid is 40%-68%; when both hydrochloric acid and nitric acid are added, the proportion of hydrochloric acid to nitric acid is 1:1-4:1; the temperature of the primary digestion is 120°C-200°C, the pressure is less than 5.0 MPa, and the time is 30 min-120 min.

[0026] Further, the hydrofluoric acid is added in a proportion of 5.0 mL-10.0 mL hydrofluoric acid per 1.0 g catalyst, the catalyst is added in an amount of 1.0 g-50.0 g, the mass concentration of the hydrofluoric acid is 20%-40%, the temperature of the secondary digestion is 80°C-180°C, the pressure is less than 5.0 MPa, and the time is 30 min-120 min; the temperature of the crystallization is 15°C-25°C, and the time is 120 min-240 min.

[0027] Further, the drying temperature is 105°C-120°C, the calcination temperature is 450°C-600°C, and the time is 100 min-200 min; the aluminum fluoride crystal is an α-type AlF3 with a specific surface area greater than 40 m 2 / g and a pore size greater than 50 angstroms.

[0028] Further, the machine body comprises a chamber, a front machine door, an upper machine door, a display screen, a control panel, a base, a microwave generating system, the chamber is located inside the machine body and is opened or closed by the front machine door, the cavity structure is a polyhedron, the left and right faces and the front and back faces are respectively or both symmetrical faces, or the diagonal faces are symmetrical, and the upper and lower faces are symmetrical faces, and are composed of at least 8 inner surfaces; the upper machine door is located at the top of the machine body, the display screen and the control panel are located on the top surface or one side surface of the machine body, the microwave generating system is connected to the chamber, and the base does not adopt a turntable type, but adopts a bottom disc fixed to the bottom surface of the chamber; the reaction container is placed on the base of the chamber; the outside of the machine body is connected with an external gas inlet port and a gas cylinder.

[0029] Further, the carrier gas in the atomization generator is an inert gas, which is at least one of nitrogen, helium and argon, the flow rate is 0.05-1.0 L / min, and the pressure is 0.1-0.5 MPa; the carrier liquid is a dilute acid solution, the dilute acid solution is hydrochloric acid and / or nitric acid, the mass concentration of the hydrochloric acid and / or nitric acid is 0.5-5.0%, and the flow rate of the carrier liquid is 0.1-2.5 mL / min.

[0030] Further, the chamber is a closed rectangular industrial resonant cavity; the material of the chamber is all stainless steel or polytetrafluoroethylene, and is provided with a plurality of layers of anticorrosion coating; the polytetrafluoroethylene can resist corrosion of acid, alkali, organic solvent and the like; the chamber is also provided with an exhaust system and a cooling system, and the exhaust capacity in the chamber is not less than 1.0 m 3 / min. The chamber can also be installed with a forced air cooling function to continuously cool the reaction container and display the temperature and pressure in real time.

[0031] Further, the machine door is provided with double or triple independent interlocking sensing equipment, the power is cut off when the machine door is opened, and the microwave generating system cannot work when the machine door is not closed; the machine door is also provided with an observation window, the outside of the machine body is provided with a heat dissipation net, and the mesh of the metal grid or wire mesh in the observation window and the heat dissipation net is 0.02-0.2 mm.

[0032] Further, the machine body can be designed into one module or multiple modules, which is not limited to the two modules shown in Figure 1 the figure, and the reaction conditions of each module can be controlled through a program.

[0033] Further, the shape of the reaction container is selected from one of a spherical type, a cylindrical type, a cubic type and a polyhedral type.

[0034] Further, the material of the reaction container is one of PTFE, PFA, TFM and quartz, which can be penetrated and propagated by microwaves, so that the material does not absorb or only a little absorbs the energy of microwaves, and the penetration of microwaves enhances the ability of the sample in the reaction container to absorb microwaves.

[0035] Further, the outer wall of the reaction container wall is a waveguide layer, which is helpful to the penetration of microwaves and good temperature conduction, and the material thereof should be a non-polar molecular substance. Due to the accelerated transformation of the frequency of microwaves, the molecules tend to collide and rub with each other, and the reaction is violent. In order to improve the safety of operation, the material with small deformation, small permeability, good high-temperature and high-pressure recovery and high surface finish under high temperature can be selected. For example, PEEK is a special engineering plastic with excellent properties such as high temperature resistance, self-lubrication, easy processing and high mechanical strength. The waveguide layer adopts PEEK fiber containing more than 10% carbon fiber or more than 10% glass fiber, but is not limited thereto. Other new materials with high temperature resistance and high mechanical strength can also be used, but are not limited thereto.

[0036] Further, the volume of the reaction container is 200 mL to 2000 mL; and the working temperature of the reaction container is 0 to 350℃, and the internal pressure can reach 5.0 Mpa at the highest temperature.

[0037] Further, the reagent is introduced into the reaction container, and the reagent is acid, base or other reagent required for digestion. The acid is at least one of hydrochloric acid, nitric acid, phosphoric acid, hydrofluoric acid, hydrobromic acid, hydroiodic acid, sulfuric acid, perchloric acid, boric acid, oxalic acid, tartaric acid and citric acid. The base is at least one of ammonia and sodium hydroxide, and the other reagent required for digestion is hydrogen peroxide.

[0038] Further, the chamber is provided with an optical fiber temperature sensor, and the chamber is controlled by an optical fiber, which is not interfered by a microwave field, has high measurement accuracy and good safety. The temperature control range is 0 to 350℃, and the temperature control accuracy is ±0.5℃.

[0039] Further, the internal components between the chamber and the body are a magnetic control device, a diode, a refrigerator, a transformer and a fan.

[0040] Further, the microwave frequency of the microwave source of the microwave generating system is 2450 MHz, and the microwave output power is 0 to 1600 W, which is automatically and continuously adjustable. The microwave of the microwave generating system is a non-pulsed continuous automatic frequency control, has a long service life and good uniformity of emitted electromagnetic waves.

[0041] Further, the control system adopts a high-precision temperature and pressure control system, and an operator can observe the data and curve of temperature and pressure changes through a control panel to understand the machine operation, monitor the temperature and pressure in real time, and ensure safety.

[0042] Further, the refrigerator is a semiconductor refrigerator for cooling the inside of the chamber, and the working temperature is 0 DEG C to 25 DEG C, and the control temperature is 15 DEG C to 20 DEG C.

[0043] Further, the air outlet is mounted on the side of the body.

[0044] The application also provides a method for detecting the content of metal elements in a catalyst, which digests the catalyst by the above method, separates aluminum fluoride, and then determines the content of each metal element.

[0045] The reaction container is placed in the chamber and on the base, and is fixed in the chamber through a fixing ring and a screw; the working of the whole microwave digestion device is controlled through a control panel, and the display screen displays all programs in real time; the device is started, and the front door and the upper door are automatically locked and cannot be manually opened; the transformer supplies the diode with power, the diode is connected with the magnetic controller, and the diode sends microwaves to the chamber through the cavity layer to form microwave aggregation in the chamber, and the microwave aggregation acts on the reaction container; the temperature sensor probe and the pressure sensor probe in the chamber monitor the changes of the temperature and the pressure in the chamber in real time; the volatile gas leaked in the chamber is discharged through the fan, the fan is connected with the air outlet on the side of the body, and the residual heat in the chamber is dissipated through the heat dissipation net on the side of the body.

[0046] The method for separating aluminum fluoride by program digestion of the application can realize the aggregation of microwaves in the transmission path, greatly improve the efficiency of microwaves, realize the digestion of the sample under micro-pressure or low pressure through high-efficiency radiation, obtain complete digestion at the aggregation position, improve the operation safety, accelerate the digestion speed, and process a large amount of samples at one time, thereby greatly improving the deficiency of small sample amount in the existing microwave digestion.

[0047] The method for digesting and separating fluorinated aluminum by the program of the application is to directly act the microwave aggregation on the sample, to carry out high efficient radiation, to digest the sample under micro pressure and low pressure, and to operate safely. The microwave aggregation can accelerate the reaction speed, reduce the reagent consumption, and improve the reaction efficiency. The volume of the chamber is large, and the sample amount can be treated at one time, which improves the problem of small sample amount and difficult enrichment of low content sample in the existing digestion device. The high temperature and high pressure generated in the traditional microwave sealed digestion reaction can make many elements and compounds in the gaseous state, and if the sealing effect is not good, it can cause serious element loss and affect the consistency of sample digestion. The design of condensation, atomization and reflux solves the problem of volatile element loss, the volatile residual phase attached to the wall of the condenser is dissolved by the small mist droplets sprayed by the condensation, atomization and reflux atomizer, is condensed through the condenser, and the condensed droplets flow back into the reflux pool and into the reactor. At the same time, the application does not need to use the rotating disc type, and the fixed bottom disc design is stable and safe.

[0048] When the reaction is abnormal, the buffer structure ensures the personal safety of the operator and the integrity of the furnace door structure, the cavity door and the cavity are tightly combined, and there is no microwave leakage. The microwave digestion device adopts a temperature and pressure double control system to control the internal pressure and temperature, and displays in real time. When the pressure in the reaction container exceeds the set protection value, the microwave will automatically stop heating. A high-precision temperature and pressure control system is adopted, and the operator can understand the machine operation condition by observing the data and curve of temperature and pressure change. The software module can actively stop running when the slope is out of control, which greatly reduces the possibility of tank explosion. It has real-time temperature and pressure abnormality monitoring, and when the high-precision temperature and pressure control system fails, the system serves as a backup measure to sense and stop running in time, ensuring safety.

[0049] The microwave digestion device mainly comprises a body, a reaction container and a condensation, atomization and reflux atomizer. Before the reaction, the sample is added to the reaction container, the reaction container is placed in the chamber and fixed, the condensation, atomization and reflux atomizer is connected, and the condensation, atomization and reflux atomizer is started at the same time. The acid reagent required for digestion reaction is introduced through the inlet of the condensation, atomization and reflux atomizer. During the sample digestion process, instantaneous reaction may be violent, which can cause element volatilization. Therefore, the condensation, atomization and reflux atomizer should be started in advance before the digestion reagent is introduced, so as to prevent instantaneous volatilization and avoid element loss. The control panel is opened, the reaction temperature, time and pressure are set, the parameter setting is completed, the program is started, the digestion device starts to work, the carrier gas is started and the carrier liquid is introduced, the atomization generator works, and the volatile phase remaining on the wall of the condenser is atomized into extremely fine mist droplets by the atomization generator under the action of condensation, and returns to the reaction container.

[0050] The method for digesting and separating fluorinated aluminum by the program of the application is to directly act the microwave aggregation on the sample, to carry out high efficient radiation, to digest the sample under micro pressure and low pressure, and to operate safely. The microwave aggregation can accelerate the reaction speed, reduce the reagent consumption, and improve the reaction efficiency. The volume of the chamber is large, and the sample amount can be treated at one time, which improves the problem of small sample amount and difficult enrichment of low content sample in the existing digestion device. The design of condensation, atomization and reflux solves the problem of volatile element loss, the volatile residual phase attached to the wall of the condenser is dissolved by the small mist droplets sprayed by the condensation, atomization and reflux atomizer, is condensed through the condenser, and the condensed droplets flow back into the reflux pool and into the reactor. At the same time, the application does not need to use the rotating disc type, and the fixed bottom disc design is stable and safe.

[0051] The method for digesting and separating fluorinated aluminum by programmed digestion of the application can digest a large amount of samples, is suitable for digestion of low-content samples, and greatly reduces the detection limit of samples through the design of a large-volume digestion reaction container.

[0052] The method for digesting and separating fluorinated aluminum by programmed digestion of the application works under micro-pressure or low pressure, improves the safety of the digestion reaction, and effectively avoids the safety hazards brought by high-pressure reaction to the digestion process.

[0053] The method for digesting and separating fluorinated aluminum by programmed digestion of the application can separate alpha-type fluorinated aluminum crystals which are stable in nature.

[0054] The method for digesting and separating fluorinated aluminum by programmed digestion of the application can completely dissolve the metal elements loaded in the aluminum oxide catalyst.

[0055] The method for digesting and separating fluorinated aluminum by programmed digestion of the application effectively removes the interference problem of the aluminum matrix to the spectral analysis after separating fluorinated aluminum, and is simple and easy to operate. BRIEF DESCRIPTION OF DRAWINGS

[0056] Figure 1 is the external structure front view of the set condensation digestion device of the application;

[0057] Figure 2 is the structure schematic diagram of the condensation reflux atomizer of the application;

[0058] Figure 3 is the internal structure cross-sectional view of the chamber of the application;

[0059] Figure 4 is the schematic diagram of the reaction container fixing ring of the application;

[0060] Figure 5 is the internal component installation schematic diagram between the chamber and the body of the application;

[0061] Figure 6 is the structure schematic diagram of the atomization generator of the application;

[0062] Figure 7 is the XRD spectrum of the alpha-AlF3 product obtained in Example 1;

[0063] Figure 8 is the SEM image of the alpha-AlF3 product obtained in Example 1 (magnification: 800);

[0064] Figure 9 is the XRD spectrum of the alpha-AlF3 product obtained in Example 2;

[0065] Figure 10 is the SEM image of the alpha-AlF3 product obtained in Example 2 (magnification: 800);

[0066] Figure 11 is the XRD pattern of the α-AlF3 product obtained in Example 3;

[0067] Figure 12 is the SEM image (magnification: 800) of the α-AlF3 product obtained in Example 3.

[0068] Legend: 1, machine body; 2, front machine door; 3, upper machine door; 4, chamber; 5, reaction container; 6, condensation reflux atomizer; 7, communication port; 8, display screen; 9, control panel; 10, gas cylinder; 11, external gas inlet port; 12, condenser inlet; 13, reflux pool outlet; 14, reflux pool; 15, condenser water inlet; 16, condenser water outlet; 17, condensation tube; 18, circulation tube; 19, sealing ring; 20, atomization generator; 21, carrier liquid inlet; 22, carrier gas inlet; 23, reactor sealing ring; 24, fixing ring; 25, chamber shell; 26, cavity layer; 27, reaction container outer wall; 28, reaction container inner wall; 29, external port; 30, temperature sensor; 31, pressure sensor; 32, base; 33, screw 1; 34, clamping piece 1; 35, additional layer; 36, inner clamping layer; 37, clamping piece 2; 38, screw 2; 39, screw 3; 40, clamping piece 3; 41, clamping piece 4; 42, screw 4; 43, 46, 49, magnetic control device; 44, 47, 50, diode; 45, refrigerator; 48, transformer; 51, fan; 52, atomizer nozzle; 53, capillary tube. DETAILED DESCRIPTION

[0069] The method for digesting and separating aluminum fluoride according to the present application comprises: placing a catalyst with an alumina carrier loaded with metal elements into a reaction container of the agglomerated digestion device, adding hydrochloric acid and / or nitric acid, setting a digestion program, introducing inert gas for pre-pressurization, performing primary digestion, and simultaneously starting the condensation reflux atomizer; after the program ends, adding hydrofluoric acid, setting a digestion program, and performing secondary digestion; after the digestion is completed, entering a cooling and crystallization program, performing cooling and crystallization, and separating to obtain a clear sample solution and a solid, drying and roasting the solid to obtain aluminum fluoride crystals, and using the liquid for detection of the content of metal elements.

[0070] Please refer to Figure 1 , the agglomerated digestion device comprises: a machine body 1, a reaction container 5, and a condensation reflux atomizer 6.

[0071] Please refer to Figure 2The condensation reflux atomizer 6 comprises a condenser inlet 12, a reflux outlet 13, a reflux pool 14, a condensation tube 17, an atomizer generator 20, a condenser water inlet 15, a condenser water outlet 16, the lower end of the condensation tube 17 communicates with the reflux pool 14, and the side of the reflux pool 14 communicates with the atomizer generator 20 through a sealing ring 19. The bottom of the condensation reflux atomizer 6 is provided with a condenser lower outlet which communicates with the reaction container 5.

[0072] The atomizer generator 20 is a glass concentric atomizer, the center of which is a capillary tube 53, the capillary tube 53 is parallel to the gas flow of the carrier gas, the carrier gas is introduced through the external gas inlet port 11 on one side of the machine body 1, the gas flow rapidly passes through the end of the capillary tube 53, meets and shears the carrier liquid in the atomizer generator 20 at the atomizer nozzle 52, forms tiny droplets, the tiny droplets are sprayed out with the carrier gas, condensed into condensed liquid through the condensation tube 17, and the condensed liquid droplets flow back into the reflux pool 14 and then into the reaction container 5; the upper part of the reaction container 5 is provided with an external port which communicates with an external inert gas.

[0073] Further, the metal element includes at least one of nickel, cobalt, molybdenum, platinum, palladium, lead, iridium, and ruthenium.

[0074] Further, the content of the aluminum oxide in the catalyst is 10wt%-98wt%, the particle size of the catalyst after grinding is less than 74μm, so as to obtain the best reaction effect; the catalyst is dried at 105℃-120℃ for 100min-150min, cooled, and then placed in the reaction container of the agglomeration digestion device.

[0075] Further, the atomizer generator 20 uses at least one of nitrogen, helium and argon as the carrier gas, the flow rate is 0.05-1.0L / min, and the pressure is 0.1-0.5Mpa; the carrier liquid is a dilute acid solution; the dilute acid solution is selected from hydrochloric acid and / or nitric acid, the mass concentration of the hydrochloric acid and / or nitric acid is 0.5-5.0%, and the flow rate of the carrier liquid is 0.1-2.5mL / min.

[0076] Further, the inert gas is at least one of nitrogen, helium and argon, the flow rate is 0.5-2.0L / min, and the pressure is 0.5-5.0Mpa.

[0077] Further, the hydrochloric acid and / or nitric acid is added in a proportion of 5.0mL-10.0mL acid per 1.0g catalyst, the catalyst is added in an amount of 1.0g-50.0g, the mass concentration of the hydrochloric acid is 10%-37%, the mass concentration of the nitric acid is 40%-68%, and when the hydrochloric acid and the nitric acid are added at the same time, the proportion of the hydrochloric acid to the nitric acid is 1:1-4:1. The temperature of one-time digestion is 120℃-200℃, the pressure is less than 5.0Mpa, and the time is 30min-120min.

[0078] Further, the hydrogen fluoride is added in the proportion of 5.0 mL-10.0 mL hydrogen fluoride per 1.0 g catalyst, the catalyst is added in the amount of 1.0 g-50.0 g, the mass concentration of the hydrogen fluoride is 20%-40%, the temperature of the secondary digestion is 80°C-180°C, the pressure is less than 5.0 Mpa, and the time is 30 min-120 min; the temperature of the crystallization is 15°C-25°C, and the time is 120 min-240 min.

[0079] Further, the drying temperature is 105°C-120°C, the calcination temperature is 450°C-600°C, and the time is 100 min-200 min; the aluminum fluoride crystal is an α crystal of AlF3, the specific surface area is greater than 40 m 2 / g, and the pore size is greater than 50 angstroms.

[0080] Further, referring to Figure 1 , the body 1 comprises a chamber 4, a front door 2, an upper door 3, a display screen 8, a control panel 9, a base 32, a microwave generating system, the chamber 4 is located inside the body 1 and is opened or closed by the front door 2, the upper door 3 is located on the top of the body 1, the display screen 8 and the control panel 9 are located on the top surface or one side surface of the body 1, the microwave generating system is connected to the chamber 4, and the base 32 is not a rotating disc type but a base plate fixed to the bottom surface of the chamber 4; a reaction container 5 is placed on the base 32 of the chamber 4.

[0081] The chamber 4 is a polyhedron, the left and right surfaces and the front and back surfaces are symmetrical respectively or all are symmetrical, or the diagonal surfaces are symmetrical, and the upper and lower surfaces are symmetrical, and is composed of at least 8 inner surfaces to realize the concentrated radiation of microwaves in the chamber.

[0082] Further, the carrier gas in the atomization generator 20 is an inert gas, at least one of nitrogen, helium and argon, the flow rate is 0.05-1.0 L / min, and the pressure is 0.1-0.5 Mpa; the carrier liquid is a dilute acid solution, the dilute acid solution is hydrochloric acid and / or nitric acid, the mass concentration of the hydrochloric acid and / or nitric acid is 0.5-5.0%, and the flow rate of the carrier liquid is 0.1-2.5 mL / min.

[0083] Further, the chamber 4 is a closed rectangular industrial resonant cavity.

[0084] Further, the volume of the chamber 4 is designed according to the volume of the reaction container, the material is all stainless steel or polytetrafluoroethylene, and is provided with a plurality of corrosion-resistant coating layers; the polytetrafluoroethylene can resist acid, alkali, organic solvent and other corrosion.

[0085] Further, the chamber 4 is provided with an exhaust system and a cooling system, is equipped with a high-power exhaust system, and various reactions can be continuously carried out for a long time in a ventilated, safe and easily observed environment. A centrifugal fan is installed in the chamber, and the exhaust capacity is not less than 1.0 m 3 / min; the chamber can also be equipped with air cooling function, continuously cooling the reaction vessel, and real-time display of temperature and pressure.

[0086] Further, the front door 2 and the upper door 3 are equipped with double or triple independent interlocking sensor equipment, power cut when opening, and the microwave generating system cannot work when the door is not closed.

[0087] Further, the front door 2 is provided with an observation window, and the mesh of the metal grid or wire mesh in the observation window is 0.02-0.2mm, effectively preventing microwave leakage.

[0088] Further, the body 1 can be designed as one or more modules, not limited to Figure 1 the two modules shown, and the reaction conditions of each module can be controlled by program.

[0089] Further, the shape of the reaction vessel 5 is selected from one of a spherical type, a cylindrical type, a cubic type, and a polyhedral type, and the upper part of the reaction vessel has an external interface connected to an external inert gas.

[0090] Further, the material of the reaction vessel 5 is one of trifluoroethylene (PTFE), perfluoroalkoxy vinyl (PFA), modified polytetrafluoroethylene (TFM), and quartz, which can penetrate and propagate microwaves, so these materials do not absorb or rarely absorb microwave energy, and by penetrating, the ability of the sample inside the reaction vessel to absorb microwaves is enhanced.

[0091] Further, the outer wall 27 of the reaction vessel wall 5 is a waveguide layer that helps microwave penetration and good temperature conduction, and its material should be a non-polar molecular substance. Due to the accelerated transformation of microwave frequency, molecules will collide and rub against each other, and the reaction will be intense. To improve the safety of operation, materials with small deformation, small permeability, good high-temperature and high-pressure recovery, and high surface finish under high temperature and high pressure can be selected, such as polyether ether ketone (PEEK), which is a special engineering plastic with excellent properties such as high temperature resistance, self-lubrication, easy processing, and high mechanical strength. The waveguide layer uses PEEK fiber containing more than 10% carbon fiber or more than 10% glass fiber, but is not limited to this. It can also be other new materials with high temperature resistance and high mechanical strength, but is not limited to this.

[0092] Further, the volume of the reaction vessel 5 is 200mL-2000mL.

[0093] Further, the working temperature of the reaction vessel 5 is 0-350℃, and at the highest temperature, the internal pressure can reach 5.0Mpa.

[0094] Further, the reaction vessel is introduced with reagents, which are acid, base or other reagents required for digestion, the acid is at least one of hydrochloric acid, nitric acid, phosphoric acid, hydrofluoric acid, hydrobromic acid, hydroiodic acid, sulfuric acid, perchloric acid, boric acid, oxalic acid, tartaric acid, citric acid, the base is at least one of ammonia, sodium hydroxide, and the other reagents required for digestion is hydrogen peroxide.

[0095] Further, the chamber 4 is provided with an optical fiber temperature sensor, and the chamber 4 is controlled by optical fiber, which is not interfered by the microwave field, has high measurement accuracy and good safety. The temperature control range is 0-350℃, and the temperature control accuracy is ±0.5℃.

[0096] Further, referring to Figure 5 , the internal components between the chamber 4 and the body 1 are magnetic control devices 43, 46, 49, diodes 44, 47, 50, refrigerators 45, transformers 48 and fans 51.

[0097] Further, the microwave frequency of the microwave source of the microwave generating system is 2450MHz, and the microwave output power is 0-1600W, which is automatically and continuously adjustable; the microwave of the microwave generating system is non-pulsed continuous automatic frequency control, has long service life and good uniformity of emitted electromagnetic waves.

[0098] Further, the control system adopts a high-precision temperature and pressure control system, and the operator can observe the data and curve of temperature and pressure changes through the control panel to understand the machine operation, monitor the temperature and pressure abnormalities in real time, and ensure safety. The pressure control range is 0-5.0MPa, the pressure control accuracy is 0.01MPa, the overpressure can be automatically adjusted and the microwave emission is stopped, and automatic alarm is provided.

[0099] Further, the refrigerator 45 is a semiconductor refrigerator, which is used for cooling the inside of the chamber, and the working temperature is 0-25℃, and the control temperature is 15-20℃.

[0100] Further, the body 1 is provided with a heat dissipation net and an air outlet on the side.

[0101] Referring to Figure 3The reaction container 5 is placed in the chamber 4, placed on the base 32, connected with the condenser outlet through the fixing ring 24, and fixed by the screws (33, 38, 39, 42); the condensation atomization system is refrigerated by the refrigerator 46, the carrier gas enters the condensation atomization system through the carrier gas inlet 23, the residual phase in the condensation tube is condensed, and the condensed liquid drops flow into the reaction container 5; the working of the whole gathering digestion device is controlled through the control panel 9, the display screen 8 displays all programs in real time, the device is started, the front door 2 and the upper door 3 are automatically locked and cannot be manually opened; the transformer 48 supplies the diodes (44, 47, 50) with work, the diodes are connected with the magnetrons (43, 46, 49), microwaves are sent into the chamber 4 through the cavity layer 26, the microwave gathering is formed in the chamber 4, and the microwave gathering acts on the reaction container 5; the temperature sensor 30 and the pressure sensor 31 in the chamber 4 monitor the temperature and pressure changes in the chamber 4 in real time; the volatile gas leaked in the chamber 4 is discharged through the fan 51, the fan 51 is connected with the exhaust port at the back of the machine body 1, and the residual heat in the chamber 4 is dissipated through the heat dissipation network at the side of the machine body 1.

[0102] The method for digesting and separating aluminum fluoride by the program is specifically as follows: before the reaction, the sample is added into the reaction container 5, the reaction container 5 is placed in the chamber 4 and fixed, the condensation reflux atomizer is connected, and the condensation reflux atomizer is started at the same time. The acid reagent required for the digestion reaction is introduced through the reagent adding port of the condensation reflux atomizer. In the sample digestion process, especially in the digestion of organic samples, instantaneous reaction may be violent, leading to element volatilization. Therefore, the condensation reflux atomizer should be started in advance before the digestion reagent is introduced, so as to prevent instantaneous volatilization and avoid element loss. The control panel 9 is opened, the reaction temperature, time and pressure are set, the parameters are set, the program is started, the digestion device starts to work, the carrier gas is started and introduced, the atomization generator works, and the volatile phase remaining in the condensation tube wall is atomized into extremely fine mist droplets by the atomization generator, which returns to the reaction container 5 under the condensation action.

[0103] The following examples are only selected to further illustrate the present application, but should not be limited in practical application.

[0104] Example 1:

[0105] The atomization generator 20 uses nitrogen as the carrier gas, the flow rate is 0.05 L / min, and the pressure is 0.1 Mpa; the carrier liquid is dilute hydrochloric acid, the mass concentration is 0.5%, and the flow rate is 0.1 mL / min.

[0106] The inert gas connected with the reaction container 5 is nitrogen, the flow rate is 0.5 L / min, and the pressure is 0.5 Mpa.

[0107] The cavity structure is a polyhedron, which is symmetrical in left-right, front-back, diagonal, and up-down directions, and is composed of 8 inner surfaces.

[0108] The chamber 4 is a closed rectangular industrial resonant cavity. The chamber 4 is made of all stainless steel and is provided with multiple layers of corrosion-resistant coating. The chamber 4 is provided with an exhaust system and a cooling system, and a centrifugal fan is installed in the chamber. The exhaust capacity is 5.0 m 3 / min; the chamber is also provided with air cooling function to continuously cool the reaction vessel and display the temperature and pressure in real time.

[0109] The front door 2 is provided with an observation window, and the mesh of the metal grid or wire mesh in the observation window is 0.1 mm, which effectively prevents microwave leakage.

[0110] The body 1 can be designed as a two-cavity chamber, and each cavity can be controlled by a program to control the reaction conditions.

[0111] The shape of the reaction vessel 5 is spherical, and the upper part of the reaction vessel is provided with an external interface connected with an external inert gas.

[0112] The material of the reaction vessel 5 is polytetrafluoroethylene (PTFE), which can penetrate and propagate microwaves.

[0113] The outer wall 27 of the reaction vessel 5 is a waveguide layer, which helps the penetration of microwaves and good temperature conduction. The material of the outer wall 27 is a non-polar molecular substance, which is made of PEEK fiber containing 25% carbon fiber.

[0114] The volume of the reaction vessel 5 is 200 mL. The working temperature of the reaction vessel 5 is 0-350℃, and the internal pressure can reach 5.0 Mpa at the highest temperature.

[0115] The microwave frequency of the microwave source of the microwave generating system is 2450 MHz, and the microwave output power is 1500 W.

[0116] (1) Standard recovery comparison test

[0117] Using the method, 1.0 g of the Ni element loaded alumina-based catalyst sample (accurate to 0.001 g) is accurately weighed, and three parallel samples are weighed, two of which are added with Ni standard material 10.0 mg / L, 15.0 mg / L and 20.0 mg / L (taken from 1000 mg / L of Ni standard solution, commercially available inorganic standard solution), and the set digestion program is shown in Table 1-1, 5.0 mL of hydrochloric acid 10% (commercially available, high purity) is added, the temperature is 120°C, the pressure is 0.5 Mpa, and the time is 30 min, one-time program digestion is carried out, 5.0 mL of hydrofluoric acid 25% (commercially available, high purity) is added, the temperature is 80°C, the pressure is 0.5 Mpa, and the time is 30 min, two-time program digestion is carried out, after digestion is completed, the cooling crystallization program is entered, cooling crystallization is carried out, the crystallization temperature is 15°C, and the time is 120 min. The clear sample solution to be measured and the solid are separated, the solid is dried and calcined, the drying temperature is 105°C, the calcination temperature is 450°C, and the time is 100 min, the aluminum fluoride crystal is obtained, the liquid is separated and transferred to a 100 mL volumetric flask for constant volume, and is used for the detection of the content of the Ni element. The serial concentration standard solution for the determination of the Ni element is 0 mg / L (blank), 5.0 mg / L, 10.0 mg / L, 15.0 mg / L, 20.0 mg / L and 25.0 mg / L in turn.

[0118] Table 1-1 Digestion program setting

[0119]

[0120] The comparative example uses a direct wet digestion method to process the sample, and then uses a matrix matching method and an internal standard method to process and measure the sample after processing.

[0121] The direct wet digestion sample processing method accurately weighs 1.0 g of the Ni element loaded alumina-based catalyst sample (accurate to 0.001 g), and three parallel samples are weighed and placed in a quartz crucible, 5.0 mL of hydrochloric acid 10% (commercially available, high purity) is added, and the sample is digested on a hot plate at 120°C for 30 min, then 5.0 mL of hydrofluoric acid 25% (commercially available, high purity) is added, and the sample is continuously digested on a hot plate at 80°C for 30 min, after digestion is completed, the digestion liquid is transferred to a 100 mL volumetric flask for constant volume, and is used for the detection of the content of the Ni element.

[0122] The matrix matching method is used for the determination of the Ni standard solution, which should contain the matching concentration of Al element in the sample. After the direct wet digestion treatment, the sample contains a large amount of Al element with a concentration of about 43wt%, so the Ni standard solution is prepared to contain the matrix with a concentration of 43wt% Al element for instrument detection. The determination of Ni element series concentration standard solution is 0mg / L (blank), 5.0mg / L, 10.0mg / L, 15.0mg / L, 20.0mg / L and 25.0mg / L, and the concentration of Al is 43%. The concentration value of the measured sample should fall within the linear range of the standard working curve.

[0123] The internal standard method is used for the determination of the Ni standard solution, which should introduce internal standard elements to eliminate the interference of Al element. In this experiment, the internal standard element is Sn, so the Ni standard solution is prepared to contain Sn internal standard solution for instrument detection. The determination of Ni element series concentration standard solution is 0mg / L (blank), 5.0mg / L, 10.0mg / L, 15.0mg / L, 20.0mg / L and 25.0mg / L, and the concentration of internal standard Sn is 10.0mg / kg. The concentration value of the measured sample should fall within the linear range of the standard working curve.

[0124] Generally, the amount of standard addition should not be too large, and it is generally appropriate to be 0.5-2.0 times the content of the measured substance. Under certain working conditions of inductively coupled plasma emission spectrometer (American Platinum Elmer Company, model 5300DV), the samples treated by the present digestion method and direct wet digestion method were determined, and the determination of the present method, matrix matching method and internal standard method was carried out. The concentration values of Ni element in the sample solution before and after standard addition were determined by three methods, and the recovery rate was calculated. The results are shown in Tables 1-2.

[0125] Tables 1-2 Recovery test results

[0126]

[0127] From the results of Table 1-2, it can be seen that the results determined by the matrix matching method and the internal standard method after the direct wet digestion treatment before the addition of the standard sample are lower than the results determined by the present method; among the results after the addition of the standard sample of the three different concentrations, the recovery rate of the Ni element of the present method is 101.50%, 100.60% and 98.80%, the results are all above 95%, and the recovery rate is higher than the results determined by the matrix matching method and the internal standard method after the direct wet digestion treatment. Since the content of the Al element in the catalyst is relatively high, it has a certain interference on the determination of the Ni element, the matrix matching method and the internal standard method can correct the determination of the Ni element to a certain extent, but compared with the results determined after the treatment by the present program digestion device, the accuracy is reduced to a certain extent. Therefore, after the treatment by the present program digestion device, the Al matrix in the sample is effectively removed, and the accuracy of the results is higher.

[0128] (2) Comparative test of the influence of the Al matrix and the removal of the Al matrix on the determination of the Ni element

[0129] The sample treatment method of the Al matrix is that the step of adding HF acid for secondary digestion is not performed on the Ni element loaded alumina-based catalyst sample, and the other operation steps are unchanged, and the influence of the Al matrix and the removal of the Al matrix on the determination of the Ni element is investigated. By adding HF, the AlF3precipitate is obtained in the sample solution, the Al matrix is removed in the form of the AlF3precipitate, and the sample solution in which the Al matrix is removed (the content of Al is about 30 μg / mL) is obtained; in addition, the sample solution containing the Al matrix (the content of Al is about 43 wt%) is obtained by performing the operation same as the present method except that the HF is not added. The sample solutions obtained by the two pretreatments are determined, and the results are shown in Table 1-3.

[0130] Table 1-3 Determination results of the Ni element in the sample solution with the Al matrix and the removal of the Al matrix

[0131]

[0132] From the results of Table 1-3, it can be seen that the determination results of the Ni element in the sample solution in which the Al matrix is not removed are obviously lower than the sample solution in which the Al matrix is removed by using the present program digestion device, which indicates that the removal of the Al matrix by the secondary digestion of HF in the present method can ensure the accuracy of the determination results and eliminate the interference of the matrix on the element determination.

[0133] (3) X-ray diffraction analysis test

[0134] The substance obtained by repeatedly washing and drying the filter after the treatment of the above-mentioned catalyst sample loaded with the Ni element by the program digestion is scanned by X-ray diffraction spectrum, the X-ray diffractometer (Maven Panalytical Company, Netherlands, model sharp image) is used, the Cu target is used, the tube current is 40 mA, the tube voltage is 45 KV, the continuous scanning 2θ angle is 5°-90°, the step is 0.01°, and the results are shown in Figure 1.Figure 7 The spectrum was analyzed by Highscore software and PDF database, and the result was AlF3 (PDF 04-023-5575) α-type crystal.

[0135] (4) Scanning electron microscope analysis test

[0136] The substance obtained by repeatedly washing and drying the filtrate after treating the catalyst sample loaded with Ni element by programmed digestion was analyzed by scanning electron microscope (Japan Electronics Corporation, model JSM-6360LA), with an accelerating voltage of 30 kV, a resolution of 0.3 nm, a vacuum degree of 270 Pa, and a scanning electron microscope analysis result of 800 times as shown in FIG. 4. Figure 8 As can be seen from FIG. 4, the crystal is obviously cubic, verifying that the AlF3 α-type crystal is cubic. Figure 8

[0137] (5) Specific surface area and pore volume analysis test

[0138] The substance obtained by repeatedly washing and drying the filtrate after treating the catalyst sample loaded with Ni element by programmed digestion was analyzed by specific surface area and pore volume (American Micromeritics Corporation, model TriStar TM3000), and the specific surface area and pore volume determination result was 41.6187 m 2 / g, 12.81 nm.

[0139] Example 2:

[0140] The atomization generator 20 uses helium as the carrier gas, with a flow rate of 1.0 L / min and a pressure of 0.5 MPa; and dilute nitric acid with a mass concentration of 5% as the carrier liquid, with a flow rate of 2.5 mL / min.

[0141] The inert gas connected to the reaction container 5 is nitrogen, with a flow rate of 2.0 L / min and a pressure of 5.0 MPa.

[0142] The cavity structure is a polyhedron, which is symmetric on the left and right, front and back, or diagonally, and symmetric on the upper and lower surfaces, composed of 8 inner surfaces.

[0143] The chamber 4 is a closed rectangular industrial resonant cavity. The chamber 4 is made of all stainless steel and is provided with multiple layers of corrosion-resistant coating. The chamber 4 is provided with an exhaust system and a cooling system, and a centrifugal fan is installed in the chamber, with an exhaust capacity of 5.0 m 3 / min; the chamber is also provided with air cooling function, which continuously cools the reaction container and displays the temperature and pressure in real time.

[0144] The front door 2 is provided with an observation window, and the mesh of the metal grid or wire mesh of the observation window is 0.1 mm, effectively preventing microwave leakage.

[0145] ​The machine body 1 is designed as two module chambers, and each chamber can be controlled by program to react under different conditions.

[0146] The shape of the reaction container 5 is cylindrical, and the upper part of the reaction container is connected with an external interface for connecting with external inert gas.

[0147] The material of the reaction container 5 is PTFE, which can be penetrated and propagated by microwaves.

[0148] The outer wall 27 of the reaction container 5 is a waveguide layer, which is helpful for the penetration of microwaves and good temperature conduction, and the material of the outer wall 27 is a non-polar molecular substance, which is made of PEEK fiber containing 25% carbon fiber.

[0149] The volume of the reaction container 5 is 2000 mL. The working temperature of the reaction container 5 is 0-350℃, and the internal pressure can reach 5.0 Mpa at the highest temperature.

[0150] The microwave frequency of the microwave source of the microwave generating system is 2450 MHz, and the microwave output power is 1400 W.

[0151] (1) Standard recovery comparison test

[0152] According to the method, 50.0 g (accurate to 0.001 g) of the Pt element loaded alumina-based catalyst sample is accurately weighed, and three parallel samples are weighed, two of which are added with Pt standard material of 50.0 mg / L, 100.0 mg / L and 200.0 mg / L (taken from 1000 mg / L Pt standard solution, commercially available inorganic standard solution), and the set digestion program is shown in Table 2-1 by using the agglomeration digestion device according to the method. 400.00 mL of hydrochloric acid 10% (commercially available, premium pure) and 100.00 mL of nitric acid 40% (commercially available, premium pure) are added, the mixed acid is mixed, the temperature is 200℃, the pressure is 5.0 Mpa, and the time is 120 min. One-time program digestion is carried out, 500.0 mL of hydrofluoric acid 25% (commercially available, premium pure) is added, the temperature is 180℃, the pressure is 5.0 Mpa, and the time is 120 min. Two-time program digestion is carried out, and after digestion is completed, the cooling crystallization program is entered, and the cooling crystallization is carried out. The crystallization temperature is 25℃, and the time is 240 min. The clear sample solution and the solid are separated, the solid is dried and roasted, the drying temperature is 105℃, the roasting temperature is 450℃, and the time is 100 min. The aluminum fluoride crystal is obtained, the liquid is separated and transferred to a 100 mL volumetric flask for constant volume, and used for the detection of the content of Pt element. The Pt element series concentration standard solution for determination is 0 mg / L (blank), 5.0 mg / L, 10.0 mg / L, 15.0 mg / L, 20.0 mg / L and 25.0 mg / L in turn.

[0153] Table 2-1 Digestion program setting

[0154]

[0155] The comparative example uses a direct wet digestion method to treat the sample, and then uses a matrix matching method and an internal standard method to treat the sample and then determine.

[0156] The direct wet digestion sample treatment method has a limited sample treatment amount, and cannot realize large mass weighing. Generally, the mass should be less than 15.0 g. 10.0 g (accurate to 0.001 g) of the Pt element loaded alumina catalyst sample is accurately weighed, and three parallel samples are weighed and placed in a quartz crucible. 20.0 mL of 10% hydrochloric acid (commercially available, premium grade) and 5.0 mL of 40% nitric acid (commercially available, premium grade) mixed acid are added, and the sample is digested on an electric heating plate at 200°C for 100 min. Then 15.0 mL of 25% hydrofluoric acid (commercially available, premium grade) is added, and the sample is continuously digested on the electric heating plate at 180°C for 60 min. After the digestion is completed, the digestion solution is transferred to a 100 mL volumetric flask for constant volume, and used for Pt element content detection.

[0157] The matrix matching method uses a Pt standard solution containing Al element matching the concentration in the sample. After the direct wet digestion treatment, the aluminum element is not separated and removed, and exists in large amounts in the sample solution, with a concentration of about 45 wt%. Therefore, the Pt standard solution is prepared to contain a matrix of 45 wt% Al element for instrument detection. The Pt element series concentration standard solution for determination is 0 mg / L (blank), 5.0 mg / L, 10.0 mg / L, 15.0 mg / L, 20.0 mg / L and 25.0 mg / L in turn, with Al concentration of 43%. The element concentration value in the measured sample should fall within the linear range of the standard working curve.

[0158] The internal standard method uses a Pt standard solution with an internal standard element introduced for eliminating the interference of Al element. In this experiment, the internal standard element is Cd, so the Pt standard solution is prepared to contain a Cd internal standard solution for instrument detection. The Pt element series concentration standard solution for determination is 0 mg / L (blank), 5.0 mg / L, 10.0 mg / L, 15.0 mg / L, 20.0 mg / L and 25.0 mg / L in turn, with Cd internal standard concentration of 10.0 mg / kg. The element concentration value in the measured sample should fall within the linear range of the standard working curve.

[0159] Generally, the spiking amount should not be too large, and it is appropriate to be 0.5-2.0 times of the content of the measured substance. Under certain working conditions of an inductively coupled plasma emission spectrometer (American Platinum Elmer Company, model 5300DV), the samples treated by the present digestion method and direct wet digestion were determined, and the sample solutions were determined by the present method, matrix matching method and internal standard method. The concentrations of Pt element in the sample solutions before and after spiking were determined, and the recovery rates were calculated. The results are shown in Table 2-2.

[0160] Table 2-2 Recovery rate test results

[0161]

[0162] As can be seen from the results in Table 2-2, the results determined by the matrix matching method and internal standard method after direct wet digestion treatment before spiking are lower than the results determined by the present method. Among the results after spiking of three different concentrations, the recovery rates of Pt element by the present method are 100.50%, 98.30% and 99.60%, all of which are above 95%, and the recovery rates are higher than the results determined by the matrix matching method and internal standard method after direct wet digestion treatment. Since the content of Al element in the catalyst is relatively high, it has a certain interference on the determination of Pt element. Although the matrix matching method and internal standard method can correct the determination of Pt element to a certain extent, the accuracy is reduced compared with the results determined after the sample is treated by the present batch digestion device. Therefore, after the sample is treated by the present batch digestion device, the aluminum matrix in the sample is effectively removed, and the accuracy of the results is higher.

[0163] (2) Comparison test of the influence of Al-containing matrix and removal of Al matrix on the determination of Pt element

[0164] The sample treatment method of Al-containing matrix is that the step of adding HF acid for secondary digestion is not performed on the Pt element-loaded alumina-based catalyst sample, and the other operation steps remain unchanged, so as to investigate the influence of Al-containing matrix and removal of Al matrix on the determination of Pt element. By adding HF, AlF3precipitate is generated in the sample solution, and the Al matrix is removed in the form of AlF3precipitate, so as to obtain a sample solution in which the Al content is about 50 μg / mL. In addition, by adopting the test of the present method except that HF is not added, a sample solution containing Al matrix (the Al content is about 45 wt%) can be obtained. The sample solutions obtained by the two pretreatment methods are determined, and the results are shown in Table 2-3.

[0165] Table 2-3 Determination results of Pt element with Al-containing matrix and removal of Al matrix

[0166]

[0167] From the results of Table 2-3, it can be seen that the determination results of Pt element in the sample solution without removing Al matrix are obviously lower than those of the sample solution with removing Al matrix by using the present agglomerated digestion device, which shows that the removal of Al matrix by HF secondary digestion in the present method can ensure the accuracy of the determination results and eliminate the interference of the matrix on the element determination.

[0168] (3) X-ray diffraction analysis test

[0169] The substance obtained by repeatedly washing and drying the filtrate after the treatment of the above Pt element loaded catalyst sample by the programmed digestion was subjected to X-ray diffraction spectrum scanning using an X-ray diffractometer (Malvern Panalytical, model RIGAKU), Cu target, tube current 40 mA, tube voltage 45 KV, continuous scanning of 2 theta angle at 5°-90°, step 0.01°, as shown in Figure 9 The spectrum was analyzed by Highscore software and PDF database, and the result was AlF3 (PDF 04-023-5575) α type crystal.

[0170] (4) Scanning electron microscope analysis test

[0171] The substance obtained by repeatedly washing and drying the filtrate after the treatment of the above Pt element loaded catalyst sample by the programmed digestion was subjected to scanning electron microscope (JEOL, model JSM-6360LA) analysis at an acceleration voltage of 30 kV, a resolution of 0.3 nm, a vacuum degree of 270 Pa, and a scanning electron microscope analysis result of 2000 times as shown in Figure 10 From Figure 10 it can be seen that the crystal is obviously cubic crystal, which verifies that the AlF3 α type crystal is cubic crystal.

[0172] (5) Specific surface area and pore volume analysis test

[0173] The substance obtained by repeatedly washing and drying the filtrate after the treatment of the above Pt element loaded catalyst sample by the programmed digestion was subjected to specific surface area and pore volume (Micromeritics, model TriStar TM3000) analysis, and the specific surface area and pore volume determination result was 122.8955 m 2 / g, 7.55 nm.

[0174] Example 3:

[0175] The atomization generator 20 uses argon as the carrier gas, the flow rate is 0.1 L / min, and the pressure is 0.2 Mpa; the carrier liquid is dilute nitric acid with a mass concentration of 1.0%, and the flow rate is 0.5 mL / min.

[0176] The inert gas connected to the reaction container 5 is argon, the flow rate is 1.0 L / min, and the pressure is 1.5 Mpa.

[0177] The cavity structure is a polyhedron, with symmetrical surfaces on the left and right, front and back, or diagonal surfaces and vertical surfaces, consisting of 8 inner surfaces.

[0178] Chamber 4 is a sealed rectangular industrial resonant cavity. Chamber 4 is made entirely of stainless steel with a multi-layered anti-corrosion coating. Chamber 4 is equipped with an exhaust system and a cooling system, and a centrifugal fan is installed inside the chamber, with an exhaust volume of 5.0 m³ / h. 3 / min; the chamber is also equipped with an air-cooling function to continuously cool the reaction vessel and display the temperature and pressure in real time.

[0179] The front door 2 is equipped with an observation window. The metal grid or wire mesh of the observation window has a mesh size of 0.1mm, which effectively prevents microwave leakage.

[0180] The body 1 is designed with two chambers, and the reaction conditions of each chamber can be controlled by a program.

[0181] The reaction vessel 5 is cylindrical in shape, and has an external interface at the top for connection with an external inert gas.

[0182] The reaction vessel 5 is made of polytetrafluoroethylene (PTFE), which is permeable to microwaves and allows them to propagate.

[0183] The outer wall 27 of the reaction vessel 5 is a waveguide layer, which helps microwave penetration and good temperature conduction. Its material is a non-polar molecular substance, using PEEK fiber, which contains 25% carbon fiber.

[0184] The volume of reaction vessel 5 is 1000 mL. The operating temperature of reaction vessel 5 is 0–350 °C, and the internal pressure can reach 5.0 MPa at the highest temperature.

[0185] The microwave source of the microwave generator system has a microwave frequency of 2450MHz and a microwave output power of 1400W.

[0186] (1) Spiked Recovery Comparison Test

[0187] The application method is used to accurately weigh 10.0 g (accurate to 0.001 g) of the Pb element loaded alumina-based catalyst sample, and three parallel samples are weighed, two of which are added with Pb standard material 2.0 mg / L, 5.0 mg / L and 10.0 mg / L (taken from 1000 mg / L of Pb standard solution, commercially available inorganic standard solution), and the method of the application is used to apply the agglomeration digestion device, and the digestion program is set as shown in Table 3-1, 20.00 mL of 50% nitric acid (commercially available, high-purity) is added, the temperature is 150°C, the pressure is 1.5 Mpa, and the time is 50 min, one-time program digestion is performed, 20.0 mL of 25% hydrofluoric acid (commercially available, high-purity) is added, the temperature is 150°C, the pressure is 1.5 Mpa, and the time is 75 min, two-time program digestion is performed, and after the digestion is completed, the cooling crystallization program is entered, cooling crystallization is performed, the crystallization temperature is 18°C, and the time is 150 min. The clear sample solution and the solid are separated, the solid is dried and calcined, the drying temperature is 105°C, the calcination temperature is 450°C, and the time is 100 min, the aluminum fluoride crystal is obtained, the liquid is separated and transferred to a 100 mL volumetric flask for constant volume, and is used for the detection of the Pb element content. The Pb element series concentration standard solution for determination is 0 mg / L (blank), 5.0 mg / L, 10.0 mg / L, 15.0 mg / L, 20.0 mg / L and 25.0 mg / L in turn.

[0188] Table 3-1 Digestion program setting

[0189]

[0190] The comparative example uses a direct wet digestion method to process the sample, and then uses a matrix matching method and an internal standard method to process and determine the sample after processing.

[0191] The direct wet digestion sample processing method has a limited sample processing amount and cannot realize large mass weighing, and the mass should generally be less than 15.0 g, 10.0 g (accurate to 0.001 g) of the Pb element loaded alumina-based catalyst sample is accurately weighed, and three parallel samples are weighed and placed in a quartz crucible, 20.0 mL of 50% nitric acid (commercially available, high-purity) is added, and the sample is digested on an electric heating plate at 200°C for 100 min, then 15.0 mL of 25% hydrofluoric acid (commercially available, high-purity) is added, and the sample is continuously digested on the electric heating plate at 180°C for 60 min, after the digestion is completed, the digestion liquid is transferred to a 100 mL volumetric flask for constant volume, and is used for the detection of the Pb element content.

[0192] The matrix matching method requires that the Pb standard solution used in the determination process contain a concentration matching that of Al in the sample. After direct wet digestion, aluminum remains largely present in the sample solution at a concentration of approximately 45 wt%. Therefore, the Pb standard solution is prepared to contain a matrix with a concentration of 45 wt% Al for instrumental detection. The series of Pb standard solutions used for determination are 0 mg / L (blank), 5.0 mg / L, 10.0 mg / L, 15.0 mg / L, 20.0 mg / L, and 25.0 mg / L, containing 43% Al. The elemental concentration in the sample should fall within the linear range of the standard working curve.

[0193] In the internal standard method, the Pb standard solution used in the determination process should introduce an internal standard element to eliminate interference from Al. In this experiment, Cd was chosen as the internal standard element. Therefore, the Pb standard solution was prepared as a standard solution containing Cd internal standard element for instrument detection. The Pb element standard solutions used for determination were 0 mg / L (blank), 5.0 mg / L, 10.0 mg / L, 15.0 mg / L, 20.0 mg / L, and 25.0 mg / L, respectively. The concentration of the internal standard Cd was 10.0 mg / kg. The element concentration value in the sample should fall within the linear range of the standard working curve.

[0194] In general, the amount of spiked material should not be too large, typically 0.5 to 2.0 times the concentration of the analyte. Under specific operating conditions using an inductively coupled plasma atomic emission spectrometer (Platinum Elmer, USA, model 5300DV), samples treated with this digestion method and direct wet digestion were analyzed. The concentrations of Pb in the sample solutions before and after spiking were determined using this method, matrix matching method, and internal standard method. The recovery rates were calculated, and the results are shown in Table 3-2.

[0195] Table 3-2 Results of Recovery Rate Test

[0196]

[0197] From the results of Table 3-2, it can be seen that the results determined by the matrix matching method and the internal standard method after the direct wet digestion treatment before the addition of the standard sample are seriously lower than the results determined by the present method; among the results after the addition of the three groups of different concentrations of the standard sample, the recovery rates of the Pb element by the present method are 95.50%, 98.20% and 97.70%, all of which are above 95%, and the recovery rates are much higher than the results determined by the matrix matching method and the internal standard method after the direct wet digestion treatment. Since the content of the Al element in the catalyst is relatively high, it seriously interferes with the determination of the Pb element, and the lead element volatilizes greatly during the digestion process, resulting in that the determination results after the direct wet digestion treatment are low. Although the matrix matching method and the internal standard method theoretically play a certain correction role in the determination of the Pb element, the accuracy in the actual determination is difficult to meet. Therefore, after the sample is treated by the present collective digestion device program, the aluminum matrix in the sample is effectively removed, and the accuracy of the results is ensured.

[0198] (2) Comparison test of the influence of Al-containing matrix and removal of aluminum matrix on the determination of Pb element

[0199] The sample treatment method containing the Al matrix is a step of not performing the secondary digestion of HF acid on the alumina-based catalyst sample loaded with the Pb element, and the other operation steps are unchanged, and the influence of the Al-containing matrix and the removal of the Al matrix on the determination of the Pb element is investigated. By adding the HF, the AlF3 precipitate appears in the sample solution, the Al matrix is removed in the form of the AlF3 precipitate, and the sample solution from which the Al matrix is removed (the Al content is about 44 μg / mL) is obtained; in addition, the sample solution containing the aluminum matrix (the Al content is about 45 wt%) is obtained by adopting the test of not adding the HF and other operations same as the present method. The two sample solutions obtained by the pretreatment are determined, and the results are shown in Table 3-3.

[0200] Table 3-3 Determination results of the Pb element in the Al-containing matrix and the removal of the Al matrix

[0201]

[0202] From the results of Table 3-3, it can be seen that the determination results of the Pb element in the sample solution in which the Al matrix is not removed are obviously lower than those in which the Al matrix is removed by using the present collective digestion device, and the high content of the Al matrix greatly interferes with the determination of the Pb element. In the present method, the Al matrix is removed by the secondary digestion of the HF, which can ensure the accuracy of the determination results and eliminate the interference of the matrix on the element determination.

[0203] (3) X-ray diffraction analysis test

[0204] The material obtained by repeatedly washing and drying the filtrate after treating the catalyst sample loaded with Pb element by the procedure described above was subjected to X-ray diffraction spectrum scanning using an X-ray diffractometer (Malvern Panalytical, model Sharp XRD), Cu target, tube current 40 mA, tube voltage 45 KV, continuous scanning 2 theta angle 5°-90°, step 0.01°, as shown in Figure 11 The spectrum was analyzed by Highscore software and PDF database, and the result was AlF3 (PDF 04-023-5575) alpha crystal.

[0205] (4) Scanning electron microscope analysis test

[0206] The material obtained by repeatedly washing and drying the filtrate after treating the catalyst sample loaded with Pb element by the procedure described above was subjected to scanning electron microscope (JEOL, model JSM-6360LA) analysis, acceleration voltage 30 kV, 0.3 nm resolution, vacuum degree 270 Pa, 2000 times scanning electron microscope analysis result as shown in Figure 12 It can be seen that the crystal is obviously cubic crystal, which verifies that the AlF3 alpha crystal is cubic crystal. Figure 12

[0207] (5) Specific surface area and pore volume analysis test

[0208] The material obtained by repeatedly washing and drying the filtrate after treating the catalyst sample loaded with Pb element by the procedure described above was subjected to specific surface area and pore volume (Micromeritics, model TriStar TM3000) analysis, and the specific surface area and pore volume determination result was 168.8455 m 2 / g, 5.04 nm.

[0209] Example 4:

[0210] The atomization generator 20 uses argon as the carrier gas, the flow rate is 0.3 L / min, and the pressure is 0.3 MPa; the carrier liquid is dilute nitric acid with a mass concentration of 4.0%, and the flow rate is 1.7 mL / min.

[0211] The inert gas connected to the reaction container 5 is argon, the flow rate is 1.5 L / min, and the pressure is 3.5 MPa.

[0212] The cavity structure is a polyhedron, which is symmetric on the left and right, front and back, or diagonal, and symmetric on the upper and lower surfaces, composed of 8 inner surfaces.

[0213] The chamber 4 is a closed rectangular industrial resonant cavity. The chamber 4 is made of all stainless steel and is provided with multiple layers of corrosion-resistant coating. The chamber 4 is provided with an exhaust system and a cooling system, and a centrifugal fan is installed in the chamber, with an exhaust capacity of 5.0 m 3 ​The chamber is also equipped with air cooling function to continuously cool the reaction vessel and display the temperature and pressure in real time.

[0214] The front door 2 is provided with an observation window, the mesh of the metal grid or wire mesh of the observation window is 0.1mm, which effectively prevents microwave leakage.

[0215] The body 1 is designed as a two-module chamber, and each chamber can be controlled by program to control the reaction conditions.

[0216] The shape of the reaction vessel 5 is cylindrical, and the upper part of the reaction vessel is provided with an external interface connected with external inert gas.

[0217] The material of the reaction vessel 5 is PTFE, which can penetrate and propagate microwaves.

[0218] The outer wall 27 of the reaction vessel 5 is a waveguide layer, which helps the penetration of microwaves and good temperature conduction, and the material is a non-polar molecular substance, which adopts PEEK fiber containing 25% carbon fiber.

[0219] The volume of the reaction vessel 5 is 450mL. The working temperature of the reaction vessel 5 is 0-350℃, and the internal pressure can reach 5.0Mpa at the highest temperature.

[0220] The microwave frequency of the microwave source of the microwave generating system is 2450MHz, and the microwave output power is 1400W.

[0221] (1) Standard addition recovery comparison test

[0222] The application method is used to accurately weigh 20.0 g (accurate to 0.001 g) of the Co element loaded alumina-based catalyst sample, and three parallel samples are weighed, two of which are added with Co standard substances of 20.0 mg / L, 40.0 mg / L and 60.0 mg / L (taken from a Co standard solution of 1000 mg / L, commercially available inorganic standard solution), and the set digestion program is shown in Table 4-1, 30.00 mL of hydrochloric acid of 28% (commercially available, high-purity) and 30.00 mL of nitric acid of 52% (commercially available, high-purity) are added, the mixed acid is mixed, the temperature is 170°C, the pressure is 3.5 Mpa, and the time is 80 min for one-time program digestion; 30.0 mL of hydrofluoric acid of 30% (commercially available, high-purity) is added, the temperature is 160°C, the pressure is 3.5 Mpa, and the time is 100 min for two-time program digestion, and after the digestion is completed, the cooling crystallization program is entered for cooling crystallization, the crystallization temperature is 22°C, and the time is 160 min. The clear sample solution and the solid are separated, the solid is dried and roasted, the drying temperature is 105°C, the roasting temperature is 450°C, and the time is 100 min to obtain aluminum fluoride crystals, the liquid is separated and transferred to a 100 mL volumetric flask for constant volume for Co element content detection. The Co element series concentration standard solution for determination is 0 mg / L (blank), 5.0 mg / L, 10.0 mg / L, 15.0 mg / L, 20.0 mg / L and 25.0 mg / L in turn.

[0223] Table 4-1 Digestion program setting

[0224]

[0225] The comparative example uses a direct wet digestion method to process the sample, and then uses a matrix matching method and an internal standard method to process and determine the sample after processing.

[0226] The direct wet digestion sample processing method has a limited sample processing amount and cannot realize large mass weighing, and the mass should generally be less than 15.0 g, 10.0 g (accurate to 0.001 g) of the Co element loaded alumina-based catalyst sample is accurately weighed, and three parallel samples are weighed and placed in a quartz crucible, 10.0 mL of hydrochloric acid of 28% (commercially available, high-purity) and 10.0 mL of nitric acid of 52% (commercially available, high-purity) are added to mixed acid, and the acid is digested on an electric heating plate at 170°C for 100 min, then 20.0 mL of hydrofluoric acid of 30% (commercially available, high-purity) is added, and the acid is continuously digested on the electric heating plate at 160°C for 100 min, and after the digestion is completed, the digestion liquid is transferred to a 100 mL volumetric flask for constant volume for Co element content detection.

[0227] The Co standard solution used in the determination process should contain Al element matching the concentration in the sample. The sample treated by direct wet digestion contains a large amount of Al element in the sample solution without separation and removal, and the concentration is about 45wt%. Therefore, the Co standard solution is prepared to contain Al element with a concentration of 45wt% for instrument detection. The Co element series concentration standard solution for determination is 0mg / L (blank), 5.0mg / L, 10.0mg / L, 15.0mg / L, 20.0mg / L and 25.0mg / L in turn, and the Al concentration is 45wt%. The element concentration value in the measured sample should fall within the linear range of the standard working curve.

[0228] The Co standard solution used in the determination process should contain Al element matching the concentration in the sample. The sample treated by direct wet digestion contains a large amount of Al element in the sample solution without separation and removal, and the concentration is about 45wt%. Therefore, the Co standard solution is prepared to contain Al element with a concentration of 45wt% for instrument detection. The Co element series concentration standard solution for determination is 0mg / L (blank), 5.0mg / L, 10.0mg / L, 15.0mg / L, 20.0mg / L and 25.0mg / L in turn, and the Al concentration is 45wt%. The element concentration value in the measured sample should fall within the linear range of the standard working curve.

[0229] Generally, the amount of the added standard should not be too large, and it is appropriate to be 0.5-2.0 times the content of the measured substance. Under certain working conditions of the inductively coupled plasma emission spectrometer (American Platinum Elmer Company, model 5300DV), the samples treated by the present digestion method and direct wet digestion method were determined, and the Co element concentration values in the sample solutions before and after the addition of the standard were determined by the present method, matrix matching method and internal standard method. The recovery rate was calculated, and the results are shown in Table 4-2.

[0230] Table 4-2 Recovery rate test results

[0231]

[0232] From the results of Table 4-2, it can be seen that the results determined by the matrix matching method and the internal standard method after the direct wet digestion treatment before spiking are seriously lower than the results determined by the present method; among the results after spiking of the three groups of different concentrations, the recovery rates of Co element by the present method are 100.20%, 103.40% and 99.70%, all of which are above 95%, and the recovery rates are higher than the results determined by the matrix matching method and the internal standard method after the direct wet digestion treatment. Since the content of Al element in the catalyst is relatively high, it has certain interference to the determination of Co element. Although the matrix matching method and the internal standard method can theoretically correct the determination of Co element to a certain extent, the accuracy in actual determination is difficult to meet. Therefore, after the program digestion treatment by the present cluster digestion device, the aluminum matrix in the sample is effectively removed, ensuring the accuracy of the results.

[0233] (2) Comparison test of influence of Al-containing matrix and removal of aluminum matrix on determination of Co element

[0234] The sample treatment method containing Al matrix is a step of not performing secondary digestion with HF acid for the Co element loaded alumina-based catalyst sample, and other operation steps remain unchanged, to investigate the influence of Al-containing matrix and removal of Al matrix on the determination of Co element. By adding HF, AlF3precipitate appears in the sample solution, and the Al matrix is removed in the form of AlF3precipitate, to obtain a sample solution without Al matrix (Al content is about 38 μg / mL); in addition, by adopting the test of not adding HF and other operations same as the present method, a sample solution containing Al matrix (Al content is about 45 wt%) can be obtained. The sample solutions obtained by the two pretreatments are determined, and the results are shown in Table 4-3.

[0235] Table 4-3 Determination results of Co element with Al-containing matrix and removal of Al matrix

[0236]

[0237] From the results of Table 4-3, it can be seen that the determination results of Co element in the sample solution without removal of Al matrix are obviously lower than those of the sample solution with removal of Al matrix by using the present cluster digestion device, and the high content of Al matrix has interference to the determination of Co element. In the present method, the removal of Al matrix by secondary digestion with HF can ensure the accuracy of the determination results and eliminate the interference of the matrix to the element determination.

[0238] Comparative Example 1:

[0239] Comparison test of influence of condensation reflux atomizer and no condensation reflux atomizer on determination of Pb element in alumina-based catalyst sample loaded with Pb element.

[0240] The use of the condensing reflux atomizer can effectively prevent the volatile loss of volatile elements in the digestion process. The sample of the alumina-based catalyst loaded with Pb elements was treated by using the present agglomerated digestion device, and the operation process was described in Example 3. In the comparative column, the operation conditions except for not using the condensing reflux atomizer were also described in Example 3. The sample solutions obtained by the two pretreatments were determined, and the results are shown in Table 5-1.

[0241] Table 5-1 Determination results by using condensing reflux and not using

[0242]

[0243] As can be seen from the results in Table 5-1, by using the present agglomerated digestion device, the condensing reflux atomizer and not using the condensing reflux atomizer, the comparison results are obvious. Without using the condensing reflux atomizer, more Pb elements are lost, and the use of the condensing reflux atomizer can obviously avoid the loss of Pb elements.

[0244] Of course, the present application can also have other various embodiments, and those skilled in the art can make various corresponding changes and modifications according to the present application without departing from the spirit and essence of the present application. However, these corresponding changes and modifications should all belong to the protection scope of the claims of the present application.

Claims

1. A method for the procedural digestion and separation of aluminum fluoride, characterized in that, include: The catalyst supported on alumina with metal elements is placed in the reaction vessel of the aggregated digestion device, hydrochloric acid and / or nitric acid are added, the digestion program is set, inert gas is introduced for pre-pressurization, and a first digestion is performed while the condenser reflux atomizer is turned on. After the program is completed, hydrofluoric acid is added, the digestion program is set, and a second digestion is performed. After digestion, a cooling crystallization process is initiated to separate the clear sample solution and solid to be tested. The solid is dried and calcined to obtain aluminum fluoride crystals. The sample solution is used for the detection of metal element content. The aggregated digestion device includes: a main body, a reaction vessel, and a condenser reflux atomizer; the main body includes a chamber, a front door, an upper door, a display screen, a control panel, a base, and a microwave generating system. The chamber is located inside the main body and is opened or closed by the front door. The chamber is a polyhedron, with its left and right sides and front and rear sides being symmetrical, or its diagonal sides being symmetrical, and its top and bottom sides being symmetrical, consisting of at least eight inner surfaces; the upper door is located on the top of the main body, and the display screen and control panel are located on the top surface or one side of the main body. The generating system is connected to the chamber. The base is not a turntable type, but rather a chassis fixed to the bottom of the chamber. The reaction vessel is placed on the base of the chamber. The condenser reflux atomizer includes a condenser inlet, a reflux pool, a reflux pool outlet, a condenser tube, an atomizer generator, a condenser water inlet, and a condenser water outlet. The lower end of the condenser tube communicates with the reflux pool, and the side of the reflux pool communicates with the atomizer generator through a sealing ring. The bottom of the condenser reflux atomizer has a condenser lower outlet, which communicates with the reaction vessel. The atomizer is a glass concentric atomizer with a capillary tube at its center. The capillary tube is parallel to the airflow of the carrier gas. The carrier gas is introduced through an external gas inlet on one side of the device. The airflow quickly passes through the end of the capillary tube and meets the carrier liquid in the atomizer at the nozzle, shearing the liquid to form tiny droplets. The tiny droplets are ejected with the carrier gas and condensed by the condenser tube to form condensate. The condensate flows back into the reflux pool and then into the reaction vessel. The upper part of the reaction vessel is provided with an external interface for communication with an external inert gas.

2. The method according to claim 1, characterized in that, The metallic element includes at least one of nickel, cobalt, molybdenum, platinum, palladium, lead, iridium, and ruthenium.

3. The method according to claim 1, characterized in that, The catalyst contains 10wt% to 98wt% alumina and has a particle size of less than 74 μm after grinding. The catalyst is dried at 105℃ to 120℃ for 100 min to 150 min, cooled, and then placed in the reaction vessel of the aggregated digestion device.

4. The method according to claim 1, characterized in that, The inert gas is at least one of nitrogen, helium, and argon, with a flow rate of 0.5~2.0 L / min and a pressure of 0.5~5.0 MPa.

5. The method according to claim 1, characterized in that, The hydrochloric acid and / or nitric acid are added at a ratio of 5.0 mL to 10.0 mL acid to 1.0 g catalyst, the amount of catalyst added is 1.0 g to 50.0 g, the mass concentration of the hydrochloric acid is 10% to 37%, and the mass concentration of the nitric acid is 40% to 68%. When hydrochloric acid and nitric acid are added simultaneously, the ratio of hydrochloric acid to nitric acid is 1:1 to 4:

1. The temperature of the first digestion is 120 ℃ to 200 ℃, the pressure is less than 5.0 MPa, and the time is 30 min to 120 min.

6. The method according to claim 1, characterized in that, The hydrofluoric acid is added at a ratio of 5.0 mL to 10.0 mL hydrofluoric acid / 1.0 g catalyst, the amount of catalyst added is 1.0 g to 50.0 g, the mass concentration of the hydrofluoric acid is 20% to 40%, the temperature of the secondary digestion is 80 ℃ to 180 ℃, the pressure is less than 5.0 MPa, and the time is 30 min to 120 min; the temperature of the crystallization is 15 ℃ to 25 ℃, and the time is 120 min to 240 min.

7. The method according to claim 1, characterized in that, The drying temperature is 105℃~120℃, the calcination temperature is 450℃~600℃, and the time is 100 min~200 min; the aluminum fluoride crystal is α-crystal AlF3 with a specific surface area greater than 40 m². 2 / g, pore size greater than 50 angstroms.

8. The method according to claim 1, characterized in that, The external connections of the machine body include an external gas inlet and a gas cylinder.

9. The method according to claim 1, wherein the carrier gas in the atomizing generator is an inert gas, at least one of nitrogen, helium and argon, with a flow rate of 0.05~1.0 L / min and a pressure of 0.1~0.5 MPa; the carrier liquid is a dilute acid solution, wherein the dilute acid solution is hydrochloric acid and / or nitric acid, wherein the mass concentration of the hydrochloric acid and / or nitric acid is 0.5~5.0%, and the flow rate of the carrier liquid is 0.1~2.5 mL / min.

10. A method for detecting the content of metal elements in a catalyst, characterized in that, The catalyst is digested using the method described in any one of claims 1-9 to separate aluminum fluoride, and then the content of each metal element is determined.

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