Method for separating aluminum fluoride through program digestion

Abstract

The invention discloses a method for separating aluminum fluoride through programmed digestion, which comprises the following steps: putting a catalyst which takes aluminum oxide loaded with metal elements as a carrier into a reaction container of a gathering type digestion device, adding hydrochloric acid and / or nitric acid, setting a digestion program, introducing inert gas for pre-pressurization, carrying out primary digestion, and starting a condensation reflux atomizer at the same time; after the procedure is finished, hydrofluoric acid is added, a digestion procedure is set, and secondary digestion is carried out; and after digestion is completed, carrying out cooling crystallization and separation to obtain a to-be-detected clear sample solution and a solid, drying and roasting the solid to obtain an aluminum fluoride crystal, and using the liquid for detecting the content of metal elements. The method disclosed by the invention is applied to digestion treatment of an aluminum oxide sample loaded with metal elements, the sample treatment range is large, digestion is complete, the elements are free from volatilization loss, and AlF3 in the alpha crystal form is separated through program digestion of the digestion device.

Description

Technical Field

[0001] The invention relates to the technical field of digestion and chemical separation, and in particular to a method for separating aluminum fluoride by programmed digestion. Background Art

[0002] Microwave is an electromagnetic wave with a frequency in the range of 300MHz to 300000MHz, that is, an electromagnetic wave with a wavelength in the range of 100cm to 0.1cm, also known as ultra-high frequency, located between infrared radiation and radio waves in the electromagnetic spectrum. It has been widely used in food, textiles, plastics, geology, metallurgy, coal, biomedicine, petrochemicals, environmental monitoring, sewage treatment, battery manufacturing, cosmetics and other fields. The microwave frequencies used in industry mainly include 915±25MHz, 2450±13MHz, 5800±75MHz, 22125±125MHz, etc. Among them, the most widely used frequency is 2450±13MHz, and the output power is 600W~800W. It can release about 200kJ of energy in just a few minutes, causing the molecules of the medium to vibrate about 2.45 billion times per second. The friction between the molecules of the medium causes the temperature of the medium to rise, so that the inside and outside of the medium material are heated up almost at the same time, forming a body heat source state, which greatly shortens the heat conduction time in conventional heating. When the condition is that the dielectric loss factor is negatively correlated with the medium temperature, the material is heated evenly inside and outside.

[0003] At present, the widely used microwave digestion instruments mainly utilize the heating advantages and characteristics of microwaves. After adding acid to the sample to be digested in the special plastic digestion tank, a strong polar solution is formed. The heating properties of microwaves are utilized to heat the solution inside and outside at the same time, which makes the heating faster and more uniform, thus improving the efficiency. Microwave digestion is generally carried out in a closed digestion tank. The pressure system can produce overheating, heating to a temperature higher than the boiling point under normal pressure, greatly improving 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 carry out some projects that cannot be carried out by conventional wet digestion. However, the amount of samples processed by traditional closed microwave digestion devices is relatively limited, and the maintenance amount for organic samples is usually no more than 0.5g, and the maintenance amount for inorganic samples is no more than 1.0g. Traditional ultra-high pressure digestion reaction tanks have large batch processing capacity and are suitable for large-scale sample processing. The furnace cavity is strong and not easy to deform; but they consume a lot of energy, are bulky, have high prices, high operating and maintenance costs, and have low safety factors.

[0004] In addition, due to the uneven distribution of microwave fields in common microwave digestion chambers, the samples in the chamber are prone to receiving microwaves unevenly, which affects the digestion effect. The usual solution is to rotate the plate so that each sample receives microwaves as evenly as possible. However, the temperature and pressure changes of the samples before and after heating are relatively large during the cycle, and the turntable design cannot fix the digestion tank. From a safety perspective, there are certain shortcomings.

[0005] According to the power emission mode, microwaves are divided into pulse microwaves and non-pulse microwaves. The traditional fixed power output is characterized by switch-type pulse microwaves. This control mode is not only difficult to control, but may also directly affect the digestion effect. The current microwave development direction is automatic power frequency conversion control and non-pulse technology, which is characterized by automatic power change and non-pulse microwave output. The advantage is that there is no need to turn off microwave emission. Under the condition of continuous microwave emission, the microwave power output is automatically and linearly changed according to the temperature and pressure feedback signal, the reaction state is adjusted, and the temperature control is more accurate, ensuring the safety and smooth progress of the experiment.

[0006] Alumina-based catalyst is a catalyst that uses alumina as a carrier and fixes active ingredients such as nickel, cobalt, molybdenum, platinum, palladium and other metal elements or their oxides on alumina. More than 70% of the active alumina is used as a catalyst carrier and is widely used in the petroleum refining industry and the chemical industry. Alumina is one of the most commonly used industrial raw materials and has extremely important applications in the fields of ceramics, refractory materials, medicine, catalysis, etc. Due to its advantages such as good mechanical strength, good thermal stability and chemical stability, suitable isoelectric point, adjustable surface acidity and alkalinity, and a variety of different crystal phase structures, alumina has become the most widely used catalyst carrier in the chemical and petroleum industries, playing an important role in the cracking of petroleum components, hydrorefining, hydrodesulfurization, reforming of hydrocarbons to produce hydrogen, purification of gaseous oil components, and purification of automobile exhaust.

[0007] As a catalyst carrier, alumina carrier refers to white powder or formed alumina solid, which is the most widely used catalyst carrier, accounting for about 70% of industrial supported catalysts. In many industrial catalytic processes, alumina is not only used as a catalyst itself, but also used as a carrier of catalyst active components in large quantities. Moreover, with the improvement of the forming method of activated alumina catalyst carrier, a variety of methods are applied to the catalyst carrier industry, such as block making, granulation, compaction, balling, extrusion, etc. Therefore, it can be a catalyst carrier in various shapes, such as columnar, annular, spherical, pressed tablets, granular, and extruded strips.

[0008] When the chemical composition of alumina-based catalysts is usually tested, the traditional method is to use K 2 CO 3 、Na 2 CO 3Alkali metal carbonates or hydroxides are used as solvents and melted together with the alumina sample at 1000°C in a platinum dish. While the Al element is dissolved, K is newly introduced. + 、Na + Elements such as ions cause the detection background to increase, increase matrix interference, and affect the accuracy of the detection. The methods for determining metal content usually include plasma emission spectrometry, 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] Commonly used methods for eliminating interference in spectral analysis include matrix matching method or internal standard method, which aims to eliminate the influence of fluctuations in analytical conditions on the intensity of analytical lines. For example, Ye Yuqiong et al. proposed using the atomic emission spectrometry powder method, selecting the best electrode shape, adding spectral corrosion inhibitors and internal standard elements for determination in the "Simultaneous Emission Spectrometry Determination of Platinum and Phosphorus in Alumina-based Catalysts" published in "Metallurgical Analysis" in 1993; Cheng Xichun et al. proposed using aqua regia (15 mL of concentrated nitric acid and 45 mL of concentrated hydrochloric acid) to dissolve the sample and using yttrium as the internal standard element for determination in "ICP-AES Internal Standard Determination of Palladium Content in Alumina-based Catalysts" published in "Fujian Analysis and Testing" in 2016.

[0010] The sampling quality of solid samples processed by existing microwave digestion instruments is usually limited, mainly due to the constraints of digestion container size, digestion chamber design, etc. Therefore, when analyzing trace and ultra-trace elements in solid samples, existing microwave digestion instruments are difficult to meet the measurement requirements. Therefore, it is worthwhile to further study and develop the design of microwave digestion instruments that use large-volume digestion containers and digestion chambers to achieve efficient digestion.

[0011] In addition, due to the characteristics of the instrument itself used in element testing, the matrix matching method or internal standard method is not suitable for high-concentration matrices. In particular, the determination of low-content impurity metals will still be affected to varying degrees, making the measurement results unable to meet the accuracy requirements of the method.

[0012] Through experimental research, it was found that since the aluminum concentration in the dissolved alumina solution is 40% to 60%, there is serious spectral interference in the determination of loaded metal elements, such as Al loaded with Pt element. 2 O 3 When determining the Pt element in the base catalyst, the Pt analysis spectrum lines are 265.945nm, 214.423nm, etc. If the Al matrix is ​​dissolved in the sample, the Pt analysis spectrum will be cut due to the interference of the Al matrix, resulting in a low measurement result.

[0013] At present, in the synthesis technology of aluminum fluoride, there are different conditions for the production of aluminum fluoride of α-AlF3, β-AlF3 and γ-AlF3. For example, CN95115476 "Fluorination catalysts for fluorinated halogenated hydrocarbons" proposes the use of SiO 2 For γ-Al 2 O 3 Fluorination is carried out at 150℃~300℃ with a mixture of anhydrous hydrogen fluoride and nitrogen as well as pure sewage hydrogen fluoride to load chromium, cobalt and magnesium catalysts to synthesize fluorinated halogenated hydrocarbons.

[0014] Chinese patent CN2748147Y discloses an ultrasonic microwave digestion and extraction device, including: a box, a magnetron, a waveguide, a sample bottle, a microwave power supply, a reflux condenser, a condenser sleeve, an electronic control system, the electronic control system is composed of a microcontroller, the box is a hexahedron made of metal plates, a door that can be opened and closed by a hinge is installed on the front of the box, a microwave radiation cavity is formed by a metal partition in the box, the sample bottle is placed in the microwave radiation cavity, one end of the reflux condenser is inserted into the mouth of the sample bottle through a sleeve fixed to the top of the box by a nut, and is fixed to the top of the box by a positioning ring. This technology installs ultrasound and microwaves on the device box, and the box structure is a conventional hexahedron. The ordinary box structure and conventional microwave function may cause incomplete digestion of large mass samples; in addition, this technology has a reflux condenser, but volatile elements are easy to remain in the reflux tube wall, and the volatile residue cannot be completely effectively refluxed by cooling alone.

[0015] Chinese patent CN205301023U discloses a normal pressure sealed pollution-free digester, which consists of a ground-mouth triangular flask, a vertical condenser, a solution backflow prevention bottle, a toxic gas absorption bottle and a porous plate, characterized in that the ground-mouth triangular flask is connected to a vertical condenser, the upper side of the vertical condenser is connected to the solution backflow prevention bottle through an air guide tube, the solution backflow prevention bottle is connected to the toxic gas absorption bottle through an air guide tube, the outlet of the air guide tube is blocked by a porous plate and extends downward to the bottom of the toxic gas absorption bottle, a certain amount of toxic gas absorption liquid is added to the toxic gas absorption bottle, and the absorption liquid isolates the sample solution to be digested from the ambient air. However, this technology only provides a device for digestion by conventional bottom heating condensation, and conventional sealed heating digestion is difficult to meet the digestion of oxide samples with large mass and a large amount of metal elements.

[0016] The sampling quality of solid samples processed by existing microwave digestion equipment is usually limited, mainly due to the constraints of digestion container size, digestion chamber design, etc. Therefore, when analyzing trace and ultra-trace elements in solid samples, existing microwave digestion equipment is difficult to meet the measurement requirements. Therefore, it is worthwhile to further study and develop the design of microwave digestion instruments that use large-volume digestion containers and multi-inner-surface digestion chambers to achieve efficient digestion. Summary of the invention

[0017] The object of the present invention is to provide a method for separating aluminum fluoride by programmed digestion. The method is applied to the digestion treatment of catalyst samples with aluminum oxide as a carrier to load metals. The sample quantity range is large, the digestion is complete, and there is no volatilization loss of elements. In addition, alpha crystalline AlF3 can be separated by programmed digestion of the digestion device.

[0018] To achieve the above-mentioned purpose, the present invention provides a method for separating aluminum fluoride by program digestion, which comprises: placing a catalyst with aluminum oxide loaded with metal elements as a carrier in a reaction vessel of an agglomerated digestion device, adding hydrochloric acid and / or nitric acid, setting a digestion program, introducing inert gas for pre-pressurization, performing a primary digestion, and simultaneously starting a condensation reflux atomizer; after the program is completed, adding hydrofluoric acid, setting a digestion program, and performing a secondary digestion; after the digestion is completed, entering a cooling crystallization program, performing cooling crystallization, separating to obtain a clarified sample solution and a solid to be tested, drying and roasting the solid to obtain aluminum fluoride crystals, and the sample solution is used for the detection of the metal element content;

[0019] The agglomerative digestion device comprises: a body, a reaction vessel, and a condensation reflux atomizer; the condensation reflux atomizer comprises a condenser inlet, a reflux pool, a reflux pool outlet, a condenser, an atomizer generator, a condenser water inlet, and a condenser water outlet, the lower end of the condenser pipe is connected to the reflux pool, and the side of the reflux pool is connected to the atomizer generator through a sealing ring; a condenser lower outlet is provided at the bottom of the condensation reflux atomizer, and the condenser lower outlet is connected to the reaction vessel;

[0020] The atomizer generator is a glass concentric atomizer, the center of which is a capillary tube, the capillary tube is parallel to the airflow of the carrier gas, the carrier gas is introduced through an external air inlet instrument port on one side of the body, the airflow quickly passes through the end of the capillary tube, meets the carrier liquid in the atomizer generator at the atomizer nozzle and shears the liquid to form tiny droplets, the tiny droplets are sprayed out with the carrier gas, condensed by the condenser tube to form condensate, the condensate droplets flow back into the reflux pool and into the reaction container; the upper part of the reaction container is provided with an external interface, which is connected to an external inert gas.

[0021] Furthermore, the metal element includes at least one of nickel, cobalt, molybdenum, platinum, palladium, lead, iridium and ruthenium.

[0022] Furthermore, the content of aluminum oxide in the catalyst is 10wt% to 98wt%, and the particle size of the catalyst after grinding is less than 74μm to obtain the best reaction effect. The catalyst is dried at 105℃ to 120℃ for 100min to 150min, cooled, and then placed in the reaction container of the agglomerated digestion device.

[0023] Furthermore, the carrier gas used in the atomization generator is at least one of nitrogen, helium and argon, with a flow rate of 0.05 to 1.0 L / min and a pressure of 0.1 to 0.5 MPa; 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 to 5.0%, and the flow rate of the carrier liquid is 0.1 to 2.5 mL / min.

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

[0025] Furthermore, the amount of hydrochloric acid and / or nitric acid added is 5.0 mL to 10.0 mL of acid / 1.0 g of catalyst, the amount of the 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 primary digestion is 120° C. to 200° C., the pressure is less than 5.0 MPa, and the time is 30 min to 120 min.

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

[0027] Furthermore, the drying temperature is 105°C to 120°C, the calcination temperature is 450°C to 600°C, and the time is 100min to 200min; the aluminum fluoride crystal is an α-crystalline AlF 3 , with a specific surface area greater than 40m 2 / g, pore size greater than 50 angstroms.

[0028] Furthermore, the machine 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 machine body and is opened or closed by the front door. The cavity structure is a polyhedron, and the left and right sides and the front and back sides are respectively or all symmetrical planes, or the diagonal planes are symmetrical, and the upper and lower sides are symmetrical planes, and are composed of at least 8 inner surfaces; the upper 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 body, the microwave generating system is connected to the chamber, and the base is not a turntable type, but a chassis fixed to the bottom surface of the chamber; the reaction container is placed on the base of the chamber; the outside of the body is connected to an external gas inlet and a gas cylinder.

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

[0030] Furthermore, the chamber is a closed rectangular industrial resonant cavity; the chamber is made of stainless steel or polytetrafluoroethylene and is provided with a multi-layer anti-corrosion coating; the polytetrafluoroethylene is resistant to corrosion by acids, alkalis, organic solvents, etc.; the chamber is also provided with an exhaust system and a cooling system, and the exhaust volume in the chamber is not less than 1.0m 3 The chamber may also be equipped with an air cooling function to continuously cool the reaction container and display the temperature and pressure in real time.

[0031] Furthermore, the machine door is equipped 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; an observation window is also provided on the machine door, and a heat dissipation net is provided on the outside of the machine body, and the mesh size of the metal grid or wire mesh in the observation window and the heat dissipation net is 0.02 to 0.2 mm.

[0032] Furthermore, the body can be designed as one or more modes, not limited to Figure 1 The two modes shown, and the reaction conditions of each mode can be controlled by program.

[0033] Furthermore, the shape of the reaction container is selected from spherical, cylindrical, cubic, and polyhedral.

[0034] Furthermore, the material of the reaction container is one of tertiary tetrafluoroethylene (PTFE), perfluoroalkoxy (PFA), modified polytetrafluoroethylene (TFM) and quartz. These materials are permeable and propagable to microwaves, so these materials will not absorb microwave energy or absorb very little microwaves, and the ability of the sample inside the reaction container to absorb microwaves is enhanced by penetration.

[0035] Furthermore, the outer wall of the reaction vessel wall is a waveguide layer, which is conducive to the penetration of microwaves and good temperature conduction. Its material should be a non-polar molecular substance. Due to the accelerated frequency change of microwaves, the molecules will tend to collide and rub against each other, and the reaction will be violent. In order to improve the safety of operation, a material with small deformation under high temperature and high pressure, small permeability, good recovery under high temperature and heavy pressure, and high surface finish can be selected. For example, polyetheretherketone (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 uses PEEK fiber, which contains 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.

[0036] Furthermore, the volume of the reaction container is 200 mL to 2000 mL; the operating temperature of the reaction container is 0 to 350° C., and at the highest temperature, the internal pressure can reach 5.0 MPa.

[0037] Furthermore, a reagent is introduced into the reaction container, and the reagent is an acid, a 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 water and sodium hydroxide, and the other reagent required for digestion is hydrogen peroxide.

[0038] Furthermore, an optical fiber temperature sensor is provided in the chamber, and the chamber adopts optical fiber temperature control, which will not be interfered by the microwave field, has high measurement accuracy and good safety. Temperature control range: 0-350℃; temperature control accuracy: ±0.5℃.

[0039] Furthermore, there are internal components between the chamber and the body, and the internal components are a magnetron, a diode, a refrigerator, a transformer, and a fan.

[0040] Furthermore, 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 microwaves of the microwave generating system are non-pulse continuous automatic frequency conversion control, have a long service life, and emit electromagnetic waves with good uniformity.

[0041] Furthermore, the control system adopts a high-precision temperature and pressure control system. The operator can observe the data and curves of temperature and pressure changes through the control panel to understand the operation of the machine, monitor temperature and pressure abnormalities in real time, and ensure safety. Pressure control range: 0-5.0MPa, pressure control accuracy: 0.01MPa, overpressure can be automatically adjusted and microwave emission can be stopped, and an alarm can be automatically issued.

[0042] Furthermore, the refrigerator is a semiconductor refrigerator for cooling the interior of the chamber, with an operating temperature of 0°C to 25°C and a control temperature of 15°C to 20°C.

[0043] Furthermore, an air outlet is installed on the side of the machine body.

[0044] The present invention also provides a method for detecting the content of metal elements in a catalyst. The catalyst is digested by the above method to separate aluminum fluoride, and then the content of each metal element is determined.

[0045] The reaction container is placed in the chamber and on the base, and the reaction container is fixed in the chamber by a fixing ring and screws; the operation of the entire concentrated digestion device is controlled by a control panel, and the display screen displays all programs in real time. When the device is started, the front door and the upper door are automatically locked and cannot be opened manually; the transformer supplies the diode, and the diode is connected to the magnetron to send microwaves through the cavity layer into the chamber, forming 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 in temperature and pressure in the chamber in real time; the volatile gas leaked in the chamber is discharged through the fan, and the fan is connected to the exhaust port on the side of the machine body, and the residual heat inside the chamber is dissipated through the heat dissipation net on the side of the machine body.

[0046] The method for separating aluminum fluoride by program digestion of the present invention can digest the aluminum oxide-based catalyst by using a clustering digestion device, and can separate α-type aluminum fluoride crystals by program digestion, and solve the problem of aluminum matrix interference in spectral analysis at the same time. The method for separating aluminum fluoride by program digestion of the present invention can realize the aggregation of microwaves on the conduction path, greatly improve the microwave efficacy, realize the digestion of samples under micro-pressure or low pressure through efficient radiation, and obtain complete digestion at the aggregation position, so that the operation safety can be improved, the digestion speed is also accelerated, and a large amount of samples can be processed at one time, which greatly improves the deficiency of small sample amount in the existing microwave digestion. Since in the process of analyzing various metal elements in the aluminum oxide-based catalyst loaded with metal elements, the aluminum matrix in the sample solution will produce different degrees of matrix interference on the metal element to be measured, by applying the present invention, aluminum fluoride crystals can be generated to remove the aluminum matrix in the solution, thereby eliminating the matrix interference of spectral analysis, the method is simple and direct, greatly improves the accuracy of the results of the elements to be measured, and plays an important role in improving the quality of catalyst products and ensuring the smooth operation of the production process.

[0047] The method for separating aluminum fluoride by program digestion of the present invention is to directly act on the sample by focusing microwaves, perform efficient radiation, digest the sample under micro-pressure and low pressure, and operate safely. The microwave focusing effect can accelerate the reaction speed, reduce the amount of reagents used, and improve the efficiency of the reaction. The volume of the chamber of the present invention is large, and a large amount of samples can be processed at one time, which improves the problem that the existing digestion device processes a small amount of samples and is difficult to enrich low-content samples. The high temperature and high pressure generated in the traditional microwave closed digestion reaction will cause many elements and compounds to be in a gaseous state. If the sealing effect is not good, it will cause serious element loss, affecting the consistency of sample digestion. The present invention solves the problem of volatile element loss through the design of condensation atomization reflux. The volatile residual phase attached to the wall of the condensation tube is dissolved by the tiny droplets sprayed by the condensation reflux atomizer, condensed by the condensation tube, and the condensed droplets flow back into the reflux tank and into the reactor. At the same time, the present invention does not need to adopt a turntable type, and the fixed chassis 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 cavity are tightly combined without microwave leakage. The concentrated microwave digestion device uses a temperature and pressure dual control system to control the internal pressure and temperature, and displays it in real time. When the pressure in the reaction vessel exceeds the set protection value, the microwave will automatically stop heating. Using a high-precision temperature and pressure control system, the operator can understand the operation of the machine by observing the data and curves of temperature and pressure changes. Its software module can actively stop running when the slope is out of control, greatly reducing the possibility of tank explosion. It has real-time temperature and pressure abnormality monitoring. When the high-precision temperature and pressure control system fails, the system will sense and stop running in time as a backup measure to ensure safety.

[0049] The agglomerative digestion device of the present invention mainly includes a body, a reaction container, and a condensation reflux atomizer. Before the reaction, the sample is added to the reaction container, the reaction container is placed in the chamber, fixed, connected to the condensation reflux atomizer, and the condensation reflux atomizer is turned on at the same time. The acid reagent required for the digestion reaction is introduced through the inlet of the condensation reflux atomizer. During the sample digestion process, there may be a violent instantaneous reaction that causes element volatilization. The condensation reflux atomizer should be turned on in advance before the digestion reagent is introduced to maintain condensation reflux to prevent instantaneous volatilization and avoid element loss. Open the control panel, set the reaction temperature, time, and pressure, and after the parameters are set, start the program, the digestion device starts working, and at the same time, the carrier gas is turned on and the carrier liquid is introduced, the atomizer works, and the volatile phase remaining on the condensation tube wall during the reaction is atomized into extremely fine droplets by the atomizer and returned to the reaction container under the action of condensation.

[0050] The method for separating aluminum fluoride by programmed digestion of the present invention realizes direct microwave concentration on the sample through the design of 8 or more symmetrical inner surfaces of the chamber, thereby obtaining efficient radiation, shortening the reaction time and achieving complete digestion.

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

[0052] The method for separating aluminum fluoride by programmed digestion of the present invention operates under micro-pressure or low pressure, thereby improving the safety of the digestion reaction and effectively avoiding the potential safety hazards brought by high-pressure reactions to the digestion process.

[0053] The method for separating aluminum fluoride by programmed digestion of the present invention can separate α-type aluminum fluoride crystals with stable properties.

[0054] The method for separating aluminum fluoride by program digestion of the present invention can completely dissolve the metal elements loaded in the aluminum oxide catalyst.

[0055] The spectrum analysis liquid obtained after separating aluminum fluoride by the method for separating aluminum fluoride by programmed digestion of the present invention effectively eliminates the interference problem caused by the aluminum matrix in the spectrum analysis, and the method is simple and easy to operate. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 This is a front view of the external structure of the concentrated condensation digestion device of the present invention;

[0057] Figure 2 It is a schematic diagram of the structure of the condensation reflux atomizer of the present invention;

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

[0059] Figure 4 is a schematic diagram of a fixing ring of a reaction vessel of the present invention;

[0060] Figure 5 It is a schematic diagram of the installation of internal components between the chamber and the body;

[0061] Figure 6 It is a structural schematic diagram of the atomizing generator of the present invention;

[0062] Figure 7 Example 1 α-AlF 3 XRD pattern of the product;

[0063] Figure 8 The α-AlF obtained in Example 1 3 SEM image of the product (magnification: 800);

[0064] Fig. 9 The α-AlF obtained in Example 2 3 XRD pattern of the product;

[0065] Fig.10 The α-AlF obtained in Example 23 SEM image of the product (magnification: 800);

[0066] Fig.11 The α-AlF obtained in Example 3 3 XRD pattern of the product;

[0067] Fig.12 The α-AlF obtained in Example 3 3 SEM image of the product (magnification: 800).

[0068] Description of reference numerals: 1, machine body; 2, front machine door; 3, upper machine door; 4, chamber; 5, reaction vessel; 6, condensation reflux atomizer; 7, communication port; 8, display screen; 9, control panel; 10, gas cylinder; 11, external gas inlet; 12, condenser inlet; 13, reflux tank outlet; 14, reflux tank; 15, condenser water inlet; 16, condenser water outlet; 17, condenser 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 vessel outer wall; 28, reaction vessel inner wall; 29; external interface; 30, temperature sensor; 31, pressure sensor; 32, base; 33, screw 1; 34, clip 1; 35, additional layer; 36, inner interlayer; 37, clip 2; 38, screw 2; 39, screw 3; 40, clip 3; 41, clip 4; 42, screw 4; 43, 46, 49 magnetron; 44, 47, 50 diode; 45, refrigerator; 48, transformer; 51, fan; 52, atomizer nozzle; 53, capillary. DETAILED DESCRIPTION

[0069] The method for separating aluminum fluoride by programmed digestion of the present invention comprises: placing a catalyst with aluminum oxide loaded with metal elements as a carrier in a reaction container of an agglomerated digestion device, adding hydrochloric acid and / or nitric acid, setting a digestion program, introducing inert gas for pre-pressurization, performing a primary digestion, and simultaneously starting a condensation reflux atomizer; after the program is completed, adding hydrofluoric acid, setting a digestion program, and performing a secondary digestion; after the digestion is completed, entering a cooling crystallization program, performing cooling crystallization, separating to obtain a clarified sample solution to be tested and a solid, drying and roasting the solid to obtain aluminum fluoride crystals, and the liquid is used for detecting the content of the metal element.

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

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

[0072] The atomizer 20 is a glass concentric atomizer, the center of which is a capillary 53. The capillary 53 is parallel to the airflow of the carrier gas. The carrier gas is introduced through the external air inlet port 11 on one side of the body 1. The airflow quickly passes through the end of the capillary 53, meets the carrier liquid in the atomizer generator 20 at the atomizer nozzle 52 and shears the liquid to form tiny droplets. The tiny droplets are sprayed out with the carrier gas, condensed through the condenser 17 to form condensate, and the condensate droplets flow back into the reflux tank 14 and into the reaction container 5; an external interface is provided on the upper part of the reaction container 5, which is connected to the external inert gas.

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

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

[0075] Furthermore, the atomizer generator 20 uses a carrier gas of at least one of nitrogen, helium and argon, with a flow rate of 0.05 to 1.0 L / min and a pressure of 0.1 to 0.5 MPa; 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 hydrochloric acid and / or nitric acid is 0.5 to 5.0%, and the flow rate of the carrier liquid is 0.1 to 2.5 mL / min.

[0076] Furthermore, the inert gas is at least one of nitrogen, helium and argon, with a flow rate of 0.5 to 2.0 L / min and a pressure of 0.5 to 5.0 MPa.

[0077] Furthermore, the amount of hydrochloric acid and / or nitric acid added is 5.0 mL to 10.0 mL of acid / 1.0 g of catalyst, the amount of catalyst added is 1.0 g to 50.0 g, the mass concentration of hydrochloric acid is 10% to 37%, and the mass concentration of 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 a single digestion is 120°C to 200°C, the pressure is less than 5.0 MPa, and the time is 30 min to 120 min.

[0078] Furthermore, the amount of hydrofluoric acid added is 5.0 mL to 10.0 mL of hydrofluoric acid / 1.0 g of catalyst, the amount of catalyst added is 1.0 g to 50.0 g, the mass concentration of hydrofluoric acid is 20% to 40%, the temperature of the secondary digestion is 80° C. to 180° C., the pressure is less than 5.0 MPa, and the time is 30 min to 120 min; the temperature of the crystallization is 15° C. to 25° C., and the time is 120 min to 240 min.

[0079] Furthermore, the drying temperature is 105°C to 120°C, the calcination temperature is 450°C to 600°C, and the time is 100min to 200min; the aluminum fluoride crystal is an α-crystalline AlF 3 , with a specific surface area greater than 40m 2 / g, pore size greater than 50 angstroms.

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

[0081] The chamber 4 is a polyhedron, and the left and right sides and the front and back sides are either symmetrical planes, or the diagonal planes are symmetrical, and the upper and lower sides are symmetrical planes. It is composed of at least 8 inner surfaces to achieve concentrated radiation of microwaves in the cavity.

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

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

[0084] Furthermore, the volume of the chamber 4 needs to be specifically designed according to the volume of the reaction container. The material of the chamber 4 is all stainless steel or polytetrafluoroethylene, and is provided with a multi-layer anti-corrosion coating; polytetrafluoroethylene is resistant to corrosion by acids, alkalis, organic solvents, etc.

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

[0086] Furthermore, the front door 2 and the upper door 3 are equipped with double or triple independent interlocking sensing devices, the power is cut off when they are opened, and the microwave generating system cannot work when the door is not closed.

[0087] Furthermore, an observation window is provided on the front door 2, and the mesh size of the metal grid or wire mesh in the observation window is 0.02-0.2 mm, which effectively prevents microwaves from leaking out.

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

[0089] Furthermore, the shape of the reaction container 5 is selected from spherical, cylindrical, cubic, and polyhedral shapes, and the upper portion of the reaction container has an external interface connected to an external inert gas.

[0090] Furthermore, the material of the reaction container 5 is one of tertiary tetrafluoroethylene (PTFE), perfluoroalkoxy (PFA), modified polytetrafluoroethylene (TFM) and quartz. These materials are permeable and propagable to microwaves, so these materials will not absorb microwave energy or absorb very little microwaves, and the ability of the sample inside the reaction container to absorb microwaves is enhanced by penetration.

[0091] Furthermore, the outer wall 27 of the reaction vessel wall 5 is a waveguide layer, which is conducive to the penetration of microwaves and good temperature conduction. Its material should be a non-polar molecular substance. Due to the accelerated frequency change of microwaves, the molecules will tend to collide and rub against each other, and the reaction will be violent. In order to improve the safety of operation, a material with small deformation under high temperature and high pressure, small permeability, good recovery under high temperature and heavy pressure, and high surface finish can be selected. For example, polyetheretherketone (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 uses PEEK fiber, which contains 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] Furthermore, the volume of the reaction container 5 is 200 mL to 2000 mL.

[0093] Furthermore, the operating temperature of the reaction vessel 5 is 0-350° C., and at the highest temperature, the internal pressure can reach 5.0 MPa.

[0094] Furthermore, a reagent is introduced into the reaction container, and the reagent is an acid, a 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 water and sodium hydroxide, and the other reagent required for digestion is hydrogen peroxide.

[0095] Furthermore, an optical fiber temperature sensor is provided in the chamber 4. The chamber 4 uses optical fiber temperature control, which is not interfered by the microwave field, has high measurement accuracy and good safety. Temperature control range: 0-350°C; temperature control accuracy: ±0.5°C.

[0096] Further, refer to Figure 5 , internal components between the chamber 4 and the body 1, the internal components are magnetrons 43, 46, 49, diodes 44, 47, 50, a refrigerator 45, a transformer 48, and a fan 51.

[0097] Furthermore, 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-pulse continuous automatic frequency conversion control, has a long service life, and emits electromagnetic waves with good uniformity.

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

[0099] Furthermore, the refrigerator 45 is a semiconductor refrigerator for cooling the interior of the chamber, with an operating temperature of 0°C to 25°C and a control temperature of 15°C to 20°C.

[0100] Furthermore, a heat dissipation net and an exhaust port are installed on the side of the body 1.

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

[0102] The specific digestion process of the method for separating aluminum fluoride by program digestion is to add the sample into the reaction container 5 before the reaction, put the reaction container 5 into the chamber 4, fix it, connect the condensation reflux atomizer, and turn on the condensation reflux atomizer at the same time. The acid reagent required for the digestion reaction is introduced through the reagent addition port of the condensation reflux atomizer. During the sample digestion process, especially the digestion of organic samples, there may be a violent instantaneous reaction that causes element volatilization. The condensation reflux atomizer should be opened in advance before the digestion reagent is introduced to maintain condensation reflux to prevent instantaneous volatilization and avoid element loss. Open the control panel 9, set the reaction temperature, time, and pressure, and after the parameters are set, start the program, the digestion device starts working, and at the same time, the carrier gas is turned on and the carrier liquid is introduced, and the atomizer works. The volatile phase remaining on the condensation tube wall during the reaction is atomized into extremely fine droplets by the atomizer and returned to the reaction container 5 under the action of condensation.

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

[0104] Embodiment 1:

[0105] The atomizer 20 uses nitrogen as carrier gas with a flow rate of 0.05 L / min and a pressure of 0.1 MPa; the carrier liquid is dilute hydrochloric acid with a mass concentration of 0.5% and a flow rate of 0.1 mL / min.

[0106] The inert gas external to the reaction container 5 is nitrogen with a flow rate of 0.5 L / min and a pressure of 0.5 MPa.

[0107] The cavity structure is a polyhedron, with left and right sides and front and back sides either being symmetrical planes, or diagonal planes being symmetrical, and top and bottom being symmetrical planes, and is composed of 8 inner surfaces.

[0108] Chamber 4 is a closed rectangular industrial resonant cavity. Chamber 4 is made of stainless steel and has a multi-layer anti-corrosion coating. Chamber 4 is equipped with an exhaust system and a cooling system. A centrifugal fan is installed in the chamber with an exhaust volume of 5.0m 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.

[0109] An observation window is provided on the front door 2, 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 machine body 1 can be designed to have two chambers, and the reaction conditions of each chamber can be controlled by a program.

[0111] The reaction container 5 is spherical in shape, and has an external interface on the upper portion thereof, which is connected to an external inert gas.

[0112] The material of the reaction container 5 is polytetrafluoroethylene (PTFE), which is permeable and propagable to microwaves.

[0113] 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. The material of the waveguide layer is a non-polar molecular substance, using PEEK fiber, which contains 25% carbon fiber.

[0114] The volume of the reaction container 5 is 200 mL. The working temperature of the reaction container 5 is 0-350° C. At the highest temperature, the internal pressure can reach 5.0 MPa.

[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) Comparative test of spike recovery

[0117] Using this method, accurately weigh 1.0g (accurate to 0.001g) of the alumina-based catalyst sample loaded with Ni element, weigh three parallel samples respectively, add 10.0mg / L, 15.0mg / L and 20.0mg / L of Ni standard substance (taken from 1000mg / L Ni standard solution, commercially available inorganic standard solution) to two of them, use a concentrated digestion device according to the method of the present invention, set the digestion program as shown in Table 1-1, add 5.0mL of 10% hydrochloric acid (commercially available, high-grade pure), the temperature is 120°C, the pressure is 0.5Mpa, the time is 30min, perform a primary program digestion, add 5.0mL of 25% hydrofluoric acid (commercially available, high-grade pure), the temperature is 80°C, the pressure is 0.5Mpa, the time is 30min, perform a secondary program digestion, and after the digestion is completed, enter the cooling crystallization program to perform cooling crystallization, the crystallization temperature is 15°C, and the time is 120min. Separate the clear sample solution and solid to be tested, dry and calcine the solid at 105°C and 450°C for 100 min to obtain aluminum fluoride crystals, separate the liquid and transfer it to a 100 mL volumetric flask for determination of Ni content. The concentration standard solutions of Ni element series 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.

[0118] Table 1-1 Digestion program settings

[0119]

[0120] In the comparative example, the sample was treated by direct wet digestion method, and then the sample was treated by matrix matching method and internal standard method before determination.

[0121] Direct wet digestion sample processing method, accurately weigh 1.0g (accurate to 0.001g) of alumina-based catalyst sample loaded with Ni element, weigh 3 parallel samples respectively and place them in quartz crucibles, add 5.0mL of 10% hydrochloric acid (commercially available, high-grade pure), digest on a hot plate at 120°C for 30min, then add 5.0mL of 25% hydrofluoric acid (commercially available, high-grade pure), and continue digesting on the hot plate at 80°C for 30min. After digestion is completed, transfer the digestion solution to a 100mL volumetric flask to make up the volume for the detection of Ni element content.

[0122] The matrix matching method is that the Ni standard solution used in the determination process should contain a concentration that matches the Al element in the sample. After the direct wet digestion treatment, the aluminum element is not separated and removed, and is present in the sample solution in large quantities, with a concentration of about 43wt%. Therefore, the Ni standard solution is prepared into a matrix containing a concentration of 43wt% Al element for instrument detection. The Ni element series concentration standard solutions used for determination are 0mg / L (blank), 5.0mg / L, 10.0mg / L, 15.0mg / L, 20.0mg / L and 25.0mg / L, respectively, with an Al concentration of 43%. The element concentration value in the sample to be measured should fall within the linear range of the standard working curve.

[0123] The internal standard method is that the Ni standard solution used in the determination process should introduce an internal standard element to eliminate the interference caused by the Al element. In this experiment, Sn is selected as the internal standard element, so the Ni standard solution is prepared to contain the Sn internal standard element standard solution for instrument detection. The concentration of the Ni element series standard solution used 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, the concentration of the internal standard Sn is 10.0 mg / kg, and the element concentration value in the sample to be tested should fall within the linear range of the standard working curve.

[0124] Usually, the amount of spiked test should not be too large, and it is generally appropriate to be 0.5 to 2.0 times the content of the substance to be tested. Under certain working conditions of an inductively coupled plasma emission spectrometer (PerkinElmer, USA, model 5300DV), the samples treated by this digestion method and direct wet digestion were measured, and the concentration values ​​of Ni element in the sample solution before and after spiked were measured by this method, matrix matching method and internal standard method. The three methods were used to determine the concentration values ​​of Ni element in the sample solution before and after spiked, and the recovery rate was calculated. The results are shown in Table 1-2.

[0125] Table 1-2 Recovery test results

[0126]

[0127] It can be seen from the results in Table 1-2 that the results of the determination using the matrix matching method and the internal standard method after direct wet digestion before spike addition are lower than the results of the determination by this method; in the results of three groups of spike additions with different concentrations, the recovery rates of the Ni element of the method of the present invention are 101.50%, 100.60% and 98.80%, and the results are all above 95%. The recovery rate results are all higher than the results of the determination using the matrix matching method and the internal standard method after direct wet digestion. Due to the high Al content in the catalyst, there is a certain interference with the determination of the Ni element. Although the matrix matching method and the internal standard method have a certain correction effect on the determination of the Ni element, the accuracy is reduced to a certain extent compared with the results determined after the program digestion treatment using the present agglomerative digestion device. Therefore, after the program digestion treatment using the present agglomerative digestion device, the aluminum matrix in the sample is effectively removed, and the accuracy of the results is higher.

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

[0129] The sample treatment method containing Al matrix is ​​to not perform the secondary digestion step of adding HF acid to the alumina-based catalyst sample loaded with Ni element, and other operation steps remain unchanged, to investigate the influence of Al matrix and Al matrix removal on Ni element determination. By adding HF, AlF 3 Precipitation, with AlF 3 The Al matrix was removed in the form of a precipitate to obtain a sample solution with the Al matrix removed (Al content of about 30 μg / mL); in addition, a sample solution containing an aluminum matrix (Al content of about 43 wt%) was obtained by performing the same operation as the method except that HF ​​was not added. The sample solutions obtained by the two pretreatments were measured, and the results are shown in Tables 1-3.

[0130] Table 1-3 Determination results of Ni element in Al-containing matrix and Al-removed matrix

[0131]

[0132] It can be seen from the results in Tables 1-3 that by using the concentrated digestion device, the determination results of the Ni element in the sample solution without removing the Al matrix are significantly lower than those in the sample solution with the Al matrix removed. This indicates that the secondary HF digestion in this method to remove the Al matrix can ensure the accuracy of the determination results and eliminate the interference caused by the presence of the matrix to the element determination.

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

[0134] The material obtained by repeatedly washing and drying the filtered material after the above-mentioned catalyst sample loaded with Ni element was subjected to program digestion was scanned by X-ray diffraction spectrum, using an X-ray diffractometer (Malvern Panalytical, the Netherlands, model Sharp Shadow), Cu target, tube current 40mA, tube voltage 45KV, continuous scanning 2θ angle at 5° to 90°, step size 0.01°, such as Figure 7 The spectrum was analyzed by Highscore software and PDF database, and the result was AlF 3 (PDF 04-023-5575)α-type crystal.

[0135] (4) Scanning electron microscopy analysis test

[0136] The material obtained by repeatedly washing and drying the filtered material after the above-mentioned catalyst sample loaded with Ni element was analyzed by program digestion, and the acceleration voltage was 30kV, the resolution was 0.3nm, the vacuum degree was 270Pa, and the scanning electron microscope analysis results were 800 times as shown in the following figure. Figure 8 As shown, from Figure 8 It can be seen that the crystal is obviously cubic, which verifies the AlF 3 α-type crystals are cubic.

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

[0138] The specific surface area and pore volume of the material obtained by repeatedly washing and drying the filtered material after the above-mentioned catalyst sample loaded with Ni element was processed by program digestion (American Mack Company, model TriStar TM3000) were analyzed. The specific surface area and pore volume were 41.6187m 2 / g, 12.81nm.

[0139] Embodiment 2:

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

[0141] The inert gas external 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, with left and right sides and front and back sides either being symmetrical planes, or diagonal planes being symmetrical, and top and bottom being symmetrical planes, and is composed of 8 inner surfaces.

[0143] Chamber 4 is a closed rectangular industrial resonant cavity. Chamber 4 is made of stainless steel and has a multi-layer anti-corrosion coating. Chamber 4 is equipped with an exhaust system and a cooling system. A centrifugal fan is installed in the chamber with an exhaust volume of 5.0m3 / 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.

[0144] An observation window is provided on the front door 2, and the mesh of the metal grid or wire mesh of the observation window is 0.1 mm, which effectively prevents microwave leakage.

[0145] The machine body 1 is designed as two-mode chambers, and the reaction conditions of each chamber can be controlled by a program.

[0146] The reaction container 5 is cylindrical in shape, and has an external interface at the top thereof, which is connected to an external inert gas.

[0147] The material of the reaction container 5 is polytetrafluoroethylene (PTFE), which is permeable and propagable to 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. The material of the waveguide layer is a non-polar molecular substance, using PEEK fiber, which contains 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° C. At the highest temperature, the internal pressure can reach 5.0 MPa.

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

[0151] (1) Comparative test of spike recovery

[0152] Using this method, accurately weigh 50.0g (accurate to 0.001g) of alumina-based catalyst sample loaded with Pt element, weigh three parallel samples respectively, add 50.0mg / L, 100.0mg / L and 200.0mg / L of Pt standard substance (taken from 1000mg / L Pt standard solution, commercially available inorganic standard solution) to two of them, use a concentrated digestion device according to the method of the present invention, set the digestion program as shown in Table 2-1, add 400.00mL of 10% hydrochloric acid (commercially available 100.00mL nitric acid 40% (commercially available, high-grade pure) and 100.00mL nitric acid 40% (commercially available, high-grade pure), mixed acid, temperature 200°C, pressure 5.0Mpa, time 120min, perform a program digestion, add 500.0mL hydrofluoric acid 25% (commercially available, high-grade pure), temperature 180°C, pressure 5.0Mpa, time 120min, perform a secondary program digestion, after digestion is completed, enter the cooling crystallization program, perform cooling crystallization, crystallization temperature is 25°C, time 240min. Separate to obtain the clarified sample solution and solid to be tested, dry and roast the solid, the drying temperature is 105°C, the roasting temperature is 450°C, the time is 100min, obtain aluminum fluoride crystals, separate the liquid and transfer it to a 100mL volumetric flask to make up the volume for the detection of Pt element content. The concentrations of the Pt element standard solutions used in the 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.

[0153] Table 2-1 Digestion program settings

[0154]

[0155] In the comparative example, the sample was treated by direct wet digestion method, and then the sample was treated by matrix matching method and internal standard method before determination.

[0156] Direct wet digestion sample processing method. This method has a limited sample processing capacity and cannot achieve large mass weighing. Usually, the mass should be less than 15.0 g. Accurately weigh 10.0 g (accurate to 0.001 g) of alumina-based catalyst sample loaded with Pt element, weigh 3 parallel samples respectively and place them in a quartz crucible, add 20.0 mL of 10% hydrochloric acid (commercially available, high-grade purity) and 5.0 mL of 40% nitric acid (commercially available, high-grade purity) mixed acid, digest on a hot plate at 200°C for 100 min, then add 15.0 mL of 25% hydrofluoric acid (commercially available, high-grade purity), and continue digesting on the hot plate at 180°C for 60 min. After digestion is completed, transfer the digestion solution to a 100 mL volumetric flask to make up the volume for the detection of Pt element content.

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

[0158] The internal standard method is that the Pt standard solution used in the determination process should introduce an internal standard element to eliminate the interference caused by the Al element. In this experiment, Cd is selected as the internal standard element, so the Pt standard solution is prepared to contain the Cd internal standard element standard solution for instrument detection. The Pt element series concentration 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, respectively. The concentration of the internal standard Cd is 10.0 mg / kg, and the element concentration value in the sample to be tested should fall within the linear range of the standard working curve.

[0159] Usually, in the spiked test, the spiked amount should not be too large, and it is generally appropriate to be 0.5 to 2.0 times the content of the substance to be tested. Under certain working conditions of the inductively coupled plasma emission spectrometer (PerkinElmer, USA, model 5300DV), the samples treated by this digestion method and direct wet digestion were measured, and the three methods, matrix matching method and internal standard method were used to measure the concentration of Pt element in the sample solution before and after spiked, and the recovery rate was calculated. The results are shown in Table 2-2.

[0160] Table 2-2 Recovery test results

[0161]

[0162] From the results in Table 2-2, it can be seen that the results of the determination using the matrix matching method and the internal standard method after direct wet digestion before spike addition are lower than the results of the determination by this method; in the results of three groups of spike additions with different concentrations, the recovery rates of the Pt element by the method of the present invention are 100.50%, 98.30% and 99.60%, and the results are all above 95%. The recovery rate results are all higher than the results of the determination using the matrix matching method and the internal standard method after direct wet digestion. Due to the high Al content in the catalyst, there is a certain interference in the determination of the Pt element. Although the matrix matching method and the internal standard method have a certain correction effect on the determination of the Pt element, the accuracy is reduced to a certain extent compared with the results determined after the program digestion treatment using the present concentrated digestion device. Therefore, after the program digestion treatment using the present concentrated digestion device, the aluminum matrix in the sample is effectively removed, and the accuracy of the results is higher.

[0163] (2) Comparative test on the effect of Al-containing matrix and Al-removed matrix on Pt element determination

[0164] The sample treatment method containing Al matrix is ​​to not perform the secondary digestion step of adding HF acid to the alumina-based catalyst sample loaded with Pt element, and other operation steps remain unchanged, to investigate the influence of Al matrix and Al matrix removal on Pt element determination. By adding HF, AlF 3 Precipitation, with AlF 3 The Al matrix was removed in the form of a precipitate to obtain a sample solution with the Al matrix removed (Al content of about 50 μg / mL); in addition, a sample solution containing an aluminum matrix (Al content of about 45 wt%) was obtained by performing the same operation as the method except that HF ​​was not added. The sample solutions obtained by the two pretreatments were measured, and the results are shown in Table 2-3.

[0165] Table 2-3 Determination results of Pt element with Al matrix and without Al matrix

[0166]

[0167] It can be seen from the results in Table 2-3 that by using the concentrated digestion device, the determination result of Pt element in the sample solution without removing the Al matrix is ​​significantly lower than that in the sample solution with the Al matrix removed. This indicates that the secondary digestion with HF in this method to remove the Al matrix can ensure the accuracy of the determination result and eliminate the interference of the matrix to the element determination.

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

[0169] The material obtained by repeatedly washing and drying the filtered material after the above-mentioned catalyst sample loaded with Pt element was subjected to program digestion was scanned by X-ray diffraction spectrum, using an X-ray diffractometer (Malvern Panalytical, the Netherlands, model Sharp Shadow), Cu target, tube current 40mA, tube voltage 45KV, continuous scanning 2θ angle at 5° to 90°, step size 0.01°, such as Fig. 9 The spectrum was analyzed by Highscore software and PDF database, and the result was AlF 3 (PDF 04-023-5575)α-type crystal.

[0170] (4) Scanning electron microscopy analysis test

[0171] The material obtained by repeatedly washing and drying the filtered material after the above-mentioned catalyst sample loaded with Pt element was analyzed by program digestion, and the acceleration voltage was 30kV, the resolution was 0.3nm, the vacuum degree was 270Pa, and the scanning electron microscope analysis results were 2000 times as shown in the figure. Fig.10 As shown, from Fig.10 It can be seen that the crystal is obviously cubic, which verifies the AlF 3 α-type crystals are cubic.

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

[0173] The specific surface area and pore volume of the material obtained by repeatedly washing and drying the filtered material after the above-mentioned catalyst sample loaded with Pt element was processed by program digestion (American Micromeritics Company, model TriStar TM3000) were analyzed. The specific surface area and pore volume were 122.8955m 2 / g, 7.55nm.

[0174] Embodiment 3:

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

[0176] The inert gas external to the reaction container 5 is argon gas with a flow rate of 1.0 L / min and a pressure of 1.5 MPa.

[0177] The cavity structure is a polyhedron, with left and right sides and front and back sides either being symmetrical planes, or diagonal planes being symmetrical, and top and bottom being symmetrical planes, and is composed of 8 inner surfaces.

[0178] Chamber 4 is a closed rectangular industrial resonant cavity. Chamber 4 is made of stainless steel and has a multi-layer anti-corrosion coating. Chamber 4 is equipped with an exhaust system and a cooling system. A centrifugal fan is installed in the chamber with an exhaust volume of 5.0m3 / 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] An observation window is provided on the front door 2, and the mesh of the metal grid or wire mesh of the observation window is 0.1 mm, which effectively prevents microwave leakage.

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

[0181] The reaction container 5 is cylindrical in shape, and has an external interface at the top thereof, which is connected to an external inert gas.

[0182] The material of the reaction container 5 is polytetrafluoroethylene (PTFE), which is permeable and propagable to microwaves.

[0183] 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. The material of the waveguide layer is a non-polar molecular substance, using PEEK fiber, which contains 25% carbon fiber.

[0184] The volume of the reaction container 5 is 1000 mL. The working temperature of the reaction container 5 is 0-350° C. At the highest temperature, the internal pressure can reach 5.0 MPa.

[0185] The microwave frequency of the microwave source of the microwave generating system is 2450MHz, and the microwave output power is 1400W.

[0186] (1) Comparative test of spike recovery

[0187] Using this method, accurately weigh 10.0g (accurate to 0.001g) of alumina-based catalyst sample loaded with Pb element, weigh three parallel samples respectively, add 2.0mg / L, 5.0mg / L and 10.0mg / L of Pb standard substance (taken from 1000mg / L Pb standard solution, commercially available inorganic standard solution) to two of them, use a concentrated digestion device according to the method of the present invention, set the digestion program as shown in Table 3-1, add 20.00mL nitric acid 50% (commercially available, high-grade pure), the temperature is 150℃, the pressure is 1.5Mpa, the time is 50min, perform a primary digestion, add 20.0mL hydrofluoric acid 25% (commercially available, high-grade pure), the temperature is 150℃, the pressure is 1.5Mpa, the time is 75min, perform a secondary digestion, and after the digestion is completed, enter the cooling crystallization program to perform cooling crystallization, the crystallization temperature is 18℃, and the time is 150min. Separate the clear sample solution and solid to be tested, dry and calcine the solid at 105°C and 450°C for 100 min to obtain aluminum fluoride crystals, separate the liquid and transfer it to a 100mL volumetric flask for determination of Pb content. The Pb element series concentration 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.

[0188] Table 3-1 Digestion program settings

[0189]

[0190] In the comparative example, the sample was treated by direct wet digestion method, and then the sample was treated by matrix matching method and internal standard method before determination.

[0191] Direct wet digestion sample processing method. This method has a limited sample processing capacity and cannot achieve large mass weighing. Usually, the mass should be less than 15.0 g. Accurately weigh 10.0 g (accurate to 0.001 g) of alumina-based catalyst sample loaded with Pb element, weigh 3 parallel samples respectively and place them in a quartz crucible, add 20.0 mL of 50% nitric acid (commercially available, high-grade pure), digest on a hot plate at 200°C for 100 min, then add 15.0 mL of 25% hydrofluoric acid (commercially available, high-grade pure), and continue digesting on the hot plate at 180°C for 60 min. After digestion is completed, transfer the digestion solution to a 100 mL volumetric flask to make up the volume for the detection of Pb element content.

[0192] The matrix matching method is that the Pb standard solution used in the determination process should contain a concentration that matches the Al element in the sample. After the direct wet digestion treatment, the aluminum element is not separated and removed, and exists in the sample solution in large quantities, with a concentration of about 45wt%. Therefore, the Pb standard solution is prepared into a matrix containing a concentration of 45wt% Al element for instrument detection. The Pb element series concentration standard solutions used for determination are 0mg / L (blank), 5.0mg / L, 10.0mg / L, 15.0mg / L, 20.0mg / L and 25.0mg / L, respectively, with an Al concentration of 43%. The element concentration value in the sample to be tested should fall within the linear range of the standard working curve.

[0193] The internal standard method is that the Pb standard solution used in the determination process should introduce an internal standard element to eliminate the interference caused by the Al element. In this experiment, Cd is selected as the internal standard element, so the Pb standard solution is prepared to contain the Cd internal standard element standard solution for instrument detection. The Pb element series concentration 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, respectively. The concentration of the internal standard Cd is 10.0 mg / kg, and the element concentration value in the sample to be tested should fall within the linear range of the standard working curve.

[0194] Usually, the amount of spiked test should not be too large, and it is generally appropriate to be 0.5 to 2.0 times the content of the substance to be tested. Under certain working conditions of the inductively coupled plasma emission spectrometer (PerkinElmer, USA, model 5300DV), the samples treated by this digestion method and direct wet digestion were measured, and the three methods, matrix matching method and internal standard method were used to measure the concentration of Pb element in the sample solution before and after spiked, and the recovery rate was calculated. The results are shown in Table 3-2.

[0195] Table 3-2 Recovery test results

[0196]

[0197] It can be seen from the results in Table 3-2 that the results of the determination by the matrix matching method and the internal standard method after direct wet digestion before spike addition are seriously lower than the results of the determination by this method; in the results of three groups of spike additions with different concentrations, the recovery rates of the Pb element by the method of the present invention are 95.50%, 98.20% and 97.70%, and the results are all above 95%. The recovery rate results are much higher than the results of the determination by the matrix matching method and the internal standard method after direct wet digestion. Due to the high Al content in the catalyst, there is a serious interference with the determination of the Pb element. At the same time, the lead element volatilizes greatly during the digestion process, resulting in a low determination result of the direct wet digestion treatment. 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 is difficult to meet in actual determination. Therefore, after the program digestion treatment of the present concentrated digestion device, the aluminum matrix in the sample is effectively removed to ensure the accuracy of the results.

[0198] (2) Comparative test on the effect of Al-containing matrix and Al-removed matrix on Pb element determination

[0199] The sample treatment method containing Al matrix is ​​to not perform the secondary digestion step of adding HF acid to the alumina-based catalyst sample loaded with Pb element, and other operation steps remain unchanged, to investigate the influence of Al matrix and Al matrix removal on the determination of Pb element. By adding HF, AlF 3 Precipitation, with AlF 3 The Al matrix was removed in the form of a precipitate, and a sample solution with the Al matrix removed (Al content of about 44 μg / mL) was obtained; in addition, a sample solution containing an aluminum matrix (Al content of about 45 wt%) was obtained by performing the same test as this method except that HF ​​was not added. The sample solutions obtained by the two pretreatments were measured, and the results are shown in Table 3-3.

[0200] Table 3-3 Determination results of Pb element in Al matrix and Al matrix removed

[0201]

[0202] As can be seen from the results in Table 3-3, by using this concentrated digestion device, the determination result of Pb element in the sample solution without removing Al matrix is ​​significantly lower than that with removing Al matrix, and the presence of high content of Al matrix has a great interference on the determination of Pb element. In this method, HF secondary digestion removes Al matrix, which can ensure the accuracy of the determination result and eliminate the interference caused by the presence of matrix to element determination.

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

[0204] The material obtained by repeatedly washing and drying the filtered material after the above-mentioned catalyst sample loaded with Pb element was subjected to program digestion was scanned by X-ray diffraction spectrum, using an X-ray diffractometer (Malvern Panalytical, the Netherlands, model Sharp Shadow), Cu target, tube current 40mA, tube voltage 45KV, continuous scanning 2θ angle at 5° to 90°, step size 0.01°, such as Fig.11 The spectrum was analyzed by Highscore software and PDF database, and the result was AlF 3 (PDF 04-023-5575)α-type crystal.

[0205] (4) Scanning electron microscopy analysis test

[0206] The material obtained by repeatedly washing and drying the filtered material after the above-mentioned catalyst sample loaded with Pb element was analyzed by program digestion, and the acceleration voltage was 30kV, the resolution was 0.3nm, the vacuum degree was 270Pa, and the scanning electron microscope analysis results were 2000 times as shown in the following figure. Fig.12 As shown, from Fig.12 It can be seen that the crystal is obviously cubic, which verifies the AlF 3 α-type crystals are cubic.

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

[0208] The specific surface area and pore volume of the material obtained by repeatedly washing and drying the filtered material after the above-mentioned catalyst sample loaded with Pb element was processed by program digestion (American Micromeritics Company, model TriStar TM3000) were analyzed. The specific surface area and pore volume were 168.8455m 2 / g, 5.04nm.

[0209] Embodiment 4:

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

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

[0212] The cavity structure is a polyhedron, with left and right sides and front and back sides either being symmetrical planes, or diagonal planes being symmetrical, and top and bottom being symmetrical planes, and is composed of 8 inner surfaces.

[0213] Chamber 4 is a closed rectangular industrial resonant cavity. Chamber 4 is made of stainless steel and has a multi-layer anti-corrosion coating. Chamber 4 is equipped with an exhaust system and a cooling system. A centrifugal fan is installed in the chamber with an exhaust volume of 5.0m3 / 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.

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

[0215] The machine body 1 is designed as two-mode chambers, and the reaction conditions of each chamber can be controlled by a program.

[0216] The reaction container 5 is cylindrical in shape, and has an external interface at the top thereof, which is connected to an external inert gas.

[0217] The material of the reaction container 5 is polytetrafluoroethylene (PTFE), which is permeable and propagable to microwaves.

[0218] 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. The material of the waveguide layer is a non-polar molecular substance, using PEEK fiber, which contains 25% carbon fiber.

[0219] The volume of the reaction container 5 is 450 mL. The working temperature of the reaction container 5 is 0-350° C. At the highest temperature, the internal pressure can reach 5.0 MPa.

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

[0221] (1) Comparative test of spike recovery

[0222] Using this method, accurately weigh 20.0g (accurate to 0.001g) of alumina-based catalyst sample loaded with Co element, weigh three parallel samples respectively, add 20.0mg / L, 40.0mg / L and 60.0mg / L of Co standard substance (taken from 1000mg / L Co standard solution, commercially available inorganic standard solution) to two of them, use a concentrated digestion device according to the method of the present invention, set the digestion program as shown in Table 4-1, add 30.00mL of 28% hydrochloric acid (commercially available 30.00mL of 52% nitric acid (commercially available, high-grade pure) and 30.00mL of nitric acid (commercially available, high-grade pure) were mixed at a temperature of 170°C, a pressure of 3.5Mpa, and a time of 80min for a primary digestion; 30.0mL of 30% hydrofluoric acid (commercially available, high-grade pure) was added at a temperature of 160°C, a pressure of 3.5Mpa, and a time of 100min for a secondary digestion. After the digestion was completed, the cooling crystallization program was entered for cooling crystallization at a temperature of 22°C and a time of 160min. The clarified sample solution and solid to be tested were separated, and the solid was dried and roasted at a drying temperature of 105°C and a roasting temperature of 450°C for 100min to obtain aluminum fluoride crystals. The separated liquid was transferred to a 100mL volumetric flask for constant volume for the detection of Co element content. The concentrations of the Co element standard solutions used in the 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.

[0223] Table 4-1 Digestion program settings

[0224]

[0225] In the comparative example, the sample was treated by direct wet digestion method, and then the sample was treated by matrix matching method and internal standard method before determination.

[0226] Direct wet digestion sample processing method. This method has a limited sample processing capacity and cannot achieve large mass weighing. Usually, the mass should be less than 15.0 g. Accurately weigh 10.0 g (accurate to 0.001 g) of alumina-based catalyst sample loaded with Co element, weigh 3 parallel samples respectively and place them in a quartz crucible, add 10.0 mL of 28% hydrochloric acid (commercially available, high-grade purity) and 10.0 mL of 52% nitric acid (commercially available, high-grade purity) mixed acid, digest on a hot plate at 170° C. for 100 min, then add 20.0 mL of 30% hydrofluoric acid (commercially available, high-grade purity), and continue digesting on the hot plate at 160° C. for 100 min. After digestion is completed, transfer the digestion solution to a 100 mL volumetric flask to make up the volume for the detection of Co element content.

[0227] The matrix matching method is that the Co standard solution used in the determination process should contain a concentration that matches the Al element in the sample. After the direct wet digestion treatment, the aluminum element is not separated and removed, and is present in the sample solution in large quantities, with a concentration of about 45wt%. Therefore, the Co standard solution is prepared into a matrix containing a concentration of 45wt% Al element for instrument detection. The Co element series concentration standard solutions used for determination are 0mg / L (blank), 5.0mg / L, 10.0mg / L, 15.0mg / L, 20.0mg / L and 25.0mg / L, respectively, and the concentration of Al is 45wt%. The element concentration value in the sample to be measured should fall within the linear range of the standard working curve.

[0228] The internal standard method is that the Co standard solution used in the determination process should introduce an internal standard element to eliminate the interference caused by the Al element. In this experiment, Cd is selected as the internal standard element, so the Co standard solution is prepared to contain the Cd internal standard element standard solution for instrument detection. The concentration of the Co element series standard solution used for determination is 0 mg / kg (blank), 5.0 mg / kg, 10.0 mg / kg, 15.0 mg / kg, 20.0 mg / kg and 25.0 mg / kg, the concentration of the internal standard Cd is 10.0 mg / kg, and the element concentration value in the sample to be tested should fall within the linear range of the standard working curve.

[0229] Usually, in the spiked test, the spiked amount should not be too large, and it is generally appropriate to be 0.5 to 2.0 times the content of the substance to be tested. Under certain working conditions of the inductively coupled plasma emission spectrometer (PerkinElmer, USA, model 5300DV), the samples treated by this digestion method and direct wet digestion were measured, and the concentration values ​​of the Co element in the sample solution before and after the spike were measured by this method, matrix matching method and internal standard method. The three methods were used to determine the concentration values ​​of the Co element in the sample solution before and after the spike, and the recovery rate was calculated. The results are shown in Table 4-2.

[0230] Table 4-2 Recovery test results

[0231]

[0232] From the results in Table 4-2, it can be seen that the results of the determination by the matrix matching method and the internal standard method after direct wet digestion before spiking are seriously lower than the results of the determination by this method; in the results of the three groups of different concentrations of spiking, the recovery rate of the Co element of the method of the present invention is 100.20%, 103.40% and 99.70%, and the results are all above 95%. The recovery rate results are higher than the results of the determination by the matrix matching method and the internal standard method after direct wet digestion. Due to the high Al content in the catalyst, there is a certain interference with the determination of the Co element. Although the matrix matching method and the internal standard method theoretically play a certain correction role in the determination of the Co element, it is difficult to meet the accuracy in the actual determination. Therefore, after the program digestion treatment of the present concentrated digestion device, the aluminum matrix in the sample is effectively removed to ensure the accuracy of the results.

[0233] (2) Comparative test on the effect of Al-containing matrix and Al-removed matrix on Co element determination

[0234] The sample treatment method containing Al matrix is ​​to not perform the secondary digestion step of adding HF acid to the alumina-based catalyst sample loaded with Co element, and other operation steps remain unchanged, to investigate the influence of Al matrix and Al matrix removal on the determination of Co element. By adding HF, AlF 3 Precipitation, with AlF 3 The Al matrix was removed in the form of a precipitate, and a sample solution with the Al matrix removed was obtained (the Al content was about 38 μg / mL); in addition, a sample solution containing an aluminum matrix (the Al content was about 45 wt%) was obtained by performing the same operation as the method except that HF ​​was not added. The sample solutions obtained by the two pretreatments were measured, and the results are shown in Table 4-3.

[0235] Table 4-3 Determination results of Co element in Al matrix and Al matrix removed

[0236]

[0237] It can be seen from the results in Table 4-3 that by using this concentrated digestion device, the determination result of Co element in the sample solution without Al matrix is ​​significantly lower than that with Al matrix removed, and the presence of high content of Al matrix interferes with the determination of Co element. In this method, HF secondary digestion removes Al matrix, which can ensure the accuracy of the determination result and eliminate the interference caused by the presence of matrix to element determination.

[0238] Comparative Example 1:

[0239] A comparative test on the influence of using condensation reflux atomizer and not using condensation reflux atomizer on the determination of Pb element in alumina-based catalyst samples loaded with Pb element.

[0240] The use of the condensation reflux atomizer can effectively prevent the volatilization loss of volatile elements during the digestion process. The alumina-based catalyst sample loaded with Pb element was treated with the present concentrated digestion device. The operation process is as described in Example 3. For the comparison column, except for the operation without the condensation reflux atomizer, other operation conditions are also as described in Example 3. The sample solutions obtained by the two pretreatments were measured, and the results are shown in Table 5-1.

[0241] Table 5-1 Comparative measurement results with and without condensation reflux

[0242]

[0243] It can be seen from the results in Table 5-1 that by applying the present concentrated digestion device, the comparison results of using a condensing reflux atomizer and not using a condensing reflux atomizer are obvious. Without using a condensing reflux atomizer, the loss of Pb element is relatively large, while using a condensing reflux atomizer can obviously avoid the loss of Pb element.

[0244] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, technicians familiar with the field may make various corresponding changes and deformations based on the present invention, but these corresponding changes and deformations should all fall within the scope of protection of the claims of the present invention.

Claims

1. A method for separating aluminum fluoride by programmed digestion, It is characterized in that include: A catalyst with aluminum oxide loaded with metal elements as a carrier is placed in a reaction vessel of an agglomerated digestion device, hydrochloric acid and / or nitric acid is added, a digestion program is set, an inert gas is introduced for pre-pressurization, a primary digestion is performed, and a condensation reflux atomizer is turned on at the same time; after the program is completed, hydrofluoric acid is added, a digestion program is set, and a secondary digestion is performed; After the digestion is completed, the cooling crystallization program is entered to perform cooling crystallization, and the clarified sample solution and solid to be tested are separated. The solid is dried and roasted to obtain aluminum fluoride crystals. The sample solution is used for the detection of metal element content; The agglomerative 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 condenser, an atomizer generator, a condenser water inlet and a condenser water outlet, the lower end of the condenser is connected to the reflux pool, and the side of the reflux pool is connected to the atomizer generator through a sealing ring; a condenser lower outlet is provided at the bottom of the condensation reflux atomizer, and the condenser lower outlet is connected to the reaction container; The atomizer generator is a glass concentric atomizer, the center of which is a capillary tube, the capillary tube is parallel to the airflow of the carrier gas, the carrier gas is introduced through an external air inlet instrument port on one side of the body, the airflow quickly passes through the end of the capillary tube, meets the carrier liquid in the atomizer generator at the atomizer nozzle and shears the liquid to form tiny droplets, the tiny droplets are sprayed out with the carrier gas, condensed by the condenser tube to form condensate, the condensate droplets flow back into the reflux pool and into the reaction container; the upper part of the reaction container is provided with an external interface, which is connected to an external inert gas.

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

3. The method according to claim 1, It is characterized in that The content of aluminum oxide in the catalyst is 10wt% to 98wt%, and the particle size of the catalyst after grinding is less than 74μm; the catalyst is dried at 105℃ to 120℃ for 100min to 150min, cooled, and then placed in the reaction container of the agglomerative digestion device.

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

5. The method according to claim 1, It is characterized in that The amount of hydrochloric acid and / or nitric acid added is in the ratio of 5.0 mL to 10.0 mL of acid / 1.0 g of catalyst, the amount of the 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 primary digestion is 120° C. to 200° C., the pressure is less than 5.0 MPa, and the time is 30 min to 120 min.

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

7. The method according to claim 1, It is characterized in that The drying temperature is 105°C to 120°C, the calcination temperature is 450°C to 600°C, and the time is 100min to 200min; the aluminum fluoride crystal is an α-crystalline AlF 3 , with a specific surface area greater than 40m 2 / g, pore size greater than 50 angstroms.

8. The method according to claim 1, It is characterized in that The machine body comprises 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 machine body and is opened or closed by the front door. The chamber structure is a polyhedron, and the left and right sides and the front and rear sides are respectively or all symmetrical planes, or the diagonal planes are symmetrical, and the upper and lower sides are symmetrical planes, and the chamber body is composed of at least 8 inner surfaces; the upper 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 is not a turntable type, but a chassis 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 to an external gas inlet and a gas cylinder.

9. According to the method of claim 1, the carrier gas in the atomizer is an inert 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, which is hydrochloric acid and / or nitric acid, and 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, It is characterized in that The catalyst is digested by the method described in any one of claims 1 to 9 to separate aluminum fluoride, and then the content of each metal element is determined.

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