29 results about "Palladium nitrate" patented technology

The present invention discloses a method for preparing highly dispersible submicron spherical palladium powder. The method comprises the following steps: first, weighing solid palladium nitrate and dissolving it in dilute nitric acid to prepare a dilute palladium nitrate solution; then dissolving a reducing agent in deionized water to obtain a reducing solution; then weighing a dispersant and an additive and dissolving them in deionized water to obtain a mixed base solution; and then mixing the three to obtain a reaction slurry containing palladium powder. The mixture is then filtered, washed, and dried to obtain submicron spherical palladium powder particles. The present invention adopts a liquid phase reduction method to reduce the palladium nitrate solution with ascorbic acid or hydrazine hydrate as a reducing agent to prepare the submicron spherical palladium powder. An organic polymer dispersant and a small molecule alcohol additive are simultaneously added to the base solution in a symmetrical manner. While ensuring the yield of palladium powder, the particle growth process and dispersibility are well controlled. The prepared palladium powder particles are spherical and highly dispersed, with a particle size of 100 to 600 nm.

The invention discloses a high-stability MEMS hydrogen sensor and a preparation method thereof. The high-stability MEMS hydrogen sensor is a semiconductor resistance type hydrogen sensor based on a metal oxide gas sensitive coating and sequentially comprises a silicon nitride supporting layer, a Pt / Ti heating electrode, a sensing electrode, a silicon nitride isolating layer and a metal oxide gas sensitive film from bottom to top. The metal oxides are high-purity antimony doped tin dioxide, tetraamino palladium nitrate and tetraammineplatinum nitrate. The preparation method comprises the following steps: mixing high-purity antimony-doped tin dioxide powder, tetraamino palladium nitrate powder and tetraammineplatinum nitrate powder, preparing gas-sensitive slurry from a mixed solution of terpilenol, diethylene glycol butyl ether acetate, ethyl cellulose, dibutyl phthalate and dioctyl phthalate, dispensing the gas-sensitive slurry on a central interdigital electrode area of an MEMS chip, and performing vacuum drying to obtain the gas-sensitive MEMS chip. And performing vacuum standing and slow heating to obtain the sensor. The sensor is low in detection lower limit and stable in resolution ratio after high-humidity aging.

This invention belongs to the field of hydrogenation catalyst technology, specifically relating to a Pd-Cu bimetallic catalyst, its preparation method, and its application. Using palladium nitrate and copper nitrate as metal sources, 2-methylimidazole as an organic ligand, and SiO2 as a support, a metal-organic framework precursor is constructed via a solvothermal method. This precursor is then subjected to a two-step heat treatment process: N2 atmosphere pyrolysis and air atmosphere calcination, yielding a PdxCu@SiO2 catalyst with an adjustable Pd / Cu molar ratio. The Cu loading is 4.0 wt.%, and the Pd loading is 0.5~5.5 wt.%. This invention features a mild and easily controllable process, allowing for precise optimization of the catalyst's active site structure. The SiO2 support effectively improves the catalyst's dispersibility and stability. The resulting catalyst exhibits excellent performance in CO2 hydrogenation to methanol, with a maximum CO2 conversion rate of 16.3%, a methanol selectivity of 64.5%, and a space-time yield approximately 18.5 times higher than that of the traditional impregnation method, while also demonstrating excellent long-term operational stability.

The application belongs to the technical field of palladium powder material, and particularly relates to a chemical synthesis method of high-dispersion spherical palladium powder, which comprises the following steps: preparing a palladium-containing solution: adding water and a palladium nitrate solution into a container in sequence, adding ammonia water after stirring uniformly, adjusting the pH to 9-10, and preparing the palladium-containing solution A after sufficient stirring; in volume units, water:ammonia water=100:50-100; preparing a reducing agent solution: adding water, a dispersing agent and hydrazine hydrate into the container in sequence, and preparing the solution B after sufficient stirring; in mass-volume units, water:dispersing agent:hydrazine hydrate=100-300:0.1-0.5:20-40; pouring the solution A into the solution B, slowly stirring, cleaning with water and alcohol in sequence after precipitation, drying in an oven, and screening to obtain the palladium powder. The prepared palladium powder is spherical and has good dispersity, and the specific surface area is 1.5-2.5 m 2 / g.

The embodiment of the invention provides a method for preparing palladium nitrate at normal temperature and a preparation system thereof, and relates to the technical field of palladium nitrate preparation methods.The method comprises the steps that S1, aqua regia dissolution-oxidation is conducted to obtain an H2PdCl6 solution, S2, high-valence palladium liquid is subjected to ultrasonic reduction to obtain high-activity palladium powder, and S3, the high-activity palladium powder is obtained. The high-activity palladium powder obtained in the second step is filtered and washed, 0.50%-2% of pH maintaining agent is adopted for washing for 1-2 times, and then deionized water at the temperature of 40-50 DEG C is adopted for washing till the palladium powder is neutral; a certain amount of nitric acid is weighed according to the required concentration of palladium nitrate, then the high-activity palladium powder washed to be neutral in the step S3 is equally divided by weight, and sufficient nitric acid is sequentially and sufficiently stirred and dissolved in a segmented mode. According to the scheme, nitric acid does not need to be additionally added, and the obtained palladium nitrate is high in concentration.

The invention discloses a nano spherical SnPd oxide, which is prepared by the following steps: firstly, cross-linking tannic acid and formaldehyde at room temperature by taking F127 as a surfactant, then adding stannous sulfate and palladium nitrate dihydrate for chelation, carrying out hydrothermal reaction to obtain a SnPd phenolic hybrid, and finally, calcining to obtain the nano spherical SnPd oxide, namely SP for short. SP is an n-type semiconductor, and the chemical composition of SP is SnO2 and Pd; the diameter of the mesoporous nanosphere is 100-150nm, and the average pore size of the mesoporous nanosphere is 5-7nm. The preparation method comprises the following steps: 1, preparing the SnPd phenolic hybrid SPZ; 2, preparation of an SnPd oxide SP; according to the SP-based hydrogen sensor and the preparation method thereof, the response value is 14.6, the response time is 1.5-2 seconds, the recovery time is 7-10 seconds, and the minimum hydrogen concentration detection is 0.2 ppm; the cycling stability reaches 30 days; the catalyst has selectivity on ammonia gas, methane, carbon dioxide, carbon monoxide and nitrogen dioxide.

The invention discloses a preparation method of a high-activity low-load palladium-carbon catalyst for disproportionated rosin. The preparation method comprises the following steps: 1) preparing a carbon carrier; 2) preparing a palladium precursor solution; 3) preparing a reducing agent solution; 4) reduction treatment; and 5) vacuum drying. According to the invention, palladium nitrate is used as a precursor of an active component palladium, activated carbon is used as a carrier, water is used as a solvent, and the catalyst is prepared by combining a deposition-precipitation method and wet reduction. The activity of the prepared catalyst is improved by 1.27 times, meanwhile, the palladium consumption is reduced by 50%, and the consumption of precious metal resources is remarkably reduced. The palladium-carbon catalyst prepared by the method has the characteristics of high dispersity, small particle size and low precious metal palladium consumption, shows remarkable catalytic activity, can be continuously and repeatedly used for more than five times, and has good application prospect and practical value.

The invention discloses a preparation method of a magnetic metal composite nanomaterial. The invention relates to a preparation method of a metal palladium-iron nano material. The preparation method comprises the following steps: adding spherical nano ferroferric oxide powder into a solvent (water, ethanol, acetonitrile, methylbenzene and the like), carrying out ultrasonic reaction for half an hour, adding pentacarbonyl iron (1-10mmol / L) and palladium compounds (0.1-1mmol / L, palladium chloride, palladium nitrate, palladium sulfate, palladium acetate, bis (dibenzylideneacetone) palladium, bis (acetonitrile) palladium dichloride and the like, and the ratio of the amount of substance of the palladium element to the amount of substance of all iron elements is 0.01-0.1), sealing a reaction container, carrying out ultrasonic reaction for half an hour, and cooling to room temperature to obtain the spherical nano ferroferric oxide. Reacting at 80 DEG C for 2 hours, opening the reaction container, cooling to room temperature, and continuously reacting for 2 hours; and centrifuging the obtained reaction liquid to obtain brown solids, washing the brown solids, and carrying out vacuum drying on the obtained black solids to obtain black powder, namely the palladium-iron composite nanomaterial loaded on the spherical ferroferric oxide. The composite material obtained according to the method is good in dispersity and uniform in particle size, and the size is intensively distributed between 2 nm and 3 nm.

The present invention belongs to the technical field of precious metal-supported catalysts, and specifically relates to a preparation method and application of a palladium / amphoteric chelate resin hydrogenation catalyst. The preparation method comprises the following steps: heating and stirring a primary amine resin, a phosphorous acid aqueous solution, and hydrochloric acid, followed by adding formaldehyde and keeping the temperature low to obtain a functionalized resin; purifying the functionalized resin in an ion exchange column, and then washing with water to obtain an amphoteric chelate resin; adding a palladium nitrate solution to the amphoteric chelate resin, stirring, filtering, and washing to obtain an amphoteric chelate resin loaded with palladium ions, and then subjecting the resin to liquid-phase reduction with ascorbic acid and gas-phase reduction with a mixed hydrogen stream to obtain a palladium / amphoteric chelate resin hydrogenation catalyst. The application is to use the prepared hydrogenation catalyst for the hydrogenation of furfuryl alcohol to produce cyclopentanone. The present invention designs a novel preparation method to address the problems of insufficient selectivity, catalytic activity, and long-term structural stability of ion exchange resin-based catalysts obtained by current preparation methods.

The application discloses a kind of mechanical activation method for quickly preparing palladium sulfate and palladium nitrate, belongs to the field of palladium compound product preparation, comprising the following steps: (1) pretreatment: ceramic jar and ceramic ball are used as ball milling container and medium, ceramic ball diameter includes two specifications of 5mm and 10mm, and is mixed according to the mass ratio of 3:1;(2) raw material mixing: palladium powder with purity ≥99.95% and ammonium persulfate are mixed according to the mass ratio of 1: (2.36~2.57);(3) slurry preparation;(4) mechanical activation;(5) post-treatment: after filtering, washing treatment of ball milling product, according to the purification path of target product, palladium sulfate or palladium nitrate is selected.The application replaces heat energy with mechanical energy as reaction driving force by mechanical activation method, and stable and consistent products can be prepared in a short time at room temperature, and nitrogen oxide toxic gas generation is also eliminated.

The invention relates to the technical field of precious metal electroplating, in particular to a preparation method of palladium tetraammine sulfate, which comprises the following steps: palladium powder dissolution: adding palladium powder into concentrated nitric acid, heating to 60-70 DEG C, stirring and dissolving, and filtering to remove insoluble substances to obtain a palladium nitrate solution; preparing a palladium nitrate solid: heating the palladium nitrate solution to 70 DEG C, and concentrating into the palladium nitrate solid under a vacuum condition; preparing tetraamminepalladium nitrate: adding ammonia water into the palladium nitrate solid at normal temperature to react to generate a large amount of white precipitate, and filtering to obtain tetraamminepalladium nitrate; the method comprises the following steps: preparing tetraammine palladium sulfate: adding tetraammine palladium nitrate into a 6-8 mol / L sulfuric acid solution for dissolving, dropwise adding methanol at 90-100 DEG C, decomposing tetraammine palladium nitrate along with nitric acid to gradually generate tetraammine palladium sulfate, and concentrating the system to a solid state to obtain a tetraammine palladium sulfate crude product; purification of palladium tetramine sulfate: adding the palladium tetramine sulfate crude product into deionized water according to the mass ratio of 1: (8-10), stirring and dissolving at normal temperature, adding ammonium sulfate at one time to separate out white precipitate, filtering, transferring to a vacuum oven, and drying to obtain a palladium tetramine sulfate target product.

The invention discloses a preparation method and application of a noble metal-modified nickel-magnesium bifunctional material, and the modification method comprises the following steps: adding a noble metal precursor, namely ruthenium nitrosyl nitrate or palladium nitrate dihydrate, into deionized water, stirring until the mixture is completely dissolved to obtain a noble metal solution, adding a charcoal-based nickel-magnesium bifunctional material into the noble metal solution, stirring, filtering, washing, and drying to obtain the noble metal-modified nickel-magnesium bifunctional material. Transferring the mixed solution into an oil bath pan, and drying while stirring until the moisture is completely evaporated; and transferring the solid substance into a crucible, and roasting under the protection of nitrogen atmosphere to obtain the modified nickel-magnesium bifunctional material. On the basis of the biochar-based nickel-magnesium bifunctional material, precious metal is further introduced for modification to form Ru-Ni-MgO (at) NC with a special structure, so that the anti-poisoning ability of the biochar-based nickel-magnesium bifunctional material in a real smoke environment is greatly enhanced, and the biochar-based nickel-magnesium bifunctional material not only has excellent ICCM performance under an ideal condition, but also has excellent anti-poisoning ability in a real smoke environment. And excellent ICCM performance and long-term stability can be still maintained under the condition of water-containing and oxygen-containing simulated flue gas.

The invention relates to the technical field of gas sensors, and particularly discloses an assembly-pairing-free catalytic combustion sensor and a preparation method thereof. Comprising a detection element, a compensation element and a supporting bracket, wherein the detection element and the compensation element are welded on the same bracket side by side; the detection element is composed of a gamma-Al2O3 carrier loaded with palladium nitrate and a platinum nitrate catalyst (the mass ratio of palladium to platinum is 2: 1-4: 1), and the compensation element is a composite ceramic body without a catalyst and is prepared by mixing seven oxides such as aluminum oxide (65-80%) and silicon dioxide (8-11%) according to a specific proportion. During preparation, the detection element is prepared into slurry through catalyst powder and an ethylene glycol solution, and the slurry is impregnated by a platinum wire coil and electrified to sinter and form; the compensation element is formed by blending slurry with composite oxide powder and an aluminum nitrate solution and adopting the same coil and sintering process. By innovating a compensation element material system and a preparation process, natural matching of initial resistance of the detection element and the compensation element is realized, and a traditional pairing process is thoroughly omitted.

The invention discloses a method for rapidly preparing palladium sulfate and palladium nitrate through a mechanical activation method, and belongs to the field of palladium compound product preparation, and the method comprises the following steps: (1) pretreatment: adopting a ceramic tank and ceramic balls as a ball milling container and a medium, the diameters of the ceramic balls comprise two specifications of 5mm and 10mm, and mixing the ceramic balls according to a mass ratio of 3: 1; (2) raw material mixing: mixing palladium powder with the purity of more than or equal to 99.95% and ammonium persulfate according to the mass ratio of 1: (2.36-2.57); (3) preparing slurry; (4) mechanical activation; and (5) post-treatment: filtering and washing a ball-milled product, and selecting a purification path of palladium sulfate or palladium nitrate according to a target product. According to a mechanical activation method, mechanical energy is used for replacing heat energy to serve as reaction driving force, a product with high stability and high consistency can be prepared at normal temperature within a short time, and meanwhile toxic gas of nitric oxide is completely eradicated.

The application discloses a kind of palladium complex excitation agent, by palladium compound and containing double amine group or hydroxyl compound in nonpolar solvent Complexation reaction is made.Therein, the palladium compound is soluble palladium salt, preferably palladium chloride, palladium nitrate or palladium sulfate;The compound containing double amine group or hydroxyl group includes at least one of catechol or o-phenylenediamine;The nonpolar solvent includes at least one of pyridine or n-hexane;The mass ratio of palladium element in the palladium compound and the compound containing double amine group or hydroxyl group is 1:5-5:1;The reaction temperature of the complexation reaction is 50~110 DEG C, pressure is 0.1~0.3MPa, reaction time is 2~5h.The palladium complex excitation agent prepared by the method of the application can be compounded with negative ion emission functional powder, significantly improve the excitation efficiency of composite material, and can reduce harmful radiation.

This invention belongs to the field of chemical synthesis technology and discloses a lactamide- 13 The preparation method of C includes the following steps: under nitrogen protection, acetaldehyde is added, and K is added. 13 CN, add 1 ml H2O, purge with nitrogen, add 30% sulfuric acid aqueous solution, react to complete, add sodium chloride solid until supersaturated, extract, and evaporate to dryness to obtain a yellow oily liquid; add 2-hydroxypropionitrile-1- 13 C. Add acetic acid, add hexamethylenetetramine, purge with nitrogen, allow the reaction to complete, add palladium nitrate, react for 30 minutes, concentrate, and column chromatography to obtain 2-hydroxypropionamide-1- 13 C. This invention avoids the use of reaction equipment with high airtightness requirements and low-temperature reaction conditions down to -78°C. It directly uses commercially available labeled potassium cyanide as the starting material, and the reaction conditions are mild and easy to implement. Moreover, the two-step reaction yield of this invention is higher than that of the prior art.

The application relates to the field of biological monitoring and particularly belongs to a detection method of chlorogenic acid and application thereof. The method comprises the following steps: taking palladium nitrate, iron nitrate nonahydrate and glutathione as raw materials to prepare FePd2S4 nano-enzyme particles; mixing different concentrations of chlorogenic acid standard solution with acetic acid-sodium acetate buffer solution, H2O2, 3,3',5,5'-tetramethylbenzidine and FePd2S4 nano-enzyme suspension, incubating, measuring the absorbance value at 652 nm, taking the concentration of chlorogenic acid as the abscissa and the absorbance difference as the ordinate, drawing a standard curve and obtaining a linear equation; processing a sample to be measured, extracting chlorogenic acid in the sample to be measured, and preparing a sample solution; taking the sample solution to replace the chlorogenic acid standard solution to repeat the above steps and measure the absorbance value; and calculating the content of chlorogenic acid in the sample to be measured according to the linear equation of S.2. The method has the advantages of simplicity, low cost, high stability, environmental friendliness and the like and is suitable for large-scale preparation.

The invention discloses an SCR (Selective Catalytic Reduction) modified honeycomb catalyst for synergistically removing mercury and nitrate at low temperature and a preparation method of the SCR modified honeycomb catalyst, and belongs to the technical field of catalysts. According to the technical scheme, the modified honeycomb catalyst comprises a porous honeycomb carrier and an active component impregnation liquid, the porous honeycomb carrier is prepared from the following raw materials: amphoteric oxide, rubidium nitrate, polyethylene glycol, sodium carboxymethyl cellulose, triethanolamine, silicon dioxide, aluminum oxide, calcium oxide, quartz fiber, soybean oil and water; the active component impregnation liquid is prepared from the following raw materials in parts by weight: ammonium metavanadate, ammonium metatungstate, ammonium molybdate tetrahydrate, oxalic acid, manganous nitrate, cerous nitrate, palladium nitrate, platinum nitrate, alkylphenol ethoxylates and water. The low-temperature denitration demercuration catalyst has efficient denitration and demercuration synergic performance under the low-temperature condition.

The present application embodiment provides a method for preparing palladium nitrate at room temperature and its preparation system, it is related to the technical field of palladium nitrate preparation method, the method including: step S1, aqua regia dissolution-oxidation to obtain H2PdCl6 solution, step S2, ultrasonic reduction of high-valent state palladium liquid to obtain high-activity palladium powder, step S3, buffer washing: the high-activity palladium powder obtained by step S2 is filtered and washed, 1-2 times are washed with a pH maintenance agent of 0.50%-2%, and then washed to neutrality with deionized water of 40°C-50°C; step S4, normal temperature peracid segmented dissolution of palladium powder: a certain amount of nitric acid is weighed according to the concentration required for palladium nitrate, and step S3 is then washed to neutral high-activity palladium powder by weight, and sufficient nitric acid is segmented and fully stirred for dissolution. This program does not need to add nitric acid separately, and the palladium nitrate concentration obtained is higher.

The invention provides a preparation method of silver-palladium alloy powder, and belongs to the field of precious metal alloy powder material preparation. The invention provides a preparation method of silver-palladium alloy powder, which comprises the following steps: mixing a reducing agent, a lubricating agent, a palladium nitrate solution, silver nitrate and water for reduction reaction to obtain the silver-palladium alloy powder, the lubricant is a stearic acid lubricant; the reducing agent is ascorbic acid. According to the preparation method, the lubricant is used for replacing a traditional surfactant to serve as a dispersing agent in reaction to prepare the powder, and the variety of the reducing agent is adjusted, so that the obtained powder has monodispersity, particles are spherical, smooth in surface, narrow in particle size distribution and high in alloying degree, and the powder particles are extremely easy to settle and convenient to wash and separate; therefore, the production process is simple, low in cost, short in period and suitable for mass production.

The invention relates to a method for detecting aflatoxin B1 in edible oil. The method comprises the following steps: 1) preparing PdO nano-enzyme particles by taking palladium nitrate as a raw material; 2) drawing an aflatoxin B1 standard curve and obtaining a linear equation; (3) extracting aflatoxin B1 in to-be-detected edible oil, and preparing to-be-detected liquid; 4) replacing the aflatoxin B1 standard solution with the to-be-measured solution, and measuring the absorbance value of the to-be-measured solution at 652 nm; and 5) substituting the absorbance value into a linear equation, and calculating the concentration of aflatoxin B1 brought into the edible oil to be detected. According to the detection method, the aflatoxin B1 in the edible oil can be rapidly and efficiently detected, and meanwhile, the preparation method of the palladium oxide nano-enzyme particles is simple, low in cost, high in stability, environmentally friendly and suitable for large-scale preparation. In the detection process, the dosage of the required nano enzyme is small, the detection sensitivity is high, the response time is short, and the detection time is greatly shortened.

The invention relates to a potassium tetracyanopalladate synthesis method, which comprises: S1, acid dissolution oxidation: carrying out a dissolution reaction on a metal palladium powder raw material to generate a palladium nitrate-containing aqueous phase solution; s2, precipitation: carrying out precipitation reaction on the aqueous phase solution containing palladium nitrate prepared in the step S1 to generate a palladium cyanide solid intermediate; s3, washing: washing the palladium cyanide solid intermediate generated in the step S2 to remove impurity ions; and S4, reactive crystallization: reacting the palladium cyanide intermediate purified in the step S3 with potassium cyanide, and crystallizing to obtain a potassium tetracyanopalladate product. According to the method, synthesis of potassium tetracyanopalladate can be achieved through a simple and rapid method, and the obtained product is high in purity, uniform in crystal form, good in solubility and suitable for application scenes with high requirements for plating quality in the industries of semiconductors, PCBs, aerospace and the like; the potassium tetracyanopalladate is used as a key raw material of a palladium plating process and is used in the field with high requirements on material performance and appearance.

The invention discloses a PdGa / alpha-MoC bimetallic catalyst as well as a preparation method and application thereof. Respectively dissolving ammonium molybdate, gallium nitrate and palladium nitrate in water, mixing, drying and calcining to obtain a PdGa / MoO3 precursor, and further carbonizing and passivating to obtain the PdGa / alpha-MoC bimetallic catalyst. The prepared PdGa / alpha-MoC catalyst takes noble metal and transition metal as active components, and high dispersion of metal species is realized through high migration ability of molybdenum atoms on a carbide carrier. Wherein the doping of Ga enables the catalyst to have richer oxygen vacancies and acid sites, and the active sites significantly enhance the adsorption and conversion of reactants on the surface of the catalyst. The synergistic combination of bimetallic loading and oxygen vacancy regulation realizes efficient and selective hydrodeoxygenation of vanillin, keeps stable hydrodeoxygenation activity in the whole cycle test, and has good application prospects.

This invention relates to a method for preparing a carbon-supported core-shell platinum-nickel catalyst for proton exchange membrane fuel cells. The method involves thoroughly impregnating a carbon support with nickel salt and palladium nitrate, adjusting the pH of the impregnation solution with sodium hydroxide to obtain a precursor solution for preparing the nickel core, transferring it to a reactor, heating it to 120-180°C, and introducing hydrogen gas for a first pressurized hydrogen reduction to obtain carbon-supported nickel nanoparticles. Subsequently, the carbon-supported nickel nanoparticles are mixed with a platinum nitrate solution, and the solution pH is adjusted with ammonia water for a second impregnation and ultrasonic stirring. The mixture is then transferred to a reactor, heated to 40-90°C, and introduced hydrogen gas for a second pressurized hydrogen reduction to obtain the carbon-supported core-shell platinum-nickel catalyst product. The mass activity of the core-shell platinum-nickel catalyst prepared by this invention exceeds 0.70 A·mg. Pt ‑1 It is superior to the 0.25 A·mg of mainstream platinum-carbon catalysts currently on the market. Pt ‑1 .

The application relates to the technical field of gas sensors, and particularly discloses a catalytic combustion sensor free of assembly pairing and a preparation method thereof; the catalytic combustion sensor comprises a detection element, a compensation element and a supporting bracket, the detection element and the compensation element are welded side by side on the same bracket; the detection element is composed of a gamma-Al2O3 carrier loaded with a palladium nitrate and platinum nitrate catalyst (the mass ratio of palladium to platinum is 2:1-4:1), and the compensation element is a composite ceramic body without catalyst, which is made of seven oxides such as alumina (65-80%) and silicon dioxide (8-11%) mixed in a specific ratio. During preparation, the detection element is formed by slurry prepared by mixing catalyst powder and ethylene glycol solution, platinum gold wire coil immersion and electric sintering; the compensation element is formed by slurry prepared by mixing composite oxide powder and aluminum nitrate solution, and the same coil and sintering process are adopted. The application realizes the natural matching of the initial resistances of the detection element and the compensation element by innovating the material system and the preparation process of the compensation element, and the traditional pairing process is completely saved.

The invention discloses a synthesis method of flonicamid intermediate 4-trifluoromethyl nicotinic acid, and belongs to the technical field of synthesis of 4-trifluoromethyl nicotinic acid. 2, 6-dichloro-3-cyano-4-trifluoromethylpyridine is subjected to catalytic hydrogenation under catalysis of bimetallic catalyst particles, and 2, 6-dichloro-3-cyano-4-trifluoromethylpyridine is subjected to post-treatment to obtain the flonicamid intermediate 4-trifluoromethyl nicotinic acid. The intermediate product 3-cyano-4-trifluoromethylpyridine is subjected to a cyano hydrolysis reaction in a sodium hydroxide ethanol solution, and the target product 4-trifluoromethyl nicotinic acid is obtained through acidification and purification. According to the preparation method, ferrous sulfate heptahydrate is taken as an iron source, terephthalic acid is taken as an organic ligand, an iron metal organic framework is loaded on the surface of a matrix, then palladium nitrate is taken as a palladium source, bimetallic catalyst particles loaded with zero-valent iron and metal palladium are prepared through heating reduction, and the organic ligand can play a role in supporting a porous structure after carbon formation; according to the method, the capture of the nano zero-valent iron on chlorine is improved, and poisoning of a palladium catalyst is slowed down, so that the service life of the bimetallic catalyst is prolonged, and continuous production of 4-trifluoromethyl nicotinic acid is facilitated.

The invention relates to a preparation method of a palladium oxide solid material, which comprises the following steps: dissolving palladium nitrate in nitric acid to obtain a palladium nitrate-nitric acid solution, mixing the palladium nitrate-nitric acid solution with fused salt, calcining at high temperature, adding water into a reaction product, ultrasonically dissolving, centrifugally filtering and drying to obtain the palladium oxide solid material. Compared with the prior art, a high-temperature molten salt method is used, and toxic chlorine and a complex technological process are avoided. The method comprises the following steps: firstly, directly converting palladium nitrate into a palladium oxide solid by using a high-temperature molten salt method, then removing molten salt through ultrasonic washing, and finally, carrying out centrifugal filtration and drying to obtain a pure palladium oxide solid.

The invention discloses a method for converting sugar into 2, 5-hexanedione by monatomic catalysis, which comprises the following steps: taking glucose as a raw material, and reacting under the synergistic catalysis of a monatomic catalyst Pd-N-C and an auxiliary agent to prepare 2, 5-hexanedione; during the reaction, the hydrogen pressure is 1-2MPa, the reaction temperature is 120-160 DEG C, and the reaction time is 15-60 minutes; the preparation method of the monatomic catalyst Pd-N-C comprises the following steps: mixing palladium nitrate, phenanthroline and absolute ethyl alcohol to react; and heating to 300-700 DEG C at a heating rate of 2 DEG C / min in an N2 atmosphere, calcining for 1-2 hours, naturally cooling, carrying out acid etching for 6-8 hours in a water bath of 60-80 DEG C by using a 0.5 M H2SO4 solution, and carrying out suction filtration, washing and drying to obtain the monatomic catalyst Pd-N-C, and the auxiliary agent is AlCl3 and / or SnCl4. According to the method, the reaction conditions are effectively reduced, and the selectivity of the 2, 5-hexanedione is improved.

The present invention addresses the problem of providing a method for efficiently recovering palladium from a palladium-containing material. [Solution] A method for recovering palladium from a palladium-containing material, comprising: a step of dissolving the palladium-containing material in a nitric acid-containing solution to obtain a palladium nitrate solution; a step of passing the palladium nitrate solution through a resin to adsorb palladium onto the resin; and a step of calcining the resin with the adsorbed palladium to recover palladium, wherein acidic gases remaining in the resin layer during the step of passing the solution are vented.