663 results about "Palladium" patented technology

The invention provides a method and system for detecting the content of platinum, palladium and rhodium in an automobile exhaust purification catalyst and application, and relates to the technical field of automobile exhaust purification, the method comprises the following steps: crushing, grinding, sieving, performing microwave acidolysis, neutralizing, washing and drying a catalyst sample to obtain dry filter residues; a trapping agent and a fluxing agent are added into the dry filter residues, constant-temperature heating is conducted in inert gas, then cooling forming is conducted, and an alloy button is obtained; blowing ash on the alloy, then adding mixed acid into the alloy, heating the alloy in a water bath at 95 DEG C for 25-35 minutes to obtain a dissolved solution, then adding a masking agent into the dissolved solution, and oscillating to obtain a solution to be detected; and filtering the liquid to be detected, fixing the volume and detecting. According to the method, precise quantification of trace platinum, palladium and rhodium in the complex matrix catalyst can be realized, and the method has a relatively high recovery rate; meanwhile, pollution elements are prevented from being used, and the method is green and efficient and better conforms to the concept of green chemistry.

The invention relates to the technical field of precious metal recovery, in particular to a process for separating precious metal from copper-nickel smelting waste, which comprises the following steps: crushing and grading the waste, adding a sulfuric acid solution containing etidronic acid, leaching, and washing, drying and crushing filter residues to obtain a pretreated material; mixing the pretreated material with a sodium peroxide-sodium carbonate composite flux, roasting, leaching with water, and filtering to obtain a filter residue B; adding a leaching agent containing hydrochloric acid, sodium chlorate and 1, 2-cyclohexanediamine tetraacetic acid into the filter residue B according to the ratio of 1: 3-1: 5, and filtering to obtain filtrate C and filter residue C; adjusting the pH value of the filtrate C to 1.5-2.5, adding an ethanol solution of sodium N, N-diethyldithiocarbamate, precipitating, washing and calcining to obtain sponge palladium; adding ammonium chloride into the filtrate D, precipitating and calcining to obtain sponge platinum; and leaching the filter residue C by using a hydrochloric acid-chloroauric acid mixed solution containing diphenylthiourea, and replacing and calcining zinc powder to obtain crude gold. According to the process, the leaching rates of platinum, palladium and gold and the product purity are greatly improved; flux and reagent systems are optimized, consumption and energy consumption are reduced, waste liquid treatment is matched for up-to-standard discharge, and efficient resource recovery and environment-friendly cooperation are achieved.

The invention discloses a comprehensive treatment method of platinum and palladium slag, and relates to the technical field of non-ferrous metal metallurgy. After the platinum and palladium slag is subjected to sulfating roasting, flue gas is introduced into a selenium absorption tower; hydrolyzing the roasting slag, reducing the dissolving solution to recover tellurium, and enabling the dissolving solution to enter a copper recovery process after tellurium precipitation; the dissolving slag is subjected to chlorination dissolution gold separation, and the gold separation slag is subjected to silver recovery; the gold separation liquid is reduced to obtain gold powder; carrying out platinum and palladium precipitation on the gold reduced solution, adding ammonia water into platinum and palladium precipitation to carry out platinum and palladium separation, respectively refining the separated platinum and palladium, and recovering platinum and palladium; carrying out platinum-palladium reduction on the platinum-palladium precipitation post-solution to obtain platinum-palladium precipitation slag and a platinum-palladium reduction post-solution, and returning the platinum-palladium precipitation slag to the roasting process; and performing tellurium reduction on the platinum-palladium reduced liquid to obtain tellurium powder and tellurium reduced liquid, and enabling the tellurium reduced liquid to enter a wastewater treatment process. The method has the beneficial effects that selenium, tellurium, copper, gold, silver, platinum and palladium are separated and recycled step by step, the recycling rate is high, the wastewater treatment difficulty is small, and environmental pollution is reduced.

To provide a calcined body that is processed easier than a conventional calcined body and where differences in hardness between production lots are suppressed.SOLUTION: A calcined body comprises: at least one first transition metal element selected from the group consisting of manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), molybdenum (Mo), technetium (Tc), ruthenium (Ru), rhodium (Rh), palladium (Pd), and silver (Ag); a coloring element of at least one of a lanthanoid rare earth element and a second transition metal element different in kind from the first transition metal element; and zirconia containing a stabilizing element. A content of the first transition metal element is 100 mass.ppm or more, a content of the second transition metal element is less than 100 mass.ppm, and an absolute value of a difference in hardness relative to a hardness of a calcined body obtained from a commercially available powder is 10 HV or less.SELECTED DRAWING: None

A method may include operating a dehydrogenation process whereby a hydrocarbon-containing feed is converted to light olefins, wherein the dehydrogenation process utilizes a fluidized process catalyst that circulates between a reactor and a combustor. The method may comprise withdrawing the process catalyst from the dehydrogenation process, modifying the process catalyst to form a modified catalyst, and adding the modified catalyst back to the dehydrogenation process. The process catalyst may include from 0.1 wt. % to 10 wt. % of one or more metals chosen from gallium, indium, thallium, or combinations thereof, from 1 ppmw to 1000 ppmw of one or more metals chosen from platinum, palladium, rhodium, iridium, ruthenium, osmium, or combinations thereof, and at least 85 wt. % support. Modifying the process catalyst may include adding one or more of manganese, iron, chromium, or vanadium.

The invention discloses a method for recovering platinum and palladium from high-cobalt nickel-containing carbonylation slag, and relates to the technical field of non-ferrous metal carbonylation metallurgy, the method comprises the following steps: S1, hydrogen reduction and activation; s2, feeding into a high-pressure carbonylation reactor; and S3, efficient carbonylation. According to the method, the carbonylation slag is subjected to hydrogen reduction activation treatment, nickel protoxide and cobalt oxide are changed into simple substance nickel, the simple substance nickel is fed into a carbonylation reactor for carbonylation under the protection of reducing gas or inert gas after activation treatment, 95% of Ni, 85% of Fe and 80% of Co are carbonylated to enter a gas phase after carbonylation, bonding of cobalt and a platinum solid solution is broken through carbonylation, and the nickel-cobalt-cobalt-cobalt-cobalt alloy is obtained. Nickel protoxide is difficult to dissolve in various strong acids and oxidizing acids, and a foundation is laid for further separation of base metals and non-metallic element sulfur from precious metals to produce high-grade platinum concentrate.

The invention discloses a hydrogen energy fuel cell catalyst carrier based on a graphene graft polymer, which is characterized in that two-dimensional graphene is used as a substrate, the surface of the two-dimensional graphene is modified with an oxygen-containing functional group, and a functional polymer branch chain containing nitrogen, sulfur or phosphorus heteroatoms is covalently grafted to form a local three-dimensional network winding structure; the carrier is loaded with platinum, palladium, ruthenium and other metal or alloy nanoparticles, the particle size is 2-8 nm, the loading capacity is 10%-40%, and the particles are anchored to polymer functional sites or reduced in situ to a graphene defect area through coordination. A polymer branch chain has pH responsiveness and can adjust the local proton transmission efficiency; the grafting density is 3-15 grafting points per 100 carbon atoms, so that high dispersion and stable anchoring of metal particles are effectively realized; the specific surface area of the carrier is 400-800m < 2 > / g, the electrochemical active area is not less than 80m < 2 > / g, and the activity retention rate is greater than 80% after 5000 circles of accelerated durability tests. The activity, the stability and the proton conduction performance of the catalyst are remarkably improved, and the catalyst is suitable for high-performance fuel cells.

The invention provides a method for recovering platinum group metal from a waste automobile exhaust purification catalyst, and belongs to the field of precious metal recovery. The method comprises the following steps: carrying out crushing and impurity removal pretreatment on the waste catalyst to obtain solid residues; mixing the obtained solid slag with alkali liquor, and performing hot-pressing activation to obtain active slag; leaching the active slag by using an acid leaching system of hydrochloric acid-hydrogen peroxide-sodium chloride to obtain a leaching solution enriched with platinum group metals; adjusting the acidity of the leachate, adding a first adsorption material, selectively adsorbing platinum and palladium, and separating supernate and a platinum / palladium enrichment material; adjusting the acidity of the supernate, adding a second adsorption material, selectively adsorbing rhodium, carrying out solid-liquid separation, and collecting a rhodium enrichment material; respectively eluting and refining the platinum / palladium enrichment material and the rhodium enrichment material, and recovering platinum, palladium and rhodium; through the optimally designed recovery method of alkaline hot-pressing activation-mild acidic directional leaching-two-stage magnetic adsorption separation, efficient recovery of platinum, palladium and rhodium in the waste automobile exhaust catalyst is realized.

The invention discloses a catalyst for dealkylation in a chlorine-containing environment as well as a preparation method and application of the catalyst, and belongs to the technical field of catalyst reaction. The catalyst comprises a carrier and an active component, wherein the carrier comprises ZrO2 and MgFeO4; the active component comprises an auxiliary agent and a noble metal component, the auxiliary agent comprises a V2O5-WO3 composite oxide and a CeO2-MnO2 composite oxide, and the noble metal component comprises at least three of rhodium, ruthenium, platinum, palladium and gold. The noble metal components grow in mesopores of the carrier in a confined manner, and the auxiliaries with dechlorination and catalytic oxidation functions are uniformly distributed on the surface of the carrier, so that a two-step catalytic strategy of dechlorination and oxidation of chlorine-containing waste gas is realized, the poisoning phenomenon of the catalyst is effectively avoided, and an excellent catalytic effect is formed. Moreover, the catalyst is stable in property, still keeps an excellent catalytic function after being used for a long time, and is higher in practicability and better in economical efficiency.

According to the microwave reactor and method for recycling the three-way catalytic precious metal, through the synergistic effect of microwave radiation and the telescopic glass stirring rod, the problem that the mass transfer efficiency is low due to high viscosity of a traditional ionic liquid leaching system is solved, the precious metal leaching time is shortened, and the efficiency is improved. Meanwhile, a diamond ATR crystal infrared probe is adopted to monitor components of a reaction solution in real time, multi-parameter linkage control of microwave power, temperature and stirring rate is combined, reaction conditions are dynamically optimized, and the recovery rate of platinum, palladium and rhodium is increased. The method systematically solves the technical bottlenecks of high energy consumption, heavy pollution and low ionic liquid leaching efficiency of the traditional pyrogenic process / wet process, and provides an innovative scheme with high efficiency, low environmental load and industrial feasibility for precious metal recovery.

The invention discloses a palladium-doped Ir-Sn oxide titanium anode with high catalytic activity and a preparation method of the palladium-doped Ir-Sn oxide titanium anode, and belongs to the technical field of electrolytic anodes. The anode comprises a titanium substrate, a TiO2-Ta2O5 intermediate layer and an Ir-Sn-Pd oxide catalyst layer, the molar ratio of Ir to Sn to Pd in the catalyst layer is (5-6): 3: (1-2), and the total metal ion concentration is 0.3 mol L. The preparation method is realized through titanium substrate pretreatment (sand blasting and etching), intermediate layer coating sintering (a TiCl4-TaCl5 solution) and catalyst layer circulating coating sintering (an H2IrCl6-SnCl4-PdCl2 mixed solution). The relatively cheap palladium element is introduced, the electron structure of the catalyst layer is optimized by utilizing the defect effect, the charge transfer resistance is reduced to 6.7 omegacm, and meanwhile, the iridium consumption is reduced by more than 30%. Experiments show that the cell voltage of the anode is stabilized at 0.95 V (the current density is 5Acm <-2 >), the accelerated life reaches 1630 hours, the coating binding force is 62N, and the corrosion rate in an acidic electrolyte is only 0.01 mm / year. Compared with a traditional iridium tantalum anode, the cost is reduced by 40%, and the overpotential in the oxygen evolution reaction is as low as 0.45 V.

The invention relates to the technical field of CO oxidation, in particular to a CO oxidation catalyst, a preparation method of the CO oxidation catalyst and a CO oxidation method. The carrier is selected from one or more of dysprosium oxide, yttrium oxide and holmium oxide, the particle size of the carrier is 20-100 nm, and the average particle size is 25-76 nm; the noble metal is selected from one or more of platinum, ruthenium and palladium, and the content of the noble metal element is 0.1 wt%-2wt% of the carrier. One or more of dysprosium oxide, yttrium oxide and holmium oxide with the particle size of 20-100 nm and the average particle size of 25-76 nm are adopted as the carrier to prepare the CO oxidation catalyst, and the CO oxidation catalyst is used for CO catalytic oxidation, has the advantage of lower carbon monoxide ignition temperature and is long in service life.

The embodiment of the invention discloses a bifunctional catalyst for direct synthesis and catalytic oxidation of hydrogen peroxide and a preparation method of the bifunctional catalyst. The catalyst with the dual functions is provided with Pd-based alloy nanoparticles and high-dispersion monatomic transition metal sites at the same time. The preparation method comprises the following steps: preparing a zeolite-like molecular sieve carrier taking transition metal as link ions through a rolling hydrothermal method; then loading gold and palladium metals on the zeolite-like molecular sieve carrier by adopting a low-temperature liquid phase reduction method to obtain a bifunctional catalyst; the bifunctional catalyst for direct synthesis of hydrogen peroxide and preparation of methanol through methane oxidation has high methane conversion rate, methanol selectivity and yield.

The invention belongs to the technical field of photocatalysts, and particularly relates to a palladium-loaded bismuth-based heterojunction photocatalyst as well as a preparation method and application thereof. The palladium-loaded bismuth-based heterojunction photocatalyst provided by the invention comprises Pd nano-particle active sites and a heterojunction structure formed by CuBi2O4 and a BiOBr nanosheet, wherein the Pd nano-particle active sites and the CuBi2O4 and BiOBr nano-sheets are arranged in the heterojunction structure; the active sites of the Pd nanoparticles are loaded on the BiOBr nanosheets to form Pd-BiOBr; the Pd-BiOBr is loaded on the surface of the CuBi2O4; and the CuBi2O4 is in a rod-shaped array. The catalyst is applied to photocatalysis of CO2RR, and the selectivity and the yield of a C2 product can be improved.

A method may include contacting a hydrocarbon-containing feed with a catalyst in a reactor to form an olefin-containing effluent, then at least partially separating the olefin-containing effluent from the catalyst. Passing the catalyst to a combustor and heating the catalyst by combusting a supplemental fuel. The supplemental fuel includes methane in an amount greater than or equal to 1 mol. %. Passing the catalyst from the combustor to the reactor, such that at least a portion of the catalyst continuously cycles between the reactor and the combustor. The catalyst includes from 0.1 wt. % to 10 wt. % of one or more metals chosen from gallium, indium, thallium or combinations thereof, from 5 ppmw to 1000 ppmw of one or more metals chosen from platinum, palladium, rhodium, iridium, ruthenium, osmium, or combinations thereof, from 100 ppmw to 30000 ppmw of chromium, and at least 85 wt. % support.

The invention provides a composite hydrogen transfer catalyst based on an MOFs material as well as a preparation method and application of the composite hydrogen transfer catalyst. The composite hydrogen transfer catalyst comprises the MOFs material loaded with an active metal component and solid alkali, the active metal component is selected from at least one of palladium, platinum, ruthenium, rhodium and nickel; the active metal component accounts for 0.5-5% of the mass of the catalyst; the MOFs material is selected from at least one of ZIF-8, MIL-101, UiO-66, HKUST-1 and MOF-5 (Metal Organic Frameworks); the solid alkali is selected from at least one of magnesium oxide, calcium oxide, hydroxyapatite and barium oxide. The catalyst provided by the invention has the advantages of high catalytic activity, good selectivity, strong stability, reusability and the like, can efficiently catalyze fatty alcohol to perform hydrogen transfer reaction under a lower-temperature reaction condition to prepare Guerbet alcohol, remarkably improves the yield and purity of a product, and reduces the reaction energy consumption and cost.

In embodiments herein, a surface finish (SF) is formed on conductive contacts of a package substrate for connection to an embedded interconnect bridge circuitry die. In some embodiments, the SF may be electroless nickel-electroless palladium-immersion gold (ENEPIG). In other embodiments, the SF may be immersion gold-electroless palladium-immersion gold (IGEPIG). In other embodiments, the SF may include a layer of electrolytic palladium-gold on a layer of indium or on a layer of cobalt-iron.

A grease composition that includes at least an oil-based medium, a thickener, and a fullerene-like nano-structure. The fullerene-like nano-structure includes a plurality of layers each comprised of a metal chalcogenide composition has a molecular formula of MX2, where M is a metallic element selected from the group consisting of titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), zirconium (Zr), niobium (Nb), molybdenum (Mo), technetium (Tc), ruthenium (Ru), rhodium (Rh), palladium (Pd), silver (Ag), cadmium (Cd), hafnium (Hf), tantalum (Ta), tungsten (W), rhenium (Re), osmium (Os), iridium (Ir), platinum (Pt), gold (Au), mercury (Hg) and combinations thereof, and X is a chalcogen element selected from the group consisting of sulfur (S), selenium (Se), tellurium (Te), oxygen (O) and combinations thereof.

A hydrometallurgical process for recovering a plurality of metals from a complex rare and precious material, comprising the following steps: step 1: adding a complex rare and precious material to a hydrochloric acid solution, adding an oxidant for reaction, and then performing filtration to obtain a chlorination liquid and a chlorination residue; step 2: using two-stage counter-current gold loading to obtain a gold-loaded liquid and a post-loading liquid, reducing the gold-loaded liquid, performing clarification to obtain an organic phase, and filtering a precipitate to separate a post-reduction liquid and sponge gold; performing evaporation and concentration on the post-reduction liquid to produce a concentrate 1 and a condensate; and cooling and crystallizing the concentrate, performing filtration to obtain residual oxalic acid, and returning the residual oxalic acid to the reduction process and a post-crystallization liquid to gold loading; step 3: performing low-temperature distillation on the post-loading liquid to obtain a concentrate 2; step 4: performing high-temperature distillation on the concentrate 2 to obtain a concentrate 3; step 5: performing directional crystallization and centrifugal filtration on the concentrate 3 to obtain a crystallization residue and selenous acid; and step 6: washing the crystallization residue by using cold water or a low-acid-level condensate produced in step 3, and performing filtration to obtain a tellurium residue and a palladium-platinum-rhodium-rich liquid.

The invention discloses low-activity sintering-resistant silver powder and a preparation method thereof, and belongs to the technical field of precious metal powder materials. The preparation method comprises the following steps: S1, dissolving a reducing agent and a dispersing agent in water, adding a silver nitrate solution, and reacting to obtain a seed crystal solution; s2, adding the seed crystal solution into a dispersing agent solution, and adding a silver nitrate solution and a reducing agent solution at the same time to obtain a reaction mixture; and S3, the reaction mixture is subjected to impurity removal, drying, crushing and sieving, and the low-activity sintering-resistant silver powder is obtained. The prepared silver powder is large in particle size, high in tap density, small in specific surface area and low in burning loss, and is mainly applied to silver-palladium resistance paste or silver-palladium-platinum resistance paste of a thick film heating module.

A catalyst suitable for dehydrogenation of hydrocarbons may include from 0.0005 wt.% to 0.1 wt.% of platinum, palladium, rhodium, iridium, ruthenium, osmium, or combinations thereof; from 0.1 wt.% to 10 wt.% of gallium, indium, thallium, or combinations thereof; from 0.1 wt.% to 5 wt.% of lanthanum, yttrium, or zirconium; at least 85 wt.% support, and from 0 wt.% to 0.001 wt.% cerium.

Provided are: a hydrogen separation filter which has a high hydrogen permeation rate and which prevents or reduces separation between layers; and a method for producing the hydrogen separation filter. The hydrogen separation filter includes a porous substrate and a palladium layer provided on the porous substrate. The grain boundary number density observed in a cross-sectional secondary electron image of the palladium layer is 1-5 grains / [mu] m. A method for manufacturing a hydrogen separation filter includes forming a palladium layer on a porous base material by a sputtering method while keeping the temperature of the porous base material at 300-600 DEG C.

A process for producing amines by reductive amination, the process includes introducing a feed stream, the feed stream comprising an amino alcohol and a reducing agent, and hydrogen in a reaction zone of a reactor, and contacting the feed stream with a catalyst in the reaction zone. A hydrogen flow rate into the reaction zone is adjusted, and a product stream comprising ethyleneamines is extracted. The catalyst includes a carrier component selected from alumina, silica, and combinations thereof; and an active component having a first metal, a second metal, and a third metal. The first metal is selected from cobalt, nickel, and copper, the second metal is selected from rhenium, ruthenium, chromium, zinc, sodium, calcium, magnesium, strontium, lithium, potassium, barium, cesium, lanthanum, tungsten, iron, silver, titanium, manganese, aluminum, rhodium, platinum, palladium, iridium, and combinations thereof, and the third metal is niobium.

The invention provides a catalyst for preparing methanol through carbon dioxide hydrogenation as well as a preparation method and application of the catalyst, and relates to the technical field of catalysts. The catalyst comprises a metal oxide solid solution and a palladium element doped in the metal oxide solid solution; wherein the metal oxide solid solution comprises a zinc oxide-tungsten oxide compound. The catalyst provided by the invention is prepared by hydrothermal crystallization, has the characteristics of high activity, high methanol selectivity and long-time stable operation at relatively high temperature and pressure, and provides a wide prospect for subsequent industrial application and a subsequent conversion process of coupled methanol.

The invention discloses an enzyme-bimetal monatomic composite catalyst as well as a preparation method and application thereof, and belongs to the technical field of biology. The technical problem to be solved is to improve the detoxification effect on mycotoxins (AFB1, ZEN, T-2, DON and OTA). According to the technical scheme, the enzyme-bimetal monatomic composite catalyst is characterized by comprising a framework, bimetal and enzyme, the sum of the loading capacities of the double metals on the catalyst is 0.1-5 wt%, and the loading capacity of the enzyme on the catalyst is 0.1-0.4 mg / mg; and the bimetals are two of palladium, gold, silver, ruthenium, platinum, iron, zinc and zirconium.

The invention relates to an amino silane coupling agent modified halloysite nanotube mercury-free catalyst for acetylene hydrochlorination reaction. The catalyst comprises a carrier and an active component. The carrier is a halloysite nanotube modified by one or more amino silane coupling agents. The active component is one or a combination of more of halides and complexes of precious metals such as gold, silver, rhodium, palladium, platinum and ruthenium, and the mass ratio of the single active component to the carrier is 0.01-1%. The preparation method of the catalyst adopts a preparation method combining a reflux method and an ultrasonic / microwave-assisted impregnation method, and comprises the following two steps: 1) grafting an amino silane coupling agent by adopting the reflux method to modify halloysite nanotubes; and 2) loading an active component on the halloysite nanotube obtained in the step 1) by using an ultrasonic / microwave-assisted impregnation method.The catalyst prepared in the invention shows good catalytic performance in an acetylene hydrochlorination reaction process, the acetylene conversion rate reaches 97.34%, and the vinyl chloride selectivity reaches up to 99.68%.

Exhaust gas purification device (100), comprising: a substrate (10) comprising an upstream end (I) through which an exhaust gas is introduced into the device and a downstream end (J) through which the exhaust gas is discharged from the device, wherein the substrate (10) has a length Ls between the upstream end (I) and the downstream end (J); a first catalyst layer (20) containing palladium particles, which extends over a first region (X) and is in contact with the substrate (10), wherein the first region (X) extends between the upstream end (I) and a first position (P), wherein the first position (P) is located at a first distance La from the upstream end (I) in the direction of the downstream end (J); a second catalyst layer (30) containing rhodium particles, which extends over a second region (Y) and is in contact with the substrate (10), wherein the second region (Y) extends between the downstream end (J) and a second position (Q), the second position (Q) being located at a second distance Lb from the downstream end (J) in the direction of the upstream end (I); and a third catalyst layer (40) containing rhodium particles, which extends over a third region (Z) and is in contact with at least the first catalyst layer (20), wherein the third region (Z) extends between the upstream end (I) and a third position (R), wherein the third position (R) is located at a third distance Lc from the upstream end (I) in the direction of the downstream end (J), wherein a mean particle size distribution of the rhodium particles contained in the second catalyst layer (30) and the third catalyst layer (40) is from 1.0 nm to 2.0 nm, and a standard deviation of the particle size distribution of the rhodium particles contained in the second catalyst layer (30) and the third catalyst layer (40) is 0.8 nm or less.

The invention relates to a carbon-supported noble metal ordered alloy electrocatalyst capable of realizing mass production. The electrocatalyst comprises a carbon carrier and small-size noble metal ordered alloy nanoparticles loaded on the carrier, the loading capacity of the alloy is 20 to 90 weight percent; the average particle size of the precious metal ordered alloy nanoparticles is 1-10 nm; the noble metal ordered alloy comprises an alloy consisting of a noble metal and at least one different transition metal M; wherein the noble metal is platinum, palladium, iridium, rhodium or ruthenium. The method is used for solving the problem that the size of catalyst particles becomes large in the high-temperature ordering process, high metal loading capacity is achieved, the feed ratio is increased to 60 times, successful synthesis of the catalyst can be achieved on the gram scale level, and the method can be popularized to actual production to achieve large-scale production.

The invention provides a catalyst for maleic acid water phase hydrogenation as well as a preparation method and application thereof. The catalyst comprises a carrier, an active metal component and a nitrogen-doped carbon layer, wherein the nitrogen-doped carbon layer is formed by shrinking and carbonizing melamine and formaldehyde in pores of the carrier loaded with the active metal component, and the active metal component is coated with the nitrogen-doped carbon layer; the active metal component is selected from at least one of palladium, ruthenium, gold, rhodium and iridium, and the carrier is a spherical or granular porous material. The catalyst disclosed by the invention comprises the nitrogen-doped carbon layer formed by shrinking melamine and formaldehyde in pores of the carrier loaded with the active metal components and carbonizing, so that the active metal components of specific types can be promoted to be uniformly dispersed in the catalyst structure, and the catalytic performance is improved; meanwhile, by combining the effect of the carrier, the mechanical strength of the catalyst is effectively improved, so that the catalyst can still maintain high activity after being used in an acid environment for a long time, and the maleic acid water-phase hydrogenation reaction can be efficiently catalyzed in a long-life manner.

The invention belongs to the field of analytical chemistry, and particularly discloses a method for determining trace precious metals in copper-nickel flotation tailings. According to the method, trace precious metal in the tailings is enriched through a nickel matte assaying method, and nickel matte alloy rich in precious metal is formed; the nickel matte alloy is inlaid or crushed and doped with carbon to prepare a sample meeting the measurement requirement of the glow discharge mass spectrometry, and the content of the noble metal in the sample is measured and converted by adopting the glow discharge mass spectrometry. The method effectively solves the problems of low precious metal content in tailings and large fluctuation of detection results, improves the detection accuracy and stability, and is suitable for determination of trace precious metals such as gold, silver, platinum, palladium, rhodium and iridium.