146 results about "Chromic salt" patented technology

The invention discloses a nano-alloy catalyst for anion exchange membrane electrolyzed water and a preparation method of a membrane electrode of the nano-alloy catalyst, when any one of manganese salt, cerium salt, chromium salt, cobalt salt, lanthanum salt, ruthenium salt and iridium salt is not added, NiFe binary alloy powder is obtained, the content of Ni is 90%-100%, and the content of Fe is 0%-10%; when any one of manganese salt, cerium salt, chromium salt, cobalt salt, lanthanum salt, ruthenium salt and iridium salt is added, NiFe ternary alloy powder is obtained, the content of Ni is 76%-96%, the content of Fe is 4%, and the content of the third element is 0%-20%. The nano-alloy catalyst material for anion exchange membrane water electrolysis prepared according to the invention is good in corrosion resistance and high in stability, the total water splitting efficiency is further improved, the synthesis method is simple, the used metal salt is low in cost, the metal salt can be uniformly loaded on a substrate carrier through spraying, and industrial application of total water splitting under high current density is easy to realize.

The invention belongs to the technical field of powder metallurgy, and particularly relates to a high-toughness hard alloy and a preparation method and application thereof.The preparation method comprises the steps that tungsten powder is subjected to high-energy ball milling, and then treated tungsten powder is obtained; the preparation method comprises the following steps: dissolving water-soluble lanthanum salt, cerium salt and chromium salt, and performing spray drying to obtain La-Ce-Cr composite powder; the treated tungsten powder, titanium dioxide powder, cobalt powder, La-Ce-Cr composite powder and carbon powder are mixed, and mixed powder is obtained; sintering the mixed powder to obtain alloy powder; the tungsten carbide and the alloy powder are flexibly mixed, and a mixture is obtained; and pressing and sintering the mixture to obtain the high-toughness hard alloy. The high-toughness hard alloy is a plate-shaped crystal hard alloy and is uniform in organization structure, the hardness HV10 is larger than or equal to 1620, and the fracture toughness KiC is larger than or equal to 24 MPa.m < 1 / 2 >.

The invention belongs to the technical field of catalyst preparation, and particularly relates to a catalyst special for tetrachloropropane dehydrochlorination and a preparation method and application thereof. The preparation method of the catalyst comprises the following steps: (1) placing gamma-alumina powder in a solvent, adding an amino-containing silane coupling agent, and heating for reaction to obtain modified gamma-alumina powder; and (2) preparing modified gamma-alumina powder loaded with trivalent iron salt or trivalent chromium salt, and drying to obtain the special catalyst for dehydrochlorination of tetrachloropropane. Iron ions or chromium ions complexed by an amino silane coupling agent improve the stability of the active component, the active component is attached to a gamma-alumina matrix by the catalyst, the activity of the main catalyst can be effectively regulated and controlled, the phenomena of chlorine absorption, coking and the like are reduced, the dehydrochlorination reaction is carried out when tetrachloropropane is in contact with the solid matrix, and the dehydrochlorination reaction is carried out when the tetrachloropropane is in contact with the solid matrix. On the basis of high conversion rate and selectivity, side reaction is avoided.

The invention relates to a metal passivator, and particularly discloses an environment-friendly passivation solution for a metal component and a preparation method and a passivation process of the environment-friendly passivation solution. The passivation solution comprises 1%-5% of trivalent chromium salt, 1%-5% of silicon-containing compound modified alkyd resin, 2%-15% of a film forming accelerant, 5%-15% of a complexing agent, 1.5%-2% of a hole sealing agent and the balance deionized water. The low-content trivalent chromium salt is adopted to replace traditional hexavalent chromium salt, the toxicity of trivalent chromium is far lower than that of hexavalent chromium, heavy metal pollution hazards are effectively reduced, and by adding assistants such as the silicon-containing compound modified alkyd resin, the hole sealing agent, the film forming accelerant and the complexing agent, through the synergistic effect of all the components, the corrosion resistance of the coating is improved, and the service life of the coating is prolonged. A compact, uniform and stable passivation film is formed on the surface of the sherardizing steel part, the probability of rusting and corrosion of the sherardizing steel part is remarkably reduced, the service life of the sherardizing steel part in severe environments such as high humidity and high salinity is prolonged, and high practical value is achieved.

The invention belongs to the technical field of lithium ion batteries, and particularly relates to a high-entropy fluoride electrode material and a preparation method and application thereof. The preparation method of the high-entropy fluoride electrode material comprises the following steps: dispersing a surfactant in a solvent, adding a soluble iron salt, a soluble nickel salt, a soluble manganese salt, a soluble copper salt and a soluble chromium salt, uniformly mixing, and adding a fluorine source to obtain a precursor solution; the precursor solution is placed at the temperature of 120 DEG C to 140 DEG C for a reaction, uniform FeF3, NiF2, MnF2, CuF2 and CrF3 are formed, and a high-entropy fluoride precursor is obtained; and annealing the high-entropy fluoride precursor in a protective atmosphere to obtain the high-entropy fluoride electrode material. The high-entropy fluoride electrode material prepared by the invention shows excellent reversible capacity and excellent cycling stability.

The invention relates to a fluorination catalyst and a method for preparing 2-chloro-3, 3, 3-trifluoropropene. The fluorination catalyst is prepared by the following steps: 1) loading a water-soluble trivalent chromium salt on aluminum oxide according to a molar ratio of Cr to Al of 1: (5-20) by an impregnation method to obtain aluminum oxide loaded with the water-soluble trivalent chromium salt; 2) drying the aluminum oxide loaded with the water-soluble trivalent chromium salt, and roasting at 200-300 DEG C for 2-8 hours to obtain a catalyst precursor; and 3) fluorinating the catalyst precursor with hydrogen fluoride to prepare the fluorination catalyst. The catalyst disclosed by the invention is high in stability, and can be used for preparing 2-chloro-3, 3, 3-trifluoropropene with a simple process and high conversion rate and selectivity.

The invention discloses a preparation method of a thermal oxidation anode. The preparation method comprises the following steps: pretreating a substrate; then nickel salt, ferric salt, chromium salt, cerium salt, sodium citrate, citric acid and isopropanol are selected and dissolved in water, and a mixed coating solution is obtained; then carrying out first-stage high-temperature oxidation treatment on the nickel substrate; secondly, the oxidized nickel net is coated with prepared coating liquid for second-stage thermal oxidation treatment, a thermal oxidation anode is formed, multiple second-stage thermal oxidation treatment is conducted many times to obtain multiple stacked catalyst layers, and the catalyst layers and the base body are firmly combined and are not prone to falling off; after the outer catalyst layer falls off, the inner catalyst layer can continue to carry out oxygen evolution reaction without influencing the strength and stability of the reaction, the service life of the electrode is greatly prolonged, the metal salt is added to form an oxide at high temperature, so that the electrode has good corrosion resistance, the transition metal is used to save the cost, the overpotential is effectively reduced, and the service life of the electrode is prolonged. And the service life is long.

The invention belongs to the technical field of micro-nano composite materials, and particularly relates to a chromium-based bimetallic sulfide-porous carbon composite material and a preparation method and application thereof. The preparation method of the chromium-based bimetallic sulfide-porous carbon composite material provided by the invention comprises the following steps: mixing chromium salt and zinc salt, or chromium salt and manganese salt with a sulfur source, sodium gluconate and a pore-forming agent, and preparing the composite material through heat treatment and vulcanization technologies. The chromium-zinc or chromium-manganese bimetallic sulfide-porous carbon composite material prepared by the preparation method has good structural stability and conductivity, and the cycling stability of a battery can be remarkably improved when the chromium-zinc or chromium-manganese bimetallic sulfide-porous carbon composite material is used as a battery material. The prepared chromium-based bimetallic sulfide-porous carbon composite material has important application value in the field of lithium ion battery electrode materials.

The present invention relates to the technical field of chemistry, particularly to a 2, 3, 3, 3-tetrafluoropropene preparation method, which comprises: mixing a water-soluble metal salt containing a first metal auxiliary agent and chromium chloride hexahydrate to prepare a first solution, mixing the first solution with first ammonia water, and carrying out first calcination treatment on the obtained first precipitate to obtain a first chromium salt; mixing first chromium salt with graphite and silicon dioxide to obtain a first catalyst precursor, and performing fluorination activation treatment on the first catalyst precursor to obtain a first catalyst; the method comprises the following steps: under the action of a first catalyst, reacting 2-chloro-3, 3, 3-trifluoropropene with hydrogen fluoride to obtain 2, 3, 3, 3-tetrafluoropropene. According to the method, the process route is shortened, the use of highly toxic substances is avoided, the cost is reduced, the pollution to the environment is reduced, and meanwhile, the conversion rate of HCFO-1233xf and the selectivity of HFO-1234yf are improved.

The invention discloses a preparation method of a high-entropy Prussian blue analogue material CuCoNiCrMn-PBA (Prussian blue analogue) and a preparation method of the high-entropy Prussian blue analogue material. The preparation method comprises the following steps: dissolving a copper salt, a cobalt salt, a nickel salt, a chromium salt, a manganese salt and sodium citrate in deionized water, dropwise adding the solution and a sodium ferrocyanide salt solution into the deionized water at the same time, carrying out a co-precipitation reaction, adding ascorbic acid after co-precipitation is finished, stirring, and carrying out an Ostwald ripening process to obtain the high-entropy Prussian blue analogue material. When the material is used as a sodium ion battery positive electrode active material, the material has relatively high specific discharge capacity, relatively good cycling stability and excellent rate capability. The high-entropy Mn-based Prussian blue analogue material with multiple elements coordinated with N atoms is synthesized, the Jahn-Teller effect of the Mn element is inhibited while the capacity is provided by multiple transition metal elements, the framework structure is wide and stable, and the method has the advantages of being easy to operate, high in safety, high in yield and the like.

The invention discloses a halogen anion doped chromic oxide electrocatalyst and a preparation method and application thereof, and belongs to the technical field of new energy materials and electrochemical catalyst.The preparation method of the electrocatalyst comprises the steps that soluble chromium salt and polyvinylpyrrolidone are dissolved in a mannitol solution and then mixed with a soluble halogen salt solution, stirring is conducted, and the electrocatalyst is obtained; preparing to obtain a mixed solution; in a closed environment, heating the mixed solution at 160-180 DEG C for 6-24 hours to perform hydrothermal reaction, obtaining a reaction product after the reaction is finished, and then calcining in an air atmosphere to prepare the powdery halogen anion doped chromic oxide electrocatalyst, according to the method, the local structure, the spinning state, the energy band and the like of chromic oxide are regulated and controlled through the doped halogen anion ligand, the OER catalytic activity of the chromic oxide is optimized, the process is simple, and the method has good application prospects in the water electrolysis technology.

The application provides a one-dimensional high-entropy alloy, a preparation method and application of the one-dimensional high-entropy alloy in CO2 ring addition reaction, and relates to the technical field of high-entropy alloys.The molar ratio of iron salt, cobalt salt, nickel salt, manganese salt, chromium salt and cerium salt in the one-dimensional high-entropy alloy is 1:1:1:1:1:1;the high-entropy alloy has a fiber structure, the fiber has a hierarchical pore structure which is interconnected, including macropores or mesopores formed by decomposition of the self-sacrificing template 1, and mesopores or micropores formed by decomposition of the self-sacrificing template 2.Through improvement of the process conditions, the one-dimensional high-entropy alloy material with a unique structure can be prepared under relatively mild conditions, so that the whole reaction process is safer and more economical, and meets the goal of green chemistry and sustainable development.Meanwhile, the one-dimensional high-entropy alloy material prepared provides a large specific surface area, fully exposes active sites, and can realize efficient and stable conversion of the carbon dioxide ring addition reaction.

The invention discloses a preparation method and application of an anode oxygen evolution catalyst. The preparation method comprises the following steps: respectively putting untreated foamed nickel with the area of 2cm * 4cm into a hydrochloric acid solution, deionized water and ethanol, and carrying out ultrasonic treatment for a certain time; and obliquely inserting the treated foamed nickel into a reaction kettle filled with a nickel salt, an iron salt, a chromium salt and a precipitator, putting the reaction kettle into a blast oven for hydrothermal reaction, naturally cooling to room temperature after the reaction is completed, and washing with deionized water to obtain the foamed nickel supported chromium-doped ferronickel layered hydroxide anode oxygen evolution catalyst. The anode catalyst prepared by the method provided by the invention has better long-term durability under large current density, and in the OER process, the dissolution of chromium can promote the reconstruction of the nickel-iron catalyst and generate more active sites and pore channels, so that the electrochemical active area of the nickel-iron-based catalyst is increased, and the permeation of electrolyte and the diffusion of ions are promoted.

The invention discloses a chromium-free and formaldehyde-free synergistic tanning method for high-flexibility ecological Tan sheep skin, which comprises the following steps: firstly, pre-tanning the Tan sheep skin by using a 6-10g / L biomass-based aldehyde tanning agent, and then carrying out zirconium tanning and synergistic tanning to obtain chromium-free and formaldehyde-free tanned Tan sheep skin. The bio-based aldehyde tanning agent is prepared through selective oxidation of glycerin, the structure of the bio-based aldehyde tanning agent contains aldehyde groups and hydroxyl groups, polyglyceraldehyde with a long-chain structure can be formed through polymerization by adjusting the pH value, and then the polyglyceraldehyde is covalently cross-linked with collagen amino groups; the introduction of the zirconium tanning agent not only can be complexed with collagen carboxyl, but also can be coordinated with hydroxyl on the structure of the biomass-based aldehyde tanning agent to form a multi-point cross-linked network, so that the flexibility and damp-heat resistance stability of the Tibet lamb skin are remarkably improved, and meanwhile, the health and environmental risks caused by chromium salt and formaldehyde are thoroughly eliminated.

The invention provides a composite metal oxide for preparing aromatic hydrocarbon from synthesis gas and application of the composite metal oxide. Raw materials of the composite metal oxide comprise chromium salt, indium salt, ferric salt, zinc salt and aluminum salt. The indium oxide of the composite metal oxide has relatively high CO hydrogenation and reverse water gas change reaction activity, not only can improve the activity of converting CO on the oxide into an oxygen-containing intermediate, but also can optimize the product distribution and effectively reduce the CO2 selectivity in the product, and also has relatively high aromatic hydrocarbon selectivity; the catalyst can catalyze synthesis gas to be converted into aromatic hydrocarbon, the selectivity of a by-product CO2 is low, the reaction efficiency is high, and oxides are not prone to inactivation. Besides, the composite metal oxide prepared by decomposing the metal precursor at a high temperature by using the high-boiling-point organic solvent has a relatively stable structure, so that the migration of metal to the molecular sieve is effectively inhibited, and the reaction stability of preparing the aromatic hydrocarbon from the synthesis gas is greatly improved.

The invention discloses a preparation method of ethylhexyl palmitate, and relates to the technical field of ethylhexyl palmitate. According to the method, firstly, isooctanol is gasified and then introduced into a methyl palmitate solution, ethylhexyl palmitate is prepared through transesterification, gaseous feeding can improve the instantaneous concentration of alcohol in a liquid phase, the reaction is promoted to be carried out in the positive direction, the reaction rate is increased, meanwhile, methanol generated through the transesterification method can be gasified and taken out of a system, and the yield of ethylhexyl palmitate is increased. Forward proceeding of the reaction is further promoted, so that the reaction is more thorough; secondly, chromium salt is used as a metal source precursor and a 2-sulfo-4, 4 '-biphenyldicarboxylic acid ligand to synthesize a catalyst, a biphenyl group in the ligand provides rigid and hydrophobic large pore channels and provides a local high-concentration reaction environment, gaseous isooctanol can be easily diffused into the pore channels of the catalyst and is in contact with enriched methyl palmitate, and the reaction efficiency is improved; and sulfonic acid groups uniformly distributed in the ligand serve as solid superacid, strong acid sites are provided, and the production efficiency is improved.

The invention discloses a method for preparing benzyl borate compounds through chromium catalysis, and belongs to the technical field of organic synthesis. According to the method, aryl carboxylic ester is taken as a raw material, pinacolborane is taken as a boron source and a hydrogen source, metal chromium salt is taken as a catalyst, a specific ligand and elemental magnesium are added, and reaction is performed in a tetrahydrofuran solvent, so that the deoxidation boronization reaction of the aryl carboxylic ester is realized. Benzyl monoborate or benzyl subunit diborate can be selectively prepared through ligand regulation and control. The method has the advantages of mild reaction conditions, cheap catalyst, wide raw material source, simple operation and good chemical selectivity.

The invention relates to a trivalent chromium passivation solution and a preparation method thereof, and belongs to the technical field of passivation solutions. In the trivalent chromium passivation solution, the concentration of trivalent chromium salt is 80 g / L-90 g / L, the concentration of an oxidation accelerant is 65 g / L-75 g / L, the concentration of a coordination agent is 10 g / L-15 g / L, the concentration of a pH buffering agent is 8 g / L-12 g / L, the concentration of an activating agent is 10 g / L-15 g / L, the concentration of a grain refiner is 4 g / L-6 g / L, the concentration of cobalt salt is 60 g / L-75 g / L, the concentration of nickel salt is 220 g / L-240 g / L, and the concentration of an oxidizing agent is 20 g / L-30 g / L; the concentration of the complexing agent is 50 g / L-60 g / L, and the concentration of the nano silica gel is 8 g / L-12 g / L. The problem of hexavalent chromium pollution is eliminated, the problems that a trivalent chromium passivation film is poor in corrosion resistance and uneven in blackness are solved, and the process stability can be improved.

A threaded end of a tubular component is for drilling and / or operating a hydrocarbon well, transporting oil and gas, transporting or storing hydrogen, carbon capture or geothermal energy, comprising at least one thread extending over its outer or inner peripheral surface, wherein the thread is coated with a layer comprising a zinc-chromium (Zn—Cr) alloy in which zinc (Zn) is the predominant element by weight, relative to the total weight of the alloy. A process for preparing a threaded end, as defined above, includes at least one electrodeposition, on the surface of the thread of the end, of an aqueous composition comprising one or more zinc salts, one or more chromium salts, one or more electrolytes and one or more surfactants.

The application relates to the technical field of long-afterglow materials, and particularly provides a preparation method of a near-infrared long-afterglow luminescent nano probe and application thereof. The preparation method of the near-infrared long-afterglow luminescent nano probe comprises the following steps: dissolving water-soluble zinc salt, water-soluble tin salt, water-soluble gallium salt, water-soluble chromium salt and water-soluble yttrium salt in water to prepare a metal mixed solution with a salt concentration of 0.1-2 mol / L; adding mesoporous silica powder into the metal mixed solution, uniformly dispersing, stirring for 30 min-48 hours, adding an alkaline precipitant drop by drop until the pH is 8-10, collecting the precipitate, drying, high-temperature calcining, and obtaining doped particles; and coating manganese dioxide on the surface of the doped particles, and the near-infrared long-afterglow luminescent nano probe has the characteristics of slow afterglow decay.

The invention is suitable for the technical field of electrochemical catalysts, and provides a preparation method and application of an MOF-derived NiCr2O4 (at) C catalyst, and the method comprises the following steps: mixing nickel salt, chromium salt and terephthalic acid in a solvent to form a mixed solution; wherein the molar ratio of the nickel salt to the chromium salt is (1-2): 1; carrying out solvothermal reaction on the obtained mixed solution at 120-160 DEG C for 6-18 hours, and washing and drying a reaction product to obtain a NiCr-MOF precursor; and carrying out heat treatment on the NiCr-MOF precursor in an inert atmosphere at 450-650 DEG C for 1-3 hours to obtain the NiCr2O4-C catalyst. The obtained catalyst has an MOF-derived porous carbon composite structure, shows about 100% H2O2 selectivity, high catalytic activity and excellent stability in alkaline electrolyte, is simple in preparation method and good in repeatability, and provides a high-performance and low-cost solution for green electrosynthesis of hydrogen peroxide.

The embodiment of the invention provides an electrochemical sensor for detecting penicillin as well as a preparation method and application of the electrochemical sensor. The electrochemical sensor comprises a base electrode, a first solid film and a second solid film, wherein the first solid film and the second solid film are sequentially stacked on the base electrode; the first solid film is a multi-walled carbon nanotube, and the second solid film is an MIL-101-NH2 (Cr) composite material; the MIL-101-NH2 (Cr) composite material is a metal organic framework material formed by copolymerization of trivalent chromium salt and 2-aminoterephthalic acid. According to the electrochemical sensor for detecting penicillin as well as the preparation method and the application of the electrochemical sensor, penicillin molecules can be detected, and the detection limit can reach 2.071 mu mol / L; the method can be widely applied to detection of penicillin in foods such as dairy products.

The invention relates to a hollow high-entropy transition metal hydroxide crystal and a preparation method thereof. The preparation method comprises the following steps: providing a cuprous oxide crystal; the preparation method comprises the following steps: respectively adding a nickel salt precursor, a cobalt salt precursor, a chromium salt precursor, a manganese salt and / or iron salt precursor and cuprous oxide crystals into an ethanol / water mixed solvent to prepare uniformly dispersed suspension liquid; adding polyvinylpyrrolidone into the suspension, and fully mixing to obtain a mixed solution; and dropwise adding a reactant containing thiosulfate radicals into the mixed solution, reacting, and separating to obtain the hollow high-entropy transition metal hydroxide crystal. The method is simple in process, mild in condition, short in reaction time, low in requirement for precision of equipment and instruments, high in controllability of product morphology, good in repeatability and especially suitable for large-scale industrial production.

The application provides a metal-carbon skeleton nano-microparticle and a preparation method thereof, and belongs to the field of nanometer material preparation, wherein the metal-carbon skeleton nano-microparticle is prepared from raw materials through a solvothermal reaction; the raw materials comprise, in percentage by mass, 3-15% of polymerizable monomers, 0.05-1.5% of initiators, 0.01-1.5% of metal salts and the balance of solvents; the active functional groups of the polymerizable monomers comprise nitrogen and / or oxygen; and the metal salts comprise at least one of aluminum salts, zirconium salts, chromium salts and zinc salts. The application uses metal ions and organic precursors containing active groups as raw materials, realizes controllable adjustment of the particle size of the nano-microparticles in the range of 1-5000 nanometers through metal crosslinking, induced nucleation and in-situ carbonization processes. The preparation process of the application is simple and controllable, the obtained nano-microparticles are uniform in size, stable in structure, high in temperature resistance and salt resistance, and can be widely applied in the fields of catalysis, sensing or oil displacement.

The invention relates to the technical field of pretreatment of aluminum foil before lithium ion battery soft package aluminum plastic film covering, in particular to a trivalent chromium passivation solution for aluminum foil coating with high electrolyte resistance and a preparation method of the trivalent chromium passivation solution, and the formula of the trivalent chromium passivation solution comprises trivalent chromium salt, hexafluorozirconic acid, a film-forming agent, a film-forming accelerant and deionized water; the weight ratio of the trivalent chromium salt to the hexafluorozirconic acid to the film-forming agent to the film-forming accelerant in each liter of the trivalent chromium passivation solution is (6-10) g: (0.02-0.05) g: (10-15) g: (15-20) g, and the balance is deionized water. The trivalent chromium passivation solution is mainly used for pretreatment of aluminum foil before lithium ion battery soft package aluminum-plastic film lamination, an organic and inorganic composite film is generated on the surface of the aluminum foil through reaction, the bonding strength of aluminum-plastic lamination can be greatly improved, and the trivalent chromium passivation solution has ultrahigh electrolyte resistance.

The invention provides an inorganic antioxidant carbon-coated nickel-chromium catalyst as well as a preparation method and application thereof. The preparation method comprises the following steps: uniformly mixing nickel salt, chromium salt and a carbon source to obtain a precursor; the molar ratio of the nickel element to the chromium element is (1: 1)-(5: 1); the carbon source is selected from one or more of citric acid, tartaric acid, nitrilotriacetic acid, malic acid, ethylenediamine tetraacetic acid and ethylenediamine tetraacetic acid sodium salt; and pyrolyzing the precursor in an inert atmosphere to obtain the carbon-coated nickel-chromium catalyst. According to the method, a chromium element is introduced and carbonized in an inert atmosphere to form a Ni-Cr metal / oxide-carbon coated integrated structure, an inorganic anti-oxidation system taking a Cr oxygen-containing phase and a carbon shell as a core is constructed, and the anti-oxidation capability and the structural stability of metal Ni under air and oxygen-containing conditions are improved on the premise of not depending on an organic ligand or an organic coating layer; the catalyst is especially suitable for hydrogenation reaction of styrene and other aromatic olefins.

The application provides a composite metal oxide for synthesizing aromatic hydrocarbons from synthesis gas and application thereof; raw materials of the composite metal oxide include chromium salt, indium salt, iron salt, zinc salt and aluminum salt. The indium oxide of the composite metal oxide has high CO hydrogenation and reverse water gas shift reaction activity, can not only improve the activity of converting CO into oxygen-containing intermediates on the oxide, but also optimize product distribution, effectively reduce the CO2 selectivity in the product, and has high aromatic hydrocarbon selectivity; can catalyze synthesis gas to be converted into aromatic hydrocarbons, has low CO2 selectivity in by-products, high reaction efficiency, and the oxide is not easy to be deactivated. In addition, the composite metal oxide prepared by high-boiling-point organic solvent high-temperature decomposition of metal precursors is fast and simple, has a relatively stable structure, effectively inhibits the migration of metal to the molecular sieve, and greatly improves the reaction stability of synthesis gas for aromatic hydrocarbons.

The application relates to the technical field of electroplating, and discloses a chromium electroplating process for improving the hardness of a connector terminal, which comprises the following steps: performing surface pretreatment on the connector terminal, removing surface impurities through ultrasonic cleaning and micro-etching treatment; performing heating treatment on the connector terminal; performing electroplating treatment on the connector terminal by using an electroplating solution comprising trivalent chromium salt, boron nitride nanoparticles, ferroferric oxide nanoparticles, nickel ions, sodium dichromate and chromium alloy additives, so as to form a chromium plating layer; performing passivation treatment on the plating layer; performing low-temperature treatment on the plating layer; and spraying a protective layer on the chromium plating layer. Through the trivalent chromium salt and the sodium dichromate, the trivalent chromium salt is used to reduce hexavalent chromium ions into trivalent chromium, the toxicity of the hexavalent chromium is reduced, the sodium dichromate is used to provide a stable chromium source, the deposition of chromium elements in the electroplating process is ensured, the pollution of hexavalent chromium to the environment and the harm of hexavalent chromium to the health of operators are solved, and the environmental protection and safety of the electroplating process are improved.

The invention discloses a method for preparing pseudo-boehmite by using sodium dichromate mother liquor to neutralize sodium aluminate and sodium chromate liquid, which comprises the following steps: simultaneously introducing the sodium dichromate mother liquor and the sodium aluminate and sodium chromate liquid into a stirring reactor in which soft water is added in advance, stirring to react, and increasing the concentration of reaction materials along with continuous introduction and finally achieving balance, after being balanced, the materials flow out from the overflow port and are transferred to the next process, and at the moment, the materials are still continuously fed, so that continuous feeding and continuous discharging are realized; and feeding the reacted material into an aging tank, heating, aging, washing with water, and drying to obtain the pseudo-boehmite product. According to the invention, resource utilization of the aluminum element in a chromium salt chemical production system is realized; meanwhile, the sodium dichromate mother liquor is used for providing an acid value for a neutralization reaction, and acid recycling is achieved; the pseudo-boehmite produced by the method disclosed by the invention has a relatively high specific surface area, a relatively large pore volume and a relatively concentrated average pore size.

The application provides a chromium-based composite catalyst preparation method and application thereof, and belongs to fluorine chemical technology, wherein the chromium-based composite catalyst preparation method comprises the following steps: S1: dissolving chromium salt, soluble salt corresponding to an auxiliary component metal and fluorine-containing polymer in deionized water, stirring and dissolving, then adding a precipitant and continuing to stir for a set time to obtain a precipitate mixture; S2: loading the precipitate mixture obtained in the step S1 into a centrifugal container, centrifugally washing, drying, and then high-temperature calcining to obtain a composite metal oxide. The chromium oxide catalyst is prepared by using the precipitation method, fluorine-containing polymer is used as a fluorine source, hydrogen fluoride is decomposed and released in the calcining process, and thus the in-situ fluorination of the metal is prepared in one step, and the prepared catalyst has the advantages of simple preparation method, large specific surface area and high stability.