342 results about "Tungsten acid" patented technology

To provide a laminated structure for shielding against solar radiation having high solar radiation blocking characteristics with low manufacturing costs. Fine particles 11 functioning to block solar radiation are obtained by firing tungstic acid under a reductive atmosphere, a liquid dispersion to form a solar radiation blocking material is prepared by crashing and dispersing treatment of the fine particles, a polymer base dispersing agent, and solvent, and thus prepared liquid dispersion to form a solar radiation blocking material is added to vinyl resin, which is molded into a sheet shape to obtain an intermediate film 12. Thus obtained intermediate film 12 is sandwiched between two sheets to be laminated selected from sheet-glass or plastic to obtain an intermediate layer 2, which is heated and bonded each other to prepare a laminated structure for shielding against solar radiation.

The invention discloses a method for extracting tungsten, titanium and vanadium from a waste SCR (selective catalytic reduction) catalyst, which comprises the following steps: crushing the waste SCR catalyst, adding a strongly alkaline solution, and reacting; filtering, separating, then adding strong acid into the sodium tungstate and sodium vanadate mixed solution, and reacting to obtain tungstic acid and a sodium salt and vanadic acid mixed solution; regulating the pH value of the sodium salt and vanadic acid mixed solution until precipitate is separated out, thus obtaining ammonium vanadate; then adding sulfuric acid into the tungsten-and-vanadium-removed SCR catalyst, and reacting to obtain a titanyl sulfate solution and solids such as aluminum slag and the like; then adding water into the titanyl sulfate solution, and hydrolyzing to obtain titanic acid and a waste acid solution; and finally, respectively calcining the obtained ammonium vanadate, tungstic acid and titanic acid to obtain vanadium pentoxide, tungsten trioxide and titanium dioxide. According to the invention, tungsten, titanium and vanadium can be extracted from the SCR catalyst through the reaction with strong alkali and strong acid at a low temperature, the equipment requirement is low, the energy consumption is low, some products having added values can be coproduced, and no secondary pollution is generated, thereby facilitating popularization and application.

The invention provides a method for preparing ethylene glycol and 1,2-propylene glycol by using a high-concentration saccharide solution. Reaction raw materials comprise cane sugar, glucose, fructose, fructosan, xylose, soluble lower polyxylose and soluble starch. According to the method, high-concentration saccharide is used as a reaction raw material, and a high-pressure pump feeding mode is used in a reaction process which is performed in a high-pressure reaction kettle; iron, cobalt, nickel, ruthenium, rhodium, palladium, iridium and platinum which serve as transition metal in eighth, ninth and tenth groups are used as hydrogenation active ingredients; the hydrogenation active ingredients form a composite catalyst together with metal tungsten, tungsten carbide, tungsten nitride, tungsten phosphide, tungsten oxide, tungsten sulfide, tungsten chloride, tungsten hydroxide, tungsten bronze, tungstic acid, tungstate, metatungstic acid, metatungstate, paratungstic acid, paratungstate, peroxotungstic acid, peroxotungstate and tungsten-containing heteropolyacid which serve as catalytic active ingredients; and the high-concentration saccharide solution can be efficiently prepared into the ethylene glycol and the propylene glycol at high selectivity and high yield in a one-step catalytic conversion process under the hydrothermal condition that the temperature is 120 to 300 DEG C and the hydrogen pressure is 1 to 13MPa. By the method, the problem of coking of the high-concentration saccharide in the catalytic conversion process can be effectively solved, and high-concentration ethylene glycol and propylene glycol can be prepared by the high-concentration saccharide.

This invention provides novel cadmium tungstate scintillator materials that show improved radiation hardness. In particular, it was discovered that doping of cadmium tungstate (CdWO4) with trivalent metal ions or monovalent metal ions is particularly effective in improving radiation hardness of the scintillator material.

This invention provides methods for producing ethylene glycol from polyhydroxy compounds such as cellulose, starch, hemicellulose, glucose, sucrose, fructose, fructan, xylose and soluble xylooligosaccharides. The methods uses polyhydroxy compounds as the reactant, a composite catalyst having active components comprising one or more transition metals of Groups 8, 9, or 10, including iron, cobalt, nickel, ruthenium, rhodium, palladium, iridium, and platinum, as well as tungsten oxide, tungsten sulfide, tungsten hydroxide, tungsten chloride, tungsten bronze oxide, tungsten acid, tungstate, metatungstate acid, metatungstate, paratungstate acid, paratungstate, peroxotungstic acid, pertungstate, heteropoly acid containing tungsten. Reacting at a temperature of 120-300° C. and a hydrogen pressure of 1-13 MPa under hydrothermal conditions to accomplish one-step catalytic conversion. It realizes efficient, highly selective, high yield preparation of ethylene glycol and propylene glycol from polyhydroxy compounds. The advantage of processes disclosed in this invention include renewable raw material and high atom economy. At the same time, compared with other technologies that converts biomass raw materials into polyols, methods disclosed herein enjoy advantages including simple reaction process, high yield of targeted products, as well as easy preparation and low cost for the catalysts.

The invention relates to a method for separating tungsten and molybdenum. The method comprises the following steps: (1) adding acid into a tungsten-molybdenum mixed solution and adjusting pH value to obtain mixed sediment of tungsten acid and molybdenum acid; (2) adding hydrogen peroxide and acid into the mixed sediment to form peroxide tungsten acid and peroxide molybdenum acid; (3) heating an obtained mixed solution, adding tungsten powder, reacting and filtering to obtain tungsten acid sediment and a molybdenum-containing acid solution; (4) calcining the prepared tungsten acid to prepare tungsten trioxide or dissolving by using ammonium hydroxide to obtain an ammonium tungstate solution and then evaporating and crystallizing to prepare APT; (5) extracting the molybdenum in the obtained molybdenum-containing acid solution by using an extraction agent / ion exchange resin; and (6) reversely extracting molybdenum-containing organic phase / resin by using ammonium hydroxide to obtain the ammonium molybdate solution, and carrying out acid precipitation to obtain ammonium tetramolybdate. The production process of tungsten-molybdenum products is taken into account in the method, so that the separated tungsten acid or molybdenum can be directly used for preparing the products thereof; the separation effect is excellent; the operation process is simple and is liable to control; the industrial popularization and application are liable to implement.

The invention belongs to the field of tungsten resource recycling, and particularly relates to a method for regenerating APT (ammonium paratungstate) by the use of waste low-grade tungsten slag in an APT production process. The invention discloses a method for regenerating APT by use of APT waste low-grade tungsten slag, which is realized by improving the technological parameters of the traditional soda sintering method and comprises the following steps of: (a) grinding and dosing; (b) slag calcining; (c) wet grinding and filtering; (d) two-secondary ion exchange and impurity removal; and (e) evaporating and crystallizing to generate APT. The method provided by the invention can reduce resource waste, improve the utilization rate of resources, and can increase the economic benefits of an enterprise by recycling the APT waste low-grade tungsten slag; the method is suitable for treating the waste low-grade tungsten slag of which the WO3 grade is 2-10%, overcomes the shortcomings of the technology matching the waste and the tungsten concentrate raw material, and can effectively improve the recovery rate of tungsten and reduce environmental pollution; and through the invention, the service life of the tungsten resource of the country can be prolonged, the current situation of shortage in tungsten resource is relieved, the emission of waste can be effectively reduced, and environmental pollution is reduced.

The invention relates to a method for recovering nonferrous metals from a waste denitration catalyst, and specifically relates to a method for recovering vanadium and tungsten from a tungsten containing vanadium-titanium based waste denitration catalyst. The method mainly comprises the following steps: crushing and grinding the catalyst, adding hydrogen peroxide to enable part of vanadium oxide to form pervanadic acid, and filtering to obtain a filter cake and a filtrate containing pervanadic acid; after heating the filtrate, filtering again to obtain V2O5, and mixing and circulating to use a novel filtrate and hydrogen peroxide; adding alkali liquor to the filter cake, stirring and heating, leaching the residual vanadium in form of metavanadate and leaching tungsten in form of metatungstate; filtering to obtain mixed liquor of metavanadate and metatungstate; adding ammonium salt into the mixed liquor to separate out ammonium metavanadate precipitate, further filtering to obtain an ammonium metavanadate filter cake and a third filtrate, and adding a concentrated acid into the third filtrate to separate out tungstic acid precipitate. The method and process provided by the invention are simple, and when metavanadate and tungstic acid are leached, calcination is avoided, so that the energy consumption is low, the solid-liquid reaction is good in contact, and the recovery rates of vanadium and tungsten are high.

The invention discloses a tungsten trioxide nano-film with photocatalytic performance, and a preparation method thereof. The tungsten trioxide nano-film is characterized in that a WO3 nano layer with a WO3 nano structure is grown on a WO3 crystal seed layer, and the WO3 nano structure is shaped like a two-dimensional flying saucer including a middle main sheet and a nano-column. The preparation method of the tungsten trioxide nano-film comprises the steps of preparing a tungsten acid crystal seed layer precursor solution, preparing FTO (Fluorine-doped Tin Oxide) conductive glass with the crystal seed layer, preparing thermal tungsten acid solvent precursor solution, and finally performing hydrothermal synthesis to obtain the tungsten trioxide nano-film. According to the tungsten trioxide nano-film with photocatalytic performance, and the preparation method thereof, the specific surface area of the WO3 nano layer can be effectively enlarged; the efficiency of photocatalytic water splitting can be improved, the performance of photocatalytic water splitting in a photoelectric chemical pool is excellent, and excellent chemical stability can be achieved, the preparation method is simple, and the low-cost and large-scale application can be realized.

The invention discloses a super-wide-temperature-range nickel-hydrogen battery. The battery comprises an iron shell as well as a nickel electrode, a hydrogen electrode, a diaphragm and an electrolyte solution mounted in the iron shell, wherein the nickel electrode takes foam nickel as a substrate material; the space in foam nickel is filled with a positive electrode active substance Ni(OH)2, a conductive agent, an additive and a binder; the hydrogen electrode takes a porous nickel-plated steel belt, a copper net or foam nickel as a substrate material; the porous nickel-plated steel belt, the copper net or foam nickel is coated with a negative electrode active substance, namely, hydrogen storage alloy powder, the conductive agent, the additive or the binder; and the electrolyte solution is a mixture of a potassium-rich alkaline aqueous solution and sodium tungstate or tungstic acid crystals. The invention furthermore discloses a manufacturing method for the super-wide-temperature-range nickel-hydrogen battery. According to the super-wide-temperature-range nickel-hydrogen battery disclosed by the invention, the ratio of 0.2C discharge capacity to normal-temperature capacity maximally can reach 70-80% in an environment with the temperature of -45 DEG C; and the ratio of 0.2C discharge capacity to normal-temperature capacity of the nickel hydrogen battery maximally can reach 85-95% in an environment with the temperature of 70 DEG C. Moreover, the manufacturing method is simple and suitable for large-scale production.

The invention is a silicotungstic and phosphotungstic heteropoly acid load catalyst used for esterification reaction, which comprises the following components: Keggin structure silicotungstic acid H3SiW12O40.xH2O and phosphotungstic H3PW12O40.xH20, the content occupies 10 to 50 quality per centage of the amount of the catalyst; the carrier is H Beta zeolite. The invention adopts soaking method to prepare the solid silicotungstic and phosphotungstic heteropoly acid catalyst load on the H Beta zeolite, which can be used for catalyzing the esterification reaction of etic acid, isobutanol, isobutanol and ethanol, but also can be used for catalyzing esterification reaction of lactic acid and isobutanol to synthesis n-butyl acetate, isobutyl acetate, ethyl acetate and N-Butyl Lactate. The invention has the advantages of good stability, high activity and good selectivity, but also can used as inhomogeneous catalyst which is easy to be separated with reaction product and can use the prepared and formed catalyst powder in the continuous operating fixed bed reactor. The invention is used in the techinics of esterification reaction catalyzing rectifying.

The invention discloses an electrochromic film adopting an amorphous / crystalline tungsten trioxide core-shell structure and a preparation method of the film. The method comprises steps as follows: white tungstic acid is dissolved in a hydrogen peroxide solution, the mixture is applied to a conductive surface of a conductive substrate, and a conductive substrate covered with a crystal seed layer is obtained; a tungsten source is dissolved in water, the pH value is adjusted, ammonium sulfate is added, a precursor solution is formed, a reaction is conducted in the precursor solution at the temperature of 150-250 DEG C for 4-10 h, and a tungsten trioxide nanowire array film is obtained. The tungsten source is dissolved in the water, the hydrogen peroxide is dropwise added, the pH value is adjusted, an electrodeposition solution is formed, and the film can be obtained through electrodeposition of amorphous tungsten oxide with a constant voltage method. The film prepared with the preparation method has the nanowire core-shell coating morphology, is good in electric connectivity and has the advantages of large spectrum adjusting range, high coloration efficiency and long cycle life, meanwhile, the preparation technology is convenient to control, the production cost is lower, massive production can be realized, and industrialization is easy to realize.

The invention provides CsxWOyFz powder and a preparation method thereof. The preparation method of the CsxWOyFz powder comprises the following steps: mixing a tungstic acid solution with a fluorine source solution, and adding organic acid to form a WO3-F composite sol; adding a Cs2CO3 solution to the WO3-F composite sol to form a Cs-WO3-F composite sol; putting the Cs-WO3-F composite sol in a high-pressure kettle, and carrying out hydrothermal reaction for 1-3 days at the temperature of 180-200 DEG C; and sequentially carrying out centrifugation, water washing, alcohol washing and drying on the reactant to obtain the CsxWOyFz powder. The preparation method provided by the invention has the advantages of no need for high temperature hydrogen reduction, simple process, low cost, little toxicity and benefit of scale production and practical application. The CsxWOyFz powder prepared by adopting the method has the advantages of excellent visible light transmission performance and near infrared shielding performance and broad application prospect in the aspects of light transmitting and heat insulating of buildings and automobile window glasses.

Production for anhydrous wolframic acid powder is carried out by: adding ammonium salt equal to ammonium wolframate mass 5%-90% with (NH4)2WO4 solution as raw material, adding organic acid equal to ammonium wolframate mass 10%-85%, agitating, pouring into strong acid at temperature 40deg.C- 90deg.C, agitating to obtain yellow ortho-tungstic acid gel, putting the ortho-tungstic acid gel into agitating drier, and incinerating at temperature 100deg.C-500deg.C for 1- 4hrs to obtain the end product nanometer WO3. Its advantages include low cost, simple process and no pollution.

There is described a method of making a nanocrystalline tungsten powder that comprises: (a) heating a tungsten-containing material in a reducing atmosphere at an intermediate temperature of from about 600° C. to about 700° C. for an intermediate time period; the tungsten-containing material being selected from ammonium paratungstate, ammonium metatungstate or a tungsten oxide; and (b) increasing the temperature to a final temperature of about 800° C. to about 1000° C. for a final time period.

To provide a laminated structure for shielding against solar radiation having high solar radiation blocking characteristics with low manufacturing costs. Fine particles 11 functioning to block solar radiation are obtained by firing tungstic acid under a reductive atmosphere, a liquid dispersion to form a solar radiation blocking material is prepared by crashing and dispersing treatment of the fine particles, a polymer base dispersing agent, and solvent, and thus prepared liquid dispersion to form a solar radiation blocking material is added to vinyl resin, which is molded into a sheet shape to obtain an intermediate film 12. Thus obtained intermediate film 12 is sandwiched between two sheets to be laminated selected from sheet-glass or plastic to obtain an intermediate layer 2, which is heated and bonded each other to prepare a laminated structure for shielding against solar radiation.

The invention belongs to the field of semiconductor catalysis, and discloses a preparation method of a bismuth trioxide-bismuth tungstate heterojunction photocatalyst. The method comprises the steps of compounding bismuth trioxide and bismuth tungstate with the molar ratio being 0.1:1 to 0.5:1, so as to form a heterojunction structure, and ensuring that bismuth trioxide is loaded on the surface of bismuth tungstate. According to the method, bismuth nitrate and ammonium metatungsten are taken as raw materails, and the bismuth trioxide-bismuth tungstate heterojunction photocatalyst is formed by one step through a solvothermal method. The preparation method is simple, the synthesis period is short, and a formed sample is high in purity and has a typical p-n heterojunction structure, can effectively restrain the compounding of photo-induced electron and holes, promotes the separation of photon-generated carriers, has the characteristics of high activity and wide spectral response, and is of great importance.

The invention relates to a method of mensurating the content of chrome in tungsten matrix which is added with the chrome and vanadium separately or synchronously. The method is characterized in that a sample is melted by sodium dioxide and is soaked in hot water; meanwhile, the sodium dioxide is also used as oxidant to oxidize the chrome into high valence chrome; ammonium bifluoride is used for complexing main body tungsten and avoiding tungstenic acid cementing out; the whole analysis process avoids the occurrence of precipitation and opacification; titration can be carried out under completely limpid and transparent state; and titration result is exact and reliable. The limpid and transparent solution during the titration is very important to the accuracy of titration analysis. The solution is always limpid and transparent during the whole mensuration process, thereby ensuring that the interference of the vanadium is eliminated exactly and quantitatively when the chrome is mensurated. After the interference of the vanadium is oxidized by potassium permanganate, ferrous ammonium sulphate standard solution is used for titrating to eliminate by a subtraction method. The mensurating method ensures that the mensuration is carried out under the completely limpid and transparent state, and the method eliminates the interference of the vanadium completely and quantitatively and improves the accuracy and the speed for detecting the content of the chrome in the tungsten matrix which is added with the chrome and the vanadium separately or synchronously.

The invention discloses a wear-resisting tungsten alloy and a preparation method thereof. The method includes the steps that firstly, aluminum nitrate, citric acid and ammonium metatungstate are adopted as raw materials and prepared into solutions, the solutions are mixed, a sol-gel reaction is carried out, and gel is dried and roasted to obtain Al2O3 / WO3 mixed powder; then, the Al2O3 / WO3 mixed powder is subjected to hydrogen reduction to obtain Al2O3 / W mixed powder, and then the Al2O3 / W mixed powder is subjected to ball milling with a planetary ball mill; finally, sintering is carried out to obtain the tungsten alloy. In the prepared tungsten alloy material, both the alumina grain size and the tungsten grain size are very small, the tungsten grain size is 0.5-2.1 micrometers, and the alumina grain size is 50-200 nanometers. The recrystallization temperature of the prepared tungsten alloy can reach 1600 DEG C or so. Compared with a pure tungsten material, microhardness is improved by 3-20%, and high-temperature wear resistance is improved by 5-15%.

This invention provides a method for highly efficient catalytic conversion of cellulosic raw materials to glycols. In the process, cellulosic compounds such as crop stalk, wood powder and etc., as feedstock are subjected to one-step catalytic conversion with a ternary composite catalyst composed of organic acid or inorganic acid which does not contain tungsten, a transition metal from Groups 8, 9 or 10 such as iron, cobalt, nickel, ruthenium, rhodium, palladium, iridium, and platinum, or a mixture thereof, and a tungsten oxide, a tungsten sulfide, a tungsten chloride, a tungsten hydroxide, tungsten bronze, tungstic acid, a tungstate, a metatungstate acid, a metatungstate, a paratungstate acid, a paratungstate, a peroxotungstic acid, pertungstate and heteropoly tungstate, or a mixture thereof. The reaction is carried out under hydrothermal conditions at a temperature between 120-300° C. with hydrogen pressure between 1-13 MPa.

The invention discloses a method for adjusting the morphology and the size of a tungsten oxide by using carbon nanotubes, and belongs to the technical field of tungsten-based nano materials. The method comprises the following steps: by taking the carbon nanotubes as a template and a morphology adjusting agent, ethylene glycol as a dispersing agent and a tungsten metal salt as a tungsten source, adding an acid solution into a reaction system, enabling a tungstic acid to nucleate and grow up on the surface of a carbon nanotube bundle, so as to form a carbon nanotube / tungstic acid compound; putting the compound into a high-temperature reaction area, and performing thermal treatment in the presence of an inert atmosphere. The method is simple in preparation process, concise in process control and wide in application prospect, the raw materials are easy to obtain, and the morphology and the size of the prepared tungsten oxide can be regulated and controlled.

The invention belongs to the field of powder production in powder metallurgical industry, and relates to a method for preparing microfine spherical tungsten powder. The method is characterized in that concentrated sulphuric acid is comprehensively used as a precipitating agent and a dispersing agent for ammonium tungstate to form a precipitate of tungsten acid; and the precipitate is dried and reduced by hydrogen to form tungsten powder. The method comprises the following technological steps: a saturated solution ammonium tungstate and a dispersing agent are stirred by ultrasonic waves to be mixed uniformly, wherein the dispersing agent is BYK-154, BYK-163, sodium dodecyl sulfate, or dodecyl sodium sulfate, and the amount of the dispersing agent added is 1 to 2 percent of that of the solution of ammonium tungstate; concentrated sulphuric acid is added into the mixture by the stirring of ultrasonic waves, wherein the volume ratio of the concentrated sulphuric acid to the solution of ammonium tungstate is (15-20):100; and the precipitate is formed during stirring, filtered off, dried, crushed and placed into a hydrogen reduction furnace to be reduced to obtain microfine spherical tungsten powder with a granularity of between 1.2 and 2.8 micrometers, wherein the reduction temperature is between 680 and 720 DEG C. The method simplifies the production technology for producing tungsten powder and can reduce production cost of spherical tungsten powder obviously.

The invention discloses a tungsten trioxide / carbon nitride / bismuth oxide double-Z type photocatalyst and a preparation method and application thereof. The tungsten trioxide / carbon nitride / bismuth oxide double-Z type photocatalyst is prepared by using carbon nitride as a carrier, and modifying tungsten trioxide and bismuth oxide to the carbon nitride. The preparation method comprises the following steps of mixing bismuth nitrate pentahydrate, tungstic acid and melamine, grinding, and calcining, so as to obtain the tungsten trioxide / carbon nitride / bismuth oxide double-Z type photocatalyst. The tungsten trioxide / carbon nitride / bismuth oxide double-Z type photocatalyst has the advantages that the light absorption ability is strong, the photo-induced electron and cavity separation efficiency is high, the photocatalysis activity is high, the oxidation and reduction ability is strong, and the like; the synthesizing method is simple and convenient, the cost of raw material is low, the energy consumption is low, the consumption time is short, the conditions are controllable, and the like; the photocatalyst is suitable for continuous large-scale batched production, and is favorable for industrialized utilization; the double-Z type photocatalyst can be used for degrading antibiotic wastewater, the application method is simple, the degrading efficiency is high, the abrasion-resistant property is strong, the photocatalysis property and the stability are good, and the good practical application prospect is realized.

The present invention belongs to the field of chemical technology, and is a kind of supported tungstic acid catalyst for multiphase catalytic oxidation and synthesis of glutar aldehyde from cyclopentene. The catalyst has TiO2 microball of unique structure synthesized through homogeneous alcohol-hydrothermal process as the carrier and WO3, prepared with ammonium tungstate / tungstic acid and assistant and through dissolving in water, adding TiO2 microball, evaporation, stoving, roasting, activating and other steps, on the TiO2 carrier. The WO3 / TiO2 catalyst has very high gluter aldehyde selectivity and yield and extremely high industrial application value.

The invention discloses a treatment method for high-phosphorus high-molybdenum complex scheelite. The treatment method includes the following steps that phosphorus minerals in the high-phosphorus high-molybdenum scheelite are selectively leached out through nitric acid, and through filtration, a mixed solution of the high-molybdenum scheelite and phosphoric acid nitric acid containing molybdenum is obtained; sulfuric acid is added to the solution for decalcification treatment; after decalcification, NH4+ is supplemented into the solution to prepare ammonium phosphomolybdate trihydrate crystals, and the ammonium phosphomolybdate trihydrate crystals are subjected to the working procedures of ammonia neutralization, purification and acid precipitation to prepare ammonium tetramolybdate; crystallized mother liquid is subjected to the working procedures of neutralization, vacuum evaporation, pelletizing and drying to prepare nitric phosphate; the high-molybdenum scheelite subjected to nitric acid intensified leaching dephosphorizing treatment is adopted and tungstic acid obtained through filtration is subjected to ammonium hydroxide solution conversion and purification impurity removal to prepare ammonium paratungstate; and the nitric acid is supplemented into a leaching solution and the dephosphorizing working procedure of the high-phosphorus high-molybdenum scheelite is executed again. By the adoption of the treatment method, the high-phosphorus high-molybdenum complex scheelite can be treated, tungsten, molybdenum and phosphorus in the minerals are comprehensively recycled, treatment equipment is simple, operation is convenient, and industrialization is easy to achieve.

The invention relates to a tungsten trioxide nanosheet and a tungsten trioxide nanosheet-doped gas sensor. A preparation method for the tungsten trioxide nanosheet comprises the following steps of reacting a raw material tungstic acid (WO3.xH2O) with alcohol amine to obtain an alcohol amine intercalated tungstic acid layered compound, performing oxidation by using concentrated nitric acid to remove the alcohol amine, and performing heat treatment to obtain the tungsten trioxide nanosheet. According to the tungsten trioxide nanosheet and the tungsten trioxide nanosheet-doped gas sensor, a preparation process is simple and easy, and requirements on equipment are low; the tungstic acid with a micron dimension or a millimeter dimension is used as the raw material, so that the aims of realizing stable batch production and remarkably lowering the preparation cost of the tungsten trioxide nanosheet are fulfilled; tungsten trioxide nanosheet-doped gas sensor with quick response to gas such as hydrogen sulfide can be obtained by doping the tungsten trioxide nanosheet with a trace of noble metal.

The invention relates to a method for extracting tungsten and molybdenum through acid decomposition of high-molybdenum scheelite. The method comprises the following steps: leaching the high-molybdenumscheelite with an acid solution, and extracting a leachate to extract molybdenum; extracting a leaching residue with hydrogen peroxide to obtain a solution containing peroxotungstic acid and peroxymolybdic acid, and heating or introducing SO2 to obtain tungstic acid and a solution containing the peroxomolybdic acid; extracting the tungstic acid with hydrogen peroxide, and heating or introducing SO2 to obtain tungstic acid and a solution containing the peroxomolybdic acid; repeating for several times till pure tungstic acid is obtained; preparing tungsten trioxide or tungsten powder from the pure tungstic acid; and heating or introducing SO2 into the solution containing the peroxomolybdic acid, dissolving obtained molybdic acid in a hydrogen peroxide solution to prepare a peroxomolybdic acid solution, and performing ultrasonic spraying pyrolysis to prepare molybdenum trioxide powder or molybdenum powder. By the method, the separation effect is good and the operation process is simple and easy to control, so that the method is easy to popularize and apply industrially.

The invention discloses a method to test Sildenafil citrate and its ramifications. It contains steps: (1) Color reaction. Make color reaction of test sample with bismuth potassium iodide, silico-tungstic acid and Hager's reagent to observe result. (2) Result estimation. If above three color reactions appear deposit, there are Sildenafil citrate and its ramifications in test samples. If just one, two or none color reaction appear deposit, there is no Sildenafil citrate and its ramifications in test samples. The method has merits of quick, simple, strong property, high accuracy, extensive application and testing range.

The invention belongs to the field of resource recycling, and particularly relates to a method for recovering metals copper, tungsten and molybdenum by use of APT (ammonium paratungstate) waste slag. The invention discloses a method for recovering copper, tungsten and molybdenum by the use of APT waste slag, and comprises the following steps of: (a) powder grinding; (b) copper separation and recovery through alkaline leaching; (c) molybdenum recovery through acid leaching and precipitation purifying method; and (d) tungsten recovery through an ion exchange method. The method provided by the invention has the beneficial effects that (1) the method can recover copper, tungsten and molybdenum in the APT waste slag so as to effectively reduce resource waste and improve the utilization rate of resources; (2) the recovery rate of copper, tungsten and molybdenum is as high as about 95%; (3) by recovering the elements copper, tungsten and molybdenum in waste slag, the economic benefits of an enterprise can be increased; (4) the method can adopt the existing equipment of an enterprise without adding equipment, and thus can effectively reduce the investment in equipment and lower the cost; and (5) all solutions generated by the method are treated in subsequent processes, thereby avoiding emission problem and causing little environmental pollution.