Supported Tungstophosphoric Acid Catalyst Preparation

supported tungstophosphoric acid catalyst image

Theoretically, many of the carriers found at present can be used as the carriers of tungstophosphoric acid, but most of them use oxidants as the carriers of oxidants or are easy to decompose when alkali is azeotropic. At present, SiO2, HZSM-5 molecular sieve, Y-type molecular sieve, HP, HMS molecular sieve, worm like molecular sieve, activated carbon, silica gel and so on are the main carriers of phosphotungstic acid catalyst.

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Cadmium Tungstate Single Crystal Growth by Crucible Descent Method

cadmium tungstate single crystal image

Cadmium tungstate (CdWO4, CWO) single crystal is a scintillation crystal material with excellent comprehensive properties, which can be widely used in nuclear medicine imaging, safety inspection, industrial CT, oil logging, high energy physics and other technical fields, especially in medical X-CT, container inspection system. Up to now, it has been reported that the single crystal of cadmium tungstate has been grown by Czochralski method at home and abroad. It is very difficult to grow high-quality large-scale cadmium tungstate single crystals. The main problem is that the optical transmittance of the grown single crystals is not uniform at the beginning and the end, the repeatability of the single crystals grown in different batches is poor, and there are many crystal defects such as cracking, inclusions, color centers, etc. 

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Scheelite Decomposition by Sodium Silicate

scheelite decomposition image

Sodium hydroxide decomposition is the main process for tungsten mineral raw materials. In the alkaline system, phosphorus, arsenic, silicon, molybdenum, tin and other elements contained in the mineral are leached to varying degrees and become the main impurities in the crude sodium tungstate solution. Some scholars have found that when sodium hydroxide decomposes tungsten ore, the calcium content of raw materials is beneficial to inhibit the leaching of impurities such as phosphorus, arsenic and silicon, and the leaching rate of these impurities decreases with the increase of calcium content.

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What is Halotungstate

halotungstate image

Halotungstate is a kind of tungstate which is mainly composed of oxyhalide, it is a new type of visible light response photocatalyst.

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Co-doped Barium Tungstate Thin Film Preparation by Magnetron Sputtering

co-doped barium tungstate thin film preparation image

Tungstate is an important inorganic functional material, which has broad application prospects and development potential. It can be used as scintillation crystal, luminescent matrix material, photoluminescent material, gas sensitive material, catalyst, etc. Tungstate is a typical self activating luminescent material. Its luminescent source is WO42- complex ion. Under the excitation of X-ray, ultraviolet light and cathode ray, they can emit high-efficiency fluorescence. According to the different structure, tungstate can be divided into two types: scheelite type and wolframite type. In tungstate, calcium tungstate, lead tungstate, zinc tungstate, cadmium tungstate and barium tungstate are important inorganic materials.

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Photoelectric Functional Material - Barium Tungstate

barium tungstate image

Barium tungstate (BaWO4) is one of the divalent metal tungstate, which is an important photoelectric functional material. Barium tungstate crystal is a promising Raman laser crystal due to its stimulated Raman scattering. Barium tungstate crystal can be used in all solid state lasers, and it is possible to design it to emit radiation in special spectral region. Barium tungstate crystal has important application value in many fields, such as photoelectricity, medicine, spectroscopy, because of its special characteristics of photoluminescence, thermoluminescence and stimulated Raman scattering.

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Negative Thermal Expansion Material Zirconium Tungstate Research Progress

negative thermal expansion material zirconium tungstate research progress image

Thermal expansion and cold shrinkage of materials is a common phenomenon in nature, but some materials are contrary to this. The coefficient of thermal expansion is negative, that is, the volume decreases with the increase of temperature, which is called negative thermal expansion material (NTE) or thermal shrinkage material. ZrW2O8 is a recently discovered material with large isotropic negative thermal expansion in a wide temperature range (0.3k to 1050k). The simple cubic ZrW2O8 was first synthesized in 1959 and found to have NTE effect. At that time, it was known that its crystal was cubic structure, but the atomic position was not determined, and its unique NTE performance did not attract attention. Until 1996, the a w sight research group of Oregon State University reported the crystal structure type of the material in science, and the research on ZrW2O8 started. It's the beginning of attention.

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Zirconium Tungstate Preparation

zirconium tungstate preparation image

Zirconium tungstate has a formula of Zr(WO4)2 and a molecular weight of 586.9. It is a negative thermal expansion material with excellent performance. It has negative thermal expansion performance in the temperature range of 0.3-1050.0k.

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Low-grade Tungsten Treatment Process and Equipment

scheelite image

The low-grade tungsten concentrate produced by some tungsten concentrators can not meet the quality standard, the grade of WO3 is 5-30%, and the content of other impurities is also relatively high. It is mainly low-grade tungsten slime concentrate, tungsten tin medium ore, tungsten bearing iron sand and other refractory tungsten containing intermediate products. These products are sold in the form of sodium tungstate or scheelite, ammonium paratungstate, tungstic acid or tungsten trioxide through chemical beneficiation, and other useful components are comprehensively recovered from the leaching slag. The principle process of chemical beneficiation of low-grade tungsten mineral raw materials can be divided into material preparation, etc.

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High Purity Ammonium Metatungstate Crystal Preparation by Nanofiltration

ammonium metatungstate image

With the rapid development of petroleum processing industry, the research and development of tungsten catalysts have been paid more and more attention. The active component of the catalyst, tungsten trioxide, is used as catalyst carrier, such as spherical silicon and aluminum oxide, which are made by leaching and pyrolysis of ammonium metatungstate. This is the direct driving force to promote the development of AMT in recent years. There are many processes for AMT production. Nanofiltration technology is a membrane separation technology separated from reverse osmosis technology, which is the continuation and development branch of ultra-low pressure reverse osmosis technology.

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