Ammonium Paratungstate Purification from Complex Scheelite Ore

ammonium paratungstate image

Tungsten ore is mainly scheelite. The world's scheelite accounts for more than 2/3 of total, and China accounts for 72.1%. Some scholars have improved the method of using ammonium sulphate to decompose scheelite to prepare ammonium partrungstate.

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High Purity Phosphotungstic Acid Preparation

high purity phosphotungstic acid image

Heteropoly acid is one of the most active catalysts in acid catalytic reaction and redox reaction. Phosphotungstic acid H3PW12O40•nH2O is the most widely used in heteropoly acid. The purity of phosphotungstic acid directly affects the conversion rate of the catalytic system. Therefore, the preparation of high purity phosphotungstic acid is especially important.

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SCR Waste Catalyst Cleaning and Recycling

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In general, SCR catalyst must be replaced after three years, because the waste catalyst contains a large number of metal elements, improper treatment will cause pollution to the environment. The waste catalyst contains high value added metals such as titanium, tungsten and vanadium.

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How to Coat the Tungsten Substrate

tungsten substrate coating image

Tungsten coated materials can effectively improve the comprehensive performance of tungsten substrate materials, such as oxidation resistance, wear resistance, sweat stain resistance and colourful coloring. Generally, the coated tungsten materials are obtained by CVD or PVD method. The preparation process is more complex and the production cost is higher, and the density of the coating is poor, the thermal matching between the coating and the substrate is poor, and the structure of the coating is difficult to control. The main contents of the new technology are as follows:

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Carbon Nanotube Supported Platinum Electrocatalysts Coated with Titanium Tungsten Oxide

titanium tungsten oxide image

Carbon supported platinum catalysts are regarded as ideal fuel cell catalysts. However, the interaction between the carbon carrier and platinum is weak, the carbon carrier is easy to corrode. The nano platinum particles can easily migrate on the surface of the carrier, grow up and even lose, which leads to the degradation of the catalyst activity, and eventually leads to the shorter service life of the fuel cell.

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Tungsten Doped Vanadium Dioxide

vanadium dioxide image

Tungsten doping is a promising and effective way to reduce the phase transition temperature of vanadium didioxide. Doping can improve the electrical properties of vanadium dididioxide thin films, reduce the square resistance of the films, and improve the resistance temperature coefficient of the films. Common methods of doping include evaporation, ion implantation, sol-gel and magnetron sputtering.

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Nano Tungsten Carbide Preparation Process

nano tungsten carbide image

The preparation technology of nano cemented carbide is very active. The preparation of nano cemented carbide must first prepare nano tungsten carbide powder with excellent properties. At present, there are methods mainly including direct carbonization, gas phase reaction, high frequency plasma, microwave induction plasma, spray conversion, chemical precipitation and high energy mechanical ball milling.

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Enhanced Version Prepare Nano Tungsten Trioxide with Hydrothermal Method

prepare nano tungsten trioxide with hydrothermal method image

Tungsten trioxide (WO3) is a n type semiconductor material with a band gap of about 2.5 to 2.9eV and absorbable wavelengths of 410 to 500nm. The ordered nanostructured tungsten trioxide has the properties of nanomaterials and prominent quantum effects.

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Recyclable Cerium Phosphotungstate Catalyst

recyclable cerium phosphotungstate catalyst image

A method for the synthesis of methyl laurate by cyclic use of cerous phosphotungstate catalyst is proposed. This method does not produce acid waste water and solid waste. It is a green synthesis process. The steps of synthesis are as follows:

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High Purity Phosphotungstic Acid Preparation Method

high purity phosphotungstic acid preparation image

Heteropoly acid is one of the most active catalysts in acid catalytic reaction and redox reaction. The hydration and esterification of olefin, the etherification of epoxides, the condensation reaction of olefin and aldehyde, alkylation, alkene epoxidation, alkyl alkylation, etc. have good catalytic properties. In heteropoly acid, phosphotungstic acid H3PW12O40 nH2O is the most widely used, its purity affects the catalytic system directly. Therefore, it is especially important to prepare high purity phosphotungstic acid.

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