Hydrogen reduction is the earliest method for preparing rare metals such as tungsten and molybdenum. And the hydrogen reduction of tungsten hexachloride is the most noticeable method in the preparation of ultrafine tungsten powder at home and abroad.

The researchers proposed a method for preparing high purity tungsten hexachloride, which requires the following steps: raw material pretreatment, tungsten hexachloride preparation, tungsten hexachloride refining, condensation reception and tail gas treatment.

What is tungsten hexachloride? Tungsten hexachloride is the chemical compound of tungsten and chlorine with the formula of WCl6. It shows dark blue or blue violet appearance, and exists as a volatile fine powder under standard conditions.

Ammonium metatungstate (AMT) is an important tungsten-containing compound that can be used as a catalyst in petroleum cracking, organic synthesis, and nitrification reactions. Nowadays, with the rapid development of petroleum refining and petrochemical industries, AMT is more and more popular. Therefore, how to obtain AMT with advantages of low impurity content, stable quality, good solubility, high WO3 content and low cost has become the priority of the current task.

Ammonium metatungstate catalyst is a new type of catalyst with the characteristics of strong activity, high selectivity, long service life, good water solubility, uniform distribution of active components on the carrier, and large specific surface area. Therefore, it has attracted much attention form many researchers, and its applications are expanding.

Ammonium metatungstate decomposition temperature varies with the degree of completion of the decomposition reaction. This also means that ammonium metatungstate will produce different products at different decomposition temperatures.

Ammonium metatungstate (AMT) is a white crystal powder or yellowish crystal powder with good water solubility, which can be used for preparation of diesel hydrogenation catalyst. For example, the researchers have proposed a method for preparing FCC diesel hydrorefining catalyst by using ammonium metatungstate as an active component.

Ammonium metatungstate (AMT) is a white or light yellow crystalline salt that is soluble in water. Generally, ammonium metatungstate solubility refers to the solubility of AMT in water. The data shows that at 20 °C, the solubility of AMT in water is 303.9g, and its solubility increases with increasing temperature. Besides, the aqueous solution of AMT is quite stable.

How to prepare ammonium metatungstate crystal? Or how to prepare AMT crystal? There are various preparation methods, such as thermal decomposition method, neutralization method, solvent extraction method, tungstic acid method, ion exchange method, etc.

How to prepare high purity ammonium metatungstate crystal? The researchers proposed a method for preparing high-purity AMT crystals - neutralization-nanofiltration coupling process. This method can not only obtain a high concentration AMT solution to reduce the cost for the subsequent crystallization process, but prepare AMT with less impurity content to ensure the preparation of high purity ammonium metatungstate.