Pyrochlore Tungsten Trioxide Preparation

Pyrochlore tungsten trioxide (WO3 • 0.5H2O) WO6 makes distorted octahedral as structural motifs, building a layered structure with pore ring by a rigid skeleton top corner WO.It can be used as intermediates in the preparation of tungsten oxide, hopefully reducing tungsten process, achieve lye circulation because of its molecular sieve having mesh structure and referral stability in materials science with a wide range of applications in the tungsten smelting field.  Currently, preparing pyrochlore tungsten oxide by hydrothermal has been able to guarantee a certain response rate, but hot water containing sodium tungstate architecture is more complex, limiting the application of the law. Therefore, how to strengthen and optimize the hydrothermal reaction process to prepare pyrochlore tungsten oxide, which is very important to achieve industrialization.

In view of the WO3-soluble sodium tungstate solution, change the hydrothermal system plays the role of pH value, the paper choose tungsten trioxide as additive preparation pyrochlore type oxide, tungsten, and supplemented by carbon dioxide, sodium tungstate solution of oxalic acid pretreatment, in detail study the morphology and response rate solution resulting product under different conditions, the reaction of the various factors affecting the process are analyzed. According to the experimental data, and IR spectrum analysis tools, the reaction mechanism was discussed Hydrothermal pyrochlore type tungsten trioxide.

Experiment indicates:
(1) We use tungsten trioxide alone as an additive to stabilize the pH of the hydrothermal system and gain pyrochlore trioxide products, which shows the reaction rate can reach 80%. And we choose oxalic acid, CO2 to deal with Sodium tungstate , which helps to change the reaction rate, and the reaction time from more than 24h shortened to less than 8h.
(2) It is also capable of producing tungsten trioxide pyrochlore trioxide products in the pH ranges 3.5 to 8.9.
(3) The products obtained have good cubic structure, the average particle size of the particles are about 1μm by XRD, SEM analysis and other means of detection,
(4) We wash with a small amount of diluted hydrochloric acid Na element because of the product is easy to carry elements Na.
(5) The Experiment shows the use of infrared detectors is to prepare the preliminary view W2O72- pyrochlore tungsten oxide growth unit.
 

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