The researchers have proposed a preparation method of ammonium metatungstate. And the ammonium metatungstate (AMT) prepared by this method can be used as a catalyst for petroleum cracking.
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A Preparation Method of Ammonium Metatungstate
Step One: Dissociation. APT is heated and calcined in the rotary furnace at a temperature of 180-220 °C for 50-70 min to prepare a dissociated material.
Step Two: Leaching. Send the dissociated material to the reaction kettle, add 1-4 mol/L of dilute nitric acid for reaction, control the pH value to 3-5, and when the WO3 content in the solution reaches 150-200 g/L, stir for 10-20min to obtain AMT solution.
Step Three: Clarification and filtration. AMT solution was allowed to stand and age for 1-2 h in the first clarification tank, and then the clarified solution was filtered with a first bag filter to obtain filtrate A.
Step Four: Concentration, clarification and filtration. Filtrate A is heated and concentrated in the concentration reactor. The concentration temperature is 60-70 °C. The pH value of the filtrate A is adjusted with ammonia water to 3-4. When the specific gravity of the filtrate A reaches 1.6-1.8, the filtrate A is sent to the second clarification tank, let stand and age for 2-3h, and then filter the clarified solution with a second bag filter to obtain filtrate B.
Step Five: Spray drying. Filtrate B was spray dried by a spray drying tower to obtain ammonium metatungstate.
