Polymorphic Nanosize Tungsten Trioxide Produced Continuously from Ammonium Paratungstate 2/2

Equipment requirements: fused quartz tube with air inlet and outlet pipe; tubing furnace; ceramic crucible.
Reactants: carbon cloth; ammonium paratungstate (APT); argon.

Specific steps as following:
1. Take out fused quartz tube, place carbon cloth at the end of inner wall of air outlet, and then sent fused quartz tube with carbon cloth traverse in a tube furnace;
2. Heating tube furnace to make sure the fused quartz tube heating up to the  temperature of 1250°C-1400°C, and the heating rate keeps in 50°C/min;
3. Sent the ceramic crucible with APT into the used quartz tube, and keep it in zone of specified temperature, blowing argon with flow lL/min-6L/min;
4. Keep the temperature in the specified value for 40~60min, turn off the inlet and stop blowing argon;
5. Take out carbon cloth to collect polymorphic nanosize tungsten trioxide, and remove out the ceramic crucible;
6. Repeat steps 1-5, to achieve continuous production.
Noted that work as following should be done at each cycle:
1. Clean the fused of quartz tube for removing residual products, if the wall isn’t washed, the contamination of subsequent preparation will be occurred;
2. Place a new carbon cloth around the inner wall of the glass tube;
3. Take the ceramic crucible with APT to temperature constant zone;
4. Inlet argon again.

The advantage of this method is that the size and purity of WO₃ powder can be controlled because of the high purity APT selected; preparation process simplified, shorten production cycle; lower cost and energy consumption. At the same time, the loose degree of the powder generated is really high, and there is no need to broken again.

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