Dear All
Please, What is the cause of pale yellow color of TiO2 prepared by sol gel ?
I prepared it as following:
10 ml Titanium isopropoxide + 8 ml of EtOh and add this solution to solution B (1.4 ml HCl and 6 ml water) dropwise and then the gel was formed in few hours left for 1 d, then drying at 80 C for 3 hours followed by calcination at 450 C for 3 hr.
My gel is yellow pale and after drying and calcination I obtain yellow pale titanium dioxide catalyst
Regards,
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The titanium dioxide sol-gel solution or gel material can be transparent or yellow color depending on operation conditions.
I suggest you read this article : http://www.google.com/patents/US20050265918.
It may be due to incomplete combustion of the organic materials and also can be related to formation of rutile phase.
This case may be due to formation of oxygen vacancies during heat treatment .You need to analyze your catalyst by XPS technique to reveal oxidation states of titanium
Thanks all
The color of TTIP is yellow and during solubilsation of TTIP in ethanol it forms yellow solution.
the gel formed after hydrolysis and condensation is yellow pale as described in the first photo.
I think the quantity of water is so little ??? And according to several works the rutile phase is obtained when temperature of calcination exceed 550 C Mr Mohammed???
Thanks
Hello, Allouche,
About the point of evaporating organic materials, I believe the 450oC are enough to eliminate the ones you used as precursors.
Answering your question in the comments, the temperature of phase transformation depends on the obtaining method. The transition from anatase to rutile may take place in a range of temperature from 400 to 1000oC, so, your powder with calcination at 450oC may be in the transition.
Hope it may help you,
Miguel
I also prepared TiO2 sol yesterday (18/12/2018) the solution is yellow.
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