Why does the morphology change with the impregnation of the bulk vanadium phosphorous oxide (VPO)? What happens? I have synthesized the Mo-VPO materials in wetness-impregnation method and calcined at 450°C for 6 h.
May be its because of temperature or time effect at the process of calcined, you can decrease time, or decrease temperature.
Dear Mr. Iqbal , Thank u very much for ur reply. But I need a real inorganic mechanism how the morphology changes. Whether there is polymerphic MoO3 formed on the material surface or some other reason.
this can be also due to the impregnation procedure. you can find it. run one blank reaction without adding Mo precursor and calcined it. see the morphology.
I believe the morphogy of the resulting solid depends very much on the physical condition under which it was generated. Have you tried reproduced your rosette morphology? Slight variation in condition may result in different structure and diferent morphology. It will be difficult to formulate a mechanism by which the morphology of a particular substance changes. Then again the incorporation of Mo becomes a totaly different phenomena. What sort of morphology results will ofcourse depend on the nature of the element and again the physical condition under which it is obtained. Calcination is not a process which you can have control over. The rate of heating and the rate of cooling will also affect the overall appearance of the final solid. I have not come across anyone explainging these phenoma based on any solid theory.
Dear Prof. Adam
Thank you very much for your remarks on the morphology change of my catalyst. It cleared my doubt.
Thanking you again
Regards:
Gobind
Hi Gobinda,
Following on Farook's comments, I would also like to propose a couple of blank tests. I do not know how you prepared the VPO. Did you try a blank test on the VPO?
On one side, you may try to expose it to the same temperature treatment you did to the impregnated VPO and see it that treatment has an effect.
A second option is to do a wetness impregnation on VPO without moly, only water. And follow the drying-calcination treatment you made.
These may tell you is already the temperature treatment, or water impregnation + temperature treatament has an effect on VPO
regards,
Miguel
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