I have two catalyst. The catalyst which has high catalytic activity experimental ,shows low TOF (s-1) and high activation energy. i am calculating the TOF by formula {conversion (converted moles/s/gcat)/ Ns} is number of sites , which i calculated from TEM and using dispersion formula i calculated the exposed Pt metal surface area.
ٍA possible reason behind this behavior may be concern with surface topography. Sometimes, catalytic activity decreases when the roughness of the solid surfaces increseses.This may due to a greater number of active cites on a rough surface. High roughness usually causes decreasing of contact angle. Contact angle plays an important role in the mass transfer. Surface roughness increase might increases the wettability of the solute and hence decreases both the contact angle and the hydrophobicity.
Thanks for your valuable answer but if i can have some references it will support our argument
I agree with the point of view of Dr. Hassan, and I added, the method with the additions that used to load Pt on SiO2 and TiO2, then the used temperature of calcination, all these parameters lead to increase a rough of catalyst surface with decreasing the activity......
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