As far as I know, the TGA results should show decreases in weight but my spent catalyst (Ni/ZrO2-SiO2) weight increased.
I know weight gain should only happen if the samples react with the atmosphere: oxidize. But then the graph shows a straight line (100%) until 400-500 ˚C and then it started to increase. No decreases at all.
I suspect that the instrument needs proper calibration. But then, only for spent catalyst have this problem. All the fresh catalysts showed a standard result in which the weight decreases. So I don't think it's the instrument's fault.
Can quartz wool or glass wool increases in weight when temperature increases?
I suspect probably a tiny bit of quartz/glass wool was mixed with the catalyst.
The conditions that I used were 30˚C to 800˚C with a heating rate of 10˚C /min and used air as the carrier gas.
Glass wool or any other mineral wool cannot gain weight when calcined in air. However, there is a component in your catalyst - nickel, which oxidizes in air and adds weight.
Vadim Verlotski Thanks for answering!
But is it possible if the catalyst weight didn't decrease at all?
Is it possible that the spent catalyst has no moisture content or coke deposits?
Dear Abdul,
I don't know what condition your spent catalyst is in. It may well be that there is neither moisture nor carbon there, if the hot catalyst was blown with air before extraction. An indisputable fact is that weight gain can only occur due to the oxidation of the metal component - nickel.
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