As per my experience, the leaching of catalyst can be measured by using a hot filtration method. We should filter out the catalyst from the reaction mixture at the stage of 50% conversion. If reaction further proceed, that means leaching of catalyst happened. On other hand, if there is no further progress in the reaction that indicates there is no leaching.
We have performed hot filtration test for reaction, where we used CuI@carbon sphere catalyst. We did not observe further progress of reaction after filtration. Is it compulsory to analyze the filtered reaction mixture by ACP-AES to confirm the absence of metal catalyst.
Dear Prof EI-Molla,
How can I perform this experiment. What it indicates, if any change or no changes in acidity of the solution ?
Can you please give me more details with related reference.
Thanks
Rajesh
Hi Chinna, a straight forward procedure would be to analyse the reaction solution for the metal used as catalyst, as the reaction progresses. Do this using the same catalyst for up to 5 reaction cycles with an ICP or AAS (depending on the concentrations you envisage). You may then attempt a homogeneous reaction with with the maximum concentration of metal you observe from the analyses to see if there's any homogeneous contribution to your reaction as a result of a possible leaching.
In most cases, catalyst leaching is a slow process and the leached amount in one circle may not be sufficient enough to create a significant equilibrium shift especially in test tube experiments. Using ICP measurement of the filtrate maybe a good way but in the absence of this technique one can easily use wet chemistry techniques to qualitatively identify the leached catalyst. Chose the detection method to target the most vulnerable species in your catalyst and if possible change the working environment to be very harsh than normal.
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