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Material absorbed on surface
11-17-2014, 12:51 PM (This post was last modified: 11-17-2014 12:51 PM by i.kovacs.)
Post: #1
Material absorbed on surface
We have received this question to askthechemist@thalesnano.com:

I would like to ask about some details regarding H-Cube (the original model) reactor. I have successfully used it for number of hydrogenation reactions. However, I found that in some cases, significant amount of material remains inside the machine, probably being adsorbed on the catalyst. It usually happens if 10% Pd/C is employed, Pd/alumina did not how such behavior. This phenomenon is observed if compounds are hydrophilic (mostly PEG derivatives) and used in small quantity (up to 70 mg).I tried washing the catalyst with different solvents, from methanol to cyclohexane, but it seems that the compound remained deposited inside. If there is a good method for recovering such ‘disappearing compounds’, as well as any special procedures how to run small scale reactions, I would appreciate if you let me know.

You are right about the explanation. The charcoal has a very high specific surface and it may absorb the hydrophilic materials. It is almost impossible to wash out the materials from the surface, the only thing which may be useful is to use some acid in the reaction mixture, which decreases its’ absorption ability.
Nevertheless, there is a good solution to react a small amount of starting material. We have a catalyst series called MicroCart, where the catalyst bed is reduced to avoid the loss of your starting material/product. The MicroCart contains two pieces of PTFE spacers which reduces the bed length to 8 mm (1/3 of the original).
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Material absorbed on surface - i.kovacs - 11-17-2014 12:51 PM

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