Abstract
In our previous report, we stated as follows: inhibitor-filmed catalyst can stop the hydrogenation reaction while inhibitor-film is on the metallic surface. However, as soon as the film is desorbed from the catalyst, it regains its activity.
In this report, we have studied about resisting power against acetic acid of the film, which formed on Ni-catalyst. The filmed Ni-catalyst is used for the hydrogenation reaction of acetoacetic acid ester after dipping it in 5% acetic acid solution. From the reaction products, we have observed that the catalyst would not be affected by the acid, so the film could protect metallic surface. We have also tested that filmed catalyst would be able to use in such a reactant as containing 1% of acetic acid by wt., in which non-filmed catalyst would be poisoned giving no catalytic behavior.
Amine-filmed catalyst was protected from the above mentioned two types of acid as acetic acid could not affect its activity. Acid-amide-filmed catalyst lost its activity gradually according to increasing concentration of acetic acid. Mercaptan-filmed catalyst gave some complex phenomenon. Cetyl mercaptan-filmed catalyst, prepared by dipping Ni-catalyst in mercaptan solution of alcohol or of dioxane, regained the activity above certain temperature at which the inhibitor-film was desorbed, but octyl mercaptan-filmed catalyst, prepared as same as above, could not recover its activity. And moreover, dodecyl mercaptan-filmed catalyst could not regain its activity but when it was prepared in alcoholic solution.
