If nickel hydrogenation catalyst is allowed to remain in contact with the liquid containing a corrosion inhibitor, such as hexadecylamine alcohol solution, the catalyst will be adsorbed on the surface by the inhibitor. The catalyst loses its activity while it is shielded by the inhibitor film, but it revives at the critical temperature of desorption of the inhibitor.
With amine-treated nickel catalyst, the hydrogenation of acetoacetic ester proceeds mainly as the following equation:
CH
3COCH
2COOC
2H
5H
2→ca.190°CCH
3-OHCHCH
2CH
2OH+C
2H
5OH
Butylene glycol is scarecely obtained with nontreated catalyst, because the reaction at lower temperature can easily proceed, producing butanol. So, hydrogenolysis of carbon to carbon bonds seems to be taken place. But with amine-treated catalyst lower-temperature reaction is inhibited and, hydrogenolysis of carbon to oxygen bonds is mainly taken place, producing butylene glycol.
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