| 摘要 |
<p>Cyclohexanone oxime is prepd. by a recycle process, in which an acidic, buffered aqs. reactant contg. phosphoric acid and/or bisulphate is recycled between a hydroxylamine synthesis zone and a cyclohexanone oxime synthesis zone, and nitrate ions and nitrogen oxide are reduced catalytically with molecular hydrogen and a noble metal catalyst in the hydroxylamine synthesis zone to hydroxylamine, which is utilised in the oxime synthesis zone. The cyclohexanone oxime is separated from the aqs. reaction liquid, and the liquid is contracted in a reaction zone at an elevated temp. with nitrous gases. The recycle liquid from this reaction zone, which is poor in oxime and rich in cyclohexanone, is subjected to a stripping process for removing residual cyclohexanone, and the necessary nitrate ions and nitrogen oxide for the hydroxylamine synthesis are added before the liquid is recycled to the hydroxylamine synthesis zone. Neither cyclohexanone nor oxime are present in the recycle liquid returned to the hydroxylamine synthesis zone, so the poisoning of the noble metal catalyst by these cpds. is avoided.</p> |
