A magnetically stabilized bed (MSB) reactor with amorphous nickel alloy catalyst (SRNA-4) was used for purification of caprolactam. The effects of various operating conditions on the hydrogenation were investigated, and the lifetime of SRNA-4 catalyst was also examined. A mathematical model of MSB reactor for hydrogenation of caprolactam solution was established. The experiment results show that the PM number (permanganate number) of caprolactam aqueous solution can be increased from 50 s to more than 2000 s through MSB hydrogenation process, and the lifetime of SRNA-4 catalyst is more than 3200 h. The catalyst consumption is reduced by 60%, as compared with that of the slurry reactor. (C) 2003 Elsevier Science B.V. All rights reserved.