DEACTIVATION OF BIMODAL NICKEL-CATALYST FOR STEAM METHANE REFORMING REACTION

A bimodal nickel catalyst calcined at 873 K (B) showed a rapid deactivation in 160 h in the steam methane reforming reaction at an atmospheric pressure; however, that calcined at 1173 K (N) showed little deactivation in 600 h. The amount of deposited carbon in N was five times as much as that in B. In B the Ni crystallite size was close to the mesopore diameter; however, in N NiAl2O4 was formed and the Ni crystallite was smaller than that. The difference of the deactivations was presumed: a carbon block was formed in a mesopore inside wall near the mouth and an opened area of the mouth was reduced. In B a thicker carbon block with the diameter of the Ni particle was formed and much reduced the opened area to the active mesopore.