Nickel-based bimetallic coated monolith catalysts for hydrogen production by steam reforming of JP-10
JP-10 as a representative polycyoalkane has high energy density and volumetric hydrogen storage capacity, which makes it very suitable for hydrogen production onboard by catalytic reforming. Monometallic Ni and bimetallic Ni-M (M = Fe, Co, and Cu) catalysts supported on γ-Al 2 O 3 were prepared by incipient-wetness co-impregnation method. Effects of the second metal M on the catalytic performance of Ni/γ-Al 2 O 3 for hydrogen production by steam reforming of JP-10 were investigated in a coated microchannel reactor. The catalysts were characterized by N 2 adsorption–desorption, XRD, XPS, TEM, NH 3 -TPD, TG, H 2 -TPR, and Raman techniques. The results showed that the catalytic performance of Ni-M/γ-Al 2 O 3 deeply depended on the second metal M, in which Ni-Fe/γ-Al 2 O 3 was the best in terms of JP-10 conversion (82.9 %), H 2 selectivity (63.9 %), and coke amount (0.091 g coke/g cat. · h) under reaction conditions of 750 °C, 1.0 bar, steam to carbon of 2.4, weigh hourly space velocity of 472 h −1 . The doping of Fe formed highly dispersed Ni 3 Fe alloy crystallite for NFeA catalyst, and the average particle size is about 12.2 nm. Fe facilitated surface migration of Ni 0 species resulting in higher surface concentrations of Ni 0 species, thus enhanced the catalytic activity. In addition, Fe moderated the interaction between the support and nickel oxide particles, and promoted the reducing property of calcined catalysts overall, which ensured excellent resistance to sintering and high activity. The amount of weak and medium acid in the reduced NA catalyst were increased due to the presence of Fe, which improved activity and simultaneously avoided severe carbon formation. After reaction, NFeA catalyst produced much whisker graphite carbon, while the spent NA catalyst mainly generated amorphous carbon. NFeA catalyst maintained good stability over time on stream of 50 h, and severe carbon deposition, rather than the sintering of the active components, was the main cause of the catalyst deactivation. This work may provide important guidance for catalyst design applied to steam reforming of polycyoalkanes.
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