(113d) Ni-Substituted Oxide Catalysts with Oxygen Ion Conductivity for Methane Steam Reforming

Nickel-substituted pyrochlore and hexaaluminate catalysts were studied for hydrogen production from methane steam reforming. The reaction conditions were as follows: T = 750°C, GHSV = 25,000 scc/gcat?hr, S/C = 0.9. Each reaction test was run for 5 hrs. The hexaaluminate catalyst, BaNixAl12-xO19-y, contained 6wt% nickel and was used as the base case. The pyrochlore catalysts, A2NixZr2-xO7-y (A = Mg, Ca, Sr), contained 3, 6, and 8wt% nickel. Further, the pyrochlore catalysts were calcined at three different temperatures (700, 800, and 900°C) to examine the effect, if any, on steam reforming performance. The use of an oxygen-conducting support, gadolinium-doped ceria, was also investigated. The catalyst that provided the highest, and most stable level of hydrogen production was the pyrochlore with A = Sr, a nickel loading of 6wt%, and a calcination temperature of 800°C. Under the reaction conditions given this catalyst provided a product stream with an initial hydrogen concentration of ~54% and a final concentration of 51%. Substitution of nickel into an oxide structure, like the pyrochlore, is believed to provide additional stability under methane steam reforming conditions. Further, the presence of oxygen-conductivity is believed to prevent the formation of deactivating carbon species on the active sites.