Improved Coking Resistance of “Intelligent” Ni Catalysts Prepared by Atomic Layer Deposition

Conformal CaTiO3 films were deposited onto MgAl2O4 by atomic layer deposition (ALD) and then examined as “intelligent” catalyst supports for Ni in the steam and CO2 reforming of methane. CaTiO3 films (1 nm) were characterized by scanning transmission electron microscopy and XRD and shown to be stable to at least 1073 K. Catalysts with 1 and 20 wt % Ni were studied, and it was found that, following calcination at 1073 K, the Ni-CaTiO3/MgAl2O4 catalysts required high-temperature reduction to achieve activities comparable to that of their Ni/MgAl2O4 counterparts. However, the Ni-CaTiO3/MgAl2O4 catalysts exhibited dramatically improved tolerance toward carbon-whisker formation. The carbon content on the 1 wt % Ni catalyst on CaTiO3/MgAl2O4 was small even after heating the catalyst in a dry, 10% CH4–90% He mixture at 1073 K for 12 h. Possible mechanisms for the high carbon tolerance of the perovskite-containing catalysts are discussed.