Catalytic activity and characterizations of Ni/K2TixOy–Al2O3 catalyst for steam methane reforming

• The presence of K2TixOy weakened the interaction strength between Ni and the support.
• High loading of K2TixOy led some isolation of Ni from the support.
• Modification of Ni/Al2O3 with K2TixOy enhanced SMR activity.
• Ni/K2TixOy–Al2O3 possessed better SMR stability in the harsh reaction conditions.
• Proper addition of K2TixOy improved resistance to deactivation of the catalyst.

Nickel catalysts supported on the K2TixOy–Al2O3 were prepared by the wet impregnation method for steam methane reforming to produce hydrogen. X-ray diffraction, N2 physisorption, scanning electron microscopy with energy dispersive spectroscopy, the H2 temperature-programed reduction technique, and X-ray photoelectron spectroscopy were employed for the characterization of catalyst samples. The results revealed that the performance of the Ni/K2TixOy–Al2O3 catalysts was comparable to that of commercial FCR-4 for steam methane reforming under the mild condition. In particular, a catalytic stability test at 800 °C and in the reactant flow with the steam-to-carbon (S/C) feed ratio of 1.0 indicated that the Ni/K2TixOy–Al2O3 catalysts were more active, thermally stable and resistant to deactivation than the non-promoted Ni/Al2O3. It is considered that the appropriate interaction strength between nickel and the modified support and proper K2TixOy phases with a surface monolayer coverage achieved at ca. 15 wt.% loading in the support play important roles in promoting the steam methane reforming activity as well as suppressing the sintering of the catalyst.