Methane steam reforming using Mn-promoted nickel/ceria-zirconia mixed oxide catalysts

Abstract

Methane team reforming (MSR) is a well-known process for converting natural gas into syngas, a mixture of H₂ and CO. Ni-based catalysts are typically employed in industry for this steam reforming reaction. However a major problem arisen is the rapid deactivation of catalyst due to coke deposition. CeO₂-ZrO₂ supports capable of oxidizing the deposited carbon have previously demonstrated improved stability, conversion, and hydrogen yield. Recently, manganese has been considered an interesting promoter affecting the performance and suppressing carbon deposition on nickel catalysts. Therefore, the role of manganese and nickel incorporated onto Ce₀.₇₅Zr₀.₂₅O₂ mixed oxide catalysts prepared via the co- and multi-step incipient wetness impregnation methods was investigated in terms of activity, stability, and inhibition of carbon deposition on methane steam reforming. The catalytic activity for methane steam reforming was studied at 600-800°C under atmospheric pressure using a stoichiometric steam to methane ratio of 4:1 for 5 hours. The results showed that the addition of Mn enhanced the water gas shift reaction as demonstrated high hydrogen yield. 15 Ni5Mn/CZO (S) exhibited the best activity and stability of MSR as a reducibility of less metal support interaction. Moreover, the multi-step incipient wetness impregnation method gave a better catalytic activity than those prepared via co-impregnation method under the same operating conditions.