The role of promoters in enhancing hydrogen production during catalytic decomposition of methane

Catalytic methane decomposition is a promising process for co-production of CO_x free hydrogen and carbon nanomaterials. In this work, iron-based catalysts, supported on ZSM5, were studied as an active catalyst for methane decomposition and nickel and cobalt were used to boost the methane conversion and catalyst stability. The prepared catalysts were tested at 700 °C with the 9:1 CH₄ to Ar feed ratio under atmospheric pressure in a fixed bed tubular reactor. The diffraction peaks showed the formation of corresponding metal oxides and their combination species. The activity profiles implied that promoted iron-based catalyst (NiFe/ZSM5) outperformed the rest of the catalysts with an initial activity of 81.51 % that remained 75 % at the end of 170 min time-on-stream. The unpromoted (Fe/ZSM5) suffered deactivation over time and hence NiFe/ZSM5 turned out to be the active and stable catalyst among the tested catalysts. The high-resolution transition electron microscopy (HRTEM) images of the best catalyst indicated the growth of multiwalled carbon nanotubes which followed tip-base-growth mechanisms.