Ni Thin Layer Catalysts for Making H2 "COx-Free" by Decomposition of Natural Gas in a Structured Multilayer Reactor

The decomposition of methane for making "COx-free" hydrogen on Ni based thin layer catalysts (Ni-TLCs) in a structured multilayer reactor (MLR) in the range 773-873K has been investigated. Ni-TLCs were prepared by a procedure involving the washcoating of a silica cloth with a colloidal silica solution and the subsequent impregnation of the SiO2/silica cloth support with the Ni precursor solution. Characterization of fresh and used catalyst samples by SEM, TEM and H-2-TPD techniques has allowed to depict surface and textural properties of the Ni-TLCs as well to probe the nature of the coke. The performance of the Ni-TLCs in the title reaction is controlled by the Ni loading, Ni particle size and reaction temperature. Filamentous and/or encapsulating carbon deposits have been detected. The steeper deactivation and the shorter catalyst lifetime at 873K are associated with the formation of encapsulating coke. Direct insights on the structure sensitive nature of the title reaction have been achieved.