Preparation, Characterization, and Activity of Pd/PSS-Modified Membranes in the Low Temperature Dry Reforming of Methane with and without Addition of Extra Steam

The external surface of a commercial porous stainless steel (PSS) was modified by either oxidation in air at varying temperatures (600, 700, and 800 °C) or coating with different oxides (SiO(2), Al(2)O(3), and ZrO(2)). Among them, PSS-ZrO(2) appears as the most suitable carrier for the synthesis of the Pd membrane. A composite Pd membrane supported on the PSS-ZrO(2) substrate was prepared by the electroless plating deposition method. Supported Ru catalysts were first evaluated for the low-temperature methane dry reforming (DRM) reaction in a continuous flow reactor (CR). Ru/ZrO(2)-La(2)O(3) catalyst was found to be active and stable, so it was used in a membrane reactor (MR), which enhances the methane conversions above the equilibrium values. The influence of adding H(2)O to the feed of DRM was investigated over a Ru/ZrO(2)-La(2)O(3) catalyst in the MR. Activity results are compared with those measured in a CR. The addition of H(2)O into the feed favors other reactions such as Water-Gas Shift (RWGS) and Steam Reforming (SR), which occur together with DRM, resulting in a dramatic decrease of CO(2) conversion and CO production, but a marked increase of H(2) yield.