Preparation, characterization, and activity of pd/pss-modified membranes in the low temperature dry reforming of methane with and without addition of extra steam

Abstract

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 (SiO2, Al2 O3, and ZrO2). Among them, PSS-ZrO2 appears as the most suitable carrier for the synthesis of the Pd membrane. A composite Pd membrane supported on the PSS-ZrO2 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/ZrO2-La2 O3 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 H2 O to the feed of DRM was investigated over a Ru/ZrO2-La2 O3 catalyst in the MR. Activity results are compared with those measured in a CR. The addition of H2 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 CO2 conversion and CO production, but a marked increase of H2 yield.