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

Cecilia Mateos-Pedrero,Miguel A Soria,Inmaculada Rodríguez-Ramos,Antonio Guerrero-Ruíz

doi:10.3390/membranes11070518

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, Al2O3, 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-La2O3 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 H2O to the feed of DRM was investigated over a Ru/ZrO2-La2O3 catalyst in the MR. Activity results are compared with those measured in a CR. The addition of H2O 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.

Highlights

Pd-based membranes have received much attention owing to their high permeability and selectivity to hydrogen, which is suitable for various applications involving H2 separation and purification process [1,2]
Supported Ru catalysts were first evaluated for the low-temperature methane dry reforming (DRM) reaction in a continuous flow reactor (CR)
EenlesregwyhaenrdeX[2P4S]a. tTohmeicTrPaRtiops)rofofriltehoefsuthpepofrretesdhRsaumcaptalely(satss.ingle peak located at 150–161 °C is observed, Table 5) and XPS (BE of Ru3d5/2 = 280.4–280.9 eV) of the catalysts after reduction trCeaattamlysetnt reduction (iTnTaPbhRlyed(◦5rC)o.)gReun(/μZ(mN5rOo0ald02/sg-S°caCitO) f2oarnD2d(h%R))uc/oZnrOfir2d-mL(namt2hO)e3 pre*sBen

Summary

Introduction

Pd-based membranes have received much attention owing to their high permeability and selectivity to hydrogen, which is suitable for various applications involving H2 separation and purification process [1,2]. The support should have a small external pore size and a smooth surface to form a thin Pd membrane without defects. In this way, PSS are promising supports because of their high-pressure resistance, good mechanical strength, high thermal stability, etc. A commercial PSS carrier has non-uniform and too large external pore size, which makes more difficult the deposition of a thin dense Pd layer onto this support. Direct deposition of Pd layer onto PSS surface would give rise to an intermetallic diffusion between the metallic elements of PSS and Pd, decreasing the stability of the membrane

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Results

Conclusion