Recent Advances in Pd-Based Membranes for Membrane Reactors

Palladium-based membranes for hydrogen separation have been studied by several research groups during the last 40 years. Much effort has been dedicated to improving the hydrogen flux of these membranes employing different alloys, supports, deposition/production techniques, etc. High flux and cheap membranes, yet stable at different operating conditions are required for their exploitation at industrial scale. The integration of membranes in multifunctional reactors (membrane reactors) poses additional demands on the membranes as interactions at different levels between the catalyst and the membrane surface can occur. Particularly, when employing the membranes in fluidized bed reactors, the selective layer should be resistant to or protected against erosion. In this review we will also describe a novel kind of membranes, the pore-filled type membranes prepared by Pacheco Tanaka and coworkers that represent a possible solution to integrate thin selective membranes into membrane reactors while protecting the selective layer. This work is focused on recent advances on metallic supports, materials used as an intermetallic diffusion layer when metallic supports are used and the most recent advances on Pd-based composite membranes. Particular attention is paid to improvements on sulfur resistance of Pd based membranes, resistance to hydrogen embrittlement and stability at high temperature.The presented work is funded within Reforcell (grant agreement No. 278997) and FERRET (grant agreement No. 621181) projects as part of European Union's Seventh Framework Programme (FP7/2007-2013) for the Fuel Cells and Hydrogen Joint Technology Initiative

Membrane reactors for autothermal reforming of methane, methanol, and ethanol

This chapter discusses the application of membrane reactors for hydrogen production through autothermal reforming (ATR) reactions, with particular attention to the ATR of methane as fossil fuel and methanol and ethanol as biofuels. First the concept of ATR is explained, the catalysts used for such reactions are reported, and the traditional reactors are discussed. Afterwards, the membrane reactor concepts are discussed, and two possible configurations, namely the fluidized bed and the packed bed configuration, are discussed and compared. Modeling aspects of both reactors are introduced. Finally, the recent advances in membrane reactors for these reactions and future trends are discussed in the chapter

N2, He and CO2 diffusion mechanism through nanoporous YSZ/γ-Al2O3 layers and their use in a pore-filled membrane for hydrogen membrane reactors

Nanoporous ceramic supports for pore filled membranes were prepared on ceramic supports (α-Al2O3) with pore size of 100 nm by adding additional layers with different proportions of YSZ/γ-Al2O3 (ranging from 50% to 90% of YSZ) by dip-coating and the effect of different parameters in the preparation method have been investigated. The diffusion mechanisms of N2, He and CO2 through the supported nanoporous layers have been studied in detail with permeation measurements at a temperature range of 50–400 °C and pressure difference of 30–100 kPa. It was observed that as the amount of γ-Al2O3 in the nanoporous layers increases, the adsorption of CO2 is favored at low temperatures and pressures. Finally, a pore-filled Pd/YSZ/γ-Al2O3 (60 wt%YSZ-40 wt. γ-Al2O3) membrane was successfully prepared and its permeation performance was tested over 900 h at 500 and 550 C, showing relatively low ideal H2/N2 perm-selectivity of about 50 due to low hydrogen flu