Long-Term Stability of Thin-Film Pd-Based Supported Membranes

Membrane reactors have demonstrated a large potential for the production of hydrogen via reforming of different feedstocks in comparison with other reactor types. However, the long-term performance and stability of the applied membranes are extremely important for the possible industrial exploitation of these reactors. This study investigates the long-term stability of thin-film Pd-Ag membranes supported on porous Al2O3 supports. The stability of five similarly prepared membranes have been investigated for 2650 h, up to 600 °C and in fluidized bed conditions. Results show the importance and the contribution of the sealing of the membranes at temperatures up to 500 °C. At higher temperatures the membranes surface deformation results in pinhole formation and a consequent decrease in selectivity. Stable operation of the membranes in a fluidized bed is observed up to 450 °C, however, at higher temperatures the scouring action of the particles under fluidization causes significant deformation of the palladium surface resulting in a decreased selectivity.The presented work is funded within BIONICO. This project has received funding from the Fuel Cells and Hydrogen 2 Joint Undertaking under grant agreement No 671459. This Joint Undertaking receives support from the European Union’s Horizon 2020 Research and Innovation Programme, Hydrogen Europe and N.ERGHY

Pd-Based Membranes for High Temperature Applications: Current Status

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Fluidized Bed Membrane Reactors for Ultra Pure H2 Production - A Step forward towards Commercialization

In this research the performance of a fluidized bed membrane reactor for high temperature water gas shift and its long term stability was investigated to provide a proof-of-concept of the new system at lab scale. A demonstration unit with a capacity of 1 Nm3/h of ultra-pure H2 was designed, built and operated over 900 h of continuous work. Firstly, the performance of the membranes were investigated at different inlet gas compositions and at different temperatures and H2 partial pressure differences. The membranes showed very high H2 fluxes (3.89E 6 mol m 2 Pa 1 s 1 at 400 C and 1 atm pressure difference) with a H2/N2 ideal perm-selectivity (up to 21,000 when integrating five membranes in the module) beyond the DOE 2015 targets. Monitoring the performance of the membranes and the reactor confirmed a very stable performance of the unit for continuous high temperature water gas shift under bubbling fluidization conditions. Several experiments were carried out at different temperatures, pressures and various inlet compositions to determine the optimum operating window for the reactor. The obtained results showed high hydrogen recovery factors, and very low CO concentrations at the permeate side (in average <10 ppm), so that the produced hydrogen can be directly fed to a low temperature PEM fuel cell

Morphology and N2 Permeance of Sputtered Pd-Ag Ultra-Thin Film Membranes

The influence of the temperature during the growth of Pd-Ag films by PVD magnetron sputtering onto polished silicon wafers was studied in order to avoid the effect of the support roughness on the layer growth. The surfaces of the Pd-Ag membrane films were analyzed by atomic force microscopy (AFM), and the results indicate an increase of the grain size from 120 to 250–270 nm and film surface roughness from 4–5 to 10–12 nm when increasing the temperature from around 360–510 K. After selecting the conditions for obtaining the smallest grain size onto silicon wafer, thin Pd-Ag (0.5–2-µm thick) films were deposited onto different types of porous supports to study the influence of the porous support, layer thickness and target power on the selective layer microstructure and membrane properties. The Pd-Ag layers deposited onto ZrO2 3-nm top layer supports (smallest pore size among all tested) present high N2 permeance in the order of 10−6 mol•m−2•s−1•Pa−1 at room temperature.The presented work is funded within the FluidCELL project (Advanced m-CHP fuel CELL system based on a novel bio-ethanol Fluidized bed membrane reformer) as part of the European Union’s Seventh Framework Programme (FP7/2007-2013) for the Fuel Cells and Hydrogen Joint Technology (FCH JU) Initiative under Grant Agreement No. 621196. Note: “The present publication reflects only the authors’ views and the FCH JU and the Union are not liable for any use that may be made of the information contained therein”. This work is also partly funded by the MEMPORE project (Development of novel nanostructured membranes for micro-cogeneration (m-CHP)) (PI_2014_1_25) from the Basque Department of Education, Language policy and Culture. The authors would like to thank Rauschert Kloster Veilsdorf for providing the ceramic tubular supports

Fluidized bed membrane reactors for ultra pure H\u3csub\u3e2\u3c/sub\u3e production - A step forward towards commercialization

\u3cp\u3eIn this research the performance of a fluidized bed membrane reactor for high temperature water gas shift and its long term stability was investigated to provide a proof-of-concept of the new system at lab scale. A demonstration unit with a capacity of 1 Nm\u3csup\u3e3\u3c/sup\u3e/h of ultra-pure H\u3csub\u3e2\u3c/sub\u3e was designed, built and operated over 900 h of continuous work. Firstly, the performance of the membranes were investigated at different inlet gas compositions and at different temperatures and H\u3csub\u3e2\u3c/sub\u3e partial pressure differences. The membranes showed very high H\u3csub\u3e2\u3c/sub\u3e fluxes (3.89 × 10\u3csup\u3e-6\u3c/sup\u3e mol·m\u3csup\u3e-2\u3c/sup\u3e· Pa\u3csup\u3e-1\u3c/sup\u3e·s\u3csup\u3e-1\u3c/sup\u3e at 400 °C and 1 atm pressure difference) with a H\u3csub\u3e2\u3c/sub\u3e/N\u3csub\u3e2\u3c/sub\u3e ideal perm-selectivity (up to 21,000 when integrating five membranes in the module) beyond the DOE 2015 targets. Monitoring the performance of the membranes and the reactor confirmed a very stable performance of the unit for continuous high temperature water gas shift under bubbling fluidization conditions. Several experiments were carried out at different temperatures, pressures and various inlet compositions to determine the optimum operating window for the reactor. The obtained results showed high hydrogen recovery factors, and very low CO concentrations at the permeate side (in average \u3c/p\u3