Abstract
A supported Pd-Au (Au 7wt%) membrane was produced by electroless plating deposition. Permeation tests were performed with pure gas (H2, H2, N2, CO2, CH4) for long time operation. After around 400 h under testing, the composite Pd-Au membrane achieved steady state condition, with an H2/N2 ideal selectivity of around 500 at 420 °C and 50 kPa as transmembrane pressure, remaining stable up to 1100 h under operation. Afterwards, the membrane was allocated in a membrane reactor module for methane steam reforming reaction tests. As a preliminary application, at 420 °C, 300 kPa of reaction pressure, space velocity of 4100 h−1, 40% methane conversion and 35% hydrogen recovery were reached using a commercial Ni/Al2O3 catalyst. Unfortunately, a severe coke deposition affected irreversibly the composite membrane, determining the loss of the hydrogen permeation characteristics of the supported Pd-Au membrane.
Highlights
The current development in energy use is oriented towards reducing carbon consumption due to its environmental pollution
The objective of the present work is to investigate the long-term stability characteristics of hydrogen permeation of a composite membrane constituted of a Pd-Au (Au 7wt%) dense layer supported on a porous stainless steel (PSS) support, evaluating the H2 /N2, H2 /CO2, H2 /CH4 and H2 /He ideal selectivities
We investigated the performance of a supported Pd-Au membrane in terms of hydrogen permeance and ideal selectivity in pure gas permeation tests under long time continuous operation
Summary
The current development in energy use is oriented towards reducing carbon consumption due to its environmental pollution. Hydrogen as a clean and sustainable energy carrier has gained more attention during the past decades. When hydrogen reacts with oxygen in fuel cells and internal combustion engines, a large amount of energy is released explosively in heat engines and quietly in fuel, releasing water as the product. The present source of hydrogen comes mainly from synthesis gas, which is a mixture of H2 , CO and CO2 , and it is produced by breaking the strong C-H bonds (439 kJ/mol) of hydrocarbons in reforming reactions. Afterwards, hydrogen is purified and separated by different energy intensive steps. A membrane reactor (MR) technology can represent an energetically efficient option to the conventional processes, with the practical advantages of a smaller footprint and capital cost reduction
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