Experimental investigation of a microchannel membrane configuration with a 1.4 μm Pd/Ag23 wt.% membrane—Effects of flow and pressure

A microchannel membrane configuration was tested by applying a thin self-supported Pd/Ag23 wt.% membrane (∼1.4 μm) on top of six parallel channels with dimensions 1 mm × 1 mm × 13 mm. The influence of feed flow rate and pressure was investigated and analyzed with respect to effects arising when hydrogen permeates from mixtures. A permeance of 1.7 × 10−2 mol m−2 s−1 Pa−0.5 was calculated from measurements in pure hydrogen at 573 K. The membrane was found to withstand differential pressures up to 470 kPa, without reaching the burst pressure. The high pressures employed conveniently allowed hydrogen separation from mixtures without the use of a sweep gas. Increasing the total feed flow rate resulted in increased hydrogen flux but decreased recovery. A simple simulation showed that only the first part of the membrane was utilized for lower total feed flow rates and higher total absolute feed pressures. During the ∼7 days of testing and pressure cycling in H2/N2 feed mixtures a small nitrogen leakage evolved, resulting in the H2/N2 separation factor to decrease from ∼5700 to ∼390 at ∼300 kPa differential pressure. The design represents a first step to a compact and efficient microchannel membrane reactor system for production and separation of hydrogen.