Shin-Kun Ryi

Pd-Cu alloy membrane deposited on alumina modified porous nickel support (PNS) for hydrogen separation at high pressure

This study reports on the hydrogen permeation properties of Pd-Cu alloy membranes at high pressures. A 7 μm thick Pd-Cu alloy membrane was prepared on an alumina-modified porous nickel support (PNS) by our developed magnetron sputtering and Cu-reflow method at 700 °C for 2 hours. The membrane was mounted in a stainless steel permeation cell with a gold-plated stainless steel O-ring. Helium leak testing confirmed that the membrane and membrane module were free of defects. Permeation tests were then conducted using hydrogen at temperatures in the range from 678 to 816 K with a transmembrane pressure difference of 1–20 bars, which showed that the membrane had a hydrogen permeation flux of 1.06 mol m−2 s−1 at a temperature of 816 K and a pressure difference of 20 bars. EDX analysis was carried out after hydrogen permeation test at 816 K and showed that there was no intermetallic diffusion between the Pd-Cu layer and PNS because the alumina layer inhibited it effectively.

Methane steam reforming in a membrane reactor using high-permeable and low-selective Pd-Ru membrane

We performed a methane steam reforming (MSR) reaction through a membrane reactor packed with commercial Ni/Al2O3 catalyst and a tubular Pd-Ru membrane deposited on a YSZ modified porous stainless steel support under mild operating conditions: 773 K and a pressure difference range of 100-250 kPa. We prepared the Pd-Ru membrane with thickness of ~6 μm on a tubular stainless steel support (diameter 12.7mm, length 25 cm) using electroless plating, which was observed for the membrane performance using hydrogen and nitrogen. Gas permeation test carried out at 773 K and 31.4 kPa of pressure difference between retentate and permeate sides showed that the hydrogen permeation rate and nitrogen leakage were ~0.1050mol s−1 m−2 and ~0.0018 mol s−1 m−2, respectively. The MSR reaction was under the following conditions: temperature 773 K, pressure 100-250 kPa, gas hourly space velocity (GHSV) 837 h−1, and steam-to-carbon feed ratio (S/C) 3. The MSR reaction result showed that methane conversion was increased with increasing pressure difference and reached ~77.5% at 250 kPa. In this condition, the composition of carbon monoxide was ~2%, meaning that no two series of water gas shift reactors were needed in our membrane reactor system. Longterm stability test carried out for ~100 h showed that methane conversion and the hydrogen yield remained constant.

Ultra-thin Ni dense membrane prepared by polishing treatment of porous nickel support for high-temperature H2 separation

Ultra-thin nickel dense membranes (∼0.5 μm) were developed by polishing treatment of porous nickel supports. The polishing treatment involved the use of 400 grit sand paper, 1000 grit, and 1500 grit, which was able to remove the surface pores due to the ductility of the PNS. The hydrogen permeation test showed that 4.53×10−2 mol m−2 s−1 of hydrogen permeation flux through the membrane could be achieved at a temperature of 973K and a pressure difference of 136 kPa. The nitrogen leakage tests confirmed that there were no pinholes on the surface of the ultra-thin nickel dense membrane.