Ceramics used as intermetallic diffusion barriers in Pd-based composite membranes sputtered on porous nickel supports

Recent Advances in Pd-Based Membranes for Membrane Reactors

“…Some research groups prepared in-house metallic porous supports. A PSS tubular support was prepared by Straczewski using powder from GKN Sinter Metals [ 130 ]. On the other hand, nickel porous support were prepared by sintering commercial nickel powder supplied by Vale Inco Pacific Ltd., Hong Kong (SAR), China [ 106 , 131 ].…”

“…Ceramics used as inter-diffusion barrier need to have as similar thermal expansion coefficient as the selective metallic layer and support. The most common barrier material, alumina [ 123 , 138 , 139 , 140 ], has a low thermal expansion coefficient compared with ZrO 2 [ 108 , 120 , 141 , 142 , 143 , 144 ] or YSZ (yttria stabilized zirconia) [ 120 , 125 , 128 , 130 , 145 ], which both have larger thermal expansion coefficients and closer to Pd and its alloys (see Table 4 ). Other ceramic layers used as barrier are TiO 2 [ 120 , 130 ] or CeO 2 [ 106 , 146 ] which both possess a large thermal expansion coefficient and close to the thermal expansion coefficient of Pd.…”

A tailor-made porous stainless steel support for a dense hydrogen separation membrane

“…The support's surface morphologies such as roughness, pore size, and degree of open-pores significantly affect membrane performance because they are directly related to membrane thickness. Therefore, proper surface modification processes to reduce roughness and largest pore size and also to keep the open-pores are needed, including mechanical and/ or chemical polishing, etching, coating, and filling [4,13]. In the case of the plate-type support, it is easy to modify its surface morphologies with polishing and/or filling methods.…”

“…In general, the thinner the Pd-based layer is coated on the metal support, the more important the interdiffusion barrier to prevent intermetallic diffusion between the metal substrate and Pd-based membrane becomes. The barrier layer can be formed by alumina coating via solegel technique, zirconia sputtering [13] or controlled surface oxidization [15]. As a result of the effort to overcome these issues, the disc-shaped PdeAu membrane was prepared by the following methods: (1) the surface modification of the porous metal support by the polishing and filling methods [13], (2) zirconia sputtering as the interdiffusion barrier [13], (3) PdeAu deposition and then (4) post-polishing for Pd densification [14].…”

“…The barrier layer can be formed by alumina coating via solegel technique, zirconia sputtering [13] or controlled surface oxidization [15]. As a result of the effort to overcome these issues, the disc-shaped PdeAu membrane was prepared by the following methods: (1) the surface modification of the porous metal support by the polishing and filling methods [13], (2) zirconia sputtering as the interdiffusion barrier [13], (3) PdeAu deposition and then (4) post-polishing for Pd densification [14]. A combined test of the water-gas shift reactor and the membrane reactor for pre-CCS in a coal gasifier was carried out by using the disc-shaped PdeAu membranes [16].…”