Effect of calcination atmosphere on microstructure and H2/CO2 separation of palladium-doped silica membranes

• Published in: Separation and purification technology Vol. 210; no. C; pp. 659 - 669
• Main Authors: Yang, Jing, Fan, Wangqing, Bell, Carl-Martin
• Format: Journal Article
• Language: English
• Published: United Kingdom Elsevier B.V 01.02.2019; Elsevier
• Subjects: Apparent permeation activation energy; Calcination atmosphere; H2/CO2 separation; Hydrothermal stability; Palladium-doped silica membrane; Apparent permeation activation energy; Hydrothermal stability; Palladium-doped silica membrane; H2/CO2 separation; Calcination atmosphere
• ISSN: 1383-5866; 1873-3794
• DOI: 10.1016/j.seppur.2018.08.041

[Display omitted] •The effect of calcination atmosphere on the microstructure of Pd/SiO2 membrane.•The effect of calcination atmosphere on the Ea value of H2 through Pd/SiO2 membrane.•The effect of calcination atmosphere on the H2/CO2 separation of Pd/SiO2 membrane.•Hydrothermal stability of Pd/SiO2 membrane. Palladium-doped silica materials with SiCH3 groups were fabricated by sol-gel method under various calcination atmospheres and membranes were made thereof by coating process. The results showed that air atmosphere can lead to the partial oxidation of metallic Pd0 to PdO while N2 and H2 atmospheres can effectively prevent metallic Pd0 from being oxidized. H2 atmosphere is proved to be a more prominent way to slow down the decomposition of organic SiCH3 group than N2 and air atmospheres. The surface area, micropore volume and porosity of palladium-doped silica membrane material calcined in H2 atmosphere are much higher than those calcined in N2 atmosphere. Compared with N2 atmosphere, the palladium-doped silica membranes calcined in H2 atmosphere showed higher H2 permeability and H2/CO2 selectivity before and after the steam exposure. The apparent activation energy of H2 permeation through the palladium-doped silica membrane calcined under H2 atmosphere (2.51 ± 0.05 kJ/mol) was slightly lower than that calcined under N2 atmosphere (2.84 ± 0.04 kJ/mol). Calcination atmosphere plays some role in membrane performance, which has greater influence on the permeance than on the gas permselectivity. Calcination under H2 atmosphere is well conducive to improve the gas permeance and H2 permselectivity of palladium-doped silica membrane.