Pd and Pd-Cu membranes:: inhibition of H2 permeation by H2S
Pd and Pd-Cu membranes:: inhibition of H2 permeation by H2S
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DOI：
10.1016/j.memsci.2004.11.031
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发表时间：
2005-06-01
影响因子：
9.5
通讯作者：
Way, JD
中科院分区：
文献类型：
--
作者：
Kulprathipanja, A;Alptekin, GO;Way, JD
低浓度H2S通过阻断H-2解离位点，降低了化学镀Pd和Pd- cu合金膜中H-2的渗透。在高H2S浓度下，硫表面层甚至不允许H-2渗透到Pd-Cu表面。钯和铜的硫化形成微米大小的孔，导致膜失效。H2S浓度与暴露时间无关；对Pd-Cu来说，完全抑制H-2渗透的H2S浓度约为300 ppm。合金和100 ppm的Pd表面。在较低的H、S浓度下，获得稳态渗透。硫化氢暴露和H-2后处理由于应力松弛导致Cu向膜进料侧偏析。对于体积Cu浓度高于60% wt%的膜，相由体心立方（bcc）变为面心立方（fcc）， H-2渗透率降低。与热力学预测的结果一样，在523 K时，由于钯和铜的硫化程度更高，H，S暴露时形成的裂纹和孔隙比723 K时形成的裂纹和孔隙更大。H2O的存在还通过帮助H2S解离和阻断H-2解离位点来促进硫化。铸箔和轧制箔表面光滑，不容易被H2S重新排列。与粗糙的表面相比，光滑的表面具有更小的表面积和单位面积吸附更少的硫。(c) 2005 Elsevier B.V.版权所有
Low concentrations of H2S decreased H-2 permeation through electroless-plated Pd and Pd-Cu alloy membranes by blocking H-2 dissociation sites. At high H2S concentrations, a sulfur surface layer-did not allow H-2 to even penetrate to the Pd-Cu surface. Sulfidation of Pd and Cu formed micron size pores and caused the membrane to fail. Failure depended on H2S concentration, not time of exposure; the H2S concentration that completely inhibited H-2 permeation was approximately 300 ppm for Pd-Cu. alloys and 100 ppm for Pd surfaces. At lower H,S concentrations, steady state permeation was obtained. Hydrogen sulfide exposure and H-2 post-treatment caused Cu segregation to the membrane feed side due to stress relaxation. For membranes with bulk Cu concentration above 60 wt%, the phase changed from body-centered cube (bcc) to face-centered cube (fcc), and this decreased H-2 permeability. Larger cracks and pores formed during H,S exposure at 523 K than at 723 K due to a higher degree of Pd and Cu sulfidation, as predicted by thermodynamics. The presence of H2O also increased sulfidation by aiding H2S dissociation and blocking H-2 dissociation sites. Cast and rolled foils, which have smoother surfaces, were less prone to surface rearrangement by H2S. Smoother surfaces have less surface area and adsorb less sulfur per unit area compared to rougher surfaces. (c) 2005 Elsevier B.V. All rights reserved.