Abstract

Generation of oxygen using pressure swing adsorption (PSA) has been commercialized for a few decades. However, the efficiency of the adsorption process in purifying O₂ has typically dropped with operating times. In this study, the reasons for the loss of adsorption capacity of zeolite samples collected from a commercial PSA-based O₂ generator were investigated. It was illustrated that the adsorption of H₂O molecules on a lithium-exchanged low silica X zeolite (Li zeolite) and the replacement of Li⁺ with Na⁺ in the zeolite structure were major causes for the loss of selective adsorption of the zeolite. While the H₂O molecules could be desorbed and the surface area of the adsorbent could be regained by vacuum heating at 200 °C and 90 kPa, the N₂/O₂ separation efficiency of the adsorbent could not be recovered. An elemental composition analysis showed that when an active Li zeolite was placed in a high salinity, wet air flow, there occurred vapor-phase ion exchange between Na⁺ and Li⁺ cations. The results from this study showed that airborne salinity in a working environment was detrimental to adsorption processes with Li zeolite as the adsorbent.

摘要

使用变压吸附 (PSA) 产生氧气已经商业化了几十年。_{然而，净化O 2}的吸附过程的效率通常随着运行时间而下降。在这项研究中，调查了从商用 PSA 基 O ₂发生器收集的沸石样品吸附能力损失的原因。结果表明，H _{2 O分子在锂交换低二氧化硅X沸石（Li沸石）上的吸附以及沸石结构中Li} ⁺被Na ⁺取代是沸石选择性吸附丧失的主要原因。而 H ₂在200℃和90kPa的真空加热条件下，O分子可以解吸，吸附剂的表面积可以恢复，吸附剂的N 2 _/ O ₂分离效率不能恢复。^{元素组成分析表明，当将活性锂沸石置于高盐度、潮湿的空气流中时，Na +}和 Li ⁺阳离子之间会发生气相离子交换。这项研究的结果表明，工作环境中的空气盐度对以锂沸石作为吸附剂的吸附过程是有害的。