Sealing perovskite membranes for long-term oxygen separation from air
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REVIEW
Sealing perovskite membranes for long‑term oxygen separation from air Yousef Alqaheem1 · Abdulaziz A. Alomair1 Received: 30 January 2020 / Accepted: 27 June 2020 © Institute of Chemistry, Slovak Academy of Sciences 2020
Abstract Oxygen is industrially produced by cryogenic distillation but the process is energy-intensive. Perovskite membranes can provide an economical solution for oxygen production because of low energy input. However, the technology is not commercialized due to one of the challenges which is sealing the membrane at high temperature. Unfortunately, there is no universal sealant that can be used for all perovskite membranes. Factors such as membrane material, geometry and operating conditions can critically affect the sealant selection. This paper overviews current sealing methods for perovskite membranes for long-term oxygen separation with various membrane geometries such as disk, tubular and hollow fiber. Keywords Perovskite membranes · Sealing · Oxygen flux · Gas-tight system
Introduction The demand for oxygen has increased recently due to the need for clean and efficient processes. Air contains 21 mol% of oxygen and it is typically used for fuel combustion. Nevertheless, due to the lower oxygen content, pollutants such as nitrogen oxides are formed. These oxides are known to cause risk to the respiratory system in the long run (Amster et al. 2014). They also contribute to the formation of fine particles and ground-level ozone (Wei et al. 2019). The use of enriched oxygen will not only cut nitrogen oxide emissions but will also reduce fuel consumption due to the higher flame temperature. For instance, in industrial furnaces, the use of enriched oxygen can lower fuel consumption by 60% with minimization of nitrogen oxides by 35% (Acton 2013; Baukal 2010). Enriched oxygen contains more than 21 mol% of oxygen (balance nitrogen) but if the oxygen stream is pure, then the burning process is called oxyfuel combustion. The technology is implemented in power plants not only to increase the combustion efficiency, but also to reduce the volume of the exhaust gas.
* Yousef Alqaheem [email protected] 1
Petroleum Research Center, Kuwait Institute for Scientific Research, Ahmadi, Kuwait
Oxygen is conventionally produced by cryogenic distillation by cooling down the air to an extreme temperature of – 192 °C in which the oxygen will be liquefied (Langlais et al. 2019). This technology produces high-quality oxygen (> 99.9 mol%) however, the process is energy-intensive and requires high capital and operating costs (Sadrzadeh and Mohammadi 2019). Ceramic membranes can provide an alternative route for oxygen separation with the ability to produce oxygen with 99.9 mol% in purity (Liang et al. 2010). These membranes are made from metal oxides with a perovskite structure containing oxygen vacancies that can be activated at a high temperature. Due to a large number of oxygen vacancies, the membranes are able to produce a high flux of oxygen (Leo et al. 2011). Industrially, a minimum flux of 1 ml c
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