经济学人下载:制造氧气(1)

Making oxygen 

制造氧气

Magnetic moment 

磁矩

A new approach may make oxygen-manufacturing much cheaper 

一种新方法可能会使制造氧气成本更低

Oxygen is vital. Literally so for breathing, and thus for many hospital patients. And metaphorically for industries ranging from steelmaking to pharmaceuticals, which use it in their processes. The world market for the gas is therefore large. Various estimates put it as having been between about $28bn and $49bn in 2019. 

氧气至关重要，最直接的就是对呼吸至关重要，所以对医院的病人也至关重要。就像，从钢铁业到制药业，这些行业在其生产过程中都要使用氧气。因此氧气的世界市场很大。各种估计认为，2019年这一数字在280亿至490亿美元之间。

It could, though, be larger. In a set of reactions that also involve oxygen and steam, fossil fuels such as coal and natural gas can be turned into hydrogen, a source of energy, and carbon dioxide, which can be separated and sequestered underground. That might allow their continued employment in a world of restricted greenhouse-gas emissions. It would, however, require a cheap and abundant supply of oxygen. Which is why America's Department of Energy is sponsoring a project intended to pull oxygen from the atmosphere with magnets. 

不过，它可以更大。在一系列也涉及氧气和蒸汽的反应中，煤炭和天然气等化石燃料可以转化为氢(一种能源)和二氧化碳(可以分离并封存在地下)。这可能会让它们在一个温室气体排放受限的世界里继续就业。不过，它需要廉价而充足的氧气供应，这就是为什么美国能源部赞助了一个旨在用磁铁从大气中提取氧气的项目。

Dry air is a mixture of 21% oxygen, 78% nitrogen and 1% argon, with a few other trace gases such as carbon dioxide. At the moment, most of the world's pure oxygen is made by the liquefaction and subsequent distillation of air, to separate it into its components. This is done in large factories. The other source of oxygen, somewhat less pure, is small, mobile plants called oxygen concentrators. These either absorb the nitrogen into a porous substance called a zeolite, leaving behind a gas that is 90% oxygen, or force air through membranes more permeable to one gas than the other, yielding a somewhat less rich mixture. The alternative of magnetic separation is the brainchild of John Vetrovec, boss of Aqwest, a technology firm in Larkspur, Colorado. 

干燥的空气是21%的氧气、78%的氮气和1%的氩气的混合物，还有一些其他的微量气体，如二氧化碳。目前，世界上大部分的纯氧都是通过空气的液化和之后的蒸馏得到的，并将其分解成各种成分。这一过程是在大工厂里完成的。另一种纯度稍低的氧气来源于一种小型的、可移动的氧气浓缩器。它们要么将氮气吸收成一种叫做沸石的多孔物质，留下一种含90%氧气的气体，要么迫使空气穿过一种一种气体比另一种气体更容易渗透的薄膜，从而产生一种含量稍低的混合物。另一种磁力分离方法是由科罗拉多州拉克斯波市的一家技术公司Aqwest的老板约翰·维特威克想出来的。

Though oxygen cannot be magnetised permanently in the way that elements like iron can, it is attracted by magnetic fields. As a consequence, when air is pumped through such a field its oxygen gets concentrated in those places where the field is strongest. This concentration-enhancement is small. But if the oxygen-enriched part of the air stream could be separated from the oxygen-impoverished part, and then treated in the same way over and over again, it could be enriched to the point where it was pure enough to be useful. Dr Vetrovec thinks he knows how to do this. 

氧气虽然不能像铁那样被永久磁化，但它还是会被磁场吸引。结果就是，当空气被吸过这样一个场时，当中的氧气就会集中在这个场最强的地方。这种浓度增强作用很小。但是，如果能将气流中富氧部分与贫氧部分分离开来，然后以同样的方式反复处理，氧气就可以浓缩到足够纯的程度，从而发挥作用。维特威克博士认为自己知道如何做到这一点。