Helium separation using inorganic membranes
More energy-efficient extraction of helium using new membranes
Helium (He) is used as a protective gas in various industrial applications. For example, helium is used in the production of silicon wafers for microelectronics, photovoltaics and microsystems technology. Many analytical devices such as gas chromatographs also require helium. Helium is not a rare element on earth, but it only ever occurs in low concentrations. It is currently extracted exclusively from natural gas. When natural gas is extracted, wells usually contain He concentrations of around 0.1 – 0.3 per cent by volume. Only a few sources worldwide have higher concentrations. There are no other currently usable helium sources.
Helium is extracted by liquefying the natural gas. With the increasing production of liquefied natural gas, the number of usable helium sources has risen. Nevertheless, a large number of natural gas sources with low helium concentrations are not utilised due to the high energy requirement for liquefaction. Membranes could separate and enrich the helium from the natural gas and other gas mixtures with considerably less energy input. There are a few polymer membranes that can be used for this purpose. However, the selectivity and mass transport of the membranes are limited and the mechanical stability against high pressure and the chemical stability against hydrocarbons or sulphur compounds are low.
The Helios project therefore aims to synthesise and investigate inorganic membranes (made of zeolites and carbon). On the one hand, these should be chemically and thermally stable and, on the other hand, have a significantly higher selectivity. In addition to helium extraction, the new membrane types will also open up the field of application of helium recovery from analytical devices. This is being investigated in the project using gas chromatography as an example.
In the project, the procedure for membrane production is carried out along the value chain, starting with carrier production, carrier testing, membrane development and their application-related characterisation options. The project enables future-orientated separation processes using a ceramic membrane with high He permeability and selectivity. By using such a membrane, cost-intensive separation operations, such as cryogenic gas separation, could be replaced by energy-efficient and resource-saving membrane processes.
