Metallic Based Aqueous Amine Membranes for the Separation of Carbon Dioxide From Fossil Fuel Flue Gas

According to the US Department of Energy, there is scientific evidence that CO₂ emissions from fossil fuels have caused climate change and that a reduction of these emissions is essential for reducing the risk of future devastating effects. At present, the leading technology for the post combustion capture of CO₂ relies on the separation of CO₂ from the flue gas stream by employing chemical absorption with an aqueous monoethanolamine (MEA) solution.  The separation is followed by compression of the gas to a liquid or supercritical state for transportation, and ultimately long term storage in geological formations.  However, there is little experience with large scale amine separation systems especially in oxidizing environments typical of a fossil fuel flue gas stream.  Furthermore, there are concerns about the degradation rate and evaporative losses of the amine solution and the amount of energy required for regeneration.

We propose using metallic supported liquid amine membranes to overcome the shortcomings of the large energy intensive amine process.  Because the amine solution is immobilized in the pores of a thin nanoporous layer there is a lower vapor pressure thereby reducing the evaporation rate and the thin layer requires a small fraction of the amine compared to the absorption method.   The membrane can be operated at a constant temperature, lower than the absorption process regeneration temperature, which reduces the degradation rate of the amine.  We prepared a series of robust membranes based on a stainless steel support structure and a very thin nanoporous aluminum oxide layer that holds the aqueous amine solution.  We will present laboratory results showing flux data and selectivity data for a range of amines under varying temperatures.  We will also present stability data which demonstrates a strong promise for long-term application.