High-Temperature Membrane for Energy-Efficient Gas Separation | SRI International

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Mini pilot plant, showing SRI's membrane and associated instrumentation

High-Temp Membrane for Energy-Efficient Gas Separation

SRI’s hollow fiber membrane separates hydrogen from carbon dioxide at high temperatures and improves the economics of carbon capture from IGCC plants.

SRI’s hollow fiber membrane separates hydrogen from carbon dioxide at high temperatures and improves the economics of carbon capture from IGCC plants.

Integrated gasification combined-cycle (IGCC) technology has the potential to produce electricity from coal in a more cost-effective and environmentally friendly manner than processes based on coal combustion. IGCC uses a gasifier to produce a mixed-gas stream (commonly called “syngas”) that contains carbon monoxide, hydrogen, carbon dioxide, and other compounds. SRI has developed a membrane to separate carbon dioxide and hydrogen at high temperature so the carbon dioxide can be captured and the hydrogen can be converted into electricity or chemicals.

SRI’s innovation includes a process to spin hollow fibers from the temperature-resistant polymer polybenzimidazole (PBI). This membrane is also chemically robust and can operate in the presence of hydrogen sulfide. The fibers are packaged into membrane modules that can separate hydrogen and carbon dioxide at 250°C. Performing the separation at this high temperature keeps the carbon dioxide at the high pressure (40 bar) of the coal gasifier, thereby reducing the power required to compress the gas to a pipeline pressure of 150 bar. Hydrogen and steam permeate the membrane quickly at this temperature, keeping the module size small.

The steam also increases electrical output in the gas turbine, improving overall economics for electricity production. Initial results indicate that the cost of electricity for the PBI membrane-based capture system is significantly less than that for a Selexol™ (solvent)-based capture system. In 2016, SRI plans to begin testing a bench-scale unit using a slipstream at a field site.

Gasification technology can also be used to produce chemicals from coal or other hydrocarbons, including coke and biomass. SRI’s membrane can be used in other processes, such as chemical production, that require the separation of hydrogen and carbon dioxide.  

This material is based upon work supported by the Department of Energy under award numbers DE-FC26-07NT43090 and DE-FE0012965. This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.