Research is currently active on the patented technology "Process for CO2 Capture Using Zeolites from High Pressure and Moderate Temperature Gas Streams." The technology is available for licensing and/or further collaborative research from the U.S. Department of Energy’s National Energy Technology Laboratory.
This invention discloses a method for separating CO2 from a high-pressure and moderate- temperature gas stream composed of CO2 and other gaseous constituents using a zeolite sorbent in a temperature-swing adsorption process, which produces a CO2 stream at a high CO2 pressure contributing to low compression costs for CO2 sequestration. The method also uses CO2 desorption in a CO2 atmosphere and effectively integrates heat transfer to optimize overall efficiency. Current commercial processes for CO2 removal from high-pressure gas streams require gas cooling to ambient temperatures contributing to lower thermal efficiencies of the process. The overall efficiency of the CO2 removal process in the invention disclosure is higher than that of the com-mercial processes since the CO2 removal process takes place at moderate temperatures and CO2 can be recovered at high pressure. Presence of moisture in the gas stream does not affect the CO2 sorption/desorption process of the zeolites at the reaction conditions used in the process.
The emission of CO2 from power plants has been identified as a potential factor in long-term environmental problems. As a result, the separation of CO2 from gaseous streams by using adsorption of gases and vapors by micro-porous solids has attracted industry attention due to its importance in the fields of gas separation and gas purification. Therefore, technologies based on CO2 adsorption/desorption that use natural and synthetic zeolites are among the most effective methods.
Researchers have generally used two methods for CO2 adsorption/desorption that apply zeolite adsorbents for CO2 separation: temperature-swing adsorp-tion and pressure-swing adsorption. However, at lower pressures, the CO2 adsorption capacity of zeolites generally diminish rapidly as the tempera-ture of the gas being separated increases. In addition, moisture sorption contributes to decreasing CO2 capture capacities during multiple cycles.
Therefore, researchers needed a method to address these issues if zeolites are to be used in the CO2 capture process. This invention does just that by providing a method of CO2 separation by using zeolite adsorbents in a manner that preserves adsorption capacities at higher temperatures, recovering CO2 at high pressure and addressing the moisture issue.
U.S. Patent No: 8,128,735
Title: Process for CO2 Capture Using Zeolites from High Pressure and Moderate Temperature Gas Streams
Inventors: Ranjani Siriwardane, Robert W. Stevens
NETL Reference No: 08N-16
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