Gradient Amine Sorbents for Low Vacuum Swing CO₂ Capture at Ambient Temperature

Technical Report · Mon Jul 31 00:00:00 EDT 2023

DOI:https://doi.org/10.2172/1992922· OSTI ID:1992922

Chuang, Steven  ^[1]

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1. Univ. of Akron, OH (United States)

The growing concerns over CO₂ emissions have led to the development of various methods for CO₂ capture. CO₂ capture by amine-based sorbents has been achieved by temperature (thermal) swing adsorption (TSA) process, pressure swing adsorption (PSA) process, and temperature pressure or vacuuming swing adsorption (TPSA or TVSA) process for CO₂ capture. Amine sorbents for energy-efficient TSA, PSA, VSA, TPSA or TVSA CO₂ capture should possess a capability which allow adsorbed CO₂ to desorb and amine sorbent to be regenerated at low temperatures or low vacuums. Development of such amine sorbents would significantly decrease energy consumption and sorbent degradation during the regeneration step. The objective of this project is to develop a low vacuum swing adsorption (VSA) process for the capture of CO₂ from air. The focus is on the development of amine sorbent which allows CO₂ to adsorb in the form of weakly adsorbed CO₂. The weakly adsorbed CO₂ species can be collected from the sorbent by applying a low vacuum at ambient temperature. Specifically, no heating (i.e., thermal energy) is needed for regeneration of amine sorbents. This novel sorbent allows VSA to be operated at ambient temperature without a significant energy demand. This process eliminates the energy-intensive heating and cooling process in temperature swing adsorption (TSA) process. Ambient temperature operation could prolong the lifetime of sorbent and minimize the maintenance cost. Extensive sorbent studies with in-situ infrared spectroscopy have revealed the modifications of conventional amine sorbents with additives can increase the fraction of weakly adsorbed CO₂. The amine sorbents with loaded CO₂ can be regenerated in part by the following approaches: (i) mild heating to temperatures below 70 °C, (ii) flowing purging gas over modified amine sorbents at temperatures below 40 °C, (iii) vacuuming at pressure below 0.2 atm and temperatures below 40 °C. The performance of these modified amine sorbents has been tested in a 60 grams VSA unit at ambient temperatures. The results show that weakly adsorbed CO₂ which can be desorbed from modified amine sorbents with purging gas at 100 cc/min can also be evacuated at a vacuum of 1 psia at room temperature. A preliminary techno- economic analysis indicates the major cost of the VSA process with modified amine sorbents stems from the operation of vacuum pumps. Thus, developing an excellent sealing with minimum leakage for the VSA unit is the most critical task for further the development of this VSA technology.

• Research Organization: Univ. of Akron, OH (United States); Aspen Aerogels, Inc., Northborough, MA (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: FE0031958
• OSTI ID: 1992922
• Report Number(s): DOE-Akron-DE-FE0031958
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
54 ENVIRONMENTAL SCIENCES
Carbon Capture
Direct Air Capture
Modified Amine Sorbent