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Hydrophobic Carbon Capture Solvent

USPN 10,589,228

Opportunity

Research is active on the design and synthesis of a new carbon dioxide (CO2) capture solvent based on PEG-Siloxane. Unlike conventional gas-removal solvents, the NETL’s new solvent technology is hydrophobic and has a low vapor pressure. A hydrophobic solvent with low vapor pressure is highly advantageous because it can reduce the cost and energy-consumption associated with CO2 capture by simplifying solvent regeneration and negating the need to remove water from fuel gas. For example, this solvent operates above room temperature and can be regenerated using low-grade and waste heat, whereas commercially available solvents operate below room temperature and can’t be regenerated using low-grade or waste heat This technology is available for licensing and/or further collaborative research from the U.S. Department of Energy’s National Energy Technology Laboratory.

Overview

Unlike pre-combustion CO2 capture technologies currently employed at integrated gasification combined cycle (IGCC) systems, NETL’s PEG-Siloxane-based solvent is hydrophobic and has a low vapor pressure. Traditional solvents must operate at below room temperature, which requires the use of a chiller, and rely on a pressure-swing process to be regenerated. Both of these processes consume electricity, whereas the NETL patented solvent can operate at above room temperature and can be regenerated using waste/low-grade heat. This can result in a savings of approximately 50 MW at a 500 MW IGCC-CCS power plant.

Traditional carbon capture solvents may also suffer from foaming, which can significantly reduce the mass transfer of CO2 into the solvent because foaming requires that the absorber be operated at lower gas flow velocities. The novel NETL solvent reduces the tendency to foam under these conditions, which may help to keep capital costs for the absorber to a minimum.

Significance
  • Increases the output electricity by roughly 10% at an IGCC-CCS power plant
  • Potentially lowers the capital cost of capturing CO2 in an IGCC-CCS power plant
  • Offers a hydrophobic alternative to water-miscible solvents
  • Absorbs as much CO2 and as little water and hydrogen (H2) as possible at temperatures above 40 °C
  • Shows higher CO2/H2 selectivity at working conditions than widely used solvents
  • Maintains very low viscosity at working temperatures
  • Displays low volatility and high thermal stability
  • Exhibits reduced foaming tendencies when exposed to flowing gas
Applications

  • Pre-combustion CO2 separation and capture at IGCC-CCS

  • Generation of H2 from reformed natural gas or from syngas

  • Adjustment of CO/H2 ratio for Coal and Biomass to Liquids

  • Removal CO2 from syngas for Coal and Biomass to Ammonia/Fertilizer

  • Natural gas sweetening

  • Storage of light gases (carbon dioxide, methane, hydrogen, hydrogen sulfide)

Related Patents

U.S. Patent No: 10,589,228
Issued: 03/17/2020
Title: Di-Substituted Siloxane Solvents for Gas Capture
Inventors: David P. Hopkinson, Nicholas Siefert, Robert L. Thompson, Megan Macala, Lei Hong
NETL Reference No: 17N-14
 

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