The invention is a family of hydrophobic, low viscosity, low vapor pressure physical solvents with molecular structures consisting of two or more alkyl-ester functional groups on a central hydrocarbon chain. These solvents have been shown to possess high carbon dioxide (CO2) solubility and absorption selectivity, which make them well suited for the removal of CO2 from hydrogen (H2) produced from synthesis gas. This technology is available for licensing and/or further collaborative research from the U.S. Department of Energy’s National Energy Technology Laboratory.
Future integrated gasification combined cycle (IGCC) power plants and steam methane reforming (SMR) chemical plants have the potential to reduce the cost of CO2 capture. These power and chemical plants generate high-pressure CO2 gas streams from the in-situ water gas shift reaction when producing H2 used to power the electrical turbines. A variety of methods have been proposed to capture CO2, including solvent, sorbent, and membrane technologies, with continuous solvent looping systems currently considered to be the most advanced. Precombustion capture of CO2 is typically accomplished using physical solvents.
State-of-the-art precombustion CO2 capture processes predominantly employ hydrophilic physical solvents. Current commercial physical solvents touted for IGCC CO2 capture were developed for removing acid gases from raw natural gas streams. Therefore, they were designed to remove significant amounts of water from the process gas. As such, the focus was on the purification of the process gas with less concern for generation of high-purity CO2 streams suitable for pipeline transmission and sequestration. While water removal is important for natural gas pipeline applications, it is not favorable for applications in which the fuel stream is directly combusted on-site, as would be encountered in IGCC systems.
Researchers at NETL have developed a family of hydrophobic, low viscosity, low vapor pressure physical solvents with molecular structures consisting of two or more alkyl-ester functional groups on a central hydrocarbon chain. These solvents have been shown to possess high CO2 solubilities at high CO2 partial pressures (such as ~ 25 bar) and high CO2/H2 absorption selectivity and are well suited for the removal of CO2 from H2 produced from synthesis gas. The NETL-developed solvents offer attractive properties for applications involving CO2 capture from high humidity H2 gas streams containing elevated partial pressures of CO2, particularly in IGCC processes. The rare combination of low toxicity, high CO2 capacity, high selectivity, and low water affinity of these solvents provide opportunities for more efficient, cost-effective and environmentally friendly CO2 mitigation.
Applications of Hydrophobic Alkyl-Ester Physical Solvents include:
U.S. Patent Pending (provisional patent application)
Title: Hydrophobic Alkyl-Ester Physical Solvents for CO2 Removal from H2 Produced from Synthesis Gas
Inventors: Wei Shi, Jeffrey T. Culp, Robert L. Thompson, Surya P. Tiwari, Kevin P. Resnik, Lei Hong, Jan Steckel, David Hopkinson, Nicholas Siefert
Ref No. 20N-25