Carbon Capture - Lab-Scale

To help the U.S. meet its new carbon capture goals, ISTC is working in collaboration with the Illinois State Geological Survey (ISGS) and the Applied Research Institute on the campus of the University of Illinois at Urbana-Champaign and external partner Trimeric Corporation of Buda, Texas, to develop an innovative, low-cost approach for CO2 capture from burning coal during electrical generation. The objectives of the research are to:

  • demonstrate a novel biphasic CO2 absorption process (BiCAP); and
  • generate engineering and scale-up data for next-stage scale up.

New Technology vs. Conventional Carbon Capture

The conventional CO2 absorption process (e.g., Monoethanolamine [MEA]; Figure 1) start with carbon dioxide-rich flue gas entering the absorber where the CO2 is absorbed and mixed with a solvent (in this case MEA); the clean gas leaves the top of the absorber. Then the CO2 rich solvent passes through a heat exchanger and a stripper where the solvent is stripped of the CO2 and returned to the absorber. The concentrated CO2 is then pressurized. While conventional carbon capture methods are effective in removing CO2, they are very energy intensive and nearly double the cost generating energy.

The introduction of a biphase CO2 extraction method after the absorber (Figure 2) helps increase the stripping capacity due to the increased concentration of CO2 in the second solvent phase. In addition, there is less energy and compression work required to compress the CO2. However, the equipment needed is still the same size as the conventional carbon capture technology making this method only slightly less cost intensive.

ISTC and its partners propose an advanced biphasic CO2 adsorption process, dubbed BiCAP (Figure 3), which has multi-liquid-liquid phase separation (LLPS) allowing low CO2 loading throughout absorption (Figure 4), resulting in faster kinetics. In addition, BiCAP solvents have larger solvent capacities both for absorption and stripping which in turn further reduces the heat needed, compression work requirements, and CO2 stripper size.

  Flow diagram of the conventional carbon dioxide absorption process - see first paragraph in New Technology section for description.
Figure 1: Conventional CO2 Absorption Process.

  Flow diagram of Biphasic carbon dioxide absorption process - see the first and second paragraph in New Technology section for description.
Figure 2: Biphasic CO2 Absorption Process.

  Flow diagram of advanced biphasic carbon dioxide absorption process (BiCAP) - see the first, second, and paragraph in New Technology section for description.
Figure 3: Advanced Biphasic CO2 Absorption Process(BiCAP)

  photo a: Homogeneous solution - pale yellow liquid in a clear glass graduated cylinder. photo a prime: Upper carbon dioxide lean phase; lower carbon dioxide enriched phase - two immiscible liquids in a clear glass graduated cylinder. The upper liquid is the lean phase is clear yellow. The lower phase is CO2 enriched. The enriched phase is cloudy yellow and takes up the bottom two thirds of the liquid in the graduated cylinder.photo b: Heterogeneous solution - two immiscible liquids in a clear glass graduated cylinder. photo b prime: Upper carbon dioxide lean phase; lower carbon dioxide enriched phase - two immiscible liquids in a clear glass graduated cylinder. The upper liquid is the lean phase and is clear. The lower phase is CO2 enriched and is cloudy yellow. The enriched phase takes up the bottom half of the liquid in the graduated cylinder." title="photo a: Homogeneous solution - pale yellow liquid in a clear glass graduated cylinder. photo a prime: Upper carbon dioxide lean phase; lower carbon dioxide enriched phase - two immiscible liquids in a clear glass graduated cylinder. The upper liquid is the lean phase is clear yellow. The lower phase is CO2 enriched. The enriched phase is cloudy yellow and takes up the bottom two thirds of the liquid in the graduated cylinder.photo b: Heterogeneous solution - two immiscible liquids in a clear glass graduated cylinder. photo b prime: Upper carbon dioxide lean phase; lower carbon dioxide enriched phase - two immiscible liquids in a clear glass graduated cylinder. The upper liquid is the lean phase and is clear. The lower phase is CO2 enriched and is cloudy yellow. The enriched phase takes up the bottom half of the liquid in the graduated cylinder.
Figure 4: Phase separation (a/b) before and (a’/b’) after CO2 absorption