Measurement of CO₂ Diffusivity in Phase-Changing Aminosilicone CO₂ Capture Solvent

Abstract

The mass transfer performance of a phase-changing aminosilicone CO2 post-combustion capture absorbent has been characterized. The aminosilicone, 1,3-bis­(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane (GAP-0), rapidly transforms from a low-viscosity liquid into a friable solid upon exposure to gaseous CO2. Mass transfer performance of this absorbent was studied to inform design and scaleup of a CO2 capture process. The long-term mass transfer rate of CO2 gas through a solid GAP-0 carbamate salt layer into a quiescent pool of liquid GAP-0 was characterized using pressurized thermogravimetric analysis. This experiment led to an estimate of the CO2 permeability of the carbamate salt solid of 1.46 × 10–9 mol of CO2 m–1 s–1 atm–1. Given literature-reported values of CO2 solubility in silicone polymers, the CO2 diffusivity through GAP-0 carbamate salt was inferred to be approximately 4.39 × 10–11 m2/s. In parallel, the CO2 absorption rate into a spray of GAP-0 droplets was studied in a laboratory spray reactor. While the rate of CO2 absorption was anticipated to be limited by the rate of CO2 diffusion through a solid carbamate salt layer on the surface of a droplet, experimental results suggest that the GAP-0 droplets behave more like a liquid during spray absorption. The effective diffusivity of CO2 through these droplets was estimated to be approximately 6 × 10–9 m2/s.

Gas-liquid membrane contactors for carbon dioxide separation: A review

“…The use of relatively high CO2 absorption and desorption temperatures is also advantageous for improving process efficiency. Some aminosilicones, such as 1,3-Bis(3-aminopropyl)-1,1,3,3-tetramethyldsiloxane undergo a reversible phase change from liquid to solid as the carbamate salt forms during CO2 absorption [72][73][74]. As with the precipitating potassium carbonate system, a significant advantage in this case is that only the solid needs to be processed through the regeneration system.…”

Study on Preparation of an Oil Sludge-Based Carbon Material and Its Adsorption of CO2: Effect of the Blending Ratio of Oil Sludge Pyrolysis Char to KOH and Urea

“…Therefore, reducing CO 2 concentration is an important issue in this century. Currently, many different useful carbon dioxide capture technologies come into existence, such as ionic liquid circulation absorption, carbon dioxide hydrate separation, membrane separation, amine compound absorption, and chemical and physical absorption. − …”