Measuring the Absorption Rate of CO₂ in Nonaqueous CO₂‐Binding Organic Liquid Solvents with a Wetted‐Wall Apparatus

Abstract

The kinetics of the absorption of CO2 into two nonaqueous CO2-binding organic liquid (CO2 BOL) solvents were measured at T=35, 45, and 55 °C with a wetted-wall column. Selected CO2 loadings were run with a so-called "first-generation" CO2 BOL, comprising an independent base and alcohol, and a "second-generation" CO2 BOL, in which the base and alcohol were conjoined. Liquid-film mass-transfer coefficient (k'g ) values for both solvents were measured to be comparable to values for monoethanolamine and piperazine aqueous solvents under a comparable driving force, in spite of far higher solution viscosities. An inverse temperature dependence of the k'g value was also observed, which suggests that the physical solubility of CO2 in organic liquids may be making CO2 mass transfer faster than expected. Aspen Plus software was used to model the kinetic data and compare the CO2 absorption behavior of nonaqueous solvents with that of aqueous solvent platforms. This work continues our development of the CO2 BOL solvents. Previous work established the thermodynamic properties related to CO2 capture. The present paper quantitatively studies the kinetics of CO2 capture and develops a rate-based model.

Reinventing Design Principles for Developing Low‐Viscosity Carbon Dioxide‐Binding Organic Liquids for Flue Gas Clean Up

“…testing were performed for both thermal-and polarity-swingassisted regeneration (PSAR) CO 2 release modes. [10] This study revealed that 1-IPADM-2-BOL has the potentialt ob ea ne nergetically viable CO 2 -capture solvent, assuming viscosities could be reduced.…”

“…The liquid sample was regenerated in situ by raising the water bath temperature to 60°C‐80 °C and reducing the cell pressure using a vacuum pump (Edwards RV8). The operation of the cell was validated using a CO 2 BOL solvent with published viscosity and vapo–liquid equilibrium data …”

“…Various water‐lean solvent systems designed to minimize water content, including task‐specific ionic liquids (TSILs), phase‐change materials, nanomaterial organic hybrids, aminosilicones, and siloxylated amines, have been developed as alternatives to the energy‐intensive aqueous amine‐based solvents. Although the chemical reactivity of each of these water‐lean solvent classes is different, they are projected to be drop‐in replacements for aqueous solvents, yet operate in presence of little or no water . Water‐lean solvent systems have been projected to offer ∼40 % reduction in energy requirements compared to aqueous amines or other water‐based solvents because of lower specific heat capacities and lower water content .…”

“…We recently performed a comprehensive study on 1‐[(1,3‐dimethylimidazolidin‐2‐ylidene)amino]propan‐2‐ol (1‐IPADM‐2‐BOL) to measure physical, thermodynamic, and kinetic property data. Additionally, Aspen Plus modeling and bench‐scale testing were performed for both thermal‐ and polarity‐swing‐assisted regeneration (PSAR) CO 2 release modes . This study revealed that 1‐IPADM‐2‐BOL has the potential to be an energetically viable CO 2 ‐capture solvent, assuming viscosities could be reduced.…”

“…Although the chemical reactivity of each of these water-lean solvent classes is different, they are projected to be drop-in replacements for aqueous solvents, yet operate in presence of little or no water. [10] Water-leans olvent systemsh ave been projected to offer~40 %r eduction in energy requirements compared to aqueous amineso ro ther water-based solvents because of lower specifich eatc apacities and lower water content. [11,12] In the past decade, our group has focusedo nt he development of the water-lean solvent system known as CO 2 -binding organic liquids (CO 2 BOLs).…”