Novel Thermomorphic Biphasic Amine Solvents for CO2 Absorption and Low-Temperature Extractive Regeneration

Abstract

The key challenge in amine-based CO 2 capture from flue gases is to reduce the energy consumption required for solvent regeneration. Lipophilic amines exhibit a thermomorphic phase transition upon heating, giving rise to autoextractive behavior, which intensifies desorption at temperatures well below the boiling point of aqueous solutions. The low regeneration temperature of less than 80°C together with the high cyclic CO 2 loading capacity of ∼0.9 mol CO 2 mol absorbent -1 of such thermomorphic biphasic solvent (TBS) systems permit the use of low-value and even waste heat at temperatures below 100°C for desorption. In order to reduce the exergy demands still further, techniques for enhancing CO 2 release using extractive regeneration with inert solvent addition were investigated at temperatures of 40-50°C to permit the use of waste heat at temperatures of ∼70°C or less. The regeneration of 3 M absorbed lipophilic amine solutions with 0.93 mol mol -1 CO 2 loading by using various additional solvents and the evaluation of the extractive performance in multiple-stage crosscurrent and countercurrent configurations indicated the promise of adding certain hydrophobic solvents to enhance the low-temperature regeneration of TBS absorbents.

1-Cyclohexylpiperidine as a thermolytic draw solute for osmotically driven membrane processes

“…Previous models of thermolytic draw solute removal [37] may have been overly optimistic in light of more recent experimental results [18,19]. The concentration dependence of the CO 2 removal from amines is better highlighted in the carbon capture literature [38][39][40][41][42][43]. In the case of DMCHA at full concentration it started degassing as early as 25°C, requiring viscosity measurements to be made at 15°C, however as will shortly be illustrated DMCHA requires nearly reflux conditions to fully remove the CO 2 content.…”

Concentration dependent speciation and mass transport properties of switchable polarity solvents

“…This unique character suggests relevance to a variety of applications including extractions (natural products, 2 algal oils, 3-7 biomass, 8 and oil sands 9 ), pyrolysis oil fractionation, 10 biomass pretreatment and fractionation, 11,12 carbon capture, [13][14][15][16][17][18][19][20] reaction media, and osmotically driven membrane processes (ODMP), such as forward osmosis (FO). For example, tertiary amines, which are charge neutral, can become ionic in the presence of water and an acid gas, such as CO 2 .…”

Nanofluids Containing MWCNTs Coated with Nitrogen-Rich Plasma Polymer Films for CO2 Absorption in Aqueous Medium

“…The absorption capacity of these NFs is low compared to other technologies available. Common solutions of alkanolamines can go up to 4 mol of CO 2 L −1 , with concentrations of 5 mol L −1 of the alkanolamine . In the current study, the maximum obtained is 0.067 mol of CO 2 L −1 of NF.…”