Electrochemical Separation and Concentration of <1% Carbon Dioxide from Nitrogen

Abstract

Low energy separations for <1% CO2 gases would benefit gas treatment and CO2 sequestration. Theoretically, electrochemical pumping can separate and concentrate CO2 from the atmosphere or other gases with <1% CO2 at significantly lower energy cost than current systems. Principles of electrochemical pumping for CO2 separations are discussed and results for both organic solvent and ionic liquid working fluid systems are presented. Due to the large quantities of gases requiring processing during the separation/concentration of <1% CO2 gases, this work looked at solvents with negligible vapor pressures, specifically propylene carbonate and the room-temperature ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate. Other important parameters, as illustrated by the data and models presented, are low CO2 solubility in the solvent, high CO2 carrier solubility, CO2 binding constants, and the CO2 carrier’s electrochemistry. Reported is the electrochemical pumping of CO2 from 0.5% (in nitrogen) to 100%, a 200-fold increase in partial pressure, using the CO2 carrier 2,6-di-tert-butyl-1,4-benzoquinone in a propylene carbonate solution. The ratio of CO2 moles pumped per electron mole was 0.43. The models determined the optimal CO2 solubility in the solvent and the required redox swing in the CO2 binding constants of the carrier. © 2003 The Electrochemical Society. All rights reserved.

Push or Pull? Proton Responsive Ligand Effects in Rhenium Tricarbonyl CO2 Reduction Catalysts

“…Under identical conditions, i c /i p for [Re( t Bu 2 bpy)(CO) 3 Cl] is 4.7 at -2.05 V. With 5% water added, catalytic current is attenuated in contrast to the effects of water on catalysis using [Re(bpy)(CO) 3 Cl] and of weak acids on related complexes. [52][53][54] The appearance of two slopes in the catalytic CO 2 reduction wave using [Re(4DHBP)(CO) 3 Cl] is explained by the two pathways for formation of [Re(4DHBP-2H + )(CO) 3 (CO 2 )]on the CV timescale (Scheme 1, species E). OHand CO 2 , the catalytic waveform is similar but shifted positive by ca.…”

Solubility of carbon dioxide and ethane in three ionic liquids based on the bis{(trifluoromethyl)sulfonyl}imide anion

“…The solubility of carbon dioxide in a variety of ILs has been determined at low pressures [1][2][3][4][5][6][7][8][9][10] and high pressures (up to 73 MPa) [11][12][13][14][15][16][17][18][19][20][21][22][23][24]. In particular, the system (carbon dioxide + [C 1 C 2 Im][NTf 2 ]), also investigated in this work, was studied by several authors [7][8][9][10]14,17].…”

Transport of carbonate ions through supported liquid membrane by using Alamine 336 and trioctylphosphine oxide as carriers

“…The solubility of CO 2 was studied through the supported ionic liquid membranes (15). The attempt to separate the acidic gases CO 2 , SO 2 , and NO x with supported ionic liquid membranes involved electrochemical modulated complexation (16). The CO 2 by carbonate formation was explored for separation of CO 2 through supported ion liquid membrane (17).…”