Electrochemical separation of carbon dioxide from air: Symposium talk.

[NNadir]

Carl A. Koval, Dean Camper, Jessie Kieft, Richard
Noble, Mya Norman, Paul Scovasso

Ionic compounds that are liquids near room temperature (RTILs) have a number of properties (e.g. low volatility and high conductivity) which make them attractive as alternative solvents systems <1>. This presentation will discuss the use of RTILs for electrochemical separation of carbon dioxide from air, electrochemically-driven fluid pumping, and studies of electron transfer at liquid-liquid interfaces. One approach to carbon management is the separation of carbon dioxide from the atmosphere
(@350 ppm) and its concentration in a pure form for subsequent conversion to a liquid fuel (i.e. methanol) or for sequestration. The separation of carbon dioxide from the atmosphere at a sequestration point would save on transmission costs from the generation point and the use of atmospheric carbon dioxide to produce liquid fluids is a net zero green house gas load cycle for transportation fuels. Central to the success of these concepts is the need to separate and concentrate carbon dioxide with low energy cost. Electrochemically modulated complexation (EMC) can, in principle, selectively separate and concentrate carbon dioxide from the atmosphere with reduced energy consumption. Recently, we demonstrated that an EMC process involving reduction of 2,6-di-tert-butyl-1,4-benzoquinone in organic solvents and or in an RTIL can be used to separate carbon dioxide from nitrogen <2>. A key issue for improving EMC gas separation processes in RTIL’s is understanding what factors govern gas solubility in them. A simple model for predicting the solubility of carbon dioxide (and other gasses?) in RTILs will be presented.

Interest in microfluidics has stimulated recent interest in finding novel ways to pump fluids nonmechanically. One simple approach to this goal involves inducing volume changes in electrochemical
cell compartments by causing migration to occur through perm-selective membranes. Preliminary experiments demonstrating this concept in conventional electrolyte systems and in RTILs will be presented. Hydrophobic RTILs in contact with aqueous electrolytes represent a novel type of liquid-liquid interface. Values of interfacial potentials <3> developed at such interfaces will be reported and discussed.

<1> Paul Scovazzo, Ann E. Visser, James H. Davis, Jr.,
Robin D. Rogers, Carl A. Koval, Dan L. DuBois, and
Richard D. Noble, " Supported Ionic Liquid
Membranes and Facilitated Ionic Liquid Membranes”,
ACS Sym. Ser. (2002) 818, 69-87.
<1> Paul Scovazzo, Joe Poshusta, Daniel DuBois, Carl
Koval, Richard Noble, "Electrochemical Separation
and Concentration of <1% Carbon Dioxide from
Nitrogen," J. Electrochem. Soc., (2003) in press.
<2> Heather O. Shafer, Torri L. Derbach, Carl A. Koval,
" Electron Transfer Reactions of Hydrophobic
Metallocenes with Aqueous Redox Couples at Liquid-
Liquid Interfaces. Part 1. Solvent, Electrolyte
Partitioning and Thermodynamic Issues" J. Phys.
Chem. B., (2000) 104, 1025-32.
Abs. 1395, 204th Meeting, © 2003 The Electrochemical Society, Inc.

That's a talk I would have loved to have attended.

[leftupnorth]

1. Me too

sounds interesting. This is the kind of thing that may be the key to reversing global warming. Sequestration of Carbon is the name of the game.

[NNadir]

2. I don't envision this as a sequestration scheme.

I view it as a means to convert hydrogen into clean liquid fuels.

It is relatively straight forward to produce hydrogen from a myriad of sources. What is not straight forward is using the hydrogen. The hydrogenation of carbon dioxide (and monoxide) is well understood and is an excellent way to make liquid fuels like my favorite, DME. The big problem is getting the carbon dioxide in a sustainable way. Capturing carbon dioxide from fossil fuel sources for the purpose of this hydrogenation is not really a winner, since the net reaction is still the conversion of carbon or hydrocarbons to carbon dioxide. Ideally the best way of getting carbon dioxide would be to get it the same way plants get it - from the air.

Sequestration, in my opinion, is a pipe dream. There is no industrial evidence that it will work on anywhere near the scale needed. It's used as a prop for the coal, oil and gas industries as a salve. They have no serious intention whatsoever of making it work in my view.

[eppur_se_muova]

5. I would call this carbon RECYCLING, not sequestration.

Sequestration is sweeping it under the rug. Sooner or later the rug will lift.

[Odin2005]

3. Hmmm, If we ever get fusion...

This would be an excellent way to get carbon for plastics, since the only other source of carbon for plastics besides oil is biomass. If we ever get fusion we would have enough clean energy to make this economically viable, and this method would be far more enviromentally friendly then getting the carbon from crops.

[NNadir]

4. Fusion will not happen on a significant scale in the life time of anyone

now living.

The hydrogenation of carbon dioxide is possible right now using existing technology in a sustainable fashion.

We can produce sustainable energy. This is discussed in a Science paper which is available on line that I have referenced previously.

The thread is here: http://www.democraticunderground.com/discuss/duboard.php?az=view_all&address=115x59612

I don't agree with some of the stabilization wedges, some - like sequestration - being industrially unproved, but I note, as do the authors, that not all of the wedges are necessary.