Carbon Sequestration via Haematite

[sethoflagos]

Getting shot of huge amounts of CO₂ requires proportionately huge quantities of sequestrant. One sequestrant that could fit the bill is Fe₂O₃ (haematite) that comprises the much of the extensive banded iron formations which are globally distributed. My thoughts on this drifted to the following schemata which needs input from a proper chemist to evaluate.

Fe₂O₃ + 6HI_(aq) > 2FeI₂ + 3H₂O + I₂                                  Note Fe³⁺ reduced to Fe²⁺ 

4NaOH_(aq) + 2CO₂ > 2Na₂CO₃ + 2H₂O                            Stripping process from rich CO₂ stream

2FeI₂ + 2Na₂CO₃ > 2FeCO₃ + 4NaI                                  Precipitation of siderite (desired product) for anaerobic disposal

4NaI_(aq) + 4H₂O > 4NaOH_(aq) + 2H₂ + 2I₂                        Electrolytic regeneration of NaOH

H₂O > H₂ + ¹/₂O₂                                                                Further electrolysis of NaOH_(aq) to balance H₂ demand 

3H₂ + 3I₂ > 6HI                                                                  Regeneration of HI (fuel cell?)

The overall reaction sums to

Fe₂O₃ + 2CO₂ > 2FeCO₃ + ¹/₂O₂

... which I'm sure is endothermic but not I think in the ballpark of the exothermy of carbon combustion.  

What are the howlers I need to address? Is there a better reducing agent than iodide (eg scrap iron)? Any other positive input welcome of course.

[chenbeier]

Weak points.

Fe₂O₃ + 6HI_(aq) > 2FeI₂ + 3H₂O + I₂                              Note Fe³⁺ reduced to Fe²⁺

Iodine is expensive

2NaOH_(aq) + CO₂ > Na₂CO₃ + H₂O   

Ok      

FeI₂ + Na₂CO₃ > FeCO₃ + 2NaI     

FeCO3  will be oxidised by oxygen from air  back to Fe2O3. Not stable process.

2NaI_(aq) + 2H₂O > 2NaOH_(aq) + H₂ + I₂       

Electrolytic regeneration of NaOH

This will have side reaction to NaIO3

H₂O > H₂ + ¹/₂O₂                                                            

Further electrolysis of NaOH_(aq) to balance H₂ demand 

H₂ + I₂ <=> 2HI     its equilibrium reaction at high temperature 712 K. Nothing for a fuel cell. 

The energy what is used produces more CO2, what you can probably absorb.       

 

PS: I corrected also some of the equations.                                            

Edited July 18, 2023 by chenbeier

[studiot]

9 hours ago, sethoflagos said:

Getting shot of huge amounts of CO₂ requires proportionately huge quantities of sequestrant. One sequestrant that could fit the bill is Fe₂O₃ (haematite) that comprises the much of the extensive banded iron formations which are globally distributed. My thoughts on this drifted to the following schemata which needs input from a proper chemist to evaluate.

Fe₂O₃ + 6HI_(aq) > 2FeI₂ + 3H₂O + I₂                                  Note Fe³⁺ reduced to Fe²⁺ 

4NaOH_(aq) + 2CO₂ > 2Na₂CO₃ + 2H₂O                            Stripping process from rich CO₂ stream

2FeI₂ + 2Na₂CO₃ > 2FeCO₃ + 4NaI                                  Precipitation of siderite (desired product) for anaerobic disposal

4NaI_(aq) + 4H₂O > 4NaOH_(aq) + 2H₂ + 2I₂                        Electrolytic regeneration of NaOH

H₂O > H₂ + ¹/₂O₂                                                                Further electrolysis of NaOH_(aq) to balance H₂ demand 

3H₂ + 3I₂ > 6HI                                                                  Regeneration of HI (fuel cell?)

The overall reaction sums to

Fe₂O₃ + 2CO₂ > 2FeCO₃ + ¹/₂O₂

... which I'm sure is endothermic but not I think in the ballpark of the exothermy of carbon combustion.  

What are the howlers I need to address? Is there a better reducing agent than iodide (eg scrap iron)? Any other positive input welcome of course.

Something like this may have happened in the past when the Earth's atmosphere and was known as the great rust event, when much of the widely distributed oxides ov iron were formed.

https://www.amnh.org/exhibitions/permanent/planet-earth/how-has-the-earth-evolved/banded-iron-formation

 

+1 for trying to think out of the box.

 

However I am firmly of the opinion that rather than employing more big business at great cost to clean up after the activities of other big business, it would be better if big business did not create so much carbon dioxide in the first place.
Both the creation and clean up only benefit the greed of such business; the vast mojority continue to suffer the cost and pay for the enrichment of the few.

[sethoflagos]

5 hours ago, chenbeier said:

Iodine is expensive

Not excessively so I think and it's recycled within the process. 

5 hours ago, chenbeier said:

FeCO3  will be oxidised by oxygen from air  back to Fe2O3. Not stable process.

As stated in the OP, siderite must be handled and stored in anaerobic conditions.

5 hours ago, chenbeier said:

This will have side reaction to NaIO3

Could be critical. Is there a dynamic equilibrium balance between iodide/iodate which could regenerate iodide when its concentration falls?

5 hours ago, chenbeier said:

H₂ + I₂ <=> 2HI     its equilibrium reaction at high temperature 712 K.

Not sure what you're trying to say here.

5 hours ago, chenbeier said:

The energy what is used produces more CO2, what you can probably absorb.

Solar electrical power? 

[chenbeier]

14 minutes ago, sethoflagos said:

1.Not excessively so I think and it's recycled within the process. 

2.As stated in the OP, siderite must be handled and stored in anaerobic conditions.

3.Could be critical. Is there a dynamic equilibrium balance between iodide/iodate which could regenerate iodide when its concentration falls?

4.Not sure what you're trying to say here.

5.Solar electrical power? 

1. The recycling process and its chemical and solvent makes it expensive.

2. How to avoid the oxygen. You have first an aqueous process if the iron iodide reacts with the sodium carbonate. The water contains everytime some air. How to get rid of it.

3. At alcaline conditions you have at anode an oxidation process.  Iodide to iodine and hydroxide to oxygen and together forms iodate.

4. The iodine hydrogen reaction takes place at 712 K efficiently. Again a lot of energy what I needed. I think a fuel cell will not run at this temperature.

5. Its not the matter of the source of Power.

 

 

Edited July 18, 2023 by chenbeier