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Carbon BiCarbonate

Coke plus Carbonic Acid
  [vote for,

In a previous Idea I mentioned that I think that a key to dealing with excess carbon dioxide in the air is to add water and let it form carbonic acid (see link). Making and storing a lot of it in pure form is problematic, however.

It would seem logical (as was pointed out in at least one annotation to that older Idea) to chemically combine the carbonic acid with something, to stabilize it. Unfortunately, ordinary suggestions such as using elemental calcium (calcium carbonate exists naturally in vast quantities, and is typically known as "limestone") suffer from the problem is that it takes significant energy to obtain elemental calcium, which somewhat defeats the purpose of dealing with the side-effect (carbon dioxide) when generating energy in the first place.

However, recently I had a DUH!!! insight.

Elemental carbon is widely available in the form of "coke", normally used in the manufacture of steel. In a way, coke is simply purified coal (which is largely also elemental carbon). We mostly burn this carbon to obtain energy, of course. BUT!! We don't necessarily have to burn ALL the carbon that we purify!

We could ramp up the production of purified carbon, meaning we now have more coke available than is currently used for steelmaking and other processes. We now begin using this newly produced purified carbon to chemically react with the carbonic acid (chemical formula H2CO3) that we get by simply mixing carbon dioxide and water.

In theory, we could have three possible chemical reactions: One atom of Carbon
+ (2 molecules of carbonic acid) -> Carbon Carbonate
formula C(CO3)2, with 4 hydrogen atoms released. OR
+ (4 molecules of carbonic acid) -> Carbon BiCarbonate
formula C(HCO3)4, also with 4 hydrogen atoms released. OR
+ (3 molecules of carbonic acid) ->
formula C(CO3)(HCO3)2, with 4 hydrogen atoms still released. This is a combination of carbonate and bicarbonate, and I don't know what its proper chemical name might be.

Some quick Googling didn't make it obvious whether or not any of these chemical compounds can actually exist. My guess is that we might need to find a catalyst to make these reactions happen, but if we can make them happen, then the result will be worth it.

Note that The Reaction To Prefer is the second, because it allows one atom of carbon to lock away 4 molecules of CO2 (remember that one CO2 plus one H2O makes one molecule of carbonic acid). AND we get some free* hydrogen fuel, too!

*Well, probably semi-free hydrogen. It is likely that we might have to add a bit of energy to make any of these reactions "go" (and another reason why we might need a catalyst). But I'm pretty sure less energy will be needed, than we can get back from burning that hydrogen with ordinary atmospheric oxygen.

Vernon, Jun 08 2011

PolyCaracid Polycaracid
As mentioned in the main text; it is actually in the annotations of this linked Idea, where I conclude that simply making/storing carbonic acid might be worthy all by itself. [Vernon, Jun 08 2011]

Table of ElectroNegativities http://chemed.chem....ativities-1060.html
As mentioned in an annotation. [Vernon, Jun 08 2011]

Dimethyl Carbonate http://en.wikipedia.../Dimethyl_carbonate
What it says... [goff, Jun 08 2011]

Dimethyl Sulfoxide http://en.wikipedia.../Dimethyl_sulfoxide
Structurally identical with Dimethyl Carbonate, except that 1 Carbon atom is replaced with a Sulfur atom. I'm only adding this link because of the similarity, and the fact that dimethyl sulfoxide has some properties that I always thought were "cool!" [Vernon, Dec 10 2013]


       You're essentially describing esterification, and it would use up all the energy you got from producing the CO2 in the first place, so it would be a net loss.   

       Esters are, however, very useful as petrochemical feedstocks.
8th of 7, Jun 08 2011

       [8th of 7], I'm quite sure you are mistaken about your energy statements. Look at the Table of ElectroNegativities (link), and see that the value for Hydrogen is 2.1. (Since writing it down I've had time to think about it more closely.)   

       In general, any chemical reaction involving an acid is a reaction in which certain "available" hydrogen atoms in the acid will be released in exchange for some other element. However, the other element needs to have a lower number than Hydrogen's 2.1. So Gold and Platinum are not normally affected by acids, because their numbers are higher. (Exceptions are likely due to the presence of a catalyst.)   

       Also, in general, the amount of energy that is released when an acid does its thing depends on the difference between Hydrogen's 2.1 and the number of the other element --Calcium is 1.0, a pretty big difference, so a fair amount of energy can be released.   

       But as mentioned in the main text, Calcium is normally found already chemically combined. Those chemical bonds must be broken to obtain the pure element, which might then be reacted with an acid. This is NOT true with respect to Carbon; it can naturally occur (graphite, for example) in a chemically uncombined state. And coal is basically a mixture of uncombined and combined Carbon atoms; the coking process simply separates the two. (The combined Carbon is still combined, in all the chemicals found in "coal tar".)   

       As you can see, though, the ElectroNegativity value for Carbon is 2.5, which means an acid is not likely to be able to affect it without the help of a catalyst (and more particularly, an energized catalyst).   

       The reaction that I'm proposing will basically cause an Oxygen atom to trade its chemical bond with a Hydrogen for a Carbon, and, yes, this reaction will require some energy equal to the difference between Hydrogen's value of 2.1 and Carbon's value of 2.5. But the Hydrogen that is released can then be combined with extra Oxygen (from the atmosphere), which will release an amount of energy that is represented by the difference between Oxygen's value of 3.5 and Hydrogen's value of 2.1 (lots more energy than we just used to catalyze the other rection!).   

       The water produced by that reaction can then be recycled with respect to making more carbonic acid and making more Carbon Carbonate or Carbon BiCarbonate. The NET effect, actually, is that we are obtaining energy equal to oxidizing the purified Carbon that we produced specifially for this proposed reaction. But we are oxidizing it in a way that lets us sequester the waste product --Carbon Carbonate is much too massive a molecule for it to be anything other than a solid (and the BiCarbonate would be even more massive).
Vernon, Jun 08 2011

       In looking at the Table of ElectroNegativities, I note that Sulfur also has a value of 2.5. And I recall that Sulfur also is widely available in the naturally uncombined state. So, we could also look for a catlyst to combine Sulfur with carbonic acid, thereby producing Sulfur Carbonate or Sulfur BiCarbonate (and releasing Hydrogen for recycling, as with Carbon).
Vernon, Jun 08 2011

       Wouldn't carbon carbonate be acetic acid?
bungston, Jun 08 2011

       [bungston], no, the formula for acetic acid is CH3COOH, which starts with a central Carbon, which has a methyl (CH3) group attached to it by a single bond, and also has a single Oxygen double-bonded to it, and finally has a hydroxyl (OH) group attached to it by another single bond. It's acidity derives from the Hydrogen in the hydroxyl group.   

       Nor is it an ester. There are a wide variety of compounds called "esters", but all of them have rather more Hydrogen in their molecular structures than even the the proposed Carbon BiCarbonate.
Vernon, Jun 08 2011

       Well, what we need is a chemist to explain why none of the "carbon carbonates" exist or have names.   

       What structural formula do you imagine they would have?
MaxwellBuchanan, Jun 08 2011

       I think you are talking about organocarbonates Vernon, of which there are many. e.g Dimethyl Carbonate which is a carbonate ester (CH3OCO2CH3), don't know what your one is but it looks like one of these to me. Try Wikipedia on organocarbonates.
goff, Jun 08 2011

       not quite what you are talking about Vernon, but have you conciderd useing charcoal? from my old chemistary book i see that 1 volume of charcoal will absorb up to 171 volumes of easely liquifide gas. and that cabon dioxide can be liquifide at +15 by 52.1 atmospheres. also its more active than coke
j paul, Jun 08 2011

       [goff], I'm not denying that organic carbonates could exist, nor am I claiming that no esters can be carbonates. I'm simply denying that Carbon Carbonate or Carbon BiCarbonate qualifies as either. I do note that some care has to be used in distinguishing between "carbon compounds" and "organic compounds", since all of the latter are also the former. But quite a few carbon compounds (such as CO2 or "graphene") are not considered to be "organic"; they are as "inorganic" as H2O.   

       Both Carbon Carbonate and Carbon BiCarbonate would be inorganic compounds. In terms of molecular structure, to answer [MaxwellBuchanan]'s question, we first must keep in mind the structure of carbonic acid. It has a central Carbon atom to which one Oxygen is attached by a double-bond, and two hydroxyl (OH) groups are attached by single bonds. The Hydrogens in those hydroxyl groups are available for getting exchanged for other atoms (like Calcium when Calcium Carbonate forms).   

       For Carbon Carbonate, now our central Carbon atom is the one that we wish to chemically combine with carbonic acid. Two of this atom's four available bonds would interact with the two hydroxyl groups of one carbonic acid molecule, and the other two bonds of the central Carbon would interact with the two hydroxyl groups of a second carbonic acid molecule.   

       The result is that our central Carbon is single-bonded to each of 4 Oxygen atoms. These were the Oxygens that had been part of the hydroxyl groups, and the 4 Hydrogen atoms that are released, as described in the main text, also had been part of the hydroxyl groups.   

       For Carbon BiCarbonate, our central Carbon gets involved with only one hydroxyl group from each of 4 carbonic acid molecules. Again it becomes surrounded by 4 Oxygens that are single-bonded to it, and again 4 Hydrogens from those hydroxyl groups get released.   

       In the third reaction mentioned in the main text, our central Carbon gets involved with both hydroxyl groups of one carbonic acid molecule, and with one hydroxyl group each of two other carbonic acid molecules. So again the central Carbon is surrounded by 4 Oxygens that are single-bonded to it, and again 4 Hydrogens get released.   

Vernon, Jun 09 2011


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