Thermal Chemistry of Carbon Dioxide Reduction: An Obscure Point.

Self cleaning ovens are coated with ceric oxide, and one factor in the way they work is that they are Boudouard catalysts, a Boudouard catalyst, being a catalyst that causes the following reaction to take place: C + CO₂ <-> 2 CO. The bidirectional arrow (which properly should be used for all chemical reactions) refers to the fact that the reaction can go in either direction, and the direction it chooses to go is a function of concentration and temperature.

If the carbon monoxide formed reacts with oxygen on the surface, it will oxidize to form carbon dioxide, the famous dangerous fossil fuel waste that is continuously being dumped into the atmosphere, and for which there is no permanent repository.

This reaction is 2CO + O₂ <-> 2CO₂.

The net reaction is of course, just combustion. C + O₂ <-> CO₂.

As a catalyst, the ceric oxide is not consumed in this reaction although it is involved in reaction intermediates. Cerium, unlike other lanthanides has two oxidation states that are commonly stable in air, +3 and +4, and the catalytic reaction almost certainly involves the reduction of the +4 oxide by carbon to the +3 oxide, and reoxidation by air, giving the original oxide.

Recently in this space, I wrote about the carbon dioxide radical anion, which is involved in schemes to electrolytically reduce carbon dioxide to the monoxide, the monoxide being useful for chemical synthesis that might replace oil. I also noted that this anion can be formed radiolytically, by the interaction of high energy radiation, gamma, x-rays, and short wavelength UV.

http://www.democraticunderground.com/discuss/duboard.php?az=view_all&address=228x56433">An Interesting Chemical Radical Species: The Carbon Dioxide Anion.

One possible fate of this ion is to produce oxalate, which may be thought of a kind of dimer of CO₂.

Many years back, nuclear chemists studied the decomposition (thermal) of cerium (and other lanthanide) oxalates to give CO gas and carbon dioxide gas. This type of reaction is known as a disproportionation reaction ^-O₂CCO₂^- <-> CO + CO₂. A disproportionation reaction is one in which a substance, usually an element but sometimes an organic compound, oxidizes itself and reduces itself at the same time.

The reference for a discussion of these reactions, which also take place with neodymium, samarium and praesodymium, but not europium, is discussed in J. Inorg. Nucl. Chem., 1961, Vol. 22, pp. 39 to 48.

The reactions were conducted under vacuum, but what they suggest is that lower oxidation states may exist for neodymium and praesodymium. (A lower oxidation state of samarium is well known.)

I have no idea whether anyone has exhaustively studied that point.

It's esoteric, but cool, since any mechanism for the reduction of carbon dioxide to its monoxide is of interest.

I like to advocate for the importance to humanity of nuclear chemistry and chemistry in general, vastly under appreciated (by the public) sciences that are critical to the future of humanity.

Interesting point for discussion.

You're in on it, aren't you? You're plotting to increase CO so you can put people into comas and sell their organs!

Dr. Wheeler is onto your scheme!

...I'm sure I can be convinced to confess to anything.

Have copied and saved.

Chemistry can be both good and bad when used by humans.
We have unwittingly added lots of toxins to the planet because of lack of foresight of the consequences of new chemical compounds produced by humans.

On the other hand, chemistry may hopefully find ways to clean up the messes of previous chemistry errors.

Digital photography replacing film photography has meant that the toxic chemicals used to produce film are no longer used. However, chemicals are used in the manufacture of digital sensors and boards used in cameras, and some of these have been known to cause cancer.

In the old days I'd take a few pictures, drop the film off at Costco, and get prints back. For most of these pictures that was the end of the line -- the photos would go in a scrapbook or a box and the silver would be recycled. My film cameras are ancient too, and were built to last so long as anyone cared to keep them in good repair, thirty, forty, fifty years, or longer. I've got cameras older than that still going strong. Occasionally I'd get a picture on film that was so good I'd make extra prints or enlargements, but that would, again, be the end of it.

With digital photos I take many more photos, I fuss with them on the computer using energy the entire way, I make prints and reprints any time I want and more often than I used to because I don't have to go digging through boxes of negatives. And some of my pictures go up on photo sharing sites where friends and family look at them using energy the entire time.

I also (oh no!) use disposable batteries when my two sets of rechargeable run out and I still have pictures to take. The batteries in my old film SLR last forever, what happens is that I'll get nervous and buy a spare after a few years, but I won't get around to needing it for a few more years. And the camera works without batteries too, but I have to set the exposure manually. Not difficult once you've practiced a bit.

I do like digital however. Mistakes and bad shots cost nearly nothing. But the cameras don't seem to last long. I've never had a digital camera fail and be worth repairing.

Several factors besides the end user's use need to be considered.

Among these are the cost of trucking the physical film components, as well as starting materials, the cost of chemical synthesis of the starting materials, such as cellulose, fixers, developers, etc, the refining of metals such as silver and a host of similar factors, the inevitable issue of waste disposal.

I would guess that photography has never been environmentally benign.

One of the interesting factors was raised by my boy today, which is the permanence of the images. We may lose many images if the software becomes obsolete or as images degrade on storage or copying errors.

But of course, cellulose is hardly stable forever. Probably the most stable images were on glass plates.

Who has a 3.5" floppy drive anymore?
Who has a 5.25" floppy drive?
Who has a reader for data carrying cassette tapes? (common around 1980)

Outside of how long it takes for digital disks/etc to degrade, we also need the systems required to READ that data. A disk is worthless without a functioning disk reader.

But the problem is getting deeper.

I showed a kid a 5.25" floppy disk the other day. I thought it would be fun to show them how floppy disks got the name 'floppy.' But the joke was on me. This kid had never heard of floppies. He considered CD's outdated. Music comes off the internet, right to the MP3 player. 'Storage', as a separately needed entity, is for him an archaic concept.

There is a strong chance that much of the information from the period between 1980 and 2005 (or so) is going to be lost. If it hasn't been copied to a long lived server, or written into a book, it may well be lost forever.