Saturday, September 16, 2006

A simple question.

A simple question popped into my simple mind the other day. If, considering our considerable skill and technical expertise in chemical engineering – why is it apparently not possible to run CO2 gas through a catalytic converter or something, and just split it up into Carbon and Oxygen?

Would solve a hell of a lot of problems if someone could come up with the answer to that.

(Haven't spent much time looking, but the only reference to someone working on this problem that have been able to find - so far - is this one.


dining_philosopher said...

Why complicate matters? Just plant more trees......

Davo said...

.. or stop knocking them down ..

Anonymous said...

Several problems with this:

Major: The link is describing Rh catalysts for CO2 -> CO (aka carbon monoxide) which is toxic, and slowly oxidizes as it rises into the upper atmosphere to form CO2 again. We get right back where we started. (This is how cars produce CO2 in the first place. For the most part it is actually CO that comes out of cars in the first place which then "degrades" to CO2)

Minor ones:

1. Requires Rhodium which is pretty expensive

2. The reaction also requires PF3 gas (which I'm pretty sure is toxic and reactive) and would have to be contained in a vessel of some sort:- retaining the PF3 gas while taking in CO2 and expelling CO would require some specialist (read expensive) engineering

3. The pathway is incomplete at room tempreture (ie. in the open air where cars usually operate) goes through Rh(PF3)1(CO)1,2 which sounds pretty damn nasty in itself; BUT "elevated" tempretures are needed to complete the conversion to CO.

The paper does note "potential" for low tempreture operation. They don't say what they mean by low tempreture but since they refer to a subsiduary result at 150C perhaps that's what they mean. This will require energy input and since you're in a car the only place to get it is from the engine (aka lower fuel efficiency)

4. Whether the reaction would even work properly in the prescence of all the other stuff in exhaust gases is an open question.

Bottom line: Hard to do, pointless, expensive and we'll burn more oil doing it.

I'd see this as describing a potential industrial process for production of CO in industrial chemistry - not a mass market process or anything near it. Even if it could be mass fitted to cars, it's not solving the problem.

Davo said...

Yup, Anon. I should have said 'simple question - not so simple answer.' If it was éasy', I guess someone would have developed the process by now. Also, i wasn't thinking about 'motor vehicles' so much, as the generation of electricity. Unless or until we can get ppl to turn off their electric toothbrushes or tumble driers, the generation of electricity is one of the prime contributors to the over abundance of CO2. Finding ways to convert our present generation of electricity production is a major challenge to the economics of "modern" society.