Made out of thin air: Fixation of CO2 through iridium catalyzed hydrosilylation

October 3, 2012

(Phys.org)—Carbon dioxide could be a useful alternative source of carbon for the chemical industry. It is inexpensive, is supplied in abundance by nature, and would help to reduce the consumption of fossil fuels. In addition, it would significantly improve the carbon footprint of fuels and chemical products. The largest barrier to this process is the high stability of the carbon dioxide molecule. In the journal Angewandte Chemie, Spanish researchers have now introduced a new process that traps carbon dioxide in the form of silyl formates, which are silicon-containing formic acid esters.

The of CO2 to formic acid (HCO2H) is an area of CO2 extraction that is being intensively researched. In the chemical industry, formic acid is used as a starting material for many products, with applications including agriculture, food technology, and the leather goods industry. Most interestingly, it could be used as a hydrogen- for fuel-cell-driven vehicles.

Although a number of catalytic processes for the production of formic acid from CO2 have been developed, none of them have been implemented industrially. The reaction is an equilibrium that significantly favors the . In order to hinder the constantly running reverse reaction, the formic acid must be trapped—in the form of salts, adducts, or derivatives—in order to remove it from the equilibrium.

A team led by Francisco J. Fernández-Alvarez and Luis A. Oro at the University of Zaragoza has now developed a new catalyst that allows carbon dioxide to be converted and trapped as a silyl formate. These compounds can be used for the production of silicone polymers and as reactive intermediates in organic syntheses. It is also easily possible to release formic acid from the silyl formate.

The new reaction, which the researchers have been able to carry out on a gram scale, occurs under very mild reaction conditions. It is highly selective and delivers a high turnover, works without a solvent and produces no waste products. The carbon dioxide is reduced by heptamethyltrisiloxane. At the heart of the reaction lies a specially developed iridium catalyst that is formed in situ from an air- and water-stable precursor.

Explore further: Continuous hydrogenation of carbon dioxide to pure formic acid in supercritical CO2

More information: Luis A. Oro, Effective Fixation of CO2 by Iridium-Catalyzed Hydrosilylation. Angewandte Chemie International Edition. dx.doi.org/10.1002/anie.201206165

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10 comments

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daqman
5 / 5 (5) Oct 03, 2012
Widespread catalytic conversion of atmospheric CO2 into useful organic chemicals has been underway for some time. In particular the use of solar energy to facilitate the reaction has been very successful.

The infrastructure for such organic chemical production is readily visible in most countries of the world, they are called plants.

Couldn't resist.
nkalanaga
3 / 5 (1) Oct 03, 2012
True, but plants are optimized to produce more plants. It would be nice if we could do the same thing to produce other products. Also, plant photosynthesis is relatively inefficient by industrial standards do to the amount of energy required to maintain the plant itself. relatively little finished product (seeds, etc) is produced compared to the energy collected.

I did like your comment, though, and it is true.
dnatwork
5 / 5 (1) Oct 03, 2012
But no one will invest in plants because everyone knows that money doesn't grow on trees.

Seriously, though, the only way global warming will be addressed is if the people who have money now can make more money off of solving the problem than from making it worse.
Eikka
5 / 5 (2) Oct 03, 2012
Also, plant photosynthesis is relatively inefficient by industrial standards do to the amount of energy required to maintain the plant itself.


Same goes for solar panels, mind you.

The amount of energy required to sustain the industry that makes, installs and maintains the solar infrastructure is a huge part of the energy they produce, giving just 6-7 times more energy than the energy you spent.

Roland
1 / 5 (1) Oct 03, 2012
Wikipedia: "...one of the rarest elements in the Earth's crust, with annual production and consumption of only three tonnes."
Eventide
5 / 5 (1) Oct 03, 2012
Roland you right. I just wish you included the key word "iridium" in your post because it certainly is not abundant like silicon is. If they can develop an alternative to an iridium catalyst that is derived from abundant materials and can be retrofitted in all running cars and industrial plants and to suck CO2 from the atmosphere, now that will be worth reporting about and doing.
Chromodynamix
5 / 5 (1) Oct 04, 2012
Plenty of Iridium in asteroids as the dinosaurs will attest!
antialias_physorg
5 / 5 (1) Oct 04, 2012
It seems this has to be explained to you over and over again. Science is not development, nor is it engineering. This is a site that reports (mainly) on science.

Science figures out what works. First you have to find out that you can do such a reaction at all.

The next step is development. Here's where you try to find ways to make the process cheaper and scaleable (in this case e.g. by finding replacements for iridium).

Then comes engineering where you optimize and actually scale the process up for widespread deployment.

Are these distinctions so hard to understand?
SteveL
not rated yet Oct 07, 2012
Widespread catalytic conversion of atmospheric CO2 into useful organic chemicals has been underway for some time. In particular the use of solar energy to facilitate the reaction has been very successful.

The infrastructure for such organic chemical production is readily visible in most countries of the world, they are called plants.

Couldn't resist.
Plants are not technically "catalytic". Sorry, couldn't resist.
SteveL
not rated yet Oct 07, 2012
But no one will invest in plants because everyone knows that money doesn't grow on trees.
People have been investing in plants for thousands of years.

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