New catalyst converts carbon dioxide to fuel

Jul 30, 2014

Scientists from the University of Illinois at Chicago have synthesized a catalyst that improves their system for converting waste carbon dioxide into syngas, a precursor of gasoline and other energy-rich products, bringing the process closer to commercial viability.

Amin Salehi-Khojin, UIC professor of mechanical and industrial engineering, and his coworkers developed a unique two-step catalytic process that uses and an ionic liquid to "reduce," or transfer electrons, to in a chemical reaction. The new improves efficiency and lowers cost by replacing expensive metals like gold or silver in the reduction reaction.

The study was published in the journal Nature Communications on July 30.

The discovery is a big step toward industrialization, said Mohammad Asadi, UIC graduate student and co-first author on the paper.

"With this catalyst, we can directly reduce carbon dioxide to syngas without the need for a secondary, expensive gasification process," he said. In other chemical-reduction systems, the only reaction product is carbon monoxide. The new catalyst produces syngas, a mixture of carbon monoxide plus hydrogen.

The high density of loosely bound, energetic d-electrons in molybdenum disulfide facilitates charge transfer, driving the reduction of the carbon dioxide, said Salehi-Khojin, principal investigator on the study.

"This is a very generous material," he said. "We are able to produce a very stable reaction that can go on for hours."

"In comparison with other two-dimensional materials like graphene, there is no need to play with the chemistry of molybdenum disulfide, or insert any host materials to get catalytic activity," said Bijandra Kumar, UIC post-doctoral fellow and co-first author of the paper.

"In noble metal catalysts like silver and gold, catalytic activity is determined by the crystal structure of the metal, but with molybdeneum disulfide, the catalytic activity is on the edges," said graduate student Amirhossein Behranginia, a coauthor on the paper. "Fine-tuning of the edge structures is relatively simple. We can easily grow the molybdenum disulfide with the edges vertically aligned to offer better catalytic performance."

The proportion of to hydrogen in the syngas produced in the reaction can also be easily manipulated using the new catalyst, said Salehi-Khojin.

"Our whole purpose is to move from laboratory experiments to real-world applications," he said. "This is a real breakthrough that can take a waste gas—carbon dioxide—and use inexpensive catalysts to produce another source of energy at large-scale, while making a healthier environment."

Explore further: Process holds promise for production of synthetic gasoline

More information: Nature Communications 30 Jul 2014 DOI: 10.1038/ncomms5470

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italba
1.5 / 5 (2) Jul 30, 2014
Whatever catalyst you use, carbon dioxide CANNOT be split into carbon monoxide and hydrogen (syngas) because THERE IS NO HYDROGEN IN IT!!! This is supposed to be a scientific site, please check your articles for a minimum of scientific correctness.
Pexeso
1 / 5 (4) Jul 30, 2014
We cannot convert the carbon dioxide into syngas or whatever else energetically richer mixture without adding of energy, i.e. without introduction of exactly the reason, for which the carbon dioxide gets produced. No catalyst can reverse the energy flux, it can only accelerate it.
Scottingham
4.8 / 5 (6) Jul 30, 2014
I'm pretty sure this is done in the context of another material, probably water. Plenty of hydrogen there!

From the abstract : We uncover that ​molybdenum disulphide shows superior ​carbon dioxide reduction performance compared with the noble metals with a high current density and low overpotential (54 mV) in an ionic liquid.

Ionic liquid = Water with junk in it.
italba
1 / 5 (3) Jul 30, 2014
@Scottingham: So they'll only have to correct the title...
Scottingham
5 / 5 (5) Jul 30, 2014
The catalyst does the conversion, but not on its own. That's not what a catalyst is. It's a facilitator. It speeds up the reaction without being consumed itself.

@ pexeso .. it doesn't reverse the energy flux, but reduces the requirement. Yes energy is still required, but now it's a lot less!
Arties
2 / 5 (4) Jul 30, 2014
Ionic liquid = Water with junk in it.
Nope, ionic liquid = organic salt: 1-Ethyl-3-methylimidazolium tetrafluoroborate which remains molten at room temperature. They used it in water solution, though, because this salt is already used as an corrosion inhibitor for CO2 capture applications. They electrochemically reduced carbon dioxide to carbon monoxide with silver and MoS2 suspensions in diluted water solution of said organic salt. The hydrogen is useful byproduct of reaction here (the electric current, which is not consumed in reduction of CO2 is utilized for reduction of water to hydrogen).

Whole this process is expensive as hell and it would only give a meaning, if we would need a syngas desperately and if we would have some very cheap source of electricity (and carbon dioxide, of course). Under contemporary situation, when we generate the electricity mostly from fossil fuels, then it's indeed much simpler to produce syngas from coil and water directly.
Dr_toad
Jul 30, 2014
This comment has been removed by a moderator.
Arties
2 / 5 (3) Jul 30, 2014
Maybe the 1-Ethyl-3-methylimidazolium tetrafluoroborate salt is used, because it has a large molecules, which adhere to molybdenum disulphide monolayers, penetrate into/between them and helps them to separate at the boundaries of MoS2 flakes. From the same reason the iodine is used in combination with graphite - the resulting material may serve as a powerful catalyst as well. The molybdenum disulphide has a planar structure, which is very similar to graphite.
Dr_toad
Jul 30, 2014
This comment has been removed by a moderator.
FainAvis
not rated yet Jul 31, 2014
The link below describes a process whereby a (depleted) uranium complex can facilitate bringing two carbon dioxide molecules together to form oxalate. This molecule has a carbon-carbon bond. Apparently that is pretty tricky to do. Then they propose to substitute hydrogen for the oxygen to create a hydrocarbon. Yes, that is the reverse of burning, so there has to be an energy input.
Half the story is free to view, the rest is behind a paywall. Hey, I am not a chemist, but it all looks good to me.

http://www.rsc.or...eedstock