Volume 92 Issue 45 | p. 29 | Concentrates
Issue Date: November 10, 2014

Additional Advances In CO2 Fixation

Two research groups report new catalysts that use carbon dioxide as a starting material to make cyclic carbonates
Department: Science & Technology
News Channels: Materials SCENE, Environmental SCENE, JACS In C&EN
Keywords: metal-organic framework, carbon dioxide, carbonate, organocatalyst, silanediol

When it comes to trapping carbon dioxide to reduce industrial greenhouse gas emissions, the biggest challenge is finding something to do with the CO2. One chemical approach is to insert CO2 into epoxides to form cyclic carbonates, which in turn can be used as solvents, as battery electrolytes, and to make polycarbonate plastics. However, the reaction usually requires high temperature and pressure. A team led by Omar K. Farha and Joseph T. Hupp of Northwestern University has developed a hafnium-based metal-organic framework (MOF) catalyst for the process that works under ambient conditions (J. Am. Chem. Soc. 2014, DOI: 10.1021/ja508626n). The researchers found that hafnium forms stronger metal-oxygen bonds in MOFs compared with other metals and thus is a stronger Brønsted acid and an optimal catalyst. In a separate development, Anita E. Mattson’s group at Ohio State University reports using silanediols to catalyze CO2 insertion into epoxides under ambient conditions (ChemSusChem 2014, DOI: 10.1002/cssc.201402783). Silanediols are noncovalent organocatalysts codiscovered by Mattson’s group that mediate a range of chemical reactions by coupling reaction partners through hydrogen-bonding interactions.

Credit: J. Am. Chem. Soc.
A hafnium-based metal-organic framework catalyzes reactions with epoxides.
Credit: J. Am. Chem. Soc.
Chemical & Engineering News
ISSN 0009-2347
Copyright © American Chemical Society
Xiaojin (Mon Nov 17 17:20:16 EST 2014)
Comment from a MOF researcher: Undoubtedly, this is very interesting work in terms of CO2 chemical fixation under ambient conditions catalyzed by MOF catalysts. As far as I know, in the MOF area there were two publications came out at the very early of this year from another group, investigating the same topic of CO2 fixation coupled with epoxides under ambient conditions. (Chem. Commun., 2014, 50, 5316-5318; Angew Chem. Int. Ed., 2014, 53, 2615-2619) I am just curious how this work got the attention from editor office, instead of the two earlier work.
I would really appreciate it if you could address the question.
worldperfectscience (Mon Aug 10 06:32:31 EDT 2015)
It´s life man! It´s not supposed to be fair;)
Steve Ritter (Wed Nov 26 10:54:38 EST 2014)
Thanks for your comment Xiaojin, you raise a good question. Many researchers are developing MOFs for a range of applications, including CO2 fixation, such as the two nice papers you mention by Shengqian Ma and coworkers at the University of South Florida. That C&EN did not write about these two papers does not mean they escaped our attention--C&EN covers as much interesting new chemistry as possible, but we can't come close to covering it all. The two papers covered in this science concentrate were selected because they bring a couple of unique aspects to MOFs and/or CO2 fixation. In the one case, the new MOF includes hafnium that is not typically used in MOFs. But as many chemists are discovering, hafnium is a versatile catalyst--it is capable not only of marrying epoxides and CO2 but also epoxides with other small molecules. The copper-based MOFs reported by Ma's group might also do that, but it was not included in the papers. In the second case, silanediols represent a metal-free option for CO2 fixation. Please continue to ask questions and point out research you think we have missed.

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