ADVERTISEMENT
2 /3 FREE ARTICLES LEFT THIS MONTH Remaining
Chemistry matters. Join us to get the news you need.

If you have an ACS member number, please enter it here so we can link this account to your membership. (optional)

ACS values your privacy. By submitting your information, you are gaining access to C&EN and subscribing to our weekly newsletter. We use the information you provide to make your reading experience better, and we will never sell your data to third party members.

ENJOY UNLIMITED ACCES TO C&EN

Pollution

Improved version of oxygen-storage material boosts engine-emission cleanup

Simple catalyst treatment could lead to better catalytic converters

by Mitch Jacoby
September 19, 2020 | APPEARED IN VOLUME 98, ISSUE 36

 

A simple heat treatment can alter the structure and thermal stability of a cerium-zirconium material, thereby improving its ability to strip pollutants from automobile engine emissions (Appl. Catal., B 2020, DOI: 10.1016/j.apcatb.2020.119450). Catalytic converters on gasoline-powered vehicles scrub toxic combustion products in the exhaust stream with three-way catalysts (TWCs). The name reflects the catalysts’ ability to oxidize carbon monoxide and hydrocarbons and reduce smog-forming nitrogen oxides. The key to TWCs’ knack for mediating oxidations and reductions—chemically opposed reactions—is a rhodium-doped cerium oxide–zirconium oxide (CZO) oxygen-storage material. CZO intermittently stores oxygen during reduction steps and releases it during oxidations. Today’s TWCs use the tetragonal form, t-CZO. Recent studies suggest that the pyrochlore form, pyr-CZO, which has a different lattice structure, could outperform t-CZO. But pyr-CZO morphs into t-CZO at high temperatures, and it has low surface area, rendering it ineffective catalytically. A research team including Jason Wu of Ford Motor and Joerg R. Jinschek of the Ohio State University has shown that treating commercial CZO with hydrogen at 1,200 °C followed by a simple cooling procedure leads to high-surface-area pyr-CZO, which retains its structure after aging at 910 °C. And it outperforms t-CZO in converting nitric oxide and hydrocarbons.

X

Article:

This article has been sent to the following recipient:

Leave A Comment

*Required to comment