Supporting Cleaner Engine Emissions - C&EN Global Enterprise (ACS

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NEWS OF THE WEEK

SUPPORTING CLEANER ENGINE EMISSIONS

SUPPORTIVE In excess oxygen, rhodium nanoparticles supported on ZrP2O7 (blue spheres and polyhedrons) can convert hydrocarbons in exhaust to aldehydes that strip oxygen from NOx.

PACIFICHEM NEWS: Phosphates

help rhodium catalysts strip NOx from vehicle exhaust

COURTESY OF PHILIP HERAUD

wands, they probably would wave them to simultaneously increase a car’s fuel efficiency and reduce its engine emissions. That would be a welcome trick because improving one often comes at the expense of the other. No one was handing out magic wands at the 7th International Chemical Congress of Pacific Basin Societies, or Pacifichem, in Honolulu. But last week at a symposium focusing on automobile emissions cleanup, Haris Puspito Buwono, a graduate student working with Masato Machida of Kumamoto University, described a catalytic “magic trick” that could help carmakers sidestep the trade-off between fuel efficiency and emissions. Burning gasoline in excess oxygen can boost fuel efficiency compared with burning stoichiometric mixtures of oxygen and fuel. But in the excessoxygen condition, which is known as lean-burn

INFRARED SPECTRA TAKEN ON SHIP PACIFICHEM NEWS: Measurements give snapshot of ocean organisms’ photosynthetic activity

P Heraud poses with a device used for measuring ocean conductivity, temperature, and density that could be used for obtaining phytoplankton samples.

HYTOPLANKTON play an important role in

the ocean, and even global, ecosystem. The tiny photosynthesizing organisms are a major nutrient source in the marine food web, and because they sequester in their shells billions of tons of carbon dioxide from the atmosphere, they’re an important factor in climate models. But researchers haven’t had a good way to measure in real time the organisms’ contributions to the marine ecosystem. Last week in Honolulu, at the 7th International Chemical Congress of Pacific Basin Societies, or Pacifichem, Australian researchers presented a model they developed that predicts phytoplankton composition and photosynthesis productivity from infrared spectroscopy measurements. Philip Heraud of Monash University and coworkers tested their model by taking shipboard IR measurements of phytoplankton during the maiden voyage of the Australian research vessel Investigator in March. To CEN.ACS.ORG

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ACS CATAL.

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F AUTOMOBILE MANUFACTURERS had magic

because the air-to-fuel ratio is lean in fuel, today’s catalytic converters struggle to scrub nitrogen oxides (NOx) from the exhaust. So automakers design gasoline engines to operate near stoichiometry to reduce emissions of NOx, which are involved in reactions that produce ozone and smog in the atmosphere. Buwono reported that rhodium nanoparticles, the main catalytically active material in modern catalytic converters, can do a better job tackling NOx under lean conditions if the catalyst support is tailored for the job. Working with Yuki Nagao, a catalyst specialist with Mitsui Mining & Smelting, and others, Buwono, Machida, and coworkers prepared rhodium catalysts supported on a series of phosphates, including ZrP2O7, LaPO4, AlPO4, and YPO4. As the air-to-fuel ratio increased above stoichiometry, all of the phosphate-supported catalysts did a better job of scrubbing NOx from simulated exhaust mixtures than Rh/ZrO2, the conventional catalyst. Rh/ZrP2O7 worked best (ACS Catal. 2015, DOI: 10.1021/cs5020157). Seoul National University’s Do Heui Kim, an emissions catalysis specialist, points out that in addition to studying catalysts in powdered form, the researchers also anchored them on the same type of porous, ceramic, honeycomb-like brick found in automobiles everywhere. Testing the catalysts under these real-world conditions makes it much easier to translate the results to practical applications, he says.—MITCH JACOBY

Heraud’s knowledge, that voyage—which traversed the Southern Ocean encircling Antarctica—marks the first time such measurements have been made on a ship. Heraud’s team developed its model from earlier lab studies of phytoplankton with fast, easy IR measurements (ISME J. 2015, DOI: 10.1038/ismej.2015.123). The IR spectra provide a comprehensive picture of the phytoplankton’s biochemical makeup and, thus, its photosynthetic productivity. To make the shipboard measurements, Heraud’s team pumped water onto the ship and passed it through sequential filters to divide the phytoplankton into different size fractions, which the researchers analyzed by attenuated total reflectance Fourier transform IR spectroscopy. Their model predicted the organisms’ photosynthetic rate within 5% of the measured value. “The new work gives data virtually in real time, which represents a technological innovation and a significant step forward for marine biology,” Leanne Armand, a diatom expert at Macquarie University and chief scientist on the Investigator, told C&EN. Armand has previously collaborated with Heraud but was not directly involved with the shipboard measurements. “In the past, the best we could do was preserve samples and send them back to the lab for some bulk, generalized analysis months later.” “We envisage that we can get real-time information about the state of phytoplankton communities within minutes, rather than having data that are months old,” Heraud said.—CELIA ARNAUD

DECEMBER 21, 2015