By Emil Venere
New Catalyst Design Will Aim to Reduce Nitrogen Oxides in Diesel Exhaust
Assistant Professor Raj Gounder has received a Faculty
Early Career Development (CAREER) Award from the
National Science Foundation for a project focusing
on a catalyst designed to reduce tailpipe emissions
for diesel exhaust. The catalyst technology also might
be applied to refineries in the production of fuels and
chemicals from petroleum and biomass.
New catalyst designs are needed because current
technologies do not function well at cold temperatures.
“When vehicles first start, the catalyst is cold and most
of the emissions occur during this time,” Gounder said.
“Between 80-to-90 percent of the current emissions
that make it through the tailpipe unconverted now
happen under what’s called cold-start conditions.”
Fixing the problem has become a national research
priority because more stringent emission standards
in coming years will require improved pollution-control systems.
“Today’s materials won’t be able to meet the
new emissions target,” he said. “We are trying to
reformulate the catalyst so it can work over a wider
His CAREER project involves a type of catalyst called
zeolites, workhorses in petroleum and chemical
refineries and also for systems that reduce diesel-
exhaust emission of smog-causing nitrogen oxides.
The zeolites have a crystalline structure containing
pores about 1 nanometer in diameter, providing
“active sites” where the chemistry takes place. The
crystalline framework can be “doped” with aluminum
atoms that take root in the structure. Some of the
aluminum atoms are paired, and these negatively
charged pairs attract positively charged copper ions
critical to a chemical reaction that reduces emissions
of nitrogen oxides.
“The copper ions are anchored to the aluminum
pairs, and nitrogen oxides bond to these copper ions,”
However, although the arrangement of the paired
aluminum atoms in the crystal’s framework is critical
Assistant Professor Raj Gounder with his research group.