The University of Houston Cullen College of Engineering has put up a perfect record in the 2012 CAREER Award grant competition, with all six of its applicants receiving the honor.
Administered by the National Science Foundation (NSF), CAREER Awards are given to outstanding junior-level faculty members to help them launch long-term, successful research careers. They are among the most prestigious grants in the STEM fields (science, technology, engineering and mathematics) and are one of the few awards factored into the official Top American Research University rankings.
The latest winner from the Cullen College is Jeffrey Rimer, assistant professor of chemical and biomolecular engineering. Rimer won a five-year, $400,000 grant to expand his efforts to improve zeolites, a class of catalysts used in the petroleum and chemical industries to create a range of different products, from ion-exchange additives in detergents to gasoline and alternative fuels.
Zeolites are nanoporous materials with small channels that span their entire structure. Molecules enter the channels, react within the zeolite and then exit, transformed into something new.
As a rule of thumb, the shorter these channels, the better, said Rimer. In longer channels, residue from the reactions is more likely to build up in the pores, limiting zeolite efficiency. In addition, shorter channels increase the product yield.
“If a molecule enters the zeolite and reacts, you want the products to exit quickly to improve efficiency,” said Rimer. “If you have a zeolite with really long channels, the molecular flux is very low. An ideal catalyst is a thin crystal with high porous surface area, allowing molecules to enter, react, and then diffuse rapidly.”
So Rimer has developed – and recently won a full patent for – a method to produce ultra-thin zeolites.
During the synthesis of commercial-grade zeolites, the individual crystals grow through the attachment of growth units to the zeolite surface. Rimer has discovered certain molecules that attach to specific zeolite surfaces and block growth units from attaching, thereby tailoring the size and shape of zeolite crystals.
While the modified zeolites retain the same basic shape, through this process they can measure as thick as 100 nanometers, about 10-times thinner than unmodified zeolites.
With his earlier research to validate the approach of using zeolite modifiers, funded by an NSF BRIGE Grant, Rimer worked primarily with commercially available molecules. The CAREER award will allow him to create entirely new molecules to tailor the growth of specific zeolites. In doing so, he aims to develop a rational system for creating such molecules for any targeted zeolite.
“When we understand how a small library of molecules can tailor the shape of any single zeolite, we can think about other modifier-zeolite combinations,” Rimer said. “If you were to take a zeolite that hasn’t been studied by this approach, could you, based on its structure, predict a set of four or five molecules that may be effective in controlling its growth? The goal is to expand our understanding of how this works and establish some guidelines for creating these molecules.”
With this win, Rimer joins five other Cullen College junior faculty members who have received a 2012 CAREER Award: Jiming Bao, Jacinta Conrad, Debora Rodrigues, Wei-Chuan Shih and Gila Stein. According to Joseph W. Tedesco, Elizabeth D. Rockwell Dean, such a strong showing in the CAREER competition is proof of the advances the college has made in recent years.
“The Cullen College’s faculty ranks have grown by more than 20 percent since 2007,” he said. “These CAREER Awards prove that we’ve brought in some truly outstanding young researchers who will help take our research program to new heights. We are proud of them all!”