The Acid Test

<p>Acid Test, Materials, Horizons May 2015</p>

Acid Test, Materials, Horizons May 2015

Earth’s air pollution and climate change issues are linked to combustion and its detrimental byproducts: greenhouse gases such as carbon dioxide (CO2) and gases that pollute the atmosphere such as nitrogen oxides.

The good news is that today’s advanced materials can trap or neutralize these acid gases right in the smokestack, or even capture CO2 straight from the atmosphere. Multiple research teams are working to increase the efficiency of these important materials; the Department of Energy (DOE) is currently funding a number of such projects under its Energy Frontier Research Center (EFRC) program.

But a key question remains: How do acidic gases affect materials designed to lower their emissions? How durable, for instance, will these advanced materials be when subjected to real-world environments like the hot exhaust flues of a power plant?

“There’s a knowledge gap here — scientists don’t yet understand the fundamentals of how acid gases like carbon dioxide, nitrogen oxides, and sulfur oxides interact with important classes of materials,” said Krista Walton, an associate professor in the Georgia Tech School of Chemical & Biomolecular Engineering (ChBE). “If you create a new material that separates CO2 with record efficiency in the lab, but it only lasts a few days in an industrial environment, then it’s not a useful advance.”

The DOE recently awarded a four-year $11.2 million grant to Georgia Tech to lead an EFRC that studies materials degradation caused by acid gases. Directed by Walton, the new center involves research teams from six universities and a government laboratory. Collaborating with Georgia Tech are researchers from Lehigh University, University of Alabama, University of Florida, University of Wisconsin, Washington University in St. Louis, and Oak Ridge National Laboratory.

Dubbed the Center for Understanding and Control of Acid Gas-Induced Evolution of Materials for Energy (UNCAGE-ME), the Georgia Tech-led effort is one of 10 new EFRCs recently funded by the DOE.


The seven partners are investigating a range of solid materials — including metals, polymers, ceramics, and composites — that have the ability to trap or chemically alter acid gases via separations/ catalysis techniques. The overall study is divided into several research thrust areas, and the goal in each case is to understand, down to the molecular level, exactly what’s taking place as acid gases interact with a given material.

The EFRC is multifaceted, Walton explained. Unlike many materials efforts that focus on designing a single material for a target application, this center covers numerous materials and employs a wide range of research techniques. Moreover, the research process itself is highly integrated — most of the principal investigators from the seven partner institutions are involved in two or more projects.

The center is tackling four major research thrusts, all concerned with materials relevant to industry. The work focuses on acid-gas interactions with:

  • Model nonporous oxide-based solids, such as copper and titanium oxides.
  • Ordered (crystalline) porous materials, such as metal organic frameworks.
  • Disordered porous materials, including carbons and amine/oxide composites.
  • External surfaces of porous materials.

“The multiple partner structure of this EFRC fits our culture at Georgia Tech very well, because we’re accustomed to collaborating,” said David Sholl, a ChBE professor who is an EFRC deputy director and leader of the thrust investigating external surfaces of porous materials. “It means we can do things that no individual person can do alone; typically three, four, or even five different research groups are contributing their techniques to each thrust.”

Professor Christopher W. Jones of ChBE is leading the thrust on disordered porous materials, while Professor Sankar Nairof ChBE is leading the ordered porous materials thrust. Assistant Professors Michael Filler and Ryan Lively of ChBE, as well as Professor Thomas Orlando of the Georgia Tech School of Chemistry and Biochemistry, are also principal investigators in the center. Zili Wu of the Oak Ridge National Laboratory is leading the research thrust that is addressing model nonporous oxide-based solids.

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