A computational method to quantify the adsorption of gas by porous zeolites should help labs know what to expect before they embark upon slow, costly experiments, according to researchers at Rice University.
The new method created by engineers in Rice's Multiscale Materials Modeling Lab accurately calculated the ability of two zeolites, small cage-like molecules with enormous surface area, to trap and store gas molecules.
Among other possibilities, the work could help in the race to meet Department of Energy (DOE) standards that call for the creation by 2015 of materials that can hold 5.5 percent of their weight in hydrogen to fuel vehicles.
"We think we can get there," said Rice materials scientist Rouzbeh Shahsavari, who calculated capacities for two of what he called "remarkably large and colossal cages" and found that one comes close to the mark.
The study by Shahsavari, graduate student Navid Sakhavand and former Rice postdoctoral researcher Prakash Muthuramalingam, now a postdoctoral researcher at Universit Paris-Est, appears online in the American Chemical Society's Journal of Physical Chemistry.
The lab analyzed a dizzying array of potential interactions for two synthetic microporous materials known as zeolitic imidazolate frameworks, ZIF-95 and ZIF-100. Those "colossal cages" may be only nanometers wide, but the molecules they can store that the lab looked at -- hydrogen, methane and nitrogen are much smaller. The zeolites' enormous surface area inside and out gives gas molecules plenty of room to bind.
Aside from storing hydrogen for fuel, ZIFs show potential for size-selective catalysis, environmental remediation and for use as molecular sieves. "Imagine people are designing fit-for-purpose ZIFs," Sakhavand said. "Before jumping into the experiment and synthesizing them, we can help them rapidly screen the gas uptake for each particular ZIF at various temperatures and pressures."
|Contact: David Ruth|