Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

Home > Press > Calculations reveal shortcut to characterize zeolites: Rice University method gives accurate picture of gas storage by microscopic cages

A rendering of ZIF-100, a synthetic zeolite, reveals plenty of surface area to which gas molecules (in gold) can bind. A new computer model by Rice University engineers accurately calculates binding forces between gases and zeolites to reveal the material’s maximum uptake capacity in a variety of conditions. Credit: Navid Sakhavand/Rice University
A rendering of ZIF-100, a synthetic zeolite, reveals plenty of surface area to which gas molecules (in gold) can bind. A new computer model by Rice University engineers accurately calculates binding forces between gases and zeolites to reveal the material’s maximum uptake capacity in a variety of conditions.

Credit: Navid Sakhavand/Rice University

Abstract:
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.

Calculations reveal shortcut to characterize zeolites: Rice University method gives accurate picture of gas storage by microscopic cages

Houston, TX | Posted on November 12th, 2013

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 Université 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."

The researchers' primary goal was to prove the accuracy of their method when compared with a host of experimental results on hydrogen storage carried out elsewhere. Shahsavari said the researchers modeled the interactions between molecules of the three gases with each other and with the binding ligands in the zeolites at 77 and 300 kelvins (-321 and 80 degrees Fahrenheit, respectively) and at various pressures.

For hydrogen, they determined that both zeolites stored about three times as much gas at 77 K and at 100-bar pressure (100 times that of the atmosphere at sea level) than they would at room temperature. ZIF-100, in particular, adsorbed 3.4 percent of its weight in hydrogen, which approaches the DOE standard, Shahsavari said.

"We didn't reach that DOE target with this design, but if we can functionalize the ZIFs by adding ligand-binding moieties (the functional groups in a molecule) into the pore space, then we might be able to. We're working on that," he said.

They were also able to calculate both subtle and significant differences between the adsorptive qualities based on various input parameters of gas, pressure, temperature and type of zeolite. For example, they came to the counterintuitive conclusion that ZIF-100, the larger of the two zeolites, could adsorb more small-molecule hydrogen but fewer of the larger methane molecules than ZIF-95 under similar conditions.

"So our method not only accurately predicts the properties of these porous materials, but also provides fundamental insights that can be leveraged to further improve their properties," Shahsavari said.

The Rice lab's method involved several steps. First, the team performed first-principle calculations to describe the very weak atomic interactions - the van der Waals-related London dispersion forces — among each of the three types of gas molecules and the two ZIFs. The next step used those results to align the potentials among various atomic pairs. Those were plugged into large-scale Monte Carlo simulations to predict how much of each gas each porous zeolite could adsorb.

"Because we combined two methods, each appropriate for a different length scale, we were able to predict the maximum capacity of these materials with high accuracy while maintaining reasonable computational time," Shahsavari said.

The method may seem simple, but calculating integrative forces between thousands of gas molecules and each ZIF was not. It took the combined power of Rice's DAVinCI and SUGAR supercomputers to find results for all the variations. Even so, calculations for a single data point - one molecule, one zeolite, one temperature - often took 96 processing cores three days to complete.

Shahsavari said the method should also be good for analyzing the potential for zeolites as membranes to separate gases. "It can work not only for single molecules, but also gas mixtures," he said. "This provides a good computational framework so one can do rapid screening for the desired properties."

Rice University, the National Institutes of Health, the National Science Foundation and an IBM Shared University Research Award in partnership with CISCO, Qlogic and Adaptive Computing supported the research. The Data Analysis and Visualization Cyber Infrastructure (DAVinCI) and Shared University Grid at Rice (SUGAR) supercomputers are administered by Rice's Ken Kennedy Institute for Information Technology.

####

About Rice University
Located on a 300-acre forested campus in Houston, Rice University is consistently ranked among the nation’s top 20 universities by U.S. News & World Report. Rice has highly respected schools of Architecture, Business, Continuing Studies, Engineering, Humanities, Music, Natural Sciences and Social Sciences and is home to the Baker Institute for Public Policy. With 3,708 undergraduates and 2,374 graduate students, Rice’s undergraduate student-to-faculty ratio is 6-to-1. Its residential college system builds close-knit communities and lifelong friendships, just one reason why Rice has been ranked No. 1 for best quality of life multiple times by the Princeton Review and No. 2 for “best value” among private universities by Kiplinger’s Personal Finance. To read “What they’re saying about Rice,” go to tinyurl.com/AboutRiceU.

Follow Rice News and Media Relations via Twitter @RiceUNews

For more information, please click here

Contacts:
David Ruth
713-348-6327


Mike Williams
713-348-6728

Copyright © Rice University

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related Links

Read the abstract at:

Shahsavari Group:

Related News Press

News and information

Remote-control shoots laser at nano-gold to turn on cancer-killing immune cells April 20th, 2018

New qubit now works without breaks: A universal design for superconducting qubits has been created April 19th, 2018

Observing biological nanotransporters: Chemistry April 19th, 2018

Salt boosts creation of 2-D materials: Rice University scientists show how salt lowers reaction temperatures to make novel materials April 18th, 2018

Govt.-Legislation/Regulation/Funding/Policy

Remote-control shoots laser at nano-gold to turn on cancer-killing immune cells April 20th, 2018

Salt boosts creation of 2-D materials: Rice University scientists show how salt lowers reaction temperatures to make novel materials April 18th, 2018

Quantum shift shows itself in coupled light and matter: Rice University scientists corral, quantify subtle movement in condensed matter system April 16th, 2018

When superconductivity disappears in the core of a quantum tube: By replacing the electrons with ultra-cold atoms, a group of physicists has created a perfectly clean material, unveiling new states of matter at the quantum level April 16th, 2018

Discoveries

Remote-control shoots laser at nano-gold to turn on cancer-killing immune cells April 20th, 2018

New qubit now works without breaks: A universal design for superconducting qubits has been created April 19th, 2018

Observing biological nanotransporters: Chemistry April 19th, 2018

Salt boosts creation of 2-D materials: Rice University scientists show how salt lowers reaction temperatures to make novel materials April 18th, 2018

Materials/Metamaterials

Salt boosts creation of 2-D materials: Rice University scientists show how salt lowers reaction temperatures to make novel materials April 18th, 2018

Individual impurity atoms detectable in graphene April 18th, 2018

Psst! A whispering gallery for light boosts solar cells April 14th, 2018

Artificial intelligence accelerates discovery of metallic glass: Machine learning algorithms pinpoint new materials 200 times faster than previously possible April 13th, 2018

Announcements

Remote-control shoots laser at nano-gold to turn on cancer-killing immune cells April 20th, 2018

New qubit now works without breaks: A universal design for superconducting qubits has been created April 19th, 2018

Observing biological nanotransporters: Chemistry April 19th, 2018

Salt boosts creation of 2-D materials: Rice University scientists show how salt lowers reaction temperatures to make novel materials April 18th, 2018

Interviews/Book Reviews/Essays/Reports/Podcasts/Journals/White papers

Remote-control shoots laser at nano-gold to turn on cancer-killing immune cells April 20th, 2018

New qubit now works without breaks: A universal design for superconducting qubits has been created April 19th, 2018

Observing biological nanotransporters: Chemistry April 19th, 2018

Salt boosts creation of 2-D materials: Rice University scientists show how salt lowers reaction temperatures to make novel materials April 18th, 2018

Energy

Psst! A whispering gallery for light boosts solar cells April 14th, 2018

High efficiency solar power conversion allowed by a novel composite material: A composite thin film developed at INRS improves significantly solar cells' power conversion efficiency April 10th, 2018

Light 'relaxes' crystal to boost solar cell efficiency: Rice, Los Alamos discovery advances case for perovskite-based solar cells April 6th, 2018

Double perovskites in environmentally friendly solar cells: Long electron-hole diffusion length in high-quality lead-free double perovskite films April 6th, 2018

Automotive/Transportation

HTA to Present European Strategy for Competitive Micro- and Nanotechnologies & Smart Systems: Special Event in Brussels on April 24 Gathers Research Institutes’ CEOs, European Commissioners and Key European Industrials April 17th, 2018

CAP-XX Develops Industry’s First 3 Volt Thin Prismatic Supercapacitors: Provides peak power support to 3V coin cell batteries and eliminates need for 2.7V LDO regulator for less expensive, smaller, more energy-efficient designs with extended battery life April 11th, 2018

Mapping battery materials with atomic precision: Berkeley Lab researchers map the atoms of battery materials and explored how composition affects structure March 8th, 2018

GLOBALFOUNDRIES Strengthens 22FDX® eMRAM Platform with eVaderis’ Ultra-low Power MCU Reference Design: Co-developed technology solution enables significant power and die size reductions for IoT and wearable products February 27th, 2018

NanoNews-Digest
The latest news from around the world, FREE



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project