Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

Home > Press > Membrane Breaks Through Performance Barrier: Rapid, low-energy process creates crystalline films free of debilitating defects

Shown in the image are depictions of (top) a conventionally calcined c-oriented silicalite-1 zeolite membrane and (bottom) an identically oriented membrane that has undergone rapid thermal processing (RTP). Red and green regions in the 3D schematics are indicative of zeolite crystal grains and defects/grain boundaries, respectively. A scanning electron microscopy (SEM) image of the membrane cross-section is shown, as well as representative cross-sectional images collected of dye-saturated membranes via laser scanning confocal microscopy. The schematics and representative data highlight the accessibility and inaccessibility of grain boundaries, respectively, in the conventionally calcined and RTP treated membranes.

Credit: Jungkyu Choi, University of California, Berkeley; Mark A. Snyder, Lehigh University; and Michael Tsapatsis, Univerity of Minnesota
Shown in the image are depictions of (top) a conventionally calcined c-oriented silicalite-1 zeolite membrane and (bottom) an identically oriented membrane that has undergone rapid thermal processing (RTP). Red and green regions in the 3D schematics are indicative of zeolite crystal grains and defects/grain boundaries, respectively. A scanning electron microscopy (SEM) image of the membrane cross-section is shown, as well as representative cross-sectional images collected of dye-saturated membranes via laser scanning confocal microscopy. The schematics and representative data highlight the accessibility and inaccessibility of grain boundaries, respectively, in the conventionally calcined and RTP treated membranes.

Credit: Jungkyu Choi, University of California, Berkeley; Mark A. Snyder, Lehigh University; and Michael Tsapatsis, Univerity of Minnesota

Abstract:
Engineers have developed a new method for creating high-performance membranes from crystal sieves called zeolites; the method could increase the energy efficiency of chemical separations up to 50 times over conventional methods and enable higher production rates.

Membrane Breaks Through Performance Barrier: Rapid, low-energy process creates crystalline films free of debilitating defects

Arlington, VA | Posted on July 31st, 2009

The ability to separate and purify specific molecules in a chemical mixture is essential to chemical manufacturing. Many industrial separations rely on distillation, a process that is easy to design and implement but consumes a lot of energy.

Researchers led by chemical engineer Michael Tsapatsis of the University of Minnesota reported this discovery in the July 31, 2009, issue of Science.

Tsapatsis's team developed a rapid heating treatment to remove structural defects in zeolite membranes that limit their performance, a problem that has plagued the technology for decades.

"Using membranes rather than energy-intensive processes such as distillation and crystallization could have a major impact on industry," said NSF program officer Rosemarie Wesson. This discovery could increase the energy efficiency of producing important chemical solvents such as xylene and renewable biofuels such as ethanol and butanol.

Creating Zeolite Membranes

Researchers create zeolite membranes by growing a film of crystals with small organic ions added to direct the crystal structure and pore size--two zeolite properties that help determine which molecules can pass through the material. Then they slowly heat the zeolite film in a process called calcination to decompose the ions and open the pores.

However, Tsapatsis explained, "This method for creating zeolite films often leaves cracks at the boundaries between grains of zeolite crystals." These defects have prevented zeolite films from being used effectively as membranes, because molecules of unwelcome chemicals that are rejected by the zeolite pores can still penetrate through the membrane defects.

"While it may be possible to correct some of these defects, the repair process is difficult and expensive," Wesson said. Currently zeolite membranes have found use only in specialized, smaller-scale applications, such as the removal of water from alcohols or other solvents.

In an effort to minimize the formation of cracks and other defects, the heating rate during calcination is very gentle, and the process can take as long as 40 hours--typically a material is heated at a rate of 1 degree Celsius per minute up to a temperature between 400 and 500 degrees Celsius, where it is held steadily for several hours before being allowed to slowly cool. Because conventional calcination is time-consuming and energy-intensive, it has been difficult and expensive to produce zeolite membranes on a large scale.

Hotter and Faster

Tsapatsis's team developed a treatment called Rapid Thermal Processing (RTP), a treatment in which zeolite film is heated to 700 degrees Celsius within one minute and kept at that temperature for no more than two minutes. Acting as an annealing method, RTP refines the granular structure of the zeolite crystal film.

When the researchers examined the RTP-treated films, they found no evidence of cracks at grain boundaries. Although they found other types of defects, these don't seem to affect the membrane properties or performance.

In a comparison to conventionally-made zeolite membranes, Tsapatsis said, "We observed a dramatic improvement in the separation performance of the RTP-treated membranes." A second round of RTP treatment improved separation performance even further, to a level on par with current industry separation methods.

Tsapatsis involved several graduate students in this project: Jungkyu Choi, now a postdoctoral fellow at the University of California, Berkeley, performed most of the experiments; Hae-Kwon Jeong, now an assistant professor at Texas A&M University, performed some early RTP treatments while a postdoctoral fellow at the University of Illinois at Urbana-Champaign with engineering professor Richard Masel; and Jared Stoeger, currently a doctorate candidate with Tsapatsis, performed permeation measurements using stainless steel tube supported membranes. Mark Snyder, now an assistant professor at Lehigh University, performed confocal microscopy experiments while a postdoctoral fellow in Tsapatsis's group.

The researchers demonstrated the RTP process on relatively thick (several micrometers) zeolite membranes. Tsapatsis and collaborators are now working towards making zeolite membranes 10 to 100 times thinner to allow molecules to pass through more quickly. They hope to eventually implement RTP treatment with its beneficial effects to these membranes as well.

####

About National Science Foundation
The National Science Foundation (NSF) is an independent federal agency that supports fundamental research and education across all fields of science and engineering. In fiscal year (FY) 2009, its budget is $9.5 billion, which includes $3.0 billion provided through the American Recovery and Reinvestment Act. NSF funds reach all 50 states through grants to over 1,900 universities and institutions. Each year, NSF receives about 44,400 competitive requests for funding, and makes over 11,500 new funding awards. NSF also awards over $400 million in professional and service contracts yearly.

For more information, please click here

Contacts:
Media Contacts
Cecile Gonzalez
NSF
(703) 292-8538


Joshua A. Chamot
NSF
(703) 292-7730


Ryan Mathre
University of Minnesota News Service
(612) 625-0552


Rhonda Zurn
University of Minnesota Institute of Technology
(612) 626-7959


Program Contacts
Rosemarie D. Wesson
NSF
(703) 292-7070


Principal Investigators
Michael Tsapatsis
University of Minnesota
(612) 626-0920

Copyright © National Science Foundation

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

Michael Tsapatsis homepage

Related zeolite research

Related News Press

News and information

Bringing the atomic world into full color: Researchers turn atomic force microscope measurements into color images October 19th, 2017

'Find the Lady' in the quantum world: International team of researchers presents method for quantum-mechanical swapping of positions October 18th, 2017

Long nanotubes make strong fibers: Rice University researchers advance characterization, purification of nanotube wires and films October 17th, 2017

Spinning strands hint at folding dynamics: Rice University lab uses magnetic beads to model microscopic proteins, polymers October 17th, 2017

Chemistry

What can be discovered at the junction of physics and chemistry October 6th, 2017

Copper catalyst yields high efficiency CO2-to-fuels conversion: Berkeley Lab scientists discover critical role of nanoparticle transformation September 20th, 2017

Chemical hot spots: Scanning tunneling microscopy measurements identify active sites on catalyst surfaces September 7th, 2017

More durable, less expensive fuel cells: University of Delaware researchers have developed a new technology that could speed up the commercialization of fuel cell vehicles September 5th, 2017

Discoveries

Bringing the atomic world into full color: Researchers turn atomic force microscope measurements into color images October 19th, 2017

'Find the Lady' in the quantum world: International team of researchers presents method for quantum-mechanical swapping of positions October 18th, 2017

Long nanotubes make strong fibers: Rice University researchers advance characterization, purification of nanotube wires and films October 17th, 2017

Spinning strands hint at folding dynamics: Rice University lab uses magnetic beads to model microscopic proteins, polymers October 17th, 2017

Materials/Metamaterials

Long nanotubes make strong fibers: Rice University researchers advance characterization, purification of nanotube wires and films October 17th, 2017

Injecting electrons jolts 2-D structure into new atomic pattern: Berkeley Lab study is first to show potential of energy-efficient next-gen electronic memory October 13th, 2017

The secret to improving liquid crystal's mechanical performance: Better lubricating properties of lamellar liquid crystals could stem from changing the mobility of their structural dislocations by adding nanoparticles October 13th, 2017

Rice U. lab surprised by ultraflat magnets: Researchers create atom-thick alloys with unanticipated magnetic properties October 13th, 2017

Announcements

Bringing the atomic world into full color: Researchers turn atomic force microscope measurements into color images October 19th, 2017

Long nanotubes make strong fibers: Rice University researchers advance characterization, purification of nanotube wires and films October 17th, 2017

Spinning strands hint at folding dynamics: Rice University lab uses magnetic beads to model microscopic proteins, polymers October 17th, 2017

Rice U. study: Vibrating nanoparticles interact: Placing nanodisks in groups can change their vibrational frequencies October 16th, 2017

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



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project