Featured Research

from universities, journals, and other organizations

Thin-skinned catalyst for chemical reactions: Yolk-shell nanocrystal structure offers greater selectivity for heterogeneous catalysis

Date:
December 13, 2012
Source:
Boston College
Summary:
A team of researchers reports developing a nanocrystal structure capable of controlling catalysis with the pores of a skin-like membrane that can accept or reject molecules based on their size or chemical properties.

Boston College researches started with a metallic crystal. It was then coated with a "sacrificial layer" of copper oxide. The application of ZIF-8 formed a porous skin that then etched away the copper. Within the resulting cavity, researchers were able to control the chemical reaction thanks to the skin-like shell of ZIF-8.
Credit: Journal of the American Chemical Society

A chemical nanostructure developed by Boston College researchers behaves much like the pores of the skin, serving as a precise control for a typically stubborn method of catalysis that is the workhorse of industrial chemistry.

Related Articles


Scientists have been trying to develop so-called yolk-shell catalysts as a means of imparting greater selectivity on heterogeneous catalysis, a process used in most industrial chemistry, including the manufacture of fine chemicals, petrochemicals and agrochemicals.

Boston College Assistant Professor of Chemistry Chia-Kuang Tsung and his team developed a nanostructure that can regulate chemical reactions thanks to a thin, porous skin capable of precisely filtering molecules based on their size or chemical make-up, the group reported recently in the Journal of the American Chemical Society.

"The idea is to make a smarter catalyst," said Tsung. "To do that, we placed a layer of 'skin' on the surface that can discriminate between which chemical reacts or does not react with the catalyst."

The team started with a nanoscale metallic crystal, then applied a "sacrificial layer" of copper oxide over it, Tsung said. Next, a shell of highly refined material known as a metal-organic framework, or MOF, was applied to the structure. Immediately, the polycrystalline MOF adhered to the cooper oxide, forming and outer layer of porous "skin." At the same time, the MOF began to etch away the copper oxide layer from the surface of the crystal, creating a tiny chamber between the skin and the catalyst where the chemical reaction can take place.

Testing the structure with gases of varying molecular structure, Tsung said the skin proved it could allow ethylene, with the small molecule size, to pass through and reach the catalyst. The gas cyclooctene, with larger molecule size, was effectively blocked from reaching the catalyst. Tests showed the central difference between new method and earlier incarnations of yolk-shell catalysts was the creation of the empty chamber between the skin and catalyst, the researchers reported.

Tsung said the unprecedented level of control is a significant step in the use of unique nanoscale chemical structures in the effort to impart greater selectivity and control on heterogeneous catalysis, a proven process used to create chemicals in nearly all areas outside of pharmaceutical research, which employs homogeneous catalysis.

Scientists have been looking for ways to exert greater selectivity in heterogeneous catalysis in an effort to expand its application and extend "green chemistry" benefits of reduced byproducts and waste, Tsung said.

The key to the nanocrystal is the extremely precise structure of the metal-organic framework, Tsung said, which gives the skin an intricate network of pore-like passages through which select gases or liquids can pass before contacting the catalyst and triggering the desired reaction.

"We can make these pores very precisely, just like your skin or like the membrane surrounding a cell," Tsung said. "We can change their composition and chemical properties in order to accept or reject certain types of reactions. That is a level of control chemists in a variety of fields are eager to see nurtured and refined."


Story Source:

The above story is based on materials provided by Boston College. Note: Materials may be edited for content and length.


Journal Reference:

  1. Chun-Hong Kuo, Yang Tang, Lien-Yang Chou, Brian T. Sneed, Casey N. Brodsky, Zipeng Zhao, Chia-Kuang Tsung. Yolk–Shell Nanocrystal@ZIF-8 Nanostructures for Gas-Phase Heterogeneous Catalysis with Selectivity Control. Journal of the American Chemical Society, 2012; 134 (35): 14345 DOI: 10.1021/ja306869j

Cite This Page:

Boston College. "Thin-skinned catalyst for chemical reactions: Yolk-shell nanocrystal structure offers greater selectivity for heterogeneous catalysis." ScienceDaily. ScienceDaily, 13 December 2012. <www.sciencedaily.com/releases/2012/12/121213085210.htm>.
Boston College. (2012, December 13). Thin-skinned catalyst for chemical reactions: Yolk-shell nanocrystal structure offers greater selectivity for heterogeneous catalysis. ScienceDaily. Retrieved November 22, 2014 from www.sciencedaily.com/releases/2012/12/121213085210.htm
Boston College. "Thin-skinned catalyst for chemical reactions: Yolk-shell nanocrystal structure offers greater selectivity for heterogeneous catalysis." ScienceDaily. www.sciencedaily.com/releases/2012/12/121213085210.htm (accessed November 22, 2014).

Share This


More From ScienceDaily



More Matter & Energy News

Saturday, November 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Toyota's Hydrogen Fuel-Cell Green Car Soon Available in the US

Toyota's Hydrogen Fuel-Cell Green Car Soon Available in the US

AFP (Nov. 21, 2014) Toyota presented its hydrogen fuel-cell compact car called "Mirai" to US consumers at the Los Angeles auto show. The car should go on sale in 2015 for around $60.000. It combines stored hydrogen with oxygen to generate its own power. Duration: 01:18 Video provided by AFP
Powered by NewsLook.com
Google Announces Improvements To Balloon-Borne Wi-Fi Project

Google Announces Improvements To Balloon-Borne Wi-Fi Project

Newsy (Nov. 21, 2014) In a blog post, Google said its balloons have traveled 3 million kilometers since the start of Project Loon. Video provided by Newsy
Powered by NewsLook.com
NSA Director: China Can Damage US Power Grid

NSA Director: China Can Damage US Power Grid

AP (Nov. 20, 2014) China and "one or two" other countries are capable of mounting cyberattacks that would shut down the electric grid and other critical systems in parts of the United States, according to Adm. Michael Rogers, director of the National Security Agency and hea Video provided by AP
Powered by NewsLook.com
Latest Minivan Crash Tests Aren't Pretty

Latest Minivan Crash Tests Aren't Pretty

Newsy (Nov. 20, 2014) Five minivans were put to the test in head-on crash simulations by the Insurance Institute for Highway Safety. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins