Navigation Links
Fair trade
Date:6/16/2008

This release is available in German.

Because of its toxicity and the dangers involved in handling it, tetrachloromethane (carbon tetrachloride, CCl4) can no longer be used or produced in many countries. However, the processes used in the production of other chlorinated hydrocarbons, such as chloroform (trichloromethane, CHCl3), also produce CCl4 as a byproduct. What is the best way to get rid of this unwanted substance? A team headed by Bert M. Weckhuysen at the University of Utrecht (Netherlands) has now found an interesting new approach that may lead to effective recycling. As the researchers report in the journal Angewandte Chemie, a lanthanum chloride catalyst induces CCl4 and its reaction partner dichloromethane (CH2Cl2) to exchange one chlorine atom for a hydrogen atom, forming nearly 100 % of the desired CHCl3.

In order to increase the catalyst surface, lanthanum chloride (LaCl3) was deposited onto carbon nanofiber supports. This results in a highly active, selective, and stable catalyst to facilitate the hydrogenchlorine exchange between CCl4 and CH2Cl2. "Computer calculations suggest," says Weckhuysen, "that the mechanism occurs by way of two separate hydrogenchlorine exchange reactions." It appears that the surface of the LaCl3 catalyst contains not only the terminal chlorine atoms of the crystal lattice, but also other weakly adsorbed species. CH2Cl2 swaps one of its hydrogen atoms for one such weakly bound chlorine atom. It leaves behind the hydrogen atom, which is in turn weakly adsorbed to the catalyst surface. This hydrogen atom can be taken up by CCl4, which in turn leaves one of its chlorine atoms behind on the catalyst surface. Both of these reaction steps produce chloroform exclusively; no byproducts come into play.

This new catalytic reaction is astonishing in that it was previously assumed that the presence of oxygeneither in the gas phase or bound to the crystal lattice of the catalystis required for such reactions. Says Weckhuysen: "We are reporting for the first time a lanthanum-based catalyst material that can activate both C-H and C-Cl bonds in the absence of oxygen." (2193 characters)


'/>"/>

Contact: Bert M. Weckhuysen
b.m.weckhuysen@uu.nl
31-302-534-328
Wiley-Blackwell
Source:Eurekalert  

Related biology news :

1. Stinger Systems To Offer Taser Trade-In Program
2. Global trade in tiger shrimp threatens environment
3. Markets of biodiversity and equity in trade: An illusion?
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
Fair trade
(Date:3/30/2017)... -- On April 6-7, 2017, Sequencing.com will host the world,s ... at Microsoft,s headquarters in Redmond, Washington ... health and wellness apps that provide a unique, personalized ... is the first hackathon for personal genomics and the ... the genomics, tech and health industries are sending teams ...
(Date:3/29/2017)...  higi, the health IT company that operates the ... , today announced a Series B investment from ... The new investment and acquisition accelerates higi,s strategy to ... population health activities through the collection and workflow integration ... collects and secures data today on behalf of over ...
(Date:3/24/2017)... The Controller General of Immigration from Maldives Mr. ... have received the prestigious international IAIR Award for the most innovative ... ... Maldives Immigration ... Algeen (small picture on the right) have received the IAIR award for ...
Breaking Biology News(10 mins):
(Date:7/20/2017)... ... July 20, 2017 , ... Resoundant, Inc. is pleased ... centers around the U.S. that offer MR Elastography for liver fibrosis staging. ... biopsy for staging liver fibrosis assessment. , “MRE:connect was created in response to ...
(Date:7/20/2017)... ... July 20, 2017 , ... ... digital pathology and artificial intelligence Tuesday, July 25, during the Association of Pathology ... Johns Hopkins Medicine. , Baras, Associate Director of Pathology Informatics, will present ...
(Date:7/18/2017)... , ... July 18, 2017 , ... ... accelerate pharmaceutical and biotherapeutics development, announces the launch of a new NTA biosensor ... chip enables researchers to study the kinetics of polyhistidine-tagged (His-tagged) molecules quickly and ...
(Date:7/18/2017)... ... ... Blood centers traditionally see a dangerous drop of blood donations during the ... community blood centers as high schools are out and many frequent donors are on ... up with the South Texas Blood & Tissue Center (STBTC), a subsidiary ...
Breaking Biology Technology: