Chemists find novel method to control catalysis
19 Dec 2016 by qmjwtjwqdb.d qmjwtjwqdb.d
Scientists in Canada have discovered a novel technique that enables them to manipulate catalytic reactions.
Scientists in Canada have discovered a new technique that enables them to manipulate catalytic reactions.
By using a combination of experiments and a mathematical model, they discovered that the position of a molecule on a copper catalyst’s surface enabled the breaking of one chemical bond 100 times faster than the other.Professor John Polanyi, chemistry Nobel Prize winner at the University of Toronto and co-author, said: “We found that the microscopic positioning of the molecule relative to the catalytic surface below, rendered the catalyst highly bond-specific. The closer the alignment of the bonds of the molecule to the rows of atoms in the catalyst, the more selective the reaction was.”
The research group were investigating the breaking of iodobenzene’s carbon-iodine bonds, using copper as a catalyst. As part of the study, a scanning tunnelling microscope was used to initiate the reaction by attaching an electron to iodobenzene.
Kelvin Anggara, a PhD student in Polanyi’s’ research group and first author, said: “We observed acceleration in the reactivity of the carbon-to-iodine bonds when those bonds were aligned along rows of copper atoms in the catalyst, as compared to the bonds aligned across the copper rows.
“The copper atoms along the rows were slightly closer together, by about the diameter of a single atom, than the atoms across the rows. This closer spacing promoted the breaking of bonds lying along the rows."A mathematical model created by the researchers enabled the creation of a computer-generated movie of the atomic motions in bond-breaking at the copper surface. This video allowed them to see why copper catalysed bonds along its rows.
After receiving the Nobel Prize for observing the molecular motions in chemical reactions occurring in gases, Professor Polanyi turned his attentions to the reactions of individual molecules on well-defined surfaces. He said: “The challenge for the future will be to fabricate metal catalysts embodying atomic patterns that speed chemical reactions along pathways that lead to desired products.”
The study was published in Nature Communications.
