Gold Catalysis

Chemistry
Masatake Haruta
Professor, Department of Applied Chemistry, Graduate School of Urban Environmental Sciences, Tokyo Metropolitan University, Tokyo, Japan
Graham J. Hutchings
Professor of Physical Chemistry and Director of the Cardiff Catalysis Center, Cardiff University, Cardiff, Wales, UK

Haruta and Hutchings are suggested as joint possible Nobel Prize winners “for independent foundational discoveries of catalysis by gold”

Back in the 1980s, Haruta initiated interest in the chemistry of gold by showing it had catalytic properties. Then, in the 2000s, Hutchings took gold chemistry to new heights.

Long regarded as the least reactive of metals, gold was unexpectedly revealed to be an excellent catalyst by Haruta in 1985 (Abstracts of Papers of the American Chemical Society, 189: 171, April). This was further explained in a 1987 paper he published on a gold catalyzed reaction: the oxidation of CO at very low temperatures (Chemistry Letters, 2: 405-8). This has been cited more than 1,000 times. Haruta’s definitive review of 1997 (Catalysis Today, 36[1]: 153-66) has attracted more than 2,000 citations.

Haruta has demonstrated that colloidal gold in the form of nano-sized clusters, of diameter 5 nanometers or less, can act as a remarkable and selective catalyst, especially for reactions involving oxygen O2. He has shown that the catalytic activity depends on cluster size, method of preparation, and support material. His methods of making them, using wet or dry processes, are now used all over the world. In some cases it can produce clusters with fewer than 20 atoms, but 200-atom clusters are the norm. Under the right conditions, gold can catalyze all kinds of reactions ranging from the partial oxidation of hydrocarbons to the hydrogenation of unsaturated carbonyl compounds, the latter previously regarded as the domain of platinum and palladium catalysts.

Hutchings has advanced gold catalysis with equally innovative ways as summarized in his 2006 review in Angewandte Chemie International Edition, 45[47]: 7896-7936, which has also attracted more than 1,000 citations. His research contribution to this field has been to extend the range of reactions that can advantageously be catalyzed by gold nanoparticles, such as the oxidation of primary alcohols to aldehydes using a gold-palladium/titanium dioxide combination and without the need for a solvent. The rapid synthesis of hydrogen peroxide, H2O2, from hydrogen and oxygen, and without the formation of water as a by-product, has been a notable success, reported in 2002.

Gold catalysts could be a major step in the greening of the chemical industry, because they lead to cleaner reactions with fewer by-products. Examples of this from Hutchings’ research are the epoxidation of propylene and the formation of secondary amines.

Commentary on the Chemistry Laureates by John Emsley, Chemistry correspondent, ScienceWatch