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Gold is utilized as a catalyst in various industrial processes. A gold alloy is one such catalyst that is already used for producing vinyl acetate monomer (VAM).
Introduction to Gold Catalysts
A catalyst can be defined as a material or substance that speeds up the rate of a chemical reaction without being consumed by the reaction itself. Catalysts are vital components of many different industrial processes used to produce foodstuffs, chemicals, and other materials.
One of the first intentional applications of catalysts was perhaps the fermentation of sugar to make alcohol. Another common day-to-day application is the use of catalytic converters on cars for controlling exhaust emissions.
Gold as a Catalyst Material
Until now, gold has been overlooked by a majority of the researchers as a potential industrial catalyst. But now, the following reactions have been shown to be effectively catalyzed by gold catalysts:
- Catalytic combustion of hydrocarbons
- Oxidation of carbon monoxide, including selective oxidation in a hydrogen stream
- Hydrogen + oxygen reaction to form hydrogen peroxide
- Hydrochlorination of ethylene
- Oxidation of glucose to gluconic acid
- Removal of sulfur dioxide and hydrogen sulfide
- Oxidative removal of mercury
- Oxidative decomposition of dioxins
- Reduction of NOx with hydrogen, carbon monoxide, or propene
- Decomposition of ozone
- Selective hydrogenation, for example, of dienes and alkynes to mono-olefins
- Selective oxidation, for example, epoxidation of olefins
- Water-gas shift
- Synthesis of vinyl acetate from ethane, oxygen, and acetic acid
When gold is used as a catalyst, it has to be prepared in a careful and unique manner in order to achieve a very small gold particle size.
Gold is set to take its position alongside other valuable metals (like silver and platinum group metals) as an essential catalyst in various industrial processes and applications. As mentioned above, a gold alloy is already used as a catalyst in the commercial production of VAM.
Project AuTEK, based in South Africa, is one of the top organizations looking forward to commercializing new and significant catalytic applications of gold.