Silver News
Silver Maintains Its Key Markets for Catalysis
By Jeffrey R. Ellis, Adjunct Professor of Chemistry & Environmental Science, Florida International University
About 60 million ounces of silver are used annually as a catalyst in the production of industrial chemicals. Of that amount, about 57 million can be reclaimed and reused, but an additional three million
ounces annually of new silver are needed to make up the shortfall.
More than 90 percent of this catalytic silver is used to produce ethylene oxide, a chemical that is often directly converted into ethylene glycol. Ethylene glycol is primarily used for the manufacture of polyester fibers, containers, films and sheets. Ethylene oxide is also used as a fumigant, a sterilizing gas and for the production of other chemicals.
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Silver catalyzed oxidation is the
only commercial method for manu-facturing ethylene oxide because of silver’s performance as a cost effective and efficient catalyst.
The recent worldwide recession, resulting in a lowering of ethylene oxide production in addition to consolidation among silver catalyst suppliers, has
resulted in lower growth in the use of silver catalysts over the last two years. Even so, low to moderate growth is expected in the next few years. Most of the growth will be in East Asia, China, India, Taiwan and South Korea, which are major producers of ethylene oxide. New capacity is coming on stream in Malaysia and in the Middle East,
mainly Saudi Arabia and Kuwait. Much of the Middle East output is converted to ethylene glycol for safer and easier shipping. Dow Chemical, Sabic and
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Shell are the largest producers of ethylene oxide, with a 42 percent share of the worldwide market.
Silver is also used in the production of formaldehyde by catalytic oxidation of methanol, but newer plants prefer iron oxide/molybdenum oxide technology. The mixed oxide method can use lower temperatures and is said to be 15 percent more efficient and selective than the silver process. Still, silver is used to produce 20 to 30 percent of the world’s formaldehyde, mainly in plants which are at least 25 years old. The main advantage of silver-based technology is that initial capital and start-up costs are lower. For small plants, silver-based technology offers a higher lifetime benefit to cost ratio.
In related news, The U.S. House of Representatives passed legislation on April 11 which includes a provision to initiate a three-year federal government program to study the potential of gold and silver as an industrial and automotive catalyst. This federally authorized research could lead to new developments in catalysis and allow gold and silver to replace more expensive platinum-group metals which are currently used in emission controls on automobiles and industrial machinery. The U.S. Senate will debate its own version of the Energy Policy Act of 2003 (H.R. 6), which includes the catalysis provision, later this spring.
Silver News - Second Quarter 2003
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