C&EN: IT'S ELEMENTAL: THE PERIODIC TABLE

PLATINUM

RICHARD M. GROSS, DOW CHEMICAL

PLATINUM AT A GLANCE

Name: From the Spanish platina, silver.

Atomic mass: 195.08.

History: Known since ancient times. The pre-Columbian Indians of South America used platinum, but it wasn't noticed by Western scientists until 1735. Credit for its modern rediscovery is usually given to Antonio de Ulloa.

Occurrence: Occurs naturally in its native form in the Urals in Russia, as well as in Canada, South America, Colombia, and Peru. Platinum can also be extracted as a by-product of copper and nickel refining.

Appearance: Silvery white, solid metal. Lustrous, malleable, and ductile.

Behavior: Very resistant to corrosion and not volatile. Platinum salts are toxic.

Uses: Used in its pure form in jewelry since it is long-wearing and extremely white. Platinum is widely used in catalysts and has found great use in automobile catalytic converters. It is also used in semiconductors and is a component of some anticancer drugs.

When my mother's silvery white wedding ring slid off and rolled under the porch of the summer cottage in New Hampshire, I was the only one small enough to crawl beneath the porch to retrieve it. I had no idea I would, later in life, consider the material used to make that ring--platinum--one of the elements important to one of my life's pursuits.

After I found the ring, I can distinctly remember feeling sorry for my mother because it wasn't gold, like other mothers wore. I asked her about that, and I remember her answer. "This is rarer than gold," she recounted, "and it's sturdier, which means I can wear it my entire life."

So, my vast knowledge of platinum at that time was that it was used to make jewelry.

By the time I was in high school and developing a growing interest in science, I was reintroduced to platinum while learning about thermocouples. It struck me then that this was the same material as my mother's wedding ring. How interesting that there were such significantly different uses of the element.

In college, I discovered platinum was also used as the basis of important catalysts in industry--for the production of products such as sulfuric acid, nitric acid, and hydrogen cyanide.

Some of the most interesting things I learned about this magic metal were that 90% of all platinum comes from South Africa and Russia, it's extraordinarily rare, and more than 10 tons of ore has to be mined to produce a single ounce of platinum. That's twice as much ore required to produce an ounce of gold.

Early in my career, I remember learning about the development of the Platforming (platinum and reforming) process by United Oil Products (UOP) in the late 1940s. The Platforming process is one of the few breakthrough technologies that radically changed the face of the petroleum industry and helped meet the demands of the automobile industry for higher octane gasoline.

In recent years, through Dow's 50% ownership of UOP with Honeywell, I have enjoyed learning more about the details of Platforming research. For example, it was interesting to learn that the cost of this noble metal almost killed the research project before it was started and clearly drove the development of promoters to achieve great performance at low-platinum loadings.

Platinum history takes us back 3,000 years to ancient Egypt, where metalsmiths were skilled in working with this rare metal. A 2,500-year-old coffin of an Egyptian high priestess was found with the coffin's platinum-engraved hieroglyphs still polished and lustrous.

The Incas created adornments from platinum but when they were invaded by the Spanish conquistadors, platinum was declared the "solver of less value," and the conquistadors dumped great amounts of platinum into the sea because they were fearful it would become a cheap imitation of silver.


	RINGING ENDORSEMENT Though it has many commercial uses, platinum is perhaps best known for its presence in jewelry.
	CLARCO CORTES IV/REUTERS PHOTO ARCHIVE

Finally, during the 18th century, platinum's value as a metal suited for jewelry took hold, and in the 19th century, it became the standard mounting for the newly discovered gemstone, the diamond. The most famous of these diamonds--the Hope, the Jonker, and the Koh-I-Nor--are all set in platinum.

However, the largest market for platinum today is in automobile catalytic converters.

Once again, platinum is meeting the demands of society for cleaner, more environmentally friendly automobiles. Catalytic converters and, thus, platinum, have significantly increased air quality in recent decades.

Getting back to the beginning, platinum remains equally as important to the jewelry market as it is to the industrial market. So, while I've learned lots about platinum since I went searching for my mother's wedding ring, it appears as though my early lessons remain true to the element's role in our lives. And as a testament to this material, my mother continues to wear her ring, 63 years later, and it still sparkles.

Richard M. Gross is the corporate vice president of research and development and new business growth for Dow Chemical Co. He has a bachelor's degree in chemical engineering from Worcester Polytechnic Institute and a doctorate in chemical engineering from the University of Utah.

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