That drum of platinum complex we use in the workshop every day traces its technical lineage to a paper published in 1957; and the bond between platinum catalysts and human industry goes back more than another hundred years beyond that. Follow this thread once through, and you'll have much firmer grounding for the claim that "the silicone industry has no alternative to platinum."

1. The Starting Point: Platinum That Lights Itself

In 1823 the German chemist Döbereiner made his famous "Döbereiner's lighter": hydrogen gas jetted onto platinum sponge (finely divided platinum) and burned spontaneously, with no open flame required. This was the first time humanity turned platinum's catalytic properties into a usable device.

What it proved remains crucial today — platinum can dissociate and activate the hydrogen molecule at ambient temperature. The spontaneous ignition of platinum black described in the previous article rests on exactly the same principle.

2. Into Heavy Industry: Platinum–Rhodium Gauze and Nitric Acid

The Ostwald process oxidizes ammonia over a platinum–rhodium alloy gauze into nitric oxide, which is then converted into nitric acid. This route supplied the nitrogen source that underpinned the fertilizer and explosives industries, and platinum–rhodium gauze remains mainstream equipment to this day — adding rhodium improves the mechanical strength of the gauze and reduces platinum's volatilization loss at high temperature.

This is also one of the origins of the precious metals recovery industry. The bulk of our plant's recovery business comes precisely from retired platinum–rhodium gauze.

3. The Oil Era: Catalytic Reforming

In the late 1940s, platinum supported on alumina was put to use in the catalytic reforming of naphtha, converting low-octane straight-run gasoline into high-octane reformate while producing hydrogen and aromatics as by-products. UOP's Platforming process is the representative of this line.

From this step onward, platinum was no longer a laboratory curiosity but a pillar material of the energy industry.

4. Speier's Discovery: The Key to the Silicone Industry

In 1957, John Speier of Dow Corning reported that chloroplatinic acid (H₂PtCl₆, usually formulated as an isopropanol solution) efficiently catalyzes the addition of silicon–hydrogen bonds across olefin double bonds. That is hydrosilylation.

Its significance can hardly be overstated — without this reaction there would be no addition-cure silicone rubber, silicone fluids, silicone gels or silicone resins as we know them today. Speier brought platinum out of high-temperature heavy industry and into the low-temperature liquid-phase systems of fine chemicals, and chloroplatinic acid has since been known for decades as Speier's catalyst.

5. Speier's Three Weak Points

After decades of use, the problems became equally clear:

Chlorine residue. The chlorine introduced by chloroplatinic acid remains in the finished product, impairing electrical performance and causing yellowing.

Unstable coordination. Platinum's coordination environment shifts easily, activity varies from batch to batch, and the process window is hard to control.

Mediocre compatibility. It has to be charged with the help of a foreign solvent such as isopropanol, and solvent residue then becomes a new problem in its own right.

6. Karstedt's Leap: Stabilizing Platinum with the System's Own Molecules

In the 1970s, B. D. Karstedt at General Electric produced a complex of platinum(0) with a vinylsiloxane — most commonly divinyltetramethyldisiloxane. The elegance of the idea lies here: the ligand is no longer a foreign chlorine species, but a vinylsiloxane molecule belonging to the silicone system itself.

What followed was a whole chain of improvements: full compatibility with silicone materials, so no foreign solvent is needed; extremely low chlorine content, so products resist yellowing and perform better electrically; platinum present in a well-defined zero oxidation state, giving high activity and batch-to-batch consistency; and the vinyl groups on the ligand are themselves reaction substrates — the catalyst, in effect, brings its own rations.

Karstedt's catalyst thereupon became the mainstream choice for addition-cure silicone rubber. Open that drum of pale yellow liquid of ours today, and its core component is exactly this.

7. The Main Thread Since: Ligand Engineering

The step from Speier to Karstedt set the tone for the entire industry — the same platinum atom, a different ligand, a different performance. All subsequent evolution has travelled this road:

Pairing with acetylenic alcohol inhibitors, turning pot life into a controllable parameter;

Platinum alloying, core–shell architectures and single-atom platinum, all aimed at raising the efficiency per unit of platinum;

Low-platinum formulations, holding cost competitiveness through swings in the platinum price.

Conclusion

Two hundred years of history really contain only one thread: humanity steadily learning to use platinum with greater precision. From igniting hydrogen, to oxidizing ammonia and reforming gasoline, to today spreading platinum atoms out one by one across a support — every step has been about making less platinum do more work.


Diethylenetetramethyldisiloxane platinum complex (platinum catalyst) IOTA 8114