With the fall in palladium prices and the rise in platinum prices palladium’s cost-effectiveness in chemical applications has become apparent. Various chemical applications use palladium, including the manufacture of paints, adhesives, fibers and coatings. Palladium is used in the production of purified terephthalic acid, which is a precursor to polyesters and to polyethylene terephthalate a plastic resin used in packaging of film and glass laminates.
PGM catalysts for nitric acid production take the form of a gauze made out of fine wire. Palladium is used in the production of catchment gauze used in the making of nitric acid for the manufacture of nitrogen fertilizers.
 When nitric acid was first produced commercially in 1904, a platinum-only catalyst was used. Rhodium was later added for strength and to reduce the amount of platinum lost during conversion of the gas. Palladium-based “catchment” or “getter” gauze was introduced in 1968 to further reduce losses of platinum and rhodium, which can be as high as 300 mg per ton of acid produced. The catchment sits downstream of the gas flow and collects pgm vaporized from the catalyst.
Ethanol is produced using palladium catalysts through the “Wacker Process”. This process manufactures ethanol by oxidizing ethane, yielding 95% acetaldehyde which is converted to the ethanol. The process has good economics due to the abundance of ethylene.
The reaction is catalyzed by PdCl2 and CuCl2. It involves the reaction of ethylene with palladium chloride in water. Palladium is thereby reduced to palladium black. To make the reaction catalytic, palladium is reoxidized by reaction with copper chloride and oxygen. The process is run in one vessel at slightly elevated temperatures and pressures (50-130 °C and 3-10 atm).
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[Pd(0)/Cu(II)] |
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| C2H4 + 1/2 O2 |
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CH3CHO |
Palladium is also used in chemical processes that require hydrogen exchange between two reactants, such as that which produces butadiene and cyclohexane, the raw materials for synthetic rubber and nylon.
Another important use as a catalyst is in the manufacture of polyester. Learn the story of the development of the technique. |
