PALLADIUM ON CARBON

Palladium on carbon
(Pd/C)
CAS 7440-05-3 (palladium)

Pd/C

Black powder
mp 1555 °C, bp 3167 °C (palladium)
Insoluble in water

Odorless

LD₅₀ oral (rat) 200 mg/kg (palladium chloride)

LC₅₀ intratracheal (rat) 6 mg/kg (palladium chloride)

May ignite on exposure to air, particularly when containing adsorbed hydrogen; readily causes ignition of flammable solvents in the presence of air.

Very little information is available on the toxicity of palladium and its compounds. There is some evidence that chronic exposure to palladium particles in dust can have toxic effects on the blood and respiratory systems. Finely divided carbon is irritating to mucous membranes and the upper respiratory tract.

Palladium on carbon catalysts containing adsorbed hydrogen are pyrophoric, particularly when dry and at elevated temperatures. Palladium on carbon catalysts prepared by formaldehyde reduction are less pyrophoric than those reduced with hydrogen. Finely divided carbon, like most materials in powder form, is capable of creating a dust explosion.

Catalysts prepared on high surface area supports are highly active and readily cause ignition of hydrogen/air and solvent/air mixtures. Methanol is notable for easy ignition because of its high volatility. Addition of catalyst to a tetrahydroborate solution may cause ignition of liberated hydrogen.

Because of its high potential for ignition, palladium on carbon should be handled using the "basic prudent practices" of Chapter 5.C, supplemented by the additional precautions for work with reactive and explosive chemicals (Chapter 5.G). In particular, palladium on carbon should always be handled under an inert atmosphere (preferably argon), and reaction vessels should be flushed with inert gas before the catalyst is added. Dry catalyst should never be added to an organic solvent in the presence of air. Palladium on carbon recovered from catalytic hydrogenation reactions by filtration requires careful handling because it is usually saturated with hydrogen and will ignite spontaneously on exposure to air. The filter cake should never be allowed to dry, and the moist material should be added to a large quantity of water and disposed of properly.

In the event of skin contact, immediately wash with soap and water and remove contaminated clothing. In case of eye contact, promptly wash with copious amounts of water for 15 min (lifting upper and lower lids occasionally) and obtain medical attention. If palladium on carbon is ingested, obtain medical attention immediately. If large amounts of dust are inhaled, move the person to fresh air and seek medical attention at once.

In the event of a spill, remove all ignition sources, wet the palladium on carbon with water, place in an appropriate container, and dispose of properly. Respiratory protection may be necessary in the event of a large release in a confined area.

Excess palladium on carbon and waste material containing this substance should be covered in water, placed in an appropriate container, clearly labeled, and handled according to your institution's waste disposal guidelines.

The information in this LCSS has been compiled by a committee of the National Research Council from literature sources and Material Safety Data Sheets and is believed to be accurate as of July 1994. This summary is intended for use by trained laboratory personnel in conjunction with the NRC report Prudent Practices in the Laboratory: Handling and Disposal of Chemicals. This LCSS presents a concise summary of safety information that should be adequate for most laboratory uses of the title substance, but in some cases it may be advisable to consult more comprehensive references. This information should not be used as a guide to the nonlaboratory use of this chemical.

Copyright 1995 National Academy of Sciences. All rights reserved.