Palladium black explained

Palladium black is a coarse, sponge-like form of elemental palladium which offers a large surface area for catalytic activity. It is used in organic synthesis as a catalyst for hydrogenation reactions.^[1]

The term palladium black is also used colloquially to refer to a black precipitate of elemental palladium, which forms via decomposition of various palladium complexes.^[2]

Preparation

Palladium black is typically prepared from palladium(II) chloride or palladium(II)-ammonium chloride. The palladium chloride process entails the formation of palladium hydroxide using lithium hydroxide followed by reduction under hydrogen gas^[3] while the palladium(II)-ammonium chloride route employs a solution of formic acid followed by the precipitation of the catalyst using potassium hydroxide.^[4]

See also

• Platinum black
• Platinum dioxide
• Platinum on carbon
• Palladium on carbon
• Rhodium-platinum oxide

Notes and References

1. Book: Nishimura. Shigeo. Handbook of Heterogeneous Catalytic Hydrogenation for Organic Synthesis. 2001. Wiley-Interscience. New York. 9780471396987. 34–35. 1st.
2. Iwasawa. Tetsuo. Tokunaga. Makoto. Obora. Yasushi. Tsuji. Yasushi. 2004-06-01. Homogeneous Palladium Catalyst Suppressing Pd Black Formation in Air Oxidation of Alcohols. Journal of the American Chemical Society. 126. 21. 6554–6555. 10.1021/ja031936l. 15161274. 0002-7863.
3. Nishimura. Shigeo. Itaya. Takashi. Shiota. Michio. Reactions of cycloalkanones in the presence of platinum-metal catalysts and hydrogen. Chemical Communications. 1967. 9. 422–423. 10.1039/C19670000422.
4. Zelinsky. N.. Glinka. N.. Über gleichzeitige Reduktions- und Oxydationskatalyse. Berichte der Deutschen Chemischen Gesellschaft. 1911. 44. 3. 2305–2311. 10.1002/cber.19110440347.