I think both can be referred to as "Palladium on carbon" according to what I can see. "Palladium on carbon" is often referred to as Pd/C, is a form of palladium used for catalysis per last website below. (please see).

http://www.weblio.jp/content/パラジウム炭素

パラジウム炭素
出典: フリー百科事典『ウィキペディア（Wikipedia）』 (2010/01/20 19:01 UTC 版)
パラジウム炭素（パラジウムたんそ、palladium on carbon）とは、パラジウム触媒を有機合成で用いる際の一形態で、活性炭を担体としてその上にパラジウム(0)を分散、担持させたもののこと。水素化還元反応などに用いられる。反応式では Pd/C, Pd-C などと表される。パラジウムカーボンとも呼ばれる。
http://wpedia.goo.ne.jp/wiki/パラジウム炭素
パラジウム炭素（パラジウムたんそ、palladium on carbon）とは、パラジウム触媒を有機合成で用いる際の一形態で、活性炭を担体としてその上にパラジウム(0)を分散、担持させたもののこと。水素化還元反応などに用いられる。反応式では Pd/C, Pd-C などと表される。パラジウムカーボンとも呼ばれる。

http://en.wikipedia.org/wiki/Palladium_on_carbon
Palladium on carbon
From Wikipedia, the free encyclopedia
Palladium on carbon, often referred to as Pd/C, is a form of palladium used for catalysis. It is usually used for catalytic hydrogenations in organic chemistry. When the metal is distributed over finely divided carbon the surface area is larger and the catalyst more reactive.
Palladium-on-carbon has also been used as the palladium(0) catalyst in the Suzuki reaction, Stille reaction[1], and related reactions.


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Note added at 4 hrs (2011-04-25 00:47:27 GMT)
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--- Here are a couple more reference websites:
http://www.vineethchemicals.com/palladium_on_carbon.htm
Palladium on Activated Charcoal also known as Palladium on Carbon (Pd on C) is a mild hydrogenation catalyst. It is generally a catalyst of choice when the functional group to be hydrogenated is a part of a molecule which has also got some other functional group capable of getting hydrogenated. It is also a catalyst of choice for getting a specific type of isomer.

http://www.nap.edu/openbook.php?record_id=4911&page=370
LABORATORY CHEMICAL SAFETY SUMMARY: PALLADIUM ON CARBON
Substance Palladium on carbon
(Pd/C)
CAS 7440-05-3 (palladium)

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Note added at 5 hrs (2011-04-25 02:12:08 GMT)
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In the website above it says "Palladium on Activated Charcoal also known as Palladium on Carbon (Pd on C) is a mild hydrogenation catalyst." Perhaps this is where the words "charcoal 炭素" and "carbon カーボン" come into play in your translation.