Palladium on carbon catalyst (5% Pd). A suspension of 93 g. of nitric acid-washed Darco G-60 (Note 10) in 1.2 l. of water contained in a 4-l. beaker
(Note 3) and (Note 4) is heated to 80°. To this is added a solution of 8.2 g. (0.046 mole) of palladium chloride in 20 ml. (0.24 mole) of
concentrated hydrochloric acid and 50 ml. of water (Note 2). Eight milliliters (0.1 mole) of 37% formaldehyde solution is added. The suspension is
made slightly alkaline to litmus with 30% sodium hydroxide solution, constant stirring being maintained. The suspension is stirred 5 minutes longer.
The catalyst is collected on a filter and washed ten times with 250-ml. portions of water. After removal of as much water as possible by filtration,
the filter cake is dried (Note 11), first in air at room temperature, and then over potassium hydroxide in a desiccator. The dry catalyst (93–98 g.)
is stored in a tightly closed bottle.
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