Influence of Solvents and Additives on the Pyrophoricity of Palladium on Carbon Catalyst after Hydrogenation

We performed a systematic investigation of the conditions causing or preventing self-ignition of spent palladium on a carbon catalyst after hydrogenation reactions. The solvent used for hydrogenation plays a major role. We compared the pyrophoricity of a filtered catalyst, produced with 11 commonly used hydrogenation solvents. Self-ignition was only observed with alcoholic solvents. We also show that self-ignition of spent catalyst can be prevented by an efficient water rinse and/or addition of thiophene. A method is also presented to evaluate the risk of spontaneous ignition of the catalyst cake after hydrogenation with palladium on carbon in a systematic way.