In situ electrochemical regeneration of deactivated coated foam catalysts in a Robinson–Mahoney basket reactor: Example of Pd/C for nitrobenzene hydrogenation

• Cylindrical foams were coated with Pd/C and used in nitrobenzene hydrogenation.
• The Pd/C/foams were used in place of the basket of a Mahoney–Robinson reactor.
• Electrochemical regenerations were performed after deactivation of the catalyst.
• Successive in situ regenerations of the coated catalyst were successfully carried out.
• No significant loss of catalyst was observed after regeneration.

The electrochemical in situ regeneration of spent Pd/C/foam catalysts was investigated using a modified Mahoney–Robinson reactor (RM). The same reactor was used for reaction and regeneration experiments with and without removal/weighing of the catalyst between each measurement. The feasibility of the electrochemical regeneration was assessed by monitoring the catalyst activity versus cumulative turnover number (TON). The results showed that the catalyst activity was fully recovered after regeneration and that the catalyst had the same deactivation rate after several reaction/regeneration cycles. The influence of the foam pretreatment step and of the pH electrolyte solution on the catalyst loss was also studied. A basic pretreatment of the foam before the catalyst coating led to a significant improvement of the catalyst adherence on the foam.

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