Influence of catalyst preparation on the contribution of homogeneous and heterogeneous steps to the selectivity in nitroaliphatic compounds hydrogenation

• We have studied 2-methyl-2-nitropropane hydrogenation.
• We consider homogeneous steps, reactions on the support and on the metal.
• Hydrogen activation takes place on the metal, and may spillover and jumpover.
• Organic reactants and intermediates may be activated on the metal and on the carbon support.
• A synergic effect is observed, depending on the chemical surface of the support.

2-Methyl-2-nitropropane hydrogenation proceeds along a rake scheme that may encompass homogeneous steps, reactions on the support and on the metallic phase as well. This complexity makes it useful as a test reaction. Reaction rates, selectivities and intermediate compounds accumulation provide experimental information on the modification of catalytic parameters such as support functionality and metallic dispersion. Experiments were carried out in homogeneous phase, on bare carbon supports, with mechanical mixtures of bare carbon supports and carbon-supported catalysts, and with catalysts prepared on modified supports. We have shown that hydrogen activation takes place on the metal and that organic reactants and intermediates may be activated on the metal and on the carbon support as well and may react with hydrogen available after spillover and jumpover migrations.

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