A highly active nanocomposite silica-carbon supported palladium catalyst for decarboxylation of free fatty acids for green diesel production: Correlation of activity and catalyst properties

• A novel process was proposed for nanocomposite Si-C supported Pd catalyst synthesis.
• Oleic acid decarboxylation was conducted in the absence of H2 input.
• A Pd/Si-C-4 catalyst displayed excellent activity for decarboxylation of oleic acid.
• The catalyst maintained stable activity for green diesel production for 16 days.
• The highly active catalyst possessed well-distributed Pd on low acidic support.

A class of Pd catalyst supported on a silica-activated carbon nanocomposite for free fatty acid (FFA) decarboxylation was developed, and displayed excellent activity and operation stability selectively for the green diesel hydrocarbons formation in the absence of H2 under mild reaction conditions. Six catalysts containing 5 wt% Pd were prepared by systematically varying the silica content in the support. In addition to the effect of particle size, the impact of catalyst preparation method on the activity and selectivity was elucidated. A 5 wt% Pd/Si-C-4 catalyst maintained stable activity for 16 days under reaction conditions of 1.5 MPa and 300 °C. Although a continuous supply of H2 was not necessary, H2 treatment was essential to restore the catalytic activity and the desired product selectivity. Characterization of the catalyst revealed that the highly active Pd/Si-C-4 catalyst has easily accessible and well-distributed metallic Pd nanoparticles inside the hybrid mesopores.

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