Controlling hydrogenation selectivity with Pd catalysts on carbon nitrides functionalized silica

• S-C_T composites with different CNx loadings were prepared by changing the treatment temperature (T).
• Pd catalysts with controlled particle size were prepared using S-C_T composites as support.
• The Pd catalysts show high conversion and selectivity for a variety of hydrogenation reactions.
• The Pd catalysts are stable in the COD hydrogenation reaction, even after reusing for 6 cycles.

We report here the synthesis of Pd nanoparticles (NPs) supported on a carbon nitrides–silica composite (S-C_T) and its application as a catalyst in the hydrogenation of 1,5-cyclooctadiene. While the mesoporous silica provides a high surface area, the carbon nitrides (CNx) stabilize the Pd NPs, and the Pd particle size can be controlled by varying the treatment temperature (T) for the composite. The Pd catalysts show good conversion and selectivity for hydrogenation both at elevated pressure (50–80 °C, H2 pressure 2 MPa) and at atmospheric pressure, even at zero degrees, and the selectivity can be well controlled owing to the controlled particle size of the Pd NPs. Furthermore, after reusing the catalyst 6 times, no loss in selectivity is observed while the conversion is slightly decreased to about 15%. Thus, an active Pd catalyst with prolonged lifetime for hydrogenation is observed when carbon nitrides-silica composites are used as support.

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