Research paperPolymer-based spherical activated carbon as catalytic support for hydrodechlorination reactions

- Pd/PBSAC catalyst has proved to be active, easily-recoverable and durable for the HDC reaction.
- The catalyst preparation involved H2SO4 treatment, ion-adsorption of Pd and gas thermal treatment.
- The presence of both Pd0 and Pdn+ species was required to obtain active HDC catalysts.
- An expanded kinetic model accounting for sorption and HDC fitted successfully the experimental data.
- Pd/PBSAC catalyst showed a remarkable stability and negligible deactivation upon long-term application.

In this work, polymer-based spherical activated carbon (PBSAC) (dp = 500 μm) has been used as support to synthesize several Pd/PBSAC (1% wt.) catalysts. These catalysts have been tested in the hydrodechlorination (HDC) of 4‐chlorophenol (4-CP) in aqueous phase under ambient-like conditions (30 °C, 1 atm) at [4-CP]0 = 3.9 mmol L−1; [catalyst]0 = 1 g L−1 and 50 N mL H2 min−1. A sequential calcination (200 °C, air atmosphere) − reduction (80 °C, H2 atmosphere) treatment was required to obtain active HDC catalysts with a convenient proportion of zero-valent and electrodefficient Pd species. This catalyst allowed to achieve complete conversion of 4-CP in 90 min reaction time, giving rise to phenol as main reaction product. An expanded kinetic model accounting for both consecutive reaction and sorption processes was used to successfully fit the experimental data. The values obtained for the effective rate constant of 4-CP disappearance (3.26-10.88 × 10−4 s−1) and apparent activation energy (31.6 kJ mol−1) were close to the previously reported for powdered supported Pd catalysts. Remarkably, the catalyst showed a high stability in long-term continuous application (100 h on stream).

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