On the deactivation and regeneration of Pd/Al2O3 catalyst for aqueous-phase hydrodechlorination of diluted chlorpromazine solution
| Autor: | Julia Nieto-Sandoval, Zahara M. de Pedro, Macarena Munoz, Jose A. Casas, David Ortiz |
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| Rok vydání: | 2020 |
| Předmět: |
Chemistry
Inorganic chemistry Aqueous two-phase system 02 engineering and technology General Chemistry Activation energy 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences Catalysis 0104 chemical sciences law.invention Volumetric flow rate Reaction rate constant law medicine Calcination 0210 nano-technology Effluent Promazine medicine.drug |
| Zdroj: | Catalysis Today. 356:255-259 |
| ISSN: | 0920-5861 |
| DOI: | 10.1016/j.cattod.2019.06.028 |
| Popis: | The abatement of dissolved organochlorinated pharmaceuticals from water by catalytic hydrodechlorination has been scarcely studied so far, but it represents a promising process for such goal. This work aims to evaluate the feasibility of this system for the removal of chlorpromazine, one of the most used pharmaceuticals for mental disorders treatment, paying special attention to the deactivation and regeneration of the catalyst (commercial Pd/Al2O3, 1% wt.). Complete conversion of chlorpromazine (3 mg L−1) was achieved in 90 min reaction time at 25 °C and 1 atm, using a catalyst load of 0.25 g L−1 and 50 N mL min−1 H2 flow rate. Remarkably, the chlorine-free compound promazine was the single reaction product, which allowed to reduce significantly the ecotoxicity of the starting effluent (0.9 TUs) to negligible values. The experimental data were properly described by a pseudo-first order kinetic equation, obtaining a rate constant value of 5.9·10−2 min−1 at 25 °C, and 30 kJ mol−1 as activation energy. Despite the high activity of the catalytic system, it suffered a significant deactivation upon consecutive uses, which was associated to the selective interaction between promazine and Pd active sites. A number of regeneration methods including both thermal (calcination, calcination-reduction) and chemical (NaClO, H2O2, KMnO4) treatments were investigated. Remarkably, aqueous-phase NaClO (750 mg L−1) regeneration allowed to recover completely the activity of the initial fresh catalyst. Its suitability was further demonstrated in consecutive HDC-regeneration runs where the catalyst showed a constant activity. This regeneration procedure is particularly promising given its fast mode of action, simplicity and low-cost. |
| Databáze: | OpenAIRE |
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