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Abstract
Alginate was used for the immobilization of an alkylphosphonium ionic liquid (IL). The IL-alginate resin served for Pd(II) binding from HCl solutions. After chemical reduction of Pd(II), the composite was tested for the hydrogenation of nitrophenols (NPs) and 4-nitroaniline (4-NA) using sodium formate or formic acid as the hydrogen donor (HD) in batch system. The influence of agitation speed, particle size, type, and concentration of HD and pH has been evaluated for 2-NP, 3-NP, 4-NP, and 4-NA (into 2-aminophenol, 2-AP, 3-AP, 4AP and p-phenylenediamine, respectively). Agitation speed does not interfere on hydrogenation kinetics: the film diffusion is not the rate limiting step. The pH influences the catalytic efficiency and the kinetics: pH close to 2-3 being better than pH 1. HD concentration does not influence kinetic profiles above 0.25 M. The modeling of kinetic curves depends on experimental conditions: zero-order rate equation at pH 1, and variable order reaction rate or reversible reaction rate for other pHs, depending on HD concentration and type. Supplemental materials are available for this article. Go to the publisher's online edition of Separation Science and Technology to view the free supplemental file.
ACKNOWLEDGEMENTS
The financial support from Agence Nationale de la Recherche to the BiopSIL project (ANR-08-CP2D-02) is greatfully acknowledged. Cytec (Canada) is acknowledged for kindly supplying the Cyphos IL-111 sample. The Region Languedoc-Roussillon is acknowledged for the financial support for J.C. research stay in EMA. The authors thank J.-M. Taulemesse (from Centre des Matériaux de Grande Diffusion at Ecole des Mines d'Alès) for SEM and SEM-EDAX analyses.
Notes
k0 (min−1), k1 (min−1), k2 (L mg−1): kinetic coefficients; Ceq (mg L−1): residual equilibrium concentration (case of reversible kinetic model).