Remarkably fast and selective recovery of a rhodium-containing catalyst with silica-based (poly)amine ion exchangers
2002; Royal Society of Chemistry; Volume: 26; Issue: 7 Linguagem: Inglês
10.1039/b200141a
ISSN1369-9261
AutoresJurjen Kramer, J. Erkelens, Ana Ríos García, W.L. Driessen, J. Reedijk,
Tópico(s)Extraction and Separation Processes
ResumoThree silica-based ion exchangers, containing monoamine (1), ethylenediamine (2) and diethylenetriamine (3) functionalities, have been examined for their capacity to recover the catalyst RhCl3, with emphasis on industrially important factors, such as kinetics and re-usability of the ion exchange materials. Ligand occupations have been found to lie between 40% and 55% (some 40–50 mg Rh per g ion exchanger), suggesting the predominant formation of complexes of the type ML2. The recovery proved to be most efficient with diluted mineral acids, and the initially adsorbed Rh3+ has been removed almost quantitatively (>95%) from 1. All ion exchangers display excellent recovery kinetics, with t1/2 values of adsorption never exceeding 60 s. Successive Rh recovery experiments indicate stable recovery percentages after the first recovery cycle, but show a gradual build-up of residual Rh with ion exchangers 2 and 3. Rh3+ has been extracted with high selectivity up to pH values as high as pH 4 in the presence of other transition metal ions, like Cu2+ and Ni2+.
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