Metal catalysis with nanostructured metals supported inside strongly acidic cross-linked polymer frameworks: Influence of reduction conditions of Au ~(III)-containing resins on metal nanoclusters formation in macroreticular and gel-type materials

摘要

Synthesis of gold nanoclusters inside strongly acidic ion exchangers, in beaded forms, is carried out under different conditions. After metallation with [Au(en) _2]Cl _3 and reduction with H _2 in the absence of any added aqueous phase, Au 0/-SO 3H nanocomposites are produced that are compared with Au ~0/-SO _3 ~- Na ~+ ones obtained with NaBH _4 as reductant in aqueous medium. Reduction conditions allow control of both distribution and size of the metal nanoclusters. Metal distribution inside the polymer beads appears to be quite homogeneous under the hydrogen reduction conditions and metal nanoclusters size turns out to be size-controlled in the 3-5 nm range. In the case of the action of NaBH _4 in water, metal distribution inside the polymer beads appears to be quite peripheral and the metal nanoclusters turn out to be size-controlled but definitely larger, 5-7 nm, than those obtained by action of molecular hydrogen.