Stabilizer effects on the synthesis of gold-containing microparticles. Application to the liquid phase oxidation of glycerol
Résumé
Gold-containing poly(urea-formaldehyde) microparticles were prepared by
the in situ polymerization method using a series of stabilization agents
with different chemical nature. The effects of cetyltrimethylammonium
bromide (CTAB), sodium dodecyl sulfate (SDS), polyvinyl pyrrolidone
(PVP), polyvinyl alcohol (PVA) and tetrakis(hydroxymethyl)phosphonium
chloride (THPC) on the morphology, the particle size of encapsulated
gold, the gold particle size distribution and the encapsulation
efficiency were investigated by using scanning electron microscopy,
X-ray diffraction and atomic absorption analyses. The chemical nature of
stabilizer had a marked influence on both the encapsulated gold
particle size and the encapsulation efficiency. Both gold particle size
and gold encapsulation efficiency increased when decreasing the
stabilizer polarity number. All the microparticles here prepared were
tested in the liquid phase selective oxidation of glycerol. The glycerol
conversion increased and the glyceric acid selectivity decreased when
decreasing gold particle sizes. Results showed that use of stabilizers
with hydrophobic surfaces enhanced the selectivity to C-3 products in
the resulting catalysts. On the other hand, the use of stabilizers with
hydrophilic surfaces increased the C-C bond cleavage products in the
resulting catalysts. (C) 2014 Elsevier Inc. All rights reserved.