Abstract
Supercritical fluids (SCFs) are used for the preparation of size-controlled nanoparticles in micro- and meso-porous silicas with different pore sizes, CnFSM-16 (n = 8, 10, 12 and 16; pore diameter = 1.6–3.5 nm), where the value n denotes the carbon number in the alkyl chain of the surfactant template. Precursors, M(acac)n (M = Pd, Rh, Ru and Fe; acac = acetylacetonate), dissolved in supercritical CO2 with acetone were loaded on the FSM-16, followed by reduction in a flow of H2 at 673 K or oxidation in a flow of O2 at 673 K. Nanoparticles of Pd, Rh, Ru and Fe2O3 can be impregnated on nanoporous silica with a uniform pore size, i.e. FSM-16. The particles are highly dispersed and have a small size distribution. Metal/metal oxide nanoparticles were impregnated inside the pores. For the impregnation of Pd nanoparticles, size-controlled Pd nanoparticles can be prepared in the FSM-16 nanoporous silica with a uniform pore size. The particle size linearly increased with the increase in the pore size of the FSM-16.
