Disintegration or redispersion of supported sintered gold nanoparticles （Au NPs） in the presence of alkyl halide can give catalyst regeneration or redispersion of sintered Au catalysts. The selectivity of alkyl hali...Disintegration or redispersion of supported sintered gold nanoparticles （Au NPs） in the presence of alkyl halide can give catalyst regeneration or redispersion of sintered Au catalysts. The selectivity of alkyl halides, temperature and size distributions were investigated to elucidate the redispersion of Au NPs during halide-induced decomposition. This study proved that the alkyl halide induced the redispersion of sintered Au NPs which depended on the R-X （X = I, Br, CI） bond dissociation energy （BDE） and thus provided a simple descriptor for the regeneration of inactive supported Au cata- lysts. A correlation between the BDE of R-X and dispersion efficiency was established. The tendency for disintegration and redispersion followed the R-X BDE of the alkyl halide. Compared to alkyl chlorides and bromides, iodides were more efficient for redispersing sintered Au NPs. As a descriptor, the BDE of R-I played a crucial role in particle redispersion. These findings provided in- sights into the mechanism of organic halide-induced Au NP disintegration and the effect of the hal- ide type on the redispersion of sintered catalysts.展开更多
A series of carboxylated long chain polyethylene glycols(abbreviated as PEGCOOH) has been synthesized and used to support chloroplatinic acid.These supported catalysts were then tested for their efficiency in the hydr...A series of carboxylated long chain polyethylene glycols(abbreviated as PEGCOOH) has been synthesized and used to support chloroplatinic acid.These supported catalysts were then tested for their efficiency in the hydrosilylation of alkenes.The factors affecting their catalytic properties,e.g.relative molecular mass of polyethylene glycol,reaction temperature,platinum content,and type of alkenes,have been studied.It was found that the activity of the platinum catalyst decreased with increasing length of the polyethylene glycol chain,and increased with reaction temperature.Moreover,these catalysts could be reused several times without a noticeable decrease in activity or selectivity.The reaction pathway leading to excellent selectivity for the β-adduct of hydrosilylation of alkenes with triethoxysilane catalyzed by this catalysis system was discussed.展开更多
文摘Disintegration or redispersion of supported sintered gold nanoparticles （Au NPs） in the presence of alkyl halide can give catalyst regeneration or redispersion of sintered Au catalysts. The selectivity of alkyl halides, temperature and size distributions were investigated to elucidate the redispersion of Au NPs during halide-induced decomposition. This study proved that the alkyl halide induced the redispersion of sintered Au NPs which depended on the R-X （X = I, Br, CI） bond dissociation energy （BDE） and thus provided a simple descriptor for the regeneration of inactive supported Au cata- lysts. A correlation between the BDE of R-X and dispersion efficiency was established. The tendency for disintegration and redispersion followed the R-X BDE of the alkyl halide. Compared to alkyl chlorides and bromides, iodides were more efficient for redispersing sintered Au NPs. As a descriptor, the BDE of R-I played a crucial role in particle redispersion. These findings provided in- sights into the mechanism of organic halide-induced Au NP disintegration and the effect of the hal- ide type on the redispersion of sintered catalysts.
基金Supported by the Educational Commission of Zhejiang Province of China (Y201017419)Zhejiang Province Program(2008C14041)
文摘A series of carboxylated long chain polyethylene glycols(abbreviated as PEGCOOH) has been synthesized and used to support chloroplatinic acid.These supported catalysts were then tested for their efficiency in the hydrosilylation of alkenes.The factors affecting their catalytic properties,e.g.relative molecular mass of polyethylene glycol,reaction temperature,platinum content,and type of alkenes,have been studied.It was found that the activity of the platinum catalyst decreased with increasing length of the polyethylene glycol chain,and increased with reaction temperature.Moreover,these catalysts could be reused several times without a noticeable decrease in activity or selectivity.The reaction pathway leading to excellent selectivity for the β-adduct of hydrosilylation of alkenes with triethoxysilane catalyzed by this catalysis system was discussed.
