(352g) Synergetic Effect of Ultrafine Nico Bimetallic Alloy Nanoparticles Derived from Bimetal-Organic Frameworks

Reducing the size of metal particles to the subnanometer-scale in
catalysis is attractive, because metal clusters composed of several atoms
exhibit novel properties that differ greatly from those predicted by simple
scaling laws. In this study, highly dispersed NiCo bimetallic alloy
nanoparticles have been successfully immobilized on the SiO₂
frameworks by using hetero-nuclear metal-organic frameworks (MOFs) as metal
alloy precursors. Catalyst characterizations revealed that the average size of NiCo
alloy particles was less than 1 nm, with a total metal loading of about 20 wt%.
Compared with individual Ni or Co MOF-derived catalysts and the catalysts
prepared by the conventional impregnation method, the ultrafine NiCo/SiO₂-MOF
catalyst showed a much better catalytic performance in the catalytic
hydrogenation of furfuryl alcohol (FA) to tetrahydrofurfuryl alcohol (THFA)
under mild conditions, giving 99.8% conversion of FA and 99.1% selectivity to
THFA. It was found that a significant synergistic effect existed between Co and
Ni within the subnanometer NiCo/SiO₂-MOF catalyst, which was twice
and 20 times more active than Ni/SiO₂-MOF and Co/SiO₂-MOF,
respectively. In contrast, such a synergistic effect is not observed within the
NiCo/SiO₂-IMP catalyst prepared by conventional impregnation. This
interesting finding of size-dependent bimetallic synergetic effect provides
guidance for enhancing the activity of bimetallic catalysts.

Figure 1. Reaction constants of different catalysts for FA
hydrogenation to THFA.