Gold nanoparticles confined in ordered mesopores: Size effect and enhanced stability during gas-phase selective oxidation of cyclohexanol

•Mesoporous silica supported gold catalysts show size effect during alcohol oxidation.•High selectivity is found for gas-phase cyclohexanol to cyclohexanone transformation.•Gold catalysts exhibit good stability and long lifetime without coke formation.

Gold nanoparticles (AuNPs) encapsulated in the extra-large spherical cages of ordered mesoporous silica EP-FDU-12 with controlled and narrow size distributions have been investigated for the gas-phase oxidation of cyclohexanol. The size effect of AuNPs was demonstrated that the highest TOF for oxidation of cyclohexanol was 939 h−1 at 230 °C when the resulting particle size was in the range of 5-6 nm. The smaller or larger AuNPs ranging from 3.3 to 14.2 nm led to poor catalytic performances in the cyclohexanol oxidation. Importantly, AuNPs loaded in EP-FDU-12 catalyst exhibited remarkably long lifetime (>550 h) without obvious mass-specific activity decrease and poisonous coke formation, which will light the path for the large-scale industrialization of fine chemicals over noble metal catalysts.

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