Synthesis and stabilization of gold nanoparticles inside the mesoporous silica mixed: the proper efficiency of alcohol oxidation

Stabilizing gold nanoparticles (AuNPs) within the desired size range is critical to realize their promising catalytic performance in many important reactions. Herein, we investigate the anti‐sintering properties of cubic mesoporous silica (FDU‐12) as a function of pore entrance size. Simple adjustments to the type of organic template and reaction temperature enable the successful synthesis of FDU‐12 with controllable entrance sizes (< 3, 3–5 and 7 nm). Excellent anti‐sintering properties are observed for FDU‐12 with a sub‐5‐nm entrance size (3–5 nm) over a wide loading concentration (1.0–8.3 wt%) and the AuNPs can be stabilized within a 4.5–5.0‐nm range after calcination at 550 °C in air for 5 h. Smaller entrance size (< 3 nm) prevents the ingress of 3‐nm AuNPs to the mesopores and results in low loading capacity and sintering. Conversely, FDU‐12 possessing a larger entrance size (7 nm) shows promising anti‐sintering properties at high loading concentrations, although catalytic performance is significantly lost at lower concentrations (e.g. 2.1 wt%, 14.2 ± 5.5 nm). Different anti‐sintering mechanisms are proposed for each of the different FDU‐12 entrance sizes. Additionally, catalytic data indicates that the obtained 4.5‐nm AuNPs supported on FDU‐12 with a sub‐5‐nm entrance size exhibit excellent mass‐ specific activity (1544 mmol gAu−1 h−1) and selectivity (> 99%) at 230 °C for the gas‐phase selective oxidation of cyclohexanol.

Keywords:

Gold nanoparticle , Cubic mesoporous silica , Entrance size Anti‐sintering , property , Alcohol oxidation