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A Robust Au/ZnCr2O4 Catalyst with Highly Dispersed Gold Nanoparticles for Gas-Phase Selective Oxidation of Cyclohexanol to Cyclohexanone

Achieving uniformly dispersed and stable nanoparticles of gold on oxide supports is a challenge in heterogeneous catalysis. Here, we show that zincochromite (ZnCr2O4) is a promising support for obtaining high and stable gold dispersion. Despite a low surface area of ZnCr2O4, finely dispersed gold (∼3–4 nm particles) could be obtained by a simple deposition–precipitation method, pointing to strong gold–support interactions. Using a combination of XRD, XPS, SEM, TEM, HAADF-STEM, and IR spectroscopy, we confirmed that the calcination temperature of the ZnCr2O4 support had a substantial influence on the crystallinity, morphology, and acidic properties of thereof derived Au/ZnCr2O4 catalysts. Gold supported on a high-temperature (≥700 °C) calcined ZnCr2O4 support displayed the best catalytic performance in gas-phase oxidation of cyclohexanol to cyclohexanone, which is an important intermediate in the chemical industry. When calcined at 800 °C, the material did not show any sign of deactivation in a 90 h stabil...