Au nanoparticles assembled on palygorskite: Enhanced catalytic property and Au–Au2O3 coexistence

•Au nanoparticles were assembled on palygorskite to form nanocomposites.•Au nanoparticles existed in the form of Au and Au2O3.•Oxygen vacancy of Au2O3 was beneficial to the enhancement of catalytic property.•Reaction rate of o-DCB showed second order with activation energy of −3.4 kJ/mol.

Au nanoparticles were assembled on palygorskite (PAL) to form Au/PAL nanocomposites via a deposition–precipitation method. Samples were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and gas chromatography (GC). Results indicated that Au nanoparticles, with a particle size of 2–7 nm, were uniformly immobilized on the surface of PAL with the coexistence of Au and Au2O3. Ortho-dichlorobenzene (o-DCB) was first fixed on Au2O3 then completely oxidized to CO2, H2O, HCl by metallic Au. The reaction rate of o-DCB was approximately second order with calculated activation energy of −3.4 kJ/mol, while the reaction order of O2 was zero order under sufficient oxygen. The catalytic activity could reach 99% at a Au/(Au + Au2O3) molar ratio of 0.83, three times of that without PAL support. Mechanism for enhanced catalytic activity under Au–Au2O3 coexistence system was discussed.

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