Toluene combustion over NiO nanoparticles on mesoporous SiO2 prepared by atomic layer deposition

• The catalytic activity of NiO/SiO2 catalysts for toluene combustion was measured.
• NiO catalysts can be efficient for toluene combustion below as well as above 200 °C.
• High activity of NiO/SiO2 catalysts is related to large surface area of mesoporous SiO2 substrates.

NiO nanoparticles were deposited on mesoporous SiO2 by atomic layer deposition (ALD) consisting of sequential exposures to Ni(Cp)2 and H2O. NiO/SiO2 catalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), inductively coupled plasma-optical emission spectroscopy (ICP-OES) and X-ray photoelectron spectroscopy (XPS). The catalytic activity of NiO/SiO2 catalysts for toluene combustion was measured in terms of toluene removal efficiency and conversion to CO2 and compared with that of commercial NiO nanoparticle catalysts. In order to investigate dependence of reaction temperature on toluene combustion, the toluene combustion experiments over NiO catalysts were carried out as various temperatures. We show that NiO catalysts can be efficient catalysts for toluene combustion below as well as above 200 °C. The catalytic activity per Ni atom of NiO/SiO2 catalyst was higher than that of unsupported NiO nanoparticles. This high activity of NiO/SiO2 catalysts is attributed to large surface area of mesoporous SiO2 substrates, which is able to adsorb a large amount of toluene molecules and expedite oxidation of toluene by spill-over.