Gold nanoparticles-assisted sodium borohydride supported on titania as a catalyst for the oxidative steam reforming of methanol and CO oxidation

Abstract

Gold (Au) nanoparticles (NPs) and Au-copper (ii) oxide (CuO) supported on titania (TiO2) catalysts prepared by deposition-precipitation were investigated for the oxidative steam reforming of methanol (OSRM) and CO oxidation reactions. The effect of sodium borohydride (NaBH4) as a reducing agent during the Au catalyst preparation was studied. Characterization by high-resolution transmission electron microscopy established that an optimal NaBH4 quantity provided small Au NPs of less than 5 nm diameter with a uniform distribution that exhibited a higher catalytic activity than the others in the OSRM. The Au-CuO catalysts formed with different metal atomic ratios were also synthesized and compared for their catalytic activities in the OSRM and CO oxidation reactions with those from Au/TiO2 and Cu/TiO2. All Au-CuO catalysts achieved the highest methanol conversion at 400 °C, whereas the monometallic Au provided an almost five-fold higher catalytic CO oxidation activity due to the possession of smaller particles than in the other catalysts.