Gold catalysts on TiO2 support for preferential oxidation of CO in H2 stream: Effect of base agent

Au/TiO2 catalysts were prepared by deposition–precipitation method using various bases such as NaOH, NH4OH and urea. The catalysts were characterized by ICP-MS, XRD, TEM and XPS. The catalytic activity of these catalysts has been investigated for preferential oxidation of carbon monoxide in hydrogen stream. A high gold dispersion and narrow size distribution was obtained for Au/TiO2 catalysts by using different precipitating reagents, such as NaOH, NH4OH and urea. Au/TiO2 catalyst prepared by using NaOH as base agent shows higher deposition of gold on the TiO2 support when compared with other base agents. The uptake of gold on TiO2 decreased as the pH value increased from 5 to 9. The catalytic activity of CO oxidation increases as the metal loading increases and CO selectivity decreased with increasing reaction temperature on all catalysts. Au/TiO2 catalyst prepared by using NaOH as the base agent at low pH ∼6 is found to be the better catalyst, henceforth the catalytic activity is found to be higher for preferential oxidation of CO in H2 stream at 80 °C.