Excellent performance of Cu-Mn/Ti-sepiolite catalysts for low-temperature CO oxidation

Abstract

The Ti-modified sepiolite (Ti-Sep)-supported Mn-Cu mixed oxide (yMn5Cu/Ti-Sep) catalysts were synthesized using the co-precipitation method. The materials were characterized by the X-ray diffraction scanning electron microscope, N2 adsorption-desorption, H2-TPR, O2-TPD, and XPS techniques, and their catalytic activities for CO oxidation were evaluated. It was found that the catalytic activities of yMn5Cu/Ti-Sep were higher than those of 5Cu/Ti-Sep and 30Mn/Ti-Sep, and the Mn/Cu molar ratio had a distinct influence on catalytic activity of the sample. Among the yMn5Cu/Ti- Sep samples, the 30Mn5Cu/Ti-Sep catalyst showed the best activity (which also outperformed the 30Mn5Cu/Sep catalyst), giving the highest reaction rate of 0.875 × 10–3 mmol·g–1·s–1 and the lowest T50% and T100% of 56°C and 86°C, respectively. Moreover, the 30Mn5Cu/Ti-Sep possessed the best low-temperature reducibility, the lowest O2 desorption temperature, and the highest surface Mn3+/Mn4+ atomic ratio. It is concluded that factors, such as the strong interaction between the copper or manganese oxides and the Ti-Sep support, good low-temperature reducibility, and good mobility of chemisorbed oxygen species, were responsible for the excellent catalytic activity of 30Mn5Cu/Ti-Sep. Open image in new window