Influence of Ce/Zr Ratio on the Synergistic Effect over CuCe sub(1-x)Zr sub(x)O sub(y)/ZSM-5 Catalysts for the Self-Sustained Combustion of Carbon Monoxide

• Published in: Combustion science and technology 2017-01, Vol.189 (8), p.1394-1415
• Main Authors: Zhao, Ruozhu, Hao, Qinglan, Bin, Feng, Kang, Running, Dou, Baojuan
• Format: Article
• Language: English
• Subjects: Carbon monoxide; Catalysis; Catalysts; Cerium oxide; Combustion; Copper; Surface chemistry; Zirconium
• ISSN: 0010-2202; 1563-521X
• DOI: 10.1080/00102202.2017.1297807

The self-sustained combustion of CO was studied over a series of CuCe sub(1-x)Zr sub(x)O sub(y)/ZSM-5 catalysts with different Ce/Zr molar ratios to evaluate the correlation of their structural characteristics with catalytic performance. The obtained results demonstrated that the activity of the cerium-containing catalysts was much higher than that of the CuZr sub(1)/Z, with the activity of CO combustion following the order: CuZr sub(1)/Z < CuCe sub(0.25)Zr sub(0.75)/Z < CuCe sub(0.5)Zr sub(0.5)/Z < CuCe sub(1)/Z < CuCe sub(0.75)Zr sub(0.25)Z. After cerium addition, the cerium-zirconium mixed oxides formed promoted the copper species well dispersed on the catalyst surface. The high activities of cerium-containing catalysts were closely related to the synergetic effects among the copper, cerium, and zirconium species, as the surface copper species provided sites for CO adsorption and the cerium-zirconium mixed oxides promote the activation of oxygen. The activities were probably also attributed to some copper species present as substitutional defects in the ceria lattice, which were more reducible than the copper clusters, minicrystals, and bulk CuO particles. The CuCe sub(0.75)Zr sub(0.25)/Z possessed excellent redox capacity, adsorption/activation properties for O and CO species, and therefore induced a self-sustained combustion of CO at the lowest temperature than that of other CuCe sub(1-x)Zr sub(x)O sub(y)/ZS M-5 catalysts.