Enhanced activity for co preferential oxidation over cuo catalysts supported on nanosized ceo2 with high surface area and defects

Figure 1A shows the N₂ adsorption-desorption isotherm and pore size distribution of n-CeO₂ and p-CeO₂. Table 1 lists the BET surface areas, average pore diameters and lattice parameters of n-CeO₂ and p-CeO₂. Their N₂ adsorption-desorption isotherms both correspond to typical type IV isotherms. n-CeO₂ exhibits an H2-type hysteresis loop in the relative pressure (P/P₀) range from 0.4 to 1.0, suggesting the existence of mesopores due to the agglomeration of particles [10,17]. p-CeO₂ shows an H3-type hysteresis loop in the relative pressure (P/P₀) range from 0.8 to 1.0, which indicates the generation of irregular pores in p-CeO₂ [16]. From the inset of Figure 1A, we can see that n-CeO₂ shows a narrow distribution of pore size between 5 nm and 15 nm. For p-CeO₂, the pore size distribution is wider and in the range of 5–50 nm. As listed in Table 1, the pore volumes of n-CeO₂ and p-CeO₂ are 0.176 and 0.083 m³·g⁻¹, and the average pore diameters are 5.6 and 18.7 nm, respectively. n-CeO₂ possesses a large surface area, reaching to 130 m²·g⁻¹, while p-CeO₂ exhibits a relatively small surface area of 35 m²·g⁻¹. The larger pore volume and smaller pore size benefit faster diffusion of reactant gas in catalysts. The larger surface area is beneficial to the high dispersion of copper species which can form more potential active sites.