Macroporous Monolithic Pt/γ-Al2O3 and K–Pt/γ-Al2O3 Catalysts Used for Preferential Oxidation of CO.

Macro-porous monolithic γ-Al2O3 was prepared by using macro-porous polystyrene monolith foam as the template and alumina sol as the precursor. Platinum and potassium were loaded on the support by impregnation method. TG, XRD, N2 adsorption–desorption, SEM, TEM, and TPR techniques were used for catalysts characterization, and the catalytic performance of macro-porous monolithic Pt/γ-Al2O3 and K–Pt/γ-Al2O3 catalysts were tested in hydrogen-rich stream for CO preferential oxidation (CO-PROX). SEM images show that the macropores in the macro-porous monolithic γ-Al2O3 are interconnected with the pore size in the range of 10 to 50 μm, and the monoliths possess hierarchical macro-meso(micro)-porous structure. The macro-porous monolithic catalysts, although they are less active intrinsically than the particle ones, exhibit higher CO conversion and higher O2 to CO oxidation selectivity than particle catalysts at high reaction temperatures, which is proposed to be owing to its hierarchical macro-meso(micro) -porous structure. Adding potassium lead to marked improvement of the catalytic performance, owing to intrinsic activity and platinum dispersion increase resulted from K-doping. CO in hydrogen-rich gases can be removed to 10 ppm over monolithic K–Pt/γ-Al2O3 by CO-PROX. [ABSTRACT FROM AUTHOR]