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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]

Macroporous alumina monoliths have been prepared for the first time by filling polystyrene foam templates with alumina hydrosols which were prepared from pseudo-boehmite. Polystyrene foam templates were obtained by polymerization in highly concentrated water-in-oil (W/O) emulsions. The organic templates were subsequently removed by calcination. The effects of filling times of the alumina hydrosols, calcination temperature, and CTAB surfactant addition in the hydrosols on the properties of the monolith have been investigated. TG, FT-IR, SEM, TEM, N2 adsorption–desorption, and XRD techniques were used for characterization. The so prepared monoliths are the replicas of the polystyrene foams and are characterized with hierarchically porous structure. The macropores are interconnected and the macropore walls contain many meso and/or micropores. The hierarchically macro-meso-microporous structure can be controlled and tailored by adjusting the preparation conditions stated above and by addition of surfactant, and the organic components can be eliminated by high temperature calcination. When the calcination temperatures are 600 °C and 900 °C, the γ-Al2O3 phases are obtained, with SBET of 228 and 85 m2 g−1, respectively. When calcined at 1100 °C, the alumina monolith presents a single θ-Al2O3 phase with SBET of 80 m2 g−1. The 1300 °C calcined sample takes on the single α-Al2O3 phase with SBET of 5 m2 g−1 and compressive strength of 3.1 MPa. [ABSTRACT FROM AUTHOR]