A study on pore size control of a plate-type alumina catalyst

Preparation of a plate-type catalyst by anodization and sealing treatment has been proposed. Commercial aluminum plate was anodized in 4wt% oxalic acid solution at 20 degrees C. An alumina layer was formed on the plate surface. Meso-pores ranging from 20 to 30 nm in radius were formed in the anodized alumina film by changing the current density of anodization. After the anodization, the pores were enlarged to 40nm in radius by soaking the plate in oxalic acid solution. These pores could be sealed by hydration. The temperature and treatment time of hydration were controlled and the pores were sealed to 2-40 nm in radius and showed double peaks in their pore size distribution. The alumina on aluminum plates was used for support of catalysts. These supports differing in pore size distribution were impregnated with platinum. The impregnation was done (a) concurrently with hydration by chloroplatinic acid aqueous solution, or (b) using sodium silicate-acetone solution of chloroplatinic acid. The physical properties of three catalysts prepared by these methods were determined and compared.