A structured catalyst: Noble metal supported on a plate-type zirconia substrate prepared by anodic oxidation for steam reforming of hydrocarbon Original Research Article

A structured catalyst: noble metal supported on a plate-type zirconia substrate was prepared by subjecting a zirconium plate to a process consisting of anodic oxidation in an oxalic acid bath and calcination in the air, followed by rhodium or ruthenium component deposition by the dipping treatment. The catalytic performances of the prepared catalysts were evaluated for steam reforming of n-butane and propane. The substrate surface was significantly corroded by the anodic oxidation and calcination, and a rugged zirconia layer about 100 μm thick was formed. The crystalline state of zirconia was mainly monoclinic and tetragonal. In steam reforming of n-butane, the structured ruthenium catalyst had some activity, while the activity of the rhodium catalyst exceeded that of the commercial catalyst. For the rhodium catalyst, its reforming activity was improved by changing the temperature of dipping bath and the number of dips for adjustment of the rhodium deposition state. The rhodium catalyst prepared by dipping twice at a bath temperature of 25 °C has the largest metal surface area and a higher metal dispersion, which were thought to be the causes for the high performance. In steam reforming of propane, the rhodium catalyst showed a significantly higher activity than the commercial catalyst. The rhodium catalyst was less prone to deterioration of activity due to n-butane and propane reforming.