Choji Fukuhara

Structured Catalysts Prepared by Electroless Plating Technique onto a Metal Substrate, for a Wall-Type Hydrogen Production System

This article reviews our works on the structured catalysts for a wall-type hydrogen production system including methanol steam reforming (MSR), CO shift reaction (CO SR) and methanol decomposition (MD). The structured catalysts were copper-based, palladium-based and nickel-based catalysts. Such a series of structured catalysts were prepared by the electroless plating technique that is a novel method for preparing a structured type catalyst onto a metal-substrate. The copper-based catalyst exhibited high performance for MSR and CO SR, the palladium-based catalyst high for MSR, and the nickel-based catalyst high for MD. The catalytic properties of these catalysts were affected by the difference of the plating condition and the pretreatment condition prior to the reaction. In the copper-based catalyst, the reforming and shift activities were enhanced by the oxidation treatment. One of the factors of such activity enhancement by the oxidation was thought to be in close proximity existence of copper and zinc atoms. A lot of monodentate-type formate species having high reactivity was formed on the oxidized catalyst, which would be correlated to the activity enhancement. In the palladium-based catalyst, the reforming activity was improved by the continuous reduction treatment followed by the oxidation. Such continuous pretreatment formed the PdZn alloy species thought to be a reforming site in the surface layer. The decomposition performance of the nickel-based catalyst depended on the ratio of the crystallite size of nickel particles to that of aluminum particles. The electronic influence of zinc and phosphorous components incorporated in the plated layer contributed to the improvement of the selectivity of product.

Effect of Promoter Addition on Water Gas Shift Property over Structured-Type Iron Oxide Catalyst

This study deals with the development of a high performance catalyst for the water gas shift reaction (WGS) by doping a promoter (Cr, Mn, Co, Ni, Cu) and optimizing the potassium loading on a structured-type iron oxide catalyst. Doping a promoter was effective for enhancing the WGS activity over the iron oxide-type catalyst, except for the Mn- and Cu-doping. Especially, the Ni-doping catalyst displayed a better performance than the other catalysts. In addition, loading a potassium component was found to have a positive effect on suppression of methanation as well as a drastic enhancement of the WGS activity.Graphical Abstract

Performance of Non-stoichiometric Perovskite Catalyst (AxCrO3−δ, A: La, Pr, Nd) for Dehydrogenation of Propane Under Steam Condition

The aim of this study was to clarify the effect of the non-stoichiometry in the AxCrO3−δ (A: La, Pr, Nd, 0.90 ≤ x ≤ 1.05) perovskite-type oxide on the dehydrogenation performance of propane using steam (DHP-S). The slight change in the molar ratio of the A-site (=La, Pr, Nd) to the B-site cation (=Cr) from the stoichiometric composition (A/B = 1) significantly affected the dehydrogenation performance. For the La-based catalyst, the LaxCrO3−δ catalyst with 0.90 ≤ x ≤ 0.97 displayed a relatively high activity, while the catalyst with 0.97 < x ≤ 1.05 did not show any activity for the DHP-S. The perovskite catalyst having the A-site defect presented a high performance for the DHP-S regardless of the types of A-site cation. The Nd0.95CrO3−δ catalyst displayed the highest performance among the A-site defective perovskite catalysts. The Nd0.95CrO3−δ catalyst also showed a superior stability compared to the CrOx/γ-Al2O3 catalyst. Based on an XPS measurement, the reduction–oxidation (redox) property was improved by changing the Nd/Cr molar ratio from the stoichiometric composition (Nd/Cr = 1) to a non-stoichiometric composition. Such a good redox property would produce a high performance for the DHP-S.Graphical Abstract