Facile preparation of egg-shell-type pellet catalysts using immiscibility between hydrophobic solvent and hydrophilic solution: Enhancement of catalytic activity due to position control of metallic nickel inside alumina pellet

Abstract Egg-shell-type catalysts, in which active components were selectively located outer region of pellet, have been prepared to effectively utilize catalytically active components in the reactions with high gas-hourly space velocity conditions. We developed a new and facile preparation method for egg-shell catalysts using immiscibility between hydrophobic solvent preoccupied inside pellet and aqueous hydrophilic precursor solution. A series of alcohols, propanol, butanol, pentanol and so on, were used as hydrophobic solvents to retard the penetration of aqueous metal precursor solutions. After drying solvents and proper calcination and reduction, catalytically active components, metallic nickel particles, were selectively located in the outer region of pellet. Owing to the selective deposition of metallic particles, the egg-shell catalysts showed higher conversion of methane in steam methane reforming than homo-type catalysts, which has homogeneous distribution of metal particles on the entire range of pellet, as the space velocity increased from 6000 to 30,000 h −1 .