Synthesis of Supported Mesoporous Catalysts Using Supercritical CO₂

Abstract

Metal and metal oxide nanoparticles have attracted increased attention due to their unusual physical and chemical properties. The nature, dispersion, and size of the nanoparticles are key factors in determining the activity and selectivity of the supported catalysts. Supercritical fluid deposition (SCFD) is a promising method to deposit metallic nanoparticles and films on inorganic porous supports. CO 2 is the most commonly used supercritical fluid (sc-CO 2) for material synthesis because it is nontoxic, nonreactive, nonflammable, and inexpensive. This work presents the synthesis of cobalt, nickel, and ruthenium nanoparticles on MCM-41, Al-MCM-41, MCM-48, and activated carbon supports in sc-CO 2. Batch and continuous deposition are studied, with two high-pressure reactor configurations: column or alternative (sandwich). To avoid the length of the bed being too long, the reagents were separated into smaller amounts and placed alternately, keeping the total mass of the precursor and support constant. The prepared samples were characterized by scanning electron (SEM/EDX) and transmission electron microscopy (TEM).