Fabrication of Spherical Silica Particles from Sodium Silicate and Their Application as Support Materials for Ruthenium-based Catalysts for the Hydrogenation of Supercritical Carbon Dioxide into Formic Acid

Abstract

Spherical silica nanoparticles were fabricated from sodium metasilicate solution using urea as a precipitant. Homogeneity of the silica particles was improved by adjusting the ratio of sodium metasilicate to urea, and their size was adjusted between 20 and 1600 nm by adjusting the amount of sodium metasilicate and urea. Supported ruthenium catalysts were prepared by impregnation method using the silica spheres as a support of the catalysts. The amount of supported ruthenium depended on the ruthenium concentration during the impregnation process. The catalytic activity for hydrogenation of carbon dioxide into formic acid increased with increasing their ruthenium contents. The activity did not significantly depend on the particle size of the silica supports; however, the amount of ruthenium deposited on the particles depended on the particle size of the silica supports, with a larger amount of ruthenium being immobilized on the silica supports with a smaller particle size.