Highly dispersed palladium nanoparticles on ultra-porous silica mesocellular foam for the catalytic decarboxylation of stearic acid

Abstract

The synthesis, characterization, and application of well-dispersed palladium nanoparticles supported on a mesocellular silica support in the catalytic decarboxylation of stearic acid are reported. Ultra-large pore volume silica mesocellular foam is synthesized as the catalyst support, with amorphous cell-and-window pore diameters of 37 nm and 17 nm, respectively. Silane surface functionalization is employed to ensure thorough metal distribution by providing binding sites for loading of palladium precursor salts. After calcination and reduction, chemisorption and microscopy results indicate ∼2 nm palladium particles are distributed throughout the silica support at 5 wt.% metal loading. The catalysts are active in the batch decarboxylation of stearic acid in nitrogen atmosphere at 300 °C, reaching conversions of 85–90% after 6 h with complete selectivity to the decarboxylation product n-heptadecane. Lower conversions (<15%) are observed after 6 h for the batch decarboxylation of ethyl stearate in nitrogen atmosphere at 300 °C, with 87% selectivity to the decarboxylation product n-heptadecane, and 13% as the intermediate stearic acid.