How do you build a spherical catalytic nanoreactor in which a highly dispersed active phase in metal oxide is placed inside a porous envelope that constitutes a diaphragm separating the reaction space?
The Chemical Engineering Journal has published an article titled "Polymer template assisted construction of spherical Co3O4@meso-SiO2 yolk-shell nanoreactors for catalytic combustion of volatile organic compounds" by researchers from the Organic Technology Group of the Department of Chemistry at the Jagiellonian University. The publication describes a strategy for synthesizing core-shell systems based on using spherical polymer templates with defined adsorption properties, which opens a new chapter in research related to chemical nanoengineering. The path seems simple. It is enough to synthesize a spherical polymer characterized by a high adsorption capacity concerning a catalytically active phase precursor with a homogeneous grain size, which will determine the size of the formed nanoreactor. In the next step, surround the polymer particles with silica condensing in a solvent environment with the addition of a surfactant as a blowing agent. The SiO2 shell should be released from the surfactant remaining in its structure in the next step, generating its appropriate porosity so that the resulting polymer@SiO2 composite material can be saturated with the active phase precursor solution (e.g., transition metal ions). It should be remembered that the adsorption capacity of the polymer template is a key parameter to ensure proper aggregation of the precursor within the organic core. The material prepared this way must only undergo a heat treatment to eliminate the template and transform the precursor into a thermally stable form ready to work as a catalyst in processes running at elevated temperatures.
The developed synthesis strategy was verified on the example of a system containing Co3O4 nanoparticles encapsulated in mesoporous SiO2 shells with a diameter of about 250 nm and a wall thickness of about 50-60 nm. The fabricated materials were defined using a wide range of experimental methods, including thermal analysis, diffraction, adsorption, and microscopic and spectroscopic techniques, which allowed for confirmation of the receipt of the assumed structure. The Co3O4 phase particles protected from aggregation inside the core-shell structure remained easily reachable by molecules from the surrounding gas phase due to the appropriate porosity of the SiO2 envelope. The nanoreactor prepared in this way, providing optimal mass and heat transport throughout its volume, proved to be more than effective in the catalytic oxidation of volatile organic compounds, which is one of the most effective methods of eliminating unwanted organic air pollutants.
The research was supported with a project funded by the National Science Center under the Sonata program (project no. 2020/39/D/ST5/02703).
Congratulations to the authors!
According to the list of scientific journals and peer-reviewed materials of international conferences of the Ministry of Education and Science, the number of points assigned to the Chemical Engineering Journal is 200 (Impact Factor = 15.1)
Chem. Eng. J. 480 (2024) 148173