With this award funded by the Chemical Catalysis Program, Professor Ryan Richards of the Colorado School of Mines will perform research directed towards imparting stability to nanostructured catalysts. The work is based upon a preparation method that enables control of the morphology and porous structure of highly dispersed "robust" gold nanoparticles in the sol-gel process. Characterization of this system provided evidence of the presence of nanoscale gold particles (4nm) and that the mesoporous network is uninterrupted and analogous to SBA-15. This system demonstrated higher activity for the oxidation of n-hexadecane than systems with similar size gold particles immobilized in the pore network of mesoporous silica. This suggests that some aspect of the intercalated material greatly influences the catalytic properties (at least for this reaction). Additionally, these materials demonstrated stability at temperatures up to 750 degrees Centigrade without evidence of particle growth and were recyclable. Thus, the basis for the proposed work is to pursue the hypothesis that intercalation in mesoporous silica can yield highly active and "robust" catalytic systems entailing development of a fundamental understanding of their preparation, characterization, and behavior in select catalytic reactions. Although numerous approaches for the immobilization of nanoscale catalysts have been described in the literature, this approach offers a unique combination of properties (i.e., tunable porosity, thermal stability, increased activity, broad applicability).
An ideal "green" catalyst would use air as the oxidant under mild conditions for oxidation reactions, be recyclable and avoid the wasteful addition of reducing agents and solvents. This work aims to accomplish all of these goals and represents the conceptual foundation for the ability to form intercalated nanostructures. Further, the preparation methodology may be transferable to other metal or alloy nanoparticles as well as discrete molecules. It represents a new approach to imparting chemical and mechanical robustness, a current impediment to the broad application of nanoscale materials in catalysis. The envisioned materials may be employed under harsh reaction conditions (temperature and pressure) in which they would typically sinter or aggregate. Catalytic processes are of vital economic importance. The ability to develop 'green' catalysts with improved activity and selectivity may positively impact the environment and improve the economic feasibility and resource efficiency of important industrial processes. The project includes student training and outreach programs to K-12.
