Magnetically Recoverable Catalysts using Hierarchical Magnetite/Silica Nanoassemblies as Supports Yadong Yin, Department of Chemistry, University of California, Riverside, CA 92521 Recoverable catalysts: We aim to develop a general method for protecting supported metal nanocatalysts from coagulation while at the same time maintaining their high catalytic activity. We have developed a process for the fabrication of mesoporous silica protected core-satellite nanocomposite catalysts through a series of simple sol-gel and surface-protected etching processes. With the support from the ACS PRF grant, we have been actively exploring methods to assemble catalytic nanoparticles in appropriate host materials to form composite nanostructures that can improve the stability, recyclability, and catalytic selectivity of nanocatalysts. A “surface-protected etching” strategy has been used for creating mesoporous structures in the outer oxide shell, thus allowing controllable mass transfer during catalytic reactions. The incorporation of superparamagnetic cores to the composite structures allows convenient magnetic separation of catalysts for liquid-phase reactions. We have also carried out tests to study the stability of the mesoporous-shell-protected catalysts, and found that the metal nanoparticle catalysts gained significant stability against thermal sintering.