Semi-permeable particle can be used to facilitate chemical reactions. The semi-permeable particles are permeable to molecules having a molar mass of 1000 Daltons or less, have a mode particle size of at least 1 μm, and comprise nanoparticles of catalytically active metallic materials disposed within at least some of multiple discrete cavities in the continuous polymeric phase. The nanoparticles of catalytically active metallic materials (a) comprise one or more elements selected from Groups 8, 9, 10, and 11 of the Periodic Table, and (b) have an effective diameter of at least 1 nm and up to and including 200 nm.